National Library of Energy BETA

Sample records for ni pd pt

  1. Quantum valley Hall states and topological transitions in Pt(Ni, Pd)-decorated silicene: A first-principles study

    SciTech Connect (OSTI)

    Zhao, Bao; Zhang, Jiayong; Wang, Yicheng; Yang, Zhongqin

    2014-12-28

    The electronic states and topological behaviors of Pt(Ni, Pd)-decorated silicene are investigated by using an ab-initio method. All the three kinds of the adatoms prefer hollow sites of the silicene, guaranteeing the Dirac cones unbroken. The Pt(Ni, Pd)-decorated silicene systems all present quantum valley Hall (QVH) states with the gap opened exactly at the Fermi level. The gaps of the QVH states can be increased substantially by applying a positive electric field. Very fascinating phase transitions from QVH to quantum spin Hall (QSH) and then to QVH again are achieved in the Pt/Ni-decorated silicene when a negative electric field is applied. The QSH state in the Pd case with a negative electric field is, however, quenched because of relatively larger Rashba spin-orbit coupling (SOC) than the intrinsic SOC in the system. Our findings may be useful for the applications of silicene-based devices in valleytronics and spintronics.

  2. Effective core potential investigation of Ni, Pd, and Pt and their monohydrides

    SciTech Connect (OSTI)

    Rohlfing, C.M.; Hay, P.J.; Martin, R.L.

    1986-08-01

    The nickel, palladium, and platinum atoms and their monohydrides are investigated using effective core potentials (ECP's) recently introduced by Hay and Wadt (J. Chem. Phys. 82, 270, 299 (1985)). The palladium and platinum ECP's include relativistic effects. Two types of ECP's, which differ in their definition of the core region, are used in conjunction with large valence basis sets including f-italic functions. Electron correlation is incorporated by Mo-dash-barller--Plesset perturbation theory through fourth order. The results demonstrate the success of the ECP approximation: they are similar in quality to those of all-electron studies and at the same time are achieved at a reduced computational cost. Total correlation energies obtained with both types of ECP's are compared, and are found to be very sensitive to details of the basis set. Correlation effects are treated more consistently by the ECP's which include the outermost core orbitals in the valence region. The relative ordering of molecular states is calculated to be /sup 2/..delta..NiH, /sup 2/..sigma../sup +/ < /sup 2/..delta.. < /sup 2/Pi for PdH, and /sup 2/..delta..roughly-equal/sup 2/..sigma../sup +/PtH. Trends in bond lengths and bond strengths in the nickel, palladium, and platinum series are discussed.

  3. EuTZn (T=Pd, Pt, Au) with TiNiSi-type structure-Magnetic properties and {sup 151}Eu Moessbauer spectroscopy

    SciTech Connect (OSTI)

    Mishra, Trinath; Hermes, Wilfried; Harmening, Thomas; Eul, Matthias; Poettgen, Rainer

    2009-09-15

    The europium compounds EuTZn (T=Pd, Pt, Au) were synthesized from the elements in sealed tantalum tubes in an induction furnace. These intermetallics crystallize with the orthorhombic TiNiSi-type structure, space group Pnma. The structures were investigated by X-ray diffraction on powders and single crystals: a=732.3(2), b=448.5(2), c=787.7(2) pm, R{sub 1}/wR{sub 2}=0.0400/0.0594, 565 F{sup 2} values for EuPdZn, a=727.8(3), b=443.7(1), c=781.7(3) pm, R{sub 1}/wR{sub 2}=0.0605/0.0866, 573 F{sup 2} values for EuPtZn, and a=747.4(2), b=465.8(2), c=789.1(4) pm, R{sub 1}/wR{sub 2}=0.0351/0.0590, 658 F{sup 2} values for EuAuZn, with 20 variables per refinement. Together the T and zinc atoms build up three-dimensional [TZn] networks with short T-Zn distances. The EuTZn compounds show Curie-Weiss behavior in the temperature range from 75 to 300 K with mu{sub eff}=7.97(1), 7.70(1), and 7.94(1) mu{sub B}/Eu atom and theta{sub P}=18.6(1), 34.9(1), and 55.5(1) K for T=Pd, Pt, and Au, respectively, indicating divalent europium. Antiferromagntic ordering was detected at 15.1(3) K for EuPdZn and canted ferromagnetic ordering at 21.2(3) and 51.1(3) K for EuPtZn and EuAuZn. {sup 151}Eu Moessbauer spectroscopic measurements confirm the divalent nature of the europium atoms by isomer shift values ranging from -8.22(8) (EuPtZn) to -9.23(2) mm/s (EuAuZn). At 4.2 K full magnetic hyperfine field splitting is observed in all three compounds due to magnetic ordering of the europium magnetic moments. - Graphical abstract: Europium coordination in EuPdZn, EuPtZn, and EuAuZn.

  4. K[sub 10]In[sub 10]Z (Z = Ni, Pd, or Pt): Zintl phases containing isolated decaindium clusters centered by transition elements

    SciTech Connect (OSTI)

    Sevov, S.C.; Corbett, J.D. )

    1993-10-06

    The isostructural title compounds are obtained by high yield by slowly cooling the appropriate fused mixture in welded Ta. They occur in the orthorhombic space group Pnma, Z = 12, with a = 15.948(6), 16.043(6), 16.056(3) Angstroms, b = 32.565(6), 32.73(1) Angstroms, and c = 18.822(3), 18.895(5), 18.896(3) Angstroms for the Ni, Pd, and Pt derivatives, respectively. The structure of the Ni phase was refined by single crystal means (R, R[sub w] = 2.9, 3.3%) and shown to be constructed from the close-packed layers of Ni-centered In[sub 10] clusters that are separated by potassium ions both within and between the cluster layers. The compounds have large resistivities at room temperature by two-probe methods and are diamagnetic, with no moments on the transition metals. The geometry of the clusters can be derived from an ideal tetracapped trigonal prism (C[sub 3v]) of In centered by Z through axial compression along the 3-fold axis and opening of the capped triangular face so as to yield substantially equal Ni-In distances. The clusters are also related to Sb[sub 7][sup 3[minus

  5. Phase stabilities of pyrite-related MTCh compounds (M=Ni, Pd, Pt; T=Si, Ge, Sn, Pb; Ch=S, Se, Te): A systematic DFT study

    SciTech Connect (OSTI)

    Bachhuber, Frederik; Krach, Alexander; Furtner, Andrea; Söhnel, Tilo; Peter, Philipp; Rothballer, Jan; Weihrich, Richard

    2015-03-15

    Pyrite-type and related systems appear for a wide range of binary and ternary combinations of transition metals and main group elements that form Zintl type dumbbell anion units. Those representatives with 20 valence electrons exhibit an extraordinary structural flexibility and interesting properties as low-gap semiconductors or thermoelectric and electrode materials. This work is devoted to the systematic exploration of novel compounds within the class of MTCh compounds (M=Ni, Pd, Pt; T=Si, Ge, Sn, Pb; Ch=S, Se, Te) by means of density functional calculations. Their preferred structures are predicted from an extended scheme of colored pyrites and marcasites. To determine their stabilities, competing binary MT{sub 2} and MCh{sub 2} boundary phases are taken into account as well as ternary M{sub 3}T{sub 2}Ch{sub 2} and M{sub 2}T{sub 3}Ch{sub 3} systems. Recently established stability diagrams are presented to account for MTCh ordering phenomena with a focus on a not-yet-reported ordering variant of the NiAs{sub 2} type. Due to the good agreement with experimental data available for several PtTCh systems, the predictions for the residual systems are considered sufficiently accurate. - Graphical abstract: Compositional and structural stability of MTCh compounds is investigated from first principle calculations. A conceptional approach is presented to study and predict novel stable and metastable compounds and structures of low gap semiconductors with TCh dumbbell units that are isoelectronic and structurally related to pyrite (FeS{sub 2}). - Highlights: • Study of compositional stability of MTCh vs. M{sub 3}T{sub 2}Ch{sub 2} and M{sub 2}T{sub 3}Ch{sub 3} compounds. • Study of structural stability of known and novel MTCh compounds. • Prediction of novel stable and metastable structures and compounds isoelectronic to pyrite, FeS{sub 2}.

  6. A pathway for the growth of core-shell Pt-Pd nanoparticles

    SciTech Connect (OSTI)

    Narula, Chaitanya Kumar; Yang, Xiaofan; Li, Chen; Pennycook, Stephen J; Lupini, Andrew R

    2015-10-12

    In this study, the aging of both Pt-Pd nanoparticles and core-shell Pt-Pd nanoparticles has been reported to result in alloying of Pt with Pd. In comparison to monometallic Pt catalysts, the growth of Pd-Pt bimetallics is slower; however, the mechanism of growth of particles and the mechanism by which Pd improves the hydrothermal durability of bimetallic Pd-Pt particles remains uncertain. In our work on hydrothermal aging of core-shell Pt-Pd nanoparticles, synthesized by solution methods, with varying Pd:Pt ratio of 1:4, 1:1, and 4:1, we compare the growth of core-shell Pt-Pd nanoparticles and find that particles grow by migrating and joining together. The unique feature of the observed growth is that Pd shells from both particles open up and join, allowing the cores to merge. At high temperatures, alloying occurs in good agreement with reports by other workers.

  7. PT AND PT/NI "NEEDLE" ELETROCATALYSTS ON CARBON NANOTUBES WITH HIGH ACTIVITY FOR THE ORR

    SciTech Connect (OSTI)

    Colon-Mercado, H.

    2011-11-10

    Platinum and platinum/nickel alloy electrocatalysts supported on graphitized (gCNT) or nitrogen doped carbon nanotubes (nCNT) are prepared and characterized. Pt deposition onto carbon nanotubes results in Pt 'needle' formations that are 3.5 nm in diameter and {approx}100 nm in length. Subsequent Ni deposition and heat treatment results in PtNi 'needles' with an increased diameter. All Pt and Pt/Ni materials were tested as electrocatalysts for the oxygen reduction reaction (ORR). The Pt and Pt/Ni catalysts showed excellent performance for the ORR, with the heat treated PtNi/gCNT (1.06 mA/cm{sup 2}) and PtNi/nCNT (0.664 mA/cm{sup 2}) showing the highest activity.

  8. Deactivation Mechanisms of Pt/Pd-based Diesel Oxidation Catalysts

    SciTech Connect (OSTI)

    Wiebenga, Michelle H.; Kim, Chang H.; Schmieg, Steven J.; Oh, Se H.; Brown, David B.; Kim, Do Heui; Lee, Jong H.; Peden, Charles HF

    2012-04-30

    Currently precious metal-based diesel oxidation catalysts (DOC) containing platinum (Pt) and palladium (Pd) are most commonly used for the oxidation of hydrocarbon and NO in diesel exhaust hydrocarbon oxidation. The present work has been carried out to investigate the deactivation mechanisms of the DOC from its real-world vehicle operation by coupling its catalytic activity measurements with surface characterization including x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy. A production Pt-Pd DOC was obtained after being aged on a vehicle driven for 135,000 miles in order to study its deactivation behavior. The performance of the vehicle-aged part was correlated with that of the simulated hydrothermal lab aged sample assuming that Pt-Pd sintering plays a major role in irreversible catalyst deactivation. In addition to the hydrothermal sintering, the deterioration of hydrocarbon and NO oxidation performance was caused by surface poisoning. The role of the various aging factors in determining long-term performance in mobile applications will be discussed.

  9. Ni/Pd core/shell nanoparticles supported on graphene as a highly...

    Office of Scientific and Technical Information (OSTI)

    NiPd coreshell nanoparticles supported on graphene as a highly active and reusable ... Citation Details In-Document Search Title: NiPd coreshell nanoparticles supported on ...

  10. A pathway for the growth of core-shell Pt-Pd nanoparticles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Narula, Chaitanya Kumar; Yang, Xiaofan; Li, Chen; Pennycook, Stephen J; Lupini, Andrew R

    2015-10-12

    In this study, the aging of both Pt-Pd nanoparticles and core-shell Pt-Pd nanoparticles has been reported to result in alloying of Pt with Pd. In comparison to monometallic Pt catalysts, the growth of Pd-Pt bimetallics is slower; however, the mechanism of growth of particles and the mechanism by which Pd improves the hydrothermal durability of bimetallic Pd-Pt particles remains uncertain. In our work on hydrothermal aging of core-shell Pt-Pd nanoparticles, synthesized by solution methods, with varying Pd:Pt ratio of 1:4, 1:1, and 4:1, we compare the growth of core-shell Pt-Pd nanoparticles and find that particles grow by migrating and joiningmore » together. The unique feature of the observed growth is that Pd shells from both particles open up and join, allowing the cores to merge. At high temperatures, alloying occurs in good agreement with reports by other workers.« less

  11. Synthesis of Pd?Ru@Pt nanoparticles for oxygen reduction reaction in acidic electrolytes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sun, Yu; Hsieh, Yu-Chi; Chang, Li-Chung; Wu, Pu-Wei; Lee, Jyh-Fu

    2014-11-22

    Nanoparticles of PdRu, Pd?Ru, and Pd?Ru are synthesized and impregnated on carbon black via a wet chemical reflux process. X-ray diffraction patterns of the as-synthesized samples, PdxRu/C (x=1/3/9), suggest succesful formation of alloy without presence of individual Pd and Ru nanoparticles. Images from transmission electron microscope confirm irregularly-shaped nanoparticles with average size below 3 nm. Analysis from extended X-ray absorption fine structure on both Pd and Ru K-edge absorption profiles indicate the Ru atoms are enriched on the surface of PdxRu/C. Among these samples, the Pd?Ru/C exhibits the strongest electrocatalytic activity for oxygen reduction reaction (ORR) in an oxygen-saturated 0.1moreM aqueous HClO? solution. Subsequently, the Pd?Ru/C undegoes Cu under potential deposition, followed by a galvanic displacement reaction to deposit a Pt monolayer on the Pd?Ru surface (Pd?Ru@Pt). The Pd?Ru@Pt reveals better ORR performance than that of Pt, reaching a mass activity of 0.38 mA ?g? Pt, as compared to that of commercially available Pt nanoparticles (0.107 mA ?g? Pt). The mechanisms responsible for the ORR enhancement are attributed to the combined effects of lattice strain and ligand interaction. In addition, this core-shell Pd?Ru@Pt electrocatalyst represents a substantial reduction in the amount of Pt consumption and raw material cost.less

  12. CO adsorption and kinetics on well-characterized Pd films on Pt(111) in alkaline solutions

    SciTech Connect (OSTI)

    Arenz, M.; Stamenkovic, V.; Wandelt, K.; Ross, P.N.; Markovic, N.M.

    2002-01-01

    The electrochemistry of CO on a bare Pt(111) electrode as well as a Pt(111) electrode modified with pseudomorphic thin palladium films has been studied in alkaline solution by means of Fourier transform infrared (FTIR) spectroscopy. First Pd films were prepared and well characterized in UHV and subsequently transferred into the electrochemical cell for the registration of the voltammetric profiles. The charge corresponding to the formation of underpotentially deposited hydrogen (H{sub upd}) on these Pt(111)-xPd surfaces was established in sulfuric acid solution as a function of x (0 {le} x {le} 1 Pd monolayer (ML)). All subsequent measurements were then performed on electrochemically deposited palladium films using the above H{sub upd}-charge vs. Pd coverage relationship to evaluate the amount of electrochemically deposited palladium. FTIR spectra for CO adsorbed on one monolayer and a submonolayer coverage are compared to those of the unmodified Pt(111) surface, all surfaces having identical 2D lattice structures. Infrared absorption bands of CO bound on either Pt(111) or Pt(111)-1ML Pd are clearly distinguished. Spectra of CO adsorbed on Pd submonolayers show characteristic features of both CO bound to Pt and to Pd, indicating that on Pt(111)-xPd surfaces there is no coupling between Pt-CO{sub ad} and Pd-CO{sub ad} molecules. The kinetics of CO oxidation on these surfaces is determined either by rotating disk electrode (RDE) measurements or by FTIR spectroscopy, monitoring the CO{sub 3}{sup 2-} production. The oxidation of CO{sub ad} on Pt(111) and on Pd modified platinum surfaces starts at the same potential, ca. at 0.2 V. The oxidation rate is, however, considerably lower on the Pt(111)-xPd surfaces than on the Pt(111) surface. The kinetics of CO oxidation appears to be determined by the nature of adsorbed hydroxyl anions (OH{sub ad}), which are more strongly (less active) adsorbed on the highly oxophilic Pd atoms.

  13. Pt/Pd electrocatalyst electrons for fuel cells

    DOE Patents [OSTI]

    Stonehart, P.

    1981-11-03

    This invention relates to improved electrochemical cells and to novel electrodes for use therein. In particular, the present invention comprises a fuel cell used primarily for the consumption of impure hydrogen fuels containing carbon monoxide or carbonaceous fuels where the electrode in contact with the fuel is not substantially poisoned by carbon monoxide. The anode of the fuel cell comprises a Pd/Pt alloy supported on a graphitized or partially graphitized carbon material. Fuel cells which comprise as essential elements a fuel electrode, an oxidizing electrode, and an electrolyte between said electrodes are devices for the direct production of electricity through the electrochemical combustion of a fuel and oxidant. These devices are recognized for their high efficiency as energy conversion units, since unlike conventional combustion engines, they are not subject to the limitations of the Carnot heat cycle. It is the primary object of the present invention to provide an electrode having high electrochemical activity for an electrochemical cell. It is another object of the present invention to provide an electrode having an electro-catalyst which is highly resistant to the corrosive environment of an electrochemical cell.

  14. Recent Advances in Pt Monolayer Electrocatalysts for Oxygen Reduction Reaction: Scale-up Synthesis, Structure, and Activity of Pt Shells on Pd Cores

    SciTech Connect (OSTI)

    Sasaki, K.; Wang, J.X.; Naohara, H.; Marinkovic, N.; More, Karren Leslie; Inada, H.; Adzic, R.R.

    2010-01-01

    We have established a scale-up synthesis method to produce gram-quantities of Pt monolayer electrocatalysts. The core-shell structure of the Pt/Pd/C electrocatalyst has been verified using the HAADF-STEM Z-contrast images, STEM/EELS, and STEM/EDS line profile analysis. The atomic structure of this electrocatalyst and formation of a Pt monolayer on Pd nanoparticle surfaces were examined using in situ EXAFS. The Pt mass activity of the Pt/Pd/C electrocatalyst for ORR is considerably higher than that of commercial Pt/C electrocatalysts. The results with Pt monolayer electrocatalysts may significantly impact science of electrocatalysis and fuel-cell technology, as they have demonstrated an exceptionally effective way of using Pt that can resolve problems of other approaches, including electrocatalysts inadequate activity and high Pt content.

  15. Synthesis of Pd9Ru@Pt nanoparticles for oxygen reduction reaction in acidic electrolytes

    SciTech Connect (OSTI)

    Sun, Yu; Hsieh, Yu -Chi; Chang, Li -Chung; Wu, Pu -Wei; Lee, Jyh -Fu

    2014-11-22

    Nanoparticles of PdRu, Pd?Ru, and Pd?Ru are synthesized and impregnated on carbon black via a wet chemical reflux process. X-ray diffraction patterns of the as-synthesized samples, PdxRu/C (x=1/3/9), suggest succesful formation of alloy without presence of individual Pd and Ru nanoparticles. Images from transmission electron microscope confirm irregularly-shaped nanoparticles with average size below 3 nm. Analysis from extended X-ray absorption fine structure on both Pd and Ru K-edge absorption profiles indicate the Ru atoms are enriched on the surface of PdxRu/C. Among these samples, the Pd?Ru/C exhibits the strongest electrocatalytic activity for oxygen reduction reaction (ORR) in an oxygen-saturated 0.1 M aqueous HClO? solution. Subsequently, the Pd?Ru/C undegoes Cu under potential deposition, followed by a galvanic displacement reaction to deposit a Pt monolayer on the Pd?Ru surface (Pd?Ru@Pt). The Pd?Ru@Pt reveals better ORR performance than that of Pt, reaching a mass activity of 0.38 mA ?g? Pt, as compared to that of commercially available Pt nanoparticles (0.107 mA ?g? Pt). Thus, the mechanisms responsible for the ORR enhancement are attributed to the combined effects of lattice strain and ligand interaction. In addition, this core-shell Pd?Ru@Pt electrocatalyst represents a substantial reduction in the amount of Pt consumption and raw material cost.

  16. Monodisperse core/shell Ni/FePt nanoparticles and their con-version to Ni/Pt to catalyze oxygen reduction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Sen; Hao, Yizhou; Su, Dong; Doan-Nguyen, Vicky V. T.; Wu, Yaoting; Li, Jing; Sun, Shouheng; Murray, Christopher B.

    2014-10-28

    We report a size-controllable synthesis of monodisperse core/shell Ni/FePt nanoparticles (NPs) via a seed-mediated growth and their subsequent conversion to Ni/Pt NPs. Preventing surface oxidation of the Ni seeds is essential for the growth of uniform FePt shells. These Ni/FePt NPs have a thin (≈ 1 nm) FePt shell, and can be converted to Ni/Pt by acetic acid wash to yield active catalysts for oxygen reduction reaction (ORR). Tuning the core size allow for optimization of their electrocatalytic activity. The specific activity and mass activity of 4.2 nm/0.8 nm core/shell Ni/FePt reach 1.95 mA/cm² and 490 mA/mgPt at 0.9 Vmore » (vs. reversible hydrogen electrode, RHE), which are much higher than those of benchmark commercial Pt catalyst (0.34 mA/cm² and 92 mA/mgPt at 0.9 V). Our studies provide a robust approach to monodisperse core/shell NPs with non-precious metal core, making it possible to develop advanced NP catalysts with ultralow Pt content for ORR and many other heterogeneous reactions.« less

  17. Monodisperse core/shell Ni/FePt nanoparticles and their con-version to Ni/Pt to catalyze oxygen reduction

    SciTech Connect (OSTI)

    Zhang, Sen; Hao, Yizhou; Su, Dong; Doan-Nguyen, Vicky V. T.; Wu, Yaoting; Li, Jing; Sun, Shouheng; Murray, Christopher B.

    2014-10-28

    We report a size-controllable synthesis of monodisperse core/shell Ni/FePt nanoparticles (NPs) via a seed-mediated growth and their subsequent conversion to Ni/Pt NPs. Preventing surface oxidation of the Ni seeds is essential for the growth of uniform FePt shells. These Ni/FePt NPs have a thin (≈ 1 nm) FePt shell, and can be converted to Ni/Pt by acetic acid wash to yield active catalysts for oxygen reduction reaction (ORR). Tuning the core size allow for optimization of their electrocatalytic activity. The specific activity and mass activity of 4.2 nm/0.8 nm core/shell Ni/FePt reach 1.95 mA/cm² and 490 mA/mgPt at 0.9 V (vs. reversible hydrogen electrode, RHE), which are much higher than those of benchmark commercial Pt catalyst (0.34 mA/cm² and 92 mA/mgPt at 0.9 V). Our studies provide a robust approach to monodisperse core/shell NPs with non-precious metal core, making it possible to develop advanced NP catalysts with ultralow Pt content for ORR and many other heterogeneous reactions.

  18. Monodisperse core/shell Ni/FePt nanoparticles and their con-version to Ni/Pt to catalyze oxygen reduction

    SciTech Connect (OSTI)

    Zhang, Sen; Su, Dong; Doan-Nguyen, Vicky V. T.; Wu, Yaoting; Li, Jing; Sun, Shouheng; Murray, Christopher B.; Hao, Yizhou

    2014-11-12

    We report a size-controllable synthesis of monodisperse core/shell Ni/FePt nanoparticles (NPs) via a seed-mediated growth and their subsequent conversion to Ni/Pt NPs. Preventing surface oxidation of the Ni seeds is essential for the growth of uniform FePt shells. These Ni/FePt NPs have a thin (? 1 nm) FePt shell, and can be converted to Ni/Pt by acetic acid wash to yield active catalysts for oxygen reduction reaction (ORR). Tuning the core size allow for optimization of their electrocatalytic activity. The specific activity and mass activity of 4.2 nm/0.8 nm core/shell Ni/FePt reach 1.95 mA/cm and 490 mA/mgPt at 0.9 V (vs. reversible hydrogen electrode, RHE), which are much higher than those of benchmark commercial Pt catalyst (0.34 mA/cm and 92 mA/mgPt at 0.9 V). Our studies provide a robust approach to monodisperse core/shell NPs with non-precious metal core, making it possible to develop advanced NP catalysts with ultralow Pt content for ORR and many other heterogeneous reactions.

  19. Relating adatom emission to improved durability of Pt-Pd diesel oxidation catalysts

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Johns, Tyne Richele; Goeke, Ronald S.; Ashbacher, Valerie; Thune, Peter C.; Niemantsverdriet, J. W.; Kiefer, Boris; Kim, Chang H.; Balogh, Michael P.; Datye, Abhaya K.

    2015-06-05

    Sintering of nanoparticles is an important contributor to loss of activity in heterogeneous catalysts, such as those used for controlling harmful emissions from automobiles. But mechanistic details, such as the rates of atom emission or the nature of the mobile species, remain poorly understood. Herein we report a novel approach that allows direct measurement of atom emission from nanoparticles. We use model catalyst samples and a novel reactor that allows the same region of the sample to be observed after short-term heat treatments (seconds) under conditions relevant to diesel oxidation catalysts (DOCs). Monometallic Pd is very stable and does notmore » sinter when heated in air (T ≤ 800 °C). Pt sinters readily in air, and at high temperatures (≥800 °C) mobile Pt species emitted to the vapor phase cause the formation of large, faceted particles. In Pt–Pd nanoparticles, Pd slows the rate of emission of atoms to the vapor phase due to the formation of an alloy. However, the role of Pd in Pt DOCs in air is quite complex: at low temperatures, Pt enhances the rate of Pd sintering (which otherwise would be stable as an oxide), while at higher temperature Pd helps to slow the rate of Pt sintering. DFT calculations show that the barrier for atom emission to the vapor phase is much greater than the barrier for emitting atoms to the support. Thus, vapor-phase transport becomes significant only at high temperatures while diffusion of adatoms on the support dominates at lower temperatures.« less

  20. Relating adatom emission to improved durability of Pt-Pd diesel oxidation catalysts

    SciTech Connect (OSTI)

    Johns, Tyne Richele; Goeke, Ronald S.; Ashbacher, Valerie; Thune, Peter C.; Niemantsverdriet, J. W.; Kiefer, Boris; Kim, Chang H.; Balogh, Michael P.; Datye, Abhaya K.

    2015-06-05

    Sintering of nanoparticles is an important contributor to loss of activity in heterogeneous catalysts, such as those used for controlling harmful emissions from automobiles. But mechanistic details, such as the rates of atom emission or the nature of the mobile species, remain poorly understood. Herein we report a novel approach that allows direct measurement of atom emission from nanoparticles. We use model catalyst samples and a novel reactor that allows the same region of the sample to be observed after short-term heat treatments (seconds) under conditions relevant to diesel oxidation catalysts (DOCs). Monometallic Pd is very stable and does not sinter when heated in air (T ≤ 800 °C). Pt sinters readily in air, and at high temperatures (≥800 °C) mobile Pt species emitted to the vapor phase cause the formation of large, faceted particles. In Pt–Pd nanoparticles, Pd slows the rate of emission of atoms to the vapor phase due to the formation of an alloy. However, the role of Pd in Pt DOCs in air is quite complex: at low temperatures, Pt enhances the rate of Pd sintering (which otherwise would be stable as an oxide), while at higher temperature Pd helps to slow the rate of Pt sintering. DFT calculations show that the barrier for atom emission to the vapor phase is much greater than the barrier for emitting atoms to the support. Thus, vapor-phase transport becomes significant only at high temperatures while diffusion of adatoms on the support dominates at lower temperatures.

  1. Synthesis of Pd9Ru@Pt nanoparticles for oxygen reduction reaction in acidic electrolytes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sun, Yu; Hsieh, Yu -Chi; Chang, Li -Chung; Wu, Pu -Wei; Lee, Jyh -Fu

    2014-11-22

    Nanoparticles of PdRu, Pd₃Ru, and Pd₉Ru are synthesized and impregnated on carbon black via a wet chemical reflux process. X-ray diffraction patterns of the as-synthesized samples, PdxRu/C (x=1/3/9), suggest succesful formation of alloy without presence of individual Pd and Ru nanoparticles. Images from transmission electron microscope confirm irregularly-shaped nanoparticles with average size below 3 nm. Analysis from extended X-ray absorption fine structure on both Pd and Ru K-edge absorption profiles indicate the Ru atoms are enriched on the surface of PdxRu/C. Among these samples, the Pd₉Ru/C exhibits the strongest electrocatalytic activity for oxygen reduction reaction (ORR) in an oxygen-saturated 0.1more » M aqueous HClO₄ solution. Subsequently, the Pd₉Ru/C undegoes Cu under potential deposition, followed by a galvanic displacement reaction to deposit a Pt monolayer on the Pd₉Ru surface (Pd₉Ru@Pt). The Pd₉Ru@Pt reveals better ORR performance than that of Pt, reaching a mass activity of 0.38 mA μg⁻¹ Pt, as compared to that of commercially available Pt nanoparticles (0.107 mA μg⁻¹ Pt). Thus, the mechanisms responsible for the ORR enhancement are attributed to the combined effects of lattice strain and ligand interaction. In addition, this core-shell Pd₉Ru@Pt electrocatalyst represents a substantial reduction in the amount of Pt consumption and raw material cost.« less

  2. Surface segregation effects in electrocatalysis: Kinetics ofoxygen reduction reaction on polycrystalline Pt3Ni alloy surfaces

    SciTech Connect (OSTI)

    Stamenkovic, V.; Schmidt, T.J.; Ross, P.N.; Markovic, N.M.

    2002-11-01

    Effects of surface segregation on the oxygen reduction reaction (ORR) have been studied on a polycrystalline Pt3Ni alloy in acid electrolyte using ultra high vacuum (UHV) surface sensitive probes and the rotating ring disk electrode (RRDE) method. Preparation, modification and characterization of alloy surfaces were done in ultra high vacuum (UHV). Depending on the preparation method, two different surface compositions of the Pt3Ni alloy are produced: a sputtered surface with 75 % Pt and an annealed surface (950 K ) with 100 % Pt. The latter surface is designated as the 'Pt-skin' structure, and is a consequence of surface segregation, i.e., replacement of Ni with Pt atoms in the first few atomic layers. Definitive surface compositions were established by low energy ion scattering spectroscopy (LEISS). The cyclic voltammetry of the 'Pt-skin' surface as well as the pseudocapacitance in the hydrogen adsorption/desorption potential region is similar to a polycrystalline Pt electrode. Activities of ORR on Pt3Ni alloy surfaces were compared to polycrystalline Pt in 0.1M HClO4 electrolyte for the observed temperature range of 293 < T < 333 K. The order of activities at 333 K was: 'Pt-skin' > Pt3Ni (75% Pt) > Pt with the maximum catalytic enhancement obtained for the 'Pt-skin' being 4 times that for pure Pt. Catalytic improvement of the ORR on Pt3Ni and 'Pt-skin' surfaces was assigned to the inhibition of Pt-OHad formation (on Pt sites) versus polycrystalline Pt. Production of H2O2 on both surfaces were similar compared to the pure Pt. Kinetic analyses of RRDE data confirmed that kinetic parameters for the ORR on the Pt3Ni and 'Pt-skin' surfaces are the same as on pure Pt: reaction order, m=1, two identical Tafel slopes, activation energy, {approx} 21-25 kJ/mol. Therefore the reaction mechanism on both Pt3Ni and 'Pt-skin' surfaces is the same as one proposed for pure Pt i.e. 4e{sup -} reduction pathway.

  3. Electronic and structural influence of Ni by Pd substitution on the hydrogenation properties of TiNi

    SciTech Connect (OSTI)

    Emami, Hoda; Souques, Raphaeel; Crivello, Jean-Claude; Cuevas, Fermin

    2013-02-15

    In Ti (Ni,Pd) compounds, the hydrogen capacity and the stability of their hydrides decreases when Ni is partially substituted by larger in size Pd atoms. To understand this peculiar behaviour, the crystal structure of TiNi{sub 1-x}Pd{sub x}D{sub y} (x=0.1, 0.3 and 0.5) deuterides and the stability of TiNi{sub 1-x}Pd{sub x} (0{<=}x{<=}0.5) intermetallics and their hydrides have been investigated by both neutron diffraction experiments and Density Functional Theory (DFT) calculations. Neutron diffraction shows that at x=0.1 and 0.3, deuterium absorption induces tetragonal distortion in intermetallics sublattice whereas at x=0.5 the cubic symmetry is preserved. The structural properties and the heat of formation of TiNi{sub 1-x}Pd{sub x} (0{<=}x{<=}0.5) intermetallics and their hydrides have been determined by DFT. These results show that Pd substitution increases the stability of the intermetallics and decreases the stability of the hydrides, which confirms the rule of reverse stability. - Graphical abstract: Crystal structure of Ti(Ni,Pd)Hy hydrides in the I4/mmm space group. Highlights: Black-Right-Pointing-Pointer Neutron Diffraction and DFT calculations have been done on TiNi{sub 1-x}Pd{sub x}H{sub y} compounds. Black-Right-Pointing-Pointer Electronic effect of Pd substitution governs the hydrogenation properties in TiNi. Black-Right-Pointing-Pointer The rule of reverse stability in intermetallics/hydrides is observed with Pd substitution. Black-Right-Pointing-Pointer The hydrogen atoms in the I4/mmm structure prefer to occupy the 16n site.

  4. Enhanced Dry Reforming of Methane on Ni and Ni-Pt Catalysts Synthesized by Atomic Layer Deposition

    SciTech Connect (OSTI)

    Gould, Troy D.; Montemore, Matthew M.; Lubers, Alia M.; Ellis, Lucas D.; Weimer, Alan; Falconer, John L.; Medlin, James W.

    2015-02-25

    Atomic layer deposition (ALD) was used to deposit Ni and Pt on alumina supports to form monometallic and bimetallic catalysts with initial particle sizes of 12.4 nm. The ALD catalysts were more active (per mass of metal) than catalysts prepared by incipient wetness (IW) for dry reforming of methane (DRM), and they did not form carbon whiskers during reaction due to their sufficiently small size. Catalysts modified by Pt ALD had higher rates of reaction per mass of metal and inhibited coking, whereas NiPt catalysts synthesized by IW still formed carbon whiskers. Temperature-programmed reduction of Ni catalysts modified by Pt ALD indicated the presence of bimetallic interaction. Density functional theory calculations suggested that under reaction conditions, the NiPt surfaces form Ni-terminated surfaces that are associated with higher DRM rates (due to their C and O adsorption energies, as well as the CO formation and CH4 dissociation energies).

  5. Ultra-thin L1{sub 0}-FePt for perpendicular anisotropy L1{sub 0}-FePt/Ag/[Co/Pd]{sub 30} pseudo spin valves

    SciTech Connect (OSTI)

    Ho, Pin; Chow, Gan Moog; Chen, Jing-Sheng, E-mail: msecj@nus.edu.sg [Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore); Han, Guchang [Data Storage Institute, Agency of Science, Technology and Research (A-STAR), Singapore 117608 (Singapore); He, Kaihua [School of Mathematics and Physics, China University of Geosciences, Wuhan 430074 (China)

    2014-05-07

    Perpendicular anisotropy L1{sub 0}-FePt/Ag/[Co/Pd]{sub 30} pseudo spin valves (PSVs) with ultra-thin L1{sub 0}-FePt alloy free layer possessing high anisotropy and thermal stability have been fabricated and studied. The thickness of the L1{sub 0}-FePt layer was varied between 2 and 4?nm. The PSV became increasingly decoupled with reduced L1{sub 0}-FePt thickness due to the larger difference between the coercivity of the L1{sub 0}-FePt and [Co/Pd]{sub 30} films. The PSV with an ultra-thin L1{sub 0}-FePt free layer of 2?nm displayed a high K{sub u} of 2.21??10{sup 7}?ergs/cm{sup 3}, high thermal stability of 84 and a largest giant magnetoresistance of 0.54%.

  6. Enhanced electrocatalytic activity and stability of Pd3V/C nanoparticles with a trace amount of Pt decoration for the oxygen reduction reaction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Sufen; Han, Lili; Zhu, Jing; Xiao, Weiping; Wang, Jie; Liu, Hongfang; Xin, Huolin; Wang, Deli

    2015-09-14

    In this study, carbon supported Pd3V bimetallic alloy nanoparticles (Pd3V/C) have been successfully synthesized via a simple impregnation–reduction method, followed by high temperature treatment under a H2 atmosphere. Electrochemical tests reveal that the half-wave potential of Pd3V/C-500 shifts positively 40 mV compared with Pd/C. However, the catalytic activity of Pd3V/C-500 suffers from serious degradation after 1k cycles. By a spontaneous displacement reaction or co-reduction method, a trace amount of Pt was decorated on the surface or inside of the Pd3V/C nanoparticles. The catalytic activity and stability of the Pd3V@Pt/C and Pt-Pd3V/C catalysts for the oxygen reduction reaction (ORR) are enhancedmore » significantly, and are comparable to commercial Pt/C. In addition, the Pt mass activity of Pd3V@Pt/C and Pt-Pd3V/C improves by factors of 10.9 and 6.5 at 0.80 V relative to Pt/C. Moreover, Pt-decorated Pd3V/C nanoparticles show almost no obvious morphology change after durability tests, because the Pt-rich shell plays an important role in preventing degradation.« less

  7. Effects of aging on the characteristics of TiNiPd shape memory alloy thin films

    SciTech Connect (OSTI)

    Zhang Congchun

    2008-07-15

    TiNiPd thin films have been deposited on glass substrate using R.F. magnetron sputtering. Effects of annealing and aging on the microstructure, phase transformation behaviors and shape memory effects of these thin films have been studied by X-ray diffractometry, differential scanning calorimeter, tensile tests and internal friction characteristics. The TiNiPd thin films annealed at 750 deg. C exhibit uniform martensite/austenite transformations and shape memory effect. Aging at 450 deg. C for 1 h improved the uniformity of transformations and shape memory effect. Long time aging decreased transformation temperatures and increased the brittleness of TiNiPd thin films.

  8. Deep oxidation of methane on particles derived from YSZ-supported Pd-Pt-(O) coatings synthesized by pulsed filtered cathodic arc

    SciTech Connect (OSTI)

    Horwat, D.; Endrino, J.L.; Boreave, A.; Karoum,R.; Pierson, J.F.; Weber, S.; Anders, A.; Vernoux, Ph.

    2008-12-12

    Methane conversion tests were performed on Pd, PdOy, Pd0.6Pt0.4Oy and Pd0.4Pt0.6Oy thin films deposited on yttria stabilized zirconia (YSZ) substrates. Pt containing films exhibited poor activity and high reducibility. As-deposited Pd and PdOy films showed good activity and transformed, during the cycling process, to particles dispersed on the YSZ substrates. The higher reaction rate of initially PdOy films was explained by a better dispersion of the catalyst. A drop of the reaction rate was observed when the temperature exceeded 735oC and 725oC for initially Pd and PdOy, respectively, which can be associated with the high-temperature reduction of PdO into Pd.

  9. Correlating Extent of PtNi Bond Formation with Low-temperature Hydrogenation of Benzene and 1,3-butadiene over Supported Pt/Ni Bimetallic Catalysts

    SciTech Connect (OSTI)

    Lonergan, W.; Vlachos, D; Chen, J

    2010-01-01

    Low-temperature hydrogenation of benzene and 1,3-butadiene on supported Pt/Ni catalysts have been used as probe reactions to correlate hydrogenation activity with the extent of Pt-Ni bimetallic bond formation. Pt/Ni bimetallic and Pt and Ni monometallic catalysts were supported on {gamma}-Al{sub 2}O{sub 3} using incipient wetness impregnation. Two sets of bimetallic catalysts were synthesized: one set to study the effect of metal atomic ratio and the other to study the effect of impregnation sequence. Fourier transform infrared spectroscopy (FTIR) CO adsorption studies were performed to characterize the surface composition of the bimetallic nanoparticles, and transmission electron microscopy (TEM) was utilized to characterize the particle size distribution. Batch reactor studies with FTIR demonstrated that all bimetallic catalysts outperformed monometallic catalysts for both benzene and 1,3-butadiene hydrogenation. Within the two sets of bimetallic catalysts, it was found that catalysts with a smaller Pt:Ni ratio possessed higher hydrogenation activity and that catalysts synthesized using co-impregnation had greater activity than sequentially impregnated catalysts. Extended X-ray absorption fine structure (EXAFS) measurements were performed in order to verify the extent of Pt-Ni bimetallic bond formation, which was found to correlate with the hydrogenation activity.

  10. Gram-Scale Synthesized Pd2Co-Supported PtMonolayers Electrocatalysts for Oxygen Reduction Reaction

    SciTech Connect (OSTI)

    Zhou, W.P.; Sasaki, K.; Su, D.; Zhu, Y.; Wang, J.X.; Adzic, R.R.

    2010-04-21

    Gram-scale synthesis of Pt{sub ML} electrocatalysts with a well-defined core-shell structure has been carried out using method involving galvanic displacement of an underpotential deposition Cu layer. The Pt shell thickness can be controlled by stepwise deposition. The Pt{at}Pd{sub 2}Co/C nanoparticles were characterized by X-ray powder diffraction, aberration-corrected scanning transmission electron microscopy, high-resolution energy-loss spectrometry, and in situ X-ray absorption spectroscopy. A complete Pt shell of 0.6 nm on a Pd{sub 2}Co core has been confirmed. The Pt{at}Pd{sub 2}Co/C core-shell electrocatalysts showed a very high activity for the oxygen reduction reaction; the Pt mass and specific activity were 0.72 A mg{sup -1}{sub Pt} and 0.5 mA cm{sup -2}, respectively (3.5 and 2.5 times higher than the corresponding values for commercial Pt catalysts), at 0.9 V in 0.1 M HClO{sub 4} at room temperature. In an accelerated potential cycling test, a loss in active surface area and a decrease in catalytic activity for gram-scale-synthesized Pt{sub ML} catalysts were also determined.

  11. Tunable magnetization dynamics in disordered FePdPt ternary alloys: Effects of spin orbit coupling

    SciTech Connect (OSTI)

    Ma, L.; Fan, W. J. Chen, F. L.; Zhou, S. M.; Li, S. F.; Lai, T. S.; He, P.; Xu, X. G.; Jiang, Y.

    2014-09-21

    The magnetization dynamics of disordered Fe₀.₅(Pd{sub 1–x}Pt{sub x})₀.₅ alloy films was studied by time-resolved magneto-optical Kerr effect and ferromagnetic resonance. The intrinsic Gilbert damping parameter α₀ and the resonance linewidth change linearly with the Pt atomic concentration. In particular, the induced in-plane uniaxial anisotropy constant K{sub U} also increases for x increasing from 0 to 1. All these results can be attributed to the tuning effect of the spin orbit coupling. For the disordered ternary alloys, an approach is proposed to control the induced in-plane uniaxial anisotropy, different from conventional thermal treat methods, which is helpful to design and fabrications of spintronic devices.

  12. Recent Advances in Platinum Monolayer Electrocatalysts for Oxygen Reduction Reaction: Scale-up Synthesis Structure and Activity of Pt Shells on Pd Cores

    SciTech Connect (OSTI)

    Sasaki K.; Wang J.X.; Naohara H.; Marinkovic N.; More K.; Inada H.; Adzic R.R.

    2010-03-01

    We have established a scale-up synthesis method to produce gram-quantities of Pt monolayer electrocatalysts. The core-shell structure of the Pt/Pd/C electrocatalyst has been verified using the HAADF-STEM Z-contrast images, STEM/EELS, and STEM/EDS line profile analysis. The atomic structure of this electrocatalyst and formation of a Pt monolayer on Pd nanoparticle surfaces were examined using in situ EXAFS. The Pt mass activity of the Pt/Pd/C electrocatalyst for ORR is considerably higher than that of commercial Pt/C electrocatalysts. The results with Pt monolayer electrocatalysts may significantly impact science of electrocatalysis and fuel-cell technology, as they have demonstrated an exceptionally effective way of using Pt that can resolve problems of other approaches, including electrocatalysts inadequate activity and high Pt content.

  13. A Study on a Tritium Separation Process Using Self-Developing Gas Chromatography with Pd-Pt Alloy

    SciTech Connect (OSTI)

    Kojima, S.; Yokosawa, M.; Matsuyama, M.; Numata, M.; Kato, T.; Watanabe, K.

    2005-07-15

    To study the practical application of a tritium separation process using Self-Developing Gas Chromatography (SDGC) using a Pd-Pt alloy, intermediate scale-up experiments (22 mm ID x 2 m length column) and the development of a computational simulation method have been conducted. In addition, intermediate scale production of Pd-Pt powder has been developed for the scale-up experiments.The following results were obtained: (1) a 50-fold scale-up from 3 mm to 22 mm causes no significant impact on the SDGC process; (2) the Pd-Pt alloy powder is applicable to a large size SDGC process; and (3) the simulation enables preparation of a conceptual design of a SDGC process for tritium separation.

  14. Enhanced electrocatalytic activity and stability of Pd3V/C nanoparticles with a trace amount of Pt decoration for the oxygen reduction reaction

    SciTech Connect (OSTI)

    Liu, Sufen; Han, Lili; Zhu, Jing; Xiao, Weiping; Wang, Jie; Liu, Hongfang; Xin, Huolin; Wang, Deli

    2015-09-14

    In this study, carbon supported Pd3V bimetallic alloy nanoparticles (Pd3V/C) have been successfully synthesized via a simple impregnation–reduction method, followed by high temperature treatment under a H2 atmosphere. Electrochemical tests reveal that the half-wave potential of Pd3V/C-500 shifts positively 40 mV compared with Pd/C. However, the catalytic activity of Pd3V/C-500 suffers from serious degradation after 1k cycles. By a spontaneous displacement reaction or co-reduction method, a trace amount of Pt was decorated on the surface or inside of the Pd3V/C nanoparticles. The catalytic activity and stability of the Pd3V@Pt/C and Pt-Pd3V/C catalysts for the oxygen reduction reaction (ORR) are enhanced significantly, and are comparable to commercial Pt/C. In addition, the Pt mass activity of Pd3V@Pt/C and Pt-Pd3V/C improves by factors of 10.9 and 6.5 at 0.80 V relative to Pt/C. Moreover, Pt-decorated Pd3V/C nanoparticles show almost no obvious morphology change after durability tests, because the Pt-rich shell plays an important role in preventing degradation.

  15. Characterizations Of Precipitate Phases In a Ti-Ni-Pd Alloy

    SciTech Connect (OSTI)

    Yang, Fan; Kovarik, Libor; Phillips, Patrick J.; Noebe, Ronald D.; Mills, M. J.

    2012-06-01

    Precipitates in the Ti46Ni37.5Pd16.5 alloy were investigated by electron diffraction and high-resolution scanning transmission electron microscopy. The phase content and stability were determined at several different temperatures and times. Aging at 400 C for an hour results in a new phase, which is consumed by P-phase at longer aging time. At 450 C, the new phase appears first, and then coexists with P-phase. At 500 C, the entire alloy transformed into the new phase. At 550 C, Ti3(Ni,Pd)4 phase begins to form.

  16. A photoemission study of Pd ultrathin films on Pt(111) (Journal...

    Office of Scientific and Technical Information (OSTI)

    At sub-monolayer coverage of Pd thin films, the splitting of Pd 3d core level peaks ... on the Pd 3d vanishes and only the initial-state effect, a negative SCLS, is present. ...

  17. Bulk amorphous Pd{endash}Ni{endash}Fe{endash}P alloys: Preparation and characterization

    SciTech Connect (OSTI)

    Shen, T.D.; He, Y.; Schwarz, R.B. [Materials Science and Technology Division, MS K765, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1999-05-01

    Bulk amorphous alloys of Pd{sub x}Ni{sub y}Fe{sub 80{minus}x{minus}y}P{sub 20} (25{le}x{le}60, 20{le}y{le}55, x+y{ge}60) were prepared by a flux-melting and water-quenching method. Seven-mm diameter glassy rods of Pd{sub 40}Ni{sub 40{minus}x}Fe{sub x}P{sub 20} (0{le}x{le}20) were studied in greater detail. For these alloys, the difference between the crystallization and glass transition temperatures ranges from 102 K for x=0 to 53 K for x=20. In this composition range, the reduced glass transition temperature, T{sub rg}, ranges from 0.66 to 0.57. The change in density upon crystallization ranges from 0.24{plus_minus}0.04{percent} for x=0 to 1.33{plus_minus}0.24{percent} for x=10. The partial molar volume of Fe in amorphous Pd{sub 40}Ni{sub 40{minus}x}Fe{sub x}P{sub 20} alloys is significantly larger than the molar volume of (metastable) fcc Fe. This, as well as a comparison with the molar volumes of crystalline compounds, suggests chemically selective Fe{endash}Pd bonding in these glasses. {copyright} {ital 1999 Materials Research Society.}

  18. Rationalization of Au concentration and distribution in AuNi@Pt core-shell nanoparticles for oxygen reduction reaction

    SciTech Connect (OSTI)

    An, Wei; Liu, Ping

    2015-09-18

    Improving the activity and stability of Pt-based coreshell nanocatalysts for proton exchange membrane fuel cells while lowering Pt loading has been one of the big challenges in electrocatalysis. Here, using density functional theory, we report the effect of adding Au as the third element to enhance the durability and activity of Ni@Pt coreshell nanoparticles (NPs) during the oxygen reduction reaction (ORR). Our results show that the durability and activity of a Ni@Pt NP can be finely tuned by controlling Au concentration and distribution. For a NiAu@Pt NP, the durability can be greatly promoted by thermodynamically favorable segregation of Au to replace the Pt atoms at vertex, edge, and (100) facets on the shell, while still keeping the ORR activity on the active Pt(111) shell as high as that of Ni@Pt nanoparticles. Such behavior strongly depends on a direct interaction with the Ni interlayer. The results not only highlight the importance of interplay between surface strain on the shell and the interlayershell interaction in determining the durability and activity but also provide guidance on how to maximize the usage of Au to optimize the performance of coreshell (Pt) nanoparticles. As a result, such understanding has allowed us to discover a novel NiAu@Pt nanocatalyst for the ORR.

  19. Rationalization of Au concentration and distribution in AuNi@Pt core-shell nanoparticles for oxygen reduction reaction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    An, Wei; Liu, Ping

    2015-09-18

    Improving the activity and stability of Pt-based core–shell nanocatalysts for proton exchange membrane fuel cells while lowering Pt loading has been one of the big challenges in electrocatalysis. Here, using density functional theory, we report the effect of adding Au as the third element to enhance the durability and activity of Ni@Pt core–shell nanoparticles (NPs) during the oxygen reduction reaction (ORR). Our results show that the durability and activity of a Ni@Pt NP can be finely tuned by controlling Au concentration and distribution. For a NiAu@Pt NP, the durability can be greatly promoted by thermodynamically favorable segregation of Au tomore » replace the Pt atoms at vertex, edge, and (100) facets on the shell, while still keeping the ORR activity on the active Pt(111) shell as high as that of Ni@Pt nanoparticles. Such behavior strongly depends on a direct interaction with the Ni interlayer. The results not only highlight the importance of interplay between surface strain on the shell and the interlayer–shell interaction in determining the durability and activity but also provide guidance on how to maximize the usage of Au to optimize the performance of core–shell (Pt) nanoparticles. As a result, such understanding has allowed us to discover a novel NiAu@Pt nanocatalyst for the ORR.« less

  20. Interdiffusion Behavior of Pt-Diffused gamma+gamma' Coatings on Ni-Based Superalloys

    SciTech Connect (OSTI)

    Zhang, Ying; Stacy, J P; Pint, Bruce A; Haynes, James A; Hazel, Brian T; Nagaraj, Ben

    2008-01-01

    Platinum-diffused {gamma} + {gamma}{prime} coatings ({approx} 20 at.% Al, {approx} 22 at.% Pt) were synthesized on Rene 142 and Rene N5 Ni-based superalloys by electroplating the substrates with {approx} 7 {micro}m of Pt, followed by an annealing treatment in vacuum at 1175 C. In order to study the compositional and microstructural evolution of these coatings at elevated temperatures, interdiffusion experiments were carried out on coated specimens in the temperature range of 900-1050 C for various durations. Composition profiles of the alloying elements in the {gamma} + {gamma}{prime} coatings before and after diffusion experiments were determined by electron probe microanalysis. Although the change of the Al content in the coatings was minimal under these interdiffusion conditions, the decrease of the Pt content and increase of the diffusion depth of Pt into the substrate alloys were significant. A preliminary diffusion model was used to estimate the Pt penetration depth after diffusion.

  1. Pt and Pd catalyzed oxidation of Li2O2 and DMSO during Li–O2 battery charging

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gittleson, Forrest S.; Ryu, Won-Hee; Schwab, Mark; Tong, Xiao; Taylor, André D.

    2016-01-01

    Rechargeable Li-O2 and Li-air batteries require electrode and electrolyte materials that synergistcally promote long-term cell operation. We investigate the role of noble metals Pt and Pd as catalysts for the Li-O2 oxidation process and their compatibility with a dimethyl sulfoxide (DMSO) based electrolyte. Lastly, we identify a basis for low potential Li2O2 evolution followed by oxidative decomposition of the electrolyte to form carbonate side products.

  2. Activity and Evolution of Vapor Deposited Pt-Pd Oxygen Reduction Catalysts for Solid Acid Fuel Cells

    SciTech Connect (OSTI)

    Papandrew, Alexander B; Chisholm, Calum R; Zecevic, strahinja; Veith, Gabriel M; Zawodzinski, Thomas A

    2013-01-01

    The performance of hydrogen fuel cells based on the crystalline solid proton conductor CsH2PO4 is circumscribed by the mass activity of platinum oxygen reduction catalysts in the cathode. Here we report on the first application of an alloy catalyst in a solid acid fuel cell, and demonstrate an activity 4.5 times greater than Pt at 0.8 V. These activity enhancements were obtained with platinum-palladium alloys that were vapor-deposited directly on CsH2PO4 at 210 C. Catalyst mass activity peaks at a composition of 84 at% Pd, though smaller activity enhancements are observed for catalyst compositions exceeding 50 at% Pd. Prior to fuel cell testing, Pd-rich catalysts display lattice parameter expansions of up to 2% due to the presence of interstitial carbon. After fuel cell testing, a Pt-Pd solid solution absent of lattice dilatation and depleted in carbon is recovered. The structural evolution of the catalysts is correlated with catalyst de-activation.

  3. Bulk glass formation in the Pd{endash}Ni{endash}P system

    SciTech Connect (OSTI)

    He, Y.; Schwarz, R.B.; Archuleta, J.I. [Center for Materials Science, MS K-765, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Center for Materials Science, MS K-765, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1996-09-01

    Bulk amorphous Pd{endash}Ni{endash}P rods with diameters ranging from 10 to 25 mm were prepared by a fluxing technique over a wide composition range. For most bulk glassy alloys studied, the difference between the glass transition temperature and the crystallization temperature, {ital T}{sub {ital x}}{minus}{ital T}{sub {ital g}}, is larger than 90 K. Of all the alloy compositions examined, Pd{sub 40}Ni{sub 40}P{sub 20} has the highest glass formability, and 300-g bulk amorphous cylinders, 25 mm in diameter and 50 mm in length, were easily and repeatedly formed. This size, however, is not an upper limit. The elastic properties of these bulk amorphous alloys were determined by a resonant ultrasound spectroscopy technique.

  4. Effect of Ag addition to L1{sub 0} FePt and L1{sub 0} FePd films grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Tokuoka, Y.; Seto, Y.; Kato, T.; Iwata, S.

    2014-05-07

    L1{sub 0} ordered FePt-Ag (5?nm) and FePd-Ag (5?nm) films were grown on MgO (001) substrate at temperatures of 250400?C by using molecular beam epitaxy method, and their crystal and surface structures, perpendicular magnetic anisotropies and Curie temperatures were investigated. In the case of FePt-Ag, Ag addition with the amount of 1020 at.?% was effective to promote L1{sub 0} ordering and granular growth, resulting in the increase of the perpendicular magnetic anisotropy and coercivity of the FePt-Ag films. On the other hand, in the case of FePd-Ag, Ag addition changed the surface morphology from island to continuous film associated with the reductions of its coercivity and perpendicular anisotropy. The variations of lattice constants and Curie temperature with Ag addition were significantly different between FePt-Ag and FePd-Ag. For FePd-Ag, the c and a axes lattice spacings and Curie temperature gradually changed with increasing Ag content, while they unchanged for FePt-Ag. These results suggest the possibility of the formation of FePdAg alloy in FePd-Ag, while Ag segregation in FePt-Ag.

  5. Tuning magnetotransport in PdPt/Y{sub 3}Fe{sub 5}O{sub 12}: Effects of magnetic proximity and spin-orbit coupling

    SciTech Connect (OSTI)

    Zhou, X.; Ma, L.; Shi, Z.; Zhou, S. M.; Guo, G. Y.; Hu, J.; Wu, R. Q.

    2014-07-07

    We report that anisotropic magnetoresistance (AMR) and anomalous Hall conductivity (AHC) in the Pd{sub 1−x}Pt{sub x}/Y{sub 3}Fe{sub 5}O{sub 12} (YIG) bilayers could be tuned by varying the Pt concentration (x) and also temperature (T). In particular, the AHC at low T changes its sign when x increases from 0 to 1, agreeing with the negative and positive AHC predicted by our ab initio calculations for the magnetic proximity (MP)-induced ferromagnetic Pd and Pt, respectively. The AMR ratio is enhanced by ten times when x increases from 0 to 1. Furthermore, the AMR of PdPt/YIG bilayers shows similar T-dependence as the magnetic susceptibility of the corresponding bulk Pd/Pt, also indicating the MP effect as the origin of the AMR. The present work demonstrates that the alloying of Pt and Pd not only offers tunable spin-orbit coupling but also is useful to reveal the nature of the AMR and AHC in Pt/YIG bilayers, which are useful for spintronics applications.

  6. Synthesis and characterization of NiFe{sub 2}O{sub 4}Pd magnetically recyclable catalyst for hydrogenation reaction

    SciTech Connect (OSTI)

    Karao?lu, E.; zel, U.; Caner, C.; Baykal, A.; Summak, M.M.; Szeri, H.

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ? Novel superparamagnetic NiFe{sub 2}O{sub 4}Pd magnetically recyclable catalyst was fabricated through co-precipitation. ? It could be reused several times without significant loss in catalytic activity for hydrogenation reaction. ? No further modification of the NiFe{sub 2}O{sub 4}Pd magnetically recyclable catalyst is necessary for utilization as catalyst. -- Abstract: Herein we report the fabrication and characterization magnetically recyclable catalysts of NiFe{sub 2}O{sub 4}Pd nanocomposite as highly effective catalysts for reduction reactions in liquid phase. The reduction Pd{sup 2+} was accomplished with polyethylene glycol 400 (PEG-400) instead of sodium borohydride (NaBH{sub 4}) and NiFe{sub 2}O{sub 4} nanoparticles was prepared by sonochemically using FeCI{sub 3}6H{sub 2}O and NiCl{sub 2}. The chemical characterization of the product was done with X-ray diffractometry, Infrared spectroscopy, transmission electron microscopy, UVVis spectroscopy, thermal gravimetry and inductively coupled plasma. Thus formed NiFe{sub 2}O{sub 4}Pd MRCs showed a very high activity in reduction reactions of 4-nitro aniline and 1,3-dinitrobenzene in liquid phase. It was found out that the catalytic activity of NiFe{sub 2}O{sub 4}Pd MRCs on the reduction of 4-nitro aniline and 1,3-dinitrobenzene in liquid phase are between 9993% and 9893%, respectively. Magnetic character of this system allowed recovery and multiple use without significant loss of its catalytic activity. It is found that NiFe{sub 2}O{sub 4}Pd MRCs showed very efficient catalytic activity and multiple usability.

  7. Effect of electronic structures on catalytic properties of CuNi alloy and Pd in MeOH-related reactions

    SciTech Connect (OSTI)

    Tsai, An-Pang; Kimura, Tomofumi; Suzuki, Yukinori; Kameoka, Satoshi; Shimoda, Masahiko; Ishii, Yasushi

    2013-04-14

    We investigated the catalytic properties of a CuNi solid solution and Pd for methanol-related reactions and associated valence electronic structures. Calculations and X-ray photoelectron spectroscopy measurements revealed that the CuNi alloy has a similar valence electronic structure to Pd and hence they exhibited similar CO selectivities in steam reforming of methanol and decomposition of methanol. Samples prepared by various processes were found to have similar CO selectivities. We conjecture that alloying of Cu and Ni dramatically alters the valence electronic structures, making it similar to that of Pd so that the alloy exhibits similar catalytic properties to Pd. First-principles slab calculations of surface electronic structures support this conjecture.

  8. Differentiation of O-H and C-H Bond Scission Mechanisms of Ethylene Glycol on Pt and Ni/Pt Using Theory and Isotopic Labeling Experiments

    SciTech Connect (OSTI)

    Salciccioli, Michael [Univ. of Delaware, Newark, DE (United States). Catalysis Center for Energy Innovation (CCEI) and Center for Catalytic Science and Technology (CCST); Yu, Weiting [Univ. of Delaware, Newark, DE (United States). Catalysis Center for Energy Innovation (CCEI) and Center for Catalytic Science and Technology (CCST); Barteau, Mark A. [Univ. of Delaware, Newark, DE (United States). Catalysis Center for Energy Innovation (CCEI) and Center for Catalytic Science and Technology (CCST); Chen, Jingguang G. [Univ. of Delaware, Newark, DE (United States). Catalysis Center for Energy Innovation (CCEI) and Center for Catalytic Science and Technology (CCST); Vlachos, Dionisios G. [Univ. of Delaware, Newark, DE (United States). Catalysis Center for Energy Innovation (CCEI) and Center for Catalytic Science and Technology (CCST)

    2011-05-25

    Understanding and controlling bond-breaking sequences of oxygenates on transition metal catalysts can greatly impact the utilization of biomass feedstocks for fuels and chemicals. The decomposition of ethylene glycol, as the simplest representative of biomass-derived polyols, was studied via density functional theory (DFT) calculations to identify the differences in reaction pathways between Pt and the more active Ni/Pt bimetallic catalyst. Comparison of the computed transition states indicated three potentially feasible paths from ethylene glycol to C1 oxygenated adsorbates on Pt. While not important on Pt, the pathway to 1,2-dioxyethylene (OCH?CH?O) is favored energetically on the Ni/Pt catalyst. Temperature-programmed desorption (TPD) experiments were conducted with deuterated ethylene glycols for comparison with DFT results. These experiments confirmed that decomposition of ethylene glycol on Pt proceeds via initial OH bond cleavage, followed by CH and the second OH bond cleavages, whereas on the Ni/Pt surface, both OH bonds are cleaved initially. The results are consistent with vibrational spectra and indicate that tuning of the catalyst surface can selectively control bond breaking. Finally, the significant mechanistic differences in decomposition of polyols compared to that of monoalcohols and hydrocarbons serve to identify general trends in bond scission sequences.

  9. Study of supported PtCu and PdAu bimetallic nanoparticles using in-situ x-ray tools.

    SciTech Connect (OSTI)

    Oxford, S. M.; Lee, P. L.; Chupas, P. J.; Chapman, K. W.; Kung, M. C.; Kung, H. H.; Northwestern Univ.

    2010-01-01

    A combination of two synchrotron X-ray techniques, X-ray absorption spectroscopy (XAS), and pair distribution function analysis (PDF) with complementary Fourier transform infrared (FTIR) spectroscopy measurement, was used to characterize the composition distributions of PdAu and PtCu bimetallic particles after treatment in H{sub 2} or CO and in the presence of these gases. This is the first reported application of PDF to the study of supported bimetallic nanoparticles. We found that XAS was informative in determining the component distribution of an initial sample, but PDF was better suited to following changes in the distribution upon changing the gas environment. Thus, the surface of a PtCu bimetallic particle of about 2.5 nm after treatment in H{sub 2} was found to be enriched in Cu, while the core was bimetallic. There was no evidence of a component-segregated core?shell structure. Treatment in CO caused enrichment of Pt to the surface layer, with a concomitant migration of Cu to the core. The average particle size remained the same. For the PdAu bimetallic particles, the surface and core compositions were similar after H{sub 2} treatment, and Pd was enriched in the surface after CO treatment. The X-ray results compared favorably to infrared spectroscopy results. The results demonstrated that the two X-ray techniques in combination can generate new information not available with either technique alone or other techniques, about the elemental distribution of bimetallic particles under conditions relevant to catalysis. They could provide new insight into structure-function relationships and time-on-stream behavior of bimetallic catalysts.

  10. Multi-functional ultrathin PdxCu1-x and Pt~PdxCu1-x one-dimensional nanowire motifs for various small molecule oxidation reactions

    SciTech Connect (OSTI)

    Liu, Haiqing; Wong, Stanislaus S.; Adzic, Radoslav R.

    2015-11-18

    Developing novel electrocatalysts for small molecule oxidation processes, including formic acid oxidation (FAOR), methanol oxidation reaction (MOR), and ethanol oxidation reaction (EOR), denoting the key anodic reactions for their respective fuel cell configurations, is a significant and relevant theme of recent efforts in the field. Herein, in this report, we demonstrated a concerted effort to couple and combine the benefits of small size, anisotropic morphology, and tunable chemical composition in order to devise a novel “family” of functional architectures. In particular, we have fabricated not only ultrathin 1-D Pd1–xCux alloys but also Pt-coated Pd1–xCux (i.e., Pt~Pd1–xCux; herein the ~ indicates an intimate association, but not necessarily actual bond formation, between the inner bimetallic core and the Pt outer shell) core–shell hierarchical nanostructures with readily tunable chemical compositions by utilizing a facile, surfactant-based, wet chemical synthesis coupled with a Cu underpotential deposition technique. Our main finding is that our series of as-prepared nanowires are functionally flexible. More precisely, we demonstrate that various examples within this “family” of structural motifs can be tailored for exceptional activity with all 3 of these important electrocatalytic reactions. In particular, we note that our series of Pd1–xCux nanowires all exhibit enhanced FAOR activities as compared with not only analogous Pd ultrathin nanowires but also commercial Pt and Pd standards, with Pd9Cu representing the “optimal” composition. Moreover, our group of Pt~Pd1–xCux nanowires consistently outperformed not only commercial Pt NPs but also ultrathin Pt nanowires by several fold orders of magnitude for both the MOR and EOR reactions in alkaline media. As a result, the variation of the MOR and EOR performance with

  11. Mechanical and functional behavior of high-temperature Ni-Ti-Pt shape memory alloys

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Buchheit, Thomas E.; Susan, Donald F.; Massad, Jordan E.; McElhanon, James R.; Noebe, Ronald D.

