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. Preparation of PtNi Nanoparticles for the Electrocatalytic Oxidation of Methanol

    E-Print Network [OSTI]

    Deivaraj, T.C.

    Carbon supported PtNi nanoparticles were prepared by hydrazine reduction of Pt and Ni precursor salts under different conditions, namely by conventional heating (PtNi-1), by prolonged reaction at room temperature (PtNi-2) ...

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

    SciTech Connect (OSTI)

    Mun, Bongjin Simon; Lee, Choongman; Stamenkovic, Vojislav; Markovic, Nenad M.; Ross Jr., Philip N.

    2005-05-11

    The origin of surface core-level shift (SCLS) of Pd thin films on Pt(111) substrate is investigated. At sub-monolayer coverage of Pd thin films, the splitting of Pd 3d core level peaks indicate the contribution of both initial and final-state of photo-ionization processes while there is almost no change on valence band (VB) spectra. When the coverage of Pd reaches to single monolayer, the final-state relaxation effect on the Pd 3d vanishes and only the initial-state effect, a negative SCLS, is present. Also, the VB spectrum at Pd monolayer films shows a clear band narrowing, that is the origin of the negative SCLS at monolayer coverage. As the Pd coverage is increased to more than monolayer thickness, the Pd 3d peaks start to show the surface layer contribution from second and third layers, positive SCLS, and the VB spectrum shows even narrower band width, possibly due to the formation of surface states and strained effect of Pd adlayers on top of the first pseudomorphic layer.

  5. 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.

  6. 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

  7. 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, 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 0.1more »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?¹ Pt, as compared to that of commercially available Pt nanoparticles (0.107 mA ?g?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 Pd?Ru@Pt electrocatalyst represents a substantial reduction in the amount of Pt consumption and raw material cost.« less

  8. 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 0.1more »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?¹ Pt, as compared to that of commercially available Pt nanoparticles (0.107 mA ?g?¹ 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

  9. 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 [National Chiao Tung Univ., Hsin-chu (Taiwan); Hsieh, Yu-Chi [Brookhaven National Lab. (BNL), Upton, NY (United States); Chang, Li-Chung [National Chiao Tung Univ., Hsin-chu (Taiwan); Wu, Pu-Wei [National Chiao Tung Univ., Hsin-chu (Taiwan); Lee, Jyh-Fu [National Synchrotron Radiation Research Center, Hsin-chu (Taiwan)

    2015-03-01

    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?¹ Pt, as compared to that of commercially available Pt nanoparticles (0.107 mA ?g?¹ 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.

  10. 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.

  11. 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.

  12. High Performance Plasma Sputtered PdPt Fuel Cell Electrodes with Ultra Low Loading

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    fuel cells currently used in cars have a resource efficiency of 1 or 2 kW gPt -1 . The high amount of platinum makes commercial fuel cells reliable but the resource efficiency is far too low to provideHigh Performance Plasma Sputtered PdPt Fuel Cell Electrodes with Ultra Low Loading M. Mougenot1, 2

  13. 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.

  14. 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.

  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?¹ Pt, as compared to that of commercially available Pt nanoparticles (0.107 mA ?g?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 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

    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/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.

  17. 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 [Univ. of Pennsylvania, Philadelphia, PA (United States); Su, Dong [Brookhaven National Lab. (BNL), Upton, NY (United States); Doan-Nguyen, Vicky V. T. [Univ. of Pennsylvania, Philadelphia, PA (United States); Wu, Yaoting [Univ. of Pennsylvania, Philadelphia, PA (United States); Li, Jing [Brookhaven National Lab. (BNL), Upton, NY (United States); Sun, Shouheng [Brown Univ., Providence, RI (United States); Murray, Christopher B. [Univ. of Pennsylvania, Philadelphia, PA (United States); Hao, Yizhou [Univ. of Pennsylvania, Philadelphia, PA (United States)

    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/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; 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.

  19. 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

  20. 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.

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

    SciTech Connect (OSTI)

    Lei, Y.; 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, J. 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. Highresolution scanning transmission electron microscopy images showed monodispersed Pt?Pd nanoparticles on ALD Al2O3 - and TiO2 -modi?ed 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 con?guration for the Pt? Pd alloys in an H2 environment has a Pt-core, Pd-shell nanostructure. 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.

  2. 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

  3. 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%.

  4. 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.

  5. Correlating Extent of Pt–Ni 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.

  6. 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.

  7. 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 Fe?.?(Pd{sub 1–x}Pt{sub x})?.? alloy films was studied by time-resolved magneto-optical Kerr effect and ferromagnetic resonance. The intrinsic Gilbert damping parameter ?? 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.

  8. Microstructural Characterization and Shape Memory Response of Ni-Rich NiTiHf and NiTiZr High Temperature Shape Memory Alloys 

    E-Print Network [OSTI]

    Evirgen, Alper

    2014-08-14

    NiTiHf and NiTiZr high temperature shape memory alloys (HTSMAs) have drawn a great deal of attention as cheaper alternatives to Pt, Pd and Au alloyed NiTi-based HTSMAs while NiTiZr alloys also providing at least 20% weight reduction then its Ni...

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

    SciTech Connect (OSTI)

    Kojima, S. [JGC Corporation (Japan); Yokosawa, M. [JGC Corporation (Japan); Matsuyama, M. [Toyama University (Japan); Numata, M. [JGC Corporation (Japan); Kato, T. [JGC Corporation (Japan); Watanabe, K. [Toyama University (Japan)

    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.

  10. 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.

  11. 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.}

  12. Frequency Dependence Modulus of Pd??Ni??Cu??P?? Amorphous Alloy around the Glass Transition by Dynamic Mechanical Analysis

    E-Print Network [OSTI]

    Lee, M.L.

    Dynamic Mechanical Analyzer (DMA) was used to study the frequency dependence of storage and loss modulus of amorphous Pd??Ni??Cu??P?? alloy over a broad frequency range around its glass transition temperature. The amorphous ...

  13. 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.

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

    SciTech Connect (OSTI)

    Karao?lu, E.; Özel, U.; Caner, C.; Baykal, A.; Summak, M.M.; Sözeri, 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, UV–Vis 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 99–93% and 98–93%, 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.

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

    SciTech Connect (OSTI)

    Tsai, An-Pang [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); National Institute for Materials Science, Tsukuba 305-0047 (Japan); Kimura, Tomofumi; Suzuki, Yukinori; Kameoka, Satoshi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Shimoda, Masahiko [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Ishii, Yasushi [Department of Physics, Chuo University, Kasuga, Tokyo 112-8551 (Japan)

    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.

  16. 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 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 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 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.

  17. 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

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

    SciTech Connect (OSTI)

    Zhang, Ying [Tennessee Technological University; Stacy, J P [Tennessee Technological University; Pint, Bruce A [ORNL; Haynes, James A [ORNL; Hazel, Brian T [GE Aviation; Nagaraj, Ben [GE Aviation

    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.

  19. 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.

  20. 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 250–400?°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 10–20 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.

  1. 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.

  2. 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.

  3. 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 O–H bond cleavage, followed by C–H and the second O–H bond cleavages, whereas on the Ni/Pt surface, both O–H 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.

  4. Well-defined ultrathin Pd films on Pt(111): electrochemical preparation and interfacial chemistry 

    E-Print Network [OSTI]

    Park, Yeon Su

    2005-08-29

    voltammetric techniques in combination with low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES). The voltammetric peaks associated with H-atom adsorption and desorption on terrace sites indicate that the Pd electrodeposit starts...

  5. Digital Deposition of Ultrathin Pd Films on Well-Defined Pt(111) Electrodes via Surface-Limited Redox Replacement Reaction: An Electron Spectroscopy-Electrochemistry Study 

    E-Print Network [OSTI]

    Hossain, Mohammad

    2010-12-04

    metal films on well-defined surfaces .......................... 2 1.2 Pd films on platinum ............................................................................ 6 1.3 Electrodeposition of ultrathin films... studied the effect of the modification of low index Pt single crystals by controlled amounts of electrodeposited Ru on methanol oxidation. It has been reported that Pt(111) surfaces covered by 0.2 monolayer of Ru showed an order magnitude higher...

  6. 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 lower temperatures ({approx}970 C) in the very early stage of oxidation. It was also inferred that Pt enhances the diffusive flux of aluminum from the substrate to the scale/alloy interface. Relatively low levels of hafnium addition to Pt-free {gamma}{prime}-Ni{sub 3}Al increased the extent of external NiO formation due to non-protective HfO{sub 2} formation. Accordingly, this effect intensified with increasing Hf content from 0.2 to 0.5 at.%.

  7. 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.

  8. Middle distillate hydrotreatment zeolite catalysts containing Pt/Pd or Ni 

    E-Print Network [OSTI]

    Marin-Rosas, Celia

    2009-05-15

    dibenzothiophenes (sDBT) and phenanthrene as well as molar-averaged conversion was evaluated in a continuous flow Robinson Mahoney reactor with stationary basket in the hydrodesulfurization and hydrogenation of heavy gas oil which contains sulphur refractory...

  9. Shape memory behavior of ultrafine grained NiTi and TiNiPd shape memory alloys 

    E-Print Network [OSTI]

    Kockar, Benat

    2009-05-15

    The cyclic instability in shape memory characteristics of NiTi-based shape memory alloys (SMAs), such as transformation temperatures, transformation and irrecoverable strains and transformation hysteresis upon thermal and ...

  10. 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.

  11. Effect of modifier Pd metal on hydrocracking of polyaromatic compounds over Ni-loaded Y-type zeolite and its application as hydrocracking of polyaromatic compounds over Ni-loaded Y-type zeolite and its application as hydrodesulfurization catalysts

    SciTech Connect (OSTI)

    Wada, T.; Murata, S.; Nomura, M. [Osaka Univ. (Japan)

    1995-12-31

    We have been studying the hydrocracking of polyaromatic compounds over Ni-loaded zeolite catalysts (ZSM-5, mordenite, and Y-type) and found the fact that pore size of zeolite exerts an interesting effect on product distribution. In this study, we have conducted the hydrocracking of pyrene using Pd-modified Ni-loaded Y-type zeolite as catalyst. Addition of Pd-metal activated Ni-loaded Y-type zeolite at a great extent. 100% conversion of pyrene was attained under milder conditions like at 325{degrees}C for 1 h (H{sub 2} 70 kg/cm{sup 2}) while Ni-loaded Y-type zeolite can attain 100% conversion at 350{degrees}C for 1 h. Detailed analysis of product distribution suggested us to apply this catalyst for the hydrodesulfurization of dibenzothiophene. We have conducted hydrocracking of dibenzothiophene at 300{degrees}C for 1 h and found that almost all of dibenzothiophene was hydrocracked while both Ni-loaded Y-type zeolite and Pd-loaded Y-type zeolite show about 10-15% of starting materials remained. This result clearly indicates that modifier Pd-metal shows a kind of synergy for hydrodesulfurization of dibenzothiophene.

  12. 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.}

  13. 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.

  14. Modulating the reactivity of Ni-containing Pt,,111...-skin catalysts by density functional theory calculations

    E-Print Network [OSTI]

    Li, Weixue

    the reaction rates. Since hy- drogen fuel normally comes from reforming process, the presence of a few catalytic activity with better CO tolerance and decreasing amount of Pt, or even replacement of Pt of adsorbates. CO poison can, however, be partially relieved by remov- ing CO from reforming process via

  15. Systematics of the temperature-dependent interplane resistivity in Ba(Fe1-xMx)?As? (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 ?c(T) was measured systematically as a function of transition-metal substitution in the iron-arsenide superconductors Ba(Fe1-xMx)?As?, M=Ni, Pd, Rh. The data are compared with the behavior found in Ba(Fe1-xCox)?As?, 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 ?c 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

  16. 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

  17. 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 - Université 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.

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

    E-Print Network [OSTI]

    Horwat, D.

    2009-01-01

    2009) Deep oxidation of methane on particles derived fromAbstract Methane conversion tests were performed on Pd, PdOFigure captions Figure 1: Methane conversion a), methane

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

    E-Print Network [OSTI]

    Horwat, D.

    2009-01-01

    deposited on yttria stabilized zirconia (YSZ) substrates. Ptstudy, yttria stabilized zirconia (YSZ) supported Pd-basedat the surface of the zirconia substrate (Fig. 4). PdO y

  20. Following Molecules through Reactive Networks: Surface Catalyzed Decomposition of Methanol on Pd(111), Pt(111), and Ni(111)

    E-Print Network [OSTI]

    Li, Weixue

    , United States State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Dalian 116023

  1. Effect of modifier Pd metal on hydrocracking of polyaromatic compounds over Ni-loaded Y-type zeolite and its application as hydrodesulfurization catalysts

    SciTech Connect (OSTI)

    Wada, Takema; Murata, Satoru; Nomura, Masakatsu [Osaka Univ. (Japan)

    1995-12-31

    Coal tar obtained from coal carbonization is a treasure of polyaromatic hydrocarbons, where more than 400 kinds of aromatic compounds are found to be contained. The development of new catalysts being able to convert these aromatics into mono or diaromatic compounds is one of objectives for utilization of polyaromatics. Hydrocracking of polyaromatic compounds is believed to proceed via formation of terminal-naphthenic ring of starting aromatic compounds, followed by cleavage of the naphthenic ring to produce alkylated aromatic compounds which has less numbers of ring than starting aromatics. Accordingly, hydrogenation of aromatic rings and cracking of resulting naphthenic rings are key steps of hydrocracking reaction, so that dual functional catalysts such as metal-supported acid catalysts are considered to be one of the best catalysts. Zeolite has controlled pore structures and strong acidity enough to crack naphthenic rings, being characteristics in exchanging metal species with ease. We have been studying the hydrocracking of polyaromatic compounds over Ni-loaded zeolite catalysts (ZSM-5, mordenite, and Y-type) and found the fact that pore size of zeolite exerts an interesting effect on product distribution. We also conducted computer-simulation for diffusion phenomena of the polyaromatic hydrocarbons in the pore of these zeolites and found that diffusion ability of the substrate affects strongly the product distributions Recently we found that modifying of Ni-loaded Y-type zeolite by Pd-loading enhanced hydrocracking ability of the catalyst. In this report, we would like to refer to the results of both hydrocracking reaction of pyrene and hydrodesulfurization of dibenzothiophene using Pd-modified Ni-loaded Y-type zeolite.

  2. Chemisorption of atomic oxygen on Pt(1 1 1) and Pt/Ni(1 1 1) surfaces Timo Jacob, Boris V. Merinov, William A. Goddard III *

    E-Print Network [OSTI]

    Goddard III, William A.

    at electrodes provides a significant opportunity for im- proving fuel cell performance. To make progress. Nowadays in PEM fuel cells Pt and Pt-based mate- rials are commonly used to catalyze the reactions Elsevier B.V. All rights reserved. 1. Introduction Optimization of the electro-catalytic processes

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

    E-Print Network [OSTI]

    Horwat, D.

    2009-01-01

    and stabilize the catalytic oxidation of methane via Pd-Ptthe only oxidation product detected. The catalytic rate was

  4. 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.

  5. 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.

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

    DOE Patents [OSTI]

    Benn, Raymond C. (Madison, CT); Opalka, Susanne M. (Glastonbury, CT); Vanderspurt, Thomas Henry (Glastonbury, CT)

    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.

  7. The synthesis and structural properties of [M(dippe)(g2 complexes of Pd and Pt and comparison with their Ni analog

    E-Print Network [OSTI]

    Jones, William D.

    ) is the process used to remove sulfur from petroleum feedstocks. The most com- monly used catalyst is Co to promote the activation and desulfurization of substituted thiophenes [5­8]. To study the effect of the d8

  8. 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 inconsistent proportions of metal and glassy phase particles present during the subsequent firing process. The consequences were subtle, intermittent changes to the thick film microstructure that gave rise to the reaction layer and, thus, the low pull strength phenomenon. A mitigation strategy would be the use of physical vapor deposition (PVD) techniques to create thin film bond pads; this is multi-chip module, deposited (MCM-D) technology.

  9. Effect of Spin-Crossover-Induced Pore Contraction on CO{sub 2}-Host Interactions in the Porous Coordination Polymers [Fe(pyrazine)M(CN){sub 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){sub 4}] and [Fe(pyrazine)Pt(CN){sub 4}] under CO{sub 2} pressures of up to 8 bar. Significant shifts in the ?{sub 3} and ?{sub 2} IR absorption bands of adsorbed CO{sub 2} are observed as the host materials undergo transition between low- and high-spin states. Computational models used to determine the packing arrangement of CO{sub 2} within the pore structures show a preferred orientation of one of the adsorbed CO{sub 2} 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 CO{sub 2} molecule, which allows the adsorbed CO{sub 2} 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 CO{sub 2} 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 CO{sub 2}–host interactions.

  10. 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.

  11. The combustion synthesis of Ni-Ti shape memory alloys

    SciTech Connect (OSTI)

    Moore, J.J.; Yi, H.C. (Colorado School of Mines, Golden (USA))

    1990-08-01

    Combustion synthesis of Ni-Ti-series shape-memory alloys yields both time and energy savings over conventional production methods. The solidified combustion synthesis process products have been cold-rolled into plates which exhibit the shape-memory effect, and it was noted that shape-memory transition temperatures may be tailored over a -78 to 460 C temperature range through the substitution of a third element for Ni; this element may be Pd or Fe. Accounts are given of the experimental combustion syntheses of Ni-Ti-Fe and Ti-Ni-Pd. 24 refs.

  12. Self-assembled nano- to micron-size fibers from molten R11Ni4In9 intermetallics

    SciTech Connect (OSTI)

    Provino, Alessia; Manfrinetti, Pietro; Gschneidner, Karl A.; Dhar, Sudesh K.; Schlagel, Deborah L.; Lograsso, Thomas A.; Miller, Gordon J.; Thimmaiah, Srinivasa; Wang, Hui; Russell, Alan M.; Becker, Andrew; Mudryk, Yaroslav

    2014-07-01

    A study of the formation of Gd11M4In9 (M = Ni, Pd, Pt) and R11Ni4In9 (R = rare earth) compounds revealed a unique and peculiar property, which is to naturally crystallize in a bundle of self-assembled fibers when cooled from the melt. The fibers, which are nano- to millimeters in cross-section and approximate to 11-40 mm long, grow unidirectionally along a temperature gradient. These compounds adopt the orthorhombic Nd11Pd4In9 structure type (oC48-Cmmm). This structure is layered, with slabs of R atoms alternating with slabs of Ni/In atoms along a short c-axis (much shorter than either the a- or b-axis). The growth direction of the fibers is along the crystallographic c-axis, orthogonal to the a-b plane. Two strong and short In In bonds lie in the a-b plane, which are even shorter than in In metal. Integrated crystal orbital Hamilton population calculations show that the In In bonds create isolated "R8Ni4In9" rods growing along the c-axis, with the In In bonds being part of the rods. This appears to be an important factor explaining the microfibrous nature of these phases. Some physical properties have been measured on the Gd11Ni4In9 homolog. The compound orders ferrimagnetically at T-c approximate to 88 K, and at lower temperatures (46 and 10 K), two other magnetic anomalies were observed, probably due to spin reorientations. As expected from the bonding features, the mechanical, magnetic and electrical properties are strongly anisotropic. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  13. Fuel cell with Pt/Pd electrocatalyst electrode

    DOE Patents [OSTI]

    Stonehart, Paul (Madison, CT)

    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.

  14. 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 [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Jagirdar, Balaji R., E-mail: jagirdar@ipc.iisc.ernet.i [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India)

    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.

  15. Electrodeposition of ultrathin Pd, Co and Bi films on well-defined noble-metal electrodes: studies by ultrahigh vacuum-electrochemistry (UHV-EC) 

    E-Print Network [OSTI]

    Baricuatro, Jack Hess L

    2006-10-30

    Three illustrative cases involving the electrodeposition of ultrathin metal films of varying reactivities onto noble-metal substrates were investigated: (i) Pd on Pt(111), a noble admetal on a noble-metal surface; (ii) Bi ...

  16. Oxygen Reduction Activity of PtxNi1-x Alloy Nanoparticles on Multiwall Carbon Nanotubes

    E-Print Network [OSTI]

    Kim, Junhyung

    PtxNi1 - x nanoparticles (Pt:Ni; 1:0, 4:1, 3:1 and 0.7:1) of ~5 nm, were synthesized on carboxylic acid-functionalized multiwall carbon nanotubes (PtxNi1 - x NPs/MWNT). The oxygen reduction reaction (ORR) activity measurements ...

  17. 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.

  18. PT-symmetric strings

    SciTech Connect (OSTI)

    Amore, Paolo; Fernández, 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.

  19. 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.

  20. 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..

  1. 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.

  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. 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. [Department of Chemistry, Moscow State University, 119992, Moscow (Russian Federation)], E-mail: panin@icr.chem.msu.ru; Khasanova, Nellie R. [Department of Chemistry, Moscow State University, 119992, Moscow (Russian Federation); Abakumov, Artem M. [Department of Chemistry, Moscow State University, 119992, Moscow (Russian Federation); Antipov, Evgeny V. [Department of Chemistry, Moscow State University, 119992, Moscow (Russian Federation); Tendeloo, Gustaaf van [EMAT University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Schnelle, Walter [Max-Planck Institute for Chemical Physics of Solids, Noethnitzer Street 40, 01187 Dresden (Germany)

    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.

  4. 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; Changchun Univ., Changchun; 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

  5. 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

  6. 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

  7. Martensitic transformation in Pd-rich FePdPt alloy Taishi Wada, Tetsuya Tagawa, Minoru Taya *

    E-Print Network [OSTI]

    Taya, Minoru

    , 2, 4, 6 and 8 at.%. Weighted iron granular (99.98%), palladium powder (99.95%) and plati- num powder

  8. Introduction: Bencubbin-like meteorites (CB) are metal-rich chondritic breccias containing about 60 vol% metallic (Fe,Ni) [1]. Unlike the CBa (Becubbin, Weatherford,

    E-Print Network [OSTI]

    vol% metallic (Fe,Ni) [1]. Unlike the CBa (Becubbin, Weatherford, Gujba) subgroup, the CBb (HH 237 al. [4] found that the Ir/Fe, Pd/Fe and Ni/Fe ratios in unzoned metal grains in the CBa chondrites that the components of CBa and CBb chondrites formed in a giant impact: SO chondrules and unzoned metal in Gujba

  9. Synthesis and Oxidation Behavior of Platinum-Enriched ?+?' Bond Coatings on Ni-Based Superalloys

    SciTech Connect (OSTI)

    Zhang, Ying [Tennessee Technological University; Ballard, D A [Tennessee Technological University; Stacy, J P [Tennessee Technological University; Pint, Bruce A [ORNL; Haynes, James A [ORNL

    2006-01-01

    Simple Pt-enriched {gamma}+{gamma}{prime} coatings were synthesized on Rene 142 and Rene N5 Ni-based superalloys by electroplating a thin layer of Pt followed by a diffusion treatment at 1150-1175 C. The Al content in the resulting {gamma}+{gamma}{prime} coating was in the range of 16-19 at.% on superalloys with 13-14 at.% Al. After oxidation testing, alumina scale adherence to these {gamma}+{gamma}{prime} coatings was not as uniform as to the {beta}-(Ni,Pt)Al coatings on the same superalloy substrates. To better understand the effect of Al, Pt and Hf concentrations on coating oxidation resistance, a number of Ni-Pt-Al cast alloys with {gamma}+{gamma}{prime} or {beta} phase were cyclically oxidized at 1100 C. The Hf-containing {gamma}+{gamma}{prime} alloys with 22 at.% Al and 10-30 at.% Pt exhibited similar oxidation resistance to the {beta} alloys with 50 at.% Al. An initial effort was made to increase the Al content in the Pt-enriched {gamma}+{gamma}{prime} coatings by introducing a short-term aluminizing process via chemical vapor deposition or pack cementation. However, too much Al was deposited, leading to the formation of {beta} or martensitic phase on the coating surface.

  10. 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. [Institut fuer Anorganische Chemie, Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany); Matar, S.F., E-mail: matar@icmcb-bordeaux.cnrs.f [CNRS, University of Bordeaux, ICMCB, 87 avenue du Docteur A. Schweitzer, F-33600 Pessac (France); Anusca, I.; Pielnhofer, F.; Peter, P.; Bachhuber, F. [Institut fuer Anorganische Chemie, Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany); Eyert, V. [Center for Electronic Correlations and Magnetism, Institute for Physics, University of Augsburg, D-86135 Augsburg (Germany)

    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.

  11. Influence of stoichiometry and growth temperature on the crystal structure and magnetic properties of epitaxial L1{sub 0} Fe-Pd (001) films

    SciTech Connect (OSTI)

    Chang, Y. C. [Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan (China); Hsiao, S. N., E-mail: pmami.hsiao@gmail.com; Liu, Y. T.; Lee, H. Y., E-mail: hylee@nsrrc.org.tw [National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan (China); Liu, S. H.; Chen, S. K. [Department of Material Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China); Sun, A. C. [Department of Chemical Engineering and Material Science, YunZe University, Chungli 135, Taiwan (China); Dhu, J. G., E-mail: jgdhu@nthu.edu.tw [Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China)

    2014-05-07

    To investigate the crystallographic structure and the magnetic properties as a function of chemical composition (40–62 at. %) and substrate temperature (T{sub s}?=?300–550?°C), we fabricated epitaxial FePd films of thickness 20?±?2?nm by sputtering on MgO (100) single-crystal substrates. The ordering parameter, measured by x-ray diffraction with synchrotron radiation, and the perpendicular anisotropy of the Fe{sub 54}Pt{sub 46} films increased with increasing substrate temperature. For FePd films (T{sub s}?=?550?°C) with varied Fe content, a direct correlation between the ordering parameter and the magnetocrystalline anisotropy field is found. The greatest ordering parameter, 0.84, and magnetocrystalline anisotropy field, ?20 kOe, were obtained for FePd films of Fe concentration 54 at. %, indicating that an off-stoichiometric L1{sub 0} FePd might be preferable for engineering and applications.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Ni Ni: University of California - Los Angeles

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shinesSolarNew scholarshipThreeFebruary 2015 ESH&SCSU - EnergyNi Ni:

  18. 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}

  19. Path Integral Solution of PT-/non-PT-Symmetric and non-Hermitian Morse Potential

    E-Print Network [OSTI]

    Nalan Kandirmaz; Ramazan Sever

    2008-12-14

    Path integral solutions are obtained for the the PT-/non-PT-Symmetric and non-Hermitian Morse Potential. Energy eigenvalues and the corresponding wave functions are obtained.

  20. Grain size dependence of fracture toughness and crack-growth resistance of superelastic NiTi

    E-Print Network [OSTI]

    Sun, Qing-Ping

    Available online xxxx Keywords: Shape memory alloys Martensitic phase transformation Microstructure to a reversible martensitic phase transformation (PT), superelastic (SE) NiTi shape memory alloys (SMAs with thickness of 1.7 mm were sandwiched in stainless steel sheets and were cold-rolled to 42% of thickness

  1. 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}(PMN–PT, ?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 PMN–PT film was in situ acquired at zero magnetic field. The obtained Kerr signal versus voltage loop essentially tracks the electromechanical strain curve of the PMN–PT thin film, clearly demonstrating a strain-mediated converse magnetoelectric coupling, i.e., voltage-modulated magnetization, in the NiFe/PMN–PT nanocomposite thin films.

  2. 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.

  3. 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)

  4. Cincia Hoje.pt Pas: Portugal

    E-Print Network [OSTI]

    Instituto de Sistemas e Robotica

    Tweet http://www.fccn.pt http://twitter.com/CienciaHojept http://www.facebook.com/pages/Ciencia- HojeCiência Hoje.pt País: Portugal Period.: Diária Âmbito: Online Pag.: 1 de 3ID: 44173380 10 Contactos #12;Ciência Hoje.pt País: Portugal Period.: Diária Âmbito: Online Pag.: 2 de 3ID: 44173380 10

  5. UNCW PD FORM 403 APPROVED 06/01/2010

    E-Print Network [OSTI]

    Olszewski Jr., Edward A.

    UNCW PD FORM 403 APPROVED 06/01/2010 UNIVERSITY POLICE DEPARTMENT APPLICATION FOR RIDE ALONG;UNCW PD FORM 403 APPROVED 06/01/2010 Requested Ride Date and Time Signed by me this day of , 20

  6. 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.

  7. Vertically graded anisotropy in Co/Pd multilayers

    E-Print Network [OSTI]

    2010-01-01

    F. Majkrzak et al. , in Neutron Scattering From Magnetic Ma-Pd multilayer ?lms. Neutron-scattering measurements reveal a

  8. 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.

  9. 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}.

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

    SciTech Connect (OSTI)

    Paglieri, Stephen N [Los Alamos National Laboratory; Wermer, Joseph R [Los Alamos National Laboratory; Buxbaum, Robert E [REB RESEARCH AND CONSULTING; Ciocco, Michael V [NETL; Howard, Bret H [NETL; Morreale, Bryan D [NETL

    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.

  11. Approved Module Information for PD2003, 2014/5 Module Title/Name: Engineering Principles 2 Module Code: PD2003

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for PD2003, 2014/5 Module Title/Name: Engineering Principles 2 Module Code: PD2003 School: Engineering and Applied Science Module Type: Standard Module New Module? No Module? No Module Dependancies Pre-requisites: Engineering Principles (PD1803). Co-requisites: None Specified Module

  12. 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.

  13. 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.

  14. Evidence for large hydrogen storage capacity in single-walled carbon nanotubes encapsulated by electroplating Pd onto a Pd substrate

    SciTech Connect (OSTI)

    Lipson, A. G. [Department of Nuclear Plasma and Radiological Engineering, University of Illinois, Urbana, Illinois 61801 (United States); A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119991, Moscow (Russian Federation); Lyakhov, B. F.; Saunin, E. I.; Tsivadze, A. Yu. [A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119991, Moscow (Russian Federation)

    2008-02-15

    We report a study of hydrogen storage in an alternative material, representing single-walled carbon nanotubes (SWCNTs) encapsulated by thin Pd layers onto a Pd substrate. A synergetic effect resulting in combination of the Pd and the SWCNTs properties with regards to hydrogen has been achieved. Adding SWCNTs increases the H{sub 2} capacity of the Pd-SWCNT composite by up to 25% relative to Pd metal alone under electrochemical loading. This results in a storage capacity of 8-12 wt %. with regard to the added SWCNTs.

  15. 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

  16. A Platinum-Enriched gamma+gamma' Two-Phase Bond Coat on Ni-Base Superalloys

    SciTech Connect (OSTI)

    Zhang, Ying [Tennessee Technological University; Pint, Bruce A [ORNL; Haynes, James A [ORNL; Wright, Ian G [ORNL

    2005-01-01

    Pt-enriched {gamma} + {gamma}{prime} two-phase coating was applied to directionally-solidified Ni-based superalloy Ren{acute e} 142 substrates with three different Hf levels (0.02, 0.76, and 1.37 wt.%). The coating was prepared by electroplating a thin layer of Pt on the superalloy followed by a diffusion treatment. The as-deposited coating exhibited a {gamma} + {gamma}{prime} two-phase microstructure with a major composition of Ni-16Al-18Pt-7Cr-9Co (in at.%) along with some incorporation of refractory elements from the substrates. Cyclic oxidation testing at 1100 C in air indicated improved oxidation resistance of the Ren{acute e} 142 alloys with the Pt-enriched {gamma} + {gamma}{prime} coatings. In addition, the oxidation resistance of both uncoated and coated alloys was proportional to the Hf content in the substrate. Compared with the single-phase {beta}-(Ni,Pt)Al coating, slightly higher mass gains and localized spallation were observed on the {gamma} + {gamma}{prime} two-phase coating, which might be due to the segregation of refractory elements and high sulfur levels in these superalloy substrates.

  17. Encapsulation of Pt(IV) prodrugs within a Pt(II) cage for drug delivery

    E-Print Network [OSTI]

    Suntharalingam, Kogularamanan

    This report presents a novel strategy that facilitates delivery of multiple, specific payloads of Pt(IV) prodrugs using a well-defined supramolecular system. This delivery system comprises a hexanuclear Pt(II) cage that ...

  18. 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.

  19. TRAC-PD2 analysis of FLECHT experiments. [PWR

    SciTech Connect (OSTI)

    Bott, T.F.; Mandell, D.A.

    1981-01-01

    This report describes TRAC-PD2 calculations of FLECHT (Full Length Emergency Cooling Heat Transfer) tests 4831 and 17201. The calculations were performed as part of the TRAC-PD2 developmental assessment where the objective was to assess TRAC-PD2 reflood modeling under forced flooding conditions. Calculated and experimental values for peak fuel-rod clad temperature, clad quenching time, and rod bundle effluent rates are compared; and calculations with an approximate radiation heat-transfer model added to the basic TRAC-PD2 code are performed. Findings demonstrate the potential importance of surface-to-surface radiation heat transfer in these tests.

  20. Vertically graded anisotropy in Co/Pd multilayers

    E-Print Network [OSTI]

    2010-01-01

    substrate with a native oxide layer and were capped with a 5Pd seed layer, native oxide layer, and the Si substrate at

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

    Office of Scientific and Technical Information (OSTI)

    Chemical and Morphological Evolution of Nanoporous PdRh Alloy Particles for Hydrogen Storage. Citation Details In-Document Search Title: Chemical and Morphological Evolution of...

  2. Thermomechanical Cyclic Response of TiNiPd High-Temperature Shape Memory Alloys 

    E-Print Network [OSTI]

    Atli, Kadri

    2012-10-19

    inhibiting the generation of these defects. Solid-solution strengthening through Sc microalloying and thermomechanical treatments via severe plastic deformation were the two approaches used to strengthen the HTSMA against defect generation. Thermal cycling...

  3. Scanning tuneeling microscopy studies of fivefold surfaces of icosahedral Al-Pd-Mn quasicrystals and of thin silver films on those surfaces

    SciTech Connect (OSTI)

    Unal, Baris

    2008-12-01

    The present work in this dissertation mainly focuses on the clean fivefold surfaces of i-Al-Pd-Mn quasicrystals as well as the nucleation and growth of Ag films on these surfaces. In addition, Ag film growth on NiAl(110) has been explored in the frame of this dissertation. First, we have investigated the equilibration of a fivefold surface of icosahedral Al-Pd-Mn quasicrystal at 900-915 K and 925-950 K, using Omicron variable temperature scanning tunneling microscope (STM). Annealing at low temperatures resulted in many voids on some terraces while the others were almost void-free. After annealing at 925-950K, void-rich terraces became much rarer. Our STM images suggest that through growth and coalescence of the voids, a different termination becomes exposed on host terraces. All of these observations in our study indicate that even after the quasicrystalline terrace-step structure appears, it evolves with time and temperature. More specifically, based on the STM observations, we conclude that during the annealing a wide range of energetically similar layers nucleate as surface terminations, however, with increasing temperature (and time) this distribution gets narrower via elimination of the metastable void-rich terraces. Next, we have examined the bulk structural models of icosahedral Al-Pd-Mn quasicrystal in terms of the densities, compositions and interplanar spacings for the fivefold planes that might represent physical surface terminations. In our analyses, we mainly have focused on four deterministic models which have no partial or mixed occupancy but we have made some comparisons with an undeterministic model. We have compared the models with each other and also with the available experimental data including STM, LEED-IV, XPD and LEIS. In all deterministic models, there are two different families of layers (a pair of planes), and the nondeterministic model contains similar group of planes. These two families differ in terms of the chemical decoration of their top planes. Hence, we name them as Pd+(with Pd) and Pd-(without Pd). Based on their planer structure and the step height, it can be said that these two families can be viable surface terminations. However, besides the Pd content, these two sets differ in terms of relative densities of their top planes as well as the gap separating the layer from the nearest atomic plane. The experimental data and other arguments lead to the conclusion that the Pd- family is favored over the Pd+. This has an important implication on the interpretation of local motifs seen in the high resolution STM images. In other words, the dark stars are not formed by cut-Bergmans rather they are formed by cut-Mackays.

  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. 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...

  7. 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 ? 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.

  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. 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. [Institut de Chimie de la Matiere Condensee de Bordeaux (ICMCB) - CNRS, Universite de Bordeaux 1, 87 Avenue du Dr A. Schweitzer, F-33608 PESSAC (France); Veeco, Z.I. de la Gaudree, 11 Rue Marie Poussepin, F-91412 Dourdain (France)

    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.

  10. Thermoelectric effect in very thin film Pt/Au thermocouples

    E-Print Network [OSTI]

    Salvadori, M.C.; Vaz, A.R.; Teixeira, F.S.; Cattani, M.; Brown, I.G.

    2006-01-01

    TABLE I. Measured thermoelectric power S for samples ofThermoelectric effect in very thin film Pt/Au thermocouplesthickness dependence of the thermoelectric power of Pt films

  11. Electrochemical hydrogenation of aromatic compounds chemisorbed at polycrystalline and single-crystal Pd surfaces 

    E-Print Network [OSTI]

    Sanabria-Chinchilla, Jean

    2009-06-02

    The chemisorption and electrochemical hydrogenation of hydroquinone (H2Q) at polycrystalline (pc) Pd, well-ordered Pd(100), and Pd-modified Au(hkl) electrodes were studied using a combination of ultra-high vacuum (UHV) surface spectroscopy...

  12. This journal is c the Owner Societies 2013 Phys. Chem. Chem. Phys. Cite this: DOI: 10.1039/c3cp50793a

    E-Print Network [OSTI]

    properties, leading to tailored selectivity and enhanced chemical reactivity. In particular, the catalysis reforming reactions, including Au/Ni8 and Pt/Ni9 for methane steam reforming, and Zn/Pd which of Pd(111) surfaces with low (o0.5 ML) coverages of Zn. Based on LEED, Jeroro et al. propose that a p(2

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

    DOE Patents [OSTI]

    Eichhorn, Bryan W. (University Park, MD); Zhou, Shenghu (Greenbelt, MD); Jackson, Gregory Scott (University Park, MD)

    2011-10-18

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

  14. Pd-Catalyzed Wacker Cyclizations Palladium-Catalyzed Oxidative Wacker

    E-Print Network [OSTI]

    Stoltz, Brian M.

    Pd-Catalyzed Wacker Cyclizations Palladium-Catalyzed Oxidative Wacker Cyclizations in Nonpolar stoichiometric oxidant. Palladium-catalyzed bond-forming constructions have become indispensable in organic chemistry.[4] A favorable property of palladium is that it can serve as both a nucleophile (i.e., Pd0

  15. Approved Module Information for PD1803, 2014/5 Module Title/Name: Engineering Principles Module Code: PD1803

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for PD1803, 2014/5 Module Title/Name: Engineering Principles Module Code: PD1803 School: Engineering and Applied Science Module Type: Standard Module New Module? No Module; * have a knowledge and understanding of and be able to apply the basic engineering principles

  16. Approved Module Information for PD2002, 2014/5 Module Title/Name: Commercial Practice Module Code: PD2002

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for PD2002, 2014/5 Module Title/Name: Commercial Practice Module Code: PD2002 School: Engineering and Applied Science Module Type: Standard Module New Module? No Module Credits: 20 Module Management Information Module Leader Name Jon Hewitt Email Address Not Specified

  17. Pd conductor for thick film hydrogen sensor

    SciTech Connect (OSTI)

    Felten, J.J. [DuPont Electronics, Research Triangle Park, NC (United States); Hoffheins, B.S.; Lauf, R.J. [Oak Ridge National Lab., TN (United States)

    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.

  18. 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 Pmore »the phase transition.« less

  19. CinciaPT.net Pas: Portugal

    E-Print Network [OSTI]

    Instituto de Sistemas e Robotica

    -06-2012 Start-up do Instituto Superior Técnico Taguspark lança call center na nuvem Escrito por CienciaPT 22 hoje. Entre clientes e potenciais interessados são mais de 1000 os interessadas em usar o nosso

  20. Cincia Hoje.pt Pas: Portugal

    E-Print Network [OSTI]

    Instituto de Sistemas e Robotica

    as propriedades eléctricas e magnéticas de materiais e que promete substituir a electrónica actual. Pela amigos gostam. http://www.fccn.pt http://twitter.com/CienciaHojept http://www.facebook

  1. Phosphorus content effect on the magnetoelectric properties of the NiP(Ni)/PZT/NiP(Ni) cylindrical layered composites

    E-Print Network [OSTI]

    Volinsky, Alex A.

    were polarized along the radial direction after electroplating a thin Ni layer on its inside and outside surfaces. The samples were pretreated with supersonic cleaning prior to Ni electroplating composite is shown else- where [13]. The final thickness of the inside and the outside coatings

  2. Stress Evolution Behavior in CoCrPt Alloy Thin Films with varying Pt Concentration

    E-Print Network [OSTI]

    Im, M.-Y.

    2009-01-01

    Stress Evolution Behavior in CoCrPt Alloy Thin Films withmagnetic recording media is to investigate growth stress,since stress inevitably generated during thin film

  3. Location of platinum clusters in PtCaY and PtNaY zeolites 

    E-Print Network [OSTI]

    Treybig, Duane Steven

    1980-01-01

    ) 350'C . . . ~ . . . . . . . . . . . . . 32 Pt 4f spectra of PtCaY: (A) after heating in flowing oxygen at 100'C for 2 hr, (B) after reduction in flowing hydrogen in increments of 100'C/hr to 350'C, (C) after deammination and dehydration in flowing... oxygen in incre- ments of 100'C/hr to 350'C, evacuation at 25'C followed by reduction in flowing hydrogen in increments oi 100'C/hr to 400'C Pt 4d spectra of PtCaY: (A) after heating in flowing oxygen at 100'C for 2 hr, (B) after reduction...

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

    DOE Patents [OSTI]

    Marks, Tobin J. (Evanston, IL); Rodriguez, Brandon A. (Evanston, IL); Delferro, Massimiliano (Chicago, IL)

    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.

  5. 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.

  6. Catalytic studies of supported Pd-Au catalysts 

    E-Print Network [OSTI]

    Boopalachandran, Praveenkumar

    2006-08-16

    -Au Bimetallic Supported Catalysts Palladium (Pd) is a well known catalyst for many reactions which are of industrial and environmental importance [7]. A major drawback of using Pd-only catalysts is the formation of carbides, i.e. PdCx, as shown in the Fig. 1... reveal that the addition of gold to palladium catalysts has pronounced catalytic effect [3, 6]. It is plausible that the electronic and geometric properties are tuned by the addition of Au with highly optimized sites [3, 6, 11]. Also, model catalytic...

  7. 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.

  8. ENHANCEMENT OF SUPERCONDUCTING Tc IN Pd-H LIKE COMPOUNDS BY OPTICAL PHONONS

    E-Print Network [OSTI]

    Boyer, Edmond

    1227 ENHANCEMENT OF SUPERCONDUCTING Tc IN Pd-H LIKE COMPOUNDS BY OPTICAL PHONONS J. P. BURGER and D.450 1. Introduction. - The high superconducting tran- sition temperatures recently observed in Pd [1 interaction inhibiting superconductivity in pure Pd. As the density of states in Pd-H is rather similar [5

  9. 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.

  10. Investigation of Pt, Pt3Co, and Pt3CoMo Cathodes for the ORR in a Microfluidic H2O2 Fuel Cell

    E-Print Network [OSTI]

    Kenis, Paul J. A.

    Investigation of Pt, Pt3Co, and Pt3CoÕMo Cathodes for the ORR in a Microfluidic H2ÕO2 Fuel Cell on the performance and durability of four Pt-based cathode catalysts in a microfluidic H2/O2 fuel cell: commercial performed using an acidic microfluidic H2/O2 fuel cell with an analytical platform. The electrolyte flow

  11. Dialkylbiaryl phosphines in Pd-catalyzed amination: a user's guide

    E-Print Network [OSTI]

    Surry, David S.

    Dialkylbiaryl phosphines are a valuable class of ligand for Pd-catalyzed amination reactions and have been applied in a range of contexts. This perspective attempts to aid the reader in the selection of the best choice of ...

  12. The Role of the PD-1 Immunoreceptor in Pregnancy

    E-Print Network [OSTI]

    Taglauer, Elizabeth Susan

    2008-08-08

    During pregnancy, the maternal immune system must be carefully modulated as the fetus is immunologically foreign to her leukocytes. We propose that the CD28 family immune receptor, PD-1, functions during pregnancy to control ...

  13. 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.

  14. 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.

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

    SciTech Connect (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.

  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 motifmore »is 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. AcqGuide39pt1.doc

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematics AndBerylliumDepartment of Energy8pt1.doc&#0; AcqGuide38pt1.doc&#0; PDF icon

  19. AcqGuide3pt1.doc

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematics AndBerylliumDepartment of Energy8pt1.doc&#0; AcqGuide38pt1.doc&#0; PDF icon

  20. Rationalization of Au concentration and distribution in AuNi@Pt core-shell

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTech ConnectSpeedingConnect PulseSummary (Programbatteries as(Journal

  1. 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.

  2. Jet energy scale setting with "photon+Jet" events at LHC energies. Selection of events with a clean "photon+Jet" topology and photon Pt - jet Pt disbalance

    E-Print Network [OSTI]

    D. V. Bandourin; V. F. Konoplyanikov; N. B. Skachkov

    2001-04-27

    It is shown in the paper that Pt activity limitation (modulus of the vector sum) of all particle beyond "photon+Jet" system Pt^out leads to the noticeable photon Pt - jet Pt disbalance decreasing. On a simultaneous restriction of the cluster Pt and Pt^out from above it is possible to reach an acceptable balance between photon Pt - jet Pt with a sufficient number of the photon Pt - jet Pt events for the jet energy scale setting and hadron calorimeter calibratiom of the CMS detector at LHC.

  3. Influence of nuclear structure on sub-barrier hindrance in Ni+Ni fusion

    E-Print Network [OSTI]

    C. L. Jiang; K. E. Rehm; R. V. F. Janssens; H. Esbensen; I. Ahmad; B. B. Back; P. Collon; C. N. Davids; J. P. Greene; D. J. Henderson; G. Mukherjee; R. C. Pardo; M. Paul; T. O. Pennington; D. Seweryniak; S. Sinha; Z. Zhou

    2004-02-25

    Fusion-evaporation cross sections for $^{64}$Ni+$^{64}$Ni have been measured down to the 10 nb level. For fusion between two open-shell nuclei, this is the first observation of a maximum in the $S$-factor, which signals a strong sub-barrier hindrance. A comparison with the $^{58}$Ni+$^{58}$Ni, $^{58}$Ni+$^{60}$Ni, and $^{58}$Ni+$^{64}$Ni systems indicates a strong dependence of the energy where the hindrance occurs on the stiffness of the interacting nuclei.

  4. Dehydrogenation of Light Alkanes over Supported Pt Catalysts

    E-Print Network [OSTI]

    Wu, Jason

    2015-01-01

    as seen for both ethane and propane dehydrogenation over Pt/was investigated for ethane and propane dehydrogenation.O Chapter 5: Ethane and Propane Dehydrogenation over PtIr/

  5. Cincia Hoje.pt Pas: Portugal

    E-Print Network [OSTI]

    Instituto de Sistemas e Robotica

    Ciência Hoje.pt País: Portugal Period.: Diária Âmbito: Online Pag.: 1 de 4ID: 44151019 09 David Wineland receberam hoje o prémio Nobel da Física 2012 por desenvolverem "métodos experimentais", comenta Carlos Russo ao Ciência Hoje. Segundo o investigador do Instituto de Plasmas e Fusão Nuclear do

  6. 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.