    2016-01-22

    A series of Ti-rich Ni-Ti-Pt ternary alloys with 13 to 18 at. pct Pt were processed by vacuum arc melting and characterized for their transformation behavior to identify shape memory alloys (SMA) that undergo transformation between 448 K and 498 K (175 °C and 225 °C) and achieve recoverable strain exceeding 2 pct. From this broader set of compositions, three alloys containing 15.5 to 16.5 at. pct Pt exhibited transformation temperatures in the vicinity of 473 K (200 °C), thus were targeted for more detailed characterization. Preliminary microstructural evaluation of these three compositions revealed a martensitic microstructure with small amountsmore » of Ti2(Ni,Pt) particles. Room temperature mechanical testing gave a response characteristic of martensitic de-twinning followed by a typical work-hardening behavior to failure. Elevated mechanical testing, performed while the materials were in the austenitic state, revealed yield stresses of approximately 500 MPa and 3.5 pct elongation to failure. Thermal strain recovery characteristics were more carefully investigated with unbiased incremental strain-temperature tests across the 1 to 5 pct strain range, as well as cyclic strain-temperature tests at 3 pct strain. As a result, the unbiased shape recovery results indicated a complicated strain recovery path, dependent on prestrain level, but overall acceptable SMA behavior within the targeted temperature and recoverable strain range.« less

  12. Sintered Cr/Pt and Ni/Au ohmic contacts to B12P2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Frye, Clint D.; Kucheyev, Sergei O.; Edgar, James H.; Voss, Lars F.; Conway, Adam M.; Shao, Qinghui; Nikolic, Rebecca J.

    2015-04-09

    With this study, icosahedral boron phosphide (B12P2) is a wide-bandgap semiconductor possessing interesting properties such as high hardness, chemical inertness, and the reported ability to self-heal from irradiation by high energy electrons. Here, the authors developed Cr/Pt and Ni/Au ohmic contacts to epitaxially grown B12P2 for materials characterization and electronic device development. Cr/Pt contacts became ohmic after annealing at 700 °C for 30 s with a specific contact resistance of 2×10–4 Ω cm2, as measured by the linear transfer length method. Ni/Au contacts were ohmic prior to any annealing, and their minimum specific contact resistance was ~l–4 × 10–4 Ωmore » cm2 after annealing over the temperature range of 500–800 °C. Rutherford backscattering spectrometry revealed a strong reaction and intermixing between Cr/Pt and B12P2 at 700 °C and a reaction layer between Ni and B12P2 thinner than ~25 nm at 500 °C.« less

  13. Interplay between out-of-plane anisotropic L1{sub 1}-type CoPt and in-plane anisotropic NiFe layers in CoPt/NiFe exchange springs

    SciTech Connect (OSTI)

    Saravanan, P.; Hsu, Jen-Hwa Tsai, C. L.; Tsai, C. Y.; Lin, Y. H.; Kuo, C. Y.; Wu, J.-C.; Lee, C.-M.

    2014-06-28

    Films of L1{sub 1}-type CoPt/NiFe exchange springs were grown with different NiFe (Permalloy) layer thickness (t{sub NiFe} = 0–10 nm). X-ray diffraction analysis reveals that the characteristic peak position of NiFe(111) is not affected by the CoPt-layer—confirming the absence of any inter-diffusion between the CoPt and NiFe layers. Magnetic studies indicate that the magnetization orientation of NiFe layer can be tuned through varying t{sub NiFe} and the perpendicular magnetic anisotropy of L1{sub 1}-type CoPt/NiFe films cannot sustain for t{sub NiFe} larger than 3.0 nm due to the existence of exchange interaction at the interface of L1{sub 1}-CoPt and NiFe layers. Magnetic force microscopy analysis on the as-grown samples shows the changes in morphology from maze-like domains with good contrast to hazy domains when t{sub NiFe} ≥ 3.0 nm. The three-dimensional micro-magnetic simulation results demonstrate that the magnetization orientation in NiFe layer is not uniform, which continuously increases from the interface to the top of NiFe layer. Furthermore, the tilt angle of the topmost NiFe layers can be changed over a very wide range from a small number to about 75° by varying t{sub NiFe} from 1 to 10 nm. It is worth noting that there is an abrupt change in the magnetization direction at the interface, for all the t{sub NiFe} investigated. The results of present study demonstrate that the tunable tilted exchange springs can be realized with L1{sub 1}-type CoPt/NiFe bilayers for future applications in three-axis magnetic sensors or advanced spintronic devices demanding inclined magnetic anisotropy.

  14. Final Technical Report: First Principles Investigations for the Ensemble Effects of PdAu and PtAu Bimetallic Nanocatalysts

    SciTech Connect (OSTI)

    Ruqian Wu

    2012-05-18

    Bimetallic surfaces with tunable chemical properties have attracted broad attention in recent years due to their ample potential for heterogeneous catalysis applications. The local chemical properties of constituents are strongly altered from their parent metals by 'ligand effect', a term encompassing the influences of charge transfer, orbital rehybridization and lattice strain. In comparison to the aforementioned, the 'ensemble effect' associated with particular arrangements of the active constituents have received much less attention, despite their notable importance towards the determination of reactivity and selectivity of bimetallic catalysts. We performed theoretical studies for understanding the ensemble effects on bimetallic catalysis: (i) simulations for the formation of different ensembles on PdAu and PtAu nanoclusters; (ii) studies of the size, shape, and substrate dependence of their electronic properties; and (iii) simulations for model reactions such as CO oxidation, methanol, ethylene and water dehydrogenation on PdAu and PtAu nanoclusters. In close collaboration with leading experimental groups, our theoretical research elucidated the fundamentals of Au based bimetallic nanocatalysts.

  15. Thermally enhanced perpendicular magnetic anisotropy behaviors of ultrathin [Co/Pd]{sub n} multilayers via NiO{sub x} capping layer

    SciTech Connect (OSTI)

    Chung, Woo Seong; Lee, Ja Bin; An, Gwang Guk; Yang, Seung Mo; Kim, Jae Hong; Hong, Jin Pyo

    2015-06-01

    We report the enhanced perpendicular magnetic anisotropy (PMA) features of ultrathin [Co/Pd]{sub 3} multilayers (MLs) employing a NiO{sub x} insertion layer at high annealing temperatures. Thermally enhanced PMA in [Co/Pd]{sub 3}/NiO{sub x} (capping layer) MLs were achieved at a specific capping layer thickness, while no PMA responses were observed for a NiO{sub x} (buffer layer)/[Co/Pd]{sub 3} ML, regardless of NiO{sub x} thickness. X-ray diffraction observations, including rocking curves, identified the relatively different crystalline characteristics of the NiO{sub x} capping and buffer layers. Origin of the enhanced PMAs of [Co/Pd]{sub 3} MLs containing a NiO{sub x} capping layer is described based on the NiO{sub x} capping effect possibly providing additional Co/Oxide i-PMA under high-temperature annealing.

  16. Time-domain detection of current controlled magnetization damping in Pt/Ni{sub 81}Fe{sub 19} bilayer and determination of Pt spin Hall angle

    SciTech Connect (OSTI)

    Ganguly, A.; Haldar, A.; Sinha, J.; Barman, A. E-mail: del.atkinson@durham.ac.uk; Rowan-Robinson, R. M.; Jaiswal, S.; Hindmarch, A. T.; Atkinson, D. A. E-mail: del.atkinson@durham.ac.uk

    2014-09-15

    The effect of spin torque from the spin Hall effect in Pt/Ni{sub 81}Fe{sub 19} rectangular bilayer film was investigated using time-resolved magneto-optical Kerr microscopy. Current flow through the stack resulted in a linear variation of effective damping up to ±7%, attributed to spin current injection from the Pt into the Ni{sub 81}Fe{sub 19}. The spin Hall angle of Pt was estimated as 0.11 ± 0.03. The modulation of the damping depended on the angle between the current and the bias magnetic field. These results demonstrate the importance of optical detection of precessional magnetization dynamics for studying spin transfer torque due to spin Hall effect.

  17. Linking morphology with activity through the lifetime of pretreated PtNi nanostructured thin film catalysts

    SciTech Connect (OSTI)

    Cullen, David A.; Lopez-Haro, Miguel; Bayle-Guillemaud, Pascale; Debe, Mark; Steinbach, Andrew J.; Guetaz, L.

    2015-04-10

    In this study, the nanoscale morphology of highly active Pt3Ni7 nanostructured thin film fuel cell catalysts is linked with catalyst surface area and activity following catalyst pretreatments, conditioning and potential cycling. The significant role of fuel cell conditioning on the structure and composition of these extended surface catalysts is demonstrated by high resolution imaging, elemental mapping and tomography. The dissolution of Ni during fuel cell conditioning leads to highly complex, porous structures which were visualized in 3D by electron tomography. Quantification of the rendered surfaces following catalyst pretreatment, conditioning, and cycling shows the important role pore structure plays in surface area, activity, and durability.

  18. Linking morphology with activity through the lifetime of pretreated PtNi nanostructured thin film catalysts

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Cullen, David A.; Lopez-Haro, Miguel; Bayle-Guillemaud, Pascale; Debe, Mark; Steinbach, Andrew J.; Guetaz, L.

    2015-04-10

    In this study, the nanoscale morphology of highly active Pt3Ni7 nanostructured thin film fuel cell catalysts is linked with catalyst surface area and activity following catalyst pretreatments, conditioning and potential cycling. The significant role of fuel cell conditioning on the structure and composition of these extended surface catalysts is demonstrated by high resolution imaging, elemental mapping and tomography. The dissolution of Ni during fuel cell conditioning leads to highly complex, porous structures which were visualized in 3D by electron tomography. Quantification of the rendered surfaces following catalyst pretreatment, conditioning, and cycling shows the important role pore structure plays in surfacemore » area, activity, and durability.« less

  19. High Temperature Oxidation Behavior of gamma-Ni+gamma'-Ni3Al Alloys and Coatings Modified with Pt and Reactive Elements

    SciTech Connect (OSTI)

    Nan Mu

    2007-12-01

    Materials for high-pressure turbine blades must be able to operate in the high-temperature gases (above 1000 C) emerging from the combustion chamber. Accordingly, the development of nickel-based superalloys has been constantly motivated by the need to have improved engine efficiency, reliability and service lifetime under the harsh conditions imposed by the turbine environment. However, the melting point of nickel (1455 C) provides a natural ceiling for the temperature capability of nickel-based superalloys. Thus, surface-engineered turbine components with modified diffusion coatings and overlay coatings are used. Theses coatings are capable of forming a compact and adherent oxide scale, which greatly impedes the further transport of reactants between the high-temperature gases and the underlying metal and thus reducing attack by the atmosphere. Typically, these coatings contain {beta}-NiAl as a principal constituent phase in order to have sufficient aluminum content to form an Al{sub 2}O{sub 3} scale at elevated temperatures. The drawbacks to the currently-used {beta}-based coatings, such as phase instabilities, associated stresses induced by such phase instabilities, and extensive coating/substrate interdiffusion, are major motivations in this study to seek next-generation coatings. The high-temperature oxidation resistance of novel Pt + Hf-modified {gamma}-Ni + {gamma}-Ni{sub 3}Al-based alloys and coatings were investigated in this study. Both early-stage and 4-days isothermal oxidation behavior of single-phase {gamma}-Ni and {gamma}{prime}-Ni{sub 3}Al alloys were assessed by examining the weight changes, oxide-scale structures, and elemental concentration profiles through the scales and subsurface alloy regions. It was found that Pt promotes Al{sub 2}O{sub 3} formation by suppressing the NiO growth on both {gamma}-Ni and {gamma}{prime}Ni{sub 3}Al single-phase alloys. This effect increases with increasing Pt content. Moreover, Pt exhibits this effect even at

  20. Large enhancement of Blocking temperature by control of interfacial structures in Pt/NiFe/IrMn/MgO/Pt multilayers

    SciTech Connect (OSTI)

    Chen, Xi; Wang, Shouguo Han, Gang; Jiang, Shaolong; Yang, Kang; Liu, Qianqian; Yu, Guanghua; Liu, Jialong; Wang, Rongming

    2015-09-15

    The Blocking temperature (T{sub B}) of Pt/NiFe/IrMn/MgO/Pt multilayers was greatly enhanced from far below room temperature (RT) to above RT by inserting 1 nm thick Mg layer at IrMn/MgO interface. Furthermore, the exchange bias field (H{sub eb}) was increased as well by the control of interfacial structures. The evidence for a significant fraction of Mn-O bonding at IrMn/MgO interface without Mg insertion layer was provided by X-ray photoelectron spectroscopy. The bonding between Mn and O can decrease the antiferromagnetism of IrMn film, leading to lower value of T{sub B} in Pt/NiFe/IrMn/MgO/Pt multilayers. Ultrathin Mg film inserted at IrMn/MgO interface acting as an oxygen sinking layer can suppress the oxidation reactions between Mn and O and reduce the formation of Mn-O bonding greatly. The oxidation suppression results in the recovery of the antiferromagnetism of IrMn film, which can enhance T{sub B} and H{sub eb}. Furthermore, the high resolution transmission electron microscopy demonstrates that the Mg insertion layer can efficiently promote a high-quality MgO (200) texture. This study will enhance the understanding of physics in antiferromagnet-based spintronic devices.

  1. Highly Unsaturated Platinum and Palladium Carbenes PtC3 and PdC3 Isolated and Characterized in the Gas Phase

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bittner, Dror M.; Zaleski, Daniel P.; Tew, David P.; Walker, Nicholas R.; Legon, Anthony C.

    2016-02-16

    Carbenes of platinum and palladium, PtC3 and PdC3 , were generated in the gas phase through laser vaporization of a metal target in the presence of a low concentration of a hydrocarbon precursor undergoing supersonic expansion. Rotational spectroscopy and abinitio calculations confirm that both molecules are linear. The geometry of PtC3 was accurately determined by fitting to the experimental moments of inertia of twenty-six isotopologues. In conclusion, the results are consistent with the proposal of an autogenic isolobal relationship between O, Au+ , and Ptatoms.

  2. Diversity of Functionalized Germanium Zintl Clusters: Syntheses and Theoretical Studies of [Ge9PdPPh3]3- and [Ni@(Ge9PdPPh3)]2-

    SciTech Connect (OSTI)

    Sun, Zhong-Ming; Zhao, Ya-Fan; Li, Jun; Wang, Lai S.

    2009-09-10

    A new Zintl cluster [Ge9PdPPh3]3- has been isolated as (2,2,2-crypt)K+ salt through the reaction of K4Ge9 and Pd[PPh3]4 in ethylenediamine solutions and characterized via single-crystal X-ray crystallography. The as-prepared bimetallic [Ge9PdPPh3]3- cluster could successfully trap a nickel atom to form a trimetallic cluster [Ni@(Ge9PdPPh3)]2-. The coordination of Ge94- by PdPPh3 induces a one-electron oxidation and encapsulation of the Ni atom into the Ge93- cage leads to a further one-electron oxidation and a geometry transformation from C4v (nido) to C3v (closo).

  3. Crystal structure and hydrogenation properties of pseudo-binary Mg{sub 6}Pd{sub 0.5}Ni{sub 0.5} complex metallic alloy

    SciTech Connect (OSTI)

    Cuevas, F.; Latroche, M.

    2009-10-15

    The crystal structure of the Ni-substituted Mg{sub 6.10(2)}Pd{sub 0.52(2)}Ni{sub 0.41(2)} complex metallic alloy has been determined by X-ray and neutron powder diffraction. The reaction of this compound at 573 K towards deuterium absorption for pressures up to 23 bar has also been studied. The crystal structure of Mg{sub 6.10(2)}Pd{sub 0.52(2)}Ni{sub 0.41(2)} compound was determined in the light of Samson's [Acta Crystallogr. B 28 (1972) 936) and Makongo's (Philos. Mag. 86 (2006) 427] models for the binary Mg{sub 6}Pd compound. It crystallizes in F4-bar3m space group with lattice parameter 20.13331(7) A. The refined unit-cell composition is Mg{sub 342(1)}Pd{sub 29(1)}Ni{sub 23(1)} with Z=56. Nickel by palladium substitution is not fully random. Nickel atoms preferentially locate on Pd sites with low coordination number due to steric effects. Deuterium uptake is 9.6 D/f.u. under the given conditions of pressure and temperature. Upon absorption, the intermetallic compound disproportionates into MgD{sub 2}, Mg{sub 5}Pd{sub 2} and Mg{sub 2}NiD{sub 4} phases. The Mg{sub 2}NiD{sub 4} phase is observed to crystallize in the orthorhombic LT2 modification for which an averaged crystal structure in the Pcc2 space group is proposed. - Graphical abstract: Coordination polyhedron around site Mg14 in pseudobinary Mg{sub 6}(Pd,Ni) compounds.

  4. Effects of temperature dependent pre-amorphization implantation on NiPt silicide formation and thermal stability on Si(100)

    SciTech Connect (OSTI)

    Ozcan, Ahmet S.; Wall, Donald; Jordan-Sweet, Jean; Lavoie, Christian

    2013-04-29

    Using temperature controlled Si and C ion implantation, we studied the effects of pre-amorphization implantation on NiPt alloy silicide phase formation. In situ synchrotron x-ray diffraction and resistance measurements were used to monitor phase and morphology evolution in silicide films. Results show that substrate amorphization strongly modulate the nucleation of silicide phases, regardless of implant species. However, morphological stability of the thin films is mainly enhanced by C addition, independently of the amorphization depth.

  5. Absolute timing measurements of the Ni-like Pd and Sn soft-x-ray lasers

    SciTech Connect (OSTI)

    Staub, F.; Braud, M.; Balmer, J.E.; Nilsen, J.

    2005-10-15

    The absolute time of emission of the x-ray laser output with respect to the arrival of a 100-ps pump pulse has been measured with the aid of a calibrated timing fiducial. The results show the x-ray laser to appear up to 60 ps (80 ps) before the peak of the pump pulse in the case of the Sn (Pd) x-ray laser, which is in good agreement with simulations obtained from the LASNEX and CRETIN codes. The pulse duration was found to be {approx}45 ps for both the Sn and the Pd x-ray lasers.

  6. Surface profile control of FeNiPt/Pt core/shell nanowires for oxygen reduction reaction

    SciTech Connect (OSTI)

    Zhu, Huiyuan; Zhang, Sen; Su, Dong; Jiang, Guangming; Sun, Shouheng

    2015-03-18

    The ever-increasing energy demand requires renewable energy schemes with low environmental impacts. Electrochemical energy conversion devices, such as fuel cells, combine fuel oxidization and oxygen reduction reactions and have been studied extensively for renewable energy applications. However, their energy conversion efficiency is often limited by kinetically sluggish chemical conversion reactions, especially oxygen reduction reaction (ORR). [1-5] To date, extensive efforts have been put into developing efficient ORR catalysts with controls on catalyst sizes, compositions, shapes and structures. [6-12] Recently, Pt-based catalysts with core/shell and one-dimensional nanowire (NW) morphologies were found to be promising to further enhance ORR catalysis. With the core/shell structure, the ORR catalysis of a nanoparticle (NP) catalyst can be tuned by both electronic and geometric effects at the core/shell interface. [10,13,14] With the NW structure, the catalyst interaction with the conductive support can be enhanced to facilitate electron transfer between the support and the NW catalyst and to promote ORR. [11,15,16]

  7. Surface profile control of FeNiPt/Pt core/shell nanowires for oxygen reduction reaction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhu, Huiyuan; Zhang, Sen; Su, Dong; Jiang, Guangming; Sun, Shouheng

    2015-03-18

    The ever-increasing energy demand requires renewable energy schemes with low environmental impacts. Electrochemical energy conversion devices, such as fuel cells, combine fuel oxidization and oxygen reduction reactions and have been studied extensively for renewable energy applications. However, their energy conversion efficiency is often limited by kinetically sluggish chemical conversion reactions, especially oxygen reduction reaction (ORR). [1-5] To date, extensive efforts have been put into developing efficient ORR catalysts with controls on catalyst sizes, compositions, shapes and structures. [6-12] Recently, Pt-based catalysts with core/shell and one-dimensional nanowire (NW) morphologies were found to be promising to further enhance ORR catalysis. With themore » core/shell structure, the ORR catalysis of a nanoparticle (NP) catalyst can be tuned by both electronic and geometric effects at the core/shell interface. [10,13,14] With the NW structure, the catalyst interaction with the conductive support can be enhanced to facilitate electron transfer between the support and the NW catalyst and to promote ORR. [11,15,16]« less

  8. Paramagnetism, superparamagnetism, and spin-glass behavior in bulk amorphous Pd{endash}Ni{endash}Fe{endash}P alloys

    SciTech Connect (OSTI)

    Shen, T.D.; Schwarz, R.B.; Thompson, J.D. [Materials Science and Technology Division, Mail Stop G755, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Materials Science and Technology Division, Mail Stop G755, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1999-04-01

    We have investigated the magnetic properties of bulk amorphous Pd{sub 40}Ni{sub 40{minus}x}Fe{sub x}P{sub 20} (x=0{endash}17.5) alloys. For Pd{sub 40}Ni{sub 40}P{sub 20} (x=0), the magnetic susceptibility consists of temperature-independent and Curie{endash}Weiss-type terms. Alloys with x{ge}5 are paramagnetic at high temperatures. With decreasing temperature, the amorphous alloys become superparamagnetic. At even lower temperatures, and under a weak applied magnetic field, these alloys are spin glasses, as evidenced by static and dynamic magnetic measurements. The spin-freezing temperature increases with increasing iron content and this is attributed to the role of the Ruderman{endash}Kittel{endash}Kasuya{endash}Yosida interaction in creating the spin-glass state. The occurrence of a reentrant spin-glass behavior on cooling (superparamagnetism-to-ferromagnetism-to-spin-glass transition) is also observed for x=17.5 at a field {ge}50 Oe. An unexpected result is that the ferromagnetic state in the present bulk metallic glasses is {ital field induced}. Evidence for the field-induced ferromagnetic-like order is obtained from (a) straight regions in the susceptibility versus temperature curves measured at various fields, (b) an Arrott plot, and (c) time-independent magnetization. With increasing applied field, the spin-freezing temperature decreases and the Curie temperature increases, broadening the temperature range of the field-induced ferromagnetic-like state. The temporal decay of the thermoremanent magnetization in the amorphous alloy with x=17.5 is slower than that in typical crystalline spin glasses. The spin-freezing temperature of the amorphous alloy with x=17.5 decreases approximately logarithmically with applied field, which differs from the prediction of N{acute e}el{close_quote}s model for spin glasses. {copyright} {ital 1999 American Institute of Physics.}

  9. Large exchange bias enhancement in (Pt(or Pd)/Co)/IrMn/Co trilayers with ultrathin IrMn thanks to interfacial Cu dusting

    SciTech Connect (OSTI)

    Vinai, G. [SPINTEC, UMR 8191 CEA/CNRS/UJF/Grenoble-INP, CEA/INAC, 17, rue des Martyrs, 38054 Grenoble (France); Crocus Technology, 4 Place Robert Schuman, 38054 Grenoble (France); Moritz, J. [Institut Jean Lamour, UMR 7198 CNRS - Universit de Lorraine, Bd des Aiguillettes, BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex (France); Bandiera, S. [Crocus Technology, 4 Place Robert Schuman, 38054 Grenoble (France); Prejbeanu, I. L.; Dieny, B. [SPINTEC, UMR 8191 CEA/CNRS/UJF/Grenoble-INP, CEA/INAC, 17, rue des Martyrs, 38054 Grenoble (France)

    2014-04-21

    The magnitude of exchange bias (H{sub ex}) at room temperature can be significantly enhanced in IrMn/Co and (Pt(or Pd)/Co)/IrMn/Co structures thanks to the insertion of an ultrathin Cu dusting layer at the IrMn/Co interface. The combination of trilayer structure and interfacial Cu dusting leads to a three-fold increase in H{sub ex} as compared to the conventional IrMn/Co bilayer structure, with an increased blocking temperature (T{sub B}) and a concave curvature of the temperature dependence H{sub ex}(T), ideal for improved Thermally Assisted-Magnetic Random Access Memory storage layer. This exchange bias enhancement is ascribed to a reduction of the spin frustration at the IrMn/Co interface thanks to interfacial Cu addition.

  10. Pt monolayer shell on nitrided alloy core — A path to highly stable oxygen reduction catalyst

    SciTech Connect (OSTI)

    Hu, Jue; Kuttiyiel, Kurian A.; Sasaki, Kotaro; Su, Dong; Yang, Tae -Hyun; Park, Gu -Gon; Zhang, Chengxu; Chen, Guangyu; Adzic, Radoslav R.

    2015-07-22

    The inadequate activity and stability of Pt as a cathode catalyst under the severe operation conditions are the critical problems facing the application of the proton exchange membrane fuel cell (PEMFC). Here we report on a novel route to synthesize highly active and stable oxygen reduction catalysts by depositing Pt monolayer on a nitrided alloy core. The prepared PtMLPdNiN/C catalyst retains 89% of the initial electrochemical surface area after 50,000 cycles between potentials 0.6 and 1.0 V. By correlating electron energy-loss spectroscopy and X-ray absorption spectroscopy analyses with electrochemical measurements, we found that the significant improvement of stability of the PtMLPdNiN/C catalyst is caused by nitrogen doping while reducing the total precious metal loading.

  11. Suppression of the spin pumping in Pd/Ni{sub 81}Fe{sub 19} bilayers with nano-oxide layer

    SciTech Connect (OSTI)

    Kim, Duck-Ho; Kim, Hong-Hyoun; You, Chun-Yeol

    2011-08-15

    We demonstrate that the spin pumping effect can be effectively suppressed with a nano-oxide layer. Spin pumping effect manifests itself by an enhancement of the Gilbert damping parameter in normal metal/ferromagnetic hetero-structures, while many spintronics devices prefer smaller damping parameter. Since the spin pumping effect is directly related with the spin dependent interface conductance, we can modify the spin pumping by altering the interface conductance with the nano-oxide layer. We prepared series of Pd/Ni{sub 81}Fe{sub 19} bilayers with different pausing time between Pd and Ni{sub 81}Fe{sub 19} depositions in order to control the interface conductance. The Gilbert damping parameters are determined from the line-width measurements in the ferromagnetic resonance spectra for each pausing time sample. They are 0.0490, 0.0296, 0.0278, and 0.0251 for 0, 6, 30, and 60 s pausing time, respectively. We find that the damping parameter of Pd/Ni{sub 81}Fe{sub 19} is almost recovered to one of the Cu/Ni{sub 81}Fe{sub 19} bilayer with 60 s pausing time, while the static magnetic properties are not noticeably changed.

  12. Microstructure and transformation behavior of Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} high temperature shape-memory alloy with Sc micro-addition

    SciTech Connect (OSTI)

    Ramaiah, K.V.; Saikrishna, C.N.; Gouthama; Bhaumik, S.K.

    2015-08-15

    NiTiPd shape-memory alloys (SMAs) are potential functional materials for use as solid-state actuators in the temperature range 100–250 °C. The present study investigates the effect of 1.0 at.% Sc micro-addition to Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} alloy, Sc replacing either Ti or Ni. Results show that all the three alloys studied have stable transformation behavior on stress-free thermal cycling and hence, are suitable for cyclic actuation applications. However, the addition of Sc to NiTiPd alloy leads to decrease of transformation temperatures, the magnitude of decrease being greater for the alloy with Sc replacing Ni. The martensite finish (M{sub f}) temperature of 181 °C for the NiTiPd alloy decreased to 139 °C for Sc replacing Ti and 83 °C for Sc replacing Ni. Also, the indentation modulus of NiTiPdSc (Sc replacing Ni) alloy is found to be significantly low compared to the other alloys. Analysis indicates that the observed differences in the alloy properties are related to the solubility of Sc in the NiTiPd matrix. While the quaternary NiTiPdSc alloy, Sc replacing Ti, has a single phase microstructure, the alloy with Sc replacing Ni shows the presence of Sc-rich and TiPd-type second phases in the microstructure. TEM examination revealed that the TiPd-type phase has a distinct rod-like morphology (30–50 nm) arranged in a grid-like structure. The transformation and indentation behavior of the alloys is elucidated using thermodynamic calculations of frictional energy and an electronic structure based analysis. - Highlights: • TEM of Ni{sub 23.7}Ti{sub 50.3}Pd{sub 25}Sc{sub 1} showed distinct grid of TiPd-type phase nanorods < 50 nm. • Stress-free thermal cycling of all the three alloys showed stable transformation behavior. • Ni{sub 24.7}Ti{sub 49.3}Pd{sub 25}Sc{sub 1} and Ni{sub 23.7}Ti{sub 50.3}Pd{sub 25}Sc{sub 1} showed single and multiphase structures. • Sc micro-addition (1 at.%) to Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} alloy decreased TTs

  13. The effect of Au and Ni doping on the heavy fermion state of the Kondo lattice antiferromagnet CePtZn

    SciTech Connect (OSTI)

    Dhar, S. K.; Aoki, Y.; Suemitsu, B.; Miyazaki, R.; Provino, A.; Manfrinetti, P.

    2014-05-07

    We have probed the effect of doping CePtZn with Au and Ni and also investigated in detail the magnetic behavior of the iso-structural CeAuZn. A magnetic ground state is observed in both CePt{sub 0.9}Au{sub 0.1}Zn and CePt{sub 0.9}Ni{sub 0.1}Zn with T{sub N}?=?2.1 and 1.1?K and the coefficient of the linear term of electronic heat capacity ??=?0.34 and 0.9?J/mol K{sup 2}, respectively. The corresponding values for CePtZn are 1.7?K and 0.6?J/mol K{sup 2}. The altered values of T{sub N} and ? show that the electronic correlations in CePtZn are affected by doping with Au and Ni. CeAuZn orders magnetically near 1.7?K and its electrical resistivity shows a normal metallic behavior. Together with a ? of 0.022?J/mol K{sup 2} the data indicate a weak 4f-conduction electron hybridization in CeAuZn characteristic of normal trivalent cerium based systems.

  14. Systematics of the temperature-dependent interplane resistivity in Ba(Fe1-xMx)₂As₂ (M=Co, Rh, Ni, and Pd)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tanatar, M. A.; Ni, N.; Thaler, A.; Bud’ko, S. L.; Canfield, P. C.; Prozorov, R.

    2011-07-27

    Temperature-dependent interplane resistivity ρc(T) was measured systematically as a function of transition-metal substitution in the iron-arsenide superconductors Ba(Fe1-xMx)₂As₂, M=Ni, Pd, Rh. The data are compared with the behavior found in Ba(Fe1-xCox)₂As₂, revealing resistive signatures of pseudogap. In all compounds we find resistivity crossover at a characteristic pseudogap temperature T* from nonmetallic to metallic temperature dependence on cooling. Suppression of T* proceeds very similarly in cases of Ni and Pd doping and much faster than in similar cases of Co and Rh doping. In cases of Co and Rh doping an additional minimum in the temperature-dependent ρc emerges for high dopings,more » when superconductivity is completely suppressed. These features are consistent with the existence of a charge gap covering part of the Fermi surface. The part of the Fermi surface affected by this gap is notably larger for Ni- and Pd-doped compositions than in Co- and Rh-doped compounds.« less

  15. Weak hybridization and isolated localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    White, B. D.; Yazici, D.; Ho, P. -C.; Kanchanavatee, N.; Pouse, N.; Fang, Y.; Breindel, A. J.; Friedman, A. J.; Maple, M. B.

    2015-07-20

    Here, we report the physical properties of single crystals of the compounds CeT2Cd20 (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of ~6.7- 6.8 Å between Ce ions favor the localized magnetic moments that are observed in measurements of the magnetization. The strength of the Ruderman-Kittel-Kasuya- Yosida magnetic exchange interaction between the localized moments is severely limited by the large Ce-Ce separations and by weak hybridization between localized Ce 4f and itinerant electron states. Measurements of electrical resistivity performed down to 0.138 K were unable to observe evidence for the emergence of magnetic order;more » however, magnetically-ordered ground states with very low transition temperatures are still expected in these compounds despite the isolated nature of the localized magnetic moments. Such a fragile magnetic order could be highly susceptible to tuning via applied pressure, but evidence for the emergence of magnetic order has not been observed so far in our measurements up to 2.5 GPa.« less

  16. The Effects of Oxide Supports on the Low Temperature Hydrogenation Activity of Acetone over Pt/Ni Bimetallic Catalysts on SiO2 gamma-Al2O3 and TiO2

    SciTech Connect (OSTI)

    S Qi; B Cheney; R Zheng; W Lonergan; W Yu; J Chen

    2011-12-31

    Low temperature (308 K) hydrogenation of acetone was used as a probe reaction to investigate the support effect on the hydrogenation activity of Pt/Ni bimetallic catalysts supported on TiO{sub 2}, SiO{sub 2} and {gamma}-Al{sub 2}O{sub 3}. The oxide supports significantly affected the catalytic properties of Pt/Ni catalysts, in which Pt/Ni/SiO2 bimetallic catalysts exhibited significantly higher activity than the other two bimetallic catalysts. TEM measurements revealed that the three supported Pt/Ni bimetallic catalysts have similar particle size distribution, while CO chemisorption measurements showed very different chemisorption capacity. Extended X-Ray absorption fine structure (EXAFS) measurements of the Pt L{sub III}-edge indicated that Pt atoms were fully reduced and the Pt-Ni bimetallic bonds were formed on all three catalysts. The extent of Pt-Ni bond formation followed the trend of SiO{sub 2} > {gamma}-Al{sub 2}O{sub 3} > TiO{sub 2}, which correlated very well with the hydrogenation activity.

  17. Sintered Cr/Pt and Ni/Au ohmic contacts to B12P2

    SciTech Connect (OSTI)

    Frye, Clint D.; Kucheyev, Sergei O.; Edgar, James H.; Voss, Lars F.; Conway, Adam M.; Shao, Qinghui; Nikolic, Rebecca J.

    2015-04-09

    With this study, icosahedral boron phosphide (B12P2) is a wide-bandgap semiconductor possessing interesting properties such as high hardness, chemical inertness, and the reported ability to self-heal from irradiation by high energy electrons. Here, the authors developed Cr/Pt and Ni/Au ohmic contacts to epitaxially grown B12P2 for materials characterization and electronic device development. Cr/Pt contacts became ohmic after annealing at 700 °C for 30 s with a specific contact resistance of 2×10–4 Ω cm2, as measured by the linear transfer length method. Ni/Au contacts were ohmic prior to any annealing, and their minimum specific contact resistance was ~l–4 × 10–4 Ω cm2 after annealing over the temperature range of 500–800 °C. Rutherford backscattering spectrometry revealed a strong reaction and intermixing between Cr/Pt and B12P2 at 700 °C and a reaction layer between Ni and B12P2 thinner than ~25 nm at 500 °C.

  18. First-principles studies of structural stabilities and enthalpies of formation of refractory intermetallics: TM and TM3 (T = Ti, Zr, Hf; M = Ru, Rh, Pd, Os, Ir, Pt)

    SciTech Connect (OSTI)

    Xing, Weiwei; Chen, X.; Li, Dianzhong; Li, Y. Y.; Fu, Chong Long; Meschel, S.

    2012-01-01

    Using first-principles local density functional approach, we have calculated the ground-state structural phase stabilities and enthalpies of formation of thirty-six binary transition-metal refractory TM and TM3 compounds formed by Group IV elements T (T = Ti, Zr, Hf) and platinum group elements M (M = Ru, Rh, Pd, Os, Ir, Pt) . We compared our results with the available experimental data and found good agreement between theory and experiment in both the trends of structural stabilities and the magnitudes of formation enthalpies. Moreover, based on our calculated results, an empirical relationship between cohesive energies ( E) and melting temperatures (Tm) was derived as Tm = 0.0292 E/kB (where kB is the Boltzmann constant) for both TM and TM3 compounds.

  19. Magnetic anisotropy of Fe{sub 1−y}X{sub y}Pt-L1{sub 0} [X = Cr, Mn, Co, Ni, Cu] bulk alloys

    SciTech Connect (OSTI)

    Cuadrado, R.; Chantrell, R. W.; Klemmer, Timothy J.

    2014-10-13

    We demonstrate by means of fully relativistic first principles calculations that, by substitution of Fe by Cr, Mn, Co, Ni, or Cu in FePt-L1{sub 0} bulk alloys, with fixed Pt content, it is possible to tune the magnetocrystalline anisotropy energy by adjusting the content of the non-magnetic species in the material. The changes in the geometry due to the inclusion of each element induces different values of the tetragonality and hence changes in the magnetic anisotropy and in the net magnetic moment. The site resolved magnetic moments of Fe increase with the X content while those of Pt and X are simultaneously reduced. The calculations are in good quantitative agreement with experimental data and demonstrate that models with fixed band structure but varying numbers of electrons per unit cell are insufficient to describe the experimental data for doped FePt-L1{sub 0} alloys.

  20. Weak hybridization and isolated localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd)

    SciTech Connect (OSTI)

    White, B. D.; Yazici, D.; Ho, P. -C.; Kanchanavatee, N.; Pouse, N.; Fang, Y.; Breindel, A. J.; Friedman, A. J.; Maple, M. B.

    2015-07-20

    Here, we report the physical properties of single crystals of the compounds CeT2Cd20 (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of ~6.7- 6.8 Å between Ce ions favor the localized magnetic moments that are observed in measurements of the magnetization. The strength of the Ruderman-Kittel-Kasuya- Yosida magnetic exchange interaction between the localized moments is severely limited by the large Ce-Ce separations and by weak hybridization between localized Ce 4f and itinerant electron states. Measurements of electrical resistivity performed down to 0.138 K were unable to observe evidence for the emergence of magnetic order; however, magnetically-ordered ground states with very low transition temperatures are still expected in these compounds despite the isolated nature of the localized magnetic moments. Such a fragile magnetic order could be highly susceptible to tuning via applied pressure, but evidence for the emergence of magnetic order has not been observed so far in our measurements up to 2.5 GPa.

  1. Quantum Critical Behavior in the Heavy Fermion Single Crystal Ce(Ni0.935Pd0.065)2Ge2

    SciTech Connect (OSTI)

    Wang, Cuihuan [ORNL; Lawrence, J M [University of California, Irvine; Christianson, Andrew D [ORNL; Chang, S [NIST Center for Neutron Research (NCRN), Gaithersburg, MD; Bauer, E D [Los Alamos National Laboratory (LANL); Gofryk, K [Los Alamos National Laboratory (LANL); Ronning, F [Los Alamos National Laboratory (LANL); Thompson, J D [Los Alamos National Laboratory (LANL); McClellan, K J [Los Alamos National Laboratory (LANL); Rodriguez-Rivera, J A [NCNR and University of Maryland; Lynn, J W [NIST Center for Neutron Research (NCRN), Gaithersburg, MD

    2011-01-01

    We have performed magnetic susceptibility, specific heat, resistivity, and inelastic neutron scattering measurements on a single crystal of the heavy Fermion compound Ce(Ni{sub 0.935}Pd{sup 0.065}){sub 2}Ge{sub 2}, which is believed to be close to a quantum critical point (QCP) at T = 0. At lowest temperature (1.8--3.5 K), the magnetic susceptibility behaves as {chi}(T)-{chi} (0) {proportional_to} T{sup -1/6} with {chi} (0) = 0.032 x 10{sup -6} m{sup 3}/mole (0.0025 emu/mole). For T < 1 K, the specific heat can be fit to the formula {Delta} C/T = {gamma}{sub 0} - T{sup 1/2} with {gamma}{sub 0} of order 700 mJ/mole-K{sup 2}. The resistivity behaves as {rho} = {rho}{sub 0} + AT{sup 3/2} for temperatures below 2 K. This low temperature behavior for {gamma} (T) and {rho} (T) is in accord with the SCR theory of Moriya and Takimoto. The inelastic neutron scattering spectra show a broad peak near 1.5 meV that appears to be independent of Q; we interpret this as Kondo scattering with T{sub K} = 17 K. In addition, the scattering is enhanced near Q=(1/2, 1/2, 0) with maximum scattering at {Delta} E = 0.45 meV{sup -}; we interpret this as scattering from antiferromagnetic fluctuations near the antiferromagnetic QCP.

  2. Durable pd-based alloy and hydrogen generation membrane thereof

    DOE Patents [OSTI]

    Benn, Raymond C.; Opalka, Susanne M.; Vanderspurt, Thomas Henry

    2010-02-02

    A durable Pd-based alloy is used for a H.sub.2-selective membrane in a hydrogen generator, as in the fuel processor of a fuel cell plant. The Pd-based alloy includes Cu as a binary element, and further includes "X", where "X" comprises at least one metal from group "M" that is BCC and acts to stabilize the .beta. BCC phase for stability during operating temperatures. The metal from group "M" is selected from the group consisting of Fe, Cr, Nb, Ta, V, Mo, and W, with Nb and Ta being most preferred. "X" may further comprise at least one metal from a group "N" that is non-BCC, preferably FCC, that enhances other properties of the membrane, such as ductility. The metal from group "N" is selected from the group consisting of Ag, Au, Re, Ru, Rh, Y, Ce, Ni, Ir, Pt, Co, La and In. The at. % of Pd in the binary Pd--Cu alloy ranges from about 35 at. % to about 55 at. %, and the at. % of "X" in the higher order alloy, based on said binary alloy, is in the range of about 1 at. % to about 15 at. %. The metals are selected according to a novel process.

  3. Effect of the spin-twist structure on the spin-wave dynamics in Fe{sub 55}Pt{sub 45}/Ni{sub 80}Fe{sub 20} exchange coupled bi-layers with varying Ni{sub 80}Fe{sub 20} thickness

    SciTech Connect (OSTI)

    Pal, Semanti; Barman, Saswati Barman, Anjan; Hellwig, Olav

    2014-05-07

    We have investigated optically induced ultrafast magnetization dynamics of a series of Fe{sub 55}Pt{sub 45}/Ni{sub 80}Fe{sub 20} exchange spring bi-layers with varying Ni{sub 80}Fe{sub 20} thickness. Rich spin-wave spectra are observed; whose frequency shows a strong dependence on the Ni{sub 80}Fe{sub 20} layer thickness. Micromagnetic simulations based on a simplified magnetic microstructure were able to reproduce the experimental data qualitatively. The spin twist structure introduced in the Ni{sub 80}Fe{sub 20} layer gives rise to new modes in the composite system as opposed to the bare Ni{sub 80}Fe{sub 20} films.

  4. An analysis of the pull strength behaviors of fine-pitch, flip chip solder interconnections using a Au-Pt-Pd thick film conductor on Low-Temperature, Co-fired Ceramic (LTCC) substrates.

    SciTech Connect (OSTI)

    Uribe, Fernando R.; Kilgo, Alice C.; Grazier, John Mark; Vianco, Paul Thomas; Zender, Gary L.; Hlava, Paul Frank; Rejent, Jerome Andrew

    2008-09-01

    The assembly of the BDYE detector requires the attachment of sixteen silicon (Si) processor dice (eight on the top side; eight on the bottom side) onto a low-temperature, co-fired ceramic (LTCC) substrate using 63Sn-37Pb (wt.%, Sn-Pb) in a double-reflow soldering process (nitrogen). There are 132 solder joints per die. The bond pads were gold-platinum-palladium (71Au-26Pt-3Pd, wt.%) thick film layers fired onto the LTCC in a post-process sequence. The pull strength and failure modes provided the quality metrics for the Sn-Pb solder joints. Pull strengths were measured in both the as-fabricated condition and after exposure to thermal cycling (-55/125 C; 15 min hold times; 20 cycles). Extremely low pull strengths--referred to as the low pull strength phenomenon--were observed intermittently throughout the product build, resulting in added program costs, schedule delays, and a long-term reliability concern for the detector. There was no statistically significant correlation between the low pull strength phenomenon and (1) the LTCC 'sub-floor' lot; (2) grit blasting the LTCC surfaces prior to the post-process steps; (3) the post-process parameters; (4) the conductor pad height (thickness); (5) the dice soldering assembly sequence; or (5) the dice pull test sequence. Formation of an intermetallic compound (IMC)/LTCC interface caused by thick film consumption during either the soldering process or by solid-state IMC formation was not directly responsible for the low-strength phenomenon. Metallographic cross sections of solder joints from dice that exhibited the low pull strength behavior, revealed the presence of a reaction layer resulting from an interaction between Sn from the molten Sn-Pb and the glassy phase at the TKN/LTCC interface. The thick film porosity did not contribute, explicitly, to the occurrence of reaction layer. Rather, the process of printing the very thin conductor pads was too sensitive to minor thixotropic changes to ink, which resulted in

  5. Pull strength evaluation of Sn-Pb solder joints made to Au-Pt-Pd and Au thick film structures on low-temperature co-fired ceramic -final report for the MC4652 crypto-coded switch (W80).

    SciTech Connect (OSTI)

    Uribe, Fernando; Vianco, Paul Thomas; Zender, Gary L.

    2006-06-01

    A study was performed that examined the microstructure and mechanical properties of 63Sn-37Pb (wt.%, Sn-Pb) solder joints made to thick film layers on low-temperature co-fired (LTCC) substrates. The thick film layers were combinations of the Dupont{trademark} 4596 (Au-Pt-Pd) conductor and Dupont{trademark} 5742 (Au) conductor, the latter having been deposited between the 4596 layer and LTCC substrate. Single (1x) and triple (3x) thicknesses of the 4596 layer were evaluated. Three footprint sizes were evaluated of the 5742 thick film. The solder joints exhibited excellent solderability of both the copper (Cu) lead and thick film surface. In all test sample configurations, the 5742 thick film prevented side wall cracking of the vias. The pull strengths were in the range of 3.4-4.0 lbs, which were only slightly lower than historical values for alumina (Al{sub 2}O{sub 3}) substrates. General (qualitative) observations: (a) The pull strength was maximized when the total number of thick film layers was between two and three. Fewer that two layers did not develop as strong of a bond at the thick film/LTCC interface; more than three layers and of increased footprint area, developed higher residual stresses at the thick film/LTCC interface and in the underlying LTCC material that weakened the joint. (b) Minimizing the area of the weaker 4596/LTCC interface (e.g., larger 5742 area) improved pull strength. Specific observations: (a) In the presence of vias and the need for the 3x 4596 thick film, the preferred 4596:5742 ratio was 1.0:0.5. (b) For those LTCC components that require the 3x 4596 layer, but do not have vias, it is preferred to refrain from using the 5742 layer. (c) In the absence of vias, the highest strength was realized with a 1x thick 5742 layer, a 1x thick 4596 layer, and a footprint ratio of 1.0:1.0.

  6. Transport properties of Ce{sub 2}Ni{sub 2}Sn and Ce{sub 2}Pd{sub 2.05}Sn{sub 0.95} Kondo lattice systems

    SciTech Connect (OSTI)

    Pinto, R.P.; Amado, M.M.; Braga, M.E.; de Azevedo, M.M.; Sousa, J.B.; Chevalier, B.; Etourneau, J.

    1997-04-01

    We report experimental data on thermoelectric power S, electrical resistivity {rho}, and the magnetoresistivity of the antiferromagnet Kondo stannides Ce{sub 2}Ni{sub 2}Sn (T{sub N}=4.7 K) and Ce{sub 2}Pd{sub 2.05}Sn{sub 0.95} (T{sub N}=4.7 K). The essential features of the S(T) curves resemble those of heavy fermion systems such as CeCu{sub 2}Si{sub 2}: a broad and positive maximum at intermediate temperatures, followed by a sharper negative minimum at lower temperatures. S values are is considerably smaller in Ce{sub 2}Pd{sub 2.05}Sn{sub 0.95} than in Ce{sub 2}Ni{sub 2}Sn. The positive peak originates from the incoherent Kondo scattering by the excited crystal field levels of the Ce ion ground state. The negative peak might be related to the shape of the density of states associated with the Abrikosov{endash}Suhl resonance. The change of sign in S(T) between its minimum and maximum at T{sup {asterisk}} can be assigned to the fact that the Fermi level sinks below the upper band at T{gt}T{sup {asterisk}}. This behavior and the maximum observed in the {rho}(T) curve at this temperature can be discussed in terms of the electron polaron model, although one must also take into account the crystal field effect. The role played by the crystal field effect, which is more important in Ce{sub 2}Pd{sub 2.05}Sn{sub 0.95}, is analyzed for this compound, providing the magnitude of the crystal field splitting. Magnetoresistivity was also measured in both compounds. The results are consistent with the important role of the Kondo effect at low temperatures and suggest the splitting of the double degenerate bands at T{gt}T{sup {asterisk}}. {copyright} {ital 1997 American Institute of Physics.}

  7. Quantum critical fluctuations in the heavy fermion compound Ce(Ni0.935 Pd0.065)2Ge2

    SciTech Connect (OSTI)

    Wang, C. H.; Poudel, L.; Taylor, A. E.; Lawrence, J. M.; Christianson, A. D.; Chang, S.; Rodriguez-Rivera, J. A.; Lynn, J. W.; Podlesnyak, A. A.; Ehlers, G.; Baumbach, R. E.; Bauer, E. D.; Gofryk, K.; Ronning, F.; McClellan, K. J.; Thompson, J. D.

    2015-01-14

    Electric resistivity, specific heat, magnetic susceptibility, and inelastic neutron scattering experi- ments were performed on a single crystal of the heavy fermion compound Ce(Ni0.935 Pd0.065)2Ge2 in order to study the spin fluctuations near an antiferromagnetic (AF) quantum critical point (QCP). The resistivity and the specific heat coefficient for T ≤ 1 K exhibit the power law behavior expected for a 3D itinerant AF QCP (ρ(T) ~ T3/2 and γ(T) ~ γ0 - bT1/2). However, for 2 ≤ T ≤ 10 K, the susceptibility and specific heat vary as log T and the resistivity varies linearly with temperature. Furthermore, despite the fact that the resistivity and specific heat exhibit the non-Fermi liquid behavior expected at a QCP, the correlation length, correlation time, and staggered susceptibility of the spin fluctuations remain finite at low temperature. We suggest that these deviations from the divergent behavior expected for a QCP may result from alloy disorder.

  8. Effect of Spin-Crossover-Induced Pore Contraction on CO2–Host Interactions in the Porous Coordination Polymers [Fe(pyrazine)M(CN)4] (M = Ni, Pt)

    SciTech Connect (OSTI)

    Culp, Jeffrey T; Chen, De-Li; Liu, Jinchen; Chirdon, Danielle; Kauffman, Kristi; Goodman, Angela; Johnson, J Karl

    2013-02-01

    Variable-temperature in situ ATR-FTIR spectra are presented for the porous spin-crossover compounds [Fe(pyrazine)Ni(CN)4] and [Fe(pyrazine)Pt(CN)4] under CO2 pressures of up to 8 bar. Significant shifts in the ν3 and ν2 IR absorption bands of adsorbed CO2 are observed as the host materials undergo transition between low- and high-spin states. Computational models used to determine the packing arrangement of CO2 within the pore structures show a preferred orientation of one of the adsorbed CO2 molecules with close O=C=O···H contacts with the pyrazine pillar ligands. The interaction is a consequence of the commensurate distance of the inter-pyrazine separations and the length of the CO2 molecule, which allows the adsorbed CO2 to effectively bridge the pyrazine pillars in the structure. The models were used to assign the distinct shifts in the IR absorption bands of the adsorbed CO2 that arise from changes in the O=C=O···H contacts that strengthen and weaken in correlation with changes in the Fe–N bond lengths as the spin state of Fe changes. The results indicate that spin-crossover compounds can function as a unique type of flexible sorbent in which the pore contractions associated with spin transition can affect the strength of CO2–host interactions.

  9. Synthesis and Characterization of Platinum Monolayer Oxygen-Reduction Electrocatalysts with Co-Pd Core-Shell Nanoparticle Support

    SciTech Connect (OSTI)

    Shao,M.; Sasaki, K.; Marinkovic, N.; Zhang, L.; Adzic, R.

    2007-01-01

    We synthesized Pt monolayer electrocatalysts for oxygen-reduction using a new method to obtain the supporting core-shell nanoparticles. They consist of a Pt monolayer deposited on carbon-supported Co-Pd core-shell nanoparticles with the diameter of 3-4 nm. The nanoparticles were made using a redox-transmetalation (electroless deposition) method involving the oxidation of Co by Pd cations, yielding a Pd shell around the Co core. The quality of the thus-formed core-shell structure was verified using transmission electron microscopy and X-ray absorption spectroscopy, while cyclic voltammetry was employed to confirm the lack of Co oxidation (dissolution). A Pt monolayer was deposited on the Co-Pd core-shell nanoparticles by the galvanic displacement of a Cu monolayer obtained by underpotential deposition. The total noble metal mass-specific activity of this Pt monolayer electrocatalyst was ca. 3-fold higher than that of commercial Pt/C electrocatalysts.

  10. Fuel cell with Pt/Pd electrocatalyst electrode

    DOE Patents [OSTI]

    Stonehart, Paul

    1983-01-01

    An electrode for use in a phosphoric acid fuel cell comprising a graphitized or partially graphitized carbon support having a platinum/palladium electrocatalyst thereon. Preferably, the platinum/palladium catalyst comprises 20 to 65 weight percent palladium.

  11. PT-symmetric strings

    SciTech Connect (OSTI)

    Amore, Paolo; Fernndez, Francisco M.; Garcia, Javier; Gutierrez, German

    2014-04-15

    We study both analytically and numerically the spectrum of inhomogeneous strings with PT-symmetric density. We discuss an exactly solvable model of PT-symmetric string which is isospectral to the uniform string; for more general strings, we calculate exactly the sum rules Z(p)??{sub n=1}{sup ?}1/E{sub n}{sup p}, with p=1,2, and find explicit expressions which can be used to obtain bounds on the lowest eigenvalue. A detailed numerical calculation is carried out for two non-solvable models depending on a parameter, obtaining precise estimates of the critical values where pair of real eigenvalues become complex. -- Highlights: PT-symmetric Hamiltonians exhibit real eigenvalues when PT symmetry is unbroken. We study PT-symmetric strings with complex density. They exhibit regions of unbroken PT symmetry. We calculate the critical parameters at the boundaries of those regions. There are exact real sum rules for some particular complex densities.

  12. Synthesis and characterization of Pd(0), PdS, and Pd-PdO core-shell nanoparticles by solventless thermolysis of a Pd-thiolate cluster

    SciTech Connect (OSTI)

    Jose, Deepa; Jagirdar, Balaji R.

    2010-09-15

    Colloids of palladium nanoparticles have been prepared by the solvated metal atom dispersion (SMAD) method. The as-prepared Pd colloid consists of particles with an average diameter of 2.8{+-}0.1 nm. Digestive ripening of the as-prepared Pd colloid, a process involving refluxing the as-prepared colloid at or near the boiling point of the solvent in the presence of a passivating agent, dodecanethiol resulted in a previously reported Pd-thiolate cluster, [Pd(SC{sub 12}H{sub 25}){sub 2}]{sub 6} but did not render the expected narrowing down of the particle size distribution. Solventless thermolysis of the Pd-thiolate complex resulted in various Pd systems such as Pd(0), PdS, and Pd-PdO core-shell nanoparticles thus demonstrating its versatility. These Pd nanostructures have been characterized using high-resolution electron microscopy and powder X-ray diffraction methods. - Graphical abstract: Solventless thermolysis of a single palladium-thiolate cluster affords various Pd systems such as Pd(0), Pd-PdO core-shell, and PdS nanoparticles demonstrating the versatility of the precursor and the methodology.

  13. Ni Ni: University of California - Los Angeles

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ni Ni: University of California - Los Angeles Alumni Link: Opportunities, News and Resources for Former Employees Latest Issue:September 2015 all issues All Issues » submit Ni Ni: University of California - Los Angeles Condensed matter January 1, 2015 Ni Ni Ni Ni Contact Linda Anderman Email Ni Ni Ni Ni now at the University of California-Los Angeles After finishing her work at Princeton, Ni Ni began at the Lab as a postdoc in 2012 with the Condensed Matter and Magnetic Science Group. Ni was

  14. Electronic structure of the heavy-fermion caged compound Ce3Pd20X6(X=Si,Ge) studied by density functional theory and photoelectron spectroscopy

    SciTech Connect (OSTI)

    Yamaoka, Hitoshi; Schwier, Eike F.; Arita, Masashi; Shimada, Kenya; Tsujii, Naohito; Jarrige, Ignace; Jiang, Jian; Hayashi, Hirokazu; Iwasawa, Hideaki; Namatame, Hirofumi; Taniguchi, Masaki; Kitazawa, Hideaki

    2015-03-30

    The electronic structure of Ce₃Pd₂₀X₆ (X = Si, Ge) has been studied using detailed density functional theory (DFT) calculations and high-resolution photoelectron spectroscopy (PES) measurements. The orbital decomposition of the electronic structure by DFT calculations indicates that Ce atoms at the (8c) site surrounded by 16 Pd atoms have a more localized nature and a tendency to be magnetic. Ce atoms in the (4a) site surrounded by 12 Pd and 6 X atoms, on the other, show only a negligible magnetic moment. In the photoemission valence-band spectra we observe a strong f⁰ (Ce⁴⁺) component with a small fraction of f¹ (Ce³⁺) component. The spectral weight of f¹ component near the Fermi level Ce₃Pd₂₀Si₆ is stronger than that for Ce₃Pd₂₀Ge₆ at the 4d-4f resonance, suggesting stronger c-f hybridization in the former. This may hint to the origin of the large electronic specific coefficient of Ce₃Pd₂₀Si₆ compared to Ce₃Pd₂₀Ge₆.

  15. Carbon-Supported bimetallic Pd-Fe catalysts for vapor-phase hydrodeoxygenation of guaiacol

    SciTech Connect (OSTI)

    Sun, Junming; Karim, Ayman M.; Zhang, He; Kovarik, Libor; Li, Xiaohong S.; Hensley, Alyssa; McEwen, Jean-Sabin; Wang, Yong

    2013-10-01

    Abstract Carbon supported metal catalysts (Cu/C, Fe/C, Pd/C, Pt/C, PdFe/C and Ru/C) have been prepared, characterized and tested for vapor-phase hydrodeoxygenation (HDO) of guaiacol (GUA) at atmospheric pressure. Phenol was the major intermediate on all catalysts. Over the noble metal catalysts saturation of the aromatic ring was the major pathway observed at low temperature (250 C), forming predominantly cyclohexanone and cyclohexanol. Substantial ring opening reaction was observed on Pt/C and Ru/C at higher reaction temperatures (e.g., 350 C). Base metal catalysts, especially Fe/C, were found to exhibit high HDO activity without ring-saturation or ring-opening with the main products being benzene, phenol along with small amounts of cresol, toluene and trimethylbenzene (TMB). A substantial enhancement in HDO activity was observed on the PdFe/C catalysts. Compared with Fe/C, the yield to oxygen-free aromatic products (i.e., benzene/toluene/TMB) on PdFe/C increased by a factor of four at 350 C, and by approximately a factor of two (83.2% versus 43.3%) at 450 C. The enhanced activity of PdFe/C is attributed to the formation of PdFe alloy as evidenced by STEM, EDS and TPR.

  16. Stabilization of Pt monolayer catalysts under harsh conditions of fuel cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Xiaoming; Liu, Ping; Yu, Shansheng; Qiao, Liang; Zheng, Weitao

    2015-05-21

    We employed density functional theory (DFT) to explore the stability of core (M = Cu, Ru, Rh, Pd, Ag, Os, Ir, Au)-shell (Pt) catalysts under harsh conditions, including solutions and reaction intermediates involved in the oxygen reduction reaction (ORR) in fuel cells. A pseudomorphic surface alloy (PSA) with a Pt monolayer (Pt1ML) supported on an M surface, Pt1ML/M(111) or (001), was considered as a model system. Different sets of candidate M cores were identified to achieve a stable Pt1ML shell depending on the conditions. In vacuum conditions, the Pt1ML shell can be stabilized on the most of M cores exceptmore » Cu, Ag, and Au. The situation varies under various electrochemical conditions. Depending on the solutions and the operating reaction pathways of the ORR, different M should be considered. Pd and Ir are the only core metals studied, being able to keep the PtML shell intact in perchloric acid, sulfuric acid, phosphoric acid, and alkaline solutions as well as under the ORR conditions via different pathways. Ru and Os cores should also be paid attention, which only fall during the ORR via the *OOH intermediate. Rh core works well as long as the ORR does not undergo the pathway via *O intermediate. Our results show that PSAs can behave differently from the near surface alloy, Pt1ML/M1ML/Pt(111), highlighting the importance of considering both chemical environments and the atomic structures in rational design of highly stable core-shell nanocatalysts. Finally, the roles that d-band center of a core M played in determining the stability of supported Pt1ML shell were also discussed.« less

  17. Stabilization of Pt monolayer catalysts under harsh conditions of fuel cells

    SciTech Connect (OSTI)

    Zhang, Xiaoming; Liu, Ping; Yu, Shansheng; Qiao, Liang; Zheng, Weitao

    2015-05-21

    We employed density functional theory (DFT) to explore the stability of core (M = Cu, Ru, Rh, Pd, Ag, Os, Ir, Au)-shell (Pt) catalysts under harsh conditions, including solutions and reaction intermediates involved in the oxygen reduction reaction (ORR) in fuel cells. A pseudomorphic surface alloy (PSA) with a Pt monolayer (Pt1ML) supported on an M surface, Pt1ML/M(111) or (001), was considered as a model system. Different sets of candidate M cores were identified to achieve a stable Pt1ML shell depending on the conditions. In vacuum conditions, the Pt1ML shell can be stabilized on the most of M cores except Cu, Ag, and Au. The situation varies under various electrochemical conditions. Depending on the solutions and the operating reaction pathways of the ORR, different M should be considered. Pd and Ir are the only core metals studied, being able to keep the PtML shell intact in perchloric acid, sulfuric acid, phosphoric acid, and alkaline solutions as well as under the ORR conditions via different pathways. Ru and Os cores should also be paid attention, which only fall during the ORR via the *OOH intermediate. Rh core works well as long as the ORR does not undergo the pathway via *O intermediate. Our results show that PSAs can behave differently from the near surface alloy, Pt1ML/M1ML/Pt(111), highlighting the importance of considering both chemical environments and the atomic structures in rational design of highly stable core-shell nanocatalysts. Finally, the roles that d-band center of a core M played in determining the stability of supported Pt1ML shell were also discussed.

  18. Stabilization of Pt monolayer catalysts under harsh conditions of fuel cells

    SciTech Connect (OSTI)

    Zhang, Xiaoming; Yu, Shansheng; Zheng, Weitao E-mail: pingliu3@bnl.gov; Qiao, Liang; Liu, Ping E-mail: pingliu3@bnl.gov

    2015-05-21

    We employed density functional theory to explore the stability of core (M = Cu, Ru, Rh, Pd, Ag, Os, Ir, Au)-shell (Pt) catalysts under harsh conditions, including solutions and reaction intermediates involved in the oxygen reduction reaction (ORR) in fuel cells. A pseudomorphic surface alloy (PSA) with a Pt monolayer (Pt{sub 1ML}) supported on an M surface, Pt{sub 1ML}/M(111) or (001), was considered as a model system. Different sets of candidate M cores were identified to achieve a stable Pt{sub 1ML} shell depending on the conditions. In vacuum conditions, the Pt{sub 1ML} shell can be stabilized on the most of M cores except Cu, Ag, and Au. The situation varies under various electrochemical conditions. Depending on the solutions and the operating reaction pathways of the ORR, different M should be considered. Pd and Ir are the only core metals studied, being able to keep the Pt{sub ML} shell intact in perchloric acid, sulfuric acid, phosphoric acid, and alkaline solutions as well as under the ORR conditions via different pathways. Ru and Os cores should also be paid attention, which only fall during the ORR via the *OOH intermediate. Rh core works well as long as the ORR does not undergo the pathway via *O intermediate. Our results show that PSAs can behave differently from the near surface alloy, Pt{sub 1ML}/M{sub 1ML}/Pt(111), highlighting the importance of considering both chemical environments and the atomic structures in rational design of highly stable core-shell nanocatalysts. Finally, the roles that d-band center of a core M played in determining the stability of supported Pt{sub 1ML} shell were also discussed.

  19. Synthesis of Pt–Pd Core–Shell Nanostructures by Atomic Layer Deposition: Application in Propane Oxidative Dehydrogenation to Propylene

    SciTech Connect (OSTI)

    Lei, Yu; Liu, Bin; Lu, Junling; Lobo-Lapidus, Rodrigo J.; Wu, Tianpin; Feng, Hao; Xia, Xiaoxing; Mane, Anil U.; Libera, Joseph A.; Greeley, Jeffrey P.; Miller, Jeffrey T.; Elam, Jeffrey W.

    2012-08-20

    Atomic layer deposition (ALD) was employed to synthesize supported Pt–Pd bimetallic particles in the 1 to 2 nm range. The metal loading and composition of the supported Pt–Pd nanoparticles were controlled by varying the deposition temperature and by applying ALD metal oxide coatings to modify the support surface chemistry. High-resolution scanning transmission electron microscopy images showed monodispersed Pt–Pd nanoparticles on ALD Al2O3- and TiO2-modified SiO2 gel. X-ray absorption spectroscopy revealed that the bimetallic nanoparticles have a stable Pt-core, Pd-shell nanostructure. Density functional theory calculations revealed that the most stable surface configuration for the Pt–Pd alloys in an H2 environment has a Pt-core, Pd-shell nanostructure. Finally, in comparison to their monometallic counterparts, the small Pt–Pd bimetallic core–shell nanoparticles exhibited higher activity in propane oxidative dehydrogenation as compared to their physical mixture.