  7. UNCORRECTED Comparison of PdCoAu electrocatalysts prepared by

    E-Print Network [OSTI]

    Ferreira, Paulo J.

    exchange membrane fuel cells (PEMFC). How- ever, the high cost and limited abundance of Pt pose seri- ous for ORR in PEMFC at 60 °C. However, for structure and surface sensitive reactions such as electrocatalysis

  8. 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.

  9. 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.

  10. 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.

  11. Antiproton Production in p+d Reaction at Subthreshold Energies

    E-Print Network [OSTI]

    A. Hasegawa; Y. Iwasaki; K. Sakamoto; N. Noda; H. Kouno; M. Nakano

    1998-03-25

    An enhancement of antiprotons produced in p+d reaction in comparison with ones in p+p elementary reaction is investigated. In the neighborhood of subthreshold energy the enhancement is caused by the difference of available energies for antiproton production. The cross section in p+d reaction, on the other hand, becomes just twice of the one in elementary p+p reaction at the incident energy far from the threshold energy when non-nucleonic components in deuteron target are not considered.

  12. 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 }

  13. Sample & Assay Technologies Ni-NTA Superflow

    E-Print Network [OSTI]

    Lebendiker, Mario

    March 2007 Sample & Assay Technologies Ni-NTA Superflow Cartridge Handbook For manual or FPLCTM purification of His-tagged proteins #12;2 Ni-NTA Superflow Cartridge Handbook 03/2007 Trademarks: QIAGEN, are not to be considered unprotected by law. © 2007 QIAGEN, all rights reserved. #12;Ni-NTA Superflow Cartridge Handbook 03

  14. Direct Determination of the Ionization Energies of PtC, PtO, and PtO2 with VUV Radiation

    E-Print Network [OSTI]

    Citir, Murat

    2008-01-01

    binary-encounter Bethe (BEB) method 37 correctly predictsthe ionization energy. 38,39 BEB cross sections for Pt andstill. 14 Our calculated (BEB) relative cross sections at

  15. The Pd-catalyzed fluorination of (hetero)aryl bromides and triflates

    E-Print Network [OSTI]

    Milner, Phillip J

    2015-01-01

    Chapter 1: This chapter details mechanistic work regarding the reductive elimination of electron-rich aryl fluorides from L-Pd(Ar)F species. An unexpected dearomatization/arylation process of Pd(II) complexes bearing bulky ...

  16. Development and Applications of Pd Catalysts for C-N Cross-Coupling Reactions

    E-Print Network [OSTI]

    Fors, Brett P

    2011-01-01

    Chapter 1 A procedure for forming a highly active Pd(0) catalyst from Pd(OAc) 2, water, and biarylphosphine ligands has been developed. This protocol generates a catalyst system, which exhibits excellent reactivity and ...

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

    Office of Scientific and Technical Information (OSTI)

    Quantitative EDS Analysis of Nanometer-Scale CoreShell PdRh Structures. Citation Details In-Document Search Title: Quantitative EDS Analysis of Nanometer-Scale CoreShell PdRh...

  18. Comparative and Functional Genomics of Rhodococcus opacus PD630 for Biofuels Development

    E-Print Network [OSTI]

    Sinskey, Anthony J.

    Comparative and Functional Genomics of Rhodococcus opacus PD630 for Biofuels Development Jason W and Functional Genomics of Rhodococcus opacus PD630 for Biofuels Development. PLoS Genet 7(9): e1002219. doi:10

  19. 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.

  20. Monopole Strength in Ni-58 

    E-Print Network [OSTI]

    Youngblood, David H.; Lui, YW.

    1991-01-01

    Differential cross-section data from 0-degrees to 8-degrees for inelastic scattering of 129 MeV alpha particles exciting Ni-58 in the region of 14-22 MeV have been analyzed to explore the existence of monopole strength at approximately E(x) = 17 Me...

  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. 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.

  3. 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.

  4. Elevated expression of ERK 2 in human tumor cells chronically treated with PD98059

    SciTech Connect (OSTI)

    Kanda, Shigeru [Department of Molecular Microbiology and Immunology, Division of Endothelial Cell Biology, Nagasaki University Graduate School of Biomedical Science, Nagasaki (Japan)]. E-mail: skanda-jua@umin.net; Kanetake, Hiroshi [Department of Urology, Nagasaki University Graduate School of Biomedical Science, Nagasaki (Japan); Miyata, Yasuyoshi [Department of Urology, Nagasaki University Graduate School of Biomedical Science, Nagasaki (Japan)

    2006-07-14

    We examined the effect of chronic exposure of tumor cells to a mitogen-activated protein kinase/extracellular signal-regulated kinases (ERK) kinase inhibitor, PD98059, on cell proliferation was investigated. Human renal carcinoma cells (ACHN) and prostatic carcinoma cells (DU145) were cultured in the presence of PD98059 for more than 4 weeks (denoted ACHN (PD) cells and DU145 (PD) cells, respectively) and proliferation and signal transduction pathways were examined. PD98059 significantly inhibited the proliferation of parental cells. However, PD98059 failed to inhibit proliferation of ACHN (PD) and DU145 (PD) cells significantly. Expression of ERK 1 and 2 was elevated in these cells. These phenotypes were reversible. Downregulation of ERK 2, but not ERK 1, by small interfering RNA significantly inhibited the proliferation of ACHN (PD) and DU145 (PD) cells. Taken together, chronic exposure of tumor cells to PD98059 induced elevated expression of ERK 2, which was associated with decreased sensitivity of cellular proliferation to PD98059.

  5. Approved Module Information for PD4002, 2014/5 Module Title/Name: Product Design Innovation Module Code: PD4002

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for PD4002, 2014/5 Module Title/Name: Product Design Innovation Module: . MSc Product Design Innovation. Available to Exchange Students? Not Specified Module Learning to initiate Innovation or Entrepreneurial skills to create product or enterprise proposals and development

  6. Approved Module Information for PD4008, 2014/5 Module Title/Name: Innovation Business Development Module Code: PD4008

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    in which available: MSc Product Design Innovation. MSc Product Design Enterprise. BEng/MEng Mechanical product and identify potential development include: Innovative design features-possible patents, marketApproved Module Information for PD4008, 2014/5 Module Title/Name: Innovation Business Development

  7. 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 part or all of the surface in the less sulfur resistant {beta} phase.

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

    SciTech Connect (OSTI)

    Abiona, Adurafimihan A.; Kemp, Williams; Timmers, Heiko [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, UNSW Canberra, PO Box 7916, Canberra BC 2610 (Australia)

    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.

  9. PT-symmetric quantum state discrimination

    E-Print Network [OSTI]

    Carl M. Bender; Dorje C. Brody; Joao Caldeira; Bernard K. Meister

    2010-11-08

    Suppose that a system is known to be in one of two quantum states, $|\\psi_1 > $ or $|\\psi_2 >$. If these states are not orthogonal, then in conventional quantum mechanics it is impossible with one measurement to determine with certainty which state the system is in. However, because a non-Hermitian PT-symmetric Hamiltonian determines the inner product that is appropriate for the Hilbert space of physical states, it is always possible to choose this inner product so that the two states $|\\psi_1 > $ and $|\\psi_2 > $ are orthogonal. Thus, quantum state discrimination can, in principle, be achieved with a single measurement.

  10. Finite plasticity in $P^T P$

    E-Print Network [OSTI]

    Diego Grandi; Ulisse Stefanelli

    2015-09-29

    We discuss a finite-plasticity model based on the symmetric tensor $P^T P$ instead of the classical plastic strain $P$. Such a model structure arises from assuming that the material behavior is invariant with respect to frame transformations of the intermediate configuration. The resulting variational model is lower-dimensional, symmetric, and based solely on the reference configuration. We discuss the existence of energetic solutions both at the material-point level and for the quasistatic boundary-value problem. These solutions are constructed as limits of time discretizations. Eventually, the linearization of the model for small deformations is ascertained via a rigorous evolutive-$\\Gamma$-convergence argument.

  11. Passive $\\mathcal{PT}$-symmetric couplers without complex optical potentials

    E-Print Network [OSTI]

    Lee, Yi-Chan; Chuang, You-Lin; Hsieh, Min-Hsiu; Lee, Ray-Kuang

    2015-01-01

    In addition to the implementation of parity-time ($\\mathcal{PT}$)-symmetric optical systems by carefully and actively controlling the gain and loss, we show that a $2\\times 2$ $\\mathcal{PT}$-symmetric Hamiltonian has a unitarily equivalent representation without complex optical potentials in the resulting optical coupler. Through the Naimark dilation in operator algebra, passive $\\mathcal{PT}$-symmetric couplers can thus be implemented with a refractive index of real values and asymmetric coupling coefficients. This opens up the possibility to implement general $\\mathcal{PT}$-symmetric systems with state-of-the-art asymmetric slab waveguides, dissimilar optical fibers, or cavities with chiral mirrors.

  12. 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...

  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. Stabilization of Pt monolayer catalysts under harsh conditions...

    Office of Scientific and Technical Information (OSTI)

    Stabilization of Pt monolayer catalysts under harsh conditions of fuel cells Citation Details In-Document Search This content will become publicly available on May 21, 2016 Title:...

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

    SciTech Connect (OSTI)

    Brammer, Travis

    2011-08-15

    High temperature alloys are essential to many industries that require a stable material to perform in harsh oxidative environments. Many of these alloys are suited for specific applications such as jet engine turbine blades where most other materials would either melt or oxidize and crumble (1). These alloys must have a high melting temperature, excellent oxidation resistance, good creep resistance, and decent fracture toughness to be successfully used in such environments. The discovery of Ni based superalloys in the 1940s revolutionized the high temperature alloy industry and there has been continued development of these alloys since their advent (2). These materials are capable of operating in oxidative environments in the presence of combustion gases, water vapor and at temperatures around 1050 C. Demands for increased f uel efficiency, however, has highlighted the need for materials that can be used under similar atmospheres and at temperatures in excess of 1200 C. The current Ni based superalloys are restricted to lower temperatures due to the presence of a number of low melting phases that result in softening of the alloys above 1000 C. Therefore, recent research has been aimed at exploring and developing newer alloy systems that can meet the escalating requirements. This thesis comprises a part of such an effort. The motivation of this work is to develop a novel high temperature alloy system that shows improved performance at higher temperatures than the currently employed alloys. The desired alloy should be in accordance with the requirements established in the National Energy Technology Laboratory (NETL) FutureGen program having an operating temperature around 1300 C. Alloys based on NiAl offer significant potential payoffs as structural materials in gas turbine applications due to a unique range of physical and mechanical properties. Alloying additions to NiAl could be used to further improve the pertinent properties that currently limit this system from 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 testing are still needed. Two major issues yet to be resolved are the low fracture toughn

  16. 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.

  17. 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.

  18. Fishing for Narrow Dibaryons in pd->pX Reaction

    E-Print Network [OSTI]

    L. V. Fil'kov; V. L. Kashevarov; E. S. Konobeevski; M. V. Mordovskoy; S. I. Potashev; V. A. Simonov; V. M. Skorkin; S. V. Zuev

    2000-09-15

    An analysis of experimental data, obtained at the Linear Accelerator of INR, is carried out with the aim of searching for supernarrow dibaryons in the reactions pd->p+X and pd->p+pX_1. Dibaryons with masses 1904\\pm 2, 1926\\pm 2, and 1942\\pm 2 MeV have been observed in M_{X} missing mass spectra. In M_{X_1} missing mass spectra, the peaks have been found at M_{X_1}=966\\pm 2, 986\\pm 2, and 1003\\pm 2 MeV. These values of M_{X_1} coincide with the ones obtained by a simulation of a decay of the dibaryons into \\gamma+pn. The analysis of the data obtained leads to the conclusion that the observed dibaryons are supernarrow dibaryons, the decay of which into two nucleons is forbidden by the Pauli exclusion principle. A possible interpretation of exited nucleon states with small masses is suggested.

  19. Engineering the Martensitic Transformation Hysteresis of Ni-Rich NiTi Alloys 

    E-Print Network [OSTI]

    Franco, Brian Eelan

    2014-12-18

    The shape memory behavior in NiTi alloys can be exploited for a wide variety of applications that require active materials. The application dictates the transformation temperatures and hysteresis of the alloy. NiTi alloys ...

  20. Transformation Induced Fatigue of Ni-Rich NiTi Shape Memory Alloy Actuators 

    E-Print Network [OSTI]

    Schick, Justin Ryan

    2011-02-22

    In this work the transformation induced fatigue of Ni-rich NiTi shape memory alloys (SMAs) was investigated. The aerospace industry is currently considering implementing SMA actuators into new applications. However, before ...

  1. 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.

  2. AK Hartmann, Thermodynamik und Statistische Physik 103 Auf Koexistenzkurve p(T): 1(T, p(T)) -2(T, p(T)) = 0

    E-Print Network [OSTI]

    Hartmann, Alexander K.

    AK Hartmann, Thermodynamik und Statistische Physik 103 26.1.2006 Auf Koexistenzkurve p(T): µ1(T, p(T)) - µ2(T, p(T)) = 0 totale Ableitung d dT = 0: 0 ! = dµ1(T) dT - dµ2(T) dT = µ1 T p - µ2 T p + µ1 p T - µ2 p T dp dT = 1 N S - 1 N V dp dT (S = 0, V = 0) dp dT = S V = Ql TV (14.3) Gleichung von Clausius

  3. Measurement of the (gamma,n) reaction rates of the nuclides 190Pt, 192Pt, and 198Pt in the astrophysical gamma-process

    E-Print Network [OSTI]

    K. Vogt; P. Mohr; M. Babilon; J. Enders; T. Hartmann; C. Hutter; T. Rauscher; S. Volz; A. Zilges

    2001-03-07

    The nucleosynthesis of heavy neutron-deficient nuclei in a stellar photon bath at the temperatures relevant for the astrophysical gamma process was investigated. In order to derive (gamma,n) cross sections and reaction rates, the stellar photon bath was simulated by the superposition of several bremsstrahlung spectra with different endpoint energies. As a first test for this method, the (gamma,n) reaction rates of the platinum isotopes 190Pt, 192Pt, and 198Pt were derived. The results are compared to other experimental data and theoretical calculations.

  4. Simultaneous determination of Ni-63 and Ni-59 in radioactive wastes by liquid scintillation spectrometry 

    E-Print Network [OSTI]

    Kim, Esther Miyeun

    1988-01-01

    SIMULTANEOUS DETERMINATION OF Ni-63 AND Ni-59 IN RADIOACTIVE WASTES BY LIQUID SCINTILLATION SPECTROMETRY A Thesis by ESTHER MIYEUN KIM Submitted to the Office of Graduate Studies of Texas AgtM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1988 Major Subject: Health Physics SIMULTANEOUS DETERMINATION OF Ni-63 AND Ni-59 IN RADIOACTIVE WASTES BY LIQUID SCINTILLATION SPECTROMETRY A Thesis by ESTHER MIYEUN KIM Approved as to style...

  5. ³Ni² 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...

  6. Approved Module Information for AM30PD, 2014/5 Module Title/Name: Partial Differential Equations Module Code: AM30PD

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for AM30PD, 2014/5 Module Title/Name: Partial Differential Equations Module Code: AM30PD School: Engineering and Applied Science Module Type: Standard Module New Module? No Module Credits: 20 Module Management Information Module Leader Name David Saad Email Address saadd

  7. Reactivity and stability of platinum and platinum alloy catalysts toward the oxygen reduction reaction 

    E-Print Network [OSTI]

    Calvo, Sergio Rafael

    2009-05-15

    Density functional theory (DFT) is used to study the reactivity of Pt and Pt-M (M: Pd, Co, Ni, V, and Rh) alloy catalysts towards the oxygen reduction reaction (ORR) as a function of the alloy overall composition and surface atomic distribution...

  8. 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}

  9. 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.

  10. 44 (2007-5) FT-ICR Pt,Co

    E-Print Network [OSTI]

    Maruyama, Shigeo

    Resonance) mass spectrometer. Metal clusters were generated by a pulsed laser-vaporization supersonic 02.0 s 1.0×10-8 Torr Pt 4 Pt Cluster Source Gate Valve Gas Addition 6 Tesla Superconducting Feedthrough Probe Laser Ionization Laser 100 cm Turbopump Cluster Source Gate Valve Gas Addition 6 Tesla

  11. Ordinary versus PT-symmetric ?³ 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 ig?³ 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 g?³ quantum field theory with those of the PT-symmetric ig?³ quantum field theory. It is shown that while the conventional g?³ theory in d=6 dimensions is asymptotically free, the ig?³ theory is like a g?? theory in d=4 dimensions; it is energetically stable, perturbatively renormalizable, and trivial.« less

  12. Research on Pd film deposition rate calculation and simulation based on TiZrV/Pd film coating experiment

    E-Print Network [OSTI]

    Wang, Jie; Xu, Yanhui; Wang, Yong

    2015-01-01

    The vacuum chamber of accelerator storage ring need clean ultra-high vacuum environment. TiZrV getter film which was deposited on interior wall of vacuum chamber, can realize distributed pumping, effectively improve the vacuum degree and reduce the longitudinal gradient. But accumulation of pollutants such as N2, O2, will decrease the adsorption ability of non-evaporable getter (NEG), which leads to the reduction of NEG lifetime. Therefore, NEG thin film coated with a layer of Pd which has high diffusion rate and absorption ability for H2, can extend the service life of NEG, and improve the pumping rate of H2 at the same time. With argon as discharge gas, magnetron sputtering method was adopted to prepare TiZrV-Pd film in long straight pipe. According to the experimental results of the scanning electron microscope (SEM), deposition rates of TiZrV-Pd films were analyzed under different deposition parameters, the magnetic field strength, the gas flow rate, discharge current, discharge voltage and working pressu...

  13. Magnetic structure near the Co/NiO(001) interface

    E-Print Network [OSTI]

    Arenholz, Elke

    2008-01-01

    are perpendicular to the NiO moments, hence demonstrating2+ L 3,2 XA spectra and NiO domain pattern (inset). SpectraThe 100 directions of the NiO(001) plane and the orientation

  14. Nonlinear switching and solitons in PT-symmetric photonic systems

    E-Print Network [OSTI]

    Suchkov, Sergey V; Huang, Jiahao; Dmitriev, Sergey V; Lee, Chaohong; Kivshar, Yuri S

    2015-01-01

    One of the challenges of the modern photonics is to develop all-optical devices enabling increased speed and energy efficiency for transmitting and processing information on an optical chip. It is believed that the recently suggested Parity-Time (PT) symmetric photonic systems with alternating regions of gain and loss can bring novel functionalities. In such systems, losses are as important as gain and, depending on the structural parameters, gain compensates losses. Generally, PT systems demonstrate nontrivial non-conservative wave interactions and phase transitions, which can be employed for signal filtering and switching, opening new prospects for active control of light. In this review, we discuss a broad range of problems involving nonlinear PT-symmetric photonic systems with an intensity-dependent refractive index. Nonlinearity in such PT symmetric systems provides a basis for many effects such as the formation of localized modes, nonlinearly-induced PT-symmetry breaking, and all-optical switching. Nonl...

  15. Graphdiyne as a Promising Substrate for Stabilizing Pt Nanoparticle Catalyst

    E-Print Network [OSTI]

    Lin, Zheng-Zhe

    2015-01-01

    At present, Pt nanoparticle catalysts in fuel cells suffer from aggregation and loss of chemical activity. In this work, graphdiyne, which has natural porous structure, was proposed as substrate with high adsorption ability to stabilize Pt nanoparticles. Using multiscale calculations by ab initio method and the ReaxFF potential, geometry optimizations, molecular dynamics simulations, Metropolis Monte Carlo simulations and minimum energy paths calculations were performed to investigate the adsorption energy and the rates of desorption and migration of Pt nanoparticles on graphdiyne and graphene. According to the comparison between graphdiyne and graphene, it was found that the high adsorption ability of graphdiyne can avoid Pt nanoparticle migration and aggregation on substrate. Then, simulations indicated the potential catalytic ability of graphdiyne-Pt-nanoparticle system to the oxygen reduction reaction in fuel cells. In summary, graphdiyne should be an excellent material to replace graphite or amorphous ca...

  16. 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 [Institute of Physical Chemistry, University of Vienna, A-1090 Wien, Waehringerstrasse 42 (Austria); Rogl, Peter, E-mail: peter.franz.rogl@univie.ac.a [Institute of Physical Chemistry, University of Vienna, A-1090 Wien, Waehringerstrasse 42 (Austria); Salamakha, Leonid; Bauer, Ernst; Hilscher, Gerfried; Michor, Herwig [Institute of Solid State Physics, Vienna University of Technology, A-1040 Wien (Austria); Giester, Gerald [Institute of Mineralogy and Crystallography, University of Vienna, Althanstr. 14, A-1090 Wien (Austria)

    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 binary Yb{sub 5}Pd{sub 2-x} (Mn{sub 5}C{sub 2}-type) was confirmed from X-ray single crystal data and a slight defect on the Pd site (x=0.06) was established. The three structures tau{sub 1}-Ce{sub 6}Pd{sub 47-x}B{sub 6}, tau{sub 2}-CePd{sub 8}B{sub 2-x} and tau{sub 3}-Ce{sub 3}Pd{sub 25-x}B{sub 8-y} are related and can be considered as the packings of fragments observed in Nd{sub 2}Fe{sub 14}B structure with different stacking of common structural blocks. Physical properties for Yb{sub 2}Pd{sub 13.6}B{sub 5} (temperature dependent specific heat, electrical resistivity and magnetization) yielded a predominantly Yb-4f{sup 13} electronic configuration, presumably related with a magnetic instability below 2 K. Kondo interaction and crystalline electric field effects control the paramagnetic temperature domain. - Graphical Abstract: Crystal structure of CePd{sub 8}B{sub 2-x}.

  17. 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.

  18. 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.

  19. Giant Quadrupole-Resonance in Ni Isotopes 

    E-Print Network [OSTI]

    Youngblood, David H.; Lui, YW; Garg, U.; Peterson, R. J.

    1992-01-01

    VOLUME 45, NUMBER 5 MAY 1992 Giant quadrupole resonance in Ni isotopes D. H. Youngblood and Y.-%. Lui Texas A&M UniUersity, College Station, Texas 77843 U. Garg University of Notre Dame, South Bend, Indiana 46556 R. J. Peterson University... (%) 58+12 76+14 78+14 90+16 Cp 0.80+0.04 0.84+0.04 0.82+0. 12 1.05+0. 10 2174 YOUNGBLOOD, LUI, GARG, AND PETERSON 45 1000 100 60Ni(n, n') E = 129 MeV 1 000 100 58Ni(n, n') 10 10 100 z' 1000 64Ni(n, n') 1OO~y 64 Ni 100 10 I s & & I...

  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 and the dehydrogenation ethylidene to ethylidyne. This is consistent with experimental results which suggest only the predominant hydrogenation path involving the sequential addition of hydrogen to form vinyl and ethylene exists over the Pd-Ag alloys. Ag enhances the desorption of ethylene and hydrogen from the surface thus limiting their ability to undergo subsequent reactions. The simulated apparent activation barriers were calculated to be 32-44 kJ/mol on Pd(111) and 26-31 kJ/mol on Pd-Ag/Pd(111) respectively. The reaction was found to be essentially first order in hydrogen over Pd(111) and Pd-Ag/Pd(111) surfaces. The results reveal that increases in the hydrogen partial pressure increase the activity but decrease ethylene selectivity over both Pd and Pd-Ag/Pd(111) surfaces. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  1. Overcoming Hydrocarbon Inhibition on Pd-based Diesel Oxidation Catalysts with Rational Catalyst Design Approach

    Broader source: Energy.gov [DOE]

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

  2. Research on the secondary electron yield of tizrv-pd thin film coatings

    E-Print Network [OSTI]

    Wang, Jie; Zhang, Bo; Wang, Yong; Wei, Wei

    2015-01-01

    In particle accelerators, the build-up of electron cloud may have important influence on beam quality. Especially for the positron and proton accelerators, massive electrons lead to electron cloud, which affects the stability, energy, emittance and beam life adversely. A secondary electron emission (SEE) measurement system has been designed and used to study the SEE of palladium (Pd), TiZrV and TiZrV-Pd with an independently adjustable energy from 50 eV to 5 keV. Here, we obtained the characteristics of the SEE from Pd, TiZrV and TiZrV-Pd film coatings with different thickness under ultrahigh-vacuum (UHV) conditions. Moreover, the maximum secondary electron yield (SEY), {\\delta}max, of the Pd, TiZrV and TiZrV-Pd film coatings under different primary electron doses were obtained, respectively. Finally, the variation of the secondary electron yield with the incident electron energy will be discussed for Pd, TiZrV and TiZrV-Pd thin film coatings. Low SEY is a new advantage of TiZrV-Pd films, besides high H2 abso...