  20. Preparation and Characterization of PdFe Nanoleaves as Electrocatalysts for Oxygen Reduction Reaction

    SciTech Connect (OSTI)

    More, Karren Leslie; Wu, Zili

    2011-01-01

    Novel PdFe-nanoleaves (NLs) have been prepared through a wet chemistry-based solution phase reduction synthesis route. High-resolution transmission electron microscopy (HR-TEM) and scanning transmission electron microscopy (S/TEM) coupled with high-spatial-resolution compositional analysis clearly show this newly-developed structure is assembled from Pd-rich nanowires (NWs) surrounded by Fe-rich sheets. The Pd-NWs have a diameter in the range of 1.8-2.3 nm and a large electrochemical surface area of >50 m2/g. Their length (30 - 100 nm) and morphology can be tuned by altering the nanostructure synthesis conditions and the Fe amount in the NLs. With increasing Fe content, thinner and longer sheet-enveloped nanowires can be prepared. The side surfaces of Pd-NWs observed by HR-TEM are predominantly Pd (111) facets, while the tips and ends are Pd (110) and Pd (100) facets. By etching away the enveloping Fe-rich sheets using an organic acid, the Pd-rich NWs are exposed on the surfaces of the nanoleaves, and they demonstrate high reactivity towards electrocatalytic reduction of oxygen in a 0.1 M NaOH electrolyte, i.e., 3.0 increase in the specific activity and 2.7 increase in the mass activity compared with a commercial Pt/C catalyst (at 0 V vs. Hg/HgO). The electrocatalytic activity enhancement can be attributed to the unique nanoleave structure that provides more Pd (111) facets, a large surface area, and more resistance to Pd oxide formation.

  1. Pt monolayer shell on nitrided alloy core — A path to highly stable oxygen reduction catalyst

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hu, Jue; Kuttiyiel, Kurian A.; Sasaki, Kotaro; Su, Dong; Yang, Tae -Hyun; Park, Gu -Gon; Zhang, Chengxu; Chen, Guangyu; Adzic, Radoslav R.

    2015-07-22

    The inadequate activity and stability of Pt as a cathode catalyst under the severe operation conditions are the critical problems facing the application of the proton exchange membrane fuel cell (PEMFC). Here we report on a novel route to synthesize highly active and stable oxygen reduction catalysts by depositing Pt monolayer on a nitrided alloy core. The prepared PtMLPdNiN/C catalyst retains 89% of the initial electrochemical surface area after 50,000 cycles between potentials 0.6 and 1.0 V. By correlating electron energy-loss spectroscopy and X-ray absorption spectroscopy analyses with electrochemical measurements, we found that the significant improvement of stability of themore » PtMLPdNiN/C catalyst is caused by nitrogen doping while reducing the total precious metal loading.« less

  2. Elastic properties of Pd-hydrogen, Pd-deuterium, and Pd-tritium single crystals

    SciTech Connect (OSTI)

    Schwarz, R.B. . E-mail: rxzs@lanl.gov; Bach, H.T.; Harms, U.; Tuggle, D.

    2005-02-01

    We used a resonant-ultrasound-spectroscopy technique to measure the three independent elastic constants of PdH{sub x}, PdD{sub x}, and PdT{sub x} single crystals at 300 K. For 0.1x0.62 our PdH{sub x} crystals are two-phase mixtures of coherent {alpha} and {beta} hydride phases. For increasing x in this range, C{sub 44} decreases monotonically whereas C'=12(C11-C12) has a concave parabolic dependence. This difference is because C' is softened by an anelastic relaxation resulting from acoustic-stress-induced changes in the shape of the coherent lenticular-shape precipitates ({beta}-hydride precipitates in {alpha}-hydride matrix and {alpha}-hydride precipitates in {beta}-hydride matrix). In the {beta}-phase C' and C{sub 44} decrease with increasing hydrogen (or deuterium or tritium) content. Furthermore, C' exhibits a strong isotope effect whereas C{sub 44} does not. This effect is attributed to differences in the excitation of optical phonons in Pd-H, Pd-D and Pd-T.

  3. Pd/Ni-WO3 anodic double layer gasochromic device

    DOE Patents [OSTI]

    Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland; Liu, Ping

    2004-04-20

    An anodic double layer gasochromic sensor structure for optical detection of hydrogen in improved response time and with improved optical absorption real time constants, comprising: a glass substrate; a tungsten-doped nickel oxide layer coated on the glass substrate; and a palladium layer coated on the tungsten-doped nickel oxide layer.

  4. ALTERNATIVE MATERIALS TO PD MEMBRANES FOR HYDROGEN PURIFICATION

    SciTech Connect (OSTI)

    Adams, T; Paul Korinko, P

    2007-11-13

    Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focal point of the reported work was to evaluate two different classes of materials for potential replacement of conventional Pd-alloy purification/diffuser membranes. Crystalline V-Ni-Ti and Amorphous Fe- and Co-based metallic glass alloys have been evaluated using both electrochemical and gaseous hydrogen permeation testing techniques..

  5. ALTERNATIVE MATERIALS TO PD MEMBRANES FOR HYDROGEN PURIFICATION

    SciTech Connect (OSTI)

    Korinko, P; T. Adams

    2008-09-12

    Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focal point of the reported work was to evaluate two different classes of materials for potential replacement of conventional Pd-alloy purification/diffuser membranes. Crystalline V-Ni-Ti and Amorphous Fe- and Co-based metallic glass alloys have been evaluated using gaseous hydrogen permeation testing techniques.

  6. Synthesis and crystal structure of the palladium oxides NaPd{sub 3}O{sub 4}, Na{sub 2}PdO{sub 3} and K{sub 3}Pd{sub 2}O{sub 4}

    SciTech Connect (OSTI)

    Panin, Rodion V. Khasanova, Nellie R.; Abakumov, Artem M.; Antipov, Evgeny V.; Tendeloo, Gustaaf van; Schnelle, Walter

    2007-05-15

    NaPd{sub 3}O{sub 4}, Na{sub 2}PdO{sub 3} and K{sub 3}Pd{sub 2}O{sub 4} have been prepared by solid-state reaction of Na{sub 2}O{sub 2} or KO{sub 2} and PdO in sealed silica tubes. Crystal structures of the synthesized phases were refined by the Rietveld method from X-ray powder diffraction data. NaPd{sub 3}O{sub 4} (space group Pm3-barn, a=5.64979(6) A, Z=2) is isostructural to NaPt{sub 3}O{sub 4}. It consists of NaO{sub 8} cubes and PdO{sub 4} squares, corner linked into a three-dimensional framework where the planes of neighboring PdO{sub 4} squares are perpendicular to each other. Na{sub 2}PdO{sub 3} (space group C2/c, a=5.3857(1) A, b=9.3297(1) A, c=10.8136(2) A, {beta}=99.437(2){sup o}, Z=8) belongs to the Li{sub 2}RuO{sub 3}-structure type, being the layered variant of the NaCl structure, where the layers of octahedral interstices filled with Na{sup +} and Pd{sup 4+} cations alternate with Na{sub 3} layers along the c-axis. Na{sub 2}PdO{sub 3} exhibits a stacking disorder, detected by electron diffraction and Rietveld refinement. K{sub 3}Pd{sub 2}O{sub 4}, prepared for the first time, crystallizes in the orthorhombic space group Cmcm (a=6.1751(6) A, b=9.1772(12) A, c=11.3402(12) A, Z=4). Its structure is composed of planar PdO{sub 4} units connected via common edges to form parallel staggered PdO{sub 2} strips, where potassium atoms are located between them. Magnetic susceptibility measurements of K{sub 3}Pd{sub 2}O{sub 4} reveal a Curie-Weiss behavior in the temperature range above 80 K. - Graphical abstract: Na{sub 2}PdO{sub 3} (space group C2/c, a=5.3857(1) A, b=9.3297(1) A, c=10.8136(2) A, {beta}=99.437(2), Z=8) belongs to the Li{sub 2}RuO{sub 3}-structure type, being the layered variant of the NaCl structure, where the layers of octahedral interstices filled with Na{sup +} and Pd{sup 4+} cations (NaPd{sub 2}O{sub 6} slabs) alternate with Na{sub 3} layers along the c-axis.

  7. Multi-functional ultrathin PdxCu1-x and Pt~PdxCu1-x one-dimensional nanowire motifs for various small molecule oxidation reactions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Haiqing; Wong, Stanislaus S.; Adzic, Radoslav R.

    2015-11-18

    Developing novel electrocatalysts for small molecule oxidation processes, including formic acid oxidation (FAOR), methanol oxidation reaction (MOR), and ethanol oxidation reaction (EOR), denoting the key anodic reactions for their respective fuel cell configurations, is a significant and relevant theme of recent efforts in the field. Herein, in this report, we demonstrated a concerted effort to couple and combine the benefits of small size, anisotropic morphology, and tunable chemical composition in order to devise a novel “family” of functional architectures. In particular, we have fabricated not only ultrathin 1-D Pd1–xCux alloys but also Pt-coated Pd1–xCux (i.e., Pt~Pd1–xCux; herein the ~ indicatesmore » an intimate association, but not necessarily actual bond formation, between the inner bimetallic core and the Pt outer shell) core–shell hierarchical nanostructures with readily tunable chemical compositions by utilizing a facile, surfactant-based, wet chemical synthesis coupled with a Cu underpotential deposition technique. Our main finding is that our series of as-prepared nanowires are functionally flexible. More precisely, we demonstrate that various examples within this “family” of structural motifs can be tailored for exceptional activity with all 3 of these important electrocatalytic reactions. In particular, we note that our series of Pd1–xCux nanowires all exhibit enhanced FAOR activities as compared with not only analogous Pd ultrathin nanowires but also commercial Pt and Pd standards, with Pd9Cu representing the “optimal” composition. Moreover, our group of Pt~Pd1–xCux nanowires consistently outperformed not only commercial Pt NPs but also ultrathin Pt nanowires by several fold orders of magnitude for both the MOR and EOR reactions in alkaline media. As a result, the variation of the MOR and EOR performance with the chemical composition of our ultrathin Pt~Pd1–xCux nanowires was also discussed.« less

  8. Asymmetric magnetic proximity effect in a Pd/Co/Pd trilayer system (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Asymmetric magnetic proximity effect in a Pd/Co/Pd trilayer system Citation Details In-Document Search Title: Asymmetric magnetic proximity effect in a Pd/Co/Pd trilayer system In spintronic devices consisting of ferromagnetic/nonmagnetic systems, the ferromagnet-induced magnetic moment in the adjacent nonmagnetic material significantly influences the spin transport properties. In this study, such magnetic proximity effect in a Pd/Co/Pd trilayer system is

  9. High Tc YBCO superconductor deposited on biaxially textured Ni substrate

    DOE Patents [OSTI]

    Budai, John D.; Christen, David K.; Goyal, Amit; He, Qing; Kroeger, Donald M.; Lee, Dominic F.; List, III, Frederick A.; Norton, David P.; Paranthaman, Mariappan; Sales, Brian C.; Specht, Eliot D.

    1999-01-01

    A superconducting article includes a biaxially-textured Ni substrate, and epitaxial buffer layers of Pd (optional), CeO.sub.2 and YSZ, and a top layer of in-plane aligned, c-axis oriented YBCO having a critical current density (J.sub.c) in the range of at least 100,000 A/cm.sup.2 at 77 K.

  10. Room temperature synthesis of Ni-based alloy nanoparticles by radiolysis.

    SciTech Connect (OSTI)

    Nenoff, Tina Maria; Berry, Donald T.; Lu, Ping; Leung, Kevin; Provencio, Paula Polyak; Stumpf, Roland Rudolph; Huang, Jian Yu; Zhang, Zhenyuan

    2009-09-01

    Room temperature radiolysis, density functional theory, and various nanoscale characterization methods were used to synthesize and fully describe Ni-based alloy nanoparticles (NPs) that were synthesized at room temperature. These complementary methods provide a strong basis in understanding and describing metastable phase regimes of alloy NPs whose reaction formation is determined by kinetic rather than thermodynamic reaction processes. Four series of NPs, (Ag-Ni, Pd-Ni, Co-Ni, and W-Ni) were analyzed and characterized by a variety of methods, including UV-vis, TEM/HRTEM, HAADF-STEM and EFTEM mapping. In the first focus of research, AgNi and PdNi were studied. Different ratios of Ag{sub x}- Ni{sub 1-x} alloy NPs and Pd{sub 0.5}- Ni{sub 0.5} alloy NP were prepared using a high dose rate from gamma irradiation. Images from high-angle annular dark-field (HAADF) show that the Ag-Ni NPs are not core-shell structure but are homogeneous alloys in composition. Energy filtered transmission electron microscopy (EFTEM) maps show the homogeneity of the metals in each alloy NP. Of particular interest are the normally immiscible Ag-Ni NPs. All evidence confirmed that homogeneous Ag-Ni and Pd-Ni alloy NPs presented here were successfully synthesized by high dose rate radiolytic methodology. A mechanism is provided to explain the homogeneous formation of the alloy NPs. Furthermore, studies of Pd-Ni NPs by in situ TEM (with heated stage) shows the ability to sinter these NPs at temperatures below 800 C. In the second set of work, CoNi and WNi superalloy NPs were attempted at 50/50 concentration ratios using high dose rates from gamma irradiation. Preliminary results on synthesis and characterization have been completed and are presented. As with the earlier alloy NPs, no evidence of core-shell NP formation occurs. Microscopy results seem to indicate alloying occurred with the CoNi alloys. However, there appears to be incomplete reduction of the Na{sub 2}WO{sub 4} to form the W

  11. Overall Photocatalytic Water Splitting with NiOx-SrTiO3 A Revised Mechanism

    SciTech Connect (OSTI)

    Townsend, Troy K.; Browning, Nigel D.; Osterloh, Frank

    2012-11-01

    NiOx (0 < x < 1) modified SrTiO3 (STO) is one of the best studied photocatalyst for overall water splitting under UV light. The established mechanism for this and many other NiOx containing catalysts assumes water oxidation to occur at the early transition metal oxide and water reduction at NiOx. Here we show that NiOx-STO is more likely a three component Ni-STO-NiO catalyst, in which STO absorbs the light, Ni reduces protons, and NiO oxidizes water. This interpretation is based on systematic H2/O2 evolution tests of appropriately varied catalyst compositions using oxidized, chemically and photochemically added nickel and NiO nanoparticle cocatalysts. Surface photovoltage (SPV) measurements reveal that Ni(0) serves as an electron trap (site for water reduction) and that NiO serves as a hole trap (site for water oxidation). Electrochemical measurements show that the overpotential for water oxidation correlates with NiO content, whereas the water reduction overpotential depends on Ni content. Photodeposition experiments with NiCl2 and H2PtCl6 on NiO-STO show that electrons are available on the STO surface, not on the NiO particles. Based on photoelectrochemistry, both NiO and Ni particles suppress the Fermi level in STO, but the effect of this shift on catalytic activity is not clear. Overall, the results suggest a revised role for NiO in NiOx-STO and in many other nickel-containing water splitting systems, including NiOx-La:KTaO3, and many layered perovskites.

  12. Formation of PtSi Schottky barrier MOSFETs using plasma etching

    SciTech Connect (OSTI)

    Woo, Young Min; Hwang, Wan Sik; Yoo, Won Jong

    2015-03-15

    PtSi Schottky barrier (SB) MOSFETs were fabricated and their device performance was characterized. PtSi was selected instead of NiSi to form the p-type SB junction since such a configuration would be easy to fabricate through SF{sub 6} based plasma etching. The addition of He-O{sub 2} in SF{sub 6} decreases the etching rate of PtSi while the etching rate of Pt remains unchanged. The retardation in the etching rate of PtSi in He-O{sub 2}/SF{sub 6} is attributed to the formation of a metal oxide on the etched PtSi surface, as evidenced by the x-ray photoelectron spectroscopy results. Optical emission spectroscopy was conducted to establish the endpoint where the wavelength from the feed gas was traced instead of tracing the etching by-products since the by-products have little association with the plasma reaction. The I{sub DS}V{sub DS} curves at various V{sub G}V{sub TH} indicate that plasma etching resulted in the successful removal of the Pt on the sidewall region, with negligible damage to the S/D area.

  13. Blending Cr2O3 into a NiO-Ni electrocatalyst for sustained water splitting

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gong, Ming; Zhou, Wu; Kenney, Michael James; Kapusta, Rich; Cowley, Sam; Wu, Yingpeng; Lu, Bingan; Lin, Meng -Chang; Wang, Di -Yan; Yang, Jiang; et al

    2015-08-24

    The rising H2 economy demands active and durable electrocatalysts based on low-cost, earth-abundant materials for water electrolysis/photolysis. Here we report nanoscale Ni metal cores over-coated by a Cr2O3-blended NiO layer synthesized on metallic foam substrates. The Ni@NiO/Cr2O3 triphase material exhibits superior activity and stability similar to Pt for the hydrogen-evolution reaction in basic solutions. The chemically stable Cr2O3 is crucial for preventing oxidation of the Ni core, maintaining abundant NiO/Ni interfaces as catalytically active sites in the heterostructure and thus imparting high stability to the hydrogen-evolution catalyst. The highly active and stable electrocatalyst enables an alkaline electrolyzer operating at 20more » mA cm–2 at a voltage lower than 1.5 V, lasting longer than 3 weeks without decay. Thus, the non-precious metal catalysts afford a high efficiency of about 15 % for light-driven water splitting using GaAs solar cells.« less

  14. Phase equilibria, formation, crystal and electronic structure of ternary compounds in Ti-Ni-Sn and Ti-Ni-Sb ternary systems

    SciTech Connect (OSTI)

    Romaka, V.V.; Rogl, P.; Romaka, L.; Stadnyk, Yu.; Melnychenko, N.; Grytsiv, A.; Falmbigl, M.; Skryabina, N.

    2013-01-15

    The phase equilibria of the Ti-Ni-Sn and Ti-Ni-Sb ternary systems have been studied in the whole concentration range by means of X-ray and EPM analyses at 1073 K and 873 K, respectively. Four ternary intermetallic compounds TiNiSn (MgAgAs-type), TiNi{sub 2-x}Sn (MnCu{sub 2}Al-type), Ti{sub 2}Ni{sub 2}Sn (U{sub 2}Pt{sub 2}Sn-type), and Ti{sub 5}NiSn{sub 3} (Hf{sub 5}CuSn{sub 3}-type) are formed in Ti-Ni-Sn system at 1073 K. The TiNi{sub 2}Sn stannide is characterized by homogeneity in the range of 50-47 at% of Ni. The Ti-Ni-Sb ternary system at 873 K is characterized by formation of three ternary intermetallic compounds, Ti{sub 0.8}NiSb (MgAgAs-type), Ti{sub 5}Ni{sub 0.45}Sb{sub 2.55} (W{sub 5}Si{sub 3}-type), and Ti{sub 5}NiSb{sub 3} (Hf{sub 5}CuSn{sub 3}-type). The solubility of Ni in Ti{sub 0.8}NiSb decreases number of vacancies in Ti site up to Ti{sub 0.91}Ni{sub 1.1}Sb composition. - Graphical abstract: Isothermal section of the Ti-Ni-Sn phase diagram and DOS distribution in hypothetical TiNi{sub 1+x}Sn solid solution. Highlights: Black-Right-Pointing-Pointer Ti-Ni-Sn phase diagram was constructed at 1073 K. Black-Right-Pointing-Pointer Four ternary compounds are formed: TiNiSn, TiNi{sub 2-x}Sn, Ti{sub 2}Ni{sub 2}Sn, and Ti{sub 5}NiSn{sub 3}. Black-Right-Pointing-Pointer Three ternary compounds exist in Ti-Ni-Sb system at 873 K. Black-Right-Pointing-Pointer The TiNi{sub 2}Sb compound is absent.

  15. Preparation and Characterization of PdFe Nanoleaves as Electrocatalyst...

    Office of Scientific and Technical Information (OSTI)

    The side surfaces of Pd-NWs observed by HR-TEM are predominantly Pd (111) facets, while ... acid, the Pd-rich NWs are exposed on the surfaces of the nanoleaves, and they demonstrate ...

  16. Palladium site ordering and the occurrence of superconductivity in Bi{sub 2}Pd{sub 3}Se{sub 2-x}S{sub x}

    SciTech Connect (OSTI)

    Weihrich, R.; Matar, S.F.; Anusca, I.; Pielnhofer, F.; Peter, P.; Bachhuber, F.; Eyert, V.

    2011-04-15

    The crystallographic and electronic structures of compounds related to parkerite (Bi{sub 2}Ni{sub 3}S{sub 2}) are investigated with respect to the recently reported occurrence (Bi{sub 2}Pd{sub 3}Se{sub 2}) and absence (Bi{sub 2}Pd{sub 3}S{sub 2}) of superconductivity. Similarities and differences of the crystal structures are discussed within the series of solid solutions Bi{sub 2}Pd{sub 3}S{sub 2-x}Se{sub x} from powder and single crystal diffraction data. From crystal structure refinements, the question of different structures and settings of parkerite is discussed. Similar and different 2D and 3D partial Pd-Ch (Ch=S, Se) structures are related to half antiperovskite ordering schemes. To investigate the relation of low dimensional structures and the occurrence of superconductivity, electronic structures are analyzed by scalar-relativistic DFT calculations, including site projected DOS, ECOV and Fermi surfaces. -- Graphical abstract: Structure relations for perovskite type BiPd{sub 3}C, BiPd{sub 3/2}Se and BiPd{sub 3/2}S. Display Omitted Research highlights: {yields} Merging crystallographic and electronic structures studies to understand chalcogenides related to parkerite (Bi{sub 2}Ni{sub 3}S{sub 2}). {yields} Investigation in view of recently reported occurrence (Bi{sub 2}Pd{sub 3}Se{sub 2}) and absence (Bi{sub 2}Pd{sub 3}S{sub 2}) of superconductivity. {yields} Relationship of half perovskites with perovskites.

  17. Synthesis of Pt-Pd Core-Shell Nanostructures by Atomic Layer...

    Office of Scientific and Technical Information (OSTI)

    and by applying ALD metal oxide coatings to modify the support surface chemistry. ... Resource Type: Journal Article Resource Relation: Journal Name: Chemistry of Materials; ...

  18. A photoemission study of Pd ultrathin films on Pt(111) (Journal...

    Office of Scientific and Technical Information (OSTI)

    Authors: Mun, Bongjin Simon ; Lee, Choongman ; Stamenkovic, Vojislav ; Markovic, Nenad M. ; Ross Jr., Philip N. Publication Date: 2005-05-11 OSTI Identifier: 860351 Report ...

  19. Formation of Pd/Au Nanostructures from Pd Nanowires via Galvanic Replacement Reaction

    SciTech Connect (OSTI)

    Teng,X.; Wang, Q.; Liu, P.; Han, W.; Frenkel, A.; Wen, W.; Marinkovic, N.; Hanson, J.; Rodriguez, J.

    2008-01-01

    Bimetallic nanostructures with non-random metal atoms distribution are very important for various applications. To synthesize such structures via benign wet chemistry approach remains challenging. This paper reports a synthesis of a Au/Pd alloy nanostructure through the galvanic replacement reaction between Pd ultrathin nanowires (2.4 {+-} 0.2 nm in width, over 30 nm in length) and AuCl3 in toluene. Both morphological and structural changes were monitored during the reaction up to 10 h. Continuous changes of chemical composition and crystalline structure from Pd nanowires to Pd68Au32 and Pd45Au55 alloys, and to Au nanoparticles were observed. More interestingly, by using combined techniques such as high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), UV-vis absorption, and extended X-ray absorption fine structure (EXAFS) spectroscopy, we found the formation of Pd68Au32 non-random alloy with Au-rich core and Pd-rich shell, and random Pd45Au55 alloy with uniformly mixed Pd and Au atom inside the nanoparticles, respectively. Density functional theory (DFT) calculations indicated that alkylamine will strongly stabilize Pd to the surface, resulting in diffusion of Au atoms into the core region to form a non-random alloy. We believe such benign synthetic techniques can also enable the large scale preparation of various types of non-random alloys for several technically important catalysis applications.

  20. Pt Reyes 2005: MASRAD, MASE

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Stratus Radiation, Aerosol, and Drizzle MASRAD, MASE Graham Feingold, A. McComiskey M. Miller * , D. Turner, P. Daum, J. Seinfeld, J. Ogren Q. Min, C. Berkowitz, J. Wang, E. Andrews, C. Chiu, M. Jensen, N. Riemer , J. Ching, L. Berg, A. S. Frisch, M. Bartholomew, B. Kim, M. Dunn, P. Kollias, B. Albrecht, ....... Pt. Reyes, California *PI Motivation: Strong shortwave cloud forcing (dark underlying ocean) No compensating longwave forcing Open cells Pockets of open cells Closed cells Science Goals

  1. Alternation of the Pd Lattice in Nano-Sized-Pd/ZrO2 Composite during Hydrogen Absorption

    SciTech Connect (OSTI)

    Arachi, Yoshinori; Asai, Takeshi; Emura, Shuichi; Omura, Akira; Nunogaki, Masanobu; Yamaura, Shunichi; Inoue, Akihisa; Arata, Yoshiaki

    2007-02-02

    Structural analysis of high Deuterium absorbed 5 nm Pd particles in dispersed ZrO2 has been carried out using XAFS techniques. X-ray absorption spectra around the Pd K-absorption edge were observed and analyzed. The Pd-Pd bonding distance in the fcc Pd lattice was enlarged by 0.08 {approx} 0.09 A during absorption of deuterium, and it completely reverted to its original state with the release of deuterium while maintaining the crystal lattice symmetry. These changes provide evidence that deuterium locates not on the surface of the Pd particle, but rather within the Pd crystal lattice. XANES spectra clearly indicate that any change in the oxidation state of Pd are not observed, resulting in no reaction of the absorbed Deuterium atoms with Pd atoms. This paper reports the alternation of Pd lattice in nano-sized composite during hydrogen absorption. The possible models of deuterium position in the Pd lattice are also discussed.

  2. Influence of valence electron concentration on Laves phases: Structures and phase stability of pseudo-binary MgZn2-xPdx

    SciTech Connect (OSTI)

    Thimmaiah, Srinivasa; Miller, Gordon J.

    2015-06-03

    A series of pseudo-binary compounds MgZn2-xPdx (0.15 ? x ? 1.0) were synthesized and structurally characterized to understand the role of valence electron concentration (vec) on the prototype Laves phase MgZn2 with Pd-substitution. Three distinctive phase regions were observed with respect to Pd content, all exhibiting fundamental Laves phase structures: 0.1 ? x ? 0.3 (MgNi2-type, hP24; MgZn1.80Pd0.20(2)), 0.4 ? x ? 0.6 (MgCu2-type, cF24; MgZn1.59Pd0.41(2)), and 0.62 ? x ? 0.8 (MgZn2-type, hP12: MgZn1.37Pd0.63(2)). Refinements from single-crystal X-ray diffraction indicated nearly statistical distributions of Pd and Zn atoms among the majority atom sites in these structures. Interestingly, the MgZn2-type structure re-emerges in MgZn2xPdx at x ? 0.7 with the refined composition MgZn1.37(2)Pd0.63 and a c/a ratio of 1.59 compared to 1.64 for binary MgZn2. Electronic structure calculations on a model MgZn1.25Pd0.75 yielded a density of states (DOS) curve showing enhancement of a pseudogap at the Fermi level as a result of electronic stabilization due to the Pd addition. Moreover, integrated crystal orbital Hamilton population values show significant increases of orbital interactions for (Zn,Pd)(Zn,Pd) atom pairs within the majority atom substructure, i.e., within the Kagom nets as well as between a Kagom net and an apical site, from binary MgZn2 to the ternary MgZn1.25Pd0.75. Multi-centered bonding is evident from electron localization function plots for MgZn1.25Pd0.75, an outcome which is in accordance with analysis of other Laves phases.

  3. EXAMINATION OF 80 DEGREES C DESORPTION ISOTHERMS OFTRITIUM AGED PD/K AND LANA.75

    SciTech Connect (OSTI)

    Staack, G; Kirk Shanahan, K; Tom Walters, T; Roger Pilgrim, R

    2007-08-28

    Metal hydrides, specifically Pd deposited on kieselguhr (Pd/k) and LaNi{sub 4.25}Al{sub 0.75} (LANA.75), have been used at the Savannah River Site for almost twenty years for hydrogen isotope separation and storage. Radiolytic decay of tritium to helium-3 in the metal matrix causes three classic changes in the performance of the hydride: the plateau pressure decreases, the plateau slope increases, and a heel forms, reducing the reversible capacity of the hydride. Deuterium and tritium isotherms were collected on the virgin materials, only tritium isotherms were collected at approximately 2 years, and both deuterium and tritium isotherms were collected at approximately 3.5 years of quiescent aging. Points of interest include those mentioned above as well as the effects of cycling the materials. The methods and results are presented.

  4. The hydrogen permeability of Pd{sub 4}S

    SciTech Connect (OSTI)

    O'Brien, Casey; Miller, James; Gellman, Andrew; Morreale, Bryan

    2011-04-01

    Hydrogen permeates rapidly through pure Pd membranes, but H{sub 2}S, a common minor component in hydrogen-containing streams, produces a Pd{sub 4}S film on the Pd surface that severely retards hydrogen permeation. Hydrogen still permeates through the bi-layered Pd{sub 4}S/Pd structure, indicating that the Pd{sub 4}S surface is active for H{sub 2} dissociation; the low hydrogen permeability of the Pd4S film is responsible for the decreased rate of hydrogen transport. In this work, the hydrogen permeability of Pd{sub 4}S was determined experimentally in the 623-773 K temperature range. Bi-layered Pd{sub 4}S/Pd foils were produced by exposing pure Pd foils to H{sub 2}S. H{sub 2} fluxes through the bi-layered Pd{sub 4}S/Pd foils were measured during exposure to both pure H{sub 2} and a 1000 ppm H{sub 2}S in H{sub 2} gas mixture. Our results show that H{sub 2}S slows hydrogen permeation through Pd mainly by producing a Pd{sub 4}S film on the Pd surface that is roughly an order-of-magnitude less permeable to hydrogen (k{sub Pd{sub 4}S} = 10{sup ?7.5} exp(?0.22 eV/k{sub B}T) molH{sub 2}/m/s/Pa{sup 1/2}) than pure Pd. The presence of H{sub 2}S in the gas stream results in greater inhibition of hydrogen transport than can be explained by the very low permeability of Pd{sub 4}S. H{sub 2}S may block H2 dissociation sites at the Pd{sub 4}S surface.

  5. Converse magnetoelectric coupling in NiFe/Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}PbTiO{sub 3} nanocomposite thin films grown on Si substrates

    SciTech Connect (OSTI)

    Feng, Ming; Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000 ; Hu, Jiamian; Wang, Jianjun; Li, Zheng; Shu, Li; Nan, C. W.

    2013-11-04

    Multiferroic NiFe (?30 nm)/Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}PbTiO{sub 3}(PMNPT, ?220 nm) bilayered thin films were grown on common Pt/Ti/SiO{sub 2}/Si substrates by a combination of off-axis magnetron sputtering and sol-gel spin-coating technique. By using AC-mode magneto-optical Kerr effect technique, the change in the Kerr signal (magnetization) of the NiFe upon applying a low-frequency AC voltage to the PMNPT film was in situ acquired at zero magnetic field. The obtained Kerr signal versus voltage loop essentially tracks the electromechanical strain curve of the PMNPT thin film, clearly demonstrating a strain-mediated converse magnetoelectric coupling, i.e., voltage-modulated magnetization, in the NiFe/PMNPT nanocomposite thin films.

  6. Enhanced hydrogenation and reduced lattice distortion in size selected Pd-Ag and Pd-Cu alloy nanoparticles

    SciTech Connect (OSTI)

    Sengar, Saurabh K.; Mehta, B. R.; Kulriya, P. K.; Khan, S. A.

    2013-10-21

    Important correlation between valence band spectra and hydrogenation properties in Pd alloy nanoparticles is established by studying the properties of size selected and monocrystalline Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles. The X-ray photoelectron spectroscopy and elastic recoil detection analysis show that size induced Pd4d centroid shift is related to enhanced hydrogenation with H/Pd ratio of 0.57 and 0.49 in Pd-Ag and Pd-Cu nanoparticles in comparison to reported bulk values of 0.2 and 0.1, respectively. Pd-alloy nanoparticles show lower hydrogen induced lattice distortion. The reduced distortion and higher hydrogen reactivity of Pd-alloy nanoparticles is important for numerous hydrogen related applications.

  7. Direct evidence of anomalous interfacial magnetization in metamagnetic Pd doped FeRh thin films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bennett, S. P.; Ambaye, H.; Lee, H.; LeClair, P.; Mankey, G. J.; Lauter, V.

    2015-03-16

    Palladium doped iron rhodium is a magnetic material of significant interest for it’s close to room temperature magnetostructural phase transition from antiferromagnetic (AF) to ferromagnetic (FM) ordering. Here we report on the peculiarities of the magnetization distribution in thin films of FeRh(Pd) probed by Polarized Neutron Reflectometry. Remarkably, we’ve found thin interfacial regions with strong magnetization that have unique thermomagnetic properties as compared to the rest of the system. These regions exist at the top and bottom interfaces of the films while the central regions behave similarly to the bulk with a clear AF-FM order transition. Further we explore themore » impact of an additional Pt interlayer introduced in the middle of the FeRh(Pd) film and reveal that it serves to replicate the strong interfacial magnetization found at the top and bottom interfaces. In conclusion, these results are of great value both in understanding the fundamental physics of such an order transition, and in considering FeRh(Pd) for magnetic media and spintronics applications.« less

  8. Improving Stability and Activity of Pt Monolayer in Non-Pt Core-Shell Electrocatalysts

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    stability and activity of Pt monolayer and non-Pt core-shell electrocatalysts Radoslav Adzic, Kurian Kuttiyiel, Kotaro Sasaki, Miomir Vukmirovic, Yu Zhang, Jia Wang, Dong Su, Ping Liu, Yimei Zhu, Stoyan Bliznakov Brookhaven National Laboratory Catalysis Working Group, Meeting Los Alamos, January 21, 2015 Outline 1. Nitride-stabilized cores for improved activity / stability, and reduced Pt content in core-shell catalysts 2. Ordered non-Pt intermetallic compounds as cores and catalysts 3. Ordered

  9. Parity nonconservation in {sup 106}Pd and {sup 108}Pd neutron resonances

    SciTech Connect (OSTI)

    Crawford, B.E.; Roberson, N.R. [Duke University, Durham, North Carolina 27708 and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 (United States)] [Duke University, Durham, North Carolina 27708 and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 (United States); Bowman, J.D.; Knudson, J.N.; Penttilae, S.I.; Seestrom, S.J.; Yuan, V.W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Delheij, P.P. [TRIUMF, Vancouver, British Columbia, V6T 2A3 (CANADA)] [TRIUMF, Vancouver, British Columbia, V6T 2A3 (CANADA); Haseyama, T.; Masaike, A.; Matsuda, Y. [Physics Department, Kyoto University, Kyoto 606-01 (Japan)] [Physics Department, Kyoto University, Kyoto 606-01 (Japan); Lowie, L.Y.; Mitchell, G.E.; Stephenson, S.L. [North Carolina State University, Raleigh, North Carolina 27695-8202 and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 (United States)] [North Carolina State University, Raleigh, North Carolina 27695-8202 and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 (United States); Postma, H. [Delft University of Technology, Delft, 2629 JB (The Netherlands)] [Delft University of Technology, Delft, 2629 JB (The Netherlands); Sharapov, E.I. [Joint Institute for Nuclear Research, 141980 Dubna (Russia)] [Joint Institute for Nuclear Research, 141980 Dubna (Russia)

    1999-11-01

    Parity nonconservation (PNC) has been studied in the neutron {ital p}-wave resonances of {sup 106}Pd and {sup 108}Pd in the energy range of 20 to 2000 eV. Longitudinal asymmetries in {ital p}-wave capture cross sections are measured using longitudinally polarized neutrons incident on {approximately}20-g metal-powder targets at LANSCE. A CsI {gamma}-ray detector array measures capture cross section asymmetries as a function of neutron energy which is determined by the neutron time-of-flight method. A total of 21 {ital p}-wave resonances in {sup 106}Pd and 21 {ital p}-wave resonances in {sup 108}Pd were studied. One statistically significant PNC effect was observed in {sup 106}Pd, and no effects were observed in {sup 108}Pd. For {sup 106}Pd a weak spreading width of {Gamma}{sub w}=34{sub {minus}28}{sup +47}{times}10{sup {minus}7} eV was obtained. For {sup 108}Pd an upper limit on the weak spreading width of {Gamma}{sub w}{lt}12{times}10{sup {minus}7} eV was determined at the 68{percent} confidence level. {copyright} {ital 1999} {ital The American Physical Society}

  10. Effects of anode materials on resistive characteristics of NiO thin films

    SciTech Connect (OSTI)

    Jia, Ze; Wang, Linkai; Zhang, Naiwen; Ren, Tianling; Liou, Juin J.

    2013-01-28

    This letter shows that the NiO-based structure with different anodes has different resistive switching properties. A conical conductive filament (CF) model is proposed for oxygen vacancies distributed in NiO films. Modeling analysis reveals much larger dissolution velocity of CF near anodes than near cathodes during the reset process. Different interfaces shown in Auger electron spectroscopy can be bound with the model to reveal that CF is dissolved in the structure with Pt or Au as anodes, while CF remains constant if the anode material is Ti or Al, which can explain whether switching properties occur in the specific NiO-based structures.

  11. The catalytic behavior of precisely synthesized Pt–Pd bimetallic catalysts for use as diesel oxidation catalysts

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wong, Andrew P.; Kyriakidou, Eleni A.; Toops, Todd J.; Regalbuto, John R.

    2016-04-17

    The demands of stricter diesel engine emission regulations have created challenges for current exhaust systems. With advances in low-temperature internal combustion engines and their operations, advances must also be made in vehicle exhaust catalysts. Most current diesel oxidation catalysts use heavy amounts of precious group metals (PGMs) for hydrocarbon (HC), CO, and NO oxidation. These catalysts are expensive and are most often synthesized with poor bimetallic interaction and dispersion. In this paper, the goal was to study the effect of aging on diesel emission abatement of Pt–Pd bimetallic nanoparticles precisely prepared with different morphologies: well dispersed core–shell vs. well dispersedmore » homogeneously alloyed vs. poorly dispersed, poorly alloyed particles. Alumina and silica supports were studied. Particle morphology and dispersion were analyzed before and after hydrothermal treatments by XRD, EDX, and STEM. Reactivity as a function of aging was measured in simulated diesel engine exhaust. While carefully controlled bimetallic catalyst nanoparticle structure has a profound influence on initial or low temperature catalytic activity, the differences in behavior disappear with higher temperature aging as thermodynamic equilibrium is achieved. The metallic character of Pt-rich alumina-supported catalysts is such that behavior rather closely follows the Pt–Pd metal phase diagram. Nanoparticles disparately composed as well-dispersed core–shell (via seq-SEA), well-dispersed homogeneously alloyed (via co-SEA), and poorly dispersed, poorly alloyed (via co-DI) end up as well alloyed, large particles of almost the same size and activity. With Pd-rich systems, the oxidation of Pd also figures into the equilibrium, such that Pd-rich oxide phases appear in the high temperature forms along with alloyed metal cores. Finally, the small differences in activity after high temperature aging can be attributed to the synthesis methods, sequential SEA and co

  12. AcqGuide39pt1.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    PDF icon AcqGuide39pt1.doc&0; More Documents & Publications Chapter 39 - Acquisition of Information Technology AcqGuide38pt1.doc&0; Microsoft Word - AcqGuide16pt1...

  13. Microsoft Word - acqguide18pt0 March 2011 final | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    acqguide18pt0 March 2011 final Microsoft Word - acqguide18pt0 March 2011 final Microsoft Word - acqguide18pt0 March 2011 final More Documents & Publications Chapter 18 - Emergency...

  14. Oxygen Electroreduction on Nanoscale Pt/[TaOPO4/VC] and Pt/[Ta2O5...

    Office of Scientific and Technical Information (OSTI)

    Oxygen Electroreduction on Nanoscale PtTaOPO4VC and PtTa2O5VC in Alkaline Electrolyte Citation Details In-Document Search Title: Oxygen Electroreduction on Nanoscale Pt...

  15. Acqguide18pt0 March 2011 final | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Acquisitions PDF icon Acqguide18pt0 March 2011 final More Documents & Publications Chapter 18 - Emergency Acquisitions OPAM Policy Acquisition Guides Microsoft Word - acqguide18pt0...

  16. Pt3Re alloy nanoparticles as electrocatalysts for the oxygen...

    Office of Scientific and Technical Information (OSTI)

    Pt3Re alloy nanoparticles as electrocatalysts for the oxygen reduction reaction Citation ... on March 24, 2018 Title: Pt3Re alloy nanoparticles as electrocatalysts for the oxygen ...

  17. THE EFFECT OF CO ON HYDROGEN PERMEATION THROUGH PD AND INTERNALLY OXIDIZED AND UN-OXIDIZED PD ALLOY MEMBRANES

    SciTech Connect (OSTI)

    Shanahan, K.; Flanagan, T.; Wang, D.

    2010-10-20

    The H permeation of internally oxidized Pd alloy membranes such as Pd-Al and Pd-Fe, but not Pd-Y alloys, is shown to be more resistant to inhibition by CO(g) as compared to Pd or un-oxidized Pd alloy membranes. The increased resistance to CO is found to be greater at 423 K than at 473 K or 523 K. In these experiments CO was pre-adsorbed onto the membranes and then CO-free H{sub 2} was introduced to initiate the H permeation.

  18. Au-Pt heteroaggregate dendritic nanostructures and Au-Pt alloy nanoparticles and their use as catalysts

    DOE Patents [OSTI]

    Eichhorn, Bryan W.; Zhou, Shenghu; Jackson, Gregory Scott

    2011-10-18

    Au--Pt heteroaggregate dendritic nanostructures and AuPt alloy nanoparticles, and their use as anodic catalysts in fuel cells.

  19. An amorphous phase formation at palladium / silicon oxide (Pd...

    Office of Scientific and Technical Information (OSTI)

    An amorphous phase formation at palladium silicon oxide (PdSiOsub x) interface ... Title: An amorphous phase formation at palladium silicon oxide (PdSiOsub x) interface ...

  20. Synergistic Catalysis between Pd and Fe in Gas Phase Hydrodeoxygenatio...

    Office of Scientific and Technical Information (OSTI)

    Synergistic Catalysis between Pd and Fe in Gas Phase Hydrodeoxygenation of m-Cresol Citation Details In-Document Search Title: Synergistic Catalysis between Pd and Fe in Gas Phase ...

  1. Mode-selective chemistry on metal surfaces: The dissociative chemisorption of CH4 on Pt(111)

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Guo, Han; Jackson, Bret

    2016-05-13

    A quantum approach based on an expansion in vibrationally adiabatic eigenstates is used to explore CH4 dissociation on Pt(111). Computed sticking probabilities for molecules in the ground, 1v3 and 2v3, states are in very good agreement with the available experimental data, reproducing the variation in reactivity with collision energy and vibrational state. As was found in similar studies on Ni(100) and Ni(111), exciting the 1v1 symmetric stretch of CH4 is more effective at promoting the dissociative chemisorption of CH4 than exciting the 1v3 antisymmetric stretch. This behavior is explained in terms of symmetry, mode-softening, and nonadiabatic transitions between vibrationally adiabaticmore » states. We find that the efficacies of the bending modes for promoting reaction are reasonably large, and similar to the 1v3 state. The vibrational efficacies for promoting reaction on Ni(111) are larger than for reaction on Pt(111), due to the larger nonadiabatic couplings. As a result, our computed sticking probabilities are in good agreement with results from recent ab initio molecular dynamics and reactive force field studies.« less

  2. Examination of 80 deg. C desorption isotherms of tritium aged Pd/k and LANA.75

    SciTech Connect (OSTI)

    Staack, G. C.; Shanahan, K. L.; Walters, R. T.; Pilgrim, R. D.

    2008-07-15

    Metal hydrides, specifically Pd deposited on kieselguhr (Pd/k) and LaNi{sub 4.25}Al{sub 0.75} (LANA.75), have been used at the Savannah River Site for almost twenty years for hydrogen isotope separation and storage. Radiolytic decay of tritium to helium-3 in the metal matrix causes three classic changes in the performance of the hydride: the plateau pressure decreases, the plateau slope increases, and a heel forms, reducing the reversible capacity of the hydride. Deuterium and tritium isotherms were collected on the virgin materials, only tritium isotherms were collected at approximately 2 years, and both deuterium and tritium isotherms were collected at approximately 3.5 years of quiescent aging at 26 deg. C. Each sample was loaded to 0.5-0.6 T/M prior to each aging period. Points of interest include comparisons of each sample at different aging periods and isotope effects on aged hydride isotherms. Partial restoration of thermodynamic properties by sample cycling has been observed in LANA. 75, though not previously reported in Pd. The methods and results are presented. (authors)

  3. Spin current formation at the graphene/Pt interface for magnetization manipulation in magnetic nanodots

    SciTech Connect (OSTI)

    Shikin, A. M.; Rybkina, A. A.; Rybkin, A. G.; Klimovskikh, I. I.; Skirdkov, P. N.; Zvezdin, K. A.; Zvezdin, A. K.

    2014-07-28

    Spin electronic structure of the Graphene/Pt interface has been investigated. A large induced spin-orbit splitting (∼80 meV) of graphene π states with formation of non-degenerated Dirac-cone spin states at the K{sup ¯}-point of the Brillouin zone crossed with spin-polarized Pt 5d states at Fermi level was found. We show that this spin structure can be used as a spin current source in spintronic devices. By theoretical estimations and micromagnetic modeling based on the experimentally observed spin-orbit splitting, we demonstarte that the induced intrinsic magnetic field in such structure might be effectively used for induced remagnetization of the (Ni-Fe)-nanodots arranged atop the interface.

  4. Development of membranes for hydrogen separation: Pd-coated V-10Pd

    SciTech Connect (OSTI)

    Paglieri, Stephen N; Wermer, Joseph R; Buxbaum, Robert E; Ciocco, Michael V; Howard, Bret H; Morreale, Bryan D

    2009-01-01

    Numerous Group IVB and VB alloys were prepared and tested as potential membrane materials but most of these materials were brittle or exhibited cracking during hydrogen exposure. One of the more ductile alloys, V-10Pd (at. %), was fabricated into a thin (107-{micro}m thick) composite membrane coated with 100 nm of Pd on each side. The material was tested for hydrogen permeability, resistance to hydrogen embrittlement, and long term hydrogen flux stability. The hydrogen permeability, {phi}, of the V-10Pd membrane was 3.86 x 10{sup -8} mol H{sub 2} m{sup -1} s{sup -1} Pa{sup -0.5} (avg. of three different samples) at 400 C, which is slightly higher than the permeability of Pd-23Ag at that temperature. A 1400 h hydrogen flux test at 400 C demonstrated that the rate of metallic interdiffusion was slow between the V-10Pd foil and the 100-nm-thick Pd coating on the surface. However, at the end of testing the membrane cracked at 118 C because of hydrogen embrittlement.

  5. Ca{sub 2}Pd{sub 3}Ge, a new fully ordered ternary Laves phase structure

    SciTech Connect (OSTI)

    Doverbratt, Isa; Ponou, Simeon; Lidin, Sven

    2013-01-15

    The title compound, Ca{sub 2}Pd{sub 3}Ge, was prepared as a part of a systematic investigation of the Ca-Pd-Ge ternary phase diagram. The structure was determined and refined from single-crystal X-ray diffraction data. It is a new fully ordered ternary Laves phase with the space group R-3m, Z=3, a=5.6191 (5) A, c=12.1674 (7) A, wR{sub 2}=0.054 (all data) and is isostructural to Mg{sub 2}Ni{sub 3}Si (Noreus et al., 1985 [17]) but due to the larger size of all elements in Ca{sub 2}Pd{sub 3}Ge, the cell axes are approximately 10% longer. The compound may formally be considered as a Zintl compound, with [Pd{sub 3}Ge]{sup 4-} forming a poly-anionic network and divalent Ca cations located in truncated tetrahedral interstices. The electronic structure and chemical bonding of Ca{sub 2}Pd{sub 3}Ge is discussed in terms of LMTO band structure calculations and compared with CaPd{sub 2} (MgCu{sub 2}-type). - Graphical abstract: The title compound, Ca{sub 2}Pd{sub 3}Ge is a new fully ordered ternary Laves phase which may formally be considered as a Zintl compound, with [Pd{sub 3}Ge]{sup 4-} forming a poly-anionic network and divalent Ca cations located in truncated tetrahedral interstices. The structure is composed of Kagome net layers, consisting of Pd atoms only, which are stacked in an ABC sequence. Band structure calculations show that the Fermi level is located at a local minimum of the DOS (pseudo-gap) indicating that the charge is roughly optimized in the structure. Highlights: Black-Right-Pointing-Pointer Site specific segregation in a Laves phase that is also a Zintl phase. Black-Right-Pointing-Pointer Pseudo-gap at the Fermi level in a Laves phase. Black-Right-Pointing-Pointer Distorted Frank-Kasper polyhedron.

  6. PT-symmetric representations of fermionic algebras

    SciTech Connect (OSTI)

    Bender, Carl M.; Klevansky, S. P.

    2011-08-15

    A recent paper by Jones-Smith and Mathur, Phys. Rev. A 82, 042101 (2010) extends PT-symmetric quantum mechanics from bosonic systems (systems for which T{sup 2}=1) to fermionic systems (systems for which T{sup 2}=-1). The current paper shows how the formalism developed by Jones-Smith and Mathur can be used to construct PT-symmetric matrix representations for operator algebras of the form {eta}{sup 2}=0, {eta}{sup 2}=0, {eta}{eta}+{eta}{eta}={alpha}1, where {eta}={eta}{sup PT}=PT{eta}T{sup -1}P{sup -1}. It is easy to construct matrix representations for the Grassmann algebra ({alpha}=0). However, one can only construct matrix representations for the fermionic operator algebra ({alpha}{ne}0) if {alpha}=-1; a matrix representation does not exist for the conventional value {alpha}=1.

  7. AcqGuide70pt5.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AcqGuide70pt5.doc&#0; AcqGuide70pt5.doc&#0; AcqGuide70pt5.doc&#0; (16.21 KB) More Documents & Publications Chapter 70.3102-05-6: Contractor Compensation - Variable Pay Policy Flash 2016-34 AcqGuide41pt1.doc&#0;

  8. Fabrication of Pd/Pd-Alloy Films by Surfactant Induced Electroless Plating for Hydrogen Separation from Advanced Coal Gasification Processes

    SciTech Connect (OSTI)

    Ilias, Shamsuddin; Kumar, Dhananjay

    2012-07-31

    Dense Pd, Pd-Cu and Pd-Ag composite membranes on microporous stainless steel substrate (MPSS) were fabricated by a novel electroless plating (EP) process. In the conventional Pd-EP process, the oxidation-reduction reactions between Pd-complex and hydrazine result in an evolution of NH{sub 3} and N{sub 2} gas bubbles. When adhered to the substrate surface and in the pores, these gas bubbles hinder uniform Pd-film deposition which results in dendrite growth leading to poor film formation. This problem was addressed by introducing cationic surfactant in the electroless plating process known as surfactant induced electroless plating (SIEP). The unique features of this innovation provide control of Pd-deposition rate, and Pd-grain size distribution. The surfactant molecules play an important role in the EP process by tailoring grain size and the process of agglomeration by removing tiny gas bubbles through adsorption at the gas-liquid interface. As a result surfactant can tailor a nanocrystalline Pd, Cu and Ag deposition in the film resulting in reduced membrane film thickness. Also, it produces a uniform, agglomerated film structure. The Pd-Cu and Pd-Ag membranes on MPSS support were fabricated by sequential deposition using SIEP method. The pre- and post-annealing characterizations of these membranes (Pd, Pd-Cu and Pd-Ag on MPSS substrate) were carried out by SEM, EDX, XRD, and AFM studies. The SEM images show significant improvement of the membrane surface morphology, in terms of metal grain structures and grain agglomeration compared to the membranes fabricated by conventional EP process. The SEM images and helium gas-tightness studies indicate that dense and thinner films of Pd, Pd-Cu and Pd-Ag membranes can be produced with shorter deposition time using surfactant. H{sub 2} Flux through the membranes fabricated by SIEP shows large improvement compared to those by CEP with comparable permselectivity. Pd-MPSS composite membrane was subjected to test for long term

  9. Kinetics of monolayer graphene growth by segregation on Pd(111)

    SciTech Connect (OSTI)

    Mok, H. S.; Murata, Y.; Kodambaka, S., E-mail: kodambaka@ucla.edu [Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, California 90095 (United States); Ebnonnasir, A.; Ciobanu, C. V. [Department of Mechanical Engineering and Materials Science Program, Colorado School of Mines, Golden, Colorado 80401 (United States); Nie, S.; McCarty, K. F. [Sandia National Laboratories, Livermore, California 94550 (United States)

    2014-03-10

    Using in situ low-energy electron microscopy and density functional theory calculations, we follow the growth of monolayer graphene on Pd(111) via surface segregation of bulk-dissolved carbon. Upon lowering the substrate temperature, nucleation of graphene begins on graphene-free Pd surface and continues to occur during graphene growth. Measurements of graphene growth rates and Pd surface work functions establish that this continued nucleation is due to increasing C adatom concentration on the Pd surface with time. We attribute this anomalous phenomenon to a large barrier for attachment of C adatoms to graphene coupled with a strong binding of the non-graphitic C to the Pd surface.

  10. Transition metal nitride coated with atomic layers of Pt as a low-cost, highly stable electrocatalyst for the oxygen reduction reaction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tian, Xinlong; Adzic, Radoslav R.; Luo, Junming; Nan, Haoxiong; Zou, Haobin; Chen, Rong; Shu, Ting; Li, Xiuhua; Li, Yingwei; Song, Huiyi; et al

    2016-01-21

    Here, the main challenges to the commercial viability of polymer electrolyte membrane fuel cells are (i) the high cost associated with using large amounts of Pt in fuel cell cathodes to compensate for the sluggish kinetics of the oxygen reduction reaction, (ii) catalyst degradation, and (iii) carbon-support corrosion. To address these obstacles, our group has focused on robust, carbon-free transition metal nitride materials with low Pt content that exhibit tunable physical and catalytic properties. Here, we report on the high performance of a novel catalyst with low Pt content, prepared by placing several layers of Pt atoms on nanoparticles ofmore » titanium nickel binary nitride. For the ORR, the catalyst exhibited a more than 400% and 200% increase in mass activity and specific activity, respectively, compared with the commercial Pt/C catalyst. It also showed excellent stability/durability, experiencing only a slight performance loss after 10,000 potential cycles, while TEM results showed its structure had remained intact. The catalyst’s outstanding performance may have resulted from the ultrahigh dispersion of Pt (several atomic layers coated on the nitride nanoparticles), and the excellent stability/durability may have been due to the good stability of nitride and synergetic effects between ultrathin Pt layer and the robust TiNiN support.« less

  11. 102Pd(n, {gamma}) Cross Section Measurement Using DANCE

    SciTech Connect (OSTI)

    Hatarik, R.; Alpizar-Vicente, A. M. [Colorado School of Mines, Golden, CO 80401 (United States); Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bredeweg, T. A.; Esch, E.-I.; Haight, R. C.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Greife, U. [Colorado School of Mines, Golden, CO 80401 (United States)

    2006-03-13

    The neutron capture cross section of the proton rich nucleus 102Pd was measured with the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center. The target was a 2 mg Pd foil with 78% enriched 102Pd. It was held by a 0.9 {mu}m thick Mylar bag which was selected after comparing different thicknesses of Kapton and Mylar for their scattering background. To identify the contribution of the other Pd isotopes the data of a natural Pd sample was compared to the data of the 102Pd enriched sample. A 12C sample was used to determine the scattering background. The 102Pd(n, {gamma}) rate is of importance for the p-process nucleosynthesis.

  12. Seed influence on the ferromagnetic resonance response of Co/Ni multilayers

    SciTech Connect (OSTI)

    Sabino, Maria Patricia Rouelli, E-mail: maria-sabino@dsi.a-star.edu.sg; Tran, Michael; Hin Sim, Cheow; Ji Feng, Ying; Eason, Kwaku [Data Storage Institute, Agency for Science, Technology and Research, 5 Engineering Drive 1, Singapore 117608 (Singapore)

    2014-05-07

    The effect of Pd and Ru seed layers on the magnetic properties of [Co/Ni]{sub N} multilayers with varying number of bilayer repeats N is investigated using vector network analyzer ferromagnetic resonance. The effective anisotropy field H{sub Keff} is found to increase with N for Ru seed, but decreases for Pd until N?=?15. As N is increased beyond 15, H{sub Keff} decreases for both seeds. In contrast, the damping parameter ? decreases with N regardless of the seed, showing a 1/N dependence. Taking spin pumping into account, the intrinsic damping ?{sub 0} for both Pd and Ru seeds reduce to ?{sub 0} ? 0.01. These results demonstrate that there can be a strong influence of the seed/Co interface on anisotropy, especially for sufficiently low N, but not necessarily on ?{sub 0}.

  13. Temperature dependence of the Pd [ital K]-edge extended x-ray-absorption fine structure of PdC[sub [ital x

    SciTech Connect (OSTI)

    McCaulley, J.A. (Hoechst Celanese Research Division, Robert L. Mitchell Technical Center, 86 Morris Avenue, Summit, New Jersey 07901 (United States))

    1993-03-01

    Pd [ital K]-edge extended x-ray-absorption fine-structure (EXAFS) and x-ray-absorption near-edge-structure (XANES) measurements were performed on a Pd carbide phase, PdC[sub [ital x

  14. Blending Cr2O3 into a NiO-Ni electrocatalyst for sustained water splitting

    SciTech Connect (OSTI)

    Gong, Ming; Zhou, Wu; Kenney, Michael James; Kapusta, Rich; Cowley, Sam; Wu, Yingpeng; Lu, Bingan; Lin, Meng -Chang; Wang, Di -Yan; Yang, Jiang; Hwang, Bing -Joe; Dai, Hongjie

    2015-08-24

    The rising H2 economy demands active and durable electrocatalysts based on low-cost, earth-abundant materials for water electrolysis/photolysis. Here we report nanoscale Ni metal cores over-coated by a Cr2O3-blended NiO layer synthesized on metallic foam substrates. The Ni@NiO/Cr2O3 triphase material exhibits superior activity and stability similar to Pt for the hydrogen-evolution reaction in basic solutions. The chemically stable Cr2O3 is crucial for preventing oxidation of the Ni core, maintaining abundant NiO/Ni interfaces as catalytically active sites in the heterostructure and thus imparting high stability to the hydrogen-evolution catalyst. The highly active and stable electrocatalyst enables an alkaline electrolyzer operating at 20 mA cm2 at a voltage lower than 1.5 V, lasting longer than 3 weeks without decay. Thus, the non-precious metal catalysts afford a high efficiency of about 15 % for light-driven water splitting using GaAs solar cells.

  15. Are We There Yet? Pt-Alloy Catalysts

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Are we there yet? Pt-alloy catalysts Anu Kongkanand and Swami Kumaraguru General Motors Global Product Development, Fuel Cell Activities Present to the DOE DWG-CWG June 16, 2014 Thanks to Jingxin Zhang, Craig Gittleman, and Mark Mathias No! Outline * Catalyst long-term targets * Low PGM cathode * Pt surface area loss * Catalyst support 2 3 Long-term Catalyst Targets * Even at 10 g-Pt/veh, Pt demand/supply will shift, putting pressure on Pt price. * Need to cut Pt usage to the replacement level

  16. AcqGuide42pt3.doc | Department of Energy

    Office of Environmental Management (EM)

    1pt1.doc&#0; AcqGuide41pt1.doc&#0; AcqGuide41pt1.doc&#0; (13.23 KB) More Documents & Publications Chapter 41 - Acquisition of Utility Services Policy Flash 2016-31 Chapter 41: Utilities

    2pt3.doc&#0; AcqGuide42pt3.doc&#0; AcqGuide42pt3.doc&#0; (56.38 KB) More Documents & Publications Chapter 42 - Contract Administration Acquisition Guide Chapter 42.1202 - Novation Agreements Chapter 9.2: Performance Guarantees

  17. Overcoming Hydrocarbon Inhibition on Pd-based Diesel Oxidation Catalysts

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    with Rational Catalyst Design Approach | Department of Energy Overcoming Hydrocarbon Inhibition on Pd-based Diesel Oxidation Catalysts with Rational Catalyst Design Approach Overcoming Hydrocarbon Inhibition on Pd-based Diesel Oxidation Catalysts with Rational Catalyst Design Approach Discusses results of a project focused on overcoming hydrocarbon inhibition on Pd-based diesel oxidation catalysts by using a rational catalyst design approach. deer11_kapur.pdf (745.87 KB) More Documents &

  18. Efficient Pt catalysts for polymer electrolyte fuel cells

    SciTech Connect (OSTI)

    Fournier, J.; Gaubert, G.; Tilquin, J.Y.

    1996-12-31

    Commercialization of polymer electrolyte fuel cells (PEFCs) requires an important decrease in their production cost. Cost reduction for the electrodes principally concerns the decrease in the amount of Pt catalyst necessary for the functioning of the PEFC without affecting cell performance. The first PEFCs used in the Gemini Space Program had a loading of 4-10 mg pt/cm{sup 2}. The cost of the electrodes was drastically reduced when pure colloidal Pt was replaced by Pt supported on carbon (Pt/C) with a Pt content of 0.4 Mg/cm{sup 2}. Since the occurrence of that breakthrough, many studies have been aimed at further lowering the Pt loading. Today, the lowest loadings reported for oxygen reduction are of the order of 0.05 mg pt/cm{sup 2}. The carbon support of commercial catalysts is Vulcan XC-72 from Cabot, a carbon black with a specific area of 254 m{sup 2}/g. Graphites with specific areas ranging from 20 to 305 m{sup 2}/g are now available from Lonza. The first aim of the present study was to determine the catalytic properties for 02 reduction of Pt supported on these high specific area graphites. The second aim was to use Pt inclusion synthesis on these high area graphites, and to measure the catalytic performances of these materials. Lastly, this same Pt-inclusion synthesis was extended even for use with Vulcan and Black Pearls as substrates (two carbon blacks from Cabot). All these catalysts have been labelled Pt-included materials to distinguish them from the Pt-supported ones. It will be shown that the reduced Pt content Pt-included materials obtained with high specific area substrates a are excellent catalysts for oxygen reduction, especially at high currents. Therefore, Pt inclusion synthesis appears to be a new method to decrease the cathodic Pt loading.

  19. {sup 192}Pt: A piece in the Pt intruder state puzzle

    SciTech Connect (OSTI)

    McCutchan, E. A.

    2007-09-15

    A common interpretation of the light Pt isotopes involves the coexistence and mixing with proton intruder states from above the Z = 82 shell gap. An alternative description of the Pt isotopes using a simple, single configuration, the two-parameter interacting boson approximation model Hamiltonian, is discussed. To test these predictions, experiments on {sup 192}Pt were performed. New coincidence data found no support for several low-energy, low-spin states previously proposed in {beta} decay. Results from an ({alpha}, 2n) experiment identified states of the {gamma} band up to spin 9{sup +}. Results of these experiments are discussed in terms of IBA calculations.

  20. Monitoring Galvanic Replacement of Ag Nanoparticles by Pd using...

    Office of Scientific and Technical Information (OSTI)

    Conference: Monitoring Galvanic Replacement of Ag Nanoparticles by Pd using Low Dose In Situ Liquid STEM. Citation Details In-Document Search Title: Monitoring Galvanic ...

  1. Chemical and Morphological Evolution of Nanoporous Pd/Rh Alloy...

    Office of Scientific and Technical Information (OSTI)

    Conference: Chemical and Morphological Evolution of Nanoporous PdRh Alloy Particles for ... Country of Publication: United States Language: English Word Cloud More Like This Full ...

  2. Biography U. Dsterloh Degree: PD Dr.- Ing. habil. Institution...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    U. Dsterloh Degree: PD Dr.- Ing. habil. Institution: Clausthal University of Technology. Chair: chair for waste disposal technologies and geomechanics. 1982- 1988 field of study:...

  3. Supported bimetallic PdAu nanoparticles with superior electrocatalytic...

    Office of Scientific and Technical Information (OSTI)

    nanoparticles with superior electrocatalytic activity towards methanol oxidation Citation Details In-Document Search Title: Supported bimetallic PdAu nanoparticles with superior ...