  3. Controlled nanoporous Pt morphologies by varying deposition parameters

    SciTech Connect (OSTI)

    Misra, Amit [Los Alamos National Laboratory; Nastasi, Michael A [Los Alamos National Laboratory; Baldwin, J Kevin [Los Alamos National Laboratory; Goodwin, Peter M [Los Alamos National Laboratory; Bhattacharyya, Dhriti [Los Alamos National Laboratory; Antoniou, Antonia [GEROGIA INSTITUTE OF TECH

    2009-01-01

    Typically, dealloying of an alloy can result in an open cell nanoporous structure of the least electrochemically active element. Here, we show that a wider range of nanoporous structures is possible by controlling the composition and deposition parameters of the as-synthesized alloy as a way to provide sites for preferential etching. We demonstrate this by synthesizing nanoporous platinum (np-Pt) through electrochemical dealloying in aqueous HF from co-sputtered Pt{sub x}Si{sub 1-x} amorphous films. For increased Pt fraction of the amorphous alloy, silicon dissolution is favored along pre-existing features of the amorphous film (e.g. column boundaries or surface asperities). The resulting np-Pt depends on the manner in which silicon is preferentially removed. In addition to the expected isotropic open cell structure, columnar and Voronoi (radial) np-Pt are observed. A processing-structure map is developed to correlate np-Pt morphology to the initial composition and thickness of the amorphous Pt{sub x}Si{sub 1-x} film and the negative substrate bias used in magnetron sputtering.

  4. 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.

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

    SciTech Connect (OSTI)

    Page, Katharine [Materials Department and Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States); Schade, Christina S. [Materials Department and Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States); Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitaet Mainz, Duesbergweg 10-14, Mainz D55099 (Germany); Zhang, Jinping [Materials Department and Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States); Chupas, Peter J.; Chapman, Karena W. [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Proffen, Thomas [Los Alamos National Laboratory, Lujan Neutron Scattering Center LANSCE-12, MS H805, Los Alamos, NM 87545 (United States); Cheetham, Anthony K. [Materials Department and Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States); Seshadri, Ram [Materials Department and Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States)], E-mail: seshadri@mrl.ucsb.edu

    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.

  6. 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.

  7. 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 ? (H/Pd???0.03) ? ? (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 ? ? ? phase transition points towards the advantage of using Pd-alloy nanoparticles in applications requiring long term and repeated hydrogen cycling.

  8. Enthalpy of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys

    SciTech Connect (OSTI)

    Witusiewicz, V.T.; Sommer, F.

    2000-04-01

    Since the Al-Cu-Ni-Zr system is a basis for the production of bulk amorphous materials by rapid solidification techniques from the liquid state, it is of great scientific interest to determine the partial and the integral thermodynamic functions of liquid and undercooled liquid alloys. Such data, as was pointed out previously, are important in order to understand their extremely good glass-forming ability in multicomponent metallic systems as well as for processing improvements. In order to measure the thermodynamic properties of the Al-Cu-Ni-Zr quaternary, it is necessary to have reliable thermochemical data for its constituent canaries and ternaries first. In a series of articles, the authors have reported in detail the thermodynamic properties of liquid Al-Cu, Al-Ni, Cu-Ni, Cu-Zr, Al-Zr, Al-Cu-Ni, and Al-Cu-Zr alloys. This article deals with the direct calorimetric measurements of the partial and the integral enthalpies of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys and the heat capacity of liquid Ni{sub 26}Zr{sub 74}. In a subsequent article, the authors will present similar data for the liquid ternary Al-Ni-Zr and for the liquid quaternary Al-Cu-Ni-Zr alloys.

  9. 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}

  10. 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.

  11. Cyclin-G-associated kinase modifies alpha-synuclein expression levels and toxicity in Parkinson's disease: results from the GenePD Study

    E-Print Network [OSTI]

    Dumitriu, Alexandra

    Although family history is a well-established risk factor for Parkinson's disease (PD), fewer than 5% of PD cases can be attributed to known genetic mutations. The etiology for the remainder of PD cases is unclear; however, ...

  12. Supporting Information Monodisperse PtRu Nanoalloy on Carbon

    E-Print Network [OSTI]

    Kwak, Juhyoun

    Advanced Institute of Science and Technology, Daejeon, 305-701, Korea. E-mail: joontpark.0%, Junsei) at 80 °C for 10 h. The resulting PtRu/Vc catalyst was collected by centrifugation, washed

  13. Thermoelectric effect in very thin film Pt/Au thermocouples

    SciTech Connect (OSTI)

    Salvadori, M.C.; Vaz, A.R.; Teixeira, F.S.; Cattani, M.; Brown,I.G.

    2006-01-10

    The thickness dependence of the thermoelectric power of Pt films of variable thickness on a reference Au film has been determined for the case when the Pt film thickness, t, is not large compared to the charge carrier mean free path, {ell}, that is, t/{ell}. Pt film thicknesses down to 2.2 nm were investigated. We find that {Delta}S{sub F} = S{sub B}-S{sub F} (where S{sub B} and S{sub F} are the thermopowers of the Pt bulk and film, respectively) does not vary linearly as 1/t as is the case for thin film thermocouples when the film thickness is large compared to the charge carrier mean free path.

  14. $\\mathcal{PT}$-Symmetry-Breaking Chaos in Optomechanics

    E-Print Network [OSTI]

    Lü, Xin-You; Ma, Jin-Yong; Wu, Ying

    2015-01-01

    We demonstrate a $\\mathcal{PT}$-symmetry-breaking chaos in optomechanical system (OMS), which features an ultralow driving threshold. In principle, this chaos will emerge once a driving laser is applied to the cavity mode and lasts for a period of time. The driving strength is inversely proportional to the starting time of chaos. This originally comes from the dynamical enhancement of nonlinearity by field localization in $\\mathcal{PT}$-symmetry-breaking phase ($\\mathcal{PT}$BP). Moreover, this chaos is switchable by tuning the system parameters so that a $\\mathcal{PT}$-symmetry phase transition occurs. This work may fundamentally broaden the regimes of cavity optomechanics and nonlinear optics. It offers the prospect of exploring ultralow-power-laser triggered chaos and its potential applications in secret communication.

  15. Spectromicroscopy study of interfacial Co/NiO(001)

    E-Print Network [OSTI]

    van der Laan, Gerrit

    2011-01-01

    study of interfacial Co/NiO(001) G. van der Laan, 1 N. D.the Co moments. The Ni moments in NiO prefer to be orienteda component of the moments in the NiO collinear to the Co.

  16. Semiconductor to Metal to Half-Metal Transition in Pt-Embedded Zigzag Graphene Nanoribbons

    E-Print Network [OSTI]

    Krasheninnikov, Arkady V.

    Semiconductor to Metal to Half-Metal Transition in Pt-Embedded Zigzag Graphene Nanoribbons Xiaohui properties of Pt-embedded zigzag graphene nanoribbons (Pt-ZGNRs) are investigated using density-functional theory calculations. It is found that Pt-ZGNRs exhibit a semiconductor-metal-half-metal transition

  17. 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.

  18. Pd and Ag metal-silicate partitioning applied to Earth differentiation and core-mantle exchange

    E-Print Network [OSTI]

    Mcdonough, William F.

    Pd and Ag metal-silicate partitioning applied to Earth differentiation and core-mantle exchange metallic sulfide and liquid silicate under plausible magma ocean conditions constrains potential core 107 Ag content and the origin of observed Pd and Ag mantle abundances. DPd metallic sulfide / silicate

  19. 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.

  20. 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).

  1. 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.

  2. 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.

  3. 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).

  4. Ethanol Oxidation on the Ternary Pt–Rh–SnO2/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.

  5. Rationalization of Au concentration and distribution in AuNi...

    Office of Scientific and Technical Information (OSTI)

    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...

  6. 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.

  7. 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.

  8. Microscopic return point memory in Co/Pd multilayer films

    SciTech Connect (OSTI)

    Seu, K.A.; Su, R.; Roy, S.; Parks, D.; Shipton, E.; Fullerton, E.E.; Kevan, S.D.

    2009-10-01

    We report soft x-ray speckle metrology measurements of microscopic return point and complementary point memory in Co/Pd magnetic films having perpendicular anisotropy. We observe that the domains assemble into a common labyrinth phase with a period that varies by nearly a factor of two between initial reversal and fields near saturation. Unlike previous studies of similar systems, the ability of the film to reproduce its domain structure after magnetic cycling through saturation varies from loop to loop, from position to position on the sample, and with the part of the speckle pattern used in the metrology measurements. We report the distribution of memory as a function of field and discuss these results in terms of the reversal process.

  9. 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}.

  10. Ethane dehydrogenation on Pt/Mg(Al)O and PtSn/Mg(Al)O catalysts Vladimir Galvita, Georges Siddiqi, Pingping Sun, Alexis T. Bell *

    E-Print Network [OSTI]

    Bell, Alexis

    Ethane dehydrogenation on Pt/Mg(Al)O and PtSn/Mg(Al)O catalysts Vladimir Galvita, Georges Siddiqi(Al)O Dehydrogenation Alkanes Alkenes a b s t r a c t The dehydrogenation of ethane to ethene on Sn-promoted Pt for dehydrogenation, and the formation of coke. The origins of methane, the primary byproduct of ethane

  11. Fig. 1. Magnetic hysteresis of NiO-doped NiF2 conversion materials

    E-Print Network [OSTI]

    Siegel, Paul H.

    member with CMRR, is leading her group to design, optimize and develop new materials for energy storage materials for higher energy lithium ion batteries (at least double the energy density of today's technologyFig. 1. Magnetic hysteresis of NiO-doped NiF2 conversion materials CMRR Newsletter Shirley Meng

  12. Electronic circuits having NiAl and Ni.sub.3 Al substrates

    DOE Patents [OSTI]

    Deevi, Seetharama C. (Midlothian, VA); Sikka, Vinod K. (Oak Ridge, TN)

    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.

  13. Antiproton Production in Ni+ni Collisions at 1.85 Gev/nucleon 

    E-Print Network [OSTI]

    LI, GQ; Ko, Che Ming.

    1994-01-01

    Antiproton production in Ni+Ni collisions at 1.85 GeV/nucleon is studied in the relativistic Vlasov-Uehling-Uhlenbeck model. The self-energies of the antiproton are determined from the nucleon self-energies by the G-parity transformation. Also...

  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. 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.

  16. 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.

  17. 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.

  18. Understanding the Nucleation and Growth of Metals on TiO2: Co Compared to Au, Ni, and Pt

    E-Print Network [OSTI]

    Henkelman, Graeme

    The Co-TiO2 system has also been used for other industrially relevant catalytic processes, including the steam reforming of ethanol,24 preferential oxidation of CO in hydrogen,25 and oxidative dehydrogenation

  19. 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.

  20. 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.

  1. Antiferromagnetic Kondo lattice in the layered compound CePd1–xBi? and comparison to the superconductor LaPd1–xBi?

    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–xBi? with the tetragonal ZrCuSi?-type structure was obtained from excess Bi flux. Magnetic susceptibility data of CePd1–xBi? 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?¹ K?² obtained from specific-heat measurement suggests a moderate Kondo effect in CePd1–xBi?. 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–xBi? 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

  2. Level densities and thermodynamical properties of Pt and Au isotopes

    E-Print Network [OSTI]

    F. Giacoppo; F. L. Bello Garrote; L. A. Bernstein; D. L. Bleuel; T. K. Eriksen; R. B. Firestone; A. Görgen; M. Guttormsen; T. W. Hagen; B. V. Kheswa; M. Klintefjord; P. E. Koehler; A. C. Larsen; H. T. Nyhus; T. Renstrøm; E. Sahin; S. Siem; T. Tornyi

    2014-11-28

    The nuclear level densities of $^{194-196}$Pt and $^{197,198}$Au below the neutron separation energy have been measured using transfer and scattering reactions. All the level density distributions follow the constant-temperature description. Each group of isotopes is characterized by the same temperature above the energy threshold corresponding to the breaking of the first Cooper pair. A constant entropy excess $\\Delta S=1.9$ and $1.1$ $k_B$ is observed in $^{195}$Pt and $^{198}$Au with respect to $^{196}$Pt and $^{197}$Au, respectively, giving information on the available single-particle level space for the last unpaired valence neutron. The breaking of nucleon Cooper pairs is revealed by sequential peaks in the microcanonical caloric curve.

  3. 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 direction—suitable for perpendicular magnetic recording media applications—are 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.

  4. PT symmetry and spontaneous symmetry breaking in a microwave billiard

    E-Print Network [OSTI]

    S. Bittner; B. Dietz; U. Guenther; H. L. Harney; M. Miski-Oglu; A. Richter; F. Schaefer

    2011-12-02

    We demonstrate the presence of parity-time (PT) symmetry for the non-Hermitian two-state Hamiltonian of a dissipative microwave billiard in the vicinity of an exceptional point (EP). The shape of the billiard depends on two parameters. The Hamiltonian is determined from the measured resonance spectrum on a fine grid in the parameter plane. After applying a purely imaginary diagonal shift to the Hamiltonian, its eigenvalues are either real or complex conjugate on a curve, which passes through the EP. An appropriate basis choice reveals its PT symmetry. Spontaneous symmetry breaking occurs at the EP.

  5. The structure of supersymmetry in ${\\cal PT}$ symmetric quantum mechanics

    E-Print Network [OSTI]

    D. Bazeia; Ashok Das; L. Greenwood; L. Losano

    2009-03-17

    The structure of supersymmetry is analyzed systematically in ${\\cal PT}$ symmetric quantum mechanical theories. We give a detailed description of supersymmetric systems associated with one dimensional ${\\cal PT}$ symmetric quantum mechanical theories. We show that there is a richer structure present in these theories compared to the conventional theories associated with Hermitian Hamiltonians. We bring out various properties associated with these supersymmetric systems and generalize such quantum mechanical theories to higher dimensions as well as to the case of one dimensional shape invariant potentials.

  6. Direct photons at low $p_{T}$ measured in PHENIX

    E-Print Network [OSTI]

    D. Peressounko

    2007-02-12

    Direct photon spectra measured at small $p_T$ in p+p, d+Au and Au+Au collisions at $\\sqrt{s_{NN}}=200$ GeV are presented. Several measurement techniques including statistical subtraction, tagging, and internal and external conversion were applied and found to produce consistent results. The p+p and d+Au results are found to be in very good agreement with pQCD predictions over the entire $p_T$ range. No excess of direct photons in Au+Au collisions with respect to binary scaled d+Au data is observed within systematic errors.

  7. 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.

  8. Characterization of Pt-based Transition Metal Alloy Electrodes for PEFC

    SciTech Connect (OSTI)

    Uebayashi, M.; Sato, Y.; Jeyadevan, B.; Tohji, K. [Graduate School of Environmental Studies, Tohoku Univ., Aramaki aza Aoba, Aoba-ku, Sendai (Japan); Sawada, Y. [Sumitomo Corporation, 1-8-11, Harumi, Chuo-ku, Tokyo 104-8610 (Japan); Itoh, T. [Center for Interdisciplinary Research, Tohoku Univ., Aramaki aza Aoba, Aoba-ku, Sendai (Japan)

    2007-03-20

    Pt metal is generally used as electrocatalyst in polymer electrolyte fuel cells (PEFC). However, the catalytic action of Pt anode is obstructed by the adsorption of CO gas molecules on to their surface and consequently the efficiency of the fuel cell decreases. Moreover, the activity of PEFC deteriorates even if the presence of CO is as low as 100 ppm. In this paper, attempts are being made to replace the Pt with Pt-based transition metal alloys such as PtFe and PtCo to overcome the above problem and also to improve the activity of fuel cells. The PtFe/C and PtCo/C necessary for the preparation of the electrodes were synthesized by depositing PtFe and PtCo particles synthesized using the polyol process on to the surface ketjenblack. From the results of cyclic voltammetry, we could confirm that PtFe/C could be used as an alternate material of Pt/C. However, Fe ions get eluted in the electrolyte. Thus, the study that can control the elution of Fe ion is necessary. Also in case of PtCo/C, we could confirm that Co ion doesn't get to elute, however the hydrogen oxidation reaction current is quite low.

  9. A New Biarylphosphine Ligand for the Pd-Catalyzed Synthesis of Diaryl Ethers under Mild Conditions

    E-Print Network [OSTI]

    Salvi, Luca

    A new bulky biarylphosphine ligand (L8) has been developed that allows the Pd-catalyzed C–O cross-coupling of a wide range of aryl halides and phenols under milder conditions than previously possible. A direct correlation ...

  10. The mechanism of the Pd-catalyzed formation of coumarins: A theoretical study

    E-Print Network [OSTI]

    Nedd, S; Alexandrova, AN; Alexandrova, AN

    2015-01-01

    indicated 20 that the palladium(II) acetate (Pd(OAc) 2 )the ethynyl group by the palladium catalyst was PCCP, 2014,the CMD mechanism for the palladium-catalyzed intramolecular

  11. Synthesis of 5,5-Disubstituted Butenolides Based on a Pd-Catalyzed ?-Arylation Strategy

    E-Print Network [OSTI]

    Hyde, Alan M.

    Methods for the construction of quaternary carbon centers are of great interest to synthetic chemists due to their presence in natural products. Development of the Pd-catalyzed arylation of butenolides with high selectivity ...

  12. A Multi-Ligand Based Pd Catalyst for C–N Cross-Coupling Reactions

    E-Print Network [OSTI]

    Fors, Brett P.

    An alternative approach to catalyst development, which led to a Pd catalyst based on two biarylphosphine ligands for C?N cross-coupling reactions, is reported. By effectively being able to take the form of multiple catalysts ...

  13. In situ Microscopy Studies of Growth Kinetics of Monolayer Graphene on Pd(111)

    E-Print Network [OSTI]

    Mok, Hoi Sing

    2013-01-01

    transport in suspended graphene," Phys Rev Lett 101 (9),Growth Kinetics of Monolayer Graphene on Pd(111),"X. Weng, "Top-Gated Epitaxial Graphene FETs on Si-Face SiC

  14. Method and Pd/V2 O5 device for H2 detection

    DOE Patents [OSTI]

    Liu, Ping (San Diego, CA); Tracy, C. Edwin (Golden, CO); Pitts, J. Roland (Lakewood, CO); Smith, II, R. Davis (Golden, CO); Lee, Se-Hee (Lakewood, CO)

    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.

  15. Herz-, Thorax-, Transplantations-und Gefchirurgie PD Dr. A. R. Simon Hannover Thoracic Transplant Program

    E-Print Network [OSTI]

    Manstein, Dietmar J.

    /Ventilations ModiPerfsuions/Ventilations Modi · Maintenance Mode ­ Kontinuierliche pulsatile Perfusion mit warmem Transplant Program PD Dr. A. R. Simon 8 MAINTENANCE MODEMAINTENANCE MODE Ventilation im Equilibrium Gas mix Austauschmodul Pump flow 1.5 L/min Beatmung mi

  16. Comparative and Functional Genomics of Rhodococcus opacus PD630 for Biofuels Development

    E-Print Network [OSTI]

    Ghiviriga, Ion

    The Actinomycetales bacteria Rhodococcus opacus PD630 and Rhodococcus jostii RHA1 bioconvert a diverse range of organic substrates through lipid biosynthesis into large quantities of energy-rich triacylglycerols (TAGs). ...

  17. Process design and modeling for the production of triacylglycerols (TAGs) in Rhodococcus opacus PD630

    E-Print Network [OSTI]

    Miller, Neidi

    2012-01-01

    The oleaginous microorganism Rhodococcus opacus PD630 was used to study the characteristics and kinetics of the accumulation of triacylglycerols (TAGs) in cells. In this process, accumulation of TAG is stimulated when a ...

  18. The mechanism of the Pd-catalyzed formation of coumarins: A theoretical study

    E-Print Network [OSTI]

    Nedd, S; Alexandrova, AN; Alexandrova, AN

    2015-01-01

    deprotonation (CMD) mechanism. This journal is © The RoyalRSC Publishing ARTICLE Mechanism of Pd-catalyzed FormationN. Alexandrova* a,b The mechanism of formation of coumarin

  19. Benchmark Problem: A PK/PD Model and Safety Constraints for Anesthesia Delivery

    E-Print Network [OSTI]

    Mitchell, Ian

    : · A series of related models of the effect of propofol infusion on depth of hypnosis. · A quantitative Plasma Slow Peripheral Propofol Infusion u Delay E ect Site Hill Equation E ect Cp Ce C C PK Model PD

  20. Rapid generation of molecular complexity under Pd(II) and Rh(III) catalysis 

    E-Print Network [OSTI]

    Kujawa, Szymon

    2015-11-26

    1. Enantioselective Pd(II)-Catalysed Nucleophilic Additions of 2- Alkylazaarenes The first project deals with enantio- and diastereoselective palladium(II)-catalysed nucleophilic additions of 2-alkylazaarenes to N-Boc ...

  1. 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.

  2. Energy absorption in Ni-Mn-Ga/ polymer composites

    E-Print Network [OSTI]

    Feuchtwanger, Jorge

    2006-01-01

    In recent years Ni-Mn-Ga has attracted considerable attention as a new kind of actuator material. Off-stoichiometric single crystals of Ni2MnGa can regularly exhibit 6% strain in tetragonal martensites and orthorhombic ...

  3. Carbon Nanotube Growth Using Ni Catalyst in Different Layouts

    E-Print Network [OSTI]

    Nguyen, H. Q.

    Vertically aligned carbon nanotubes have been grown using Ni as catalyst by plasma enhanced chemical vapor deposition system (PECVD) in various pre-patterned substrates. Ni was thermally evaporated on silicon substrates ...

  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. Pd?Cd11–? (0.21???0.51)–a partly disordered ?-brass type phase and Pd?.???Cd?.??? -a ?-brass related incommensurate phase in the palladium–cadmium system

    SciTech Connect (OSTI)

    Jana, Partha Pratim, E-mail: Partha.Jana@polymat.lth.se [CAS Chemical Centre, Lund University, Getingevägen 60, Box 124, Lund SE-22100 (Sweden); Lidin, Sven, E-mail: Sven.Lidin@polymat.lth.se [CAS Chemical Centre, Lund University, Getingevägen 60, Box 124, Lund SE-22100 (Sweden)

    2013-05-01

    The Cd rich part of the Cd–Pd 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=[(½, ½, 0, 0); (½, 0, ½, 0 ); (0, ½, ½, 0 )] with the fundamental cell dimensions a=4.687(2) Å, b=10.000(1) Å, c=14.140(2) Å, 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 palladium–cadmium 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.

  7. Oxidation of Methanol on 2nd and 3rd Row Group VIII Transition Metals (Pt, Ir, Os, Pd, Rh, and Ru): Application to Direct Methanol

    E-Print Network [OSTI]

    Goddard III, William A.

    this problem; however, extracting molecular hydrogen from a liquid fuel requires a reformer. This greatly parameters for com- mercial use are now achievable with modern catalytic formula- tions and cell designs.1 by a proton- exchange membrane such as Nafion. Platinum-based electrodes demonstrate the highest catalytic

  8. 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

  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. On non-acceptibility of variational based calculation in $PT$ symmetrized complex Harmonic oscillators: Direct study

    E-Print Network [OSTI]

    Biswanath Rath

    2015-06-09

    We notice through a direct calculation that any variational based calculation on $PT$ symmetrized complex Harmonic Oscillator can lead to breakdown of $PT$ symmetry condition on real spectra. Two different types of oscillators have been tested yielding an uniform conclusion.