  4. Neutron resonance spectroscopy of {sup 106}Pd and {sup 108}Pd from 20 to 2000 eV

    SciTech Connect (OSTI)

    Crawford, B.E.; Roberson, N.R. [Duke University, Durham, North Carolina 27708 and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 (United States)] [Duke University, Durham, North Carolina 27708 and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 (United States); Bowman, J.D.; Knudson, J.N.; Penttilae, S.I.; Seestrom, S.J.; Yuan, V.W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Delheij, P.P. [TRIUMF, Vancouver, British Columbia, V6T 2A3 (CANADA)] [TRIUMF, Vancouver, British Columbia, V6T 2A3 (CANADA); Haseyama, T.; Masaike, A.; Matsuda, Y. [Physics Department, Kyoto University, Kyoto 606-01 (Japan)] [Physics Department, Kyoto University, Kyoto 606-01 (Japan); Lowie, L.Y.; Mitchell, G.E.; Stephenson, S.L. [North Carolina State University, Raleigh, North Carolina 27695-8202 and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 (United States)] [North Carolina State University, Raleigh, North Carolina 27695-8202 and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 (United States); Postma, H. [University of Technology, Delft, 2600 GA (The Netherlands)] [University of Technology, Delft, 2600 GA (The Netherlands); Sharapov, E.I. [Joint Institute for Nuclear Research, 141980 Dubna (Russia)] [Joint Institute for Nuclear Research, 141980 Dubna (Russia)

    1998-08-01

    Parity nonconserving asymmetries have been measured in p-wave resonances of {sup 106}Pd and {sup 108}Pd. The data analysis requires knowledge of the neutron resonance parameters. Transmission and capture {gamma}-ray yields were measured for E{sub n}=20{endash}2000 eV with the time-of-flight method at the Los Alamos Neutron Science Center (LANSCE). A total of 28 resonances in {sup 106}Pd and 32 resonances in {sup 108}Pd were studied. The resonance parameters for {sup 106}Pd are new for all except one resonance. In {sup 108}Pd six new resonances were observed and the precision improved for many of the resonance parameters. A Bayesian analysis was used to assign orbital angular momentum for the resonances studied. {copyright} {ital 1998} {ital The American Physical Society}

  5. Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

    SciTech Connect (OSTI)

    Sengar, Saurabh K.; Mehta, B. R.; Govind

    2014-03-28

    In this report, X-ray photoelectron spectroscopy studies have been carried out on Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles having identical sizes corresponding to mobility equivalent diameters of 60, 40, and 20 nm. The nanoparticles were prepared by the gas phase synthesis method. The effect of size on valence and core levels in metal and alloy nanoparticles has been studied by comparing the values to those with the 60 nm nanoparticles. The effect of alloying has been investigated by comparing the valence and core level binding energies of Pd-Cu and Pd-Ag alloy nanoparticles with the corresponding values for Pd, Ag, and Cu nanoparticles of identical sizes. These effects have been explained in terms of size induced lattice contractions, alloying induced charge transfer, and hybridization effects. The observation of alloying and size induced binding energy shifts in bimetallic nanoparticles is important from the point of view of hydrogen reactivity.

  6. AcqGuide70pt31.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    PDF icon AcqGuide70pt31.doc&0; More Documents & Publications Microsoft Word - AcqGuide70pt31A.doc Policy Flash 2014-26 Acquisition Guide Chapter 70.31A - Costs...

  7. AcqGuide47pt1.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AcqGuide47pt1.doc&0; PDF icon AcqGuide47pt1.doc&0; More Documents & Publications Chapter 47 - Transportation TEC Working Group Topic Groups Manual Review Key Documents ...

  8. Characterization of Na+- beta-Zeolite Supported Pd and Pd Ag Bimetallic Catalysts using EXAFS, TEM and Flow Reactor

    SciTech Connect (OSTI)

    Huang,W.; Lobo, R.; Chen, J.

    2008-01-01

    Flow reactor studies of the selective hydrogenation of acetylene in the presence of ethylene have been performed on Na+ exchanged {beta}-zeolite supported Pd, Ag and PdAg catalysts, as an extension of our previous batch reactor studies [W. Huang, J.R. McCormick, R.F. Lobo, J.G. Chen, J. Catal. 246 (2007) 40-51]. Results from flow reactor studies show that the PdAg/Na+-{beta}-zeolite bimetallic catalyst has lower activity than Pd/Na+-{beta}-zeolite monometallic catalyst, while Ag/Na+-{beta}-zeolite does not show any activity for acetylene hydrogenation. However, the selectivity for the PdAg bimetallic catalyst is much higher than that for either the Pd catalyst or Ag catalyst. The selectivity to byproduct (ethane) is greatly inhibited on the PdAg bimetallic catalyst as well. The results from the current flow reactor studies confirmed the pervious results from batch reactor studies [W. Huang, J.R. McCormick, R.F. Lobo, J.G. Chen, J. Catal. 246 (2007) 40-51]. In addition, we used transmission electron microscope (TEM), extended X-ray absorption fine structure (EXAFS), and FTIR of CO adsorption to confirm the formation of Pd-Ag bimetallic alloy in the PdAg/Na+-{beta}-zeolite catalyst.

  9. Extended, Continuous Pt Nanostructures in Thick, Dispersed Electrodes

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Extended, Continuous Pt Nanostructures in Thick, Dispersed Electrodes This presentation does not contain any proprietary, confidential, or otherwise restricted information ...

  10. Microsoft Word - AcqGuide38pt Nov 2010 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AcqGuide38pt Nov 2010 Microsoft Word - AcqGuide38pt Nov 2010 PDF icon Microsoft Word - AcqGuide38pt Nov 2010 More Documents & Publications AcqGuide38pt1.doc&0; Microsoft Word - ...

  11. Atomic and electronic structure of Pd{sub 40}Ni{sub 40}P{sub...

    Office of Scientific and Technical Information (OSTI)

    (M) atoms and form a polar covalently bonded random network of P-M-P favoring certain angles. The remaining M atoms act as metallic glue with a tendency of nanoscale clustering of...

  12. Materials Data on NiGePd (SG:129) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  13. Materials Data on Ni(TePd)2 (SG:72) by Materials Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kristin Persson

    2015-02-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  14. Carbon-Supported IrNi Core-Shell Nanoparticles: Synthesis Characterization and Catalytic Activity

    SciTech Connect (OSTI)

    K Sasaki; K Kuttiyiel; L Barrio; D Su; A Frenkel; N Marinkovic; D Mahajan; R Adzic

    2011-12-31

    We synthesized carbon-supported IrNi core-shell nanoparticles by chemical reduction and subsequent thermal annealing in H{sub 2}, and verified the formation of Ir shells on IrNi solid solution alloy cores by various experimental methods. The EXAFS analysis is consistent with the model wherein the IrNi nanoparticles are composed of two-layer Ir shells and IrNi alloy cores. In situ XAS revealed that the Ir shells completely protect Ni atoms in the cores from oxidation or dissolution in an acid electrolyte under elevated potentials. The formation of Ir shell during annealing due to thermal segregation is monitored by time-resolved synchrotron XRD measurements, coupled with Rietveld refinement analyses. The H{sub 2} oxidation activity of the IrNi nanoparticles was found to be higher than that of a commercial Pt/C catalyst. This is predominantly due to Ni-core-induced Ir shell contraction that makes the surface less reactive for IrOH formation, and the resulting more metallic Ir surface becomes more active for H{sub 2} oxidation. This new class of core-shell nanoparticles appears promising for application as hydrogen anode fuel cell electrocatalysts.

  15. AcqGuide41pt1.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    1pt1.doc&#0; AcqGuide41pt1.doc&#0; AcqGuide41pt1.doc&#0; (13.23 KB) More Documents & Publications Chapter 41 - Acquisition of Utility Services Policy Flash 2016-31 Chapter 41: Utilities

  16. AcqGuide9pt2.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AcqGuide9pt2.doc&#0; AcqGuide9pt2.doc&#0; AcqGuide9pt2.doc&#0; (16.88 KB) More Documents & Publications Chapter 9.2: Performance Guarantees Policy Flash 2016-32 Chapter 9 - Contracting Qualifications

  17. AcqGuide3pt1.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    pt1.doc&0; AcqGuide3pt1.doc&0; PDF icon AcqGuide3pt1.doc&0; More Documents & Publications POLICY FLASH 2016-04 Procurement Integrity PI Brief 6 15 07 final2&0;

  18. Atomic force microscopy and x-ray photoelectron spectroscopy investigations of the morphology and chemistry of a PdCl{sub 2}/SnCl{sub 2} electroless plating catalysis system adsorbed onto shape memory alloy particles

    SciTech Connect (OSTI)

    Silvain, J.F.; Fouassier, O.; Lescaux, S.

    2004-11-01

    A study of the different stages of the electroless deposition of copper on micronic NiTi shape memory alloy particles activated by one-step and two-step methods has been conducted from both a chemical and a morphological point of view. The combination of x-ray photoelectron spectroscopy (XPS) measurements and atomic force microscopy (AFM) imaging has allowed detection of the distribution of the formed compounds and depth quantification and estimation of the surface topographic parameters. For the two-step method, at the sensitization of the early stages, it is observed by AFM that Sn is absorbed in form of clusters that tend to completely cover the surface and form a continuous film. XPS analysis have shown that Sn and Pd are first absorbed in form of oxide (SnO{sub 2} and PdO) and hydroxide [Sn(OH){sub 4}]. After the entire sensitization step, the NiTi substrate is covered with Sn-based compounds. After the sensitization and the activation steps the powder roughness increases. Behavior of the Sn and Pd growth for the one-step method does not follow the behavior found for the two-step method. Indeed, XPS analysis shows a three-dimensional (3D) growth of Pd clusters on top of a mixture of metallic tin, oxide (SnO) and hydroxide [Sn(OH){sub 2}]. These Pd clusters are covered with a thin layer of Pd-oxide contamination induced by the electroless process. The mean roughness for the one-step and two-step processes are equivalent. After copper deposition, the decrease of mean roughness is attributed to a filling of surface valleys, observed after the Sn-Pd coating step.

  19. Pt-Co/C Catalysts: PEMFC Performance and Durability

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Pt-Co/C Catalysts: PEMFC Performance and Durability Prasanna Mani, Harmeet Chhina, Emily Hopkins and Wendy Lee Slides presented by James Waldecker of Ford to the DOE Catalysis Working Group Meeting on June 16, 2014 Why are we looking at Pt-Co/C catalysts for PEM Fuel Cells even after so many years since the introduction? What trade offs in Pt-Co alloy characteristics can yield better performance and durability than Pt/C? - Pt:Co atomic ratio - Particle size - Metal loading What causes the

  20. Pd conductor for thick film hydrogen sensor

    SciTech Connect (OSTI)

    Felten, J.J.; Hoffheins, B.S.; Lauf, R.J.

    1996-12-31

    Cooperation between a materials developer and sensor designers has resulted in a palladium conductor used ro design and build a new hydrogen sensor that has superior performance characteristics and is also inexpensive to manufacture. Material characteristics give it faster response time and greater thermal/mechanical stability. The thick film palladium conductor paste, which can be fired at 850{degrees}C-950{degrees}C, has provided device designers a practical conductor paste with which to produce the improved sensor. The conductor uses a high surface area Pd powder combined with a binder glass that is chemically very inert, which combination produces a porous conductor that has good adhesion and chemical resistance. The current sensor design consists of three or four thick film Layers. Because of the flexibility of thick film techniques, the sensor element can be configured to any desired size and shape for specific instrument needs.

  1. High Throughput Combinatorial Screening of Biometic Metal-Organic...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Cu 2+ Ni Pd Pt SBU metal ions bare metal Carboxylate linkers Vibrational Spectroscopy of Hydrogen Raman *H 2 in gas phase is Raman active due to large polarizability ...

  2. Neutral bimetallic transition metal phenoxyiminato catalysts and related polymerization methods

    DOE Patents [OSTI]

    Marks, Tobin J.; Rodriguez, Brandon A.; Delferro, Massimiliano

    2012-08-07

    A catalyst composition comprising a neutral bimetallic diphenoxydiiminate complex of group 10 metals or Ni, Pd or Pt is disclosed. The compositions can be used for the preparation of homo- and co-polymers of olefinic monomer compounds.

  3. First-principles Study of Phenol Hydrogenation on Pt and Ni Catalysts...

    Office of Scientific and Technical Information (OSTI)

    Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy ...

  4. Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles

    SciTech Connect (OSTI)

    Maiti, A; Gee, R H; Maxwell, R; Saab, A

    2007-02-01

    Prompted by the need for a self-supported, chemically stable, and functionally flexible catalytic nanoparticle system, we explore a system involving Pd clusters coated with a monolayer of polyhedral oligomeric silsesquioxane (POSS) cages. With an initial theoretical focus on hydrogen catalysis and sequestration in the Pd-POSS system, we report Density Functional Theory (DFT) results on POSS binding energies to the Pd(110) surface, hydrogen storing ability of POSS, and possible pathways of hydrogen radicals from the catalyst surface to unsaturated bonds away from the surface.

  5. Electrical current suppression in Pd-doped vanadium pentoxide nanowires caused by reduction in PdO due to hydrogen exposure

    SciTech Connect (OSTI)

    Kim, Byung Hoon; Oh, Soon-Young; Yu, Han Young; Yun, Yong Ju; Kim, Yark Yeon; Hong, Won G.; Jeong, Hu Young; Lee, Jeong Yong; Kim, Hae Jin

    2010-04-19

    Pd nanoparticle-doped vanadium pentoxide nanowires (Pd-VONs) were synthesized. Electrical current suppression was observed when the Pd-VON was exposed to hydrogen gas, which cannot be explained by the work function changes mentioned in previous report such as Pd-doped carbon nanotubes and SnO{sub 2} nanowires. Using the x-ray photoelectron spectroscopy, we found that the reduction in PdO due to hydrogen exposure plays an important role in the current suppression of the Pd-VON.

  6. Kinetic effect of Pd additions on the hydrogen uptake of chemically activated, ultramicroporous carbon

    SciTech Connect (OSTI)

    Bhat, Vinay V; Contescu, Cristian I; Gallego, Nidia C

    2010-01-01

    The effect of mixing chemically-activated ultramicroporous carbon (UMC) with Pd nanopowder is investigated. Results show that Pd addition doubles the rate of hydrogen uptake, but does not enhance the hydrogen capacity or improve desorption kinetics. The effect of Pd on the rate of hydrogen adsorption supports the occurrence of the hydrogen spillover mechanism in the Pd - UMC system.

  7. Anomalous magnetic configuration of Mn{sub 2}NiAl ribbon and the role of hybridization in the martensitic transformation of Mn{sub 50}Ni{sub 50−x}Al{sub x} ribbons

    SciTech Connect (OSTI)

    Zhao, R. B.; Zhao, D. W.; Li, G. K.; Ma, L. E-mail: houdenglu@mail.hebtu.edu.cn; Zhen, C. M.; Hou, D. L. E-mail: houdenglu@mail.hebtu.edu.cn; Wang, W. H.; Liu, E. K.; Chen, J. L.; Wu, G. H.

    2014-12-08

    The magnetic configuration of Mn{sub 2}NiAl ribbon has been investigated. In contrast to Ni{sub 2}MnAl, the compound Mn{sub 2}NiAl with considerable disorder does exhibit ferromagnetism and, due to exchange interaction competition, both ferromagnetic and antiferromagnetic moment orientations can coexist between nearest neighbor Mn atoms. This is unexpected in Heusler alloys. Regarding the mechanism of the martensitic transformation in Mn{sub 50}Ni{sub 50−x}Al{sub x}, it is found that increasing the Al content results in an unusual change in the lattice constant, a decrease of the transformation entropy change, and enhancement of the calculated electron localization. These results indicate that the p-d covalent hybridization between Mn (or Ni) and Al atoms gradually increases at the expense of the d-d hybridization between Ni and Mn atoms. This leads to an increased stability of the austenite phase and a decrease of the martensitic transformation temperature. For 11 ≤ x ≤ 14, Mn{sub 50}Ni{sub 50−x}Al{sub x} ferromagnetic shape memory alloys are obtained.

  8. Overcoming Hydrocarbon Inhibition on Pd-based Diesel Oxidation...

    Broader source: Energy.gov (indexed) [DOE]

    Discusses results of a project focused on overcoming hydrocarbon inhibition on Pd-based diesel oxidation catalysts by using a rational catalyst design approach. deer11kapur.pdf ...

  9. Composite Pd and Pd Alloy Porous Stainless Steel Membranes for Hydrogen Production and Process Intensification

    SciTech Connect (OSTI)

    Yi Hua Ma; Nikolaos Kazantzis; Ivan Mardilovich; Federico Guazzone; Alexander Augustine; Reyyan Koc

    2011-11-06

    The synthesis of composite Pd membranes has been modified by the addition of a Al(OH){sub 3} graded layer and sequential annealing at high temperatures to obtain membranes with high permeance and outstanding selectivity stability for over 4000 hours at 450°C. Most of the membranes achieved in this work showed H{sub 2} flux well above 2010 DOE targets and in some case, also above 2015 DOE targets. Similar composite membranes were tested in water gas shift reaction atmospheres and showed to be stable with high CO conversion and high hydrogen recovery for over 1000 hours. The H{sub 2} permeance of composite Pd-Au membranes was studied as well as its resistance in H{sub 2}S containing atmospheres. H{sub 2}S poisoning of Pd-based membranes was reduced by the addition of Au and the loss undergone by membranes was found to be almost totally recoverable with 10-30 wt%Au. PSA technique was studied to test the possibility of H{sub 2}S and COS removal from feed stream with limited success since the removal of H{sub 2}S also led to the removal of a large fraction of the CO{sub 2}. The economics of a WGS bundle reactor, using the information of the membranes fabricated under this project and integrated into an IGCC plant were studied based on a 2D reactor modeling. The calculations showed that without a government incentive to impose a CO{sub 2} tax, application of WGS membrane reactors in IGCC would be not as economically attractive as regular pulverized coal plants.

  10. The PD-1/PD-L1 complex resembles the antigen-binding Fv domains of antibodies and T cell receptors

    SciTech Connect (OSTI)

    Lin, David Yin-wei; Tanaka, Yoshimasa; Iwasaki, Masashi; Gittis, Apostolos G.; Su, Hua-Poo; Mikami, Bunzo; Okazaki, Taku; Honjo, Tasuku; Minato, Nagahiro; Garboczi, David N. (NIH); (Kyoto)

    2008-07-29

    Signaling through the programmed death 1 (PD-1) inhibitory receptor upon binding its ligand, PD-L1, suppresses immune responses against autoantigens and tumors and plays an important role in the maintenance of peripheral immune tolerance. Release from PD-1 inhibitory signaling revives 'exhausted' virus-specific T cells in chronic viral infections. Here we present the crystal structure of murine PD-1 in complex with human PD-L1. PD-1 and PD-L1 interact through the conserved front and side of their Ig variable (IgV) domains, as do the IgV domains of antibodies and T cell receptors. This places the loops at the ends of the IgV domains on the same side of the PD-1/PD-L1 complex, forming a surface that is similar to the antigen-binding surface of antibodies and T cell receptors. Mapping conserved residues allowed the identification of residues that are important in forming the PD-1/PD-L1 interface. Based on the structure, we show that some reported loss-of-binding mutations involve the PD-1/PD-L1 interaction but that others compromise protein folding. The PD-1/PD-L1 interaction described here may be blocked by antibodies or by designed small-molecule drugs to lower inhibitory signaling that results in a stronger immune response. The immune receptor-like loops offer a new surface for further study and potentially the design of molecules that would affect PD-1/PD-L1 complex formation and thereby modulate the immune response.

  11. Cu--Pd--M hydrogen separation membranes

    DOE Patents [OSTI]

    Do{hacek over }an, Omer N; Gao, Michael C; Young, Rongxiang Hu; Tafen, De Nyago

    2013-12-17

    The disclosure provides an H2 separation membrane comprised of an allow having the composition Cu.Sub.(100-x-y)Pd.sub.xM.sub.y, where x is from about 35 to about 50 atomic percent and where y is from greater than 0 to about 20 atomic percent, and where M consists of magnesium, yttrium, aluminum, titanium, lanthanum, or combinations thereof. The M elements act as strong stabilizers for the B2 phase of the allow, and extend the critical temperature of the alloy for a given hydrogen concentration and pressure. Due to the phase stabilization and the greater temperature range over which a B2 phase can be maintained, the allow is well suited for service as a H2 separation membrane, particularly when applicable conditions are established or cycled above about 600.degree. C. over the course of expected operations. In certain embodiments, the B2 phase comprises at least 60 estimated volume percent of the allow at a steady-state temperature of 400.degree. C. The B2 phase stability is experimentally validated through HT-XRD.

  12. Temperature evolution of electromotive force from Pt on yttrium...

    Office of Scientific and Technical Information (OSTI)

    Temperature evolution of electromotive force from Pt on yttrium-iron-garnet under ferromagnetic resonance Citation Details In-Document Search Title: Temperature evolution of ...

  13. Jarzynski equality in PT-symmetric quantum mechanics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Deffner, Sebastian; Saxena, Avadh

    2015-04-13

    We show that the quantum Jarzynski equality generalizes to PT -symmetric quantum mechanics with unbroken PT -symmetry. In the regime of broken PT -symmetry the Jarzynski equality does not hold as also the CPT -norm is not preserved during the dynamics. These findings are illustrated for an experimentally relevant system – two coupled optical waveguides. It turns out that for these systems the phase transition between the regimes of unbroken and broken PT -symmetry is thermodynamically inhibited as the irreversible work diverges at the critical point.

  14. Scale-up Challenges of Novel Pt Catalysts

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Scale-up Challenges of Novel Pt Catalysts Catalysis Working Group Bryan Pivovar LANL January 21, 2015 This presentation does not contain any proprietary, confidential, or otherwise ...

  15. Engineering Multimetallic FePt-based nanowires for enhancing...

    Office of Scientific and Technical Information (OSTI)

    and methanol oxidation reactions Citation Details In-Document Search Title: Engineering Multimetallic FePt-based nanowires for enhancing oxygen reduction and methanol oxidation ...

  16. Local structure order in Pd??Cu?Si?? liquid

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yue, G. Q.; Iowa State Univ., Ames, IA; Zhang, Y.; Sun, Y.; Shen, B.; Dong, F.; Wang, Z. Y.; Zhang, R. J.; Zheng, Y. X.; Kramer, M. J.; et al

    2015-02-05

    The short-range order (SRO) in Pd??Cu?Si?? liquid was studied by high energy x-ray diffraction and ab initio molecular dynamics (MD) simulations. The calculated pair correlation functions at different temperatures agree well with the experimental results. The partial pair correlation functions from ab intio MD simulations indicate that Si atoms prefer to be uniformly distributed while Cu atoms tend to aggregate. By performing structure analysis using Honeycutt-Andersen index, Voronoi tessellation, and atomic cluster alignment method, we show that the icosahedron and face-centered cubic SRO increase upon cooling. The dominant SRO is the Pd-centered Pd?Si? motif, namely the structure of which motifmoreis similar to the structure of Pd-centered clusters in the Pd?Si? crystal. The study further confirms the existence of trigonal prism capped with three half-octahedra that is reported as a structural unit in Pd-based amorphous alloys. The majority of Cu-centered clusters are icosahedra, suggesting that the presence of Cu is benefit to promote the glass forming ability.less

  17. The Pd/Fe Interface in the Epitaxial System Pd/Fe/GaAs(001)- 4 x 6

    SciTech Connect (OSTI)

    Budnik, P.S.; Gordon, R.A.; Crozier, E.D.

    2007-01-18

    Magnetic properties of thin magnetic films are strongly affected by the nature of the interface between magnetic and non-magnetic layers. In spintronic devices the extent to which spins are scattered at an interface depends upon interfacial roughness, alloying, and impurities. We present a polarization-dependent XAFS study of a 1Pd/9Fe/GaAs(001)-(4 x 6) structure grown in situ in the MBE facility at the PNC/XOR, APS. To increase the interfacial roughness, the 1ML Pd was grown on the 9 ML Fe without first sputtering and annealing the Fe. An estimate of interfacial roughness, evidence for formation of Pd islands, their height, and the amount of As floating to the Pd surface from the GaAs are given.

  18. Airtricity Developments NI Ltd | Open Energy Information

    Open Energy Info (EERE)

    Airtricity Developments NI Ltd Jump to: navigation, search Name: Airtricity Developments NI Ltd Place: Belfast, Northern Ireland, United Kingdom Zip: BT2 7AF Sector: Wind energy...

  19. SF 6432-NI (04-95)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Retrieve latest version electronically. SF 6432-NI (061411) SECTION II STANDARD TERMS ... Control : SF 6432-NI Title: Standard Terms & Conditions for Fixed Price Contracts With ...

  20. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states atmore » the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.« less

  1. Magnetic order and heavy fermion behavior in CePd{sub 1+x}Al{sub 6-x}: Synthesis, structure, and physical properties

    SciTech Connect (OSTI)

    Tobash, Paul H., E-mail: ptobash@lanl.go [Materials Physics and Application Division, MPA-10, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States); Ronning, Filip; Thompson, J.D. [Materials Physics and Application Division, MPA-10, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bobev, Svilen [Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States); Bauer, Eric D. [Materials Physics and Application Division, MPA-10, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2010-03-15

    The physical properties including magnetic susceptibility, specific heat, and electrical resistivity of single crystals are reported for the compound CePd{sub 1+x}Al{sub 6-x} (x=0.5) which crystallizes in the tetragonal SrAu{sub 2}Ga{sub 5}-type structure (space group P4/mmm). The compound was grown from an excess of molten Al flux from the respective elements and the crystal structure was established from single-crystal X-ray diffraction. Anomalies in the low temperature specific heat C{sub p}(T) and electrical resistivity rho(T) show that the compound undergoes ferromagnetic order at T{sub C}=2.8 K. In the ordered state, CePd{sub 1.5}Al{sub 5.5} displays heavy fermion behavior with a Sommerfeld coefficient of ca. 500 mJ/mol-K{sup 2}. - Graphical abstract: The compound CePd{sub 1+x}Al{sub 6-x} (x=0.5) has been synthesized and structurally characterized by single-crystal X-ray diffraction. The measured physical properties of temperature and field dependent magnetic susceptibility, specific heat, and electrical resistivity suggests that the compound undergoes ferromagnetic order at ca. 2.8 K and further exhibits relatively heavy fermion behavior with a Sommerfeld coefficient of 500 mJ/mol-K2.

  2. Evidence for Low-Intensity D-D Reaction as a Result of Exothermic Deuterium Desorption from Au/Pd/PdO:D Heterostructure

    SciTech Connect (OSTI)

    Lipson, A.G.; Lyakhov, B.F.; Roussetski, A.S.; Akimoto, T.; Mizuno, T.; Asami, N.; Shimada, R.; Miyashita, S.; Takahashi, A.

    2000-09-15

    Low-intensity nuclear emissions (neutrons and charged particles) due to exothermic deuterium desorption from Au/Pd/PdO heterostructure loaded with deuterium by electrolysis have been studied by NE213 neutron detection as well as SSB and CR-39 charged-particle detectors in low-background conditions with large statistics. Similar measurements were performed with the Au/Pd/PdO:H heterostructure as a control. It has been established that in experiments with the Au/Pd/PdO:D system, the excessive 2.45-MeV neutrons and 3.0-MeV protons are better detected than with the Au/Pd/PdO:H system, where those detection rates for n and p did not exceed the cosmic background level. The levels of neutron and proton emissions for 40- to 60-{mu}m-thick samples are found to be close to one another and after subtracting background (Au/Pd/PdO:H count rate) consist of I{sub n} = (19 {+-} 2).10{sup -3} n/s and I{sub p} (4.0 {+-} 1.0).10{sup -3} p/s in a 4{pi} solid angle, respectively. These yields of D-D reaction products in Au/Pd/PdO heterostructure comply with the mean D-D reaction rate of {lambda}{sub dd} {approx} 10{sup -23}s{sup -1} per D-D pair.

  3. 7pt1AcquisitionPlanning.pdf | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    7pt1AcquisitionPlanning.pdf 7pt1AcquisitionPlanning.pdf (1.68 MB) More Documents & Publications ACQUISITION PLANNING Acquisition Planning--Extending A Management and Operating Contract Without Full and Open Competition; and Site and Utilization Management Planning Acquisitions___Communications.pdf

  4. 23pt0GreeningtheGovernment.pdf | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    3pt0GreeningtheGovernment.pdf 23pt0GreeningtheGovernment.pdf (1.69 MB) More Documents & Publications OCIO_Open_Government.pdf OfficeGovernmentEthicsGuidanceEthicsandProcurementIntegrity.pdf WC_1992_001__Class_WAIVER_OF_the_Governments_US_and_Fore.pdf

  5. Microsoft Word - AcqGuide42pt Nov 2010 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AcqGuide42pt Nov 2010 Microsoft Word - AcqGuide42pt Nov 2010 PDF icon Microsoft Word - AcqGuide42pt Nov 2010 More Documents & Publications Policy Flash 2015-11 Contractor Past...

  6. Microsoft Word - AcqGuide71pt1.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    1pt1.doc Microsoft Word - AcqGuide71pt1.doc PDF icon Microsoft Word - AcqGuide71pt1.doc More Documents & Publications Chapter 71 - Review and Approval of Contract and Financial ...

  7. Microsoft Word - AcqGuide7pt1.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    pt1.doc Microsoft Word - AcqGuide7pt1.doc ACQUISITION PLANNING PDF icon Microsoft Word - AcqGuide7pt1.doc More Documents & Publications ACQUISITION PLANNING Policy Flash 2015-13 ...

  8. Microsoft Word - AcqGuide70pt52Matrixpart2Redo | Department of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    pt52Matrixpart2Redo Microsoft Word - AcqGuide70pt52Matrixpart2Redo PDF icon Microsoft Word - AcqGuide70pt52Matrixpart2Redo More Documents & Publications Microsoft Word - ...

  9. Microsoft Word - AcqGuide16pt1 Nov 2010 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AcqGuide16pt1 Nov 2010 Microsoft Word - AcqGuide16pt1 Nov 2010 PDF icon Microsoft Word - AcqGuide16pt1 Nov 2010 More Documents & Publications OPAM Policy Acquisition Guides Chapter ...

  10. Microsoft Word - acqguide18pt0 Nov 2010 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    acqguide18pt0 Nov 2010 Microsoft Word - acqguide18pt0 Nov 2010 PDF icon Microsoft Word - acqguide18pt0 Nov 2010 More Documents & Publications OPAM Policy Acquisition Guides Chapter ...

  11. Anomalous Hall effect in YIG|Pt bilayers

    SciTech Connect (OSTI)

    Meyer, Sibylle Schlitz, Richard; Geprägs, Stephan; Opel, Matthias; Huebl, Hans; Goennenwein, Sebastian T. B.; Gross, Rudolf

    2015-03-30

    We measure the ordinary and the anomalous Hall effect in a set of yttrium iron garnet|platinum (YIG|Pt) bilayers via magnetization orientation dependent magnetoresistance experiments. Our data show that the presence of the ferrimagnetic insulator YIG leads to an anomalous Hall effect like voltage in Pt, which is sensitive to both Pt thickness and temperature. Interpretation of the experimental findings in terms of the spin Hall anomalous Hall effect indicates that the imaginary part of the spin mixing conductance G{sub i} plays a crucial role in YIG|Pt bilayers. In particular, our data suggest a sign change in G{sub i} between 10 K and 300 K. Additionally, we report a higher order Hall effect contribution, which appears in thin Pt films on YIG at low temperatures.

  12. Antiferromagnetic Kondo lattice in the layered compound CePd1-xBi₂ and

    Office of Scientific and Technical Information (OSTI)

    comparison to the superconductor LaPd1-xBi₂ (Journal Article) | SciTech Connect Antiferromagnetic Kondo lattice in the layered compound CePd1-xBi₂ and comparison to the superconductor LaPd1-xBi₂ Citation Details In-Document Search Title: Antiferromagnetic Kondo lattice in the layered compound CePd1-xBi₂ and comparison to the superconductor LaPd1-xBi₂ The layered compound CePd1-xBi₂ with the tetragonal ZrCuSi₂-type structure was obtained from excess Bi flux. Magnetic

  13. Method for making MgO buffer layers on rolled nickel or copper as superconductor substrates

    DOE Patents [OSTI]

    Paranthaman, Mariappan (Knoxville, TN); Goyal, Amit (Knoxville, TN); Kroeger, Donald M. (Knoxville, TN); List, III, Frederic A. (Andersonville, TN)

    2002-01-01

    Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

  14. MgO buffer layers on rolled nickel or copper as superconductor substrates

    DOE Patents [OSTI]

    Paranthaman, Mariappan (Knoxville, TN); Goyal, Amit (Knoxville, TN); Kroeger, Donald M. (Knoxville, TN); List, III, Frederic A. (Andersonville, TN)

    2001-01-01

    Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

  15. Surfactant-induced postsynthetic modulation of Pd nanoparticle crystallinity.

    SciTech Connect (OSTI)

    Liu, Y.; Wang, C.; Wei, Y.; Zhu, L.; Li, D.; Jiang, J. S.; Markovic, N. M.; Stamenkovic, V. R.; Sun, S.

    2011-02-01

    Modulation of Pd nanoparticle (NP) crystallinity is achieved by switching the surfactants of different binding strengths. Pd NPs synthesized in the presence of weak binding surfactants such as oleylamine possess polyhedral shapes and a polycrystalline nature. When oleylamine is substituted by trioctylphosphine, a much stronger binding surfactant, the particles become spherical and their crystallinity decreases significantly. Moreover, the Pd NPs reconvert their polycrystalline structure when the surfactant is switched back to oleylamine. Through control experiments and molecular dynamics simulation, we propose that this unusual nanocrystallinity transition induced by surfactant exchange was resulted from a counterbalance between the surfactant binding energy and the nanocrystal adhesive energy. The findings represent a novel postsynthetic approach to tailoring the structure and corresponding functional performance of nanomaterials.

  16. Pd/Cu Site Interchange and Non-Fermi-Liquid Behavior in UCu{sub 4}Pd

    SciTech Connect (OSTI)

    Booth, C.H.; MacLaughlin, D.E.; Heffner, R.H.; Kwei, G.H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); MacLaughlin, D.E. [Department of Physics, University of California, Riverside, California 92521 (United States)] [Department of Physics, University of California, Riverside, California 92521 (United States); Chau, R.; Maple, M.B. [Department of Physics, University of California, San Diego, California 92093 (United States)] [Department of Physics, University of California, San Diego, California 92093 (United States)

    1998-11-01

    X-ray-absorption fine-structure measurements of the local structure in UCu{sub 4}Pd are described which indicate a probable lattice-disorder origin for non-Fermi-liquid behavior in this material. Short Pd-Cu distances are observed, consistent with (24{plus_minus}3){percent} of the Pd atoms occupying nominally Cu sites. A {open_quotes}Kondo disorder{close_quotes} model, based on the effect on the local Kondo temperature T{sub K} of this interchange and some additional bond-length disorder, agrees quantitatively with previous experimental susceptibility data, and therefore also with specific heat and magnetic resonance experiments. {copyright} {ital 1998} {ital The American Physical Society }

  17. Inverse spin Hall effect in Pt/(Ga,Mn)As

    SciTech Connect (OSTI)

    Nakayama, H.; Chen, L.; Chang, H. W.; Ohno, H.; Matsukura, F.

    2015-06-01

    We investigate dc voltages under ferromagnetic resonance in a Pt/(Ga,Mn)As bilayer structure. A part of the observed dc voltage is shown to originate from the inverse spin Hall effect. The sign of the inverse spin Hall voltage is the same as that in Py/Pt bilayer structure, even though the stacking order of ferromagnetic and nonmagnetic layers is opposite to each other. The spin mixing conductance at the Pt/(Ga,Mn)As interface is determined to be of the order of 10{sup 19 }m{sup −2}, which is about ten times greater than that of (Ga,Mn)As/p-GaAs.

  18. Aqueous phase hydrodeoxygenation of polyols over Pd/WO3-ZrO2...

    Office of Scientific and Technical Information (OSTI)

    Aqueous phase hydrodeoxygenation of polyols over PdWO3-ZrO2: Role of Pd-WO3 interaction and hydrodeoxygenation pathway Citation Details In-Document Search This content will become ...

  19. Carbon-Supported bimetallic Pd-Fe catalysts for vapor-phasehydrodeoxy...

    Office of Scientific and Technical Information (OSTI)

    Carbon-Supported bimetallic Pd-Fe catalysts for vapor-phase hydrodeoxygenation of guaiacol Citation Details In-Document Search Title: Carbon-Supported bimetallic Pd-Fe catalysts ...

  20. Monolayer PtSe 2 , a New Semiconducting Transition-Metal-Dichalcogenide, Epitaxially Grown by Direct Selenization of Pt

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Yeliang; Li, Linfei; Yao, Wei; Song, Shiru; Sun, J. T.; Pan, Jinbo; Ren, Xiao; Li, Chen; Okunishi, Eiji; Wang, Yu-Qi; et al

    2015-05-21

    For single-layer transition-metal dichalcogenides (TMDs) receive significant attention due to their intriguing physical properties for both fundamental research and potential applications in electronics, optoelectronics, spintronics, catalysis, and so on. Here, we demonstrate the epitaxial growth of high-quality single-crystal, monolayer platinum diselenide (PtSe2), a new member of the layered TMDs family, by a single step of direct selenization of a Pt(111) substrate. We found that a combination of atomic-resolution experimental characterizations and first-principle theoretic calculations reveals the atomic structure of the monolayer PtSe2/Pt(111). Angle-resolved photoemission spectroscopy measurements confirm for the first time the semiconducting electronic structure of monolayer PtSe2 (in contrastmore » to its semimetallic bulk counterpart). The photocatalytic activity of monolayer PtSe2 film is evaluated by a methylene-blue photodegradation experiment, demonstrating its practical application as a promising photocatalyst. Moreover, circular polarization calculations predict that monolayer PtSe2 has also potential applications in valleytronics.« less

  1. {ital In situ} neutron-reflectometry measurements of hydrogen and deuterium absorption in a Pd/Nb/Pd layered film

    SciTech Connect (OSTI)

    Munter, A.E.; Heuser, B.J.; Ruckman, M.W.

    1997-06-01

    We present {ital in situ} neutron-reflectivity measurements of the hydrogen and deuterium absorption from the gas phase in a Pd/Nb/Pd thin film multilayer. Hydrogen and deuterium were both preferentially absorbed into the Nb layer at room temperature and at a pressure of 10 Torr. Genetic algorithm fits to the specular data indicate concentrations of approximately 0.71 [H]/[Nb] and 0.51 [D]/[Nb], placing the Nb well into the {beta} phase (or an {alpha}-like phase). {copyright} {ital 1997} {ital The American Physical Society}

  2. Selective Hydrogenation of Acetylene in the Presence of Ethylene on K+ -beta-Zeolite Supported Pd and PdAg Catalysts

    SciTech Connect (OSTI)

    Huang,W.; Pyrz, W.; Lobo, R.; Chen, J.

    2007-01-01

    The selective hydrogenation of acetylene in the presence of ethylene has been studied on K+ exchanged {beta}-zeolite supported Pd and PdAg catalysts. Results from batch reactor studies with Fourier transform infrared spectroscopy (FTIR) have shown that the K+-{beta}-zeolite support is more selective than the Al2O3 or Na+-{beta}-zeolite supports toward the hydrogenation of acetylene. The rate and equilibrium constants for Pd/K+-{beta}-zeolite and PdAg/K+-{beta}-zeolite were determined using a Langmuir-Hinshelwood model. The selectivity of the PdAg bimetallic catalyst is twice of that of the Pd catalyst. Results from flow reactor studies show that the PdAg/K+-{beta}-zeolite catalyst has higher selectivity but lower activity toward acetylene hydrogenation than the Pd/K+-{beta}-zeolite catalyst. The selectivity to the undesirable ethane by-product is inhibited on the bimetallic catalyst. Extended X-ray absorption fine structure (EXAFS) studies and transmission electron microscope (TEM) analysis confirm the formation of Pd-Ag bimetallic bonds in the PdAg/K+-{beta}-zeolite catalyst.

  3. Wall-catalyzed Water-Gas Shift Reaction in Multi-tubular, Pd and 80wt%Pd-20wt%Cu Membrane Reactors at 1173K

    SciTech Connect (OSTI)

    Osemwengie, I.; Enick, R.M.; Killmeyer, R.P.

    2007-07-20

    The high-temperature, water-gas shift reaction was conducted in 100 wt%Pd and 80 wt%Pd–20 wt%Cu (Pd80 wt%Cu) shell-and-tube membrane reactors at 1173 K with a 241 kPa (35 psig) trans-membrane pressure differential in the absence of heterogeneous catalyst particles. The tube bundle consisted of four parallel 15.25 cm long, 3.175 mm OD Pd-based tubes with a wall thickness of 125 μm. The modest catalytic activity of the Pd-based membrane surface for the forward WGSR, the high rate of hydrogen extraction through the Pd-based membranes, and the long residence times (1–5 s) resulted in a dramatic shift in carbon monoxide conversions of 93% at 1173 K and a 1.5:1 steam-to-carbon monoxide feed ratio—a value well above the equilibrium value of 54% associated with a conventional (non-membrane) reactor. Carbon monoxide conversions decreased from 93% to 66% and hydrogen recovery from 90% to 85% at a residence time of 5 s when the Pd was replaced with Pd80 wt%Cu, due to the lower permeance of the Pd80 wt%Cu alloy. SEM-EDS analysis of the membrane tubes suggested that the water-gas shift environment caused pinhole formation in the retentate surfaces of the Pd and Pd80 wt%Cu after approximately 8 days of operation.

  4. Hydrogen Absorption in Pd-based Nanostructures - Final Report

    SciTech Connect (OSTI)

    David Lederman

    2012-10-22

    Pd is known to absorb hydrogen. Molecules are normally chemisorbed at the surface in a process where the molecule breaks into two hydrogen atoms, and the protons are then absorbed into the bulk. This process consists of electron filling holes in the Pd 4d band near the Fermi energy, which due to the high density of states at the Fermi energy, is an energetically favorable process. Our aim with this project was to determine possible changes in magnetic properties with Pd nm-length-scale thick layers intercalated by magnetic materials. Before the start of this work, the literature indicated that there were several possible scenarios by which this could happen: i) the Pd will be magnetized due to a proximity effect with nearby magnetic layers, resulting in changes in the magnetization due to H2 absorption; ii) some H will be absorbed into the magnetic layers, causing a change in the magnetic exchange interactions; or iii) absorption of H2 will cause an expansion of the lattice, resulting in a magnetoelastic effect which changes the magnetic properties.

  5. Influence of a platinum functional layer on a Ni-Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} anode for thin-film solid oxide fuel cells

    SciTech Connect (OSTI)

    Kang, Sungmin; Cha, Suk Won E-mail: swcha@snu.ac.kr; Chang, Ikwhang; Kim, Young-Beom E-mail: swcha@snu.ac.kr

    2015-09-15

    A Pt functional layer was deposited between a Ni-Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (50 wt. % Ni) anode and an 8 mol. % yttria-stabilized zirconia electrolyte in order to enhance the performance of a thin film solid oxide fuel cell. By inserting this ultrathin functional layer, the ohmic impedance of the single cell was significantly reduced, and the maximum power density was increased by a factor of ∼1.55. However, excessive deposition of the Pt functional layer caused ionic conduction pathway blocking between the yttria-stabilized zirconia and Ni-Gd{sub 0.1}Ce{sub 0.9}O{sub 1.95} (Ni-GDC), deactivating the Ni-GDC as a mixed ionic and electronic conducting anode. As a result, both the ohmic impedance and anodic faradaic impedance were increased after introduction of excessive Pt functional layer, and the maximum power density was also reduced.

  6. Electrical oscillation in Pt/VO{sub 2} bilayer strips

    SciTech Connect (OSTI)

    Wang, Ying; Qi, Long; Xu, Yanjun; Wu, Yihong; Chai, Jianwei; Wang, Shijie; Yang, Yumeng; Tanaka, Hidekazu

    2015-02-14

    We report on the observation of stable electrical oscillation in Pt/vanadium dioxide (VO{sub 2}) bilayer strips, in which the Pt overlayer serves the dual purposes of heating up the VO{sub 2} and weakening the electric field in the VO{sub 2} layer. Systematic measurements in an ultrahigh vacuum nanoprobe system show that the oscillation frequency increases with the bias current and/or with decreasing device dimension. In contrast to most VO{sub 2}-based oscillators reported to date, which are electrically triggered, current-induced Joule heating in the Pt overlayer is found to play a dominant role in the generation of oscillation in Pt/VO{sub 2} bilayers. A simple model involving thermally triggered transition of VO{sub 2} on a heat sink is able to account for the experimental observations. The results in this work provide an alternative view of the triggering mechanism in VO{sub 2}-based oscillators.

  7. CRAD, NNSA- Packaging and Transportation (P&T)

    Office of Energy Efficiency and Renewable Energy (EERE)

    CRAD for Packaging and Transportation (P&T). Criteria Review and Approach Documents (CRADs) that can be used to conduct a well-organized and thorough assessment of elements of safety and health programs.

  8. Strain relief and Pd island shape evolution on the palladium and palladium hydride (100) surface

    SciTech Connect (OSTI)

    Kolesnikov, S. V.; Klavsyuk, A. L.; Saletsky, A. M. [Moscow State University (Russian Federation)

    2012-06-15

    The mesoscopic relaxation of small Pd islands on Pd(100) and PdH(100) surfaces is investigated on the atomic scale by performing molecular statics calculations. A strong strain and stress inhomogeneity in islands and topmost layers of the substrate is revealed. An unusual size dependence of the shape of islands is discovered.

  9. Microsoft Word - AcqGuide70pt31A.doc | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AcqGuide70pt31A.doc Microsoft Word - AcqGuide70pt31A.doc PDF icon Microsoft Word - AcqGuide70pt31A.doc More Documents & Publications AcqGuide70pt31.doc&0; Policy Flash 2014-26...

  10. Extended, Continuous Pt Nanostructures in Thick, Dispersed Electrodes |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Extended, Continuous Pt Nanostructures in Thick, Dispersed Electrodes Extended, Continuous Pt Nanostructures in Thick, Dispersed Electrodes Presented at the Department of Energy Fuel Cell Projects Kickoff Meeting, September 1 - October 1, 2009 pivovar_nrel_kickoff.pdf (1.9 MB) More Documents & Publications DOE's Fuel Cell Catalyst R&D Activities Fuel Cell Projects Kickoff Meeting PEMFC R&D at the DOE Fuel Cell Technologies Program

  11. Development of Novel Non Pt Group Metal Electrocatalysts for Proton

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Exchange Membrane Fuel Cell Applications | Department of Energy Novel Non Pt Group Metal Electrocatalysts for Proton Exchange Membrane Fuel Cell Applications Development of Novel Non Pt Group Metal Electrocatalysts for Proton Exchange Membrane Fuel Cell Applications These slides were presented at the 2010 New Fuel Cell Projects Meeting on September 28, 2010. 6_northeastern_mukerjee.pdf (5.24 MB) More Documents & Publications Science Magazine Highlight: Moving Towards Near Zero Platinum

  12. Radiosonde observations at Pt. Reyes and cloud properties retrieved from

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    GOES-WEST Radiosonde observations at Pt. Reyes and cloud properties retrieved from GOES-WEST Inoue, Toshiro MRI/JMA Category: Field Campaigns Low-level cloud formed off the west coast of continents plays an important role in general circulation and climate. Marine Stratus Radiation Aerosol and Drizzle (MASRAD) was conducted at the ARM mobile site deployed at Pt Reyes, California during April to September. Here, we studied the relationship between meteorological parameters observed by GPS

  13. Interfacial oxygen migration and its effect on the magnetic anisotropy in Pt/Co/MgO/Pt films

    SciTech Connect (OSTI)

    Chen, Xi; Feng, Chun E-mail: ghyu@mater.ustb.edu.cn; Liu, Yang; Jiang, Shaolong; Hua Li, Ming; Hua Yu, Guang E-mail: ghyu@mater.ustb.edu.cn; Long Wu, Zheng; Yang, Feng

    2014-02-03

    This paper reports the interfacial oxygen migration effect and its induced magnetic anisotropy evolution in Pt/Co/MgO/Pt films. During depositing the MgO layer, oxygen atoms from the MgO combine with the neighboring Co atoms, leading to the formation of CoO at the Co/MgO interface. Meanwhile, the films show in-plane magnetic anisotropy (IMA). After annealing, most of the oxygen atoms in CoO migrate back to the MgO layer, resulting in obvious improvement of Co/MgO interface and the enhancement of effective Co-O orbital hybridization. These favor the evolution of magnetic anisotropy from IMA to perpendicular magnetic anisotropy (PMA). The oxygen migration effect is achieved by the redox reaction at the Co/MgO interface. On the contrary, the transfer from IMA to PMA cannot be observed in Pt/Co/Pt films due to the lack of interfacial oxygen migration.

  14. Underpotential deposition of Ag adlayers on Pt(111): Structures and determination of O{sub 2} adsorption on Pt(111)

    SciTech Connect (OSTI)

    Marinkovic, N.S.; Wang, J.X.; Adzic, R.R.

    1997-09-01

    The structure of Ag adlayers deposited at underpotentials in sulfuric acid on Pt(111), and the inhibition of O{sub 2} reduction they cause, have been studied using grazing incident angle x-ray diffraction measurements, as well as linear sweep voltammetry and in situ FTIR spectroscopy. Ag forms a hexagonal incommensurate bilayer, with two mutually commensurate monolayers. It is aligned with the Pt(111) substrate, although slightly expanded. The first monolayer has a commensurate (1 x 1) structure. A second layer causes a restructuring of the first monolayer. Deposition of each monolayer is associated with one voltammetry Peak. A complete inhibition of O{sub 2} reduction on Pt(111) has been observed upon deposition of both, Ag monolayer and bilayer. Analysis of the inhibition of O{sub 2} reduction as a function of the Ag coverage shows that during reduction O{sub 2} adsorbs in a bridge configuration on Pt(111).

  15. Ethanol Oxidation on the Ternary PtRhSnO2/C Electrocatalysts with Varied Pt:Rh:Sn ratios

    SciTech Connect (OSTI)

    Adzic, R.R.; Li, M.; Kowal, A.; Sasaki, K.; Marinkovic, N.; Su, D.; Korach, E.; Liu, P.

    2010-05-30

    Ternary Pt-Rh-SnO{sub 2}/C electrocatalysts with the atomic ratio Pt:Rh:Sn = 3:1:x, where x varies from 2 to 6, were synthesized using the modified polyol method followed by thermal treatment. Several techniques used to characterize these electrocatalysts showed they were composed of homogeneous PtRh alloy and SnO{sub 2}, having all three constituents coexisting in single nanoparticles with the average particle size around 1.4 nm and a narrow size distribution. While all the electrocatalysts investigated exhibited high catalytic activity for ethanol oxidation, the most active one had the composition with the Pt:Rh:Sn = 3:1:4 atomic ratio. These ternary-electrocatalysts effectively split the C-C bond in ethanol at room temperature in acidic solutions, which is verified using the in situ IRRAS technique.

  16. Silicon ion irradiation effects on the magnetic properties of ion beam synthesized CoPt phase

    SciTech Connect (OSTI)

    Balaji, S.; Amirthapandian, S.; Panigrahi, B. K.; Mangamma, G.; Kalavathi, S.; Gupta, Ajay; Nair, K. G. M.

    2012-06-05

    Ion beam mixing of Pt/Co bilayers using self ion (Pt{sup +}) beam results in formation of CoPt phase. Upon ion beam annealing the ion mixed samples using 4 MeV Si{sup +} ions at 300 deg. C, diffusion of Co towards the Pt/Co interface is observed. The Si{sup +} ion beam rotates the magnetization of the CoPt phase from in plane to out of plane of the film.

  17. Steam reforming of fast pyrolysis-derived aqueous phase oxygenates over Co, Ni, and Rh metals supported on MgAl2O4

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Xing, Rong; Dagle, Vanessa Lebarbier; Flake, Matthew; Kovarik, Libor; Albrecht, Karl O.; Deshmane, Chinmay; Dagle, Robert A.

    2016-02-03

    In this paper we examine the feasibility of steam reforming the mixed oxygenate aqueous fraction derived from fast pyrolysis bio-oils. Catalysts selective towards hydrogen formation and resistant to carbon formation utilizing feeds with relatively low steam-to-carbon (S/C) ratios are desired. Rh (5 wt%), Pt (5 wt%), Ru (5 wt%), Ir (5 wt%), Ni (15 wt%), and Co (15 wt%) metals supported on MgAl2O4 were evaluated for catalytic performance at 500 °C and 1 atm using a complex feed mixture comprising acids, polyols, cycloalkanes, and phenolic compounds. The Rh catalyst was found to be the most active and resistant to carbonmore » formation. The Ni and Co catalysts were found to be more active than the other noble metal catalysts investigated (Pt, Ru, and Ir).« less

  18. Sulfur Tolerant Pd/Cu and Pd/Au Alloy Membranes for H2 Separation with High Pressure CO2 for Sequestration

    SciTech Connect (OSTI)

    Yi Hua Ma; Natalie Pomerantz; Chao-Huang Chen

    2008-09-30

    The effect of H{sub 2}S poisoning on Pd, Pd/Cu, and Pd/Au alloy composite membranes prepared by the electroless deposition method on porous Inconel supports was investigated to provide a fundamental understanding of the durability and preparation of sulfur tolerant membranes. X-ray photoelectron spectroscopy (XPS) studies showed that the exposure of pure Pd to 50 ppm H{sub 2}S/H{sub 2} mixtures caused bulk sulfide formation at lower temperatures and surface sulfide formation at higher temperatures. Lower temperatures, longer exposure times, and higher H{sub 2}S concentrations resulted in a higher degree of sulfidation. In a Pd membrane, the bulk sulfide formation caused a drastic irrecoverable H{sub 2} permeance decline and an irreparable loss in selectivity. Pd/Cu and Pd/Au alloy membranes exhibited permeance declines due to surface sulfide formation upon exposure to 50 ppm H{sub 2}S/H{sub 2} gas mixtures. However in contrast to the pure Pd membrane, the permeances of the Pd/Cu and Pd/Au alloy membranes were mostly recovered in pure H{sub 2} and the selectivity of the Pd alloy layers remained essentially intact throughout the characterization in H{sub 2}, He and H{sub 2}S/H{sub 2} mixtures which lasted several thousand hours. The amount of irreversible sulfur poisoning decreased with increasing temperature due to the exothermicity of H{sub 2}S adsorption. Longer exposure times increased the amount of irreversible poisoning of the Pd/Cu membrane but not the Pd/Au membrane. Pd/Au coupon studies of the galvanic displacement method showed that higher Au{sup 3+} concentrations, lower pH values, higher bath temperatures and stirring the bath at a rate of 200 rpm yielded faster displacement rates, more uniform depositions, and a higher Au content within the layers. While 400 C was found to be sufficient to form a Pd/Au alloy on the surface, high temperature X-ray diffraction (HTXRD) studies showed that even after annealing between 500-600 C, the Pd/Cu alloys could have

  19. Pd-vacancy complex in Ge: TDPAC and ab initio study

    SciTech Connect (OSTI)

    Abiona, Adurafimihan A.; Kemp, Williams; Timmers, Heiko

    2014-02-21

    Low temperature metal-induced-crystallized germanium is a promising alternative for silicon in Complementary Metal-Oxide-Semiconductor (CMOS) technology. Palladium (Pd) is one of the metals suitable for inducing the low temperature crystallization. It is not certain, how residual Pd atoms are integrated into the Ge lattice. Therefore, time-different ?-? perturbed angular correlation (TDPAC) technique using the {sup 100}Pd(?{sup 100}Rh) nuclear probe has been applied to study the hyperfine interactions of this probe in single crystalline undoped Ge. A Pd-vacancy (Pd-V) complex with a unique interaction frequency of 8.4(2) Mrad/s has been identified. The Pd-V complex has been measured to have a maximum fraction after annealing at 350 C. Density functional theory calculations have confirmed that the Pd-V complex may have the split-vacancy configuration in Ge, in contrast to the full-vacancy configuration observed in Si.

  20. Electrodeposition of Pd Nanowires and Nanorods on Carbon Nanoparticles

    SciTech Connect (OSTI)

    Bliznakov, S.; Vukmirovic, M.; Sutter, E.; Adzic, R.

    2011-06-01

    We report on the method for synthesizing palladium nanowires and nanorods involving the electrodeposition on oxidized amorphous carbon nanoparticles from chloride containing solutions. The effect of the deposition overpotential and the concentration of palladium ions on the morphology of the Pd electrodeposits have been established. Palladium grows predominately in the shape of nanowires if electrodeposited at potentials in the H underpotential deposition potential (UPD) range, where chloride ions are adsorbed only at the edges of nucleated monolayer-thick clusters on the carbon surface. The effect of the concentration of palladium ions on deposits morphology is also discussed. The mechanism of electrodeposition of Pd nanowires and nanorods in the H UPD potential range has been proposed.

  1. Partial encapsulation of Pd particles by reduced ceria-zirconia

    SciTech Connect (OSTI)

    Sun, H P.; Pan, X Q.; Graham, George W.; Jen, H. W.; McCabe, Robert W.; Thevuthasan, Suntharampillai; Peden, Charles HF.

    2005-11-14

    The interaction between metal particles and their oxide support can be strong so as to affect the reactivity of a catalyst system by, for example, encapsulation of the particles by the oxide. Direct observation of metal-oxide interfaces with atomic resolution is a challenge and can only be achieved by cross sectional high-resolution transmission electron microscopy (HRTEM). With this approach, we found partial encapsulation of Pd particles by reduced ceria-zirconia in a model, single-crystal thin film auto catalyst, indicating a strong interaction between Pd and the oxide. Besides obtaining HRTEM images, the valence of cerium was determined by electron energy loss spectroscopy (EELS). The effect of reduction and oxidation conditions on this interaction provides a qualitative explanation for a previously observed reversible reactivation of oxygen storage in model powder auto catalysts. The technique of cross sectional HRTEM can be applied to the study of other metal-particle-on-oxide systems.

  2. Density Functional Studies of Methanol Decomposition on Subnanometer Pd Clusters

    SciTech Connect (OSTI)

    Mehmood, Faisal; Greeley, Jeffrey P.; Curtiss, Larry A.

    2009-12-31

    A density functional theory study of the decomposition of methanol on subnanometer palladium clusters (primarily Pd4) is presented. Methanol dehydrogenation through C-H bond breaking to form hydroxymethyl (CH2OH) as the initial step, followed by steps involving formation of hydroxymethylene (CHOH), formyl (CHO), and carbon monoxide (CO), is found to be the most favorable reaction pathway. A competing dehydrogenation pathway with O-H bond breaking as the first step, followed by formation of methoxy (CH3O) and formaldehyde (CH2O), is slightly less favorable. In contrast, pathways involving C-O bond cleavage are much less energetically favorable, and no feasible pathways involving C-O bond formation to yield dimethyl ether (CH3OCH3) are found. Comparisons of the results are made with methanol decomposition products adsorbed on more extended Pd surfaces; all reaction intermediates are found to bind slightly more strongly to the clusters than to the surfaces.

  3. Computer simulation of D atoms in a Pd lattice

    SciTech Connect (OSTI)

    Berrondo, M. )

    1991-05-10

    We calculate the equilibrium configurations of a system of deuterium atoms absorbed in palladium. The interaction potential energy is taken as a sum of pair functionals including non-additive effects, which are crucial for this case. We conclude from our calculations that the most probable configuration for the deuterium in the {beta}-phase of PdD involves at least a partial occupation of the tetrahedral sites of the fcc palladium unit cell.

  4. ternay-pd-alloys-pall | netl.doe.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Designing and Validating Ternay Pd Alloys for Optimum Sulfur/Carbon Resistance Project No.: DE-FE0001181 Gas Permeation Cell and Test Stand Pall Corporation is developing an economically-viable hydrogen/carbon dioxide (H2/CO2) separation membrane system that would allow efficient capture of CO2 at high temperature and pressure from gasified coal in the presence of typical contaminants. Goals for the project include creating an advanced palladium alloy for optimum hydrogen separation performance

  5. Surface Structures of Cubo-octahedral Pt-Mo Catalyst Nanoparticles from Monte Carlo Simulations

    SciTech Connect (OSTI)

    Wang, Guofeng; Van Hove, M.A.; Ross, P.N.; Baskes, M.I.

    2005-03-31

    The surface structures of cubo-octahedral Pt-Mo nanoparticles have been investigated using the Monte Carlo method and modified embedded atom method potentials that we developed for Pt-Mo alloys. The cubo-octahedral Pt-Mo nanoparticles are constructed with disordered fcc configurations, with sizes from 2.5 to 5.0 nm, and with Pt concentrations from 60 to 90 at. percent. The equilibrium Pt-Mo nanoparticle configurations were generated through Monte Carlo simulations allowing both atomic displacements and element exchanges at 600 K. We predict that the Pt atoms weakly segregate to the surfaces of such nanoparticles. The Pt concentrations in the surface are calculated to be 5 to 14 at. percent higher than the Pt concentrations of the nanoparticles. Moreover, the Pt atoms preferentially segregate to the facet sites of the surface, while the Pt and Mo atoms tend to alternate along the edges and vertices of these nanoparticles. We found that decreasing the size or increasing the Pt concentration leads to higher Pt concentrations but fewer Pt-Mo pairs in the Pt-Mo nanoparticle surfaces.

  6. Crystallographic evidence for chemical ordering in UCu{sub 5{minus}x}Pd{sub x}

    SciTech Connect (OSTI)

    Chau, R.; Maple, M.B. [Department of Physics and the Institute for Pure and Applied Physical Sciences, University of California, San Diego, California 92093 (United States)] [Department of Physics and the Institute for Pure and Applied Physical Sciences, University of California, San Diego, California 92093 (United States); Robinson, R.A. [Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-07-01

    We report elastic neutron-diffraction measurements on UCu{sub 5{minus}x}Pd{sub x} (x=0.65, 1.0, and 1.5) using the High-Intensity Powder Diffractometer instrument at the Los Alamos Neutron Science Center. Data from six detector banks were simultaneously refined using Rietveld analysis. From the refinements of the data, we find that for Pd concentrations x{lt}1, Pd atoms preferentially occupy the minority Cu/Pd 4c sites, and Cu atoms fully occupy the majority Cu/Pd 16e sites. For Pd concentrations x{gt}1, Pd atoms fully occupy the minority sites and a mixture of Cu and Pd atoms occupy the 16e sites. At the special concentration x=1, we find that the Pd and Cu atoms occupy separate crystallographic sites. This arrangement of atoms is indicative of chemical ordering, although no superlattice peaks were observed. The implications of chemical ordering in UCu{sub 5{minus}x}Pd{sub x} on disorder-driven models of non-Fermi-liquid behavior will be discussed. {copyright} {ital 1998} {ital The American Physical Society}

  7. Thermally stable perpendicular magnetic anisotropy features of [Co/Pd]{sub m} multilayer matrix integrated with [CoO/Pd]{sub n} bottom layer

    SciTech Connect (OSTI)

    Lee, JaBin; An, GwangGuk; Yang, SeungMo; Hong, JinPyo; Chung, WooSeong

    2014-01-13

    We evaluated the perpendicular magnetic anisotropy (PMA) features of a hybrid [CoO/Pd]{sub 2}/[Co/Pd]{sub 7} multilayer (ML) matrix under annealing in which the [CoO/Pd]{sub 2} bottom layer was inserted. Annealing allowed for the diffusion of oxygen atoms existing in the inserted [CoO/Pd]{sub 2} layer, leading to an atomic structural reconfiguration event. The hybrid matrix was crucial to result in a higher effective anisotropy energy (3.40 Merg/cc) than an ordinary [Co/Pd]{sub 7} ML matrix (1.25 Merg/cc) under annealing at 450?C. X-ray photoelectron spectroscopy confirmed the presence of Co-O bonding states and annealing dependent oxygen atom diffusion. The possible nature of the enhanced PMA features is discussed.

  8. Equiatomic CoPt thin films with extremely high coercivity

    SciTech Connect (OSTI)

    Varghese, Binni; Piramanayagam, S. N. Yang, Yi; Kai Wong, Seng; Khume Tan, Hang; Kiat Lee, Wee; Okamoto, Iwao

    2014-05-07

    In this paper, magnetic and structural properties of near-equiatomic CoPt thin films, which exhibited a high coercivity in the film-normal directionsuitable for perpendicular magnetic recording media applicationsare reported. The films exhibited a larger coercivity of about 6.5 kOe at 8?nm. The coercivity showed a monotonous decrease as the film thickness was increased. The transmission electron microscopy images indicated that the as fabricated CoPt film generally consists of a stack of magnetically hard hexagonal-close-packed phase, followed by stacking faults and face-centred-cubic phase. The thickness dependent magnetic properties are explained on the basis of exchange-coupled composite media. Epitaxial growth on Ru layers is a possible factor leading to the unusual observation of magnetically hard hcp-phase at high concentrations of Pt.

  9. Interface Architecture Determined Electrocatalytic Activity of Pt on Vertically Oriented TiO2 Nanotubes

    SciTech Connect (OSTI)

    R Rettew; N Allam; F Alamgir

    2011-12-31

    The surface atomic structure and chemical state of Pt is consequential in a variety of surface-intensive devices. Herein we present the direct interrelationship between the growth scheme of Pt films, the resulting atomic and electronic structure of Pt species, and the consequent activity for methanol electro-oxidation in Pt/TiO{sub 2} nanotube hybrid electrodes. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements were performed to relate the observed electrocatalytic activity to the oxidation state and the atomic structure of the deposited Pt species. The atomic structure as well as the oxidation state of the deposited Pt was found to depend on the pretreatment of the TiO{sub 2} nanotube surfaces with electrodeposited Cu. Pt growth through Cu replacement increases Pt dispersion, and a separation of surface Pt atoms beyond a threshold distance from the TiO{sub 2} substrate renders them metallic, rather than cationic. The increased dispersion and the metallic character of Pt results in strongly enhanced electrocatalytic activity toward methanol oxidation. This study points to a general phenomenon whereby the growth scheme and the substrate-to-surface-Pt distance dictates the chemical state of the surface Pt atoms, and thereby, the performance of Pt-based surface-intensive devices.

  10. On phase equilibria and crystal structures in the systems Ce-Pd-B and Yb-Pd-B. Physical properties of R{sub 2}Pd{sub 13.6}B{sub 5} (R=Yb, Lu)

    SciTech Connect (OSTI)

    Sologub, Oksana; Rogl, Peter; Salamakha, Leonid; Bauer, Ernst; Hilscher, Gerfried; Michor, Herwig; Giester, Gerald

    2010-05-15

    Phase equilibria and crystal structures of ternary compounds were determined in the systems Ce-Pd-B and Yb-Pd-B at 850 deg. C in the concentration ranges up to 45 and 33 at% of Ce and Yb, respectively, employing X-ray single crystal and powder diffraction. Phase relations in the Ce-Pd-B system at 850 deg. C are governed by formation of extended homogeneity fields, tau{sub 2}-CePd{sub 8}B{sub 2-x} (0.10Pd{sub 25-x}B{sub 8-y} (1.06Pd{sub 3}B{sub x} (0Pd{sub 3}. Crystallographic parameters for the new structure type tau{sub 2}-CePd{sub 8}B{sub 2-x} (space group C2/c, a=1.78104(4) nm, b=1.03723(3) nm, c=1.16314(3), beta=118.515(1){sup o} for x=0.46) were established from X-ray single crystal diffraction. The crystal structures of tau{sub 2}-CePd{sub 8}B{sub 2-x} and tau{sub 3}-Ce{sub 3}Pd{sub 25-x}B{sub 3-y} are connected in a crystallographic group-subgroup relationship. Due to the lack of suitable single crystals, the novel structure of tau{sub 1}-Ce{sub 6}Pd{sub 47-x}B{sub 6} (x=0.2, C2/m space group, a=1.03594(2) nm, b=1.80782(3) nm, c=1.01997(2) nm, beta=108.321(1){sup o}) was determined from Rietveld refinement of X-ray powder diffraction data applying the structural model obtained from single crystals of homologous La{sub 6}Pd{sub 47-x}B{sub 6} (x=0.19) (X-ray single crystal diffraction, new structure type, space group C2/m, a=1.03988(2) nm, b=1.81941(5) nm, c=1.02418(2) nm, beta=108.168(1){sup o}). The Yb-Pd-B system is characterized by one ternary compound, tau{sub 1}-Yb{sub 2}Pd{sub 14}B{sub 5}, forming equilibria with extended solution YbPd{sub 3}B{sub x}, YbB{sub 6}, Pd{sub 5}B{sub 2} and Pd{sub 3}B. The crystal structures of both Yb{sub 2}Pd{sub 14}B{sub 5} and isotypic Lu{sub 2}Pd{sub 14}B{sub 5} were determined from X-ray Rietveld refinements and found to be closely related to the Y{sub 2}Pd{sub 14}B{sub 5}-type (I4{sub 1}/amd). The crystal structure of

  11. Magnetic instability of Kondo insulators

    SciTech Connect (OSTI)

    Wang, Ziqiang [Los Alamos National Lab., NM (United States)]|[Boston Univ., MA (United States). Dept. of Physics; Li, Xiao-Ping [Rutgers--the State Univ., Piscataway, NJ (United States). Serin Physics Lab.; Lee, Dung-Hai [International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center

    1993-09-01

    We review a number of experiments on isoelectronic, isostructural ternary compounds CeTSn (T=Ni,Pd,Sn) and alloys CeNi{sub 1-x}(Pd,Pt){sub x}Sn, and propose a finite temperature phase diagram describing the evolution of a Kondo insulator to an antiferromagnetic Kondo state with decreasing hybridization or Kondo coupling. We then provide microscopic justifications for the phase diagram by analyzing the magnetic properties of the symmetric Kondo lattice model in two dimensions.

  12. Phase Stability for the Pd-Si System. First-Principles, Experiments, and Solution-Based Modeling

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhou, S. H.; Huo, Y.; Napolitano, Ralph E.

    2015-11-05

    Relative stabilities of the compounds in the binary Pd-Si system were assessed using first-principles calculations and experimental methods. Calculations of lattice parameters and enthalpy of formation indicate that Pd5Si-μ, Pd9Si2-α, Pd3 Si-β, Pd2 Si-γ, and PdSi-δ are the stable phases at 0 K (-273 °C). X-ray diffraction analyses (XRD) and electron probe microanalysis (EPMA) of the as-solidified and heat-treated samples support the computational findings, except that the PdSi-δ phase was not observed at low temperature. Considering both experimental data and first-principles results, the compounds Pd 5 Si-μ, Pd9 Si2-α, Pd3Si-β, and Pd2Si-γ are treated as stable phases down to 0more » K (-273 °C), while the PdSi-δ is treated as being stable over a limited range, exhibiting a lower bound. Using these findings, a comprehensive solution-based thermodynamic model is formulated for the Pd-Si system, permitting phase diagram calculation. Moreover, the liquid phase is described using a three-species association model and other phases are treated as solid solutions, where a random substitutional model is adopted for Pd-fcc and Si-dia, and a two-sublattice model is employed for Pd5Si-μ, Pd9Si2-α, Pd3Si-β, Pd2Si-γ, and PdSi-δ. Model parameters are fitted using available experimental data and first-principles data, and the resulting phase diagram is reported over the full range of compositions.« less

  13. Oxygen-induced Y surface segregation in a CuPdY ternary alloy

    SciTech Connect (OSTI)

    Tafen, D. N.; Miller, J. B.; Dogan, O. N.; Baltrus, J. P.; Kondratyuk, P.

    2013-01-01

    We present a comprehensive theoretical and experimental study of the segregation behavior of the ternary alloy CuPdY in vacuum (i.e., the clean surface) and in the presence of oxygen. Theoretical prediction shows that for clean surface, yttrium will substitute first for Cu and then for Pd at the subsurface lattice site before segregating to the surface where it substitutes for Cu. XRD characterization of the surface of CuPdY indicates the presence of two major phases, B2 CuPd and Pd{sub 3}Y. In the presence of adsorbed oxygen, theory predicts that Y preferentially occupies surface sites due to its stronger oxygen affinity compared to Cu and Pd. XPS experiments confirm the computational results in the adsorbed oxygen case, showing that surface segregation of yttrium is induced by the formation of Y-oxides at the top-surface of the alloy.

  14. Improving the phase stability and oxidation resistance of B-NiAl

    SciTech Connect (OSTI)

    Brammer, Travis

    2011-08-15

    replacing Ni based superalloys. Modifications to NiAl were explored to increase the phase stability and oxidation resistance which would allow these alloys to be used at even higher temperatures yielding greater efficiencies. The extended Miedema model was an effective tool that screened all of the potential phase space for ternary substitutions to NiAl and found the few potential systems worth further investigation. After production of the alloys it was determined that Ir, Rh, and Pd were the top candidates for substitution on Ni site up to 12 at%. The melting temperature of NiAl could be increased as much as 150 C with 12 at% Ir and 130 C with 12 at% Rh substitution. Pall adium on the other hand decreased the melting temperature by 50 C at the 12 at% substitution level. The grain size was found to have a profound influence on the oxidation resistance. Both Ir and Rh substitutions resulted in finer grain sizes compared to Pd substitutions or base NiAl. The grain size increased drastically during high temperature annealing with the PGM substitutions hindering grain growth only slightly. However, the addition of 0.05 at% Hf limited the grain growth dramatically during high temperature annealing. NiAl inherently has respectable oxidation resistance up to 1100 C. It was found through experimental testing that both Ir and Rh substitutions improve the oxidation resistance of NiAl at ultra-high temperatures with Ir performing the best. Both PGM substitutions decreased the growth rate as well as forming a more adherent oxide scale. Pd substitutions appeared to have a negligible effect to the oxidation resistance of NiAl. Hafnium addition of 0.05 at% was found to decrease the oxidation rate as well as increase the scale adherence. The combination of both Ir substitution (6-9 at%) and Hf addition (0.05 at%) produced the alloy with the best oxidation resistance. Although improvements in phase stability and oxidation resistance have been made to the NiAl system, more development and

  15. Abnormal bipolar resistive switching behavior in a Pt/GaO{sub 1.3}/Pt structure

    SciTech Connect (OSTI)

    Guo, D. Y.; Wu, Z. P.; Zhang, L. J.; Yang, T.; Hu, Q. R.; Lei, M.; Tang, W. H. E-mail: pgli@zstu.edu.cn; Li, P. G. E-mail: pgli@zstu.edu.cn; Li, L. H.

    2015-07-20

    A stable and repeatable abnormal bipolar resistive switching behavior was observed in a Pt/GaO{sub 1.3}/Pt sandwich structure without an electroforming process. The low resistance state (LRS) and the high resistance state (HRS) of the device can be distinguished clearly and be switched reversibly under a train of the voltage pulses. The LRS exhibits a conduction of electron tunneling, while the HRS shows a conduction of Schottky-type. The observed phenomena are considered to be related to the migration of oxygen vacancies which changes the space charge region width of the metal/semiconductor interface and results in a different electron transport mechanism.

  16. Observation of inverse spin Hall effect in ferromagnetic FePt alloys using spin Seebeck effect

    SciTech Connect (OSTI)

    Seki, Takeshi Takanashi, Koki; Uchida, Ken-ichi; Kikkawa, Takashi; Qiu, Zhiyong; Saitoh, Eiji

    2015-08-31

    We experimentally observed the inverse spin Hall effect (ISHE) of ferromagnetic FePt alloys. Spin Seebeck effect due to the temperature gradient generated the spin current (J{sub s}) in the FePt|Y{sub 3}Fe{sub 5}O{sub 12} (YIG) structure, and J{sub s} was injected from YIG to FePt and converted to the charge current through ISHE of FePt. The significant difference in magnetization switching fields for FePt and YIG led to the clear separation of the voltage of ISHE from that of anomalous Nernst effect in FePt. We also investigated the effect of ordering of FePt crystal structure on the magnitude of ISHE voltage in FePt.

  17. Magnetic field effects on transport properties of PtSn4 (Journal...

    Office of Scientific and Technical Information (OSTI)

    field effects on transport properties of PtSn4 Prev Next Title: Magnetic field effects on transport properties of PtSn4 Authors: Mun, Eundeok ; Ko, Hyunjin ; Miller, Gordon ...

  18. Pressure-Induced Structural Phase Transition in CeNi: X-ray and Neutron Scattering Studies and First-Principles Calculations

    SciTech Connect (OSTI)

    Mirmelstein, A.; Podlesnyak, Andrey A.; dos Santos, Antonio M.; Ehlers, Georg; Kerbel, O.; Matvienko, V.; Sefat, A. S.; Saporov, B.; Halder, G. J.; Tobin, J. G.

    2015-08-03

    The pressure-induced structural phase transition in the intermediate-valence compound CeNi has been investigated by x-ray and neutron powder diffraction techniques. It is shown that the structure of the pressure-induced CeNi phase (phases) can be described in terms of the Pnma space group. Equations of state for CeNi on both sides of the phase transition are derived and an approximate P-T phase diagram is suggested for P<8 GPa and T<300 K. The observed Cmcm→Pnma structural transition is then analyzed using density functional theory calculations, which successfully reproduce the ground state volume, the phase transition pressure, and the volume collapse associated with the phase transition.

  19. Pressure-Induced Structural Phase Transition in CeNi: X-ray and Neutron Scattering Studies and First-Principles Calculations

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mirmelstein, A.; Podlesnyak, Andrey A.; dos Santos, Antonio M.; Ehlers, Georg; Kerbel, O.; Matvienko, V.; Sefat, A. S.; Saporov, B.; Halder, G. J.; Tobin, J. G.

    2015-08-03

    The pressure-induced structural phase transition in the intermediate-valence compound CeNi has been investigated by x-ray and neutron powder diffraction techniques. It is shown that the structure of the pressure-induced CeNi phase (phases) can be described in terms of the Pnma space group. Equations of state for CeNi on both sides of the phase transition are derived and an approximate P-T phase diagram is suggested for P<8 GPa and T<300 K. The observed Cmcm→Pnma structural transition is then analyzed using density functional theory calculations, which successfully reproduce the ground state volume, the phase transition pressure, and the volume collapse associated withmore » the phase transition.« less

  20. Hydrogenation of Acetylene-Ethylene Mixtures over Pd and Pd-Ag Alloys: First-Principles Based Kinetic Monte Carlo Simulations

    SciTech Connect (OSTI)

    Mei, Donghai; Neurock, Matthew; Smith, C Michael

    2009-10-22

    The kinetics for the selective hydrogenation of acetylene-ethylene mixtures over model Pd(111) and bimetallic Pd-Ag alloy surfaces were examined using first principles based kinetic Monte Carlo (KMC) simulations to elucidate the effects of alloying as well as process conditions (temperature and hydrogen partial pressure). The mechanisms that control the selective and unselective routes which included hydrogenation, dehydrogenation and C-?C bond breaking pathways were analyzed using first-principle density functional theory (DFT) calculations. The results were used to construct an intrinsic kinetic database that was used in a variable time step kinetic Monte Carlo simulation to follow the kinetics and the molecular transformations in the selective hydrogenation of acetylene-ethylene feeds over Pd and Pd-Ag surfaces. The lateral interactions between coadsorbates that occur through-surface and through-space were estimated using DFT-parameterized bond order conservation and van der Waal interaction models respectively. The simulation results show that the rate of acetylene hydrogenation as well as the ethylene selectivity increase with temperature over both the Pd(111) and the Pd-Ag/Pd(111) alloy surfaces. The selective hydrogenation of acetylene to ethylene proceeds via the formation of a vinyl intermediate. The unselective formation of ethane is the result of the over-hydrogenation of ethylene as well as over-hydrogenation of vinyl to form ethylidene. Ethylidene further hydrogenates to form ethane and dehydrogenates to form ethylidyne. While ethylidyne is not reactive, it can block adsorption sites which limit the availability of hydrogen on the surface and thus act to enhance the selectivity. Alloying Ag into the Pd surface decreases the overall rated but increases the ethylene selectivity significantly by promoting the selective hydrogenation of vinyl to ethylene and concomitantly suppressing the unselective path involving the hydrogenation of vinyl to ethylidene

  1. Fuel cycle integration issues associated with P/T technology

    SciTech Connect (OSTI)

    Michaels, G.E.; Ludwig, S.B.

    1992-04-01

    The three primary interfaces between a generic partitioning and transmutation (P/T) technology and the existing United States fuel cycle are the light-water reactor (LWR) spent fuel inventory, the reprocessed uranium (RU) stream, and the high-level waste stream. The features and implications of these three interfaces are reviewed and their implications for P/T system design and for waste management are assessed. The variability of transuranic nuclide composition in the LWR spent fuel is calculated and its potential implications for transmutation system core design are discussed. The radiological characteristics of the RU stream are presented, and options for disposition of the stream are reviewed. Most P/T scenarios assume that RU will be recycled to LWRs. This study demonstrates, however, that LWR recycle cannot totally consume the reprocessed stream, and disposal of a waste uranium steam with high levels of radiologically-significant isotopes will still be necessary. The radioactivity of the tails stream for enrichment plants resulting from a dedicated RU campaign is calculated. The tendency of gaseous diffusion plant enrichment technology to deplete the tails stream of minor uranium isotopes is seen as a benefit and an advantage over Atomic Vapor Laser Isotope Separation-type technology. Finally, the implications of P/T on LWR-origin wastes reporting to the repository is discussed, and several significant differences between LWR-origin waste originating from transmutation systems are assessed.

  2. Fuel cycle integration issues associated with P/T technology

    SciTech Connect (OSTI)

    Michaels, G.E.; Ludwig, S.B.

    1992-01-01

    The three primary interfaces between a generic partitioning and transmutation (P/T) technology and the existing United States fuel cycle are the light-water reactor (LWR) spent fuel inventory, the reprocessed uranium (RU) stream, and the high-level waste stream. The features and implications of these three interfaces are reviewed and their implications for P/T system design and for waste management are assessed. The variability of transuranic nuclide composition in the LWR spent fuel is calculated and its potential implications for transmutation system core design are discussed. The radiological characteristics of the RU stream are presented, and options for disposition of the stream are reviewed. Most P/T scenarios assume that RU will be recycled to LWRs. This study demonstrates, however, that LWR recycle cannot totally consume the reprocessed stream, and disposal of a waste uranium steam with high levels of radiologically-significant isotopes will still be necessary. The radioactivity of the tails stream for enrichment plants resulting from a dedicated RU campaign is calculated. The tendency of gaseous diffusion plant enrichment technology to deplete the tails stream of minor uranium isotopes is seen as a benefit and an advantage over Atomic Vapor Laser Isotope Separation-type technology. Finally, the implications of P/T on LWR-origin wastes reporting to the repository is discussed, and several significant differences between LWR-origin waste originating from transmutation systems are assessed.

  3. Annealing, lattice disorder and non-Fermi liquid behavior in UCu4Pd

    SciTech Connect (OSTI)

    Booth, C.H.; Scheidt, E.-W.; Killer, U.; Weber, A.; Kehrein, S.

    2002-07-30

    The magnetic and electronic properties of non-Fermi liquid UCu{sub 4Pd} depend on annealing conditions. Local structural changes due to this annealing are reported from UL{sub III}- and Pd K-edge x-ray absorption fine-structure measurements. In particular, annealing decreases the fraction of Pd atoms on nominally Cu 16e sites and the U-Cu pair-distance distribution width. This study provides quantitative information on the amount of disorder in UCu{sub 4Pd} and allows an assessment of its possible importance to the observed non-Fermi liquid behavior.

  4. Microstructure and Corrosion Behavior of the Cu-Pd-X Ternary...

    Office of Scientific and Technical Information (OSTI)

    Microstructure and Corrosion Behavior of the Cu-Pd-X Ternary Alloys for Hydrogen Separation Membranes Citation Details In-Document Search Title: Microstructure and Corrosion...

  5. Quantitative EDS Analysis of Nanometer-Scale Core/Shell Pd/Rh...

    Office of Scientific and Technical Information (OSTI)

    of Nanometer-Scale CoreShell PdRh Structures. Authors: Sugar, Joshua Daniel ; Kotula, Paul Gabriel 1 ; Robinson, David ; Cappillino, Patrick + Show Author Affiliations (Sandia...

  6. Towards ALD thin film stabilized single-atom Pd 1 catalysts

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Piernavieja-Hermida, Mar; Lu, Zheng; White, Anderson; Low, Ke-Bin; Wu, Tianpin; Elam, Jeffrey W.; Wu, Zili; Lei, Yu

    2016-07-27

    Supported precious metal single-atom catalysts have shown interesting activity and selectivity in recent studies. However, agglomeration of these highly mobile mononuclear surface species can eliminate their unique catalytic properties. In this paper, we study a strategy for synthesizing thin film stabilized single-atom Pd1 catalysts using atomic layer deposition (ALD). The thermal stability of the Pd1 catalysts is significantly enhanced by creating a nanocavity thin film structure. In situ infrared spectroscopy and Pd K-edge X-ray absorption spectroscopy (XAS) revealed that the Pd1 was anchored on the surface through chlorine sites. The thin film stabilized Pd1 catalysts were thermally stable under bothmore » oxidation and reduction conditions. The catalytic performance in the methanol decomposition reaction is found to depend on the thickness of protecting layers. While Pd1 catalysts showed promising activity at low temperature in a methanol decomposition reaction, 14 cycle TiO2 protected Pd1 was less active at high temperature. Pd L3 edge XAS indicated that the low reactivity compared with Pd nanoparticles is due to the strong adsorption of carbon monoxide even at 250 °C. Lastly, these results clearly show that the ALD nanocavities provide a basis for future design of single-atom catalysts that are highly efficient and stable.« less

  7. In-situ synchrotron energy-dispersive x-ray diffraction study of thin Pd foils with Pd:D and Pd:H concentrations up to 1:1

    SciTech Connect (OSTI)

    Knies, D. L.; Grabowski, K. S.; Dominguez, D. D.; Qadri, S. B.; Hubler, G. K.; Violante, V.; Hu, J. Z.; He, J. H.

    2012-10-15

    Time resolved, in-situ, energy dispersive x-ray diffraction was performed in an electrolysis cell during electrochemical loading of palladium foil cathodes with hydrogen and deuterium. Concentrations of H:Pd (D:Pd) up to 1:1 in 0.1 M LiOH (LiOD) in H{sub 2}O (D{sub 2}O) electrolyte were obtained, as determined by both the Pd lattice parameter and cathode resistivity. In addition, some indications on the kinetics of loading and deloading of hydrogen from the Pd surface were obtained. The alpha-beta phase transformations were clearly delineated but no new phases at high concentration were determined.

  8. Preparation and characterization of Pd{sub 2}Sn nanoparticles

    SciTech Connect (OSTI)

    Page, Katharine; Schade, Christina S.; Zhang, Jinping; Chupas, Peter J.; Chapman, Karena W.; Proffen, Thomas; Cheetham, Anthony K.; Seshadri, Ram

    2007-12-04

    We report a non-aqueous solution preparation of Pd{sub 2}Sn nanoparticles with sizes near 20 nm. The intermetallic compound with the Co{sub 2}Si structure has been characterized using transmission electron microscopy, Rietveld refinement of synchrotron X-ray and neutron powder diffraction, and real-space pair distribution function analysis of high-energy synchrotron X-ray scattering. We also present a description of the electronic structure of this covalent intermetallic using density functional calculations of the electronic structure.

  9. Significant Reduction in NiO Band Gap Upon Formation of LixNi1...

    Office of Scientific and Technical Information (OSTI)

    Significant Reduction in NiO Band Gap Upon Formation of LixNi1-xO alloys: Applications To Solar Energy Conversion Citation Details In-Document Search Title: Significant Reduction ...

  10. Epitaxial Growth of Intermetallic MnPt Films on Oxides and Large Exchange Bias

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Zhiqi; Biegalski, Michael D.; Hsu, Shang-Lin; Shang, Shunli; Marker, Cassie; Liu, Jian; Li, Li; Fan, Lisha S.; Meyer, Tricia L.; Wong, Anthony T.; et al

    2015-11-05

    High-quality epitaxial growth of intermetallic MnPt films on oxides is achieved, with potential for multiferroic heterostructure applications. Antisite-stabilized spin-flipping induces ferromagnetism in MnPt films, although it is robustly antiferromagnetic in bulk. Moreover, highly ordered antiferromagnetic MnPt films exhibit superiorly large exchange coupling with a ferromagnetic layer.

  11. Epitaxial growth of intermetallic MnPt films on oxides and large exchange bias

    SciTech Connect (OSTI)

    Liu, Zhiqi; Biegalski, Michael D.; Hsu, Shang-Lin; Shang, Shunli; Marker, Cassie; Liu, Jian; Li, Li; Fan, Lisha S.; Meyer, Tricia L.; Wong, Anthony T.; Nichols, John A.; Chen, Deyang; You, Long; Chen, Zuhuang; Wang, Kai; Wang, Kevin; Ward, Thomas Z.; Gai, Zheng; Lee, Ho Nyung; Sefat, Athena S.; Lauter, Valeria; Liu, Zi-kui; Christen, Hans M.

    2015-11-05

    High-quality epitaxial growth of intermetallic MnPt films on oxides is achieved, with potential for multiferroic heterostructure applications. Antisite-stabilized spin-flipping induces ferromagnetism in MnPt films, although it is robustly antiferromagnetic in bulk. Thus, highly ordered antiferromagnetic MnPt films exhibit superiorly large exchange coupling with a ferromagnetic layer.

  12. AcqGuide35pt1rev2.doc | Department of Energy

    Energy Savers [EERE]

    AcqGuide35pt1rev2.doc&0; AcqGuide35pt1rev2.doc&0; AcqGuide35pt1rev2.doc&0; More Documents & Publications Attachment FY2011-58 OPAM Chapter 35 - Research and Development...

  13. SF 6432-NI (02-22-10)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    be controlling. All deliverables under this Contract shall use andor be in the English language. NI14 - PAYMENT Contractor agrees to provide invoices within 60 days of...

  14. SF 6432-NI (04-95)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    be controlling. All deliverables under this Contract shall use andor be in the English language. NI15 - PAYMENT Contractor agrees to provide invoices within 60 days of...

  15. SF 6432-NI (04-95)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    be controlling. All deliverables under this Contract shall use andor be in the English language. NI14 - PAYMENT Contractor agrees to provide invoices within 60 days of...

  16. SF 6432-NI (04-95)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    descending order of precedence: (1) Section I; (2) SF 6432-NI, Section II. The English language version of this Contract shall be controlling. All deliverables under this...

  17. Ni Clusterbank Replacement Project | Argonne Leadership Computing...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ni Clusterbank Replacement Project Event Sponsor: Argonne Leadership Computing Facility Seminar Start Date: Oct 20 2015 - 12:00pm BuildingRoom: Building 241Room D173...

  18. Deuterium phase behavior in thin-film Pd

    SciTech Connect (OSTI)

    Munter, A.E.; Heuser, B.J.

    1998-07-01

    The absorption of deuterium from the gas phase into two Pd thin films 668 {Angstrom} and 1207 {Angstrom} thick was measured at room temperature with {ital in situ} neutron reflectometry. Room-temperature solubility isothermal curves, out-of-plane film expansion, and deuterium depth profiles were determined from fits to the neutron reflectivity data. The measurements demonstrate that the deuterium solubility behavior, both in solid solution and within the two-phase region, is strongly perturbed by the thin-film geometry, consistent with previous solubility measurements in the published literature. The phase behavior investigated here was observed to depend on film thickness and on deuterium cycling through the two-phase region. The 668-{Angstrom} film exhibited the greatest initial phase perturbation and most significant changes upon cycling. Upon repeated cycling, both films approach nearly identical deuterium isothermal solubility and out-of-plane expansion behaviors. The observed equilibrium out-of-plane expansion behavior was consistent with the films expanding under an in-plane clamping constraint imposed by the substrate. The effect of this substrate constraining force is to amplify the out-of-plane expansion beyond that expected in bulk Pd. Taken together, these measurements implicate the film/substrate interfacial clamping interaction as the origin of the perturbed hydrogen phase behavior in thin-film geometry. {copyright} {ital 1998} {ital The American Physical Society}

  19. Density functional studies of methanol decomposition on subnanometer Pd clusters.

    SciTech Connect (OSTI)

    Mehmood, F.; Greeley, J.; Curtiss, L. A.

    2009-12-31

    A density functional theory study of the decomposition of methanol on subnanometer palladium clusters (primarily Pd{sub 4}) is presented. Methanol dehydrogenation through C-H bond breaking to form hydroxymethyl (CH{sub 2}OH) as the initial step, followed by steps involving formation of hydroxymethylene (CHOH), formyl (CHO), and carbon monoxide (CO), is found to be the most favorable reaction pathway. A competing dehydrogenation pathway with O-H bond breaking as the first step, followed by formation of methoxy (CH{sub 3}O) and formaldehyde (CH{sub 2}O), is slightly less favorable. In contrast, pathways involving C-O bond cleavage are much less energetically favorable, and no feasible pathways involving C-O bond formation to yield dimethyl ether (CH{sub 3}OCH{sub 3}) are found. Comparisons of the results are made with methanol decomposition products adsorbed on more extended Pd surfaces; all reaction intermediates are found to bind slightly more strongly to the clusters than to the surfaces.

  20. The role of destabilization of palladium hydride on the hydrogen uptake of Pd-containing activated carbons

    SciTech Connect (OSTI)

    Bhat, Vinay V; Contescu, Cristian I; Gallego, Nidia C

    2009-01-01

    This paper reports on differences in stability of Pd hydride phases in palladium particles with various degrees of contact with microporous carbon supports. A sample containing Pd embedded in activated carbon fiber (Pd-ACF; 2 wt% Pd) was compared with commercial Pd nanoparticles deposited on microporous activated carbon (Pd-catalyst, 3 wt% Pd) and with support-free nanocrystalline palladium (Pd-black). The morphology of materials was characterized by electron microscopy, and the phase transformations were analyzed over a large range of hydrogen partial pressures (0.003 - 10 bar) and at several temperatures using in-situ X-ray diffraction. The results were verified with volumetric hydrogen uptake measurements. Results indicate that higher degree of Pd-carbon contacts for Pd particles embedded in a microporous carbon matrix induce efficient pumping of hydrogen out of -PdHx. It was also found that thermal cleaning of carbon surface groups prior to exposure to hydrogen further enhances the hydrogen pumping power of the microporous carbon support. In brief, this study highlights that the stability of -PdHx phase supported on carbon depends on the degree of contact between Pd-carbon and the nature of the carbon surface.

  1. First-principles study of the Pd–Si system and Pd(001)/SiC(001) hetero-structure

    SciTech Connect (OSTI)

    Turchi, P.E.A.; Ivashchenko, V.I.

    2014-11-01

    First-principles molecular dynamics simulations of the Pd(001)/3C–SiC(001) nano-layered structure were carried out at different temperatures ranging from 300 to 2100 K. Various PdSi (Pnma, Fm3m, P6m2, Pm3m), Pd2Si (P6⁻2m, P63/mmc, P3m1, P3⁻1m) and Pd3Si (Pnma, P6322, Pm3m, I4/mmm) structures under pressure were studied to identify the structure of the Pd/Si and Pd/C interfaces in the Pd/SiC systems at high temperatures. It was found that a large atomic mixing at the Pd/Si interface occurred at 1500–1800 K, whereas the Pd/C interface remained sharp even at the highest temperature of 2100 K. At the Pd/C interface, voids and a graphite-like clustering were detected. Palladium and silicon atoms interact at the Pd/Si interface to mostly form C22-Pd2Si and D011-Pd3Si fragments, in agreement with experiment.

  2. The effect of fuel sulfur level on the HC, CO and NOX conversion efficiencies of PD/RH, PT/RH, PD-only and tri-metal catalysts

    SciTech Connect (OSTI)

    DiCircco, D.M.; Adamczyk, A.A.; Patel, K.S.

    1995-12-31

    Due to additional requirements imposed by the 1990 amendments to the Clean Air Act, automotive emissions systems must perform at high efficiencies for 100,000 miles. However, fuels containing sulfur, can reduce the efficiency of many modern catalyst formulations. Additionally, the Northeast Ozone Transport Commission (OTC) has petitioned the US Environmental Protection Agency (EPA) to require region-wide adaptation of the California Low-Emission Vehicle standards without the application of California`s reformulated gasoline program which is necessary to keep the level of fuel sulfur low. As will be seen, this will result in reduced catalyst activity in the OTC, since typical gasolines contain sulfur levels which vary considerably. Gasolines containing 50ppmS and 500ppmS only represent the 10th and 75th percentile of US commercial summer fuels. As will be shown, these high levels of fuel sulfur will lower the performance of high activity catalyst formulations and may make compliance with LEV/ULEV emissions levels extremely difficult if not impossible without the adaptation of low-sulfur fuels.

  3. Single Pd atoms in activated carbon fibers and their contribution to hydrogen storage

    SciTech Connect (OSTI)

    Contescu, Cristian I; van Benthem, Klaus; Li, Sa; Bonifacio, Cecile S; Pennycook, Stephen J; Jena, Puru; Gallego, Nidia C

    2011-01-01

    Palladium-modified activated carbon fibers (Pd-ACF) were synthesized by meltspinning, carbonization and activation of an isotropic pitch carbon precursor premixed with an organometallic Pd compound. The hydrogen uptake at 25 oC and 20 bar on Pd- ACF exceeded the expected capacity based solely on Pd hydride formation and hydrogen physisorption on the microporous carbon support. Aberration-corrected scanning transmission electron microscopy (STEM) with sub- ngstrom spatial resolution provided unambiguous identification of isolated Pd atoms occurring in the carbon matrix that coexist with larger Pd particles. First principles calculations revealed that each single Pd atom can form Kubas-type complexes by binding up to three H2 molecules in the pressure range of adsorption measurements. Based on Pd atom concentration determined from STEM images, the contribution of various mechanisms to the excess hydrogen uptake measured experimentally was evaluated. With consideration of Kubas binding as a viable mechanism (along with hydride formation and physisorption to carbon support) the role of hydrogen spillover in this system may be smaller than previously thought.

  4. Networks of ultrasmall Pd/Cr bilayer nanowires as high performance hydrogen sensors.

    SciTech Connect (OSTI)

    Zeng, X.-Q.; Wang, Y.-L.; Deng, H.; Latimer, M. L.; Xiao, Z.-L.; Pearson, J.; Xu, T.; Wang, H.-H.; Welp, U.; Crabtree, G. W.; Kwok, W.-K.

    2011-01-01

    The newly developed hydrogen sensor, based on a network of ultrasmall pure palladium nanowires sputter-deposited on a filtration membrane, takes advantage of single palladium nanowires' characteristics of high speed and sensitivity while eliminating their nanofabrication obstacles. However, this new type of sensor, like the single palladium nanowires, cannot distinguish hydrogen concentrations above 3%, thus limiting the potential applications of the sensor. This study reports hydrogen sensors based on a network of ultrasmall Cr-buffered Pd (Pd/Cr) nanowires on a filtration membrane. These sensors not only are able to outperform their pure Pd counterparts in speed and durability but also allow hydrogen detection at concentrations up to 100%. The new networks consist of a thin layer of palladium deposited on top of a Cr adhesion layer 1-3 nm thick. Although the Cr layer is insensitive to hydrogen, it enables the formation of a network of continuous Pd/Cr nanowires with thicknesses of the Pd layer as thin as 2 nm. The improved performance of the Pd/Cr sensors can be attributed to the increased surface area to volume ratio and to the confinement-induced suppression of the phase transition from Pd/H solid solution ({alpha}-phase) to Pd hydride ({beta}-phase).

  5. Effects of lattice disorder in the UCu(5-x)Pd(x) system

    SciTech Connect (OSTI)

    Bauer, E.D.; Booth, C.H.; Kwei, G.H.; Chau, R.; Maple, M.B.

    2002-02-19

    The UCu5-x Pdx system exhibits non-Fermi liquid (NFL) behavior in thermodynamic and transport properties at low temperatures for Pd concentrations 0.9 less than or approximately x less than or approximately 1.5. The local structure around the U, Cu, and Pd atoms has been measured for

  6. Development of an inter-atomic potential for the Pd-H binary system.

    SciTech Connect (OSTI)

    Zimmerman, Jonathan A.; Hoyt, Jeffrey John; Leonard, Francois Leonard; Griffin, Joshua D.; Zhou, Xiao Wang

    2007-09-01

    Ongoing research at Sandia National Laboratories has been in the area of developing models and simulation methods that can be used to uncover and illuminate the material defects created during He bubble growth in aging bulk metal tritides. Previous efforts have used molecular dynamics calculations to examine the physical mechanisms by which growing He bubbles in a Pd metal lattice create material defects. However, these efforts focused only on the growth of He bubbles in pure Pd and not on bubble growth in the material of interest, palladium tritide (PdT), or its non-radioactive isotope palladium hydride (PdH). The reason for this is that existing inter-atomic potentials do not adequately describe the thermodynamics of the Pd-H system, which includes a miscibility gap that leads to phase separation of the dilute (alpha) and concentrated (beta) alloys of H in Pd at room temperature. This document will report the results of research to either find or develop inter-atomic potentials for the Pd-H and Pd-T systems, including our efforts to use experimental data and density functional theory calculations to create an inter-atomic potential for this unique metal alloy system.

  7. Vykson Formerly Turbine Developments NI Ltd | Open Energy Information

    Open Energy Info (EERE)

    Vykson Formerly Turbine Developments NI Ltd Jump to: navigation, search Name: Vykson (Formerly Turbine Developments (NI) Ltd) Place: Canterbury, England, United Kingdom Zip: BR6...

  8. The hydrogenation of Dy{sub 5}Pd{sub 2} followed by in situ methods

    SciTech Connect (OSTI)

    Kohlmann, H.; Talik, E.; Hansen, T.C.

    2012-03-15

    The hydrogenation behavior of the intermetallic compound Dy{sub 5}Pd{sub 2} was investigated by means of ex situ X-ray powder diffraction, in situ neutron powder diffraction and in situ differential scanning calorimetry. The structural model of Dy{sub 5}Pd{sub 2} with a palladium atom at the 32(e) position x, x, x (x Almost-Equal-To 0.22, 7/8 occupation) and a dysprosium atom at almost the same location (x Almost-Equal-To 0.18, 1/8 occupation) is confirmed. Upon heating the latter approaches x(Pd) and at T=399 K both positional parameters are indistinguishable. Dy{sub 5}Pd{sub 2} does not incorporate hydrogen (deuterium) into its crystal structure, however, starting at T=495 K reacts with hydrogen to non stoichiometric dysprosium dideuteride, DyD{sub 2+x}, following a parabolic rate law. In situ differential scanning calorimetry at various hydrogen pressures up to 2.5 MPa shows strongly exothermic signals, whose temperature onset depend on the gas pressure, corresponding to the formation of a mainly ionic hydride (DyH{sub 2+x}). - Graphical abstract: The hydrogenation of Dy5Pd2 is being followed by in situ neutron diffraction. Highlights: Black-Right-Pointing-Pointer Dy5Pd2 does not form a ternary hydride upon hydrogenation. Black-Right-Pointing-Pointer Dy5Pd2 decomposes to binary hydrides of dysprosium and palladium. Black-Right-Pointing-Pointer At T{>=}399 K Dy3 and Pd in the crystal structure of Dy5Pd2 share the same position. Black-Right-Pointing-Pointer The formation of DyD2+x at T=495 K and p(D2)=2.5 MPa follows a parabolic rate law.

  9. Low-temperature aqueous-phase reforming of ethanol on bimetallic PdZn catalysts

    SciTech Connect (OSTI)

    Xiong, Haifeng; DelaRiva, Andrew; Wang, Yong; Dayte, Abhaya

    2015-01-01

    Bimetallic PdZn catalysts supported on carbon black (CB) and carbon nanotubes (CNTs) were found to be selective for CO-free H-2 production from ethanol at low temperature (250 degrees C). On Pd, the H-2 yield was low (similar to 0.3 mol H-2/mol ethanol reacted) and the CH4/CO2 ratio was high (similar to 1.7). Addition of Zn to Pd formed the intermetallic PdZn beta phase (atomic ratio of Zn to Pd is 1) with increased H-2 yield (similar to 1.9 mol H-2/mol ethanol reacted) and CH4/CO2 ratio of <1. The higher H-2 yield and low CH4 formation was related to the improved dehydrogenation activity of the L1(0) PdZn beta phase. The TOF increased with particle size and the CNTs provided the most active and selective catalysts, which may be ascribed to pore-confinement effects. Furthermore, no significant changes in either the supports or the PdZn beta particles was found after aqueous-phase reforming (APR) indicating that the metal nanoparticles and the carbon support are hydrothermally stable in the aqueous phase at elevated temperatures and pressures (>200 degrees C, 65 bar). No CO was detected for all the catalysts performed in aqueous-phase reaction, indicating that both monometallic Pd and bimetallic PdZn catalysts have high water-gas shift activity during APR. However, the yield of H-2 is considerably lower than the theoretical value of 6 H-2 per mole ethanol which is due to the presence of oxygenated products and methane on the PdZn catalysts.

  10. Non-local magnetoresistance in YIG/Pt nanostructures

    SciTech Connect (OSTI)

    Goennenwein, Sebastian T. B. Pernpeintner, Matthias; Gross, Rudolf; Huebl, Hans; Schlitz, Richard; Ganzhorn, Kathrin; Althammer, Matthias

    2015-10-26

    We study the local and non-local magnetoresistance of thin Pt strips deposited onto yttrium iron garnet. The local magnetoresistive response, inferred from the voltage drop measured along one given Pt strip upon current-biasing it, shows the characteristic magnetization orientation dependence of the spin Hall magnetoresistance. We simultaneously also record the non-local voltage appearing along a second, electrically isolated, Pt strip, separated from the current carrying one by a gap of a few 100 nm. The corresponding non-local magnetoresistance exhibits the symmetry expected for a magnon spin accumulation-driven process, confirming the results recently put forward by Cornelissen et al. [“Long-distance transport of magnon spin information in a magnetic insulator at room temperature,” Nat. Phys. (published online 14 September 2015)]. Our magnetotransport data, taken at a series of different temperatures as a function of magnetic field orientation, rotating the externally applied field in three mutually orthogonal planes, show that the mechanisms behind the spin Hall and the non-local magnetoresistance are qualitatively different. In particular, the non-local magnetoresistance vanishes at liquid Helium temperatures, while the spin Hall magnetoresistance prevails.

  11. Inelastic magnetic neutron scattering in CePd{sub 3}.

    SciTech Connect (OSTI)

    Lawrence, J. M.; Fanelli, V. R.; Goremychkin, E. A.; Osborn, R.; Bauer, E. D.; McClellan, K. J.; Christianson, A. D.; Univ. of California at Irvine; LANL; ORNL

    2008-01-01

    We have performed time-of-flight neutron scattering measurements on a single crystal of the intermediate valence compound CePd{sub 3}. At 10 K, a Kondo-esque inelastic magnetic scattering peak occurs near {Delta}E = 60 meV with maximum intensity for momentum transfer Q near the (1/2, 1/2, 0) zone boundary. Spectral weight is transferred to lower energy as Q varies until at zone center the intensity at 60 meV is considerably weaker. These results are in qualitative accord with predictions of the Anderson lattice. The Q-dependence may resolve an older controversy concerning the low-temperature scattering. We discuss the relationship of these results to our recent results in YbAl{sub 3}.

  12. Magnetoelectric switching of perpendicular exchange bias in Pt/Co/?-Cr{sub 2}O{sub 3}/Pt stacked films

    SciTech Connect (OSTI)

    Toyoki, Kentaro; Shiratsuchi, Yu Kobane, Atsushi; Nakatani, Ryoichi; Mitsumata, Chiharu; Kotani, Yoshinori; Nakamura, Tetsuya

    2015-04-20

    We report the realization of magnetoelectric switching of the perpendicular exchange bias in Pt/Co/?-Cr{sub 2}O{sub 3}/Pt stacked films. The perpendicular exchange bias was switched isothermally by the simultaneous application of magnetic and electric fields. The threshold electric field required to switch the perpendicular exchange bias was found to be inversely proportional to the magnetic field, which confirmed the magnetoelectric mechanism of the process. The observed temperature dependence of the threshold electric field suggested that the energy barrier of the antiferromagnetic spin reversal was significantly lower than that assuming the coherent rotation. Pulse voltage measurements indicated that the antiferromagnetic domain propagation dominates the switching process. These results suggest an analogy of the electric-field-induced magnetization with a simple ferromagnet.

  13. Thermally Stable Nanocatalyst for High Temperature Reactions: Pt-Mesoporous Silica Core-Shell Nanoparticles

    SciTech Connect (OSTI)

    Joo, Sang Hoon; Park, J.Y.; Tsung, C.-K.; Yamada, Y.; Yang, P.; Somorjai, G.A.

    2008-10-25

    Recent advances in colloidal synthesis enabled the precise control of size, shape and composition of catalytic metal nanoparticles, allowing their use as model catalysts for systematic investigations of the atomic-scale properties affecting catalytic activity and selectivity. The organic capping agents stabilizing colloidal nanoparticles, however, often limit their application in high-temperature catalytic reactions. Here we report the design of a high-temperature stable model catalytic system that consists of Pt metal core coated with a mesoporous silica shell (Pt{at}mSiO{sub 2}). While inorganic silica shells encaged the Pt cores up to 750 C in air, the mesopores directly accessible to Pt cores made the Pt{at}mSiO{sub 2} nanoparticles as catalytically active as bare Pt metal for ethylene hydrogenation and CO oxidation. The high thermal stability of Pt{at}mSiO{sub 2} nanoparticles permitted high-temperature CO oxidation studies, including ignition behavior, which was not possible for bare Pt nanoparticles because of their deformation or aggregation. The results suggest that the Pt{at}mSiO{sub 2} nanoparticles are excellent nanocatalytic systems for high-temperature catalytic reactions or surface chemical processes, and the design concept employed in the Pt{at}mSiO{sub 2} core-shell catalyst can be extended to other metal-metal oxide compositions.

  14. Activity and selectivity control by niobium for the preferential oxidation of co on pt supported catalysts

    SciTech Connect (OSTI)

    Guerrero, S.; Miller, J.T.; Wolf, E.E.

    2010-10-22

    The promotional effect of Nb on Pt supported on alumina or on niobia, was studied for the preferential oxidation of CO (PROX) in hydrogen. The results show a unique effect of Nb as a promoter to Pt. At low Nb loadings on Pt/alumina, the CO oxidation activity and selectivity are significantly increased. The CO selectivity is 100% at conversions up to about 60%. For Pt supported on Nb{sub 2}O{sub 5}, however, the CO oxidation activity is strongly suppressed with low CO conversion but high H{sub 2} oxidation activity. Pt on niobia, therefore, is poorly selective for the PROX reaction, but is an active hydrogen oxidation catalyst, resistant to CO poisoning. For Pt supported on highly loaded Nb-alumina or Nb{sub 2}O{sub 5}, XPS indicate an increase in the Pt and Nb oxidation states. These surface changes also correlate with changes in the DRIFTS spectra suggesting that CO is more weakly adsorbed on Pt/Nb{sub 2}O{sub 5} compared to Pt/Al{sub 2}O{sub 3}, or Pt/Nb-Al{sub 2}O{sub 3}.

  15. H2 production from simulated coal syngas containing H2S in multi-tubular Pd and 80 wt% Pd-20 wt% Cu membrane reactors

    SciTech Connect (OSTI)

    Iyoha, O.; Enick, R.M.; Killmeyer, R.P.; Howard, B.H.; Ciocco, M.V.; Morreale, B.

    2007-12-01

    99.7% conversion of CO in a simulated syngas feed containing 53% CO, 35% H2 and 12% CO2 was achieved via the water–gas shift (WGS) reaction in a counter-current Pd multi-tube membrane reactor (MR) at 1173 K and 2 s residence time. This conversion is significantly greater than the 32% equilibrium conversion associated with a conventional (non-membrane) reactor primarily due to the high rate of H2 extraction from the reaction zone through the Pd membranes at elevated temperatures. Furthermore, nearly complete H2 recovery was attained in the permeate, resulting in the simultaneous production of a high-pressure CO2 (>99%) retentate stream after condensation of the steam. When Pd80 wt%Cu tubes were used in the reactor, a significantly lower CO conversion of 68% was attained at comparable residence times, probably due to the lower H2 permeance of the alloy. When H2S was added to the syngas feed and the H2S-to-H2 ratio was maintained below the threshold required for thermodynamically stable sulfides to form, the Pd and Pd80 wt%Cu MRs retained their mechanical integrity and H2 selectivity, but a precipitous drop in CO conversion was observed due to deactivation of the catalytic surface. The Pd and Pd80 wt%Cu MRs were observed to fail within minutes after increasing the H2S-to-H2 ratio to levels above that expected for thermodynamically stable sulfides to form, as evidenced by rupturing of the membrane tubes. SEM–EDS analyses of the membranes suggested that at high H2S-to-H2 ratios, the H2S compromised the mechanical integrity of the MRs by preferentially attacking the grain boundary region.

  16. Novel Pt/Mg(In)(Al)O catalysts for ethane and propane dehydrogenation

    SciTech Connect (OSTI)

    Sun, Pingping; Siddiqi, Georges; Vining, William C.; Chi, Miaofang; Bell, Alexis T.

    2011-10-28

    Catalysts for the dehydrogenation of light alkanes were prepared by dispersing Pt on the surface of a calcined hydrotalcite-like support containing indium, Mg(In)(Al)O. Upon reduction in H{sub 2} at temperatures above 673 K, bimetallic particles of PtIn are observed by TEM, which have an average diameter of 1 nm. Analysis of Pt LIII-edge extended X-ray absorption fine structure (EXAFS) data shows that the In content of the bimetallic particles increases with increasing bulk In/Pt ratio and reduction temperature. Pt LIII-edge X-ray absorption near edge structure (XANES) indicates that an increasing donation of electronic charge from In to Pt occurs with increasing In content in the PtIn particles. The activity and selectivity of the Pt/Mg(In)(Al)O catalysts for ethane and propane dehydrogenation reactions are strongly dependent on the bulk In/Pt ratio. For both reactants, maximum activity was achieved for a bulk In/Pt ratio of 0.48, and at this In/Pt ratio, the selectivity to alkene was nearly 100%. Coke deposition was observed after catalyst use for either ethane or propane dehydrogenation, and it was observed that the alloying of Pt with In greatly reduced the amount of coke deposited. Characterization of the deposit by Raman spectroscopy indicates that the coke is present as highly disordered graphite particles <30 nm in diameter. While the amount of coke deposited during ethane and propane dehydrogenation are comparable, the effects on activity are dependent on reactant composition. Coke deposition had no effect on ethane dehydrogenation activity, but caused a loss in propane dehydrogenation activity. This difference is attributed to the greater ease with which coke produced on the surface of PtIn nanoparticles migrates to the support during ethane dehydrogenation versus propane dehydrogenation.

  17. Theoretical prediction of the fundamental properties for the ternary Li{sub 2}PtH{sub 6} and Na{sub 2}PtH{sub 6}

    SciTech Connect (OSTI)

    Ghebouli, M.A.; Choutri, H.; Bouarissa, N.; Ghebouli, B.; Bouhemadou, A.; Department of Physics and Astronomy, College of Science, King Saud University, PO Box 2455, Riyadh 11451 ; Soyalp, F.; Ucgun, E.; Ocak, H.Y.

    2012-12-15

    Li{sub 2}PtH{sub 6} and Na{sub 2}PtH{sub 6} are good candidate for hydrogen storage. The structural, elastic, electronic and optical properties of Li{sub 2}PtH{sub 6} and Na{sub 2}PtH{sub 6} compounds have been investigated using pseudo-potential plane-wave method based on the density functional theory. Computed lattice constant and H atom positional parameter at equilibrium agree well with the available experimental data. A quadratic pressure dependence of the elastic stiffness is found. A set of isotropic elastic parameters and related properties, namely bulk and shear moduli, Young's modulus, Poisson's ratio, average sound velocity and Debye temperature are numerically estimated in the framework of the Voigt-Reuss-Hill approximation for Li{sub 2}PtH{sub 6} and Na{sub 2}PtH{sub 6} polycrystalline aggregate. The analyses of the band structure indicates that Li{sub 2}PtH{sub 6} and Na{sub 2}PtH{sub 6} are indirect gap semiconductors. The static dielectric constant and static refractive index are inversely proportional to the fundamental gap. Highlights: Black-Right-Pointing-Pointer We predict elastic moduli, energy gaps and optical parameters. Black-Right-Pointing-Pointer Electron effective mass is anisotropic. Black-Right-Pointing-Pointer Li{sub 2}PtH{sub 6} and Na{sub 2}PtH{sub 6} are indirect gap semiconductors. Black-Right-Pointing-Pointer The contribution to the optical spectra from main transitions are predicted.

  18. Hydrogen-induced atomic rearrangement in MgPd{sub 3}

    SciTech Connect (OSTI)

    Kohlmann, H. . E-mail: h.kohlmann@mx.uni-saarland.de; Renaudin, G.; Yvon, K.; Wannek, C.; Harbrecht, B.

    2005-04-15

    The hydrogenation behavior of MgPd{sub 3} has been studied by in situ X-ray powder diffraction and by neutron powder diffraction. At room temperature and p {approx}500kPa hydrogen pressure its structure is capable of incorporating up to one hydrogen atom per formula unit ({alpha}-MgPd{sub 3}H{sub {approx}}{sub 1}), thereby retaining a tetragonal ZrAl{sub 3}-type metal atom arrangement. Upon heating to 750K in a hydrogen atmosphere of 610kPa it transforms into a cubic modification with AuCu{sub 3}-type metal atom arrangement ({beta}-MgPd{sub 3}H{sub {approx}}{sub 0.7}). Neutron diffraction on the deuteride reveals an anion deficient anti-perovskite-type structure ({beta}-MgPd{sub 3}D{sub 0.67}, a=398.200(7)pm) in which octahedral sites surrounded exclusively by palladium atoms are occupied by deuterium. Complete removal of hydrogen (480K, 1Pa) stabilizes a new binary modification ({beta}-MgPd{sub 3}, a=391.78(2)pm) crystallizing with a primitive cubic AuCu{sub 3}-type structure. Mechanical treatment (grinding) transforms both {alpha} and {beta} modifications of MgPd{sub 3} into a cubic face-centered solid solution Mg{sub 0.25}Pd{sub 0.75} showing a random distribution of magnesium and palladium atoms.

  19. Model for the Prediction of the Hydriding Thermodynamics of Pd-Rh-Co Ternary Alloys

    SciTech Connect (OSTI)

    Teter, D.F.; Thoma, D.J.

    1999-03-01

    A dilute solution model (with respect to the substitutional alloying elements) has been developed, which accurately predicts the hydride formation and decomposition thermodynamics and the storage capacities of dilute ternary Pd-Rh-Co alloys. The effect of varying the rhodium and cobalt compositions on the thermodynamics of hydride formation and decomposition and hydrogen capacity of several palladium-rhodium-cobalt ternary alloys has been investigated using pressure-composition (PC) isotherms. Alloying in the dilute regime (<10 at.%) causes the enthalpy for hydride formation to linearly decrease with increasing alloying content. Cobalt has a stronger effect on the reduction in enthalpy than rhodium for equivalent alloying amounts. Also, cobalt reduces the hydrogen storage capacity with increasing alloying content. The plateau thermodynamics are strongly linked to the lattice parameters of the alloys. A near-linear dependence of the enthalpy of hydride formation on the lattice parameter was observed for both the binary Pd-Rh and Pd-Co alloys, as well as for the ternary Pd-Rh-Co alloys. The Pd-5Rh-3Co (at. %) alloy was found to have similar plateau thermodynamics as a Pd-10Rh alloy, however, this ternary alloy had a diminished hydrogen storage capacity relative to Pd-10Rh.

  20. Modifying structure-sensitive reactions by addition of Zn to Pd

    SciTech Connect (OSTI)

    Childers, David J.; Schweitzer, Neil M.; Kamali Shahari, Seyed Mehdi; Rioux, Robert M.; Miller, Jeffrey T.; Meyer, Randall J.

    2014-10-01

    Silica-supported Pd and PdZn nanoparticles of a similar size were evaluated for neopentane hydrogenolysis/isomerization and propane hydrogenolysis/dehydrogenation. Monometallic Pd showed high neopentane hydrogenolysis selectivity. Addition of small amounts of Zn to Pd lead Pd–Zn scatters in the EXAFS spectrum and an increase in the linear bonded CO by IR. In addition, the neopentane turnover rate decreased by nearly 10 times with little change in the selectivity. Increasing amounts of Zn lead to greater Pd–Zn interactions, higher linear-to-bridging CO ratios by IR and complete loss of neopentane conversion. Pd NPs also had high selectivity for propane hydrogenolysis and thus were poorly selective for propylene. The PdZn bimetallic catalysts, however, were able to preferentially catalyze dehydrogenation, were not active for propane hydrogenolysis, and thus were highly selective for propylene formation. The decrease in hydrogenolysis selectivity was attributed to the isolation of active Pd atoms by inactive metallic Zn,demonstrating that hydrogenolysis requires a particular reactive ensemble whereas propane dehydrogenation does not.

  1. Hydrogen responses of ultrathin Pd films and nanowire networks with a Ti buffer layer.

    SciTech Connect (OSTI)

    Zeng, X. Q.; Wang, Y. L.; Xiao, Z. L.; Latimer, M. L.; Xu, T.; Kwok, W. K.

    2012-01-01

    We report on hydrogen responses of ultrathin films and nanowire networks of palladium on titanium buffered silicon substrates and filtration membranes, respectively. We found that in both systems signatures such as retarding responses and saturation of the resistance changes at high hydrogen concentrations associated with the transition from Pd/H solid solution to Pd hydride diminish with decreasing the thickness of the palladium layer from 7 to 2 nm. Our results not only reveal a new way to suppress the phase transition in Pd/H system but also provide an alternative approach to achieve fast and sensitive hydrogen sensors with a wide concentration detection range.

  2. PdAgAu alloy with high resistance to corrosion by H{sub 2}S

    SciTech Connect (OSTI)

    Braun, Fernando; Miller, James B.; Gellman, Andrew J.; Tarditi, Ana M.; Fleutot, Benoit; Petro, Kondratyuk, Cornaglia, Laura M

    2012-12-01

    PdAgAu alloy films were prepared on porous stainless steel supports by sequential electroless deposition. Two specific compositions, Pd{sub 83}Ag{sub 2}Au{sub 15} and Pd{sub 74}Ag{sub 14}Au{sub 12}, were studied for their sulfur tolerance. The alloys and a reference Pd foil were exposed to 1000 H{sub 2}S/H{sub 2} at 623 K for periods of 3 and 30 hours. The microstructure, morphology and bulk composition of both nonexposed and H{sub 2}S-exposed samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). XRD and SEM analysis revealed time-dependent growth of a bulk Pd{sub 4}S phase on the Pd foil during H{sub 2}S exposure. In contrast, the PdAgAu ternary alloys displayed the same FCC structure before and after H{sub 2}S exposure. In agreement with the XRD and SEM results, sulfur was not detected in the bulk of either ternary alloy samples by EDS, even after 30 hours of H{sub 2}S exposure. X-ray photoelectron spectroscopy (XPS) depth profiles were acquired for both PdAgAu alloys after 3 and 30 hours of exposure to characterize sulfur contamination near their surfaces. Very low S 2p and S 2s XPS signals were observed at the top-surfaces of the PdAgAu alloys, and those signals disappeared before the etch depth reached ~ 10 nm, even for samples exposed to H{sub 2}S for 30 hours. The depth profile analyses also revealed silver and gold segregation to the surface of the alloys; preferential location of Au on the alloys surface may be related to their resistance to bulk sulfide formation. In preliminary tests, a PdAgAu alloy membrane displayed higher initial H{sub 2} permeability than a similarly prepared pure Pd sample and, consistent with resistance to bulk sulfide formation, lower permeability loss in H{sub 2}S than pure Pd.

  3. Antiferromagnetic Kondo lattice in the layered compound CePd1–xBi₂ and comparison to the superconductor LaPd1–xBi₂

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Han, Fei; Wan, Xiangang; Phelan, Daniel; Stoumpos, Constantinos C.; Sturza, Mihai; Malliakas, Christos D.; Li, Qing'an; Han, Tian-Heng; Zhao, Qingbiao; Chung, Duck Young; et al

    2015-07-13

    The layered compound CePd1–xBi₂ with the tetragonal ZrCuSi₂-type structure was obtained from excess Bi flux. Magnetic susceptibility data of CePd1–xBi₂ show an antiferromagnetic ordering below 6 K and are anisotropic along the c axis and the ab plane. The anisotropy is attributed to crystal-electric-field (CEF) effects and a CEF model which is able to describe the susceptibility data is given. An enhanced Sommerfeld coefficient γ of 0.191 J mol Ce⁻¹ K⁻² obtained from specific-heat measurement suggests a moderate Kondo effect in CePd1–xBi₂. Other than the antiferromagnetic peak at 6 K, the resistivity curve shows a shoulderlike behavior around 75 Kmore » which could be attributed to the interplay between Kondo and CEF effects. Magnetoresistance and Hall-effect measurements suggest that the interplay reconstructs the Fermi-surface topology of CePd1–xBi₂ around 75 K. Electronic structure calculations reveal that the Pd vacancies are important to the magnetic structure and enhance the CEF effects which quench the orbital moment of Ce at low temperatures.« less

  4. Layering and temperature-dependent magnetization and anisotropy of naturally produced Ni/NiO multilayers

    SciTech Connect (OSTI)

    Pappas, S. D.; Trachylis, D.; Velgakis, M. J.; Kapaklis, V.; Joensson, P. E.; Papaioannou, E. Th.; Delimitis, A.; Poulopoulos, P.; Fumagalli, P.; Politis, C.

    2012-09-01

    Ni/NiO multilayers were grown by magnetron sputtering at room temperature, with the aid of the natural oxidation procedure. That is, at the end of the deposition of each single Ni layer, air is let to flow into the vacuum chamber through a leak valve. Then, a very thin NiO layer ({approx}1.2 nm) is formed. Simulated x-ray reflectivity patterns reveal that layering is excellent for individual Ni-layer thickness larger than 2.5 nm, which is attributed to the intercalation of amorphous NiO between the polycrystalline Ni layers. The magnetization of the films, measured at temperatures 5-300 K, has almost bulk-like value, whereas the films exhibit a trend to perpendicular magnetic anisotropy (PMA) with an unusual significant positive interface anisotropy contribution, which presents a weak temperature dependence. The power-law behavior of the multilayers indicates a non-negligible contribution of higher order anisotropies in the uniaxial anisotropy. Bloch-law fittings for the temperature dependence of the magnetization in the spin-wave regime show that the magnetization in the multilayers decreases faster as a function of temperature than the one of bulk Ni. Finally, when the individual Ni-layer thickness decreases below 2 nm, the multilayer stacking vanishes, resulting in a dramatic decrease of the interface magnetic anisotropy and consequently in a decrease of the perpendicular magnetic anisotropy.

  5. Ion irradiation induced defect evolution in Ni and Ni-based FCC equiatomic binary alloys

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jin, Ke; Zhang, Yanwen; Bei, Hongbin

    2016-01-01

    In order to explore the chemical effects on radiation response of alloys with multi-principal elements, defect evolution under Au ion irradiation was investigated in the elemental Ni, equiatomic NiCo and NiFe alloys. Single crystals were successfully grown in an optical floating zone furnace and their (100) surfaces were irradiated with 3 MeV Au ions at fluences ranging from 1 × 1013 to 5 × 1015 ions cm–2 at room temperature. The irradiation-induced defect evolution was analyzed by using ion channeling technique. Experiment shows that NiFe is more irradiation-resistant than NiCo and pure Ni at low fluences. With continuously increasing themore » ion fluences, damage level is eventually saturated for all materials but at different dose levels. The saturation level in pure Ni appears at relatively lower irradiation fluence than the alloys, suggesting that damage accumulation slows down in the alloys. Here, under high-fluence irradiations, pure Ni has wider damage ranges than the alloys, indicating that defects in pure Ni have high mobility.« less

  6. Ion irradiation induced defect evolution in Ni and Ni-based FCC equiatomic binary alloys

    SciTech Connect (OSTI)

    Jin, Ke; Zhang, Yanwen; Bei, Hongbin

    2016-01-01

    In order to explore the chemical effects on radiation response of alloys with multi-principal elements, defect evolution under Au ion irradiation was investigated in the elemental Ni, equiatomic NiCo and NiFe alloys. Single crystals were successfully grown in an optical floating zone furnace and their (100) surfaces were irradiated with 3 MeV Au ions at fluences ranging from 1 × 1013 to 5 × 1015 ions cm–2 at room temperature. The irradiation-induced defect evolution was analyzed by using ion channeling technique. Experiment shows that NiFe is more irradiation-resistant than NiCo and pure Ni at low fluences. With continuously increasing the ion fluences, damage level is eventually saturated for all materials but at different dose levels. The saturation level in pure Ni appears at relatively lower irradiation fluence than the alloys, suggesting that damage accumulation slows down in the alloys. Here, under high-fluence irradiations, pure Ni has wider damage ranges than the alloys, indicating that defects in pure Ni have high mobility.

  7. Microsoft Word - NiR.doc

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    In bacteria, NO is produced by nitrite reductase (NiR), a copper-containing enzyme, which ... required to define the mode of binding of the ligands to the active site copper. ...

  8. SF 6432-NI (04-95)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    6432-NI (11-03-2010) SECTION II STANDARD TERMS AND CONDITIONS FOR FIXED PRICE CONTRACTS WITH THE NEWLY INDEPENDENT STATES OF THE FORMER SOVIET UNION INDEX OF CLAUSES. THE FOLLOWING CLAUSES APPLY TO REQUESTS FOR QUOTATION AND CONTRACTS AS INDICATED UNLESS SPECIFICALLY DELETED, OR EXCEPT TO THE EXTENT THEY ARE SPECIFICALLY SUPPLEMENTED OR AMENDED IN WRITING IN THE SIGNATURE PAGE OR SECTION I. NI01 - ACCEPTANCE OF TERMS AND CONDITIONS Contractor, by signing this Agreement, beginning performance,

  9. Monolayer PtSe 2 , a New Semiconducting Transition-Metal-Dichalcogenide, Epitaxially Grown by Direct Selenization of Pt

    SciTech Connect (OSTI)

    Wang, Yeliang; Li, Linfei; Yao, Wei; Song, Shiru; Sun, J. T.; Pan, Jinbo; Ren, Xiao; Li, Chen; Okunishi, Eiji; Wang, Yu-Qi; Wang, Eryin; Shao, Yan; Zhang, Y. Y.; Yang, Hai-tao; Schwier, Eike F.; Iwasawa, Hideaki; Shimada, Kenya; Taniguchi, Masaki; Cheng, Zhaohua; Zhou, Shuyun; Du, Shixuan; Pennycook, Stephen J.; Pantelides, Sokrates T.; Gao, Hong-Jun

    2015-05-21

    For single-layer transition-metal dichalcogenides (TMDs) receive significant attention due to their intriguing physical properties for both fundamental research and potential applications in electronics, optoelectronics, spintronics, catalysis, and so on. Here, we demonstrate the epitaxial growth of high-quality single-crystal, monolayer platinum diselenide (PtSe2), a new member of the layered TMDs family, by a single step of direct selenization of a Pt(111) substrate. We found that a combination of atomic-resolution experimental characterizations and first-principle theoretic calculations reveals the atomic structure of the monolayer PtSe2/Pt(111). Angle-resolved photoemission spectroscopy measurements confirm for the first time the semiconducting electronic structure of monolayer PtSe2 (in contrast to its semimetallic bulk counterpart). The photocatalytic activity of monolayer PtSe2 film is evaluated by a methylene-blue photodegradation experiment, demonstrating its practical application as a promising photocatalyst. Moreover, circular polarization calculations predict that monolayer PtSe2 has also potential applications in valleytronics.

  10. Ultralow charge-transfer resistance with ultralow Pt loading for hydrogen evolution and oxidation using Ru@Pt core-shell nanocatalysts

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Jia X.; Zhang, Yu; Capuano, Christopher B.; Ayers, Katherine E.

    2015-07-15

    We evaluated the activities of well-defined Ru@Pt core-shell nanocatalysts for hydrogen evolution and oxidation reactions (HER-HOR) using hanging strips of gas diffusion electrode (GDE) in solution cells. With gas transport limitation alleviated by micro-porous channels in the GDEs, the charge transfer resistances (CTRs) at the hydrogen reversible potential were conveniently determined from linear fit of ohmic-loss-corrected polarization curves. In 1M HClO₄ at 23°C, a CTR as low as 0.04 Ω cm² was obtained with only 20 μg cm⁻² Pt and 11 μg cm⁻² Ru using the carbon-supported Ru@Pt with 1:1 Ru:Pt atomic ratio. Derived from temperature-dependent CTRs, the activation barriermore » of the Ru@Pt catalyst for the HER-HOR in acids is 0.2 eV or 19 kJ mol⁻¹. Using the Ru@Pt catalyst with total metal loadings <50 μg cm⁻² for the HER in proton-exchange-membrane water electrolyzers, we recorded uncompromised activity and durability compared to the baseline established with 3 mg cm⁻² Pt black.« less

  11. Ultralow charge-transfer resistance with ultralow Pt loading for hydrogen evolution and oxidation using Ru@Pt core-shell nanocatalysts

    SciTech Connect (OSTI)

    Wang, Jia X.; Zhang, Yu; Capuano, Christopher B.; Ayers, Katherine E.