  11. Pt-free, Perovskite-based Lean NOx Trap Catalysts | Department...

    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...

  12. Oxygen Adsorption on Au–Ni(111) Surface Alloys

    E-Print Network [OSTI]

    Lee, Jae-Gook

    Molecular O[subscript 2] dissociates upon interaction with a Ni(111) surface, as the spatial and energetic overlap between the Ni 3d electrons and the O[subscript 2] antibonding orbitals is quite favorable. On a Au–Ni(111) ...

  13. High Temperature coatings based on {beta}-NiAI

    SciTech Connect (OSTI)

    Severs, Kevin

    2012-07-10

    High temperature alloys are reviewed, focusing on current superalloys and their coatings. The synthesis, characerization, and oxidation performance of a NiAl–TiB{sub 2} composite are explained. A novel coating process for Mo–Ni–Al alloys for improved oxidation performance is examined. The cyclic oxidation performance of coated and uncoated Mo–Ni–Al alloys is discussed.

  14. OpenWordNet-PT: A Project Report Alexandre Rademaker

    E-Print Network [OSTI]

    representation de- veloped for OpenWordnet-PT. We high- light our efforts to extend the coverage of our resource, or that caminh~ao (truck) is related to these words as well in that they all share a common more general hy

  15. Rubrik 30/34 pt Berthold Akzidenz Bold

    E-Print Network [OSTI]

    Rubrik 30/34 pt Berthold Akzidenz Bold EPOK ­ Centre for Organic Food and Farming Research Agenda for Organic Agriculture 2013 Research challenges and knowledge requirements for organic food and farming Maria: SLU, EPOK ­ Centre for Organic Food and Farming Layout: Pelle Fredriksson, SLU, EPOK Photographs

  16. Giant monopole strength in Ni-58 

    E-Print Network [OSTI]

    Lui, YW; Clark, HL; Youngblood, David H.

    2000-01-01

    The strength distribution of the giant monopole resonance in Ni-58 has been measured from E-x = 10 to 35 MeV using small-angle scattering of 240-MeV alpha particles. E0 strength corresponding to 74(-12)(+22)% of the E0 EWSR was found between E-x...

  17. Optimization of out-of-plane magnetized Co/Pt multilayers with resistive buffer layers

    E-Print Network [OSTI]

    Emori, Satoru

    Ta oxide (TaOx) is investigated as a resistive buffer layer for the growth of high-quality Co/Pt multilayers with perpendicular magnetic anisotropy (PMA). The Pt/(Co/Pt)3 films grown on TaOx buffer layers exhibit stronger ...

  18. Femtosecond Near-Infrared Laser Desorption of Multilayer Benzene on Pt{111}: A Molecular Newton's Cradle?

    E-Print Network [OSTI]

    Levis, Robert J.

    Femtosecond Near-Infrared Laser Desorption of Multilayer Benzene on Pt{111}: A Molecular Newton desorption of multilayers of benzene adsorbed on Pt{111} are reported as a function of laser intensity, which by a thermally assisted DIET excitation in the chemisorbed layer, and followed by energy transfer from the Pt-benzene

  19. Growth of Pt nanoparticle for proton-exchange-membrane fuel cells by

    E-Print Network [OSTI]

    PEMFC Growth of Pt nanoparticle for proton-exchange-membrane fuel cells at anode side of a polymer electrolyte membrane (PEM) fuel cell. With a Pt loading of 25 g-Pt/cm2 , current of the electrochemical test result and fuel cell performance agree with each other. Key word : Pulsed laser deposition

  20. A Ni/surface-modified Diamond Composite Electroplating Coating on Superelastic NiTi Alloy as Potential Dental Bur Design

    E-Print Network [OSTI]

    Zheng, Yufeng

    A Ni/surface-modified Diamond Composite Electroplating Coating on Superelastic NiTi Alloy: Composite Electroplating; Surface-modified Diamond Particles; Interfacial Adhesion; NiTi alloy; Dental Bur into nickel coating, and its shank made of stainless steel. There are strong demands from the dentist

  1. In Situ XAS of Ni-W Hydrocracking Catalysts

    SciTech Connect (OSTI)

    Yang, N. [Argonne National Laboratory, Argonne, IL 60439 (United States); Mickelson, G. E.; Greenlay, N.; Bare, Simon R. [UOP LLC, Des Plaines, IL 60016 (United States); Kelly, S. D. [EXAFS Analysis, Bolingbrook, IL 60440 (United States)

    2007-02-02

    Ni-W based catalysts are very attractive in hydrotreating of heavy oil due to their high hydrogenation activity. In the present research, two catalyst samples, prepared by different methods, that exhibit significant differences in activity were sulfided in situ, and the local structure of the Ni and W were studied using X-ray absorption spectroscopy (XAS). The Ni XANES spectra were analyzed using a linear component fitting, and the EXAFS spectra of the WS2 platelets in the sulfided catalysts were modeled. The Ni and W are fully sulfided in the higher activity sample, and there are both unsulfided Ni ({approx}25%) and W (<10%) in the lower activity sample.

  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 experiments

  3. 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.

  4. 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.

  5. Impact of surface roughness of Au core in Au/Pd coreeshell nanoparticles toward formic acid oxidation e Experiment and

    E-Print Network [OSTI]

    Liu, Fuqiang

    on hollow Au. Au/Pd coreeshell nanoparticles with smooth Au surface by adding Na2SO3 demonstrated highly concentrations of Na2SO3 solution. It was found that the higher concentration of Na2SO3 that was used and decrease the catalytic abilities. The Au/Pd NPs synthesized using 0 M Na2SO3 (denoted as 0 M-Au/Pd NPs

  6. Pd-Catalyzed Dynamic Kinetic Enantioselective Arylation of Silylphosphines Vincent S. Chan, Robert G. Bergman,* and F. Dean Toste*

    E-Print Network [OSTI]

    Toste, Dean

    G. Bergman,* and F. Dean Toste* Department of Chemistry, UniVersity of California, BerkeleyPd-Catalyzed Dynamic Kinetic Enantioselective Arylation of Silylphosphines Vincent S. Chan, Robert

  7. 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.

  8. Deposition and characterization of TiZrV-Pd thin films by dc magnetron sputtering

    E-Print Network [OSTI]

    Wang, Jie; Xu, Yan-Hui; Wei, Wei; Fan, Le; Pei, Xiang-Tao; Hong, Yuan-Zhi; Wang, Yong

    2015-01-01

    TiZrV film is mainly applied in the ultra-high vacuum pipe of storage ring. Thin film coatings of palladium which was added onto the TiZrV film to increase the service life of nonevaporable getters and enhance pumping speed for H2, was deposited on the inner face of stainless steel pipes by dc magnetron sputtering using argon gas as the sputtering gas. The TiZrV-Pd film properties were investigated by atomic force microscope (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-Ray Diffraction (XRD). The grain size of TiZrV and Pd film were about 0.42~1.3 nm and 8.5~18.25 nm respectively. It was found that the roughness of TiZrV films was small, about 2~4 nm, for Pd film it is large, about 17~19 nm. PP At. % of Pd in TiZrV/Pd films varied from 86.84 to 87.56 according to the XPS test results.

  9. Pd menbrane having improved H.sub.2-permeance, and method of making

    DOE Patents [OSTI]

    Vanderspurt, Thomas Henry (Glastonbury, CT); She, Ying (Worcester, MA); Dardas, Zissis (Worcester, MA); Walker, Craig (South Glastonbury, CT); MacLeod, James D. (Vernon, CT)

    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.

  10. Collectivity evolution in the neutron-rich Pd isotopes towards the N=82 shell closure

    E-Print Network [OSTI]

    Wang, H; Takeuchi, S; Matsushita, M; Doornenbal, P; Motobayashi, T; Steppenbeck, D; Yoneda, K; Baba, H; Caceres, L; Dombradi, Zs; Kobayashi, K; Kondo, Y; Lee, J; Li, K; Liu, H; Minakata, R; Nishimura, D; Otsu, H; Sakaguchi, S; Sakurai, H; Scheit, H; Sohler, D; Sun, Y; Tian, Z; Tanaka, R; Togano, Y; Vajta, Zs; Yang, Z; Yamamoto, T; Ye, Y; Yokoyama, R

    2013-01-01

    The neutron-rich, even-even 122,124,126Pd isotopes has been studied via in-beam gamma-ray spectroscopy at the RIKEN Radioactive Isotope Beam Factory. Excited states at 499(9), 590(11), and 686(17) keV were found in the three isotopes, which we assign to the respective 2+ -> 0+ decays. In addition, a candidate for the 4+ state at 1164(20) keV was observed in 122Pd. The resulting Ex(2+) systematics are essentially similar to those of the Xe (Z=54) isotopic chain and theoretical prediction by IBM-2, suggesting no serious shell quenching in the Pd isotopes in the vicinity of N=82.

  11. EBSD study on crystallographic texture and microstructure development of cold-rolled FePd alloy

    SciTech Connect (OSTI)

    Lin, Hung-Pin; Ng, Tin-San [Department of Materials Science and Engineering, National Cheng-Kung University, No. 1, University Road, Tainan 701, Taiwan (China); Kuo, Jui-Chao, E-mail: jckuo@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng-Kung University, No. 1, University Road, Tainan 701, Taiwan (China); Chen, Yen-Chun [Department of Materials Science and Engineering, National Cheng-Kung University, No. 1, University Road, Tainan 701, Taiwan (China); Chen, Chun-Liang [Department of Materials Science and Engineering, I-Shou University, No. 1 Sec. 1 Syuecheng Road, Kaohsiung 840, Taiwan (China); Ding, Shi-Xuan [Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, No. 70, Lienhai Road, Kaohsiung 804, Taiwan (China); Research Center for Physical Properties and Microstructure of Metals, National Sun Yat-Sen University, No. 70, Lienhai Road, Kaohsiung 804, Taiwan (China)

    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.

  12. Hydrogen production from methanol decomposition over Pt/Al2O3 and ceria promoted Pt/Al2O3 catalysts

    E-Print Network [OSTI]

    Gulari, Erdogan

    Hydrogen production from methanol decomposition over Pt/Al2O3 and ceria promoted Pt/Al2O3 catalysts-based catalysts in the production of hydrogen from methanol through catalytic decomposition favorably to a commercial copper-based catalyst. The hydrogen selectivity is exceptionally high at 99

  13. 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.

  14. 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.

  15. Posttest TRAC-PD2/MOD1 predictions for FLECHT SEASET test 31504. [PWR

    SciTech Connect (OSTI)

    Booker, C.P.

    1982-01-01

    TRAC-PD2/MOD1 is a publicly released version of TRAC that is used primarily to analyze large-break loss-of-coolant accidents in pressurized-water reactors (PWRs). TRAC-PD2 can calculate, among other things, reflood phenomena. TRAC posttest predictions are compared with test 31504 reflood data from the Full-Length Emergency Core Heat Transfer (FLECHT) System Effects and Separate Effects Tests (SEASET) facility. A false top-down quench is predicted near the top of the core and the subcooling is underpredicted at the bottom of the core. However, the overall TRAC predictions are good, especially near the center of the core.

  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. 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.

  18. Approved Module Information for PD3003, 2014/5 Module Title/Name: Professional Preparation for Industry

    E-Print Network [OSTI]

    Neirotti, Juan Pablo

    Approved Module Information for PD3003, 2014/5 Module Title/Name: Professional Preparation for Industry (Business Focus) Module Code: PD3003 School: Engineering and Applied Science Module Type: Standard Module New Module? No Module Credits: 20 Module Management Information Module Leader Name Christian

  19. 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.

  20. Oxidation-resistant, solution-processed plasmonic Ni nanochain...

    Office of Scientific and Technical Information (OSTI)

    solution-processed plasmonic Ni nanochain-SiOsub x (x < 2) selective solar thermal absorbers Citation Details In-Document Search Title: Oxidation-resistant,...

  1. Fusion of radioactive $^{132}$Sn with $^{64}$Ni

    E-Print Network [OSTI]

    J. F. Liang; D. Shapira; J. R. Beene; C. J. Gross; R. L. Varner; A. Galindo-Uribarri; J. Gomez del Campo; P. A. Hausladen; P. E. Mueller; D. W. Stracener; H. Amro; J. J. Kolata; J. D. Bierman; A. L. Caraley; K. L. Jones; Y. Larochelle; W. Loveland; D. Peterson

    2007-04-05

    Evaporation residue and fission cross sections of radioactive $^{132}$Sn on $^{64}$Ni were measured near the Coulomb barrier. A large sub-barrier fusion enhancement was observed. Coupled-channel calculations including inelastic excitation of the projectile and target, and neutron transfer are in good agreement with the measured fusion excitation function. When the change in nuclear size and shift in barrier height are accounted for, there is no extra fusion enhancement in $^{132}$Sn+$^{64}$Ni with respect to stable Sn+$^{64}$Ni. A systematic comparison of evaporation residue cross sections for the fusion of even $^{112-124}$Sn and $^{132}$Sn with $^{64}$Ni is presented.

  2. 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.

  3. 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.

  4. 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 ease the adsorption of 4-chlorophenol, hydroxyl, and water molecules to the surface. Thus, n-NiO/p-NiO single crystalline catalysts can be introduced as a potent candidate to remediate the environmental pollution.

  5. 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.

  6. Power Densities Using Different Cathode Catalysts (Pt and CoTMPP)

    E-Print Network [OSTI]

    and PTFE) in Single Chamber Microbial Fuel Cells S H A O A N C H E N G , H O N G L I U , A N D B R U C E performed better as a Pt binder thanpoly(tetrafluoroethylene)(PTFE).Replacingtheprecious- metal Pt catalyst that replacement of the Nafion binder used for the cathode catalyst (0.5 mg of Pt cm-2) with PTFE reduced

  7. SF 6432-NI (04-95)

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation of Fe(II) byMultidayAlumni > The EnergyRyanPhysics6/14/11 Page 1 of6432-NI

  8. Ni(II) Salts and 2-Propanol Effect Catalytic Reductive Coupling of Epoxides and Alkynes

    E-Print Network [OSTI]

    Beaver, Matthew G.

    A Ni-catalyzed reductive coupling of alkynes and epoxides using Ni(II) salts and simple alcohol reducing agents is described. Whereas previously reported conditions relied on Ni(cod)2 and Et3B, this system has several ...

  9. Continuous spin reorientation transition in epitaxially grown antiferromagnetic NiO thin films

    E-Print Network [OSTI]

    Li, J.

    2011-01-01

    along certain crystal axis [e.g. , NiO(100)]. Thusthe r 2 p S z 2, NiO ( dMgO ) / S NiO should be an approximation in the small limit.

  10. Solution-based thermodynamic modeling of the Ni-Al-Mo system...

    Office of Scientific and Technical Information (OSTI)

    (Al,Mo,Ni)0.75(Al,Mo,Ni)0.25. Thus, -fcc and -Ni3Al are modeled with a single Gibbs free energy function with appropriate treatment of the chemical ordering contribution. In...

  11. 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, E-mail: tgkim1@korea.ac.kr [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    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.

  12. Crystal structure and physical properties of the novel stannide Yb3Pd2Sn2

    E-Print Network [OSTI]

    Ryan, Dominic

    on the Yb-Pd-Sn system was published [1], motivated by the intriguing physical properties of some (pieces, 99.993 % Yb/TREM purity, Smart Elements GmbH, Vienna, Austria), palladium (foil, 99.95 mass microscopy (SEM) and electron probe micro-analysis (EPMA) based on energy dispersive X-ray spectroscopy

  13. On the promotional effect of Pd2 on the propene-assisted decomposition of NO3

    E-Print Network [OSTI]

    (2006) 201-214" #12;2 Abstract:1 The Selective Catalytic Reduction (SCR) of NOx assisted by propene. This study shows that the incorporation of Pd6 to CZ greatly promotes the reduction of NO in the presence of C3H6. These catalysts display7 very stable deNOx activity even in the presence of 1.7% water

  14. Crystalline monolayer surface of liquid AuCuSiAgPd: Metallic glass former

    E-Print Network [OSTI]

    Pershan, Peter S.

    Crystalline monolayer surface of liquid Au­Cu­Si­Ag­Pd: Metallic glass former S. Mechler,1,a E of a two-dimensional crystalline monolayer phase for temperatures of up to about 50 K above the eutectic freezing in which a 2D crystalline phase forms within a sur- face segregated monolayer of liquid Ga alloys

  15. In situ reflection high energy electron diffraction study of dehydrogenation process of Pd coated Mg nanoblades

    E-Print Network [OSTI]

    Wang, Gwo-Ching

    and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA Received 23 March 2008; accepted,2 Hydrogen has been con- sidered as one of the promising alternative energy resources due to its abundanceIn situ reflection high energy electron diffraction study of dehydrogenation process of Pd coated

  16. PdAu/C catalysts prepared by plasma sputtering for the electro-oxidation of glycerol

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    prepared by plasma deposition of Au and Pd atoms on a carbon diffusion layer. Atomic composition and metal low metallic film thickness made TEM and XRD characterizations difficult to perform, therefore electro-oxidation is an important research domain because of its implication in fuel cell development

  17. Hydrogen adsorption on Pd/TiFe (110) surface S.E. Kulkovaa

    E-Print Network [OSTI]

    Kim, Jai Sam

    Hydrogen adsorption on Pd/TiFe (110) surface S.E. Kulkovaa , S.V. Eremeeva,b,*, V.E. Egorushkinc February 2003 by E.L. Ivchenko Abstract Adsorption of hydrogen on the TiFe (110) surface covered. Electronic band structure 1. Introduction The TiFe alloy is an excellent material for hydrogen storage [1

  18. 8 THE AMERICAN SOCIETY FOR CELL BIOLOGY PRESS BOOK 2004 arkinson's disease (PD) was named

    E-Print Network [OSTI]

    Feng, Jian

    as a progressive neurodegenerative disease. Parkinson's is caused by the selective death of neurons that produce-radical-damaged tubulin. In this fight, mutated parkin apparently arrives unarmed. Parkinson's Disease: Shootout8 THE AMERICAN SOCIETY FOR CELL BIOLOGY PRESS BOOK 2004 P arkinson's disease (PD) was named

  19. Parkinson's disease (PD) is characterized by the rela-tively selective degeneration of dopaminergic neurons in

    E-Print Network [OSTI]

    Feng, Jian

    Parkinson's disease (PD) is characterized by the rela- tively selective degeneration into a stiff, hollow tube. Each Microtubule: A Common Target for Parkin and Parkinson's Disease Toxins JIAN performed on twins (Tanner and others 1999), reveal strong environmental connections to the disease

  20. Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the

    E-Print Network [OSTI]

    Shorter, James

    Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the loss motor and cognitive problems. Although the disease was first described in 1817 (Parkinson, 2002), few treatments exist today. These treatments do not target the cause of the disease and instead aim to increase

  1. Single Pd atoms in activated carbon fibers and their contribution to hydrogen storage 5

    E-Print Network [OSTI]

    Pennycook, Steve

    Single Pd atoms in activated carbon fibers and their contribution to hydrogen storage 5 Cristian I surface area carbon materials for hydrogen storage continues to attract interest because predicted high potential for hydrogen storage on metal-decorated carbon supports, the experimental

  2. Mathematical modelling of curtain coating RJ Dyson, PD Howell, CJW Breward, P Herdman and J Brander

    E-Print Network [OSTI]

    Breward, Chris J W

    Mathematical modelling of curtain coating RJ Dyson, PD Howell, CJW Breward, P Herdman and J Brander a simple mathematical model for the fluid flow in the curtain coat- ing process, exploiting the small coating Curtain coating is an industrial process, traditionally used to coat photographic film, which

  3. 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.

  4. Room temperature hydrogen detection using Pd-coated GaN nanowires Wantae Lim,1

    E-Print Network [OSTI]

    Ural, Ant

    Room temperature hydrogen detection using Pd-coated GaN nanowires Wantae Lim,1 J. S. Wright,1 B. P vapor deposition were employed as gas sensors for detection of hydrogen at concentrations from 200­1500 ppm in N2 at 300 K. Palladium coating of the wires improved the sensitivity by a factor of up to 11

  5. Physical mechanism of reectance inversion in hydrogen gas sensor with Pd/PVDF structures

    E-Print Network [OSTI]

    Mandelis, Andreas

    of an optical ®ber. It was found that the re¯ectance of the palladium ®lm decreased when hydrogen gas] reported a hydrogen sensor based on the optical generation of surface plasmons in palladium/nickel alloysPhysical mechanism of re¯ectance inversion in hydrogen gas sensor with Pd/PVDF structures Chinhua

  6. Where do the H atoms reside in PdHx systems? RICCARDA CAPUTO1,2

    E-Print Network [OSTI]

    Alavi, Ali

    into account the quantum nature of the dissolved hydrogen. 1. Introduction Palladium­hydrogen systems have been of hydrogen, Pd seems to have peculiar chemical­physical properties that make it a highly attractive metal for hydrogen absorp- tion and dissolution. According to the Encyclopaedia Britannica, `. . . at 80 C and one

  7. AcqGuide70pt4.doc | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematics AndBerylliumDepartment of Energy8pt1.doc&#0;47.1 (June 2004) 1

  8. PT-symmetric quantum systems with positive P

    E-Print Network [OSTI]

    Miloslav Znojil; Hendrik B. Geyer

    2012-01-24

    A new version of PT-symmetric quantum theory is proposed and illustrated by an N-site-lattice Legendre oscillator. The essence of the innovation lies in the replacement of parity P (serving as an indefinite metric in an auxiliary Krein space) by its non-involutory alternative P(positive)=Q>0 playing the role of a positive-definite nontrivial metric in an auxiliary, redundant, unphysical Hilbert space. It is shown that the QT-symmetry of this form remains appealing and technically useful.

  9. AcqGuide38pt1.doc | Department of Energy

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirley Ann JacksonDepartment| DepartmentAL/FAL 99-01 More5,Achieving 30% Renewable8pt1.doc&#0;

  10. 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 100–250?°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.

  11. P(t) Dependence of Transverse Flow in Relativistic Heavy-Ion Collisions 

    E-Print Network [OSTI]

    Li, Bao-An; Ko, Che Ming; Li, GQ.

    1996-01-01

    and th was thus informatio R(pt)[( number o ~opposite the projectil spirit to tha bevalac/si gate whethe transverse state of th heavy-ion transversel x n transverse s ~ f!# /T , ~2! azimuthal e mo- the reac- 1 /ptdpt) e flow.... It is shown that the pt e flow that is complementary to that obtained from g features of using the pt dependence to study formed in relativistic heavy-ion collisions are demon- z relativistic transport model ~ART! @15# we show that the ra- tio R(pt...

  12. 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}.

  13. 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.

  14. 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.

  15. 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.

  16. Luminescence properties of the hybrid Si-Ni nanoparticles system

    E-Print Network [OSTI]

    Lalayan, A A; Movsesyan, H A

    2015-01-01

    The luminescence properties of the colloidal hybrid Si - Ni nanoparticles system fabricated in the pure water by pulsed laser ablation is considered. The red-shifted photoluminescence of this system because of the Stark effect in the Coulomb field of the charged Ni nanoparticles has been registered in the blue range of the spectrum.

  17. 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.