    2015-07-15

    We evaluated the activities of well-defined Ru@Pt core-shell nanocatalysts for hydrogen evolution and oxidation reactions (HER-HOR) using hanging strips of gas diffusion electrode (GDE) in solution cells. With gas transport limitation alleviated by micro-porous channels in the GDEs, the charge transfer resistances (CTRs) at the hydrogen reversible potential were conveniently determined from linear fit of ohmic-loss-corrected polarization curves. In 1M HClO₄ at 23°C, a CTR as low as 0.04 Ω cm² was obtained with only 20 μg cm⁻² Pt and 11 μg cm⁻² Ru using the carbon-supported Ru@Pt with 1:1 Ru:Pt atomic ratio. Derived from temperature-dependent CTRs, the activation barrier of the Ru@Pt catalyst for the HER-HOR in acids is 0.2 eV or 19 kJ mol⁻¹. Using the Ru@Pt catalyst with total metal loadings <50 μg cm⁻² for the HER in proton-exchange-membrane water electrolyzers, we recorded uncompromised activity and durability compared to the baseline established with 3 mg cm⁻² Pt black.

  12. Phase Stability for the Pd-Si System. First-Principles, Experiments, and Solution-Based Modeling

    SciTech Connect (OSTI)

    Zhou, S. H.; Huo, Y.; Napolitano, Ralph E.

    2015-11-05

    Relative stabilities of the compounds in the binary Pd-Si system were assessed using first-principles calculations and experimental methods. Calculations of lattice parameters and enthalpy of formation indicate that Pd5Si-μ, Pd9Si2-α, Pd3 Si-β, Pd2 Si-γ, and PdSi-δ are the stable phases at 0 K (-273 °C). X-ray diffraction analyses (XRD) and electron probe microanalysis (EPMA) of the as-solidified and heat-treated samples support the computational findings, except that the PdSi-δ phase was not observed at low temperature. Considering both experimental data and first-principles results, the compounds Pd 5 Si-μ, Pd9 Si2-α, Pd3Si-β, and Pd2Si-γ are treated as stable phases down to 0 K (-273 °C), while the PdSi-δ is treated as being stable over a limited range, exhibiting a lower bound. Using these findings, a comprehensive solution-based thermodynamic model is formulated for the Pd-Si system, permitting phase diagram calculation. Moreover, the liquid phase is described using a three-species association model and other phases are treated as solid solutions, where a random substitutional model is adopted for Pd-fcc and Si-dia, and a two-sublattice model is employed for Pd5Si-μ, Pd9Si2-α, Pd3Si-β, Pd2Si-γ, and PdSi-δ. Model parameters are fitted using available experimental data and first-principles data, and the resulting phase diagram is reported over the full range of compositions.

  13. Mitigation of the Impact of Pt Contamination on Cu-Zeolite SCR...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Mitigation of the Impact of Pt Contamination on Cu-Zeolite SCR Catalyst Performance Investigates operating conditions under which PGM elements get volatilized and transferred onto ...

  14. Fabrication of two-dimensional Au at FePt core-shell nanoparticle...

    Office of Scientific and Technical Information (OSTI)

    In this report, we experimentally demonstrate that single platinum nanoparticles exhibit ... This finding is exploited for the parallel Au encapsulation of FePt nanoparticles arranged ...

  15. Effect of substrate temperature on the magnetic properties of epitaxial sputter-grown Co/Pt

    SciTech Connect (OSTI)

    Mihai, A. P.; Whiteside, A. L.; Canwell, E. J.; Marrows, C. H.; Moore, T. A.; Benitez, M. J.; McGrouther, D.; McVitie, S.; McFadzean, S.

    2013-12-23

    Epitaxial Co/Pt films have been deposited by dc-magnetron sputtering onto heated C-plane sapphire substrates. X-ray diffraction, the residual resistivity, and transmission electron microscopy indicate that the Co/Pt films are highly ordered on the atomic scale. The coercive field and the perpendicular magnetic anisotropy increase as the substrate temperature is increased from 100250?C during deposition of the Co/Pt. Measurement of the domain wall creep velocity as a function of applied magnetic field yields the domain wall pinning energy, which scales with the coercive field. Evidence for an enhanced creep velocity in highly ordered epitaxial Co/Pt is found.

  16. 48pt0ValueEngineeringinMOContracts.pdf | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    8pt0ValueEngineeringinMOContracts.pdf More Documents & Publications Chapter 48 - Value Engineering CX-008874: Categorical Exclusion Determination CX-000908: Categorical Exclusion...

  17. Anomalous behavior of the Pd/D system. Final report, June 1989-August 1993

    SciTech Connect (OSTI)

    Szpak, S.J.; Mosier-Boss, P.A.

    1995-09-01

    In a news conference on 23 March 1989, Martin Fleischmann and Stanley Pons announced that nuclear events could be initiated by the electrochemical compression of deuterium into a palladium lattice. When researchers around the world tried to reproduce the effects described by Pons and Fleischmann in their laboratories, the results were mixed. The nature of the announcement and the Irreproducibility of the effect divided the scientific community into believers and skeptics, indicating religious fervor rather than scientific reasoning. Shortly after the Fleischmann-Pons announcement, a program at NRaD investigated anomalous effects in the Pd/D system. The NRaD program investigated the Pd/D system using standard electrochemical techniques to determine conditions for achieving high Pd/D loadings. Metallurgical aspects of the Pd/D system and the effect of additives were also examined. Tritium content in the gas/liquid phases and radiation emissions were monitored during electrolysis. This report summarizes the investigation results.

  18. Development of Pd-Ag Compostie Membrane for Separation of Hydrogen at Elevated Temperature

    SciTech Connect (OSTI)

    Shamsuddin Ilias

    2009-02-28

    Pd-based membrane reactor offers the possibility of combining reaction and separation in a single operation at high temperatures to overcome the equilibrium limitations experienced in conventional reactor configurations. In this project to develop a defect-free and hermally-stable Pd-film on microporous stainless steel (MPSS) support for H2-separation and membrane reactor applications, the electroless plating process was revisited with an aim to improve the membrane morphology. Specifically, this study includes; (a) an improvement f activation step using Pulse Laser Deposition (PLD), (b) development of a novel surfactant induced electroless plating (SIEP) for depositing robust Pd-film on microporous support, and (c) application of Pd-membrane as membrane reactor in steam methanol reforming (SMR) reactions.

  19. Influence of Oxygen and pH on the Selective Oxidation of Ethanol on Pd Catalysts

    SciTech Connect (OSTI)

    Hibbitts, David D.; Neurock, Matthew

    2013-03-01

    The selective oxidation of ethanol on supported Pd is catalytically promoted by the presence of hydroxide species on the Pd surface as well as in solution. These hydroxide intermediates act as Brønsted bases which readily abstract protons from the hydroxyl groups of adsorbed or solution-phase alcohols. The C1AH bond of the resulting alkoxide is subsequently activated on the metal surface via hydride elimination to form acetaldehyde. Surface and solution-phase hydroxide intermediates can also readily react with the acetaldehyde via nucleophilic addition to form a germinal diol intermediate, which subsequently undergoes a second C1AH bond activation on Pd to form acetic acid. The role of O2 is to remove the electrons produced in the oxidation reaction via the oxygen reduction reaction over Pd. The reduction reaction also regenerates the hydroxide intermediates and removes adsorbed hydrogen that is produced during the oxidation.

  20. Enhanced Fe2O3 Reducibility via Surface Modification with Pd...

    Office of Scientific and Technical Information (OSTI)

    The synergistic catalysis in the hydrodeoxygenation of phenolic compounds over a PdFe bimetallic surface has been well established. However, the nature of this synergy is still in ...

  1. Method and Pd/V2 O5 device for H2 detection

    DOE Patents [OSTI]

    Liu, Ping; Tracy, C. Edwin; Pitts, J. Roland; Smith, II, R. Davis; Lee, Se-Hee

    2011-12-27

    Methods and Pd/V.sub.2O.sub.5 devices for hydrogen detection are disclosed. An exemplary method of preparing an improved sensor for chemochromic detection of hydrogen gas over a wide response range exhibits stability during repeated coloring/bleaching cycles upon exposure and removal of hydrogen gas. The method may include providing a substrate. The method may also include depositing a V.sub.20.sub.5 layer that functions as a H.sub.2 insertion host in a Pd/V.sub.20.sub.5 hydrogen sensor to be formed on said substrate. The method may also include depositing a Pd layer onto said V.sub.20.sub.5 layer; said Pd layer functioning as an optical modulator.

  2. Photon energy dependence of photo-induced inverse spin-Hall effect in Pt/GaAs and Pt/Ge

    SciTech Connect (OSTI)

    Isella, Giovanni Bottegoni, Federico; Ferrari, Alberto; Finazzi, Marco; Ciccacci, Franco

    2015-06-08

    We report the photon energy dependence of photo-induced inverse spin Hall effect (ISHE) in Pt/GaAs and Pt/Ge Schottky junctions. The experimental results are compared with a spin drift-diffusion model, which highlights the role played by the different spin lifetime in the two semiconductors, in determining the energy dependence of the ISHE signal detected in the Pt layer. The good qualitative agreement between experiments and modelling indicates that photo-induced ISHE can be used as a tool to characterize spin lifetime in semiconductors.

  3. Temperature, pressure, and size dependence of Pd-H interaction in size selected Pd-Ag and Pd-Cu alloy nanoparticles: In-situ X-ray diffraction studies

    SciTech Connect (OSTI)

    Sengar, Saurabh K.; Mehta, B. R.; Kulriya, P. K.

    2014-03-21

    In this study, in-situ X-ray diffraction has been carried out to investigate the effect of temperature and pressure on hydrogen induced lattice parameter variation in size selected Pd-Ag and Pd-Cu alloy nanoparticles. The nanoparticles of three different mobility equivalent diameters (20, 40, and 60 nm) having a narrow size distribution were prepared by gas phase synthesis method. In the present range of temperature (350 K to 250 K) and pressure (10{sup −4} to 100 millibars), no α (H/Pd ≤ 0.03) ↔ β (H/Pd ≥ 0.54) phase transition is observed. At temperature higher than 300 °C or pressure lower than 25 millibars, there is a large difference in the rate at which lattice constant varies as a function of pressure and temperature. Further, the lattice variation with temperature and pressure is also observed to depend upon the nanoparticle size. At lower temperature or higher pressure, size of the nanoparticle seems to be relatively less important. These results are explained on the basis of the relative dominance of physical absorption and diffusion of H in Pd alloy nanoparticles at different temperature and pressure. In the present study, absence of α ↔ β phase transition points towards the advantage of using Pd-alloy nanoparticles in applications requiring long term and repeated hydrogen cycling.

  4. A comparison of the structure and localized magnetism in Ce{sub 2}PdGa{sub 12} with the heavy fermion CePdGa{sub 6}

    SciTech Connect (OSTI)

    Macaluso, Robin T. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Millican, Jasmine N. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Nakatsuji, Satoru [Department of Physics, Kyoto University, Kyoto, Japan 606-8502 (Japan); Lee, Han-Oh [Department of Physics, University of California, Davis, CA 95616 (United States); Carter, B. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Moreno, Nelson O. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Fisk, Zachary [Department of Physics, University of California, Davis, CA 95616 (United States); Chan, Julia Y. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States)]. E-mail: jchan@lsu.edu

    2005-11-15

    Single crystals of Ce{sub 2}PdGa{sub 12} have been synthesized in Ga flux and characterized by X-ray diffraction. This compound crystallizes in the tetragonal P4/nbm space group, Z=2 with lattice parameters of a=6.1040(2)A and c=15.5490(6)A. It shows strongly anisotropic magnetism and orders antiferromagnetically at T{sub N}{approx}11K. A field-induced metamagnetic transition to the ferromagnetic state is observed below T{sub N}. Structure-property relationships with the related heavy-fermion antiferromagnet CePdGa{sub 6} are discussed.

  5. Structural stability of 1100{degree}C heated Pd/k during absorption cycling in protium

    SciTech Connect (OSTI)

    Fisher, I.A.

    1993-03-12

    Pd/k is a hydride forming packing material which is used in the Thermal Cycling Absorption Process (TCAP). Palladium is supported on kieselguhr to create a packing material which will provide adequate void space to prevent excessive pressure drops and flow restrictions. The use of unsupported palladium would result in blockage of columns and clogging of filters due to the small particle size of unsupported palladium hydride powder. During pilot scale demonstrations, it was noted that the Pd/k packing material had degraded causing severe flow restrictions within the TCAP column. A solution to the problem involved the heating of Pd/k at 1,110{degree}C to strengthen the packing material, and render it more resistant to breakdown. The 1, 100{degree}C heated Pd/k has been shown to be more resistant to mechanical breakdown than the Pd/k prior to heat treatment. Two primary modes of Pd/k particle degradation have been identified: mechanical breakdown caused by particle fluidization and degradation caused by absorption/desorption cycling. Absorption/desorption cycling causes the palladium particles within the packing to expanded and contract upon formation and decomposition of the hydride, respectively. This expansion and contraction causes large localized stresses within the packing material, which if these stresses can not be accommodated within the packing will cause the material to crack and degrade. The purpose of this report is to document the results of the absorption/desorption cycling of 1,100{degree}C heated Pd/k and compare these results to the results obtained from the absorption/desorption cycling of Pd/k which had not been heated at 1, 100{degree}C.

  6. A Study of Groundwater Matrix Effects for the Destruction of Trichloroethylene Using Fe/Pd Nanoaggregates

    SciTech Connect (OSTI)

    meyer, D E; Hampson, Steve; ormsbee, Lindelle; Bhattacharyya, Dibakar

    2008-06-01

    Fe nanoaggregates have been prepared using the sodium borohydride reduction method and post-coated with Pd using aqueous phase electro-depostition. The Fe/Pd particles have been used to examine dechlorination of TCE with regard to matrix effects using materials representative of examine dechlorination of TCE with regard to matrix effects using materials representative of a potential zero-valent metal remediation site surrounding the Paducah Gaseous Diffusion Plant in Paducah, KY.

  7. Pd?Cd11? (0.21???0.51)a partly disordered ?-brass type phase and Pd?.???Cd?.??? -a ?-brass related incommensurate phase in the palladiumcadmium system

    SciTech Connect (OSTI)

    Jana, Partha Pratim; Lidin, Sven

    2013-05-01

    The Cd rich part of the CdPd phase diagram was reassessed by means of synthesis and single crystal and powder X-ray diffraction. The region contains two phases that have been reported to have substantial compositional widths, Cd??Pd? and Cd?Pd. The phase Cd??Pd? that has previously been reported to be a disordered ?-brass crystallizing is space group P4-bar 3m is here shown to crystallize in I4-bar 3m and the mechanism for compositional variation is explained. The phase Pd?Cd has previously been shown to constitute a phase field or a phase bundle of modulated structures and here we determine the structure of a compound Pd?.???Cd?.??? which crystallizes in the orthorhombic superspace group mm(?00)0s0 (F=[(, , 0, 0); (, 0, , 0 ); (0, , , 0 )] with the fundamental cell dimensions a=4.687(2) , b=10.000(1) , c=14.140(2) , q=0.6432(6)a?. - Graphical abstract: The crystal structures of the partly disordered ?-brass type Pd?Cd11? (0.21???0.51) and ?-brass related Pd?.???Cd?.??? in the palladiumcadmium binary system. Highlights: Partly disordered ?-brass type Pd?Cd11? (0.21???0.51) and ?-brass related Pd?.???Cd?.??? have been synthesized. The Pd?Cd11? structure have been described by cluster concept. Incommensurately modulated Pd?.???Cd?.??? have been described by (3+1) D space description. The structure of Pd?.???Cd?.??? has two different chains of atomic subunits, each with their own translational periodicities.

  8. A "roller-wheel" Pt-containing small molecule that outperforms its polymer analogs in organic solar cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    He, Wenhan; Wu, Qin; Livshits, Maksim Y.; Dickie, Diane A.; Yang, Jianzhong; Quinnett, Rachel; Rack, Jeffrey R.; Qin, Yang

    2016-05-23

    A novel Pt-bisacetylide small molecule (Pt-SM) featuring “roller-wheel” geometry was synthesized and characterized. When compared with conventional Pt-containing polymers and small molecules having “dumbbell” shaped structures, Pt-SM displays enhanced crystallinity and intermolecular π–π interactions, as well as favorable panchromatic absorption behaviors. Furthermore, organic solar cells (OSCs) employing Pt-SM achieve power conversion efficiencies (PCEs) up to 5.9%, the highest reported so far for Pt-containing polymers and small molecules.

  9. Isothermal Solid-State Transformation Kinetics Applied to Pd/Cu Alloy Membrane Fabrication

    SciTech Connect (OSTI)

    Pomerantz, Natalie L; Payzant, E Andrew; Ma, Yi Hua

    2010-01-01

    In this work, time-resolved, in situ high-temperature X-ray diffraction (HT-XRD) was used to study the solid-state transformation kinetics of the formation of the fcc Pd/Cu alloy from Pd/Cu bi-layers for the purpose of fabricating sulfur tolerant Pd/Cu membranes for H2 separation. Thin layers of Pd and Cu (total ~15 wt% Cu) were deposited on porous stainless steel (PSS) with the electroless deposition method and annealed in H2 at 500, 550 and 600 C. The kinetics of the annealing process were successfully described by the Avrami nucleation and growth model showing that the annealing process was diffusion controlled and one dimensional. The activation energy for the solid-state transformation was 175 kJ/mol, which was similar to the activation energy of Pd-Cu bulk interdiffusion. Furthermore, the Avrami model was able to successfully describe the changes in permeance and activation energy observed in Pd/Cu alloy membranes during characterization as they were annealed at high temperatures.

  10. Local structure order in Pd78Cu6Si16 liquid

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Yue, G. Q.; Zhang, Y.; Sun, Y.; Shen, B.; Dong, F.; Wang, Z. Y.; Zhang, R. J.; Zheng, Y. X.; Kramer, M. J.; Wang, S. Y.; et al

    2015-02-05

    The short-range order (SRO) in Pd78Cu6Si16 liquid was studied by high energy x-ray diffraction and ab initio molecular dynamics (MD) simulations. The calculated pair correlation functions at different temperatures agree well with the experimental results. The partial pair correlation functions from ab intio MD simulations indicate that Si atoms prefer to be uniformly distributed while Cu atoms tend to aggregate. By performing structure analysis using Honeycutt-Andersen index, Voronoi tessellation, and atomic cluster alignment method, we show that the icosahedron and face-centered cubic SRO increase upon cooling. The dominant SRO is the Pd-centered Pd9Si2 motif, namely the structure of which motifmore » is similar to the structure of Pd-centered clusters in the Pd9Si2 crystal. The study further confirms the existence of trigonal prism capped with three half-octahedra that is reported as a structural unit in Pd-based amorphous alloys. The majority of Cu-centered clusters are icosahedra, suggesting that the presence of Cu is benefit to promote the glass forming ability.« less

  11. Electronic circuits having NiAl and Ni.sub.3 Al substrates

    DOE Patents [OSTI]

    Deevi, Seetharama C.; Sikka, Vinod K.

    1999-01-01

    An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

  12. Effect of gold subsurface layer on the surface activity and segregation in Pt/Au/Pt{sub 3}M (where M = 3d transition metals) alloy catalyst from first-principles

    SciTech Connect (OSTI)

    Kim, Chang-Eun; Lim, Dong-Hee; Jang, Jong Hyun; Kim, Hyoung Juhn; Yoon, Sung Pil; Han, Jonghee; Nam, Suk Woo; Hong, Seong-Ahn; Soon, Aloysius E-mail: hchahm@kist.re.kr; Ham, Hyung Chul E-mail: hchahm@kist.re.kr

    2015-01-21

    The effect of a subsurface hetero layer (thin gold) on the activity and stability of Pt skin surface in Pt{sub 3}M system (M = 3d transition metals) is investigated using the spin-polarized density functional theory calculation. First, we find that the heterometallic interaction between the Pt skin surface and the gold subsurface in Pt/Au/Pt{sub 3}M system can significantly modify the electronic structure of the Pt skin surface. In particular, the local density of states projected onto the d states of Pt skin surface near the Fermi level is drastically decreased compared to the Pt/Pt/Pt{sub 3}M case, leading to the reduction of the oxygen binding strength of the Pt skin surface. This modification is related to the increase of surface charge polarization of outmost Pt skin atoms by the electron transfer from the gold subsurface atoms. Furthermore, a subsurface gold layer is found to cast the energetic barrier to the segregation loss of metal atoms from the bulk (inside) region, which can enhance the durability of Pt{sub 3}M based catalytic system in oxygen reduction condition at fuel cell devices. This study highlights that a gold subsurface hetero layer can provide an additional mean to tune the surface activity toward oxygen species and in turn the oxygen reduction reaction, where the utilization of geometric strain already reaches its practical limit.

  13. Formation, characterization and reactivity of adsorbed oxygen on BaO/Pt(111)

    SciTech Connect (OSTI)

    Mudiyanselage, Kumudu; Mei, Donghai; Yi, Cheol-Woo; Weaver, Jason F.; Szanyi, Janos

    2010-12-02

    The formation of adsorbed O (Oad) species and their reactivities in CO oxidation on BaO/Pt(111) (at two BaO coverages) were studied with temperature programmed desorption (TPD), infrared reflection absorption (IRA) and X-ray photoelectron (XP) spectroscopies. In neither of these two systems was the Pt(111) surface completely covered with BaO. On the system with lower BaO coverage (~45 % of the Pt(111) surface is covered by BaO), two different Oad species form following the adsorption of O2 at 300 K: O adsorbed on BaO-free Pt(111) sites (OPt) and at the Pt-BaO interface (Oint). On the system with higher BaO coverage (~60 % of the Pt(111) surface is covered by BaO), two types of Oint are seen at the Pt-BaO interface. The desorption of OPt from the BaO-free portion of the Pt(111) surface gives an O2 desorption peak with a maximum desorption rate at ~690 K. Migration of Oint to the Pt(111) sites and their recombinative desorption give two explosive desorption features at ~760 and ~790 K in the TPD spectrum. The reactivities of these Oad species with CO to form CO2 follow their sequence of desorption; i.e., the OPt associated with the BaO-free Pt(111) surface, which desorbs at 690 K, reacts first with CO, followed by the Oint species at the Pt-BaO interface (first the one that desorbs at ~760 K and finally the one that is bound the most strongly to the interface, and desorbs at ~790 K). This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  14. Photosensitivity of the Ni-A state of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F with visible light

    SciTech Connect (OSTI)

    Osuka, Hisao; Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5, Takayama-cho, Ikoma-shi, Nara 630-0192 ; Shomura, Yasuhito; Komori, Hirofumi; Shibata, Naoki; Nagao, Satoshi; Higuchi, Yoshiki; CREST, JST, Gobancho, Chiyoda-ku, Tokyo 102-0076 ; Hirota, Shun; CREST, JST, Gobancho, Chiyoda-ku, Tokyo 102-0076

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer Ni-A state of [NiFe] hydrogenase showed light sensitivity. Black-Right-Pointing-Pointer New FT-IR bands were observed with light irradiation of the Ni-A state. Black-Right-Pointing-Pointer EPR g-values of the Ni-A state shifted upon light irradiation. Black-Right-Pointing-Pointer The light-induced state converted back to the Ni-A state under the dark condition. -- Abstract: [NiFe] hydrogenase catalyzes reversible oxidation of molecular hydrogen. Its active site is constructed of a hetero dinuclear Ni-Fe complex, and the oxidation state of the Ni ion changes according to the redox state of the enzyme. We found that the Ni-A state (an inactive unready, oxidized state) of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F (DvMF) is light sensitive and forms a new state (Ni-AL) with irradiation of visible light. The Fourier transform infrared (FT-IR) bands at 1956, 2084 and 2094 cm{sup -1} of the Ni-A state shifted to 1971, 2086 and 2098 cm{sup -1} in the Ni-AL state. The g-values of g{sub x} = 2.30, g{sub y} = 2.23 and g{sub z} = 2.01 for the signals in the electron paramagnetic resonance (EPR) spectrum of the Ni-A state at room temperature varied for -0.009, +0.012 and +0.010, respectively, upon light irradiation. The light-induced Ni-AL state converted back immediately to the Ni-A state under dark condition at room temperature. These results show that the coordination structure of the Fe site of the Ni-A state of [NiFe] hydrogenase is perturbed significantly by light irradiation with relatively small coordination change at the Ni site.

  15. Shape coexistence in the neutron-deficient Pt isotopes in the configuration-mixed IBM

    SciTech Connect (OSTI)

    Vargas, Carlos E.; Campuzano, Cuauhtemoc; Morales, Irving O.; Frank, Alejandro; Van Isacker, Piet

    2008-05-12

    The matrix-coherent state approach in the IBM with configuration mixing is used to describe the geometry of neutron-deficient Pt isotopes. Employing a parameter set for all isotopes determined previously, it is found that the lowest minimum goes from spherical to oblate and finally acquires a prolate shape when approaching the mid-shell Pt isotopes.

  16. Effect of reductive treatments on Pt behavior and NOx storage in lean NOx trap catalysts

    SciTech Connect (OSTI)

    Wang, Xianqin; Kim, Do Heui; Kwak, Ja Hun; Wang, Chong M.; Szanyi, Janos; Peden, Charles HF

    2011-10-01

    Lean NOx trap (LNT) catalysts represent a promising approach to meet increasingly stringent NOx emission regulations on diesel and other lean-burn engines. Pt material properties, including dispersion and particle size, are known to be important factors in determining NOx uptake performance, since Pt provides active sites for NO oxidation to NO2 necessary for storing NOx as nitrates, and for the reduction of nitrates to N2. In this work, the physicochemical properties of Pt in Pt-BaO/Al2O3 LNT catalysts, such as the Pt accessible surface area and particle size, were investigated by using various tools, such as irreversible volumetric H2 chemisorption, high resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD), following successive reductive treatments at elevated temperatures. NOx uptake activities were also measured to establish a relationship between the properties of Pt and NOx storage following identical high-temperature reductive treatments. We find that the reductive treatments of Pt-BaO/Al2O3 lean NOx trap catalysts at temperatures up to 500 ºC promote a significant increase in NOx uptake explained, in part, by an induced close interaction between Pt and BaO phases in the catalyst, thus enabling facilitation of the NOx storage process.

  17. 37pt.2PerformanceBasedServiceAcquisition.pdf | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    7pt.2PerformanceBasedServiceAcquisition.pdf 37pt.2PerformanceBasedServiceAcquisition.pdf (1022.17 KB) More Documents & Publications Acquisitions___Communications.pdf Acquisition Guide Chapter 7.1 - Acquisition Planning One Acquisition Solution for Integrated Services (OASIS) - Brad DeMers, General Services Administration (GSA)

  18. Temperature evolution of electromotive force from Pt on yttrium-iron-garnet under ferromagnetic resonance

    SciTech Connect (OSTI)

    Ohshima, Ryo; Emoto, Hiroyuki; Shinjo, Teruya; Ando, Yuichiro; Shiraishi, Masashi

    2015-05-07

    Temperature evolution of electromotive force from Pt due to the inverse spin Hall effect is studied. Pure spin current is injected from yttrium-iron-garnet by using spin pumping technique. The electromotive force from the Pt monotonically decreases with decreasing temperature, and it is showed that there is a deviation between the measured and the calculated electromotive forces.

  19. Ordinary versus PT-symmetric Φ³ quantum field theory

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bender, Carl M.; Branchina, Vincenzo; Messina, Emanuele

    2012-04-02

    A quantum-mechanical theory is PT-symmetric if it is described by a Hamiltonian that commutes with PT, where the operator P performs space reflection and the operator T performs time reversal. A PT-symmetric Hamiltonian often has a parametric region of unbroken PT symmetry in which the energy eigenvalues are all real. There may also be a region of broken PT symmetry in which some of the eigenvalues are complex. These regions are separated by a phase transition that has been repeatedly observed in laboratory experiments. This paper focuses on the properties of a PT-symmetric igΦ³ quantum field theory. This quantum fieldmore » theory is the analog of the PT-symmetric quantum-mechanical theory described by the Hamiltonian H=p²+ix³, whose eigenvalues have been rigorously shown to be all real. This paper compares the renormalization group properties of a conventional Hermitian gΦ³ quantum field theory with those of the PT-symmetric igΦ³ quantum field theory. It is shown that while the conventional gΦ³ theory in d=6 dimensions is asymptotically free, the igΦ³ theory is like a gΦ⁴ theory in d=4 dimensions; it is energetically stable, perturbatively renormalizable, and trivial.« less

  20. Thermal stability and oxygen-loss characteristics of Pt(O) films prepared by reactive sputtering

    SciTech Connect (OSTI)

    Saenger, K.L.; Cabral, C. Jr.; Lavoie, C.; Rossnagel, S.M.

    1999-12-01

    Pt(O) films having compositions ranging from pure Pt to amorphous platinum oxide a-PtO{sub x} (x{approximately}1.4) were prepared by reactive sputtering and examined during and after heating to temperatures used for deposition and processing of high-epsilon (HE) and ferroelectric (FE) materials (400{endash}650&hthinsp;{degree}C). A two stage decomposition process was observed for a-PtO{sub x} (x{approximately}1.4) films heated in N{sub 2}, with the first stage of decomposition beginning at temperatures well below 400&hthinsp;{degree}C. In an O{sub 2} ambient, decomposition was accompanied by formation of a crystalline Pt{sub 3}O{sub 4} phase prior to complete decomposition to metallic Pt. However, the relatively slow rate of oxygen loss from a-PtO{sub x} suggests that significant amounts of oxygen should remain in Pt(O) electrodes after HE/FE layer deposition. {copyright} {ital 1999 American Institute of Physics.}

  1. Ordinary versus PT-symmetric Φ³ quantum field theory

    SciTech Connect (OSTI)

    Bender, Carl M.; Branchina, Vincenzo; Messina, Emanuele

    2012-04-02

    A quantum-mechanical theory is PT-symmetric if it is described by a Hamiltonian that commutes with PT, where the operator P performs space reflection and the operator T performs time reversal. A PT-symmetric Hamiltonian often has a parametric region of unbroken PT symmetry in which the energy eigenvalues are all real. There may also be a region of broken PT symmetry in which some of the eigenvalues are complex. These regions are separated by a phase transition that has been repeatedly observed in laboratory experiments. This paper focuses on the properties of a PT-symmetric igΦ³ quantum field theory. This quantum field theory is the analog of the PT-symmetric quantum-mechanical theory described by the Hamiltonian H=p²+ix³, whose eigenvalues have been rigorously shown to be all real. This paper compares the renormalization group properties of a conventional Hermitian gΦ³ quantum field theory with those of the PT-symmetric igΦ³ quantum field theory. It is shown that while the conventional gΦ³ theory in d=6 dimensions is asymptotically free, the igΦ³ theory is like a gΦ⁴ theory in d=4 dimensions; it is energetically stable, perturbatively renormalizable, and trivial.

  2. Consistent Data Assimilation of Isotopes: 242Pu and 105Pd

    SciTech Connect (OSTI)

    G. Palmiotti; H. Hiruta; M. Salvatores

    2012-09-01

    In this annual report we illustrate the methodology of the consistent data assimilation that allows to use the information coming from integral experiments for improving the basic nuclear parameters used in cross section evaluation. A series of integral experiments are analyzed using the EMPIRE evaluated files for 242Pu and 105Pd. In particular irradiation experiments (PROFIL-1 and -2, TRAPU-1, -2 and -3) provide information about capture cross sections, and a critical configuration, COSMO, where fission spectral indexes were measured, provides information about fission cross section. The observed discrepancies between calculated and experimental results are used in conjunction with the computed sensitivity coefficients and covariance matrix for nuclear parameters in a consistent data assimilation. The results obtained by the consistent data assimilation indicate that not so large modifications on some key identified nuclear parameters allow to obtain reasonable C/E. However, for some parameters such variations are outside the range of 1 s of their initial standard deviation. This can indicate a possible conflict between differential measurements (used to calculate the initial standard deviations) and the integral measurements used in the statistical data adjustment. Moreover, an inconsistency between the C/E of two sets of irradiation experiments (PROFIL and TRAPU) is observed for 242Pu. This is the end of this project funded by the Nuclear Physics Program of the DOE Office of Science. We can indicate that a proof of principle has been demonstrated for a few isotopes for this innovative methodology. However, we are still far from having explored all the possibilities and made this methodology to be considered proved and robust. In particular many issues are worth further investigation: • Non-linear effects • Flexibility of nuclear parameters in describing cross sections • Multi-isotope consistent assimilation • Consistency between differential and integral

  3. Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lee, H. K.; Barsukov, I.; Swartz, A. G.; Kim, B.; Yang, L.; Hwang, H. Y.; Krivorotov, I. N.

    2016-05-16

    In this paper, we report ferromagnetic resonance measurements of magnetic anisotropy and damping in epitaxial La0.7Sr0.3MnO3 (LSMO) and Pt capped LSMO thin films on SrTiO3 (001) substrates. The measurements reveal large negative perpendicular magnetic anisotropy and a weaker uniaxial in-plane anisotropy that are unaffected by the Pt cap. The Gilbert damping of the bare LSMO films is found to be low α = 1.9(1) × 10-3, and two-magnon scattering is determined to be significant and strongly anisotropic. The Pt cap increases the damping by 50% due to spin pumping, which is also directly detected via inverse spin Hall effect inmore » Pt. Our research demonstrates efficient spin transport across the Pt/LSMO interface.« less

  4. Determination of the Pt spin diffusion length by spin-pumping and spin Hall effect

    SciTech Connect (OSTI)

    Zhang, Wei; Pearson, John E.; Hoffmann, Axel; Vlaminck, Vincent; Divan, Ralu; Bader, Samuel D.

    2013-12-09

    The spin diffusion length of Pt at room temperature and at 8 K is experimentally determined via spin pumping and spin Hall effect in permalloy/Pt bilayers. Voltages generated during excitation of ferromagnetic resonance from the inverse spin Hall effect and anisotropic magnetoresistance effect were investigated with a broadband approach. Varying the Pt layer thickness gives rise to an evolution of the voltage line shape due to the superposition of the above two effects. By studying the ratio of the two voltage components with the Pt layer thickness, the spin diffusion length of Pt can be directly extracted. We obtain a spin diffusion length of ∼1.2 nm at room temperature and ∼1.6 nm at 8 K.

  5. Catalytic decomposition of Ba(NO3)2 on Pt(111)

    SciTech Connect (OSTI)

    Mudiyanselage, Kumudu; Weaver, Jason F.; Szanyi, Janos

    2011-04-07

    The decomposition of Ba(NO3)2 formed on BaO/Pt(111) (Pt(111) surface is partially covered by BaO) in the presence of CO was studied using temperature programmed desorption (TPD), infrared reflection absorption (IRA) and X-ray photoelectron (XP) spectroscopies. The exposure of BaO/Pt(111) to elevated NO2 pressure (1.0×10-4 Torr) at 450 K leads to the formation of Ba(NO3)2, chemisorbed O (OPt) and Pt-oxide-like domains. During TPD, the Ba(NO3)2 begins to thermally decompose near 490 K, releasing NO and NO2 with the maximum NOx desorption rate seen at 605 K. The OPt species formed following the exposure of BaO/Pt(111) to NO2 react with CO to release CO2 at 450 K. The consumption of OPt during CO oxidation initiates the migration of O from the Pt-oxide-like domains to the chemisorbed phase, where the CO oxidation reaction occurs. Therefore, the removal of OPt by CO leads to the reduction of oxidized Pt, and to the formation of metallic Pt(111) domains, where, subsequently, catalytic decomposition of Ba(NO3)2 can take place. The Pt-catalyzed decomposition of Ba(NO3)2 occurs readily at 450 K, a temperature much lower than the onset of the decomposition temperature of Ba(NO3)2 in the presence of oxidized Pt. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  6. Synthesis and characterization of model MgO supported catalyst with Pt-Mo interactions.

    SciTech Connect (OSTI)

    Alexeev, O.; Kawi, S.; Gates, B.C. [Univ. of California, Davis, CA (United States)] [Univ. of California, Davis, CA (United States); Shelef, M. [Ford Motor Co., Dearborn, MI (United States)] [Ford Motor Co., Dearborn, MI (United States)

    1996-01-04

    MgO supported platinum and platinum-molybdenum catalysts were prepared from organometallic precursors and charaterized structurally to determine how the nature of the bimetallic precursors and the treatment conditions affected the interaction between the two metals. Samples were prepared from [PtCl{sub 2}(PhCN){sub 2}], [PtCl{sub 2}(PhCN){sub 2}] + [Mo(CO){sub 6}], and [C@Pt[Mo(CO){sub 3}(C{sub 5}H{sub 5})]{sub 2}(PhCN){sub 2}] BC@ characterized by infrared and extended X-ray absorption fine structure (EXAFS) spectroscopies, tranmission electron microscopy, and chemisorption of H{sub 2}, CO, and O{sub 2}. The samples were treated in H{sub 2} at 400{degree}C prior to most of the characterizatons. Incorporation of Mo reduced the chemisorption of CO and of H{sub 2}. EXAFS spectra measured at the Pt L{sub III} edge and at the Mo K edge showed substantial Pt-Mo contributions with a Pt-Mo cordination number of about 2 and an average distance of 2.63 A for the sample prepared from [C@Pt[Mo(CO){sub 3}(C{sub 5}H{sub 5})]{sub 2}(PhCN){sub 2}] BC@. In constract, no significant Pt-Mo contribution was observed for the sample prepared from [PtCl{sub 2}(PhCN){sub 2}]+ [Mo(CO){sub 6}]. Electron micrographs and EXAFS results show that interaction between Pt and Mo ions in the former sample helped to maintain the platinum in a highly dispersed form, with supported platinum clusters being smaller than about 10 A. 53 refs., 9 figs., 9 tabs.

  7. Effects of Ionomer Morphology on Oxygen Reduction on Pt

    SciTech Connect (OSTI)

    Chlistunoff, Jerzy; Pivovar, Bryan

    2015-05-21

    In this paper, the oxygen reduction reaction (ORR) at the interface between platinum and Nafion 1100 equivalent weight was studied as a function of temperature (20–80 °C), humidity (10–100%), scan rate, the manner in which Nafion film was deposited, and the state of the Pt surface using ultramicroelectrodes employing cyclic voltammetry and chronoamperometry. ORR on smooth electrodes was strongly inhibited under specific conditions dependent on temperature, humidity, and scan rate. From the data presented, we postulate that dynamic changes in the molecular structure of the ionomer at the platinum interface result in differences in ORR voltammetry for films prepared and equilibrated under different conditions. The lack of similar changes for rough, platinized electrodes has been attributed to differences in initial ionomer structure and a higher energy barrier for ionomer restructuring. Finally, these model system studies yield insight into the ionomer-catalyst interface of particular interest for polymer electrolyte fuel cells.

  8. Study of the I-V characteristics of nanostructured Pd films on a Si substrate after vacuum annealing

    SciTech Connect (OSTI)

    Tomilin, S. V., E-mail: tomilin_znu@mail.ru; Yanovsky, A. S.; Tomilina, O. A.; Mikaelyan, G. R. [Zaporozhye National University, Department of Semiconductor Physics (Ukraine)

    2013-06-15

    The I-V characteristics of nanostructured Pd films on a Si substrate are investigated. The nanostructures (nanoislands) are formed by the vacuum annealing of continuous ultrathin Pd films sputtered onto a substrate. The shape of the I-V characteristics of the investigated Si substrate-Pd film system is shown to be heavily dependent on the degree of film nanostructuring. The surface morphology of the films is studied using scanning electron microscopy.

  9. Excited states in {sup 115}Pd populated in the {beta}{sup -} decay of {sup 115}Rh

    SciTech Connect (OSTI)

    Kurpeta, J.; Plochocki, A. [Faculty of Physics, University of Warsaw, ul. Hoza 69, PL-00-681 Warsaw (Poland); Urban, W. [Faculty of Physics, University of Warsaw, ul. Hoza 69, PL-00-681 Warsaw (Poland); Institut Laue-Langevin, 6 rue J. Horowitz, F-38042 Grenoble (France); Rissanen, J.; Eronen, T.; Hakala, J.; Jokinen, A.; Kankainen, A.; Karvonen, P.; Moore, I. D.; Penttilae, H.; Saastamoinen, A.; Weber, C.; Aeystoe, J. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40351, Jyvaeskylae (Finland); Elomaa, V.-V. [Turku PET Centre, Accelerator Laboratory, Abo Akademi University, FIN-20500 Turku (Finland); Rahaman, S. [Physics Division, P-23, Mail Stop H803, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Sonoda, T. [Nishina Center for Accelerator Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Szerypo, J. [Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Am Coulombwall 1, D-85748 Garching (Germany)

    2010-08-15

    Excited states in {sup 115}Pd, populated following the {beta}{sup -} decay of {sup 115}Rh have been studied by means of {gamma} spectroscopy after the Penning-trap station at the IGISOL facility, University of Jyvaeskylae. The 1/2{sup +} spin and parity assignment of the ground state of {sup 115}Pd, confirmed in this work, may indicate a transition to an oblate shape in Pd isotopes at high neutron number.

  10. Dosimetric comparison of four new design {sup 103}Pd brachytherapy sources: Optimal design using silver and copper rod cores

    SciTech Connect (OSTI)

    Hosseini, S. Hamed; Sadeghi, Mahdi; Ataeinia, Vahideh

    2009-07-15

    Four new brachytherapy sources, IRA1-{sup 103}Pd, IRA2-{sup 103}Pd, IRA3-{sup 103}Pd, and IRA4-{sup 103}Pd, have been developed at Agricultural, Medical, and Industrial Research School and are designed for permanent implant application. With the goal of determining an optimal design for a {sup 103}Pd source, this article compares the dosimetric properties of these sources with reference to the authors' earlier IRA-{sup 103}Pd source. The four new sources differ in end cap configuration and thickness and in the core material, silver or copper, that carries the adsorbed {sup 103}Pd. Dosimetric data derived from the authors' Monte Carlo simulation results are reported in accordance with the updated AAPM Task Group No. 43 report (TG-43U1). For each source, the authors obtained detailed results for the dose rate constant {Lambda}, the radial dose function g(r), the anisotropy function F(r,{theta}), and the anisotropy factor {phi}{sub an}(r). In this study, the optimal source IRA3-{sup 103}Pd provides the most isotropic dose distribution in water with the dose rate constant of 0.678({+-}0.1%) cGy h{sup -1} U{sup -1}. The IRA3-{sup 103}Pd design has a silver rod core combined with thin-wall, concave end caps. Finally, the authors compared the results for their optimal source with published results for those of other source manufacturers.

  11. Aqueous Co-precipitation of Pd-doped Cerium Oxide Nanoparticles: Chemistry Structure and Particle Growth

    SciTech Connect (OSTI)

    Liang H.; Zhang L.; Raitano J.M.; He G.; Akey A.J.; Herman I.P.; Chan S.-W.

    2012-01-01

    Nanoparticles of palladium-doped cerium oxide (Pd-CeO{sub 2}) have been prepared by aqueous co-precipitation resulting in a single phase cubic structure after calcination according to X-ray diffraction (XRD). Inhomogeneous strain, calculated using the Williamson-Hall method, was found to increase with palladium content, and the lattice contracts slightly, relative to nano-cerium oxide, as palladium content is increased. Moreover, high resolution transmission electron microscopy reveals some instances of defective microstructure. These factors combined imply that palladium is in solid solution with CeO{sub 2} in these nanoparticles, but palladium (II) oxide (PdO) peaks in the Raman spectra indicate that solid solution formation is partial and that highly dispersed PdO is present as well as the solid solution. Nevertheless, the addition of palladium to the CeO{sub 2} lattice inhibits the growth of the 6% Pd-CeO{sub 2} particles compared to pure CeO{sub 2} between 600 and 850 C. Activation energies for grain growth of 54 {+-} 7 and 79 {+-} 8 kJ/mol were determined for 6% Pd-CeO{sub 2} and pure CeO{sub 2}, respectively, along with pre-exponential Arrhenius factors of 10 for the doped sample and 600 for pure cerium oxide.

  12. Pd menbrane having improved H.sub.2-permeance, and method of making

    DOE Patents [OSTI]

    Vanderspurt, Thomas Henry; She, Ying; Dardas, Zissis; Walker, Craig; MacLeod, James D.

    2011-12-06

    An H.sub.2-permeable membrane system (117) comprises an electroless-deposited plating (115) of Pd or Pd alloy on a porous support (110, 110'). The Pd plating comprises face-centered cubic crystals cumulatively having a morphology of hexagonal platelets. The permeability to H.sub.2 of the membrane plating (115) on the porous support is significantly enhanced, being at least greater than about 1.3.times.10.sup.-8 molm.sup.-1s.sup.-Pa.sup.-0.5 at 350.degree. C., and even greater than about 3.4.times.10.sup.-8 molm.sup.-1s.sup.-1Pa.sup.-0.5. The porous support (110, 110') may be stainless steel (1100 and include a thin ceramic interlayer (110') on which the Pd is plated. The method of providing the electroless-deposited plating includes preheating a Pd electroless plating solution to near a plating temperature substantially greater than room temperature, e.g. 60.degree. C., prior to plating.

  13. Glycerol Hydrogenolysis on Carbon-Supported PtRu and AuRu Bimetallic Catalysts

    SciTech Connect (OSTI)

    Maris,E.; Ketchie, W.; Murayama, M.; Davis, R.

    2007-01-01

    Bimetallic PtRu and AuRu catalysts were prepared by a surface redox method in which Pt or Au was deposited onto the surface of carbon-supported Ru nanoparticles with an average diameter of 2-3 nm. Characterization by H2 chemisorption, analytical TEM, and X-ray absorption spectroscopy at the Ru K-edge, Pt LIII-edge, and Au LIII-edge confirmed that Pt and Au were successfully deposited onto Ru without disrupting the Ru particles. Depression of the ethane hydrogenolysis rate over Ru after addition of Au provided further evidence of successful deposition. The bimetallic particles were subsequently evaluated in the aqueous-phase hydrogenolysis of glycerol at 473 K and 40 bar H2 at neutral and elevated pH. Although monometallic Pt and Ru exhibited different activities and selectivities to products, the bimetallic PtRu catalyst functioned more like Ru. A similar result was obtained for the AuRu bimetallic catalyst. The PtRu catalyst appeared to be stable under the aqueous-phase reaction conditions, whereas the AuRu catalyst was altered by the harsh conditions. Gold appeared to migrate off the Ru and agglomerate on the carbon during the reaction in liquid water.

  14. Enhancement of oxygen reduction reaction activities by Pt nanoclusters decorated on ordered mesoporous porphyrinic carbons

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sun-Mi Hwang; Choi, YongMan; Kim, Min Gyu; Sohn, Young-Jun; Cheon, Jae Yeong; Joo, Sang Hoon; Yim, Sung-Dae; Kuttiyiel, Kurian A.; Sasaki, Kotaro; Adzic, Radoslav R.; et al

    2016-03-08

    The high cost of Pt-based membrane electrode assemblies (MEAs) is a critical hurdle for the commercialization of polymer electrolyte fuel cells (PEFCs). Recently, non-precious metal-based catalysts (NPMCs) have demonstrated much enhanced activity but their oxygen reduction reaction (ORR) activity is still inferior to that of Pt-based catalysts resulting in a much thicker electrode in the MEA. For the reduction of mass transport and ohmic overpotential we adopted a new concept of catalyst that combines an ultra-low amount of Pt nanoclusters with metal–nitrogen (M–Nx) doped ordered mesoporous porphyrinic carbon (FeCo–OMPC(L)). The 5 wt% Pt/FeCo–OMPC(L) showed a 2-fold enhancement in activities comparedmore » to a higher loading of Pt. Our experimental results supported by first-principles calculations indicate that a trace amount of Pt nanoclusters on FeCo–OMPC(L) significantly enhances the ORR activity due to their electronic effect as well as geometric effect from the reduced active sites. Finally, in terms of fuel cell commercialization, this class of catalysts is a promising candidate due to the limited use of Pt in the MEA.« less

  15. Microstructure investigations of hcp phase CoPt thin films with high coercivity

    SciTech Connect (OSTI)

    Yang, Y.; Varghese, B.; Tan, H. K.; Wong, S. K.; Piramanayagam, S. N.

    2014-02-28

    CoPt films have been grown in the past with a high anisotropy in L1{sub 1} or L1{sub 0} phase, and a high coercivity is observed only in L1{sub 0} CoPt films. Recently, we have grown CoPt films which exhibited a high coercivity without exhibiting an ordered phase. In this study, high resolution transmission electron microscopy (HRTEM) investigations have been carried out to understand the strong thickness and deposition pressure dependent magnetic properties. HRTEM studies revealed the formation of an initial growth layer in a metastable hexagonal (hcp) CoPt with high anisotropy. This phase is believed to be aided by the heteroepitaxial growth on Ru as well as the formation of Ru-doped CoPt phase. As the films grew thicker, transformation from hcp phase to an energetically favourable face-centered cubic (fcc) phase was observed. Stacking faults were found predominantly at the hcp-fcc transformation region of the CoPt film. The higher coercivity of thinner CoPt film is attributed to relatively less fcc fraction, less stacking faults, and to the isolated grain structure of these films compared to the thicker films.

  16. Isonitrile radionuclide complexes for labelling and imaging agents

    DOE Patents [OSTI]

    Jones, Alun G.; Davison, Alan; Abrams, Michael J.

    1984-06-04

    A coordination complex of an isonitrile ligand and radionuclide such as Tc, Ru, Co, Pt, Fe, Os, Ir, W, Re, Cr, Mo, Mn, Ni, Rh, Pd, Nb and Ta, is useful as a diagnostic agent for labelling liposomes or vesicles, and selected living cells containing lipid membranes, such as blood clots, myocardial tissue, gall bladder tissue, etc.

  17. EBSD study on crystallographic texture and microstructure development of cold-rolled FePd alloy

    SciTech Connect (OSTI)

    Lin, Hung-Pin; Ng, Tin-San; Kuo, Jui-Chao; Chen, Yen-Chun; Chen, Chun-Liang; Ding, Shi-Xuan

    2014-07-01

    The crystallographic texture and microstructure of FePd alloy after cold-rolling deformation were investigated using electron backscatter diffraction. The major orientations of twin copper and copper after 50% thickness reduction were observed in face-centered cubic-disordered FePd alloy, whereas the main orientation was obtained from brass type after 90% cold rolling. Increase in cold rolling resulted in the change of preferred orientation from copper to brass. Decrease in orientation intensity of copper also increased that of Goss and brass. - Highlights: • The evolution of texture and microstructure in FePd alloy was investigated after cold rolling using EBSD. • Increasing in reduction leads to the change of texture from Copper-type to Brass-type. • The reduction of Copper orientation results in increasing in Goss and Brass orientations.

  18. Influence of Ni on Martensitic Phase Transformations in NiTi Shape Memory Alloys

    SciTech Connect (OSTI)

    Frenzel, J.; George, Easo P; Dlouhy, A.; Somsen, Ch.; Wagner, M. F.-X; Eggeler, G.

    2010-01-01

    High-precision data on phase transformation temperatures in NiTi, including numerical expressions for the effect of Ni on M{sub S}, M{sub F}, A{sub S}, A{sub F} and T{sub 0}, are obtained, and the reasons for the large experimental scatter observed in previous studies are discussed. Clear experimental evidence is provided confirming the predictions of Tang et al. 1999 regarding deviations from a linear relation between the thermodynamic equilibrium temperature and Ni concentration. In addition to affecting the phase transition temperatures, increasing Ni contents are found to decrease the width of thermal hysteresis and the heat of transformation. These findings are rationalized on the basis of the crystallographic data of Prokoshkin et al. 2004 and the theory of Ball and James. The results show that it is important to document carefully the details of the arc-melting procedure used to make shape memory alloys and that, if the effects of processing are properly accounted for, precise values for the Ni concentration of the NiTi matrix can be obtained.

  19. Simple interpretation of shape evolution in Pt isotopes without intruder states

    SciTech Connect (OSTI)

    McCutchan, E.A.; Casten, R.F.; Zamfir, N.V.

    2005-06-01

    The most commonly accepted interpretation of the light Pt isotopes invokes the coexistence and mixing with proton intruder states from above the Z = 82 shell gap. Using an alternative description, interacting boson model (IBA) calculations are performed for the Pt isotopes with a simple, single configuration, two-parameter Hamiltonian. Excellent agreement is obtained for energies and electromagnetic transition strengths over the entire isotopic chain, spanning a wide variety of structures, and suggesting that these nuclei can be described more simply without the introduction of an intruder configuration. The Pt nuclei close to midshell are found to lie close to a region of phase/shape coexistence.

  20. Multiband semimetallic electronic structure of superconducting Ta2PdSe5

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Singh, David Joseph

    2015-04-24

    We report the electronic structure and related properties of the superconductor Ta2PdSe5 as determined from density functional calculations. The Fermi surface has two disconnected sheets, both derived from bands of primarily chalcogenide p states. These are a corrugated hole cylinder and a heavier complex shaped electron sheet. The sheets contain 0.048 holes and a compensating number of electrons per formula unit, making the material a semimetallic superconductor. The results support the presence of two band superconductivity, although a discrepancy in the specific heat is noted. This discrepancy is discussed as a possible consequence of Pd deficiency in samples.

  1. Tuning electron-electron correlation in noncentrosymmetric superconductor BiPd

    SciTech Connect (OSTI)

    Joshi, Bhanu Thamizhavel, A. Ramakrishnan, S.

    2014-04-24

    In this work, we have successfully tuned the electron-electron correlation in new noncentrosymmertic superconductor (NCS) BiPd via Pb substitution on one of the inequivalent Bi sites present in BiPd and simultaneously keeping the parent noncentrosymmetric crystal structure intact. Heat capacity data is suggesting a fourfold increase in density of states at Fermi level via Pb substitution while superconducting transition temperature has been suppressed. This work will clearly open up a rare chance to study the effect of electron–electron correlation via selective tuning of DOS at Fermi level in NCS.

  2. Temperature-dependent H{sub 2} gas-sensing properties of fabricated Pd nanowires using highly oriented pyrolytic graphite

    SciTech Connect (OSTI)

    Sennik, Erdem; Kilinc, Necmettin; Oeztuerk, Zafer Ziya

    2010-09-15

    Horizontal palladium (Pd) nanowires and Pd nanoparticles were successfully fabricated directly on highly oriented pyrolytic graphite depending on the electrodeposition time using palladium nitrate [Pd(NO{sub 2}){sub 3}] solution at room temperature, and the temperature-dependent hydrogen (H{sub 2}) sensing properties of these structures were investigated in the concentration range of 50-5000 ppm. Pd nanowires and Pd nanoparticles were fabricated on a graphite surface by applying triple-pulsed potential with varying the electrodeposition time from 400 to 600 s. The fabricated Pd nanowires were characterized by scanning electron microscopy and energy-dispersive x-ray spectroscopy. It was found that the nanowire arrays were continuous, parallel to each other and ordered after an electrodeposition time of 600 s. The diameters of the Pd nanowires and Pd nanoparticles are observed in the range of 70-180 nm. The H{sub 2} sensing properties of these structures were determined with variation in resistance measurements. It was observed that the limit of detection is lower than 50 ppm H{sub 2}, the sensor response was approximately 2% for 1000 ppm H{sub 2} at room temperature, and the sensor response was decreased with increasing temperature.

  3. Hydrodechlorination of 1,2-Dichloroethane Catalyzedby Dendrimer-Derived Pt-Cu/SiO2 Catalysts

    SciTech Connect (OSTI)

    Xie, Hong; Howe, Jane Y; Schwartz, Viviane; Monnier, J. R.; Williams, Christopher T.; Ploehn, Harry J.

    2008-01-01

    Dendrimer-metal-nanocomposites (DMNs) were used as precursors to prepare SiO2 supported monometallic Pt, Cu and bimetallic Pt-Cu catalysts with Pt/Cu atomic ratios of 1:1 (Pt50Cu50) and 1:3 (Pt25Cu75). After impregnation of these DMNs onto the support, the catalysts were thermally treated and activated following an optimized protocol. Scanning transmission electron microscopy (STEM) shows that the metal nanoparticles in dendrimer-derived SiO2-supported catalysts are smaller and have a more narrow size distribution than those in conventional catalysts prepared using corresponding metal salts via the wet impregnation method. Slow deactivation was observed for hydrodechlorination of 1,2-dichloroethane over monometallic Cu catalysts, which showed an activity about one to two orders of magnitude lower than that of the Pt-containing catalysts. Hydrodechlorination of 1,2-dichloroethane over Pt and Pt50Cu50 catalysts mainly produces ethane and the selectivity towards ethane increases with temperature. For Pt25Cu75 catalyst, the selectivity towards ethane decreases in favor of ethylene. The overall activity decreases with increasing Cu loading in the catalysts. Activity based on surface Pt sites suggests the formation of bi-functional surfaces in Pt25Cu75 catalyst favoring C-Cl bond scission on Cu sites and hydrogenation of intermediate .CH2CH2. on Pt sites. Furthermore, kinetic analyses suggest different reaction mechanisms for hydrodechlorination of 1,2-dichloroethane over Pt and Cu-enriched surfaces in the Pt-Cu bimetallic catalysts.

  4. Photodisintegration of $^4$He into p+t

    SciTech Connect (OSTI)

    R. Nasseripour, B.L. Berman, N. Benmouna, Y. Ilieva, J.-M. Laget

    2009-10-01

    The two-body photodisintegration of $^4$He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at Jefferson Laboratory. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid $^4$He target. This is the first measurement of the photodisintegration of $^4$He above 0.4 GeV. The differential cross sections for the $\\gamma$$^4$He$\\to pt$ reaction have been measured as a function of photon-beam energy and proton-scattering angle, and are compared with the latest model calculations by J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the calculations that include three-body mechanisms, thus confirming their importance. These results reinforce the conclusion of our previous study of the three-body breakup of $^3$He that demonstrated the great importance of three-body mechanisms in the energy region 0.5-0.8 GeV .

  5. Effects of ionomer morphology on oxygen reduction on Pt

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chlistunoff, Jerzy; Pivovar, Bryan

    2015-05-21

    In this paper, the oxygen reduction reaction (ORR) at the interface between platinum and Nafion 1100 equivalent weight was studied as a function of temperature (20–80 °C), humidity (10–100%), scan rate, the manner in which Nafion film was deposited, and the state of the Pt surface using ultramicroelectrodes employing cyclic voltammetry and chronoamperometry. ORR on smooth electrodes was strongly inhibited under specific conditions dependent on temperature, humidity, and scan rate. From the data presented, we postulate that dynamic changes in the molecular structure of the ionomer at the platinum interface result in differences in ORR voltammetry for films prepared andmore » equilibrated under different conditions. The lack of similar changes for rough, platinized electrodes has been attributed to differences in initial ionomer structure and a higher energy barrier for ionomer restructuring. Finally, these model system studies yield insight into the ionomer-catalyst interface of particular interest for polymer electrolyte fuel cells.« less

  6. Dirac node arcs in PtSn4

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wu, Yun; Wang, Lin -Lin; Mun, Eundeok; Johnson, D. D.; Mou, Daixiang; Huang, Lunan; Lee, Yongbin; Bud’ko, S. L.; Canfield, P. C.; Kaminski, Adam

    2016-04-04

    In topological quantum materials1,2,3 the conduction and valence bands are connected at points or along lines in the momentum space. A number of studies have demonstrated that several materials are indeed Dirac/Weyl semimetals4,5,6,7,8. However, there is still no experimental confirmation of materials with line nodes, in which the Dirac nodes form closed loops in the momentum space2,3. Here we report the discovery of a novel topological structure—Dirac node arcs—in the ultrahigh magnetoresistive material PtSn4 using laser-based angle-resolved photoemission spectroscopy data and density functional theory calculations. Unlike the closed loops of line nodes, the Dirac node arc structure arises owing tomore » the surface states and resembles the Dirac dispersion in graphene that is extended along a short line in the momentum space. Here, we propose that this reported Dirac node arc structure is a novel topological state that provides an exciting platform for studying the exotic properties of Dirac fermions.« less

  7. 10 CFR Ch. III (1-1-11 Edition) Pt. 851, App. B

    Broader source: Energy.gov (indexed) [DOE]

    2 10 CFR Ch. III (1-1-11 Edition) Pt. 851, App. B must meet the applicable electrical safety codes and standards referenced in 851.23. 11. NANOTECHNOLOGY SAFETY-RESERVED The ...

  8. AtomiStructure and Composition of Pt3Co Nanocatalysts in Fuel...

    Office of Scientific and Technical Information (OSTI)

    AtomiStructure and Composition of Pt3Co Nanocatalysts in Fuel Cells: An Aberration-Corrected STEM HAADF Study Citation Details In-Document Search Title: AtomiStructure and ...

  9. 42pt5ContractManagementPlanning.pdf | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    2pt5ContractManagementPlanning.pdf More Documents & Publications Acquisition Letter 2009-03 Acquisition Planning-Extending A Management and Operating Contract Without Full and Open...

  10. EFFECT OF PRETREATMENT ON PT-CO/C CATHODE CATALYSTS FOR THE OXYGEN-REDUCTION REACTION

    SciTech Connect (OSTI)

    Fox, E.

    2009-05-13

    In order to reduce the precious metal loading without sacrificing activity and stability, a new method for the preparation of bimetallic catalysts is proposed. Currently, Pt-alloy particles, with 2 to 3 nm in diameter, are loaded on high surface area carbon supports. Of the Pt loaded, only the surface atoms interact with the reactants. In order to increase the Pt utilization per metal particle the new process for catalyst preparation will incorporate a non-noble transition metal core coated with a skin layer of Pt deposited on high surface area carbon. The effect of reducing agent strength during synthesis was also explored. It was determined that the Co addition has a higher impact on catalyst when used with NaBH4 as reducing agent as compared to NaCOOH.

  11. First principles investigation of the initial stage of H-induced missing-row reconstruction of Pd(110) surface

    SciTech Connect (OSTI)

    Padama, Allan Abraham B. [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Kasai, Hideaki, E-mail: kasai@dyn.ap.eng.osaka-u.ac.jp [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Center for Atomic and Molecular Technologies, Osaka University, Suita, Osaka 565-0871 (Japan)

    2014-06-28

    The pathway of H diffusion that will induce the migration of Pd atom is investigated by employing first principles calculations based on density functional theory to explain the origin of missing-row reconstruction of Pd(110).The calculated activation barrier and the H-induced reconstruction energy reveal that the long bridge-to-tetrahedral configuration is the energetically favored process for the initial stage of reconstruction phenomenon. While the H diffusion triggers the migration of Pd atom, it is the latter process that significantly contributes to the activated missing-row reconstruction of Pd(110). Nonetheless, the strong interaction between the diffusing H and the Pd atoms dictates the occurrence of reconstructed surface.

  12. The spin Hall angle and spin diffusion length of Pd measured by spin pumping and microwave photoresistance

    SciTech Connect (OSTI)

    Tao, X. D.; Feng, Z.; Miao, B. F.; Sun, L.; You, B.; Wu, D.; Du, J.; Zhang, W.; Ding, H. F., E-mail: hfding@nju.edu.cn [Department of Physics, National Laboratory of Solid State Microstructures, Nanjing University, 22 Hankou Road, Nanjing 210093 (China)

    2014-05-07

    We present the experimental study of the spin Hall angle (SHA) and spin diffusion length of Pd with the spin pumping and microwave photoresistance effects. The Py/Pd bilayer stripes are excited with an out-of-plane microwave magnetic field. The pure spin current is thus pumped and transforms into charge current via the inverse spin Hall effect (ISHE) in Pd layer, yielding an ISHE voltage. The ISHE voltage can be distinguished from the unwanted signal caused by the anisotropic magnetoresistance according to their different symmetries. Together with Pd thickness dependent measurements of in and out-of-plane precessing angles and effective spin mixing conductance, the SHA and spin-diffusion length of Pd are quantified as 0.0056??0.0007 and 7.3??0.7?nm, respectively.

  13. Impact of Materials Processing on Microstructural Evolution and Hydrogen Isotope Storage Properties of Pd-Rh Alloy Powders.

    SciTech Connect (OSTI)

    Yee, Joshua K

    2015-02-01

    Cryomilled Pd - 10Rh was investiga ted as potential solid - state storage material of hydrogen. Pd - 10Rh was first atomized, and then subsequently cryomilled. The cryomilled Pd - 10Rh was then examined using microstructural characterization techniques including op tical microscopy, electron microscopy, and X - ray diffraction. Pd - 10Rh particles were significantly flattened, increasing the apparent surface area. Microstructural refinement was observed in the cryomilled Pd - 10Rh, generating grains at the nanom etric scale through dislocation - based activity. Hydrogen sorption properties were also characterized, generating both capacity as well as kinetics measurements. It was found that the microstructural refinement due to cryomilling did not play a significant role on hyd rogen sorption properties until the smallest grain size (on the order of %7E25 nm) was achieved. Additionally, the increased surface area and other changes in particle morphology were associated with cryomilling changed the kinetics of hydrogen absorption.

  14. Ab initio molecular dynamics investigations of low-energy recoil events in Ni and NiCo

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Bin; Yuan, Fenglin; Jin, Ke; Zhang, Yanwen; Weber, William J.

    2015-10-06

    Low-energy recoil events in pure Ni and the equiatomic NiCo alloy are studied using ab initio molecular dynamics simulations. We found that the threshold displacement energies are strongly dependent on orientation and weakly dependent on composition. The minimum threshold displacement energies are along the [1 1 0] direction in both pure Ni and the NiCo alloy. Compared to pure Ni, the threshold displacement energies increase slightly in the NiCo alloy due to stronger bonds in the alloy, irrespective of the element type of the PKA. A single Ni interstitial occupying the center of a tetrahedron formed by four Ni atomsmore » and a <1 0 0> split interstitial is produced in pure Ni by the recoils, while only the <1 0 0> split interstitial is formed in the NiCo alloy. Compared to the replacement sequences in pure Ni, anti-site defect sequences are observed in the alloy, which have high efficiency for both producing defects and transporting energy outside of the cascade core. These results provide insights into energy transfer processes occurring in equiatomic alloys under irradiation.« less

  15. Shape coexistence in the neutron-deficient Pt isotopes in a configuration mixing IBM

    SciTech Connect (OSTI)

    Morales, Irving O.; Vargas, Carlos E.; Frank, Alejandro

    2004-09-13

    The recently proposed matrix-coherent state approach for configuration mixing IBM is used to describe the evolving geometry of the neutron deficient Pt isotopes. It is found that the Potential Energy Surface (PES) of the Platinum isotopes evolves, when the number of neutrons decreases, from spherical to oblate and then to prolate shapes, in agreement with experimental measurements. Oblate-Prolate shape coexistence is observed in 194,192Pt isotopes.

  16. Electronic structure of U2PtC2 and U2RhC2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ronning, F.; Zhu, J. -X.

    2015-03-18

    In this study, we present density functional theory calculations within the generalized gradient approximation of U2RhC2 and U2PtC2. We find the calculated density of states are significantly less than that measured by specific heat indicating the need for electronic correlations. The mass enhancement found for U2PtC2 is m*/mband ≈ 4.

  17. Observation of spin rectification in Pt/yttrium iron garnet bilayer

    SciTech Connect (OSTI)

    Rao, Jinwei; Fan, Xiaolong Zhou, Hengan; Zhao, Xiaobing; Zhao, Jing; Zhang, Fengzhen; Xue, Desheng; Ma, Li; Zhou, Shiming

    2015-05-07

    We used the ferromagnetic resonance (FMR) to study the dc voltage generation in Pt 20 nm layer deposited on yttrium iron garnet. Although the main contribution to the FMR voltage comes from the inverse spin Hall effect associated with spin pumping, the spin rectification would also contribute the resonance signal via the “new” magnetoresistance effect in Pt layer. Based on a symmetry consideration, we can separate those two effects through angular dependent resonance amplitude.

  18. Dispersive x-ray synchrotron studies of Pt-C multilayers

    SciTech Connect (OSTI)

    Smither, R.K.; Rodricks, B.; Lamelas, F.; Medjahed, D.; Dos Passos, W.; Clarke, R.; Ziegler, E.; Fontaine, A.

    1989-02-01

    We demonstrate the simultaneous acquisition of high-resolution x-ray absorption spectra and scattering data, using a combination of energy-dispersive optics and a two-dimensional CCD detector. Results are presented on the optical constants of Pt and on the reflectivity of a platinum-carbon multilayer at the L/sub III/ absorption edge of Pt. 12 refs., 5 figs.

  19. Mitigation of the Impact of Pt Contamination on Cu-Zeolite SCR Catalyst

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Performance | Department of Energy Mitigation of the Impact of Pt Contamination on Cu-Zeolite SCR Catalyst Performance Mitigation of the Impact of Pt Contamination on Cu-Zeolite SCR Catalyst Performance Investigates operating conditions under which PGM elements get volatilized and transferred onto the downstream SCR catalyst, resulting in loss of NOx reduction performance deer12_chen.pdf (856.01 KB) More Documents & Publications The Effects of Hydrothermal Agingon a Commercial Cu SCR

  20. Can every Pt atom be utilized in FC electrodes? | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Can every Pt atom be utilized in FC electrodes? Can every Pt atom be utilized in FC electrodes? Presentation about platinum utilization in fuel cell electrodes, presented by Radoslav Adzic, Brookhaven National Laboratory, at the kick-off meeting of the U.S. Department of Energy Fuel Cell Technologies Program's Catalysis Working Group, held May 14, 2012, in Arlington, Virginia. 7_cwg_may2012_adzic.pdf (783.37 KB) More Documents & Publications Platinum Monolayer Electrocatalysts for Oxygen

  1. TUNING OF SIZE AND SHAPE OF AU-PT NANOCATALYST FOR DIRECT METHANOL FUEL CELLS

    SciTech Connect (OSTI)

    Murph, S.

    2011-04-20

    In this paper, we report the precise control of the size, shape and surface morphology of Au-Pt nanocatalysts (cubes, blocks, octahedrons and dogbones) synthesized via a seed-mediated approach. Gold 'seeds' of different aspect ratios (1 to 4.2), grown by a silver-assisted approach, were used as templates for high-yield production of novel Au-Pt nanocatalysts at a low temperature (40 C). Characterization by electron microscopy (SEM, TEM, HRTEM), energy dispersive X-ray analysis (EDX), UV-Vis spectroscopy, zeta-potential (surface charge), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to better understand their physico-chemical properties, preferred reactivities and underlying nanoparticle growth mechanism. A rotating disk electrode was used to evaluate the Au-Pt nanocatalysts electrochemical performance in the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) of direct methanol fuel cells. The results indicate the Au-Pt dogbones are partially and in some cases completely unaffected by methanol poisoning during the evaluation of the ORR. The ORR performance of the octahedron particles in the absence of MeOH is superior to that of the Au-Pt dogbones and Pt-black, however its performance is affected by the presence of MeOH.

  2. Unusual adsorption properties of silver adlayers on the Pt(111) electrode surface

    SciTech Connect (OSTI)

    Marinkovic, N.S.; Wang, J.X.; Adzic, R.R.; Marinkovic, J.S.

    1999-01-07

    Adsorption properties of silver monolayer and bilayer deposited at underpotentials on a Pt(111) electrode were studied by means of linear sweep voltammetry, in situ surface X-ray scattering and infrared spectroelectrochemistry. Surface X-ray scattering measurements show a pseudomorphic Ag monolayer and an incommensurate expanded bilayer on Pt(111) formed at underpotentials. Unusual adsorption properties of the silver layers with respect to the bulk silver are observed. The two Ag adlayers were found to have intermediate adsorption/oxidation characteristics between those of metallic Ag and Pt surfaces with (111) orientation. The Ag monolayer has properties that facilitate adsorption of bisulfate anions and adsorption and oxidation of CO. These properties are closer to the adsorption properties of the Pt(111) surface than to those of Ag(111), which adsorbs sulfate anions and does not adsorb CO. The Ag bilayer on the Pt(111) surface adsorbs sulfate anions as Ag(111) does, but in contrast to the behavior of Ag(111), it adsorbs CO. These properties of the Ag adlayers appear to be a consequence of the charge-transfer process and the electron distribution in the Ag/Pt(111) surface.

  3. Ni{sub 3}Al technology transfer

    SciTech Connect (OSTI)

    Sikka, V.K.; Viswanathan, S.; Santella, M.L.

    1997-04-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, wire, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for: (1) high-strength castable composition for many applications that have been identified; (2) castability (mold type, fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) workability of cast or powder metallurgy product to sheet, bar, and wire. The four issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes the work completed to address some of these issues during FY 1996.

  4. Kinetics of hydrogen isotope exchange in β-phase Pd-H-D

    SciTech Connect (OSTI)

    Luo, Weifang; Cowgill, Donald F.

    2015-07-22

    Hydrogen isotope gas exchange within palladium powders is examined using a batch-type reactor coupled to a residual gas analyzer (RGA). Furthermore, the exchange rates in both directions (H2 + PdD and D2 + PdH) are measured in the temperature range 178–323 K for the samples with different particle sizes. The results show this batch-type exchange is closely approximated as a first-order kinetic process with a rate directly proportional to the surface area of the powder particles. An exchange rate constant of 1.40 ± 0.24 μmol H2/atm cm2 s is found for H2 + PdD at 298 K, 1.4 times higher than that for D2 + PdH, with an activation energy of 25.0 ± 3.2 kJ/mol H for both exchange directions. Finally, a comparison of exchange measurement techniques shows these coefficients, and the fundamental exchange probabilities are in good agreement with those obtained by NMR and flow techniques.

  5. Kinetics of hydrogen isotope exchange in β-phase Pd-H-D

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Luo, Weifang; Cowgill, Donald F.

    2015-07-22

    Hydrogen isotope gas exchange within palladium powders is examined using a batch-type reactor coupled to a residual gas analyzer (RGA). Furthermore, the exchange rates in both directions (H2 + PdD and D2 + PdH) are measured in the temperature range 178–323 K for the samples with different particle sizes. The results show this batch-type exchange is closely approximated as a first-order kinetic process with a rate directly proportional to the surface area of the powder particles. An exchange rate constant of 1.40 ± 0.24 μmol H2/atm cm2 s is found for H2 + PdD at 298 K, 1.4 times highermore » than that for D2 + PdH, with an activation energy of 25.0 ± 3.2 kJ/mol H for both exchange directions. Finally, a comparison of exchange measurement techniques shows these coefficients, and the fundamental exchange probabilities are in good agreement with those obtained by NMR and flow techniques.« less

  6. Tables for Trials and Failures with PD for Designated Confidence Level

    SciTech Connect (OSTI)

    Leach, Janice

    2014-02-01

    Two attachments are provided for performance testing of sensors and other Physical Protection System (PPS) components.#2; The first attachment is a table of Trials and Failures, giving Probability of Detection (PD) for a designated confidence level and sorted by trials.#2; The second attachment contains the same data, sorted by failures.

  7. Kinetics of Hydrogen Isotope Exchange in ?-phase Pd-H-D

    SciTech Connect (OSTI)

    Luo, Weifang; Cowgill, Donald F.

    2015-07-22

    Hydrogen isotope gas exchange within palladium powders is examined using a batch-type reactor coupled to a residual gas analyzer (RGA). Furthermore, the exchange rates in both directions (H2 + PdD and D2 + PdH) are measured in the temperature range 178323 K for the samples with different particle sizes. The results show this batch-type exchange is closely approximated as a first-order kinetic process with a rate directly proportional to the surface area of the powder particles. An exchange rate constant of 1.40 0.24 ?mol H2/atm cm2 s is found for H2 + PdD at 298 K, 1.4 times higher than that for D2 + PdH, with an activation energy of 25.0 3.2 kJ/mol H for both exchange directions. Finally, a comparison of exchange measurement techniques shows these coefficients, and the fundamental exchange probabilities are in good agreement with those obtained by NMR and flow techniques.

  8. SF 6432-NI (02-22-10)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    3-08-10) SECTION II STANDARD TERMS AND CONDITIONS FOR FIXED PRICE CONTRACTS WITH THE NEWLY INDEPENDENT STATES OF THE FORMER SOVIET UNION INDEX OF CLAUSES THE FOLLOWING CLAUSES APPLY TO REQUESTS FOR QUOTATION AND CONTRACTS AS INDICATED UNLESS SPECIFICALLY DELETED, OR EXCEPT TO THE EXTENT THEY ARE SPECIFICALLY SUPPLEMENTED OR AMENDED IN WRITING IN SECTION I. NI01 - ACCEPTANCE OF TERMS AND CONDITIONS Contractor, by signing this Agreement, beginning performance, and/or delivering Items or services

  9. SF 6432-NI (04-95)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    6-08) SECTION II STANDARD TERMS AND CONDITIONS FOR FIXED PRICE CONTRACTS WITH NEW INDEPENDET STATES OF THE FORMER SOVIET UNION INDEX OF CLAUSES THE FOLLOWING CLAUSES APPLY TO REQUESTS FOR QUOTATION AND CONTRACTS AS INDICATED UNLESS SPECIFICALLY DELETED, OR EXCEPT TO THE EXTENT THEY AERE SPECIFICALLY SUPPLEMENTED OR AMENDED IN WRITING IN THE SIGNATURE PAGE OR SECTION I. NI01 - ACCEPTANCE OF TERMS AND CONDITIONS Contractor, by signing this Agreement, beginning performance, and/or delivering Items

  10. Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta) trilayers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Junxue; Xu, Yadong; Aldosary, Mohammed; Tang, Chi; Lin, Zhisheng; Zhang, Shufeng; Lake, Roger; Shi, Jing

    2016-03-02

    Pure spin current, a flow of spin angular momentum without flow of any accompanying net charge, is generated in two common ways. One makes use of the spin Hall effect in normal metals (NM) with strong spin–orbit coupling, such as Pt or Ta. The other utilizes the collective motion of magnetic moments or spin waves with the quasi-particle excitations called magnons. A popular material for the latter is yttrium iron garnet, a magnetic insulator (MI). Here we demonstrate in NM/MI/NM trilayers that these two types of spin currents are interconvertible across the interfaces, predicated as the magnon-mediated current drag phenomenon.more » The transmitted signal scales linearly with the driving current without a threshold and follows the power-law Tn with n ranging from 1.5 to 2.5. Lastly, our results indicate that the NM/MI/NM trilayer structure can serve as a scalable pure spin current valve device which is an essential ingredient in spintronics.« less

  11. Site selective substitution Pt for Ti in KTiOPO{sub 4}:Ga crystals revealed by electron paramagnetic resonance

    SciTech Connect (OSTI)

    Grachev, V.; Meyer, M.; Jorgensen, J.; Malovichko, G.; Hunt, A. W.

    2014-07-28

    Electron Paramagnetic Resonance at low temperatures has been used to characterize potassium titanyl phosphate (KTiOPO{sub 4}) single crystals grown by different techniques. Irradiation with 20?MeV electrons performed at room temperature and liquid nitrogen temperature caused an appearance of electrons and holes. Platinum impurities act as electron traps in KTiOPO{sub 4} creating Pt{sup 3+} centers. Two different Pt{sup 3+} centers were observed, Pt(A) and Pt(D). The Pt(A) centers are dominant in undoped samples, whereas Pt(D)in Ga-doped KTP crystals. Superhyperfine structure registered for Pt(D) centers was attributed to interactions of platinum electrons with {sup 39}K and two {sup 31}P nuclei in their surroundings. In both Pt(A) and Pt(D) centers, Pt{sup 3+} ions substitute for Ti{sup 4+} ions, but with a preference to one of two electrically distinct crystallographic positions. The site selective substitution can be controlled by the Ga-doping.

  12. Effect of Pt and H{sub 2} on n-butane isomerization over Fe and Mn promoted sulfated zirconia

    SciTech Connect (OSTI)

    Song, Xuemin; Reddy, K.R.; Sayari, A.

    1996-06-01

    The activity of a 0.4 wt% Pt-containing Fe and Mn promoted sulfated zirconia (PtSFMZ) catalyst in n-butane isomerization at 35{degrees}C was compared to that of a Pt-free catalyst (SFMZ). The maximum rate of n-butane conversion observed in helium over PtSFMZ was found to be 2.5 times higher than that over the SFMZ catalyst under the same conditions. It is believed that n-butane isomerization proceeds via a bimolecular mechanism in which the formation of hydrogen-deficient intermediates (carbenium ions and butenes), is necessary and the presence of transition metals such as Pt, Fe, and Mn on sulfated zirconia facilitates the formation/accumulation of these intermediates and increases their stability on the catalyst surface. The presence of H{sub 2} had a strong negative effect on n-butane conversion over PtSFMZ, but had no effect over SFMZ. The negative effect of H{sub 2} on PtSFMZ catalyst in n-butane isomerization reaction was attributed to the decreased concentration of butenes in the presence of hydrogen atoms which are formed by the dissociation of H{sub 2} on Pt. The ability of calcined Pt-containing catalysts to activate hydrogen at 35{degrees}C was demonstrated. Reduced SFMZ with or without Pt was not active at 35{degrees}C regardless of the nature of the carrier gas. 42 refs., 5 figs.

  13. The anti-perovskite type hydride InPd{sub 3}H{sub 0.89}

    SciTech Connect (OSTI)

    Kohlmann, H.; Skripov, A.V.; Soloninin, A.V.; Udovic, T.J.

    2010-10-15

    Hydrogenation of tetragonal InPd{sub 3} in the ZrAl{sub 3} type structure (four-fold ccp superstructure) yields a hydride with a cubic AuCu{sub 3} type structure (one-fold ccp superstructure). Deuterium can be located by neutron powder diffraction in octahedral voids surrounded exclusively by palladium, [Pd{sub 6}], which are 88.5(6)% occupied in a statistical manner. The resulting deuteride InPd{sub 3}D{sub 0.89} thus crystallizes in a cubic anti-perovskite type structure (space group Pm3-bar m (no. 221), a=402.25(1) pm at 299(2) K). The Pd-D distance of 201.13(1) pm is typical for interstitial hydrides with palladium. Inelastic neutron scattering on the hydride InPd{sub 3}H{sub 0.89}, which shows a spectrum similar to that of binary palladium hydride, confirms the cubic site symmetry of hydrogen in [Pd{sub 6}] interstices. This is also confirmed by the absence of any quadrupole splitting in the {sup 2}D-NMR signal of the deuteride. {sup 1}H NMR spectra of InPd{sub 3}H{sub 0.89} do not show any motional narrowing. Values found for the H jump rate {tau}{sup -1} in InPd{sub 3}H{sub 0.89} remain below 10{sup 6} s{sup -1} in the studied temperature range 28-360 K, indicating a small hydrogen mobility in InPd{sub 3}H{sub 0.8} as compared with binary palladium hydride, PdH{sub {<=}1}. This can be attributed to the large spatial separation of the [Pd{sub 6}] sites. - Graphical abstract: Hydrogen induces a rearrangement in InPd{sub 3} from a ZrAl{sub 3} type structure to a cubic AuCu{sub 3} type structure, thus forming an anti-perovskite type hydride InPd{sub 3}H{sub 0.89}.

  14. Novel insight into the hydrogen absorption mechanism at the Pd(110) surface

    SciTech Connect (OSTI)

    Ohno, Satoshi E-mail: wilde@iis.u-tokyo.ac.jp; Wilde, Markus E-mail: wilde@iis.u-tokyo.ac.jp; Fukutani, Katsuyuki

    2014-04-07

    The microscopic mechanism of low-temperature (80 K < T < 160 K) hydrogen (H) ingress into the H{sub 2} (<2.66 10{sup ?3} Pa) exposed Pd(110) surface is explored by H depth profiling with {sup 15}N nuclear reaction analysis (NRA) and thermal desorption spectroscopy (TDS) with isotope (H, D) labeled surface hydrogen. NRA and TDS reveal two types of absorbed hydrogen states of distinctly different depth distributions. Between 80 K and ?145 K a near-surface hydride phase evolving as the TDS ?{sub 1} feature at 160 K forms, which initially extends only several nanometers into depth. On the other hand, a bulk-absorbed hydrogen state develops between 80 K and ?160 K which gives rise to a characteristic ?{sub 3} TDS feature above 190 K. These two absorbed states are populated at spatially separated surface entrance channels. The near-surface hydride is populated through rapid penetration at minority sites (presumably defects) while the bulk-absorbed state forms at regular terraces with much lower probability per site. In both cases, absorption of gas phase hydrogen transfers pre-adsorbed hydrogen atoms below the surface and replaces them at the chemisorption sites by post-dosed hydrogen in a process that requires much less activation energy (<100 meV) than monatomic diffusion of chemisorbed H atoms into subsurface sites. This small energy barrier suggests that the rate-determining step of the absorption process is either H{sub 2} dissociation on the H-saturated Pd surface or a concerted penetration mechanism, where excess H atoms weakly bound to energetically less favorable adsorption sites stabilize themselves in the chemisorption wells while pre-chemisorbed H atoms simultaneously transit into the subsurface. The peculiarity of absorption at regular Pd(110) terraces in comparison to Pd(111) and Pd(100) is discussed.

  15. Effect of embedded metal nanocrystals on the resistive switching characteristics in NiN-based resistive random access memory cells

    SciTech Connect (OSTI)

    Yun, Min Ju; Kim, Hee-Dong; Man Hong, Seok; Hyun Park, Ju; Su Jeon, Dong; Geun Kim, Tae

    2014-03-07

    The metal nanocrystals (NCs) embedded-NiN-based resistive random access memory cells are demonstrated using several metal NCs (i.e., Pt, Ni, and Ti) with different physical parameters in order to investigate the metal NC's dependence on resistive switching (RS) characteristics. First, depending on the electronegativity of metal, the size of metal NCs is determined and this affects the operating current of memory cells. If metal NCs with high electronegativity are incorporated, the size of the NCs is reduced; hence, the operating current is reduced owing to the reduced density of the electric field around the metal NCs. Second, the potential wells are formed by the difference of work function between the metal NCs and active layer, and the barrier height of the potential wells affects the level of operating voltage as well as the conduction mechanism of metal NCs embedded memory cells. Therefore, by understanding these correlations between the active layer and embedded metal NCs, we can optimize the RS properties of metal NCs embedded memory cells as well as predict their conduction mechanisms.

  16. Spectral singularity in confined PT symmetric optical potential

    SciTech Connect (OSTI)

    Sinha, Anjana; Roychoudhury, R.

    2013-11-15

    We present an analytical study for the scattering amplitudes (Reflection ?R? and Transmission ?T?), of the periodic PT symmetric optical potential V(x)=W{sub 0}cos{sup 2}x+iV{sub 0}sin2x confined within the region 0 ?x?L, embedded in a homogeneous medium having uniform potential W{sub 0}. The confining length L is considered to be some integral multiple of the period ?. We give some new and interesting results. Scattering is observed to be normal (?T?{sup 2}? 1, ?R?{sup 2}? 1) for V{sub 0}? 0.5, when the above potential can be mapped to a Hermitian potential by a similarity transformation. Beyond this point (V{sub 0} > 0.5) scattering is found to be anomalous (?T?{sup 2}, ?R?{sup 2} not necessarily ?1). Additionally, in this parameter regime of V{sub 0}, one observes infinite number of spectral singularities E{sub SS} at different values of V{sub 0}. Furthermore, for L= 2n?, the transition point V{sub 0}= 0.5 shows unidirectional invisibility with zero reflection when the beam is incident from the absorptive side (Im[V(x)] < 0) but with finite reflection when the beam is incident from the emissive side (Im[V(x)] > 0), transmission being identically unity in both cases. Finally, the scattering coefficients ?R?{sup 2} and ?T?{sup 2} always obey the generalized unitarity relation : ?T|{sup 2}?1|=?(|R{sub R}|{sup 2}|R{sub L}|{sup 2}), where subscripts R and L stand for right and left incidence, respectively.

  17. Soft Landing of Bare PtRu Nanoparticles for Electrochemical Reduction of Oxygen

    SciTech Connect (OSTI)

    Johnson, Grant E.; Colby, Robert J.; Engelhard, Mark H.; Moon, DaeWon; Laskin, Julia

    2015-08-07

    Magnetron sputtering of two independent Pt and Ru targets coupled with inert gas aggregation in a modified commercial source has been combined with soft landing of mass-selected ions to prepare bare 4.5 nm diameter PtRu alloy nanoparticles on glassy carbon electrodes with controlled size and morphology for electrochemical reduction of oxygen in solution. Employing atomic force microscopy (AFM) it is shown that the nanoparticles bind randomly to the glassy carbon electrode at a relatively low coverage of 7 x 104 ions µm-2 and that their average height is centered at 4 nm. Scanning transmission electron microscopy images obtained in the high-angle annular dark field mode (STEM-HAADF) further confirm that the soft-landed PtRu alloy nanoparticles are uniform in size and have a Ru core decorated with small regions of Pt on the surface. Wide-area scans of the electrodes using X-ray photoelectron spectroscopy (XPS) reveal the presence of both Pt and Ru in relative atomic concentrations of ~9% and ~33%, respectively. Deconvolution of the high energy resolution XPS spectra in the Pt4f and Ru3d regions indicates the presence of both oxidized Pt and Ru. The substantially higher loading of Ru compared to Pt and enrichment of Pt at the surface of the alloy nanoparticles is confirmed by wide-area analysis of the electrodes using time-of-flight medium energy ion scattering (TOF-MEIS) employing both 80 keV He+ and O+ ions. The activity of electrodes containing 7 x 104 ions µm-2 of bare 4.5 nm PtRu nanoparticles toward the electrochemical reduction of oxygen was evaluated employing cyclic voltammetry (CV) in 0.1 M HClO4 and 0.5 M H2SO4 solutions. In both electrolytes a pronounced reduction peak was observed during O2 purging of the solution that was not evident during purging with Ar. Repeated electrochemical cycling of the electrodes revealed little evolution in the shape or position of the voltammograms indicating high stability of the alloy nanoparticles supported on glassy

  18. Local structure study of Fe dopants in Ni-deficit Ni3Al alloys

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    V. N. Ivanovski; Umicevic, A.; Belosevic-Cavor, J.; Lei, Hechang; Li, Lijun; Cekic, B.; Koteski, V.; Petrovic, C.

    2015-08-24

    We found that the local electronic and magnetic structure, hyperfine interactions, and phase composition of polycrystalline Ni–deficient Ni 3-x FexAl (x = 0.18 and 0.36) were investigated by means of 57 Fe Mössbauer spectroscopy. The samples were characterized by X–ray diffraction and magnetization measurements. The ab initio calculations performed with the projector augmented wave method and the calculations of the energies of iron point defects were done to elucidate the electronic structure and site preference of Fe doped Ni 3 Al. Moreover, the value of calculated electric field gradient tensor Vzz=1.6 1021Vm-2 matches well with the results of Mössbauer spectroscopymore » and indicates that the Fe atoms occupy Ni sites.« less

  19. NiW and NiRu Bimetallic Catalysts for Ethylene Steam Reforming: Alternative Mechanisms for Sulfur Resistance

    SciTech Connect (OSTI)

    Rangan, M.; Yung, M. M.; Medlin, J. W.

    2012-06-01

    Previous investigations of Ni-based catalysts for the steam reforming of hydrocarbons have indicated that the addition of a second metal can reduce the effects of sulfur poisoning. Two systems that have previously shown promise for such applications, NiW and NiRu, are considered here for the steam reforming of ethylene, a key component of biomass derived tars. Monometallic and bimetallic Al{sub 2}O{sub 3}-supported Ni and W catalysts were employed for ethylene steam reforming in the presence and absence of sulfur. The NiW catalysts were less active than Ni in the absence of sulfur, but were more active in the presence of 50 ppm H{sub 2}S. The mechanism for the W-induced improvements in sulfur resistance appears to be different from that for Ru in NiRu. To probe reasons for the sulfur resistance of NiRu, the adsorption of S and C{sub 2}H{sub 4} on several bimetallic NiRu alloy surfaces ranging from 11 to 33 % Ru was studied using density functional theory (DFT). The DFT studies reveal that sulfur adsorption is generally favored on hollow sites containing Ru. Ethylene preferentially adsorbs atop the Ru atom in all the NiRu (111) alloys investigated. By comparing trends across the various bimetallic models considered, sulfur adsorption was observed to be correlated with the density of occupied states near the Fermi level while C{sub 2}H{sub 4} adsorption was correlated with the number of unoccupied states in the d-band. The diverging mechanisms for S and C{sub 2}H{sub 4} adsorption allow for bimetallic surfaces such as NiRu that enhance ethylene binding without accompanying increases in sulfur binding energy. In contrast, bimetallics such as NiSn and NiW appear to decrease the affinity of the surface for both the reagent and the poison.

  20. Correlation between Pd metal thickness and thermally stable perpendicular magnetic anisotropy features in [Co/Pd]{sub n} multilayers at annealing temperatures up to 500 °C

    SciTech Connect (OSTI)

    An, Gwang Guk; Lee, Ja Bin; Yang, Seung Mo; Yoon, Kap Soo; Kim, Jae Hong; Chung, Woo Seong; Hong, Jin Pyo

    2015-02-15

    We examine highly stable perpendicular magnetic anisotropy (PMA) features of [Co/Pd]{sub 10} multilayers (MLs) versus Pd thickness at various ex-situ annealing temperatures. Thermally stable PMA characteristics were observed up to 500 °C, confirming the suitability of these systems for industrial applications at this temperature. Experimental observations suggest that the choice of equivalent Co and Pd layer thicknesses in a ML configuration ensures thermally stable PMA features, even at higher annealing temperatures. X-ray diffraction patterns and cross-sectional transmission electron microscopy images were obtained to determine thickness, post-annealing PMA behavior, and to explore the structural features that govern these findings.

  1. High-performance, low Pt content catalysts for the electroreduction of oxygen in polymer-electrolyte fuel cells

    SciTech Connect (OSTI)

    Fournier, J.; Faubert, G.; Tilquin, J.Y.; Cote, R.; Guay, D.; Dodelet, J.P.

    1997-01-01

    Pt-included and Pt-supported catalysts have been synthesized using graphite and carbon black supports of various specific areas. The graphites are KS6 (20 m{sup 2}/g), HS100 (110 m{sup 2}/g), and HS300 (305 m{sup 2}/g) from Lonza, and the carbon blacks are Vulcan (254 m{sup 2}/g) and Black Pearls (1475 m{sup 2}/g) from Cabot. The Pt-included and Pt-supported catalysts were used at the cathode of a H{sub 2}/O{sub 2} fuel cell, and their polarization curves were compared to each other and to those of various Pt-supported catalysts from E-TEK. In the high current region of interest to fuel cell developers, it is shown that Pt-supported catalysts perform better than Pt-included ones when the specific area of the support is small. The contrary is true when the specific area of the support is large. The best catalysts are HS300-Pti [8.3 weight percent (w/o) Pt included in HS300 graphite] and Vu-Pti (6.1 w/o Pt included in Vulcan XC-72R). These catalysts display very high mass and specific activities for O{sub 2} reduction. Furthermore, the iR-corrected polarization curves of both HS300-Pti (with a Pt loading of 0.110 mg/cm{sup 2}) and Vu-Pti (with a Pt loading of 0.070 mg/cm{sup 2}) cross at high current the polarization curve of the electrode prepared with E-TEK20 (20 w/o of supported Pt, with a Pt loading of 0.287 mg/cm{sup 2}). Pt inclusion in graphite or carbon black is therefore an interesting way of reducing the Pt loading of fuel cell cathodes without lowering electrochemical performance. HS300-Pti have been characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. These analyses indicate that they both contain metallic Pt and Pt(II and IV) oxides and/or hydroxides.

  2. Cross sections for proton-induced reactions on Pd isotopes at energies relevant for the {gamma} process

    SciTech Connect (OSTI)

    Dillmann, I.; Coquard, L.; Domingo-Pardo, C.; Kaeppeler, F.; Marganiec, J.; Uberseder, E.; Giesen, U.; Heiske, A.; Feinberg, G.; Hentschel, D.; Hilpp, S.; Leiste, H.; Rauscher, T.; Thielemann, F.-K.

    2011-07-15

    Proton-activation reactions on natural and enriched palladium samples were investigated via the activation technique in the energy range of E{sub p}=2.75-9 MeV, close to the upper end of the respective Gamow window of the {gamma} process. We have determined cross sections for {sup 102}Pd(p, {gamma}){sup 103}Ag, {sup 104}Pd(p, {gamma}){sup 105}Ag, and {sup 105}Pd(p, n){sup 105}Ag, as well as partial cross sections of {sup 104}Pd(p, n){sup 104}Ag{sup g}, {sup 105}Pd(p, {gamma}){sup 106}Ag{sup m}, {sup 106}Pd(p, n){sup 106}Ag{sup m}, and {sup 110}Pd(p, n){sup 110}Ag{sup m} with uncertainties between 3% and 15% for constraining theoretical Hauser-Feshbach rates and for direct use in {gamma}-process calculations.

  3. Geometric and Electronic Structures of the Ni(I) and Methyl-Ni(III)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Intermediates of Methyl-Coenzyme M Reductase 9 Geometric and Electronic Structures of the Ni(I) and Methyl-Ni(III) Intermediates of Methyl-Coenzyme M Reductase Methyl-coenzyme M reductase (MCR) from methanogenic archaea catalyzes the terminal step in biological methane synthesis. Using coenzyme B (CoBSH) as the two-electron donor, MCR reduces methyl-coenzyme M (methyl-SCoM) to form methane and the heterodisulfide product, CoBS-SCoM. MCR contains an essential redox active nickel tetrapyrrolic

  4. Transmutation-induced embrittlement of V-Ti-Ni and V-Ni alloys in HFIR

    SciTech Connect (OSTI)

    Ohnuki, S.; Takahashi, H.; Garner, F.A.; Pawel, J.E.

    1996-04-01

    Vanadium, V-1Ni, V-10Ti and V-10Ti-1Ni (at %) were irradiated in HFIR to doses ranging from 18 to 30 dpa and temperatures between 300 and 600C. Since the irradiation was conducted in a highly thermalized neutron spectrum without shielding against thermal neutrons, significant levels of chromium (15-22%) were formed by transmutation. The addition of such large chromium levels strongly elevated the ductile to brittle transition temperature. At higher irradiation temperatures radiation-induced segregation of transmutant Cr and solute Ti at specimen surfaces leads to strong increases in the density of the alloy.

  5. A method for the formation of Pt metal nanoparticle arrays using nanosecond pulsed laser dewetting

    SciTech Connect (OSTI)

    Owusu-Ansah, Ebenezer; Horwood, Corie A.; Birss, Viola I.; Shi, Yujun J.; El-Sayed, Hany A.

    2015-05-18

    Nanosecond pulsed laser dewetting of Pt thin films, deposited on a dimpled Ta (DT) surface, has been studied here in order to form ordered Pt nanoparticle (NP) arrays. The DT substrate was fabricated via a simple electrochemical anodization process in a highly concentrated H{sub 2}SO{sub 4} and HF solution. Pt thin films (3–5 nm) were sputter coated on DT and then dewetted under vacuum to generate NPs using a 355 nm laser radiation (6–9 ns, 10 Hz). The threshold laser fluence to fully dewet a 3.5 nm thick Pt film was determined to be 300 mJ/cm{sup 2}. Our experiments have shown that shorter irradiation times (≤60 s) produce smaller nanoparticles with more uniform sizes, while longer times (>60 s) give large nanoparticles with wider size distributions. The optimum laser irradiation time of 1 s (10 pulses) has led to the formation of highly ordered Pt nanoparticle arrays with an average nanoparticle size of 26 ± 3 nm with no substrate deformation. At the optimum condition of 1 s and 500 mJ/cm{sup 2}, as many as 85% of the dewetted NPs were found neatly in the well-defined dimples. This work has demonstrated that pulsed laser dewetting of Pt thin films on a pre-patterned dimpled substrate is an efficient and powerful technique to produce highly ordered Pt nanoparticle arrays. This method can thus be used to produce arrays of other high-melting-point metal nanoparticles for a range of applications, including electrocatalysis, functionalized nanomaterials, and analytical purposes.

  6. Controlled synthesis of concave tetrahedral palladium nanocrystals by reducing Pd(acac){sub 2} with carbon monoxide

    SciTech Connect (OSTI)

    Zhu, Hai; Chi, Quan; Zhao, Yanxi; Li, Chunya; Tang, Heqing; Li, Jinlin; Huang, Tao; Liu, Hanfan; Institute of Chemistry, Chinese Academy of Science, Beijing 100080

    2012-11-15

    Graphical abstract: By using CO as a reducing agent, uniform and well-defined concave tetrahedral Pd nanocrystals were successfully synthesized. CO flow rate was the most essential for the formation of the concave tetrahedral nanostructures. The morphologies and sizes of the final products can be well controlled by adjusting the flow rate of CO. Highlights: ? By using CO as a reducing agent, concave tetrahedral Pd nanocrystals were obtained. ? CO flow rate is critical to the formation of concave tetrahedral Pd nanocrystals. ? The selective adsorption of CO on (1 1 0) facets is essential to concave Pd tetrahedra. -- Abstract: CO reducing strategy to control the morphologies of palladium nanocrystals was investigated. By using CO as a reducing agent, uniform and well-defined concave tetrahedral Pd nanocrystals with a mean size of about 55 2 nm were readily synthesized with Pd(acac){sub 2} as a precursor and PVP as a stabilizer. The structures of the as-prepared Pd nanocrystals were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), ultravioletvisible (UVvis) absorption spectroscopy and electrochemical measurements. The results demonstrated that CO was the most essential for the formation of the concave tetrahedral Pd nanostructures. The morphologies and sizes of the final products can be well controlled by adjusting the flow rate of CO. The most appropriate CO flow rate, temperature and time for the formation of the ideal concave tetrahedral Pd nanocrystals was 0.033 mL s{sup ?1}, 100 C and 3 h, respectively.

  7. Microstructures in rapidly solidified Ni-Mo alloys

    SciTech Connect (OSTI)

    Jayaraman, N.; Tewari, S.N.; Hemker, K.J.; Glasgow, T.K.

    1985-01-01

    Ni-Mo alloys of compositions ranging from pure Ni to Ni-40 at % Mo were rapidly solidified by chill block melt spinning in vacuum and were examined by optical metallography, x-ray diffraction and transmission electron microscopy. Rapid solidification resulted in an extension of molybdenum solubility in nickel from 28 to 37.5 at %. A number of different phases and microstructures were seen at different depths (solidification conditions) from the quenched surface of the melt spun ribbons.

  8. Effects of Reduction Temperature and Metal-Support Interactions on the Catalytic Activity of Pt/g-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2.

    SciTech Connect (OSTI)

    Alexeev,O.; Chin, S.; Engelhard, M.; Ortiz-Soto, L.; Amiridis, M.

    2005-01-01

    TiO2- and -Al2O3-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in situ FTIR spectroscopy after activation at various conditions, and their catalytic properties were examined for the oxidation of CO in the absence and presence of H2 (PROX). When {gamma}-Al{sub 2}O{sub 3} was used as the support, the catalytic, electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatment conditions. In contrast, the surface properties and catalytic activity of Pt/TiO2 were strongly influenced by the pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron density on Pt, altering its chemisorptive properties, weakening the Pt-CO bonds, and increasing its activity for the oxidation of CO. The in situ FTIR data suggest that both the terminal and bridging CO species adsorbed on fully reduced Pt are active for this reaction. The high activity of Pt/TiO2 for the oxidation of CO can also be attributed to the ability of TiO2 to provide or stabilize highly reactive oxygen species at the metal-support interface. However, such species appear to be more reactive toward H{sub 2} than CO. Consequently, Pt/TiO{sub 2} shows substantially lower selectivities toward CO oxidation under PROX conditions than Pt/{gamma}-Al{sub 2}O{sub 3}.

  9. Effects of Reduction Temperature and Metal-support Interactions on the Catalytic Activity of Pt/γ-Al2O3 and Pt/TiO2 for the Oxidation of CO in the Presence and Absence of H2

    SciTech Connect (OSTI)

    Alexeev, Oleg S.; Chin, Soo Yin; Engelhard, Mark H.; Ortiz-Soto, Lorna; Amiridis, Michael D.

    2005-12-15

    TiO2- and ?-Al2O3-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in-situ FTIR after activation at various conditions and their catalytic properties were examined for the oxidation of CO in the absence and presence of H2 (PROX). When ?-Al2O3 was used as the support, the catalytic, electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatment conditions. In contrast, the surface properties and catalytic activity of Pt/TiO2 were strongly influenced by the pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron density on Pt, altering its chemisorptive properties, weakening the Pt-CO bonds, and increasing its activity for the oxidation of CO. The in-situ FTIR data suggest that both the terminal and bridging CO species adsorbed on fully reduced Pt are active for this reaction. The high activity of Pt/TiO2 for the oxidation of CO can also be attributed to the ability of TiO2 to provide or stabilize highly reactive oxygen species at the metal-support interface. However, such species appear to be more reactive towards H2 than CO. Consequently, Pt/TiO2 shows substantially lower selectivities towards CO oxidation under PROX conditions than Pt/?-Al2O3.

  10. Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Petrie, Jonathan R.; Cooper, Valentino R.; Freeland, John W.; Meyer, Tricia L.; Zhang, Zhiyong; Lutterman, Daniel A.; Lee, Ho Nyung

    2016-02-11

    Strain is known to greatly influence low-temperature oxygen electrocatalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and metal-air batteries. Still, its catalytic impact on transition-metal oxide thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO3 to systematically determine its influence on both the oxygen reduction and oxygen evolution reaction. Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals such as Pt. We attribute the improved bifunctionality to strain-induced splitting of themore » eg orbitals, which can customize orbital asymmetry at the surface. Lastly, analogous to strain-induced shifts in the d-band center of noble metals relative to the Fermi level, such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active oxides.« less

  11. Sources of stress gradients in electrodeposited Ni MEMS. (Conference...

    Office of Scientific and Technical Information (OSTI)

    Title: Sources of stress gradients in electrodeposited Ni MEMS. The ability of future integrated metal-semiconductor micro-systems such as RF MEMS to perform highly complex ...

  12. Numerical Simulation of Ni Grain Growth in a Thermal Gradient

    Office of Scientific and Technical Information (OSTI)

    665C Numerical Simulation of Ni Grain Growth in a Thermal Gradient Sandia National Laboratories John A. Mitchell and Veena Tikare Sandia National Laboratories, Albuquerque New ...

  13. Competition between Order and Phase Separation in Au-Ni

    SciTech Connect (OSTI)

    Reichert, H.; Schoeps, A.; Ramsteiner, I.B.; Bugaev, V.N.; Shchyglo, O.; Udyansky, A.; Dosch, H.; Asta, M.; Drautz, R.; Honkimaeki, V.

    2005-12-02

    We have measured and theoretically analyzed the diffuse scattering in the binary alloy system Au-Ni, which has been proposed as a testing ground for theories of alloy phase stability. We found strong evidence that in the alloys Au{sub 3}Ni and Au{sub 3}Ni{sub 2}, fluctuations of both ordering- and clustering-type are competing with each other. Our results resolve a long-standing controversy on the balance of relaxation and mixing energies in this alloy system and explain recent findings of ordering in thin Au-Ni films.

  14. Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; Hong, Kunlun

    2015-02-05

    The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results pavedmore » the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.« less

  15. Pt nanoparticles modified by rare earth oxides: Electronic effect and influence to catalytic hydrogenation of 3-phenoxybenzaldehyde

    SciTech Connect (OSTI)

    Mou, Zhigang; Han, Ming; Li, Gang; Du, Yukou; Yang, Ping; Zhang, Hailu; Deng, Zongwu

    2013-11-15

    Graphical abstract: - Highlights: • The rare earths modified Pt/Al{sub 2}O{sub 3} were prepared by colloidal deposition method. • Modification of Pt by the rare earth enhanced catalytic hydrogenation activity. • The activity improvement is due to electron interaction between Pt and rare earth. • The hydrogenation mechanism of rare earth modified Pt catalyst was proposed. - Abstract: The rare earth elements (La, Ce, Nd, Sm, Pr, and Gd) modified Pt/Al{sub 2}O{sub 3} catalysts were prepared by the colloidal deposition and chemical reduction methods, respectively. Pt nanoparticles with average size 3 ± 0.5 nm were uniformly dispersed on the surface of Al{sub 2}O{sub 3} for the samples prepared by the colloidal deposition method, which exhibited higher activities in the hydrogenation of 3-phenoxybenzadehyde than the corresponding samples prepared by chemical reduction method. Moreover, except Gd, the catalysts modified by rare earth elements showed better catalytic performance than unmodified Pt/Al{sub 2}O{sub 3}. For Pt–Ce/Al{sub 2}O{sub 3} catalyst, when the weight percent of Pt and Ce was 0.5 and 0.25, respectively, the hydrogenation conversion of 3-phenoxybenzaldehyde was 97.3% after 6 h reaction. This activity improvement is due to the electronic interaction between Pt and rare earth elements, which was investigated by X-ray photoelectron spectroscopy.

  16. American Flyers N-I Wine Makers

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Flyers N-I Wine Makers WSI leads charge in local bike events. NSTec recognizes top performers in NNSS mission. Navarro employees enjoy wine making hobby. See page 8. See page 7. Do You Know Where To Find Latest NNSS Info? In late August, a rainstorm in Las Vegas caused flooding near Mt. Charleston that washed the remnants of this summer's Carpenter Fire across U.S. 95, blocking the roadway. It was 11 p.m. on a Sunday night, and the road closure threatened Nevada National Security Site (NNSS)

  17. Enhanced photocatalytic efficiency in zirconia buffered n-NiO/p-NiO single crystalline heterostructures by nanosecond laser treatment

    SciTech Connect (OSTI)

    Molaei, R.; Bayati, M. R.; Alipour, H. M.; Nori, S.; Narayan, J.

    2013-06-21

    We report the formation of NiO based single crystalline p-n junctions with enhanced photocatalytic activity induced by pulsed laser irradiation. The NiO epilayers were grown on Si(001) substrates buffered with cubic yttria-stabilized zirconia (c-YSZ) by using pulsed laser deposition. The NiO/c-YSZ/Si heterostructures were subsequently laser treated by 5 pulses of KrF excimer laser (pulse duration = 25 Multiplication-Sign 10{sup -9} s) at lower energies. Microstructural studies, conducted by X-ray diffraction ({theta}-2{theta} and {phi} techniques) and high resolution transmission electron microscope, showed a cube-on-cube epitaxial relationship at the c-YSZ/Si interface; the epitaxial relationship across the NiO/c-YSZ interface was established as NiO<111 > Double-Vertical-Line Double-Vertical-Line c-YSZ<001> and in-plane NiO<110> Double-Vertical-Line Double-Vertical-Line c-YSZ<100>. Electron microscopy studies showed that the interface between the laser annealed and the pristine region as well as the NiO/c-YSZ interface was atomically sharp and crystallographically continuous. The formation of point defects, namely oxygen vacancies and NiO, due to the coupling of the laser photons with the NiO epilayers was confirmed by XPS. The p-type electrical characteristics of the pristine NiO epilayers turned to an n-type behavior and the electrical conductivity was increased by one order of magnitude after laser treatment. Photocatalytic activity of the pristine (p-NiO/c-YSZ/Si) and the laser-annealed (n-NiO/p-NiO/c-YSZ/Si) heterostructures were assessed by measuring the decomposition rate of 4-chlorophenol under UV light. The photocatalytic reaction rate constants were determined to be 0.0059 and 0.0092 min{sup -1} for the as-deposited and the laser-treated samples, respectively. The enhanced photocatalytic efficiency was attributed to the suppressed charge carrier recombination in the NiO based p-n junctions and higher electrical conductivity. Besides, the oxygen vacancies

  18. Energies of Electronic States of Ni (II) Ion in NiO-Al2O3 Catalyst Prepared by Impregnation

    SciTech Connect (OSTI)

    Obadovic, D. Z.; Kiurski, J.; Marinkovic-Neducin, R. P.

    2007-04-23

    The behavior of NiO-Al2O3 catalysts is strongly dependent on the preparation method, as well as on pretreatment conditions. In the present work we investigated the influences of Ni(II) ion on NiO-Al2O3 catalysts properties due to the preparation by impregnation method. Based on experimental diffuse reflectance spectroscopy (DRS) data of electronic d-d transitions of Ni (II) promoter ion the energies of electronic states in spinel-like structure were calculated, and the most probable scheme of molecular orbital have been proposed.

  19. Tunability of exchange bias in Ni@NiO core-shell nanoparticles obtained by sequential layer deposition

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    D'Addato, Sergio; Spadaro, Maria Chiara; Luches, Paola; Valeri, Sergio; Grillo, Vincenzo; Rotunno, Enzo; Roldan Gutierrez, Manuel A.; Pennycook, Stephen J.; Ferretti, Anna Maria; Capetti, Elena; et al

    2015-01-01

    Films of magnetic Ni@NiO core–shell nanoparticles (NPs, core diameter d ≅ 12 nm, nominal shell thickness variable between 0 and 6.5 nm) obtained with sequential layer deposition were investigated, to gain insight into the relationships between shell thickness/morphology, core-shell interface, and magnetic properties. Different values of NiO shell thickness ts could be obtained while keeping the Ni core size fixed, at variance with conventional oxidation procedures where the oxide shell is grown at the expense of the core. Chemical composition, morphology of the as-produced samples and structural features of the Ni/NiO interface were investigated with x-ray photoelectron spectroscopy and microscopymore » (scanning electron microscopy, transmission electron microscopy) techniques, and related with results from magnetic measurements obtained with a superconducting quantum interference device. The effect of the shell thickness on the magnetic properties could be studied. The exchange bias (EB) field Hbias is small and almost constant for ts up to 1.6 nm; then it rapidly grows, with no sign of saturation. This behavior is clearly related to the morphology of the top NiO layer, and is mostly due to the thickness dependence of the NiO anisotropy constant. The ability to tune the EB effect by varying the thickness of the last NiO layer represents a step towards the rational design and synthesis of core–shell NPs with desired magnetic properties.« less

  20. The adsorption and reaction of vinyl acetate on Au/Pd(100) alloy surfaces

    SciTech Connect (OSTI)

    Li, Zhenjun [Pacific Northwest National Laboratory (PNNL); Calaza, Florencia C [ORNL; Tysoe, Wilfred [University of Wisconsin, Milwaukee

    2012-01-01

    The surface chemistry of vinyl acetate monomer (VAM) is studied on Au/Pd(100) alloys as a function of alloy composition using temperature-programmed desorption and reflection adsorption infrared spectroscopy. VAM adsorbs weakly on isolated palladium sites on the alloy with a heat of adsorption of ~55 kJ/mol, with the plane of the VAM adsorbed close to parallel to the surface. The majority of the VAM adsorbed on isolated sites desorbs molecularly with only a small portion decomposing. At lower gold coverages (below ~0.5 ML of gold), where palladium palladium bridge sites are present, VAM binds to the surface in a distorted geometry via a rehybridized vinyl group. A larger proportion of this VAM decomposes and this reaction is initiated by C\\O bond scission in the VAM to form adsorbed acetate and vinyl species. The implication of this surface chemistry for VAM synthesis on Au/Pd(100) alloys is discussed.

  1. Multiband Te p Based Superconductivity of Ta4Pd3Te16

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Singh, David J.

    2014-10-06

    We recently discovered that Ta4Pd3Te16 is a superconductor that has been suggested to be an unconventional superconductor near magnetism. Here, we report electronic structure calculations showing that despite the layered crystal structure the material is an anisotropic three-dimensional (3D) metal. The Fermi surface contains prominent one-dimensional (1D) and two-dimensional (2D) features, including nested 1D sheets, a 2D cylindrical section, and a 3D sheet. Moreover, the electronic states that make up the Fermi surface are mostly derived from Te p states with small Ta d and Pd d contributions. This places the compound far from magnetic instabilities. The results are discussedmore » in terms of multiband superconductivity.« less

  2. Modulated ferromagnetic ordering and the magnetocaloric response of Eu{sub 4}PdMg

    SciTech Connect (OSTI)

    Ryan, D. H. Legros, Anaëlle; Niehaus, Oliver; Pöttgen, Rainer; Cadogan, J. M.; Flacau, R.

    2015-05-07

    Neutron powder diffraction confirms that the primary ordering mode in Eu{sub 4}PdMg is ferromagnetic with a europium moment of 6.5(2) μ{sub B}. {sup 151}Eu Mössbauer spectroscopy shows that the unusual linear temperature dependence of the magnetisation reported for this system is an intrinsic property and not an artefact of the applied field. The form and temperature evolution of the {sup 151}Eu Mössbauer spectra strongly suggest that there is an incommensurate modulation to the magnetic structure that modifies the basic ferromagnetic order. This modulated structure may be the origin of the broad magnetocaloric response previously observed in Eu{sub 4}PdMg.

  3. FY14 Annual Report for NA-22 Project LA14-FY14-027-PD2Jb "Developing...

    Office of Scientific and Technical Information (OSTI)

    Title: FY14 Annual Report for NA-22 Project LA14-FY14-027-PD2Jb "Developing Accurate Simulations of Correlated Data in Fission Events" Authors: Talou, Patrick 1 ; Vogt, Ramona ...

  4. FY14 Annual Report for NA-22 Project LA14-FY14-027-PD2Jb "Developing...

    Office of Scientific and Technical Information (OSTI)

    FY14 Annual Report for NA-22 Project LA14-FY14-027-PD2Jb "Developing Accurate Simulations ... Visit OSTI to utilize additional information resources in energy science and technology. A ...

  5. Possible Explanation of {sup 4}He Production in a Pd/D{sub 2} System by the TNCF Model

    SciTech Connect (OSTI)

    Kozima, Hideo; Ohta, Masayuki; Fujii, Mitsutaka; Arai, Kunihito; Kudoh, Hitoshi

    2001-07-15

    Experimental data showing generation of {sup 4}He from a Pd sheet-D{sub 2} gas system observed by E. Botta et al. are analyzed by the trapped neutron catalyzed fusion (TNCF) model. The proposed mechanism of {sup 4}He generation is not the direct d-d reaction but the reactions between the trapped neutron and a Pd isotope, n-{sub 46}{sup A}Pd reactions, with a supplemental assumption, decrease of threshold energies for (n,{alpha}) reactions of {sub 46}{sup A}Pd in solids. The arbitrary parameter n{sub n}, the density of the trapped neutron, of the model is determined to be {approx}10{sup 12} cm{sup -3}, which is consistent with values determined in analyses of data in various events in the cold fusion phenomenon.

  6. Biography U. Düsterloh Degree: PD Dr.- Ing. habil. Institution: Clausthal University of Technology.

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    U. Düsterloh Degree: PD Dr.- Ing. habil. Institution: Clausthal University of Technology. Chair: chair for waste disposal technologies and geomechanics. 1982- 1988 field of study: mining engineer 1989- 1993 PhD work - geomechanical investigations on the stability of salt caverns for waste disposal. 2009 Habilitation - proof of stability and integrity of underground excavations in saliniferous formations with special regard to lab tests. 1989 - 2012 chief engineer at Clausthal University of

  7. Electrochemical Synthesis of Pd Nanorods and Nanowires on High Surface Area

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    C Supports - Energy Innovation Portal Startup America Startup America Hydrogen and Fuel Cell Hydrogen and Fuel Cell Find More Like This Return to Search Electrochemical Synthesis of Pd Nanorods and Nanowires on High Surface Area C Supports Brookhaven National Laboratory Contact BNL About This Technology Technology Marketing Summary Anisotropic growth of palladium nanoparticles on high surface area carbon supports is encouraged by the choice of surface preparation and electrochemical

  8. COMMENTS ON ANOMALOUS EFFECTS IN CHARGING OF PD POWDERS WITH HIGH DENSITY HYDROGEN ISOTOPES

    SciTech Connect (OSTI)

    Shanahan, K.

    2009-10-01

    In Kitamura, et al, Pd-containing materials are exposed to isotopes of hydrogen and anomalous results obtained. These are claimed to be a replication of another experiment conducted by Arata and Zhang. Erroneous basic assumptions are pointed out herein that alter the derived conclusions significantly. The final conclusion is that the reported results are likely normal chemistry combined with noise. Thus the claim to have proven that cold fusion is occurring in these systems is both premature and unlikely.

  9. Synthesis of methanol and dimethyl ether from syngas over Pd/ZnO/Al2O3 catalysts

    SciTech Connect (OSTI)

    Lebarbier, Vanessa M.; Dagle, Robert A.; Kovarik, Libor; Lizarazo-Adarme, Jair A.; King, David L.; Palo, Daniel R.

    2012-01-01

    A Pd/ZnO/Al2O3 catalyst was developed for the synthesis of methanol and dimethyl ether (DME) from syngas. Studied were temperatures of operation ranging from 250C to 380C. High temperatures (e.g. 380C) are necessary when combining methanol and DME synthesis with a methanol to gasoline (MTG) process in a single reactor bed. A commercial Cu/ZnO/Al2O3 catalyst, utilized industrially for the synthesis of methanol at 220-280C, suffers from a rapid deactivation when the reaction is conducted at high temperature (>320C). On the contrary, a Pd/ZnO/Al2O3 catalyst was found to be highly stable for methanol and DME synthesis at 380C. The Pd/ZnO/Al2O3 catalyst was thus further investigated for methanol and DME synthesis at P=34-69 bars, T= 250-380C, GHSV= 5 000-18 000 h-1, and molar feeds H2/CO= 1, 2, and 3. Selectivity to DME increased with decreasing operating temperature, and increasing operating pressure. Increased GHSVs and H2/CO syngas feed ratios also enhanced DME selectivity. Undesirable CH4 formation was observed, however, can be minimized through choice of process conditions and by catalyst design. By studying the effect of the Pd loading and the Pd:Zn molar ratio the formulation of the Pd/ZnO/Al2O3 catalyst was optimized. A catalyst with 5% Pd and a Pd:Zn molar ratio of 0.25:1 has been identified as the preferred catalyst. Results indicate that PdZn particles are more active than Pd particles for the synthesis of methanol and less active for CH4 formation. A correlation between DME selectivity and the concentration of acid sites of the catalysts has been established. Hence, two types of sites are required for the direct conversion of syngas to DME: 1) PdZn particles are active for the synthesis of methanol from syngas, and 2) acid sites which are active for the conversion of methanol to DME. Additionally, CO2 formation was problematic as PdZn was found to be active for the water-gas-shift (WGS) reaction, under all the conditions evaluated.

  10. Structure and Reactivity of Surface Oxides on Pt(110) during Catalytic CO Oxidation

    SciTech Connect (OSTI)

    Ackermann, M.D.; Pedersen, T.M.; Hammer, B.; Hendriksen, B.L.M.; Bobaru, S.C.; Frenken, J.W.M.; Robach, O.; Quiros, C.

    2005-12-16

    We present the first structure determination by surface x-ray diffraction during the restructuring of a model catalyst under reaction conditions, i.e., at high pressure and high temperature, and correlate the restructuring with a change in catalytic activity. We have analyzed the Pt(110) surface during CO oxidation at pressures up to 0.5 bar and temperatures up to 625 K. Depending on the O{sub 2}/CO pressure ratio, we find three well-defined structures: namely, (i) the bulk-terminated Pt(110) surface, (ii) a thin, commensurate oxide, and (iii) a thin, incommensurate oxide. The commensurate oxide only appears under reaction conditions, i.e., when both O{sub 2} and CO are present and at sufficiently high temperatures. Density functional theory calculations indicate that the commensurate oxide is stabilized by carbonate ions (CO{sub 3}{sup 2-}). Both oxides have a substantially higher catalytic activity than the bulk-terminated Pt surface.

  11. Break-up of Pt catalyst surfaces by high CO coverage

    SciTech Connect (OSTI)

    Tao, Feng; Dag, Sefa; Wang, Lin-Wang; Liu, Zhi; Butcher, Derek; Bluhm, Henrik; Salmeron, Miquel; Somorjai, Gabor

    2009-09-16

    Stepped Platinum surfaces were found to undergo extensive and reversible restructuring when exposed to CO at pressures above 0.1 Torr. This radically new and previously unknown restructuring phenomenon, has important implications for Pt based catalytic reactions. Novel Scanning Tunneling Microscopy and Photoelectron Spectroscopy techniques operating under gaseous environments near ambient pressure and temperature revealed that as the CO surface coverage approaches 100percent, the originally flat terraces of stepped Pt crystals break up into nanometer size clusters. At room temperature the crystal surface reverts to its initial flat morphology after pumping away the gas phase CO. Density Functional Theory energy calculations provide a rationale for the observations whereby the creation of increased concentrations of low coordination Pt sites at the edges of the formed nanoclusters relieves the strong CO-CO repulsion in the highly compressed adsorbate film.

  12. Swift heavy ion irradiation of Pt nanocrystals: II. Structural changes and H desorption

    SciTech Connect (OSTI)

    Giulian, R.; Araujo, L.L.; Kluth, P.; Sprouster, D.J.; Schnohr, C.S.; Byrne, A.P.; Ridgway, M.C.

    2014-09-24

    The structural properties and H desorption from embedded Pt nanocrystals (NCs) following irradiation with swift heavy ions were investigated as a function of energy and fluence. From x-ray absorption near-edge spectroscopy analysis, Pt-H bonding was identified in NCs annealed in a forming gas (95% N{sub 2} + 5% H{sub 2}) ambient. The H content decreased upon irradiation and the desorption process was NC-size dependent such that larger NCs required a higher fluence to achieve a H-free state. Pt-H bonding and NC dissolution both perturbed the NC structural parameters (coordination number, bond-length and mean-square relative displacement) as determined with extended x-ray absorption fine structure measurements.

  13. Ultra-low loading Pt nanocatalysts prepared by atomic layer deposition on carbon aerogels

    SciTech Connect (OSTI)

    King, J S; Wittstock, A; Biener, J; Kucheyev, S O; Wang, Y M; Baumann, T F; Giri, S; Hamza, A V; Baeumer, M; Bent, S F

    2008-04-21

    Using atomic layer deposition (ALD), we show that Pt nanoparticles can be deposited on the inner surfaces of carbon aerogels (CA). The resultant Pt-loaded materials exhibit high catalytic activity for the oxidation of CO even at loading levels as low as {approx}0.05 mg Pt/cm{sup 2}. We observe a conversion efficiency of nearly 100% in the temperatures range 150-250 C, and the total conversion rate seems to be only limited by the thermal stability of our CA support in ambient oxygen. Our ALD approach described here is universal in nature, and can be applied to the design of new catalytic materials for a variety of applications, including fuel cells, hydrogen storage, pollution control, green chemistry, and liquid fuel production.

  14. Structural stability of 1100[degree]C heated Pd/k during absorption cycling in protium. [Palladium supported on kieselguhr

    SciTech Connect (OSTI)

    Fisher, I.A.

    1993-03-12

    Pd/k is a hydride forming packing material which is used in the Thermal Cycling Absorption Process (TCAP). Palladium is supported on kieselguhr to create a packing material which will provide adequate void space to prevent excessive pressure drops and flow restrictions. The use of unsupported palladium would result in blockage of columns and clogging of filters due to the small particle size of unsupported palladium hydride powder. During pilot scale demonstrations, it was noted that the Pd/k packing material had degraded causing severe flow restrictions within the TCAP column. A solution to the problem involved the heating of Pd/k at 1,110[degree]C to strengthen the packing material, and render it more resistant to breakdown. The 1, 100[degree]C heated Pd/k has been shown to be more resistant to mechanical breakdown than the Pd/k prior to heat treatment. Two primary modes of Pd/k particle degradation have been identified: mechanical breakdown caused by particle fluidization and degradation caused by absorption/desorption cycling. Absorption/desorption cycling causes the palladium particles within the packing to expanded and contract upon formation and decomposition of the hydride, respectively. This expansion and contraction causes large localized stresses within the packing material, which if these stresses can not be accommodated within the packing will cause the material to crack and degrade. The purpose of this report is to document the results of the absorption/desorption cycling of 1,100[degree]C heated Pd/k and compare these results to the results obtained from the absorption/desorption cycling of Pd/k which had not been heated at 1, 100[degree]C.

  15. Effect of dislocation trapping on deuterium diffusion in deformed, single-crystal Pd

    SciTech Connect (OSTI)

    Heuser, B.J.; King, J.S.

    1998-06-01

    Small-angle neutron scattering (SANS) has been used to characterize deuterium trapping at dislocations in deformed, single-crystal Pd during in situ gas evolution experiments. Two methods of deformation were employed--cold rolling and hydride cycling--which create different dislocation arrangements or substructures in Pd. The reduction of the trapped deuterium concentration at dislocations during evolution was directly monitored with SANS. Exponential decay rates of the trapped concentration were observed for both sample types, as is expected in a bulk diffusion process modified by the dislocation trapping interaction. The deuterium concentration reduction proceeded 1.2 to 1.4 times faster in the cold-rolled sample material than in the cycled material. This is attributed to the presence of a smaller number of dislocation trapping sites in the cold-rolled material. The binding energy of deuterium at dislocations was determined by applying a diffusion-based model. A binding energy of 0.20 eV was found to characterize the trapping interaction in both cold-rolled and hydride-cycled Pd.

  16. Hydrogen Sensor Based on Pd/GeO{sub 2} Using a Low Cost Electrochemical Deposition

    SciTech Connect (OSTI)

    Jawad, M. J.; Hashim, M. R.; Ali, N. K.

    2011-05-25

    This work reports on a synthesis of sub micron germanium dioxide (GeO{sub 2}) on porous silicon (PS) by electrochemical deposition. n-type Si (100) wafer was used to fabricate (PS) using conventional method of electrochemical etching in HF based solution. A GeCl{sub 4} was directly hydrolyzed by hydrogen peroxide to produce pure GeO{sub 2}, and then electrochemically deposited on PS. Followed by palladium (Pd) contact on GeO{sub 2} /PS was achieved by using RF sputtering technique. The grown GeO{sub 2} crystals were characterized using SEM and EDX. I-V characteristics of Pd/ GeO{sub 2} were recorded before and after hydrogen gas exposure as well as with different H{sub 2} concentrations and different applied temperatures. The sensitivity of Pd/ GeO{sub 2} also has been investigated it could be seen to increase significantly with increased hydrogen concentration while it decreased with increase temperature.

  17. Hydrogen sorption characteristics of nanostructured Pd10Rh processed by cryomilling

    SciTech Connect (OSTI)

    Yang, Nancy; Yee, Joshua K.; Zhang, Zhihui; Kurmanaeva, Lilia; Cappillino, Patrick; Stavila, Vitalie; Lavernia, Enrique J.; San Marchi, Chris

    2014-10-03

    Palladium and its alloys are model systems for studying solid-state storage of hydrogen. Mechanical milling is commonly used to process complex powder systems for solid-state hydrogen storage; however, milling can also be used to evolve nanostructured powder to modify hydrogen sorption characteristics. In the present study, cryomilling (mechanical attrition milling in a cryogenic liquid) is used to produce nanostructured palladium-rhodium alloy powder. Characterization of the cryomilled Pd-10Rh using electron microscopy, X-ray diffraction, and surface area analysis reveals that (i) particle morphology evolves from spherical to flattened disk-like particles; while the (ii) crystallite size decreases from several microns to less than 100 nm and (iii) dislocation density increases with increased cryomilling time. Hydrogen absorption and desorption isotherms as well as the time scales for absorption were measured for cryomilled Pd-10Rh, and correlated with observed microstructural changes induced by the cryomilling process. In short, as the microstructure of the Pd-10Rh alloy is refined by cryomilling: (i) the maximum hydrogen concentration in the ?-phase increases, (ii) the pressure plateau becomes flatter, and (iii) the equilibrium hydrogen capacity at 760 Torr increases. In addition, the rate of hydrogen absorption was reduced by an order of magnitude compared to non-cryomilled (atomized) powder.