  18. In situ XAS of Ni-W hydrocracking catalysts.

    SciTech Connect (OSTI)

    Yang, N.; Mickelson, G. E.; Greenlay, N.; Kelly, S. D.; Bare, S. R.; UOP LLC; EXAFS Analysis

    2007-01-01

    Ni-W based catalysts are very attractive in hydrotreating of heavy oil due to their high hydrogenation activity. In the present research, two catalyst samples, prepared by different methods, that exhibit significant differences in activity were sulfided in situ, and the local structure of the Ni and W were studied using X-ray absorption spectroscopy (XAS). The Ni XANES spectra were analyzed using a linear component fitting, and the EXAFS spectra of the WS{sub 2} platelets in the sulfided catalysts were modeled. The Ni and W are fully sulfided in the higher activity sample, and there are both unsulfided Ni ({approx}25%) and W (<10%) in the lower activity sample.

  19. Hydrides of CeNi/sub 5/, MmNi/sub 5/, Ca/sub 0/ /sub 2/(Ce/sub 0/ /sub 65/Mm/sub 0/ /sub 35/)/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Ce/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Mm/sub 0/ /sub 8/Ni/sub 5/, and mixed CeNi/sub 5//MmNi/sub 5/

    SciTech Connect (OSTI)

    Lakner, J.F.; Chow, T.S.

    1982-09-01

    Six intermetallic alloys (CeNi/sub 5/, MmNi/sub 5/, Ca/sub 0/ /sub 2/(Ce/sub 0/ /sub 65/Mm/sub 0/ /sub 35/)/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Ce/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Mm/sub 0/ /sub 8/Ni/sub 5/, and a mixed alloy, CeNi/sub 5//MmNi/sub 5/) were investigated with respect to their suitability to provide high hydrogen capacity and their potential for use in providing substantial hydrogen pressure at both low and high temperatures. A second phase of our investigation dealt with ball-milling and hydriding and dehydriding cycles to produce fine particles for use in hydride powder transfer studies. A summary of several Van't Hoff plots is also included for hydride-forming alloys.

  20. 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), ultraviolet–visible (UV–vis) 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.

  1. 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.

  2. Simple and Versatile Route to the Synthesis of Anisotropic Bimetallic Core-Shell and Monometallic Hollow Nanostructures: Ag (AgCl)-Pt Core-Shell Nanocubes and Pt Nanoboxes

    E-Print Network [OSTI]

    Tan, Yen Nee

    We report herewith a simple and versatile route for the preparation of anisotropic Ag(AgCl)-Pt core-shell nanocubes and Pt nanoboxes. The core-shell nanocubes were first synthesized through the simultaneous reduction method ...

  3. Performance of plasma sputtered Fuel Cell electrodes with ultra-low Pt M. Cavarroca

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Performance of plasma sputtered Fuel Cell electrodes with ultra-low Pt loadings M. Cavarroca , A. Abstract Ultra-low Pt content PEMFC electrodes have been manufactured using magnetron co- sputtering cell; Plasma sputtering deposition; ultra low platinum loading * Corresponding author: Fax: +33 2 38 41

  4. 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.

  5. Mechanism of O2 Activation and Methanol Production by (Di(2-pyridyl)methanesulfonate)PtII

    E-Print Network [OSTI]

    Goddard III, William A.

    Mechanism of O2 Activation and Methanol Production by (Di(2- pyridyl)methanesulfonate)PtII Me observed for the SN2 functionalization to form methanol by two isomeric (dpms)PtIV Me(OH)2 complexes, one conversion of methane to methanol at low temper- ature is crucial for transportation of shale gas produced

  6. PT symmetric pseudo-perturbation recipe; an imaginary cubic oscillator with spikes

    E-Print Network [OSTI]

    Omar Mustafa; Miloslav Znojil

    2002-08-24

    The pseudo-perturbation shifted-l expansion technique PSLET is shown applicable in the non-Hermitian PT-symmetric context. The construction of bound states for several PT-symmetric potentials is presented, with special attention paid to V(r) = ir^3-alpha sqrt(ir) oscillators.

  7. Novel Pt/Mg(In)(Al)O catalysts for ethane and propane dehydrogenation Pingping Sun a

    E-Print Network [OSTI]

    Iglesia, Enrique

    Novel Pt/Mg(In)(Al)O catalysts for ethane and propane dehydrogenation Pingping Sun a , Georges and propane dehydrogenation reactions are strongly dependent on the bulk In/Pt ratio. For both reactants to alkene was nearly 100%. Coke deposition was observed after catalyst use for either ethane or propane

  8. Development of PZT and PZN-PT Based Unimorph Actuators for Micromechanical Flapping Mechanisms

    E-Print Network [OSTI]

    Fearing, Ron

    mechanisms, Cox et al. [7] developed four-bar and five-bar flexure mechanisms inte- grated with unimorphDevelopment of PZT and PZN-PT Based Unimorph Actuators for Micromechanical Flapping Mechanisms- terization of unimorph actuators for a microaerial flap- ping mechanism. PZT-5H and PZN-PT are investigated

  9. CO2 sticking on Pt(111); the role of kinetic energy and internal degrees of freedom

    E-Print Network [OSTI]

    Persson, Mats

    CO2 sticking on Pt(111); the role of kinetic energy and internal, S-412 96, G"oteborg, Sweden Abstract CO2 adsorbed measurements of non-dissociative sticking coefficient, S0, of CO2 on the Pt(111) surfac* *e

  10. 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.}

  11. The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa

    SciTech Connect (OSTI)

    Özduran, Mustafa; Turgut, Kemal; Arikan, Nihat; ?yigör, 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. 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 HClO? at 23°C, a CTR as low as 0.04 ? cm² was obtained with only 20 ?g cm?² Pt and 11 ?g 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 « less

  13. Oblikoslovje v panonski nare?ni skupini

    E-Print Network [OSTI]

    Zorko, Zinka

    2010-01-01

    glagole: nes?, neseši, neset?; nesev?, neseta, nesete; nesem?, nesete, nes?t?; za atematske glagole: jesm?, jesi, jest?; jesv?, jesta, jeste; jesm?, jeste, s?t?. Slovenski knjižni jezik – tematska spregatev: nes-em, -eš, -e; -va, -ta, -ta; -mo, -te, -jo...; atematska spregatev: sem, si, je; sva, sta, sta; smo, ste, so. Prekmurš?ina (vsi glagoli se spregajo po temati?nem vzorcu): ne?s?:n, ne?s?:š, ne?s?:; ne?s?:va (m. sp.), ne?s?:ve (ž. sp.), ne?s?:ta, ne?s?:ta; ne?s?:mo, ne?s?:te, ne?s?:jo; ?sån, ?si, ?je; s...

  14. 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.

  15. Elastic stability and electronic structure of pyrite type PtN2: Ahard semiconductor

    SciTech Connect (OSTI)

    Yu, Rong; Zhan, Qian; Zhang, Xiao-Feng

    2006-08-29

    The elastic properties and electronic structure of PtN2 withthe pyrite structure (PtN2(C2)) were studied with first-principlescalculations. The crystal structure is demonstrated to be elasticallystable with a lower energy than the metastable fluorite structureproposed before. The calculated shear modulus of 214 GPa suggests thatPtN2(C2) is harder than some well known hard materials such as TiN andSiC. The high elastic moduli are attributed to a stacking ofcorner-shared PtN6 octahedra bonded by strong N-N covalent bonding. Incontrast to the metallic fluorite-type phase, PtN2(C2) is semiconductingwith an indirect band gap.

  16. ADSORPTION AND BONDING OF BUTANE AND PENTANE ON THE Pt(111) CRYSTAL SURFACES. EFFECTS OF OXYGEN TREATMENTS AND DEUTERIUM PREADSORPTION

    E-Print Network [OSTI]

    Salmeron, M.

    2012-01-01

    ADSORPTION AND BONDING OF BUTANE AND PENTANE ON THE .Pt(111)ADSORPTION AND BONDING OF BUTANE AND PENTANE ON THE Pt(lll)adsorption characteristics of butane and pentane on the (

  17. Physical and biological properties of a Pt(ll) complex of a beta-diketiminate ligand with pendant quinoline arms

    E-Print Network [OSTI]

    Hope, Jennifer M

    2012-01-01

    A monoanionic, tetradentate [beta]-diketiminate (BDI) ligand with pendant quinoline arms, BDIQQH was coordinated to Pt(II) to yield the square-planar complex [Pt(BDIQQ)]CI. This complex was characterized by NMR spectroscopy, ...

  18. 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.

  19. 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.

  20. Phase transition in PT symmetric active plasmonic systems

    E-Print Network [OSTI]

    Mattheakis, M; Molina, M I; Tsironis, G P

    2015-01-01

    Surface plasmon polaritons (SPPs) are coherent electromagnetic surface waves trapped on an insulator-conductor interface. The SPPs decay exponentially along the propagation due to conductor losses, restricting the SPPs propagation length to few microns. Gain materials can be used to counterbalance the aforementioned losses. We provide an exact expression for the gain, in terms of the optical properties of the interface, for which the losses are eliminated. In addition, we show that systems characterized by lossless SPP propagation are related to PT symmetric systems. Furthermore, we derive an analytical critical value of the gain describing a phase transition between lossless and prohibited SPPs propagation. The regime of the aforementioned propagation can be directed by the optical properties of the system under scrutiny. Finally, we perform COMSOL simulations verifying the theoretical findings.

  1. Metamaterials, Point Interactions, Phase-Conjugation, and PT-Symmetry

    E-Print Network [OSTI]

    Ali Mostafazadeh

    2015-08-07

    We express the boundary conditions for TE and TM waves at the interfaces of an infinite planar slab of homogeneous metamaterial as certain point interactions and use them to compute the transfer matrix of the system. This allows us to demonstrate the omnidirectional reflectionlessness of Veselago's slab for waves of arbitrary wavelength, reveal the translational and reflection symmetry of this slab, explore the laser threshold condition and coherent perfect absorption for active negative-index metamaterials, introduce a point interaction modeling phase-conjugation, determine the corresponding antilinear transfer matrix, and offer a simple proof of the equivalence of Veselago's slab with a pair of parallel phase-conjugating plates. We also study the connection between certain optical setups involving metamaterials and a class of PT-symmetric quantum systems defined on wedge-shape contours in the complex plane. This provides a physical interpretation for the latter.

  2. Metamaterials, Point Interactions, Phase-Conjugation, and PT-Symmetry

    E-Print Network [OSTI]

    Mostafazadeh, Ali

    2015-01-01

    We express the boundary conditions for TE and TM waves at the interfaces of an infinite planar slab of homogeneous metamaterial as certain point interactions and use them to compute the transfer matrix of the system. This allows us to demonstrate the omnidirectional reflectionlessness of Veselago's slab for waves of arbitrary wavelength, reveal the translational and reflection symmetry of this slab, explore the laser threshold condition and coherent perfect absorption for active negative-index metamaterials, introduce a point interaction modeling phase-conjugation, determine the corresponding antilinear transfer matrix, and offer a simple proof of the equivalence of Veselago's slab with a pair of parallel phase-conjugating plates. We also study the connection between certain optical setups involving metamaterials and a class of PT-symmetric quantum systems defined on wedge-shape contours in the complex plane. This provides a physical interpretation for the latter.

  3. 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.

  4. TRAC-PD2 modeling of LOFT and PWR small cold-leg breaks

    SciTech Connect (OSTI)

    Knight, T.D.; Willcutt, G.J.E. Jr.; Lime, J.F.

    1981-01-01

    The Transient Reactor Analysis Code (TRAC) is being developed at the Los Alamos National Laboratory to provide advanced best-estimate predictions of postulated accidents in light-water reactors. TRAC-PD2, the latest publicly released version of the code, is currently being tested against small-break and other transients in experimental facilities; it is also being used to analyze postulated accidents in commercial power reactors. Calculated results for LOFT small-break experiments are compared to data, and the results from two small-break calculations for two different reactor systems are presented. It is concluded that TRAC-PD2 is useful for the analysis of cold-leg small-break accidents.

  5. Q-Value and Half-Lives for the Double-Beta-Decay Nuclide 110Pd

    E-Print Network [OSTI]

    D. Fink; J. Barea; D. Beck; K. Blaum; Ch. Böhm; Ch. Borgmann; M. Breitenfeldt; F. Herfurth; A. Herlert; J. Kotila; M. Kowalska; S. Kreim; D. Lunney; S. Naimi; M. Rosenbusch; S. Schwarz; L. Schweikhard; F. Simkovic; J. Stanja; K. Zuber

    2011-12-25

    The 110Pd double-beta decay Q-value was measured with the Penning-trap mass spectrometer ISOLTRAP to be Q = 2017.85(64) keV. This value shifted by 14 keV compared to the literature value and is 17 times more precise, resulting in new phase-space factors for the two-neutrino and neutrinoless decay modes. In addition a new set of the relevant matrix elements has been calculated. The expected half-life of the two-neutrino mode was reevaluated as 1.5(6) E20 yr. With its high natural abundance, the new results reveal 110Pd to be an excellent candidate for double-beta decay studies.

  6. Pd-Catalyzed O-Arylation of Ethyl Acetohydroximate: Synthesis of O-Arylhydroxylamines and Substituted Benzofurans

    E-Print Network [OSTI]

    Maimone, Thomas

    An efficient Pd catalyst for the O-arylation of ethyl acetohydroximate with aryl chlorides, bromides, and iodides has been developed. Ethyl acetohydroximate serves as an efficient hydroxylamine equivalent for C?O cross-coupling, ...

  7. FY14 Annual Report for NA-22 Project LA14-FY14-027-PD2Jb "Developing...

    Office of Scientific and Technical Information (OSTI)

    NA-22 Project LA14-FY14-027-PD2Jb "Developing Accurate Simulations of Correlated Data in Fission Events" Citation Details In-Document Search Title: FY14 Annual Report for NA-22...

  8. 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.

  9. 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.

  10. Synthesis of Methanol and Dimethyl Ether from Syngas over Pd/ZnO/Al2O3 Catalysts

    SciTech Connect (OSTI)

    Lebarbier, Vanessa MC; Dagle, Robert A.; Kovarik, Libor; Lizarazo Adarme, Jair A.; King, David L.; Palo, Daniel R.

    2012-10-01

    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 250°C to 380°C. High temperatures (e.g. 380°C) 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 220-280°C, suffers from a rapid deactivation when the reaction is conducted at high temperature (>320°C). On the contrary, a Pd/ZnO/Al2O3 catalyst was found to be highly stable for methanol and DME synthesis at 380°C. The Pd/ZnO/Al2O3 catalyst was thus further investigated for methanol and DME synthesis at P=34-69 bars, T= 250-380°C, 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 GHSV’s 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 Pdº 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.

  11. 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.

  12. Effects of Process Conditions on Properties of Electroplated Ni Thin Films for Microsystem Applications

    E-Print Network [OSTI]

    Fleck, Norman A.

    Effects of Process Conditions on Properties of Electroplated Ni Thin Films for Microsystem, Southampton SO17 1QJ, United Kingdom The properties of electroplated Ni thin films have been systematically, micromotors, and pneumatic actuators.3-11 Ni and NiFe are the electroplated metals most commonly used for MEMS

  13. TiNi shape memory alloy thin films for microactuator application

    E-Print Network [OSTI]

    Fu, Yongqing

    TiNi films were prepared by co-sputtering TiNi target and a separate Ti target. Crystalline structure and phase transformation behaviors of TiNi films were investigated. Results showed that TiNi films had fine grain size ...

  14. Perpendicular magnetic anisotropy in ion beam sputtered Co/Ni multilayers

    E-Print Network [OSTI]

    Rasin, Boris

    2009-01-01

    Co/Ni multilayers display perpendicular magnetic anisotropy and have applications in magnetic devices that could lead to a large increase in the density of magnetic storage. Co/Ni 10-(2 Å Co/ 8Å Ni) and 10-(2 Å Co/ 4 Å Ni) ...

  15. 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.

  16. Application of cluster-plus-glue-atom model to barrierless Cu–Ni–Ti and Cu–Ni–Ta 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 Cu–Ni–M (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 M–Ni is more negative than that of M–Cu.

  17. Effect of surface composition of Pt-Au alloy cathode catalyst on the performance of direct methanol fuel cells

    E-Print Network [OSTI]

    Zhao, Tianshou

    Effect of surface composition of Pt-Au alloy cathode catalyst on the performance of direct methanol 2010 Available online 12 June 2010 Keywords: Fuel cell Direct methanol fuel cell Catalyst Active Site Pt-Au alloy a b s t r a c t A pure Pt cathode catalyst in direct methanol fuel cells is not only

  18. DOI: 10.1002/cssc.201100525 CO Oxidation at the Perimeters of an FeO/Pt(111) Interface

    E-Print Network [OSTI]

    Li, Weixue

    reaction of the PEMFC, the utilized H2 fuel mostly comes from steam reforming of various hydrocarbons.[1 in the reforming products and en- vironment greatly affected low-temperature CO oxidation. For a Pt single crystal- The catalytic role of the PtÀFe cation ensemble presented at the perimeters of the FeO film supported on Pt(111

  19. Gorzkowski et al. 1 Changes in the Distribution of Interfaces in PMN-35 mol% PT as a Function of Time

    E-Print Network [OSTI]

    Rohrer, Gregory S.

    Gorzkowski et al. 1 Changes in the Distribution of Interfaces in PMN- 35 mol% PT as a Function-3890 Abstract The crystallographic distribution of surfaces surrounding grains in PMN- 35 mol% PT has been to solid- state growth methods demonstrated in Al2O3 11 and BaTiO3.12 Growth of PMN-35PT single crystals

  20. 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.

  1. 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.

  2. Hydrogen sorption characteristics of nanostructured Pd–10Rh 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.

  3. Hydrogen sorption characteristics of nanostructured Pd–10Rh processed by cryomilling

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

    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 thanmore »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.« less

  4. 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.

  5. 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.

  6. 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), UV–vis–NIR 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 N–Ni interaction as well as the proposition of electron transfer mechanisms from SWCNTs to NO via the Ni medium.

  7. $^{64}$Ni+$^{64}$Ni fusion reaction calculated with the density-constrained time-dependent Hartree-Fock formalism

    E-Print Network [OSTI]

    A. S. Umar; V. E. Oberacker

    2007-09-25

    We study fusion reactions of the $^{64}$Ni+$^{64}$Ni system using the density-constrained time-dependent Hartree-Fock (TDHF) formalism. In this formalism the fusion barriers are directly obtained from TDHF dynamics. In addition, we incorporate the entrance channel alignments of the slightly deformed (oblate) $^{64}$Ni nuclei due to dynamical Coulomb excitation. We show that alignment leads to a fusion barrier distribution and alters the naive picture for defining which energies are actually sub-barrier. We also show that core polarization effects could play a significant role in fusion cross section calculations.

  8. Electrodeposition of amorphous matrix Ni-W/Wp̳ composites

    E-Print Network [OSTI]

    Jenket, Donald R. (Donald Robert)

    2005-01-01

    An amorphous Ni-W alloy matrix was incorporated with W particulate through two types of electrodeposition. The plating bath for the electrodeposition contained nickel sulfate, sodium tungstate, sodium citrate, ammonium ...

  9. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    SciTech Connect (OSTI)

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India); Narayanan, V., E-mail: stephen-arum@hotmail.com; Stephen, A., E-mail: stephen-arum@hotmail.com [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai-600 025 (India)

    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.

  10. TiNi-based thin films for MEMS applications

    E-Print Network [OSTI]

    Fu, Yongqing

    In this paper, some critical issues and problems in the development of TiNi thin films were discussed, including preparation and characterization considerations, residual stress and adhesion, frequency improvement, fatigue ...

  11. Grain boundary relaxation strengthening of nanocrystalline Ni–W alloys

    E-Print Network [OSTI]

    Rupert, Timothy J.

    The hardening effect caused by the relaxation of nonequilibrium grain boundary structure has been explored in nanocrystalline Ni–W alloys. First, the kinetics of relaxation hardening are studied, showing that higher annealing ...

  12. Pd Diffusion on MgO(100): The Role of Defects and Small Cluster Mobilit.

    SciTech Connect (OSTI)

    Xu, Lijun; Henkelman, Graeme A.; Campbell, Charles T.; Jonsson, Hannes

    2006-02-09

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Density functional theory is used to explore the energy landscape of Pd atoms adsorbed on the terrace of MgO(10 0) and at oxygen vacancy sites. Saddle point finding methods reveal that small Pd clusters diffuse on the terrace in interesting ways. The monomer and dimer diffuse via single atom hops between oxygen sites with barriers of 0.34 eV and 0.43 eV respectively. The trimer and tetramer, however, form 3D clusters by overcoming a 2D–3D transition barrier of less than 60 meV. The trimer diffuses along the surface either by a walking or flipping motion, with comparable barriers of ca. 0.5 eV. The tetramer rolls along the terrace with a lower barrier of 0.42 eV. Soft rotational modes at the saddle point lead to an anomalously high prefactor of 1.3 · 1014 s!1 for tetramer diffusion. This prefactor is two order of magnitude higher than for monomer diffusion, making the tetramer the fastest diffusing species on the terrace at all temperatures for which diffusion is active (above 200 K). Neutral oxygen vacancy sites are found to bind Pd monomers with a 2.63 eV stronger binding energy than the terrace. A second Pd atom, however, binds to this trapped monomer with a smaller energy of 0.56 eV, so that dimers at defects dissociate on a time scale of milliseconds at room temperature. Larger clusters bind more strongly at defects. Trimers and tetramers dissociate from monomer-bound-defects at elevated temperatures of ca. 600 K. These species are also mobile on the terrace, suggesting they are important for the ripening observed at P600 K during Pd vapor deposition on MgO(100) by Haas et al. [G. Haas, A. Menck, H. Brune, J.V. Barth, J.A. Venables, K. Kern, Phys. Rev. B 61 (2000) 11105].

  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. 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.

  15. PT phase transition in a (2+1)-d relativistic system

    E-Print Network [OSTI]

    Mandal, Bhabani Prasad; Ali, Kawsar; Ghatak, Ananya

    2015-01-01

    We study a massless Dirac particle with PT symmetric non-Hermitian Rashba interaction in the background of Dirac oscillator potential to show the PT phase transition in a (2+1) dimensional relativistic system analytically. PT phase transition occurs when strength of the (i) imaginary Rashba interaction or (ii) transverse magnetic field exceed their respective critical values. Small mass gap in the spectrum, consistent with other approaches is generated as long as the system is in the unbroken phase. Relativistic Landau levels are constructed explicitly for such a system.

  16. PT phase transition in a (2+1)-d relativistic system

    E-Print Network [OSTI]

    Bhabani Prasad Mandal; Brijesh K. Mourya; Kawsar Ali; Ananya Ghatak

    2015-09-24

    We study a massless Dirac particle with PT symmetric non-Hermitian Rashba interaction in the background of Dirac oscillator potential to show the PT phase transition in a (2+1) dimensional relativistic system analytically. PT phase transition occurs when strength of the (i) imaginary Rashba interaction or (ii) transverse magnetic field exceed their respective critical values. Small mass gap in the spectrum, consistent with other approaches is generated as long as the system is in the unbroken phase. Relativistic Landau levels are constructed explicitly for such a system.

  17. Anomalous magnetic behavior in nanocomposite materials of reduced graphene oxide-Ni/NiFe{sub 2}O{sub 4}

    SciTech Connect (OSTI)

    Kollu, Pratap E-mail: anirmalagrace@vit.ac.in; Prathapani, Sateesh; Varaprasadarao, Eswara K.; Mallick, Sudhanshu; Bahadur, D. E-mail: anirmalagrace@vit.ac.in; Santosh, Chella; Grace, Andrews Nirmala E-mail: anirmalagrace@vit.ac.in

    2014-08-04

    Magnetic Reduced Graphene Oxide-Nickel/NiFe{sub 2}O{sub 4} (RGO-Ni/NF) nanocomposite has been synthesized by one pot solvothermal method. Respective phase formations and their purities in the composite are confirmed by High Resolution Transmission Electron Microscope and X Ray Diffraction, respectively. For the RGO-Ni/NF composite material finite-size effects lead to the anomalous magnetic behavior, which is corroborated in temperature and field dependent magnetization curves. Here, we are reporting the behavior of higher magnetization values for Zero Field Cooled condition to that of Field Cooled for the RGO-Ni/NF nanocomposite. Also, the observed negative and positive moments in Hysteresis loops at relatively smaller applied fields (100?Oe and 200?Oe) are explained on the basis of surface spin disorder.

  18. The Role of Partial Crystallinity on Hydrogen Permeation in Fe–Ni–B–Mo Based Metallic Glass Membranes

    SciTech Connect (OSTI)

    Brinkman, K.; Su, D.; Fox, E.; Korinko, P.; Missimer, D.; Adams, T.

    2011-08-15

    A potentially exciting material for membrane separations are metallic glass materials due to their low cost, high elastic toughness and resistance to hydrogen embrittlement as compared to crystalline Pd-based membrane systems. However, at elevated temperatures and extended operation times structural changes including partial crystallinity may appear in these amorphous metallic systems. This study reports on the investigation of time and temperature dependent crystalline phase formation in conjunction with in situ crystallization/hydrogen permeation experiments at elevated temperatures. At temperatures near 400 C a FeNi crystalline phase appears as 22 vol.% inside the host amorphous matrix and the resulting composite structure remains stable over 3 h at temperature. The hydrogen permeation at 400 C of the partially crystalline material is similar to the fully amorphous material near 5 x 10{sup -9} mol H{sub 2}/m s Pa{sup 1/2}, while ambient temperature electrochemical permeation at 25 C revealed an order of magnitude decrease in the permeation of partially crystalline materials due to differences in the amorphous versus crystalline phase activation energy for hydrogen permeation.

  19. Isotope correlations as a probe for freeze-out characterization: central 124Sn+64Ni, 112Sn+58Ni collisions

    E-Print Network [OSTI]

    E. Geraci; Reverse collaboration

    2003-10-15

    124Sn+64Ni and 112Sn+58Ni reactions at 35 AMeV incident energy were studied with the forward part of CHIMERA multi-detector. The most central collisions were selected by means of a multidimensional analysis. The characteristics of the source formed in the central collisions, as size, temperature and volume, were inspected. The measured isotopes of light fragments (3 <= Z <=8) were used to examine isotope yield ratios that provide information on the free neutron to proton densities.

  20. 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.

  1. Z-STEM Imaging of Chemical Ordering in FePt Magnetic Nanoparticles

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

    Z-STEM Imaging of Chemical Ordering in FePt Magnetic Nanoparticles J.E. Wittig, M.S. Wellons and C.M. Lukehart, Vanderbilt University J. Bentley and L.F. Allard, Oak Ridge National...

  2. Unconventional behavior of the Ce3Pt23Si11 ferromagnet C. Opagiste,1,

    E-Print Network [OSTI]

    Boyer, Edmond

    23Si11 is in equilibrium with the non-centrosymetric heavy fermion superconductor CePt3Si, when and presents a heavy fermion supercon- ducting state at Tc = 750 mK. Many studies on the superconductivity

  3. X-ray Photoelectron Spectroscopy and Kinetic Study: Pt-Group Metals and Bimetallic Surfaces 

    E-Print Network [OSTI]

    Gath, Kerrie K.

    2010-01-14

    Pt-group metals were some of the first metals to be studied as catalysts for industrial use. The goal of these studies was to ascertain a fundamental understanding of CO oxidation and acetylene cyclotrimerization reactions ...

  4. Thermally Stable Nanocatalyst for High Temperature Reactions: Pt-Mesoporous Silica Core-Shell Nanoparticles

    E-Print Network [OSTI]

    Park, J.Y.

    2010-01-01

    beam study of the catalytic oxidation of CO on a Pt(111)a model reaction. The catalytic oxidation of CO to CO 2 overA. Tuning of catalytic CO oxidation by changing composition

  5. pt5m - a 0.5m robotic telescope on La Palma

    E-Print Network [OSTI]

    Hardy, L K; Dhillon, V S; Littlefair, S P; Wilson, R W

    2015-01-01

    pt5m is a 0.5m robotic telescope located on the roof of the 4.2m William Herschel Telescope (WHT) building, at the Roque de los Muchachos Observatory, La Palma. Using a 5-position filter wheel and CCD detector, and bespoke control software, pt5m provides a high quality robotic observing facility. The telescope first began robotic observing in 2012, and is now contributing to transient follow-up and time-resolved astronomical studies. In this paper we present the scientific motivation behind pt5m, as well as the specifications and unique features of the facility. We also present an example of the science we have performed with pt5m, where we measure the radius of the transiting exoplanet WASP-33b. We find a planetary radius of 1.603 +/- 0.014 R(J).

  6. 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.

  7. Size Influence on the Oxygen Reduction Reaction Activity and Instability of Supported Pt Nanoparticles

    E-Print Network [OSTI]

    Sheng, Wenchao

    Size-dependent oxygen reduction reaction activity (ORR) and instability of Pt nanoparticles is of great importance in proton exchange membrane fuel cell applications. In this study, the size-dependence of ORR activity on ...

  8. Molecular Precursors-Induced Surface Reconstruction at Graphene/Pt(111) Interfaces

    E-Print Network [OSTI]

    Wang, Qian; Shi, Xingqiang

    2015-01-01

    Inspired by experimental observations of Pt(111) surfaces reconstruction at the Pt/graphene (Gr) interfaces with ordered vacancy networks in the outermost Pt layer, the mechanism of the surface reconstruction is investigated by van-der-Waals-corrected density functional theory in combination with particle-swarm optimization algorithm and ab initio atomistic thermodynamics. Our global structural search finds a more stable reconstructed (Rec) structure than that was reported before. With correction for vacancy formation energy, we demonstrate that the experimental observed surface reconstruction occurred at the earlier stages of graphene formation: 1) reconstruction occurred when C60 adsorption (before decomposition to form graphene) for C60 as a molecular precursor, or 2) reconstruction occurred when there were (partial) hydrogens retain in the adsorbed carbon structures for C2H4 and C60H30 as precursors. The reason can be attributed to that the energy gain, from the strengthened Pt-C bonding for C of C60 or f...

  9. Atomic Structure of (111) SrTiO3/Pt Interfaces

    E-Print Network [OSTI]

    Schmidt, Steffen; Klenov, Dmitri O.; Keane, Sean; Lu, Jiwei; Mates, Thomas; Stemmer, Susanne

    2006-01-01

    online) HRTEM of the Pt/STO interface recorded along 110 .the atom positions in the interface plane (the oxygen-onlydensity near the bottom interface [13] and studies by others

  10. The influence of nano-architectured CeOx supports in RhPd/CeO? 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 CeO? cubes and CeO? rods tailored towards the production of hydrogen. At 650-700 K the hydrogen yield follows the trend RhPd/CeO?-cubes > RhPd/CeO? -rods > RhPd/CeO?- 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/CeO?-cubes and RhPd/CeO? -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

  11. 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.

  12. Aligned and exchange-coupled L1{sub 0} (Fe,Co)Pt-based magnetic films

    SciTech Connect (OSTI)

    Liu, Y.; George, T. A.; Skomski, R.; Sellmyer, D. J. [Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States)

    2012-04-01

    Films of aligned L1{sub 0}-structure (Fe,Co)Pt with fcc Fe(Co,Pt) are synthesized by co-sputtering Fe, Co, and Pt on an (001) MgO substrate with in situ heating at 830 deg. C. The nanostructures and magnetic properties of the films are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID). The compositions of the samples (Fe,Co){sub x}Pt{sub 1-x} are designed to maintain an atomic Fe: Co ratio of 65: 35 while increasing the Fe,Co content in each successive sample. In samples with low Fe and Co concentration, the XRD patterns exhibit three strong peaks, namely L1{sub 0} (Fe,Co)Pt (001), L1{sub 0} (Fe,Co)Pt (002), and MgO (002). A fourth peak is observed in samples with high Fe and Co concentration and identified as fcc (002). The XRD patterns confirm the formation of L1{sub 0}-ordered (Fe,Co)Pt and its epitaxial growth on MgO. TEM shows that the (Fe,Co)Pt films form isolated magnetic grains of about 100 nm in diameter. Hysteresis-loop measurements show that the increase of the Fe,Co concentration from 57.3 to 68.3 at % enhances the saturation magnetization M{sub s} from 1245 emu/cm{sup 3} to 1416 emu/cm{sup 3}, and the coercivity decreases from 32 kOe to 8.9 kOe. The nominal maximum energy product per grain is 64 MGOe.

  13. 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.

  14. Synthesis of Pt nanoparticles on electrochemically reduced graphene oxide by potentiostatic and alternate current methods

    SciTech Connect (OSTI)

    Molina, J.; Fernández, J.; Río, A.I. del; Bonastre, J.; Cases, F., E-mail: fjcases@txp.upv.es

    2014-03-01

    Reduced graphene oxide (RGO) has been synthesized on Pt wires by means of a potentiodynamic method between + 0.6 V and ? 1.4 V for 20 scans. Cyclic voltammetry characterization of the coatings showed the typical capacitative behavior of graphene. Pt nanoparticles were synthesized on Pt–RGO electrodes by means of potentiostatic methods and a comparison between different synthesis potentials (? 0.16, 0, + 0.2 and + 0.4 V) for the same synthesis charge (mC·cm{sup ?2}) was established. The electrodes obtained were characterized in 0.5 M H{sub 2}SO{sub 4} solution to observe the characteristic oxidation and reduction processes of the Pt surface. A 0.5 M H{sub 2}SO{sub 4}/0.5 M CH{sub 3}OH solution was used to measure the catalytic properties of the deposits against methanol oxidation. The most appropriate potential to perform the synthesis was 0 V followed by ? 0.16 V and + 0.2 V. The morphology of the coatings varied depending on the potential applied as observed by scanning electron microscopy. Alternate current methods were also used to synthesize Pt nanoparticles and compare the results with the traditional potentiostatic method. Different frequencies were used: 0.1, 1, 10, 100, 1000 and 10 000 Hz. Alternate current synthesis is more efficient than traditional potentiostatic methods, obtaining more electroactive coatings with less effective synthesis time. - Highlights: • Reduced graphene oxide has been obtained by electrochemical reduction on Pt wires. • Pt nanoparticles have been obtained potentiostatically at different potentials. • Pt nanoparticles have been obtained by ac methods with different frequencies. • ac synthesis is a better synthesis method than potentiostatic synthesis.

  15. 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.

  16. Linear and Nonlinear PT-symmetric Oligomers: A Dynamical Systems Analysis

    E-Print Network [OSTI]

    M. Duanmu; K. Li; R. L. Horne; P. G. Kevrekidis; N. Whitaker

    2012-10-15

    In the present work we focus on the cases of two-site (dimer) and three-site (trimer) configurations, i.e. oligomers, respecting the parity-time (PT) symmetry, i.e., with a spatially odd gain-loss profile. We examine different types of solutions of such configurations with linear and nonlinear gain/loss profiles. Solutions beyond the linear PT-symmetry critical point as well as solutions with asymmetric linearization eigenvalues are found in both the nonlinear dimer and trimer. The latter feature is absent in linear PT-symmetric trimers, while both of them are absent in linear PT symmetric dimers. Furthermore, nonlinear gain/loss terms enable the existence of both symmetric and asymmetric solution profiles (and of bifurcations between them), while only symmetric solutions are present in the linear PT-symmetric dimers and trimers. The linear stability analysis around the obtained solutions is discussed and their dynamical evolution is explored by means of direct numerical simulations. Finally, a brief discussion is also given of recent progress in the context of PT-symmetric quadrimers.

  17. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

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

    Zhu, Jing; Zheng, Xin; Wang, Jie; Wu, Zexing; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/Cmore »and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.« less

  18. Epitaxial crystals of Bi?Pt?O? pyrochlore through the transformation of ?–Bi?O? fluorite

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

    Gutiérrez–Llorente, Araceli; Joress, Howie; Woll, Arthur; Holtz, Megan E.; Ward, Matthew J.; Sullivan, Matthew C.; Muller, David A.; Brock, Joel D.

    2015-03-01

    Bi?Pt?O? pyrochlore is thought to be one of the most promising oxide catalysts for application in fuel cell technology. Unfortunately, direct film growth of Bi?Pt?O? has not yet been achieved, owing to the difficulty of oxidizing platinum metal in the precursor material to Pt??. In this work, in order to induce oxidation of the platinum, we annealed pulsed laser deposited films consisting of epitaxial ?–Bi?O? and co-deposited, comparatively disordered platinum. We present synchrotron x-ray diffraction results that show the nonuniform annealed films contain the first epitaxial crystals of Bi?Pt?O?. We also visualized the pyrochlore structure by scanning transmission electron microscopy,more »and observed ordered cation vacancies in the epitaxial crystals formed in a bismuth-rich film but not in those formed in a platinum-rich film. The similarity between the ?–Bi?O? and Bi?Pt?O? structures appears to facilitate the pyrochlore formation. These results provide the only route to date for the formation of epitaxial Bi?Pt?O?.« less

  19. 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.

  20. 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.

  1. 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

  2. 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 Ingeniería y Ciencias Aplicadas, Universidad de los Andes, Monseñor 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 für Integrierte Naturwissenschaften - Physik, Universität 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.

  3. Nanoparticulate PdZn as a Novel Catalyst for ZnO Nanowire Growth

    E-Print Network [OSTI]

    2010-03-14

    at 500?C (see below). The prepared grids were dip coated with a methanol suspension of PdZn colloid (molar metal ratio 50:50) with a total metal concentration of 0.490 mg/ml. As a control sample, a silicon wafer was coated with particles under the same... at temperatures ranging from 560 to 820?C. An Ar/O2 mixture was used as the carrier gas. Subsequent analyses were carried out by both HRSEM and HRTEM along with EDS and SAED. An overview of the parameter combinations investigated is shown in Table 1. Selected...

  4. 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.

  5. Tidal Waves in $^{102}$Pd: A Rotating Condensate of Multiple $d$ bosons

    E-Print Network [OSTI]

    A. D. Ayangeakaa; U. Garg; M. A. Caprio; M. P. Carpenter; S. S. Ghugre; R. V. F. Janssens; F. G. Kondev; J. T. Matta; S. Mukhopadhyay; D. Patel; D. Seweryniak; J. Sun; S. Zhu; S. Frauendorf

    2013-02-02

    Low-lying collective excitations in even-even vibrational and transitional nuclei may be described semi-classically as quadrupole running waves on the surface of the nucleus ("tidal waves"), and the observed vibrational-rotational behavior can be thought of as resulting from a rotating condensate of interacting $d$ bosons. These concepts have been investigated by measuring lifetimes of the levels in the yrast band of the $^{102}$Pd nucleus with the Doppler Shift Attenuation Method. The extracted $B(E2)$ reduced transition probabilities for the yrast band display a monotonic increase with spin, in agreement with the interpretation based on rotation-induced condensation of aligned $d$ bosons.

  6. 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.

  7. Solving the stellar 62Ni problem with AMS

    E-Print Network [OSTI]

    I. Dillmann; T. Faestermann; G. Korschinek; J. Lachner; M. Maiti; M. Poutivtsev; G. Rugel; S. Walter; F. Käppeler; M. Erhard; A. R. Junghans; C. Nair; R. Schwengner; A. Wagner

    2009-07-01

    An accurate knowledge of the neutron capture cross sections of 62,63Ni is crucial since both isotopes take key positions which affect the whole reaction flow in the weak s process up to A=90. No experimental value for the 63Ni(n,gamma) cross section exists so far, and until recently the experimental values for 62Ni(n,gamma) at stellar temperatures (kT=30 keV) ranged between 12 and 37 mb. This latter discrepancy could now be solved by two activations with following AMS using the GAMS setup at the Munich tandem accelerator which are also in perfect agreement with a recent time-of-flight measurement. The resulting (preliminary) Maxwellian cross section at kT=30 keV was determined to be 30keV = 23.4 +/- 4.6 mb. Additionally, we have measured the 64Ni(gamma,n)63Ni cross section close to threshold. Photoactivations at 13.5 MeV, 11.4 MeV and 10.3 MeV were carried out with the ELBE accelerator at Forschungszentrum Dresden-Rossendorf. A first AMS measurement of the sample activated at 13.5 MeV revealed a cross section smaller by more than a factor of 2 compared to NON-SMOKER predictions.

  8. Modified Ni-Cu catalysts for ethanol steam reforming

    SciTech Connect (OSTI)

    Dan, M.; Mihet, M.; Almasan, V.; Borodi, G.; Katona, G.; Muresan, L.; Lazar, M. D.

    2013-11-13

    Three Ni-Cu catalysts, having different Cu content, supported on ?-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N{sub 2} adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

  9. 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.

  10. 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.

  11. Superior performance of Ni-W-Ce mixed-metal oxide catalysts for ethanol steam reforming: Synergistic effects of W- and Ni-dopants

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

    Rodriguez, Jose A.; Liu, Zongyuan; Xu, Wenqian; Yao, Siyu; Johnson-Peck, Aaron C.; Zhao, Fuzhen; Michorczyk, Piotr; Kubacka, Anna; Stach, Eric A.; Fernandez-Garica, Marcos; et al

    2014-11-26

    The ethanol steam reforming (ESR) reaction was studied over a series of Ni-W-Ce oxide catalysts. The structures of the catalysts were characterized using in-situ techniques including X-ray diffraction, Pair Distribution Function, X-ray absorption fine structure and transmission electron microscopy; while possible surface intermediates for the ESR reaction were investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy. In these materials, all the W and part of the Ni were incorporated into the CeO? lattice, with the remaining Ni forming highly dispersed nano NiO (more »The Ni-W-Ce systeme exhibited a much larger lattice strain than those seen for Ni-Ce and W-Ce. Synergistic effects between Ni and W inside ceria produced a substantial amount of defects and O vacancies that led to high catalytic activity, selectivity and stability (i.e. resistance to coke formation) during ethanol steam reforming.« less

  12. 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.

  13. Mitigation of Sulfur Poisoning of Ni/Zirconia SOFC Anodes by Antimony and Tin

    SciTech Connect (OSTI)

    Marina, Olga A.; Coyle, Christopher A.; Engelhard, Mark H.; Pederson, Larry R.

    2011-02-28

    Surface Ni/Sb and Ni/Sb alloys were found to efficiently minimize the negative effects of sulfur on the performance of Ni/zirconia anode-supported solid oxide fuel cells (SOFC). Prior to operating on fuel gas containing low concentrations of H2S, the nickel/zirconia anodes were briefly exposed to antimony or tin vapor, which only slightly affected the SOFC performance. During the subsequent exposures to 1 and 5 ppm H2S, increases in anodic polarization losses were minimal compared to those observed for the standard nickel/zirconia anodes. Post-test XPS analyses showed that Sb and Sn tended to segregate to the surface of Ni particles, and further confirmed a significant reduction of adsorbed sulfur on the Ni surface in Ni/Sn and Ni/Sb samples compared to the Ni. The effect may be the result of weaker sulfur adsorption on bimetallic surfaces, adsorption site competition between sulfur and Sb or Sn on Ni, or other factors. The use of dilute binary alloys of Ni-Sb or Ni-Sn in the place of Ni, or brief exposure to Sb or Sn vapor, may be effective means to counteract the effects of sulfur poisoning in SOFC anodes and Ni catalysts. Other advantages, including suppression of coking or tailoring the anode composition for the internal reforming, are also expected.

  14. Sample dependence of giant magnetocaloric effect in a cluster-glass system Ho{sub 5}Pd{sub 2}

    SciTech Connect (OSTI)

    Toyoizumi, Saori Tamaki, Akira; Kitazawa, Hideaki; Mamiya, Hiroaki; Terada, Noriki; Tamura, Ryo; Dönni, Andreas; Kawamura, Yukihiko; Morita, Kengo

    2015-05-07

    In order to investigate the effect of vacancy on the magnetocaloric effect in Ho{sub 5}Pd{sub 2}, we have carried out X-ray diffraction, magnetization, and specific heat measurements in the rare-earth intermetallic compound Ho{sub 5+x}Pd{sub 2}(?0.4???x???0.4). The maximum magnetic entropy change ??S{sub m}{sup max}, the maximum adiabatic temperature change ?T{sub ad}{sup max}, and the relative cooling power of Ho{sub 5+x}Pd{sub 2} take large values at x?=?0?0.4 for the field change of 5?T. The paramagnetic Curie temperature ?{sub p} increases with an increase of x. This fact suggests that the enhancement of ferromagnetic coupling among the correlated spins leads to the increase of magnetocaloric effect.

  15. Bimetallic Fe-Ni Oxygen Carriers for Chemical Looping Combustion

    SciTech Connect (OSTI)

    Bhavsar, Saurabh; Veser, Goetz

    2013-11-06

    The relative abundance, low cost, and low toxicity of iron make Fe-based oxygen carriers of great interest for chemical looping combustion (CLC), an emerging technology for clean and efficient combustion of fossil and renewable fuels. However, Fe also shows much lower reactivity than other metals (such as Ni and Cu). Here, we demonstrate strong improvement of Fe-based carriers by alloying the metal phase with Ni. Through a combination of carrier synthesis and characterization with thermogravimetric and fixed-bed reactor studies, we demonstrate that the addition of Ni results in a significant enhancement in activity as well as an increase in selectivity for total oxidation. Furthermore, comparing alumina and ceria as support materials highlights the fact that reducible supports can result in a strong increase in oxygen carrier utilization.

  16. Ag-Pd-Cu alloy inserted transparent indium tin oxide electrodes for organic solar cells

    SciTech Connect (OSTI)

    Kim, Hyo-Joong; Seo, Ki-Won; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr [Department of Advanced Materials Engineering for Information and Electronics, Kyung-Hee University, 1 Seocheon-dong, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Noh, Yong-Jin; Na, Seok-In [Graduate School of Flexible and Printable Electronics, Chonbuk National University, 664-14, Deokjin-dong, Jeonju-si, Jeollabuk-do 561-756 (Korea, Republic of)

    2014-09-01

    The authors report on the characteristics of Ag-Pd-Cu (APC) alloy-inserted indium tin oxide (ITO) films sputtered on a glass substrate at room temperature for application as transparent anodes in organic solar cells (OSCs). The effect of the APC interlayer thickness on the electrical, optical, structural, and morphological properties of the ITO/APC/ITO multilayer were investigated and compared to those of ITO/Ag/ITO multilayer electrodes. At the optimized APC thickness of 8?nm, the ITO/APC/ITO multilayer exhibited a resistivity of 8.55?×?10{sup ?5} ? cm, an optical transmittance of 82.63%, and a figure-of-merit value of 13.54?×?10{sup ?3} ?{sup ?1}, comparable to those of the ITO/Ag/ITO multilayer. Unlike the ITO/Ag/ITO multilayer, agglomeration of the metal interlayer was effectively relieved with APC interlayer due to existence of Pd and Cu elements in the thin region of the APC interlayer. The OSCs fabricated on the ITO/APC/ITO multilayer showed higher power conversion efficiency than that of OSCs prepared on the ITO/Ag/ITO multilayer below 10?nm due to the flatness of the APC layer. The improved performance of the OSCs with ITO/APC/ITO multilayer electrodes indicates that the APC alloy interlayer prevents the agglomeration of the Ag-based metal interlayer and can decrease the thickness of the metal interlayer in the oxide-metal-oxide multilayer of high-performance OSCs.

  17. EFFECT OF IMPURITIES ON THE PERFORMANCE OF A Pd-Ag DIFFUSER

    SciTech Connect (OSTI)

    Morgan, G.