  18. Recoil Distance Method Lifetime Measurements in 107Cd and 103Pd

    SciTech Connect (OSTI)

    Andgren, K.; Ashley, S. F.; Regan, P. H.; McCutchan, E. A.; Zamfir, N. V.; Casten, R. F.; Meyer, D. A.; Plettner, C.; Vinson, J.; Werner, V.; Williams, E.; Amon, L.; Cakirli, R. B.; Erduran, M. N.; Clark, R. M.; Guerdal, G.; Keyes, K. L.; Papenberg, A.; Pietralla, N.; Rainovski, G.

    2006-04-26

    Preliminary lifetime values have been measured for a number of near-yrast states in the odd-A transitional nuclei 107Cd and 103Pd. The reaction used to populate the nuclei of interest was 98Mo(12C,3nx{alpha})107Cd, 103Pd, with the beam delivered by the tandem accelerator of the Wright Nuclear Structure Laboratory at an incident beam energy of 60 MeV. Our experiment was aimed at the investigation of collective excitations built on the unnatural parity, {nu} h11/2 orbital, specifically by measuring the B(E2) values of decays from the excited levels built on this intrinsic structure, using the Doppler Recoil Distance Method. We report lifetimes and associated transition probabilities for decays from the 15/2- and the 19/2- states in 107Cd and the first measurement of the 15/2- state in 103Pd. These results suggest that neither a simple rotational or vibrational interpretation is sufficient to explain the observed structures.

  19. Colloidal synthesis and characterization of carbon-supported Pd-Cu nanoparticle oxygen reduction electrocatalysts.

    SciTech Connect (OSTI)

    Kariuki, N. N.; Wang, X.; Mawdsley, J. R.; Ferrandon, M. S.; Niyogi, S. G.; Vaughey, J. T.; Myers, D. J.; Chemical Sciences and Engineering Division

    2010-07-27

    The ability to control the size and composition of metal or alloys nanoparticles is important in preparing catalysts. This paper reports a colloidal synthesis methodology for the preparation of monodisperse palladium-copper (Pd-Cu) alloy nanoparticles with an average diameter of 3 nm for the as-prepared particles and 5-10 nm upon removal of the capping agents. Our approach involves the use of metal precursors, capping agents, and reducing agents in controlled ratios for nanoparticle formation in a single organic phase, followed by deposition of the capped nanoparticles on high surface area carbon and removal of the capping agents via heat treatment in either oxidizing or reducing atmosphere. The results of characterizations using transmission electron microscopy-energy dispersive X-ray analysis (TEM-EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), temperature programmed oxidation and reduction combined with mass spectrometry (TPO/TPR-MS), powder X-ray diffraction (XRD), and cyclic voltammetry (CV) are discussed. The resulting high-surface-area-carbon-supported Pd-Cu catalysts (PdCu/C) showed high activity for the oxygen reduction reaction (ORR) in acidic electrolyte. Our study revealed composition and heat-treatment dependent ORR activity.

  20. New lifetime measurements in Pd109 and the onset of deformation at N=60

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bucher, B.; Mach, H.; Aprahamian, A.; Simpson, G. S.; Rissanen, J.; Ghiţă, D. G.; Olaizola, B.; Kurcewicz, W.; Äystö, J.; Bentley, I.; et al

    2015-12-14

    We measured several new subnanosecond lifetimes in 109Pd using the fast-timing βγ γ (t ) method. Fission fragments of the A = 109 mass chain were produced by bombarding natural uranium with 30 MeV protons at the Jyväskylä Ion Guide Isotope Separator On-Line (IGISOL) facility. We obtained lifetimes for excited states in 109Pd populated following β decay of 109Rh. The new lifetimes provide some insight into the evolution of nuclear structure in this mass region. In particular, the distinct structure of the two low-lying 7/2+ states occurring systematically across the Pd isotopic chain is supported by the new lifetime measurements.more » Finally, the available nuclear data indicate a sudden increase in deformation at N = 60 which is related to the strong p-n interaction between πg9/2 and νg7/2 valence nucleons expected in this region.« less

  1. SU-E-T-419: Workflow and FMEA in a New Proton Therapy (PT) Facility

    SciTech Connect (OSTI)

    Cheng, C; Wessels, B; Hamilton, H; Difranco, T; Mansur, D

    2014-06-01

    Purpose: Workflow is an important component in the operational planning of a new proton facility. By integrating the concept of failure mode and effect analysis (FMEA) and traditional QA requirements, a workflow for a proton therapy treatment course is set up. This workflow serves as the blue print for the planning of computer hardware/software requirements and network flow. A slight modification of the workflow generates a process map(PM) for FMEA and the planning of QA program in PT. Methods: A flowchart is first developed outlining the sequence of processes involved in a PT treatment course. Each process consists of a number of sub-processes to encompass a broad scope of treatment and QA procedures. For each subprocess, the personnel involved, the equipment needed and the computer hardware/software as well as network requirements are defined by a team of clinical staff, administrators and IT personnel. Results: Eleven intermediate processes with a total of 70 sub-processes involved in a PT treatment course are identified. The number of sub-processes varies, ranging from 2-12. The sub-processes within each process are used for the operational planning. For example, in the CT-Sim process, there are 12 sub-processes: three involve data entry/retrieval from a record-and-verify system, two controlled by the CT computer, two require department/hospital network, and the other five are setup procedures. IT then decides the number of computers needed and the software and network requirement. By removing the traditional QA procedures from the workflow, a PM is generated for FMEA analysis to design a QA program for PT. Conclusion: Significant efforts are involved in the development of the workflow in a PT treatment course. Our hybrid model of combining FMEA and traditional QA program serves a duo purpose of efficient operational planning and designing of a QA program in PT.

  2. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    DOE Patents [OSTI]

    Gschneidner, Jr., Karl A.; Takeya, Hiroyuki

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd.sub.0.54 Er.sub.0.46)AlNi alloys having a relatively constant .DELTA.Tmc over a wide temperature range.

  3. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    DOE Patents [OSTI]

    Gschneidner, K.A. Jr.; Takeya, Hiroyuki

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd{sub 0.54}Er{sub 0.46})AlNi alloys having a relatively constant {Delta}Tmc over a wide temperature range. 16 figs.

  4. Synthesis and electrochemical properties of NiO nanospindles

    SciTech Connect (OSTI)

    Zhou, Hai; Lv, Baoliang; Xu, Yao; Wu, Dong

    2014-02-01

    Graphical abstract: NiO nanospindles with a different electrochemical activity as compared to those previous reports were synthesized via an agglomeration–dissolution–recrystallization growth process without the addition of any surfactant. - Highlights: • NiO nanospindles were synthesized without the addition of any surfactant. • The agglomeration–dissolution–recrystallization growth process was used to explain the precursors’ formation process of the spindle-like NiO. • As-obtained spindle-like NiO showed a different electrochemical activity as compared to those previous reports. - Abstract: NiO nanospindles were successfully synthesized via a hydrothermal and post-treatment method. The as-synthesized nanospindles were about several hundred nanometers in width and about one micrometer in length. X-ray diffraction (XRD) analysis revealed that the spindle-like structure was cubic NiO phase crystalline. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that these NiO nanospindles were of single crystal nature. On the basis of time-dependent experiments, a possible agglomeration–dissolution–recrystallization growth process was proposed to explain the formation process of the spindle-like precursors. The cyclic voltammetry (CV) measurement showed that the as-prepared spindle-like NiO exhibited a pseudo-capacitance behavior.

  5. Atomic-scale imaging and electronic structure determination of catalytic sites on Pd/Cu near surface alloys

    SciTech Connect (OSTI)

    Tierney, H.L.; Baber, A.E.; Sykes, E.C.H.

    2009-04-15

    Water-gas shift chemistry provides a useful method for producing hydrogen from coal; however, fuel cell applications demand that this hydrogen be free of impurities. Due to their unique properties, Pd/Cu alloys represent an import class of materials used for H purification membranes and also serve as the active metals in many heterogeneous catalysts. Little is known about how Pd and Cu interact electronically in these mixed systems and there is debate in the literature over the direction of charge transfer between the two species. This study used the differential conductance (dI/dV) spectroscopy capabilities of a low-temperature scanning tunneling microscope (STM) to investigate the atomic-scale electronic structure of Pd/Cu surface alloys. dI/dV spectroscopy gives a direct measure of the local density of states of surface sites with subnanometer precision. Results from this work demonstrate that individual, isolated Pd atoms in a Cu lattice are almost electronically identical to their host atoms. Over an energy range that spans 1 eV on either side of the Fermi level, the only significant electronic difference between isolated Pd and their host Cu atoms is that Pd atoms have a very slightly depleted electron density in the region of the Cu surface state maximum.

  6. Photocatalytic reduction of aqueous mercury(II) using multi-walled carbon nanotubes/Pd-ZnO nanocomposite

    SciTech Connect (OSTI)

    Mohamed, R.M.; Abdel Salam, Mohamed

    2014-02-01

    Highlights: MWCNT/Pd-ZnO were used for photocatalytic reduction of Hg{sup 2+}. Photocatalytic reduction of Hg{sup 2+} was dependent on wt% of MWCNT, reaction time, and weight of catalyst. Catalyst re-use revealed the present photocatalyst remain effective and active after five, cycles. - Abstract: Pd-ZnO nanocatalyst supported on multi-walled carbon nanotubes was successfully synthesized via a modified solgel method, and the prepared photocatalyst was used for the environmental remediation of aqueous Hg(II) via photocatalytic reduction under visible light. The prepared MWCNTs/Pd/ZnO nanocomposite photocatalyst was characterized using X-ray diffraction, BrunauerEmmettTeller (BET), transmission electron microscopy, and UVvis spectra (UVvis). The results showed that both Pd and ZnO nanoparticles were well dispersed over the MWCNTs, and a uniform nanocomposite was formed. The results also illustrated that Pd doping can eliminate the recombination of electron-hole pairs in the catalyst, and the presence of MWCNTs in ZnO composite can change surface properties to achieve sensitivity to visible light. The results demonstrated that optimum mass ratio of CNT:ZnO:Pd were 0.04:1.0:0.08, which resulted in the exceptional performance of the photocatalyst to reduce about 100% of Hg(II) in a 100 mg L solution within 30 min.

  7. Isotopic fractionation associated with [NiFe]- and [FeFe]-hydrogenases...

    Office of Scientific and Technical Information (OSTI)

    Isotopic fractionation associated with NiFe- and FeFe-hydrogenases Citation Details In-Document Search Title: Isotopic fractionation associated with NiFe- and ...

  8. SF6432-NI (02-01-12) Fixed Price Former Soviet Union

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Retrieve latest version electronically. SF 6432-NI (020112) SECTION II STANDARD TERMS ... 150,000 Control : SF 6432-NI Title: Standard Terms & Conditions for Fixed Price ...

  9. WO3 and HPA Based System for Ultra-High Activity and Stability of Pt

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    catalysts in PEMFC Cathodes | Department of Energy WO3 and HPA Based System for Ultra-High Activity and Stability of Pt catalysts in PEMFC Cathodes WO3 and HPA Based System for Ultra-High Activity and Stability of Pt catalysts in PEMFC Cathodes These slides were presented at the 2010 New Fuel Cell Projects Meeting on September 28, 2010. 8_nrel_turner.pdf (4.39 MB) More Documents & Publications Catalysis Working Group Meeting: January 2015 DOE's Fuel Cell Catalyst R&D Activities

  10. High-frequency signal transmission through single-atom contacts of Au and Pt

    SciTech Connect (OSTI)

    Aoyama, Shodai; Kurokawa, Shu; Sakai, Akira

    2015-03-23

    Signal transmission through atom-sized contacts of Au and Pt has been studied at room temperature for frequencies from 9 kHz to 1 GHz and for conductances (1?10)G{sub 0} (G?2e{sup 2}/h is the quantum unit of conductance). We measured the frequency spectrum of S parameter S{sub 21}=|S{sub 21}|e{sup i?} and found ??0 up to 1?GHz for all contacts irrespective of their conductance. Our observations directly prove that the atom-sized contacts of Au and Pt, including their single-atom contacts, behave as a pure resistance in the RF regime.

  11. Spin-wave excitation and propagation in microstructured waveguides of yttrium iron garnet/Pt bilayers

    SciTech Connect (OSTI)

    Pirro, P.; Chumak, A. V.; Lägel, B.; Leven, B.; Hillebrands, B.; Brächer, T.; Graduate School Materials Science in Mainz, Gottlieb-Daimler-Strasse 47, D-67663 Kaiserslautern ; Dubs, C.; Surzhenko, O.; Görnert, P.

    2014-01-06

    We present an experimental study of spin-wave excitation and propagation in microstructured waveguides consisting of a 100 nm thick yttrium iron garnet/platinum (Pt) bilayer. The life time of the spin waves is found to be more than an order of magnitude higher than in comparably sized metallic structures, despite the fact that the Pt capping enhances the Gilbert damping. Utilizing microfocus Brillouin light scattering spectroscopy, we reveal the spin-wave mode structure for different excitation frequencies. An exponential spin-wave amplitude decay length of 31 μm is observed which is a significant step towards low damping, insulator based micro-magnonics.

  12. Nanostructured electrocatalyst for fuel cells : silica templated synthesis of Pt/C composites.

    SciTech Connect (OSTI)

    Stechel, Ellen Beth; Switzer, Elise E.; Fujimoto, Cy H.; Atanassov, Plamen Borissov; Cornelius, Christopher James; Hibbs, Michael R.

    2007-09-01

    Platinum-based electrocatalysts are currently required for state-of-the-art fuel cells and represent a significant portion of the overall fuel cell cost. If fuel cell technology is to become competitive with other energy conversion technologies, improve the utilization of precious metal catalysts is essential. A primary focus of this work is on creating enhanced nanostructured materials which improve precious-metal utilization. The goal is to engineer superior electrocatalytic materials through the synthesis, development and investigation of novel templated open frame structures synthesized in an aerosol-based approach. Bulk templating methods for both Pt/C and Pt-Ru composites are evaluated in this study and are found to be limited due to the fact that the nanostructure is not maintained throughout the entire sample. Therefore, an accurate examination of structural effects was previously impossible. An aerosol-based templating method of synthesizing nanostructured Pt-Ru electrocatalysts has been developed wherein the effects of structure can be related to electrocatalytic performance. The aerosol-based templating method developed in this work is extremely versatile as it can be conveniently modified to synthesize alternative materials for other systems. The synthesis method was able to be extended to nanostructured Pt-Sn for ethanol oxidation in alkaline media. Nanostructured Pt-Sn electrocatalysts were evaluated in a unique approach tailored to electrocatalytic studies in alkaline media. At low temperatures, nanostructured Pt-Sn electrocatalysts were found to have significantly higher ethanol oxidation activity than a comparable nanostructured Pt catalyst. At higher temperatures, the oxygen-containing species contribution likely provided by Sn is insignificant due to a more oxidized Pt surface. The importance of the surface coverage of oxygen-containing species in the reaction mechanism is established in these studies. The investigations in this work present

  13. Coadsorption of perchlorate and bisulfate ions with Tl adatoms on Pt(111): A SNIFTERS study

    SciTech Connect (OSTI)

    Marinkovic, N.S.; Fawsett, W.R.; Wang, J.X.; Adzic, R.R.

    1995-12-07

    In situ reflection infrared spectroscopy with electrochemical modulation has been used to investigate the coadsorption of anions for the system Tl{sub ads}/Pt(111) in dilute sulfuric and perchloric acids. For the first time evidence of coadsorption of perchlorate induced by underpotentially deposited Tl atoms is reported. The spectroscopic data show that the platinum surface is covered by Tl adatoms and by perchlorate or bisulfate from E = 0.4 V up to the onset of the Tl stripping peak. The possible structures of the Tl-ClO{sub 4} and Tl-HSO{sub 4} adlayers at Pt(111) are discussed. 20 refs., 4 figs.

  14. Tests of Four PT-415 Coolers Installed in the Drop-in Mode

    SciTech Connect (OSTI)

    Green, Michael A.; Wang, S.T.

    2008-07-08

    The superconducting magnets and absorbers for MICE will be cooled using PT415 pulse tube coolers. The cooler 2nd stage will be connected to magnets and the absorbers through a helium or hydrogen re-condensing system. It was proposed that the coolers be connected to the magnets in such a way that the cooler can be easily installed and removed, which permits the magnets to be shipped without the coolers. The drop-in mode requires that the cooler 1st stage be well connected to the magnet shields and leads through a low temperature drop demountable connection. The results of the PT415 drop-in cooler tests are presented.

  15. ARM - Field Campaign - 2005 MASE-MArine Stratus Experiment-Pt. Reyes, CA

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    5 MASE-MArine Stratus Experiment-Pt. Reyes, CA ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : 2005 MASE-MArine Stratus Experiment-Pt. Reyes, CA 2005.07.05 - 2005.07.27 Lead Scientist : Peter Daum For data sets, see below. Abstract The MArine Stratus Experiment (MASE) was designed to examine the influences of anthropogenic aerosols on marine stratus clouds so that the relevant processes can be more

  16. ARM - Field Campaign - MASRAD: Cloud Study from the 2NFOV at Pt. Reyes

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Field Campaign govCampaignsMASRAD: Cloud Study from the 2NFOV at Pt. Reyes Field Campaign Campaign Links AMF Point Reyes Website ARM Data Discovery Browse Data Related Campaigns MArine Stratus Radiation Aerosol and Drizzle (MASRAD) IOP 2005.03.14, Miller, AMF Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : MASRAD: Cloud Study from the 2NFOV at Pt. Reyes Field Campaign 2005.06.02 - 2005.09.30 Lead Scientist : Warren Wiscombe For

  17. ARM - Field Campaign - MASRAD: Pt. Reyes Stratus Cloud and Drizzle Study

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    govCampaignsMASRAD: Pt. Reyes Stratus Cloud and Drizzle Study Campaign Links AMF Point Reyes Website ARM Data Discovery Browse Data Related Campaigns MArine Stratus Radiation Aerosol and Drizzle (MASRAD) IOP 2005.03.14, Miller, AMF Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : MASRAD: Pt. Reyes Stratus Cloud and Drizzle Study 2005.07.07 - 2005.07.31 Lead Scientist : Richard Coulter For data sets, see below. Abstract The primary goal

  18. Effect of Particle Size and Operating Conditions on Pt3Co PEMFC Cathode Catalyst Durability

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gummalla, Mallika; Ball, Sarah; Condit, David; Rasouli, Somaye; Yu, Kang; Ferreira, Paulo; Myers, Deborah; Yang, Zhiwei

    2015-05-29

    The initial performance and decay trends of polymer electrolyte membrane fuel cells (PEMFC) cathodes with Pt3Co catalysts of three mean particle sizes (4.9 nm, 8.1 nm, and 14.8 nm) with identical Pt loadings are compared. Even though the cathode based on 4.9 nm catalyst exhibited the highest initial electrochemical surface area (ECA) and mass activity, the cathode based on 8.1 nm catalyst showed better initial performance at high currents. Owing to the low mass activity of the large particles, the initial performance of the 14.8 nm Pt3Co-based electrode was the lowest. The performance decay rate of the electrodes with themore » smallest Pt3Co particle size was the highest and that of the largest Pt3Co particle size was lowest. Interestingly, with increasing number of decay cycles (0.6 to 1.0 V, 50 mV/s), the relative improvement in performance of the cathode based on 8.1 nm Pt3Co over the 4.9 nm Pt3Co increased, owing to better stability of the 8.1 nm catalyst. The electron microprobe analysis (EMPA) of the decayed membrane-electrode assembly (MEA) showed that the amount of Co in the membrane was lower for the larger particles, and the platinum loss into the membrane also decreased with increasing particle size. This suggests that the higher initial performance at high currents with 8.1 nm Pt3Co could be due to lower contamination of the ionomer in the electrode. Furthermore, lower loss of Co from the catalyst with increased particle size could be one of the factors contributing to the stability of ECA and mass activity of electrodes with larger cathode catalyst particles. To delineate the impact of particle size and alloy effects, these results are compared with prior work from our research group on size effects of pure platinum catalysts. The impact of PEMFC operating conditions, including upper potential, relative humidity, and temperature on the alloy catalyst decay trends, along with the EMPA analysis of the decayed MEAs, are reported.« less

  19. Minimizing resputtering of Pt-coated microspheres in a batch magnetron sputtering process

    SciTech Connect (OSTI)

    Plake, A.L.

    1981-07-10

    Preventing DT loss from glass microspheres being smoothly coated with PT is needed during fabrication of laser fusion targets. Evidence indicates that the increase of substrate temperature due to resputtering will cause DT loss. Resputtering will prevent a smooth and uniform coating on these glass microspheres (140 ..mu..m in diameter). This paper reviews the method that was developed to find a set of coating conditions to minimize the DT loss, and still be able to produce thick smooth Pt coated glass microspheres.

  20. Pt-free, Perovskite-based Lean NOx Trap Catalysts | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Pt-free, Perovskite-based Lean NOx Trap Catalysts Pt-free, Perovskite-based Lean NOx Trap Catalysts Perovskite-based lean NOx catalysts shown to achieve comparable NOx reduction performance as commercial platinum based counterpart deer10_qi.pdf (1.8 MB) More Documents & Publications Catalyst Design for Urea-less Passive Ammonia SCR Lean-Burn SIDI Aftertreatment System Emissions Control for Lean Gasoline Engines Vehicle Technologies Office Merit Review 2015: Metal Oxide Nano-Array Catalysts

  1. {beta} decay spectroscopy of {sup 192}Pt and the nature of 0{sup +} excitations.

    SciTech Connect (OSTI)

    McCutchan, E. A.; Casten, R. F.; Werner, V.; Winkler, R.; Cakirli, R. B.; Gurdal, G.; Liang, X.; Williams, E.; Physics; Yale Univ.; Istanbul Univ.; Clark Univ.; Univ.of Paisley

    2008-07-01

    Excited states in {sup 192}Pt were populated in {beta}{sup +}/{epsilon} decay and studied through off-beam {gamma}-ray spectroscopy. New coincidence data give no support for several reported low-energy, low-spin states proposed in {beta} decay and lead to a substantially revised level scheme. The structure of {sup 192}Pt is discussed in terms of both single-space IBA-1 calculations and two-space IBA calculations with configuration mixing. Both models together suggest that it is the perhaps the 04{sup +} state that corresponds to an intruder excitation, resulting from the excitation of a pair of protons across the Z=82 closed shell.

  2. Supersymmetric analysis of the Dirac-Weyl operator within PT symmetry

    SciTech Connect (OSTI)

    Ye?ilta?, zlem

    2014-08-15

    Two-dimensional effective Hamiltonian for a massless Dirac electron interacting with a hyperbolic magnetic field is discussed within PT symmetry. Factorization method and polynomial procedures are used to solve Dirac equation for the constant Fermi velocity and the effective potential which is complex Scarf II potential. The more general effective Scarf II potential models are also obtained within pseudo-supersymmetry. Finally, an extension of Panella and Roy's work [Phys. Lett. A 376, 25802583 (2012)] to the both PT symmetric and real Scarf II partner potentials is given using the position dependent Fermi velocity.

  3. Magnetic interactions in NiO at ultrahigh pressure

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Potapkin, Vasily; Dubrovinsky, Leonid; Sergueev, I.; Ekholm, M.; Kantor, Innokenty; Bessas, D.; Bykova, E.; Prakapenka, V.; Hermann, Raphael P.; Rueffer, Rudolf; et al

    2016-05-24

    Here, magnetic properties of NiO have been studied in the multimegabar pressure range by nuclear forward scattering of synchrotron radiation using the 67.4 keV M ssbauer transition of 61Ni. The observed magnetic hyperfine splitting confirms the antiferromagnetic state of NiO up to 280 GPa, the highest pressure where magnetism has been observed so far, in any material. Remarkably, the hyperfine field increases from 8.47 T at ambient pressure to ~24 T at the highest pressure, ruling out the possibility of a magnetic collapse. A joint x-ray diffraction and extended x-ray-absorption fine structure investigation reveals that NiO remains in a distortedmore » sodium chloride structure in the entire studied pressure range. Ab initio calculations support the experimental observations, and further indicate a complete absence of Mott transition in NiO up to at least 280 GPa.« less

  4. Photosensitivity of the Ni-n-GaAs Schottky barriers

    SciTech Connect (OSTI)

    Melebaev, D.; Melebaeva, G. D.; Rud', V. Yu. Rud', Yu. V.

    2009-01-15

    The method of chemical deposition is used to form the structures with the Ni-n-GaAs Schottky barrier. The thickness of the Ni layers with a specular outer surface was varied within the range of 150-220 A. It was experimentally observed for the first time that photosensitivity of the obtained barriers with the semitransparent Ni layers illuminated is practically absent in the Fowler region of the spectrum at hv = 0.9-1.5 eV. This circumstance is related mainly to the fact that, in this case, the Ni layer side of the structure was illuminated, and radiation with the photon energy hv < 1.3 eV was effectively reflected from the nickel surface. It is established that the developed Ni-n-GaAs structures can be used as high-efficiency wide-band photoconverters of both visible and ultraviolet radiation.

  5. MgO-Supported Cluster Catalysts with Pt-Ru Interactions Prepared from Pt3Ru6(CO)21(u3-H)(u-H)3

    SciTech Connect (OSTI)

    Chotisuwan,S.; Wittapyakun, J.; Lobo-Lapidus, R.; Gates, B.

    2007-01-01

    Bimetallic MgO-supported catalysts were prepared by adsorption of Pt{sub 3}Ru{sub 6}(CO){sub 21}({mu}{sub 3}-H)({mu}-H){sub 3} on porous MgO. Characterization of the supported clusters by infrared (IR) spectroscopy showed that the adsorbed species were still in the form of metal carbonyls. The supported clusters were decarbonylated by treatment in flowing helium at 300 C, as shown by IR and extended X-ray absorption fine structure (EXAFS) data, and the resulting supported PtRu clusters were shown by EXAFS spectroscopy to have metal frames that retained Pt-Ru bonds but were slightly restructured relative to those of the precursor; the average cluster size was almost unchanged as a result of the decarbonylation. These are among the smallest reported bimetallic clusters of group-8 metals. The decarbonylated sample catalyzed ethylene hydrogenation with an activity similar to that reported previously for {gamma}-Al{sub 2}O{sub 3}-supported clusters prepared in nearly the same way and having nearly the same structure. Both samples were also active for n-butane hydrogenolysis, with the MgO-supported catalyst being more active than the {gamma}-Al{sub 2}O{sub 3}-supported catalyst.

  6. Effects of Cr and Ni on Interdiffusion and Reaction between U and Fe-Cr-Ni Alloys

    SciTech Connect (OSTI)

    K. Huang; Y. Park; L. Zhou; K.R. Coffey; Y.H. Sohn; B.H. Sencer; J. R. Kennedy

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe–15 wt.%Cr or Fe–15 wt.%Cr–15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe–Cr–Ni exhibited a similar temperature dependence, while the U vs. Fe–Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases – lower growth rate at lower temperature but higher growth rate at higher temperature.

  7. Immobilizing Highly Catalytically Active Pt Nanoparticles inside the Pores of Metal-Organic Framework: A Double Solvents Approach

    SciTech Connect (OSTI)

    Aijaz, Arshad; Karkamkar, Abhijeet J.; Choi, Young Joon; Tsumori, Nobuko; Ronnebro, Ewa; Autrey, Thomas; Shioyama, Hiroshi; Xu, Qiang

    2012-08-29

    Ultrafine Pt nanoparticles were successfully immobilized inside the pores of a metal-organic framework MIL-101 without deposition of Pt nanoparticles on the external surfaces of framework by using a 'double solvents' method. The resulting Pt@MIL-101 composites with different Pt loadings represent the first highly active MOF-immobilized metal nanocatalysts for catalytic reactions in all three phases: liquid-phase ammonia borane hydrolysis; solid-phase ammonia borane thermal dehy-drogenation and gas-phase CO oxidation. The observed excellent catalytic performances are at-tributed to the small Pt nanoparticles within the pores of MIL-101. 'We are thankful to AIST and METI for financial support. TA & AK are thankful for support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. PNNL is operated by Battelle.'

  8. Study of perpendicular anisotropy L1{sub 0}-FePt pseudo spin valves using a micromagnetic trilayer model

    SciTech Connect (OSTI)

    Ho, Pin; Evans, Richard F. L.; Chantrell, Roy W.; Han, Guchang; Chow, Gan-Moog; Chen, Jingsheng

    2015-06-07

    A trilayer micromagnetic model based on the Landau-Lifshitz-Bloch equation of motion is utilized to study the properties of L1{sub 0}-FePt/TiN/L1{sub 0}-FePt pseudo spin valves (PSVs) in direct comparison with experiment. Theoretical studies give an insight on the crystallographic texture, magnetic properties, reversal behavior, interlayer coupling effects, and magneto-transport properties of the PSVs, in particular, with varying thickness of the top L1{sub 0}-FePt and TiN spacer. We show that morphological changes in the FePt layers, induced by varying the FePt layer thickness, lead to different hysteresis behaviors of the samples, caused by changes in the interlayer and intralayer exchange couplings. Such effects are important for the optimization of the PSVs due to the relationship between the magnetic properties, domain structures, and the magnetoresistance of the device.

  9. Comparative study of the alloying effect on the initial oxidation of Cu-Au(100) and Cu-Pt(100)

    SciTech Connect (OSTI)

    Luo, Langli; Zhou, Guangwen; Kang, Yihong; Yang, Judith C.; Su, Dong; Stach, Eric A.

    2014-03-24

    Using in situ transmission electron microscopy, we show that the oxidation of the Cu-Au(100) results in the formation of Cu{sub 2}O islands that deeply embed into the Cu-Au substrate while the oxidation of the Cu-Pt(100) leads to the formation of Cu{sub 2}O islands that highly protrude above the Cu-Pt substrate. Their difference is attributed to the different mobilities of Pt and Au in the Cu base alloys for which the sluggish mobility of Pt in Cu results in trapped Pt atoms at the oxide/alloy interface while the faster mobility of Au in Cu leads to enhanced rehomogenization of the alloy composition.

  10. Selectivity loss of Pt/CeO{sub 2} PROX catalysts at low CO concentrations: mechanism and active site study.

    SciTech Connect (OSTI)

    Polster, C. S.; Zhang, R.; Cyb, M. T.; Miller, J. T.; Baertsch, C. D.

    2010-07-01

    CO and H{sub 2} oxidation were studied over a series of Pt/CeO{sub 2} catalysts with differing Pt loadings and dispersions. Kinetic rate analysis confirms the presence of dual Langmuir-Hinshelwood (L-H) and Mars and van Krevelen (M-vK) pathways and is used to explain the loss in CO oxidation selectivity at low CO concentrations. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) shows the strong CO coverage dependence on both CO and O{sub 2} concentrations and explains the transition from L-H to M-vK reaction character. Redox site measurements are performed on Pt/CeO{sub 2} catalysts by anaerobic titrations under conditions where the M-vK pathway dominates the reaction rate. Similar redox site densities per interfacial Pt atom suggest that interfacial Pt-O-Ce sites are responsible for M-vK redox activity.

  11. The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa

    SciTech Connect (OSTI)

    zduran, Mustafa; Turgut, Kemal; Arikan, Nihat; ?yigr, Ahmet; Candan, Abdullah

    2014-10-06

    We computed the electronic structure, elastic moduli, vibrational properties, and Ni{sub 2}TiGa and Ni{sub 2}ScGa alloys in the cubic L2{sub 1} structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C{sub 11}, C{sub 12} and C{sub 44}. We calculated elastic constants in L2{sub 1} structure for Ni{sub 2}TiGa and Ni{sub 2}ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni{sub 2}TiGa, Ni 3d states and Sc 3d states for Ni{sub 2}ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni{sub 2}TiGa, 0.76 states/eV Cell for Ni{sub 2}ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2{sub 1} phase is unstable since the phonon calculations have imagine modes.

  12. Can Ni phosphides become viable hydroprocessing catalysts?

    SciTech Connect (OSTI)

    Soled, S.; Miseo, S.; Baumgartner, J.; Guzman, J.; Bolin, T.; Meyer, R.

    2015-05-15

    We prepared higher surface area nickel phosphides than are normally found by reducing nickel phosphate. To do this, we hydrothermally synthesized Ni hydroxy phosphite precursors with low levels of molybdenum substitution. The molybdenum substitution increases the surface area of these precursors. During pretreatment in a sulfiding atmosphere (such as H2S/H2) dispersed islands of MoS2 segregate from the precursor and provide a pathway for H2 dissociation that allows reduction of the phosphite precursor to nickel phosphide at substantially lower temperatures than in the absence of MoS2. The results reported here show that to create nickel phosphides with comparable activity to conventional supported sulfide catalysts, one would have to synthesize the phosphide with surface areas exceeding 400 m2/g (i.e. with nanoparticles less than 30 Å in lateral dimension).

  13. Ni/metal hydride secondary element

    DOE Patents [OSTI]

    Bauerlein, Peter

    2005-04-19

    A Ni/metal hydride secondary element having a positive nickel hydroxide electrode, a negative electrode having a hydrogen storage alloy, and an alkaline electrolyte, the positive electrode, provided with a three-dimensional metallic conductive structure, also contains an aluminum compound which is soluble in the electrolyte, in addition to nickel hydroxide and cobalt oxide. The aluminum compound is aluminum hydroxide and/or aluminum oxide, and the mass of the aluminum compound which is present in the positive bulk material mixture is 0.1 to 2% by weight relative to the mass of the nickel hydroxide which is present. In combination with aluminum hydroxide or aluminum oxide, the positive electrode further contains lanthanoid oxidic compounds Y.sub.2 O.sub.3, La.sub.2 O.sub.3 and Ca(OH).sub.2, as well as mixtures of these compounds.

  14. Spectroscopic study of tetradecyltrimethylammonium bromide Pt-C14TAB nanoparticles: Structure and Stability

    SciTech Connect (OSTI)

    Borodko, Y.; Jones, L.; Frei, H.; Somorjai, G.

    2009-01-09

    The vibrational spectra of platinum nanoparticles (12 nm) capped with tetradecyltrimethylammonium bromide, C{sub 14}TAB, were investigated by Fourier transform infrared (FTIR) spectroscopy. We have shown that the thermal decay of Pt-C{sub 14}TAB nanoparticles in N{sub 2}, H{sub 2} and O{sub 2} atmospheres leads to the release of hydrocarbon chain of surfactant and the formation of strongly bonded layer of ammonium cations on the platinum surface. The platinum atoms accessible to CO chemisorptions were not reducible by hydrogen in the temperature ranging from 30 C to 200 C. A FTIR spectrum of C{sub 14}TAB adsorbed on Pt nanoparticles dramatically perturbed as compared with pure C{sub 14}TAB. New intense and broad bands centered at 1450 cm{sup -1} and 760 cm{sup -1} are making their appearance in Pt-C{sub 14}TAB. It may be speculated, that new bands are result of coupling between conducting electrons of Pt and molecular vibrations of adsorbed C{sub 14}TAB and as a consequence specific vibrational modes of ammonium cation transformed into electron-vibrational modes.

  15. Various scattering properties of a new PT-symmetric non-Hermitian potential

    SciTech Connect (OSTI)

    Ghatak, Ananya; Mandal, Raka Dona Ray; Mandal, Bhabani Prasad

    2013-09-15

    We complexify a 1-d potential V(x)=V{sub 0}cosh{sup 2}?(tanh[(x??d)/d]+tanh(?)){sup 2} which exhibits bound, reflecting and free states to study various properties of a non-Hermitian system. This potential turns out a PT-symmetric non-Hermitian potential when one of the parameters (?,d) becomes imaginary. For the case of ??i?, we have an entire real bound state spectrum. Explicit scattering states are constructed to show reciprocity at certain discrete values of energy even though the potential is not parity symmetric. Coexistence of deep energy minima of transmissivity with the multiple spectral singularities (MSS) is observed. We further show that this potential becomes invisible from the left (or right) at certain discrete energies. The penetrating states in the other case (d?id) are always reciprocal even though it is PT-invariant and no spectral singularity (SS) is present in this case. The presence of MSS and reflectionlessness is also discussed for the free states in the later case. -- Highlights: Existence of multiple spectral singularities (MSS) in PT-symmetric non-Hermitian system is shown. Reciprocity is restored at discrete positive energies even for parity non-invariant complex system. Co-existence of MSS with deep energy minima of transitivity is obtained. Possibilities of both unidirectional and bidirectional invisibility are explored for a non-Hermitian system. Penetrating states are shown to be reciprocal for all energies for PT-symmetric system.

  16. Reducing the ordering temperature of CoPt nanoparticles by B additive

    SciTech Connect (OSTI)

    Khemjeen, Yutthaya; Pinitsoontorn, Supree Chompoosor, Apiwat; Maensiri, Santi

    2014-08-07

    We reported the effect of boron addition on magnetic properties and structure of CoPt nanoparticles prepared by a polyol method. The magnetic property measurement showed that the CoPt-B sample exhibited a much larger coercivity compared to the sample without B additive at the same annealing temperature. Transmission electron microscopy and energy dispersive X-ray spectroscopy revealed that the average particle size was about 2?nm for the as-synthesized sample with the ratio of Co and Pt close to 1:1. After annealing, the particle sizes increased but the composition was maintained. The phase transformation of the nanoparticles versus temperature was investigated using a combination of X-ray diffraction and in-situ X-ray absorption analysis. It was shown that the phase transition temperature at which the nanoparticles change from the disordered A1 phase to the ordered L1{sub 0} phase occurs at temperature of 600?C. We concluded that boron additives could reduce the ordering temperature of CoPt of about 100?C.

  17. The fabrication of foam-like 3D mesoporous NiO-Ni as anode for high performance Li-ion batteries

    SciTech Connect (OSTI)

    Huang, Peng; Zhang, Xin; Wei, Jumeng; Pan, Jiaqi; Sheng, Yingzhou; Feng, Boxue

    2015-03-15

    Graphical abstract: Foam-like 3 dimensional (3D) mesoporous NiO on 3D micro-porous Ni was fabricated. - Highlights: We prepare NiO-Ni foam composite via hydrothermal etching and subsequent annealing. The NiO exhibits novel foam-like 3D mesoporous architecture. The NiO-Ni anode shows good cycle stability. - Abstract: Foam-like three dimensional mesoporous NiO on Ni foam was fabricated via facile hydrothermal etching and subsequent annealing treatment. The porous NiO consists of a large number of nanosheets with mean thickness about 50 nm, among which a large number of mesoscopic pores with size ranges from 100 nm to 1 ?m distribute. The electrochemical performance of the as-prepared NiO-Ni as anode for lithium ion battery was studied by conventional charge/discharge test, which shows excellent cycle stability and rate capability. It exhibits initial discharge and charge capacities of 979 and 707 mA h g{sup ?1} at a charge/discharge rate of 0.7 C, which maintain of 747 and 738 mA h g{sup ?1} after 100 cycles. Even after 60 cycles at various rates from 0.06 to 14 C, the 10th discharge and charge capacities of the NiO-Ni electrode can revert to 699 and 683 mA h g{sup ?1} when lowering the charge/discharge rate to 0.06 C.

  18. Impact of solvent for individual steps of phenol hydrodeoxygenation with Pd/C and HZSM-5 as catalysts

    SciTech Connect (OSTI)

    He, Jiayue; Zhao, Chen; Lercher, Johannes A.

    2014-01-01

    Impacts of water, methanol, and hexadecane solvents on the individual steps of phenol hydrodeoxygenation are investigated over Pd/C and HZSM-5 catalyst components at 473 Kin presence of H-2. Hydrodeoxygenation of phenol to cyclohexane includes four individual steps of phenol hydrogenation to cyclohexanone on Pd/C, cyclohexanone hydrogenation to cyclohexanol on Pd/C, cyclohexanol dehydration to cyclohexene on HZSM-5, and cyclohexene hydrogenation to cyclohexane on Pd/C. Individual phenol and cyclohexanone hydrogenation rates are much lower in methanol and hexadecane than in water, while rates of cyclohexanol dehydration and cyclohexene hydrogenation are similar in three solvents. The slow rate in methanol is due to the strong solvation of reactants and the adsorption of methanol on Pd, as well as to the reaction between methanol and the cyclohexanone intermediate. The low solubility of phenol and strong interaction of hexadecane with Pd lead to the slow rate in hexadecane. The apparent activation energies for hydrogenation follow the order E-a phenol > E-a cyclonexanone > E-a cyclohexene, and the sequences of individual reaction rates are reverse in three solvents. The dehydration rates (1.1-1.8 x 10(3) mol mol(BAS)(-1) h(-1))and apparent activation energies (115-124 kJ mol(-1)) are comparable in three solvents. In situ liquid-phase IR spectroscopy shows the rates consistent with kinetics derived from chromatographic evidence in the aqueous phase and verifies that hydrogenation of phenol and cyclohexanone follows reaction orders of 1.0 and 0.55 over Pd/C, respectively. Conversion of cyclohexanol with HZSM-5 shows first-order dependence in approaching the dehydration-hydration equilibrium in the aqueous phase.

  19. Antiferromagnetic Kondo lattice in the layered compound CePd1xBi? and comparison to the superconductor LaPd1xBi?

    SciTech Connect (OSTI)

    Han, Fei; Wan, Xiangang; Phelan, Daniel; Stoumpos, Constantinos C.; Sturza, Mihai; Malliakas, Christos D.; Li, Qing'an; Han, Tian-Heng; Zhao, Qingbiao; Chung, Duck Young; Kanatzidis, Mercouri G.

    2015-07-13

    The layered compound CePd1xBi? with the tetragonal ZrCuSi?-type structure was obtained from excess Bi flux. Magnetic susceptibility data of CePd1xBi? show an antiferromagnetic ordering below 6 K and are anisotropic along the c axis and the ab plane. The anisotropy is attributed to crystal-electric-field (CEF) effects and a CEF model which is able to describe the susceptibility data is given. An enhanced Sommerfeld coefficient ? of 0.191 J mol Ce? K? obtained from specific-heat measurement suggests a moderate Kondo effect in CePd1xBi?. Other than the antiferromagnetic peak at 6 K, the resistivity curve shows a shoulderlike behavior around 75 K which could be attributed to the interplay between Kondo and CEF effects. Magnetoresistance and Hall-effect measurements suggest that the interplay reconstructs the Fermi-surface topology of CePd1xBi? around 75 K. Electronic structure calculations reveal that the Pd vacancies are important to the magnetic structure and enhance the CEF effects which quench the orbital moment of Ce at low temperatures.

  20. Graphene Monolayer Rotation on Ni(111) Facilities Bilayer Graphene Growth

    SciTech Connect (OSTI)

    Batzill M.; Sutter P.; Dahal, A.; Addou, R.

    2012-06-11

    Synthesis of bilayer graphene by chemical vapor deposition is of importance for graphene-based field effect devices. Here, we demonstrate that bilayer graphene preferentially grows by carbon-segregation under graphene sheets that are rotated relative to a Ni(111) substrate. Rotated graphene monolayer films can be synthesized at growth temperatures above 650 C on a Ni(111) thin-film. The segregated second graphene layer is in registry with the Ni(111) substrate and this suppresses further C-segregation, effectively self-limiting graphene formation to two layers.

  1. Nondestructive evaluation of Ni-Ti shape memory alloy

    SciTech Connect (OSTI)

    Meir, S.; Gordon, S.; Karsh, M.; Ayers, R.; Olson, D. L.; Wiezman, A.

    2011-06-23

    The nondestructive evaluation of nickel titanium (Ni-Ti) alloys for applications such as heat treatment for biomaterials applications (dental) and welding was investigated. Ni-Ti alloys and its ternary alloys are valued for mechanical properties in addition to the shape memory effect. Two analytical approaches were perused in this work. Assessment of the microstructure of the alloy that determines the martensitic start temperature (Ms) of Ni-Ti alloy as a function of heat treatment, and secondly, an attempt to evaluate a Friction Stir Welding, which involves thermo-mechanical processing of the alloy.

  2. Application of cluster-plus-glue-atom model to barrierless CuNiTi and CuNiTa films

    SciTech Connect (OSTI)

    Li, Xiaona, E-mail: lixiaona@dlut.edu.cn; Ding, Jianxin; Wang, Miao; Dong, Chuang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Chu, Jinn P. [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China)

    2014-11-01

    To improve the thermal stability of copper and avoid its diffusion into surrounding dielectrics or interfacial reactions with them, the authors applied the cluster-plus-glue-atom model to investigate barrierless CuNiM (M?=?Ti or Ta) seed layers. The dissolution of the third element (Ti or Ta) in the Cu lattice with the aid of Ni significantly improved the thermal stability of the Cu seed layer. The appropriate M/Ni (M?=?Ti or Ta) ratio was selected to obtain a low resistivity: the resistivity was as low as 2.5??? cm for the (Ti{sub 1.5/13.5}Ni{sub 12/13.5}){sub 0.3}Cu{sub 99.7} film and 2.8??? cm for the (Ta{sub 1.1/13.1}Ni{sub 12/13.1}){sub 0.4}Cu{sub 99.6} film after annealing at 500?C for 1?h. After annealing at 500?C for 40?h, the two films remained stable without forming a Cu{sub 3}Si compound. The authors confirmed that the range of applications of the cluster-plus-glue-atom model could be extended. Therefore, a third element M with negative enthalpies of mixing with both Cu and Ni could be selected, under the premise that the mixing enthalpy of MNi is more negative than that of MCu.

  3. Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy

    SciTech Connect (OSTI)

    Pramanick, S.; Giri, S.; Majumdar, S.; Chatterjee, S.

    2014-09-15

    Present work reports on the observation of large magnetoresistance (??30% at 80 kOe) and magnetocaloric effect (?12?Jkg{sup ?1}K{sup ?1} for 050 kOe) near room temperature (?290?K) on the Ni-excess ferromagnetic shape memory alloy Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56}. The sample can be thought of being derived from the parent Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56} it is found to be optimum (288?K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.

  4. The influence of nano-architectured CeOx supports in RhPd/CeO₂ for the catalytic ethanol steam reforming reaction

    SciTech Connect (OSTI)

    Divins, N. J.; Senanayake, S. D.; Casanovas, A.; Xu, W.; Trovarelli, A.; Llorca, J.

    2015-01-19

    The ethanol steam reforming (ESR) reaction has been tested over RhPd supported on polycrystalline ceria in comparison to structured supports composed of nanoshaped CeO₂ cubes and CeO₂ rods tailored towards the production of hydrogen. At 650-700 K the hydrogen yield follows the trend RhPd/CeO₂-cubes > RhPd/CeO₂ -rods > RhPd/CeO₂- polycrystalline, whereas at temperatures higher than 800 K the catalytic performance of all samples is similar and close to the thermodynamic equilibrium. The improved performance of RhPd/CeO₂-cubes and RhPd/CeO₂ -rods for ESR at low temperature is mainly ascribed to higher water-gas shift activity and a strong interaction between the bimetallic - oxide support interaction. STEM analysis shows the existence of RhPd alloyed nanoparticles in all samples, with no apparent relationship between ESR performance and RhPd particle size. X-ray diffraction under operating conditions shows metal reorganization on {100} and {110} ceria crystallographic planes during catalyst activation and ESR, but not on {111} ceria crystallographic planes. The RhPd reconstructing and tuned activation over ceria nanocubes and nanorods is considered the main reason for better catalytic activity with respect to conventional catalysts based on polycrystalline ceria

  5. The influence of nano-architectured CeOx supports in RhPd/CeO₂ for the catalytic ethanol steam reforming reaction

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Divins, N. J.; Senanayake, S. D.; Casanovas, A.; Xu, W.; Trovarelli, A.; Llorca, J.

    2015-01-19

    The ethanol steam reforming (ESR) reaction has been tested over RhPd supported on polycrystalline ceria in comparison to structured supports composed of nanoshaped CeO₂ cubes and CeO₂ rods tailored towards the production of hydrogen. At 650-700 K the hydrogen yield follows the trend RhPd/CeO₂-cubes > RhPd/CeO₂ -rods > RhPd/CeO₂- polycrystalline, whereas at temperatures higher than 800 K the catalytic performance of all samples is similar and close to the thermodynamic equilibrium. The improved performance of RhPd/CeO₂-cubes and RhPd/CeO₂ -rods for ESR at low temperature is mainly ascribed to higher water-gas shift activity and a strong interaction between the bimetallic -more » oxide support interaction. STEM analysis shows the existence of RhPd alloyed nanoparticles in all samples, with no apparent relationship between ESR performance and RhPd particle size. X-ray diffraction under operating conditions shows metal reorganization on {100} and {110} ceria crystallographic planes during catalyst activation and ESR, but not on {111} ceria crystallographic planes. The RhPd reconstructing and tuned activation over ceria nanocubes and nanorods is considered the main reason for better catalytic activity with respect to conventional catalysts based on polycrystalline ceria« less

  6. Intrinsic state lifetimes in {sup 103}Pd and {sup 106,107}Cd

    SciTech Connect (OSTI)

    Ashley, S. F.; Thomas, N. J.; Regan, P. H.; Gelletly, W.; Andgren, K.; McCutchan, E. A.; Casten, R. F.; Plettner, C.; Vinson, J.; Werner, V.; Williams, E.; Zamfir, N. V.; Amon, L.; Cakirli, R. B.; Clark, R. M.; Guerdal, G.; Keyes, K. L.; Papenberg, A.; Meyer, D. A.; Erduran, M. N.

    2007-12-15

    The mean-lifetimes, {tau}, of various medium-spin excited states in {sup 103}Pd and {sup 106,107}Cd have been deduced using the Recoil Distance Doppler Shift technique and the Differential Decay Curve Method. In {sup 106}Cd, the mean-lifetimes of the I{sup {pi}}=12{sup +} state at E{sub x}=5418 keV and the I{sup {pi}}=11{sup -} state at E{sub x}=4324 keV have been deduced as 11.4(17)ps and 8.2(7)ps, respectively. The associated {beta}{sub 2} deformation within the axially-symmetric deformed rotor model for these states are 0.14(1) and 0.14(1), respectively. The {beta}{sub 2} deformation of 0.14(1) for the I{sup {pi}}=12{sup +} state in {sup 106}Cd compares with a predicted {beta}{sub 2} value from total Routhian surface (TRS) calculations of 0.17. In addition, the mean-lifetimes of the yrast I{sup {pi}}=(15/2){sup -} states in {sup 103}Pd (at E{sub x}=1262 keV) and {sup 107}Cd (at E{sub x}=1360 keV) have been deduced to be 31.2(44)ps and 31.4(17)ps, respectively, corresponding to {beta}{sub 2} values of 0.16(1) and 0.12(1) assuming axial symmetry. Agreement with TRS calculations are good for {sup 103}Pd but deviate for that predicted for {sup 107}Cd.

  7. Tunability of exchange bias in Ni@NiO core-shell nanoparticles obtained by sequential layer deposition

    SciTech Connect (OSTI)

    D'Addato, Sergio; Spadaro, Maria Chiara; Luches, Paola; Valeri, Sergio; Grillo, Vincenzo; Rotunno, Enzo; Roldan Gutierrez, Manuel A.; Pennycook, Stephen J.; Ferretti, Anna Maria; Capetti, Elena; Ponti, A.

    2015-01-01

    Films of magnetic Ni@NiO core–shell nanoparticles (NPs, core diameter d ≅ 12 nm, nominal shell thickness variable between 0 and 6.5 nm) obtained with sequential layer deposition were investigated, to gain insight into the relationships between shell thickness/morphology, core-shell interface, and magnetic properties. Different values of NiO shell thickness ts could be obtained while keeping the Ni core size fixed, at variance with conventional oxidation procedures where the oxide shell is grown at the expense of the core. Chemical composition, morphology of the as-produced samples and structural features of the Ni/NiO interface were investigated with x-ray photoelectron spectroscopy and microscopy (scanning electron microscopy, transmission electron microscopy) techniques, and related with results from magnetic measurements obtained with a superconducting quantum interference device. The effect of the shell thickness on the magnetic properties could be studied. The exchange bias (EB) field Hbias is small and almost constant for ts up to 1.6 nm; then it rapidly grows, with no sign of saturation. This behavior is clearly related to the morphology of the top NiO layer, and is mostly due to the thickness dependence of the NiO anisotropy constant. The ability to tune the EB effect by varying the thickness of the last NiO layer represents a step towards the rational design and synthesis of core–shell NPs with desired magnetic properties.

  8. [NiIII(OMe)]-mediated reductive activation of CO2 affording a Ni(κ1-OCO) complex

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chiou, Tzung -Wen; Tseng, Yen -Ming; Lu, Tsai -Te; Weng, Tsu -Chien; Sokaras, Dimosthenes; Ho, Wei -Chieh; Kuo, Ting -Shen; Jang, Ling -Yun; Lee, Jyh -Fu; Liaw, Wen -Feng

    2016-02-24

    Here, carbon dioxide is expected to be employed as an inexpensive and potential feedstock of C1 sources for the mass production of valuable chemicals and fuel. Versatile chemical transformations of CO2, i.e. insertion of CO2 producing bicarbonate/acetate/formate, cleavage of CO2 yielding μ-CO/μ-oxo transition-metal complexes, and electrocatalytic reduction of CO2 affording CO/HCOOH/CH3OH/CH4/C2H4/oxalate were well documented. Herein, we report a novel pathway for the reductive activation of CO2 by the [NiIII(OMe)(P(C6H3-3-SiMe3-2-S)3)]– complex, yielding the [NiIII(κ1-OCO˙–)(P(C6H3-3-SiMe3-2-S)3)]– complex. The formation of this unusual NiIII(κ1-OCO˙–) complex was characterized by single-crystal X-ray diffraction, EPR, IR, SQUID, Ni/S K-edge X-ray absorption spectroscopy, and Ni valence-to-core X-ray emissionmore » spectroscopy. The inertness of the analogous complexes [NiIII(SPh)], [NiII(CO)], and [NiII(N2H4)] toward CO2, in contrast, demonstrates that the ionic [NiIII(OMe)] core attracts the binding of weak σ-donor CO2 and triggers the subsequent reduction of CO2 by the nucleophilic [OMe]– in the immediate vicinity. This metal–ligand cooperative activation of CO2 may open a novel pathway promoting the subsequent incorporation of CO2 in the buildup of functionalized products.« less

  9. Travelling fronts of the CO oxidation on Pd(111) with coverage-dependent diffusion

    SciTech Connect (OSTI)

    Cisternas, Jaime, E-mail: jecisternas@miuandes.cl [Facultad de Ingeniera y Ciencias Aplicadas, Universidad de los Andes, Monseor Alvaro del Portillo 12455, Las Condes, Santiago (Chile); Karpitschka, Stefan [Physics of Fluids, University of Twente, Drienerlolaan 5, 7522 NB Enschede (Netherlands); Wehner, Stefan [Institut fr Integrierte Naturwissenschaften - Physik, Universitt Koblenz-Landau, 56070 Koblenz (Germany)

    2014-10-28

    In this work, we study a surface reaction on Pd(111) crystals under ultra-high-vacuum conditions that can be modeled by two coupled reaction-diffusion equations. In the bistable regime, the reaction exhibits travelling fronts that can be observed experimentally using photo electron emission microscopy. The spatial profile of the fronts reveals a coverage-dependent diffusivity for one of the species. We propose a method to solve the nonlinear eigenvalue problem and compute the direction and the speed of the fronts based on a geometrical construction in phase-space. This method successfully captures the dependence of the speed on control parameters and diffusivities.

  10. An over view of excess heat production in the D/Pd system at SRI

    SciTech Connect (OSTI)

    Crouch-Baker, S.; Hauser, A.; Jevtic, N.

    1995-12-01

    Experiments have been undertaken to demonstrate and quantify the rate of heat production of palladium cathodes loaded electrochemically with deuterium. Excess heat has been observed in these experiments at SRI on more than 40 occasions in accurate and stable isothermal mass flow calorimeters. The excess power appears to be correlated with at least three criteria: the degree of deuterium loading (specified as the atomic ratio D/Pd), the Lime for which high loading is maintained, the interfacial current density. The correlation between excess heat production and these three variables will be discussed. In addition, the results of experiments designed to search for further products of the heat producing reaction will he reported.

  11. Cubic to Tetragonal Phase Transformation in Cold-Compressed Pd Nanocubes

    SciTech Connect (OSTI)

    Guo, Q.X.; Zhao, Y.S.; Mao, W.L.; Wang, Z.W.; Xiong, Y.J.; Xia, Y.N.; /Los Alamos /SLAC /Cornell U., LNS /Washington U., Seattle

    2009-06-09

    Pd nanocubes with an average side length of {approx}10 nm were compressed up to 24.8 GPa in a diamond-anvil cell (DAC). In situ synchrotron X-ray diffraction was used to monitor structural changes, and a face-centered cubic (fcc) to face-centered tetragonal (fct) distortion was observed for the first time. This novel discovery not only provides new insights into the pressure-induced behavior of faceted nanocrystals of palladium and other noble metals but also gives guidance for finding new phases in close-packed metals.

  12. Atomic-scale identification of Pd leaching in nanoparticle catalyzed C–C coupling: Effects of particle surface disorder

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Briggs, Beverly D.; Bedford, Nicholas M.; Seifert, Soenke; Koerner, Hilmar; Ramezani-Dakhel, Hadi; Heinz, Hendrik; Naik, Rajesh R.; Frenkel, Anatoly I.; Knecht, Marc R.

    2015-07-23

    C–C coupling reactions are of great importance in the synthesis of numerous organic compounds, where Pd nanoparticle catalyzed systems represent new materials to efficiently drive these reactions. Despite their pervasive utility, the catalytic mechanism of these particle-based reactions remains highly contested. Herein we present evidence of an atom leaching mechanism for Stille coupling under aqueous conditions using peptide-capped Pd nanoparticles. EXAFS analysis revealed Pd coordination changes in the nanoparticle consistent with Pd atom abstraction, where sizing analysis by SAXS confirmed particle size changes associated with a leaching process. It is likely that recently discovered highly disordered surface Pd atoms aremore » the favored catalytic active sites and are leached during oxidative addition, resulting in smaller particles. Thus, probing the mechanism of nanoparticle-driven C–C coupling reactions through structural analyses provides fundamental information concerning these active sites and their reactivity at the atomic-scale, which can be used to improve catalytic performance to meet important sustainability goals.« less

  13. Atomic-scale identification of Pd leaching in nanoparticle catalyzed C–C coupling: Effects of particle surface disorder

    SciTech Connect (OSTI)

    Briggs, Beverly D.; Bedford, Nicholas M.; Seifert, Soenke; Koerner, Hilmar; Ramezani-Dakhel, Hadi; Heinz, Hendrik; Naik, Rajesh R.; Frenkel, Anatoly I.; Knecht, Marc R.

    2015-07-23

    C–C coupling reactions are of great importance in the synthesis of numerous organic compounds, where Pd nanoparticle catalyzed systems represent new materials to efficiently drive these reactions. Despite their pervasive utility, the catalytic mechanism of these particle-based reactions remains highly contested. Herein we present evidence of an atom leaching mechanism for Stille coupling under aqueous conditions using peptide-capped Pd nanoparticles. EXAFS analysis revealed Pd coordination changes in the nanoparticle consistent with Pd atom abstraction, where sizing analysis by SAXS confirmed particle size changes associated with a leaching process. It is likely that recently discovered highly disordered surface Pd atoms are the favored catalytic active sites and are leached during oxidative addition, resulting in smaller particles. Thus, probing the mechanism of nanoparticle-driven C–C coupling reactions through structural analyses provides fundamental information concerning these active sites and their reactivity at the atomic-scale, which can be used to improve catalytic performance to meet important sustainability goals.

  14. Enhancing low-temperature activity and durability of Pd-based diesel oxidation catalysts using ZrO2 supports

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, Mi -Young; Kyriakidou, Eleni A.; Choi, Jae -Soon; Toops, Todd J.; Binder, Andrew J.; Thomas, Cyril; Schwartz, Viviane; Chen, Jihua; Hensley, Dale K.; Parks, II, James E.

    2016-01-18

    In this study, we investigated the impact of ZrO2 on the performance of palladium-based oxidation catalysts with respect to low-temperature activity, hydrothermal stability, and sulfur tolerance. Pd supported on ZrO2 and SiO2 were synthesized for a comparative study. Additionally, in an attempt to maximize the ZrO2 surface area and improve sulfur tolerance, a Pd support with ZrO2-dispersed onto SiO2 was studied. The physicochemical properties of the catalysts were examined using ICP, N2 sorption, XRD, SEM, TEM, and NH3-, CO2-, and NOx-TPD. The activity of the Pd catalysts were measured from 60 to 600 °C in a flow of 4000 ppmmore » CO, 500 ppm NO, 1000 ppm C3H6, 4% O2, 5% H2O, and Ar balance. The Pd catalysts were evaluated in fresh, sulfated, and hydrothermally aged states. Overall, the ZrO2-containing catalysts showed considerably higher CO and C3H6 oxidation activity than Pd/SiO2 under the reaction conditions studied.« less

  15. Ni(NiO)/single-walled carbon nanotubes composite: Synthesis of electro-deposition, gas sensing property for NO gas and density functional theory calculation

    SciTech Connect (OSTI)

    Li, Li; Zhang, Guo; Chen, Lei; Bi, Hong-Mei; Shi, Ke-Ying

    2013-02-15

    Graphical abstract: The Ni(NiO)/semiconducting single-walled carbon nanotubes composite collected from the cathode after electro-deposition shows a high sensitivity to low-concentration NO gas at room temperature (18 C). Display Omitted Highlights: ? Ni(NiO) nanoparticles were deposited on semiconducting SWCNTs by electro-deposition. ? Ni(NiO)/semiconducting SWCNTs film shows a high sensitivity to NO gas at 18 C. ?Theoretical calculation reveals electron transfer from SWCNTs to NO via Ni. -- Abstract: Single-walled carbon nanotubes which contains metallic SWCNTs (m-SWCNTs) and semiconducting SWCNTs (s-SWCNTs) have been obtained under electric arc discharge. Their separation can be effectively achieved by the electro-deposition method. The Ni(NiO)/s-SWCNTs composite was found on cathode where Ni was partially oxidized to NiO at ambient condition with Ni(NiO) nanoparticles deposited uniformly on the bundles of SWCNTs. These results were confirmed by Raman spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), UVvisNIR and TG characterizations. Furthermore, investigation of the gas sensing property of Ni(NiO)/s-SWCNTs composite film to NO gas at 18 C demonstrated the sensitivity was approximately 5% at the concentration of 97 ppb. Moreover, density functional theory (DFT) calculations were performed to explore the sensing mechanism which suggested the adsorption of NO molecules onto the composite through NNi interaction as well as the proposition of electron transfer mechanisms from SWCNTs to NO via the Ni medium.

  16. Interdiffusion in nanometric Fe/Ni multilayer films

    SciTech Connect (OSTI)

    Liu, JX; Barmak, K

    2015-03-01

    Fe (3.1 nm)/Ni (3.3 nm)](20) multilayer films were prepared by DC magnetron sputtering onto oxidized Si(100) substrates. The Fe and Ni layers were shown to both be face-centered cubic by x-ray diffraction. Interdiffusion of the Fe and Ni layers in the temperature range of 300-430 degrees C was studied by x-ray reflectivity. From the decay of the integral intensity of the superlattice peak, the activation energy and the pre-exponential term for the effective interdiffusion coefficient were determined as to 1.06 +/- 0.07 eV and 5 x 10(-10) cm(2)/s, respectively. The relevance of the measured interdiffusion coefficient to the laboratory timescale synthesis of L1(0) ordered FeNi as a rare-earth free permanent magnet is discussed. (C) 2015 American Vacuum Society.

  17. N"I. L-S- Rad. Mat. DU

    Office of Legacy Management (LM)

    N"I. L-S- Rad. Mat. DU DU (UF4) Enr. U. Norm. U Thorium 34 Ti Alloy Subtotals Commercial ... Nuclear 1063- 570 1,484,083.2 14' Thorium Bridge- port Brass 762 380 -o- -o- 380 ...

  18. Support effects on hydrotreating activity of NiMo catalysts

    SciTech Connect (OSTI)

    Dominguez-Crespo, M.A. Arce-Estrada, E.M.; Torres-Huerta, A.M.

    2007-10-15

    The effect of the gamma alumina particle size on the catalytic activity of NiMoS{sub x} catalysts prepared by precipitation method of aluminum acetate at pH = 10 was studied. The structural characterization of the supports was measured by using XRD, pyridine FTIR-TPD and nitrogen physisorption. NiMo catalysts were characterized during the preparation steps (annealing and sulfidation) using transmission electron microscopy (TEM). Hydrogen TPR studies of the NiMo catalysts were also carried out in order to correlate their hydrogenating properties and their catalytic functionality. Catalytic tests were carried out in a pilot plant at 613, 633 and 653 K temperatures. The results showed that the rate constants of hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatizing (HDA) at 613-653 K decreased in the following order: A > B > C corresponding to the increase of NiMoS particle size associated to these catalysts.

  19. Oxidation-resistant, solution-processed plasmonic Ni nanochain...

    Office of Scientific and Technical Information (OSTI)

    Oxidation-resistant, solution-processed plasmonic Ni nanochain-SiOsub x (x < 2) selective solar thermal absorbers Citation Details In-Document Search Title: Oxidation-resistant, ...

  20. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    SciTech Connect (OSTI)

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy; Narayanan, V. Stephen, A.

    2014-01-28

    Silver-Nickel is the well-known thermally immiscible system that makes them quite complex for the formation of alloy. This kind of alloy can be attained from electrodeposition method. In the present work, AgNi alloy was synthesized by pulsed electrodeposition in a single bath two electrode system with the use of anodic alumina membrane. The prepared AgNi alloy and pure Ag were characterized with X-ray Diffraction (XRD) for structural confirmation, Scanning Electron Microscopy (SEM) for morphological, and magnetic properties by Vibrating Sample Magnetometer, respectively. The X-ray Diffraction study shows the formation of cubic structure for pure Ag. SEM analysis reveals the double dumbbell morphology for AgNi alloy and spherically agglomeration for pure silver. Hysteresis behaviour from VSM measurement indicates that the AgNi alloy have good ferro-magnetic properties.