    2010-12-16

    A commercially fabricated diffuser purchased from Johnson-Matthey, Inc. was evaluated for performance characterization testing at the Savannah River National Laboratory (SRNL). Different impurities are often present in the feed streams of the process diffusers, but the effect of these impurities on the diffuser performance is currently unknown. Various impurities were introduced into the feed stream of the diffuser at various levels ranging from 0.5% to 10% of the total flow in order to determine the effect that these impurities have on the permeation of hydrogen through the palladium-silver membrane. The introduction of various impurities into the feed stream of the diffuser had a minimal effect on the overall permeation of hydrogen through the Pd-Ag membrane. Of the four impurities introduced into the feed stream, carbon monoxide (CO) was the only impurity that showed any evidence of causing a reduction in the amount of hydrogen permeating through the Pd-Ag membrane. The hydrogen permeation returned to its baseline level after the CO was removed from the feed stream. There were no lasting effects of the CO exposure on the ability of the membrane to effectively separate hydrogen from the non-hydrogen species in the gas stream under the conditions tested.

  18. Absolute Drell-Yan Dimuon Cross Sections in 800 GeV/c pp and pd Collisions

    E-Print Network [OSTI]

    FNAL E866/NuSea Collaboration; :; J. C. Webb; T. C. Awes; M. L. Brooks; C. N. Brown; J. D. Bush; T. A. Carey; T. H. Chang; W. E. Cooper; C. A. Gagliardi; G. T. Garvey; D. F. Geesaman; E. A. Hawker; X. C. He; L. D. Isenhower; D. M. Kaplan; S. B. Kaufman; D. D. Koetke; D. M. Lee; W. M. Lee; M. J. Leitch; N. Makins; P. L. McGaughey; J. M. Moss; B. A. Mueller; P. M. Nord; V. Papavassiliou; B. K. Park; J. C. Peng; G. Petitt; P. E. Reimer; M. E. Sadler; W. E. Sondheim; P. W. Stankus; T. N. Thompson; R. S. Towell; R. E. Tribble; M. A. Vasiliev; J. L. Willis; D. K. Wise; G. R. Young

    2003-02-14

    The Fermilab E866/NuSea Collaboration has measured the Drell-Yan dimuon cross sections in 800 GeV/$c$ $pp$ and $pd$ collisions. This represents the first measurement of the Drell-Yan cross section in $pp$ collisions over a broad kinematic region and the most extensive study to date of the Drell-Yan cross section in $pd$ collisions. The results indicate that recent global parton distribution fits provide a good description of the light antiquark sea in the nucleon over the Bjorken-$x$ range $0.03 \\lesssim x < 0.15$, but overestimate the valence quark distributions as $x \\to 1$.

  19. Healing of graphene on single crystalline Ni(111) films

    SciTech Connect (OSTI)

    Zeller, Patrick; Wintterlin, Joost; Speck, Florian; Ostler, Markus; Weinl, Michael; Schreck, Matthias; Seyller, Thomas

    2014-11-10

    The annealing of graphene layers grown on 150?nm thick single crystal Ni(111) films was investigated in situ by low energy electron microscopy and photoemission electron microscopy. After growth, by means of chemical vapor deposition of ethylene, the graphene layers consist of several domains showing different orientations with respect to the underlying Ni surface and also of small bilayer areas. It is shown that, in a controlled process, the rotated domains can be transformed into lattice-aligned graphene, and the bilayer areas can be selectively dissolved, so that exclusively the aligned monolayer graphene is obtained. The ordering mechanism involves transport of C atoms across the surface and solution in the bulk.

  20. Synthesis, electrochemistry and First Principles Calculation studies of layered Li-Ni-Ti-O compounds

    E-Print Network [OSTI]

    Kang, Kisuk

    New layered cathode materials, Li?.?Ni?.??Ti?.??O?, were synthesized by means of ion-exchange from Na?.?Ni?.??Ti?.??O?. The degree of cation disordering in the material depends critically on the synthesis conditions. Longer ...

  1. Effect of Aging Heat Treatments on Ni52Ti48 Shape Memory Alloy 

    E-Print Network [OSTI]

    Akin, Erhan

    2011-10-21

    Ni-rich NiTi shape memory alloys (SMAs) are capable of attaining a wide range of transformation temperatures depending on the heat treatment conditions and superior thermo-mechanical cycling stability, which are desired for repeated solid...

  2. Mechanism(s) of Ni Sorption on Al-Hydroxy-Interlayered Vermiculite Using Time-Resolved EXAFS

    E-Print Network [OSTI]

    Sparks, Donald L.

    Mechanism(s) of Ni Sorption on Al-Hydroxy-Interlayered Vermiculite Using Time-Resolved EXAFS D. R sorbed and the mechanism of Ni sorption. #12;

  3. Aging is the primary risk factor for the majority of neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD). There are almost 40 million

    E-Print Network [OSTI]

    Liu, Taosheng

    Alzheimer's disease (AD) and Parkinson's disease (PD). There are almost 40 million people aged 65 and genetics that promote healthy aging will decrease the incidence of these diseases in the general population James Parkinson first described the clinical symptoms of Parkinson's disease (PD) in his 1817 monograph

  4. Conversion of CH4 into H2 at 300 C using Pd/MnO2 catalyst made with an effect of water oxidation

    SciTech Connect (OSTI)

    Koyanaka, Hideki; Takeuchi, K; Kolesnikov, Alexander I

    2014-01-01

    A novel electricity-free deposition of palladium on the surface of manganese dioxide, which has a crystal structure of ramsdellite, was studied. Using the Pd deposition, a nano-particle of Pd/MnO2 was prepared, and it was used for a catalytic performance for reforming methane into hydrogen at 300 C.

  5. Superior performance of Ni-W-Ce mixed-metal oxide catalysts for ethanol steam reforming: Synergistic effects of W- and Ni-dopants

    SciTech Connect (OSTI)

    Rodriguez, Jose A.; Liu, Zongyuan; Xu, Wenqian; Yao, Siyu; Johnson-Peck, Aaron C.; Zhao, Fuzhen; Michorczyk, Piotr; Kubacka, Anna; Stach, Eric A.; Fernandez-Garica, Marcos; Senanayake, Sanjaya D.

    2014-11-26

    The ethanol steam reforming (ESR) reaction was studied over a series of Ni-W-Ce oxide catalysts. The structures of the catalysts were characterized using in-situ techniques including X-ray diffraction, Pair Distribution Function, X-ray absorption fine structure and transmission electron microscopy; while possible surface intermediates for the ESR reaction were investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy. In these materials, all the W and part of the Ni were incorporated into the CeO? lattice, with the remaining Ni forming highly dispersed nano NiO (< 2 nm) outside the Ni-W-Ce oxide structure. The nano NiO was reduced to Ni under ESR conditions. The Ni-W-Ce systeme exhibited a much larger lattice strain than those seen for Ni-Ce and W-Ce. Synergistic effects between Ni and W inside ceria produced a substantial amount of defects and O vacancies that led to high catalytic activity, selectivity and stability (i.e. resistance to coke formation) during ethanol steam reforming.

  6. Superior performance of Ni-W-Ce mixed-metal oxide catalysts for ethanol steam reforming: Synergistic effects of W- and Ni-dopants

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

    Rodriguez, Jose A. [Brookhaven National Lab. (BNL), Upton, NY (United States); State Univ. of New York Stony Brook, Stony Brook, NY (United States); Liu, Zongyuan [Brookhaven National Lab. (BNL), Upton, NY (United States); State Univ. of New York Stony Brook, Stony Brook, NY (United States); Xu, Wenqian [Brookhaven National Lab. (BNL), Upton, NY (United States); Yao, Siyu [Brookhaven National Lab. (BNL), Upton, NY (United States); Johnson-Peck, Aaron C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhao, Fuzhen [Brookhaven National Lab. (BNL), Upton, NY (United States); Michorczyk, Piotr [Inst. de Catalisis y Petroleoquimica, Madrid (Spain); Kubacka, Anna [Inst. de Catalisis y Petroleoquimica, Madrid (Spain); Stach, Eric A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fernandez-Garica, Marcos [State Univ. of New York Stony Brook, Stony Brook, NY (United States); Senanayake, Sanjaya D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-01-01

    The ethanol steam reforming (ESR) reaction was studied over a series of Ni-W-Ce oxide catalysts. The structures of the catalysts were characterized using in-situ techniques including X-ray diffraction, Pair Distribution Function, X-ray absorption fine structure and transmission electron microscopy; while possible surface intermediates for the ESR reaction were investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy. In these materials, all the W and part of the Ni were incorporated into the CeO? lattice, with the remaining Ni forming highly dispersed nano NiO (< 2 nm) outside the Ni-W-Ce oxide structure. The nano NiO was reduced to Ni under ESR conditions. The Ni-W-Ce systeme exhibited a much larger lattice strain than those seen for Ni-Ce and W-Ce. Synergistic effects between Ni and W inside ceria produced a substantial amount of defects and O vacancies that led to high catalytic activity, selectivity and stability (i.e. resistance to coke formation) during ethanol steam reforming.

  7. XES Nanoprobe for Hard X-Ray Region: Mitigating Degradation in Ni-ZEBRA Batteries Research Team: Mark Bowden, Kyle Alvine, Nancy Hess, Guosheng Li, Tamas Varga

    E-Print Network [OSTI]

    XES Nanoprobe for Hard X-Ray Region: Mitigating Degradation in Ni-ZEBRA Batteries Research Team scientific understanding of link between Ni-NiCl2 ZEBRA battery cycle degradation and FeS additive Chemical battery performance by poisoning Ni surfaces ­ optimizing Ni/NiCl2 distributions and conductive pathways

  8. Investigation of high p$_{t}$ events in Nucleus-Nucleus collisions using the Hijing event generator

    E-Print Network [OSTI]

    Natasha Sharma; Madan M. Aggarwal

    2009-10-29

    In recent years lot of interest has been observed in the nucleus-nucleus collisions at RHIC energies in phenomena related to high $p_{t}$ physics \\cite{ref1}. The suppression of high $p_{t}$ particles and disappearance of back-to-back jets compared to the scaling with number of binary nucleon-nucleon collisions indicates that a nearly perfect liquid is produced in these collisions. Results on self shadowing of high $p_{t}$ events are presented using hadron multiplicity associated to high $p_{t}$ and unbiased events in nucleus-nucleus collisions \\cite{ref2} obtained from the hijing event generator.

  9. Shape memory response of ni2mnga and nimncoin magnetic shape memory alloys under compression 

    E-Print Network [OSTI]

    Brewer, Andrew Lee

    2009-05-15

    In this study, the shape memory response of Ni2MnGa and NiMnCoIn magnetic shape memory alloys was observed under compressive stresses. Ni2MnGa is a magnetic shape memory alloy (MSMA) that has been shown to exhibit fully ...

  10. CO2 hydrogenation to formic acid on Ni(110) Guowen Peng a

    E-Print Network [OSTI]

    Sibener, Steven

    CO2 hydrogenation to formic acid on Ni(110) Guowen Peng a , S.J. Sibener b , George C. Schatz c of subsurface H for hydrogenating carbon dioxide (CO2) on Ni(110). The energetics of surface and subsurface H reacting with surface CO2 to form for- mate, carboxyl, and formic acid on Ni(110) is systematically studied

  11. Investigation of Ni Sorption on Pyrophyllite: An XAFS Study

    E-Print Network [OSTI]

    Sparks, Donald L.

    , * , G E R A L D I N E M . L A M B L E , A N D D O N A L D L . S P A R K S Department of Plant and SoilInvestigation of Ni Sorption on Pyrophyllite: An XAFS Study A N D R E M . S C H E I D E G G E R

  12. Semantic Sensor Net: An Extensible Framework Lionel M. Ni1

    E-Print Network [OSTI]

    Liu, Yunhao

    (MEMS) have led to the wide deployment of large-scale wireless sensor networks (WSN), which promisesSemantic Sensor Net: An Extensible Framework Lionel M. Ni1 , Yanmin Zhu1 , Jian Ma1 , Minglu Li2-ml@cs.sjtu.edu.cn Abstract. Existing approaches for sensor networks suffer from a number of critical drawbacks. First

  13. High strain rate deformation of NiAl

    SciTech Connect (OSTI)

    Maloy, S.A.; Gray, G.T. III; Darolia, R.

    1994-07-01

    NiAl is a potential high temperature structural material. Applications for which NiAl is being considered (such as rotating components in jet engines) requires knowledge of mechanical properties over a wide range of strain rates. Single crystal NiAl (stoichiometric and Ni 49.75Al 0.25Fe) has been deformed in compression along [100] at strain rates of 0.001, 0.1/s and 2000/s and temperatures of 76,298 and 773K. <111> slip was observed after 76K testing at a strain rate of 0.001/s and 298K testing at a strain rate of 2000/s. Kinking was observed after deformation at 298K and a strain rate of 0.001/s and sometimes at 298 K and a strain rate of 0.1/s. Strain hardening rates of 8200 and 4000 MPa were observed after 773 and 298K testing respectively, at a strain rate of 2000/s. Results are discussed in reference to resulting dislocation substructure.

  14. 90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer spin valve component investigated by polarized neutron reflectometry

    SciTech Connect (OSTI)

    Callori, S. J., E-mail: sara.callori@ansto.gov.au; Bertinshaw, J. [School of Physics, The University of New South Wales, Sydney, New South Wales 2052 (Australia); Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Cortie, D. L. [The Institute for Superconducting and Electronic Materials, The University of Wollongong, Wollongong, New South Wales 2522 (Australia); Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Cai, J. W., E-mail: jwcai@aphy.iphy.ac.cn; Zhu, T. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Le Brun, A. P. [Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Klose, F. [Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, New South Wales 2234 (Australia); Department of Physics and Materials Science, City University of Hong Kong (Hong Kong)

    2014-07-21

    We have observed 90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer system using polarized neutron reflectometry. Magnetometry results show magnetic switching for both the biased and free NiFe layers, the latter of which reverses at low applied fields. As these measurements are only capable of providing information about the total magnetization within a sample, polarized neutron reflectometry was used to investigate the reversal behavior of the NiFe layers individually. Both the non-spin-flip and spin-flip neutron reflectometry signals were tracked around the free NiFe layer hysteresis loop and were used to detail the evolution of the magnetization during reversal. At low magnetic fields near the free NiFe coercive field, a large spin-flip signal was observed, indicating magnetization aligned perpendicular to both the applied field and pinned layer.

  15. Contribution of individual interfaces in the MgO/Co/Pd trilayer to perpendicular magnetic anisotropy upon annealing

    SciTech Connect (OSTI)

    Kim, Minseok; Kim, Sanghoon; Ko, Jungho; Hong, Jongill

    2015-03-09

    The contribution of each interface of the MgO/Co/Pd trilayer to the perpendicular magnetic anisotropy (PMA) was studied by changing chemical and crystalline structures through annealing. We found that volumetric anisotropy in the MgO/Co/Pd trilayer was significantly increased due to enhanced magnetoelastic anisotropy caused by stress built up most likely at the MgO/Co interface during annealing. When the trilayer was annealed at 400?°C, the alloy formation at the Co/Pd interface additionally increased the volumetric anisotropy. Our x-ray magnetic circular dichroism study supported that those structural modifications led to an increase in the orbital moment through spin-orbit coupling (SOC) along the film normal two times larger than that of the as-deposited trilayer, thereby enhancing PMA greatly. Our experimental results prove that the Co/Pd interface, rather than the MgO/Co interface, plays an essential role in inducing strong PMA in the trilayer. The precise investigation of annealing effect on both volumetric and interfacial anisotropies can provide a methodological solution to improve the SOC of the trilayer that can serve as the core unit of spintronic devices.

  16. Palladium Nanoparticles by Electrospinning from Poly(acrylonitrile-co-acrylic acid)-PdCl2 Solutions. Relations between

    E-Print Network [OSTI]

    Yanikoglu, Berrin

    Palladium Nanoparticles by Electrospinning from Poly(acrylonitrile-co-acrylic acid)-PdCl2 Solutions agglomeration can be elimi- nated. Electrospinning is a fiber fabrication technique that produces continuous, and membrane technology. The present work combines two methods of electrospinning and reduction of metal salts

  17. Determination of redox reaction rates and orders by in situ liquid cell electron microscopy of Pd and Au solution growth

    SciTech Connect (OSTI)

    Sutter, Eli A.; Sutter, Peter W.

    2014-11-19

    In-situ liquid cell transmission and scanning transmission electron microscopy (TEM/STEM) experiments are important as they provide direct insight into processes in liquids, such as solution growth of nanoparticles among others. In liquid cell TEM/STEM redox reaction experiments the hydrated electrons e?aq created by the electron beam are responsible for the reduction of metal-ion complexes. Here we investigate the rate equation of redox reactions involving reduction by e?aq generated by the electron beam during in-situ liquid TEM/STEM. Specifically we consider the growth of Pd on Au seeds in aqueous solutions containing Pd-chloro complexes. From the quantification of the rate of Pd deposition at different electron beam currents and as a function of distance from a stationary, nanometer-sized exciting beam, we determine that the reaction is first order with respect to the concentration of hydrated electrons, [e?aq]. In addition, by comparing Pd- and Au-deposition, we further demonstrate that measurements of the local deposition rate on nanoparticles in the solution via real-time imaging can be used to measure not only [e?aq] but also the rate of reduction of a metal-ion complex to zero-valent metal atoms in solution.

  18. Probing the nuclides {sup 102}Pd, {sup 106}Cd, and {sup 144}Sm for resonant neutrinoless double-electron capture

    SciTech Connect (OSTI)

    Goncharov, M.; Blaum, K.; Eliseev, S.; Block, M.; Herfurth, F.; Minaya Ramirez, E.; Droese, C.; Schweikhard, L.; Novikov, Yu. N.; Zuber, K.

    2011-08-15

    The Q values for double-electron capture in {sup 102}Pd, {sup 106}Cd, and {sup 144}Sm have been measured by Penning-trap mass spectrometry. The results exclude at present all three nuclides from the list of suitable candidates for a search for resonant neutrinoless double-electron capture.

  19. Synthesis and study of ligands for Pd-catalyzed C-O and C-N coupling

    E-Print Network [OSTI]

    Davis, Nicole R. (Nicole Rose)

    2009-01-01

    A new ligand, AdBrettPhos, was synthesized and its use, along with tBuBrettPhos, in C-O coupling reactions at low temperatures was investigated. Using Pd catalysts containing these ligands, electron-neutral aryl bromides ...

  20. Determination of the structure of disordered overlayers of ethylene on clean and hydrogen-covered Pd111

    E-Print Network [OSTI]

    Saldin, Dilano

    Determination of the structure of disordered overlayers of ethylene on clean and hydrogen. The structure of a disordered overlayer of ethylene on hydrogen-covered Pdð111� at 80 K is also measured using, morphology, roughness, and topography; Chemisorption; Palladium; Alkenes 1. Introduction The surface

  1. 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.

  2. 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.

  3. 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.

  4. 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. (ANU)

    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.

  5. Controlled Growth of Metal Phthalocyanine on Deactivated Si Surfaces by Selective p-d Orbital Coupling

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

    Wagner, Sean R.; Huang, Bing; Park, Changwon; Feng, Jiagui; Yoon, Mina; Zhang, Pengpeng

    2015-08-26

    Poor control of the interactions that govern organic molecular growth continues to hinder the prospect of organic electronic nano- architectures. Particularly, a selective mechanism for tuning the molecule-substrate interaction has been a long sought after goal towards tailored molecular growth. Here, combining scanning tun- neling microscopy and density functional theory we show that by controlling the strength of orbital hybridization between phthalo- cyanine molecules and the deactivated Si surface via the selective p-d orbital coupling, we can tune the molecular ordering and molecular orientation at the hetero-interface. This mechanism offers a novel approach to balance the critical interactions, leading tomore »controlled long-ranged ordered molecular growth that can be incorporated into modern electronics.« less

  6. Surface Segregation in a PdCu Alloy Hydrogen Separation Membrane

    SciTech Connect (OSTI)

    Miller, J.B.; Matranga, C.S.; Gellman, A.J.

    2007-06-01

    Separation of hydrogen from mixed gas streams is an important step for hydrogen generation technologies, including hydrocarbon reforming and coal/biomass gasification. Dense palladium-based membranes have received significant attention for this application because of palladium’s ability to dissociatively adsorb molecular hydrogen at its surface for subsequent transport of hydrogen atoms through its bulk. Alloying palladium with minor components, like copper, has been shown to improve both the membrane’s structural characteristics and resistance to poisoning of its catalytic surface [1]. Surface segregation—a composition difference between the bulk material and its surface—is common in alloys and can affect important surface processes. Rational design of alloy membranes requires that surface segregation be understood, and possibly controlled. In this work, we examine surface segregation in a polycrystalline Pd70Cu30 hydrogen separation membrane as a function of thermal treatment and adsorption of hydrogen sulfide.

  7. 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.

  8. Structure, thermodynamic, and magnetic properties of Ln[sub 4]PdO[sub 7] with Ln = La, Nd, Sm, Eu, and Gd

    SciTech Connect (OSTI)

    Andersson, M.; Grins, J.; Nygren, M. (Stockholm Univ. (Sweden))

    1999-09-01

    The structure of Nd[sub 4]PdO[sub 7] has been determined and refined using the Rietveld method and combined CuK[alpha][sub 1] X-ray and neutron powder data in space group P[bar 1] with unit cell a = 15.972(2), b = 7.1927(7), c = 6.9160(6) [angstrom], [alpha] = 96.299(4), [beta] = 131.643(3), [gamma] = 121.438(3)[degree], V = 353.83(6) [angstrom][sup 3] and Z = 2, to R[sub F] = 2.0% (neutron data) and R[sub F] = 6.2% (X-ray data). The structure is closely related to the monoclinic La[sub 4]PdO[sub 7] structure and exhibits Nd atoms coordinated by seven O atoms and Pd atoms coordinated by a square of O atoms. Isolated chains of trans-corner-sharing PdO[sub 4] squares are straight in the La[sub 4]PdO[sub 7] structure and staggered in the Nd[sub 4]PdO[sub 7] structure. Electron and X-ray powder diffraction data show that Ln[sub 4]PdO[sub 7] with Ln = Sm, Eu, and Gd is isostructural with Nd[sub 4]PdO[sub 7]. The enthalpies of dissolution of Ln[sub 4]PdO[sub 7] (Ln = La, Nd) in 1.000 M HCl have been measured with an in-house built calorimeter, and from these values the enthalpies of formation for the compounds have been calculated. The decomposition temperatures of Ln[sub 4]PdO[sub 7] with Ln = La and Nd in oxygen have been determined by thermogravimetric measurements and found to decrease from 1645 [+-] 10 K for La[sub 4]PdO[sub 7] to 1540 [+-] 10 K for Nd[sub 4]PdO[sub 7]. Using these data, an Ellingham diagram has been constructed assuming temperature-independent [Delta]H[sub f][degree] and [Delta]S[sub f][degree]. The magnetic susceptibilities of Ln[sub 4]PdO[sub 7] with Ln = La, Nd, Sm, Eu, Gd, recorded in the temperature range 10--320 K, were found to be in agreement with the expected ones for noninteracting Ln[sup 3+] ions.

  9. Low-temperature magnetization in Ni-rich gamma-Ni100-x-yFexVy alloys 

    E-Print Network [OSTI]

    Chakraborty, S.; Mukherjee, GD; Rathnayaka, KDD; Naugle, Donald G.; Majumdar, AK.

    2000-01-01

    Detailed studies of the temperature dependence of the spontaneous magnetization have been made in eight different compositions of gamma-Ni100-x-yFexVy (4 less than or equal to x less than or equal to 17; 2 less than or equal to y less than or equal...

  10. Probing antiferromagnetism in NiMn/Ni/(Co)/Cu3Au(001) single-crystalline epitaxial thin films

    E-Print Network [OSTI]

    Kuch, Wolfgang

    hexagonal-close- packed and composition-modulated atomic layer stacking Appl. Phys. Lett. 102, 012407 (2013-of-plane (OoP) as well as in-plane (IP) magnetized Ni films, the latter stabilized by Co under-layer deposition) Electron molecular beam epitaxy: Layer-by-layer growth of complex oxides via pulsed electron

  11. First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

    SciTech Connect (OSTI)

    Saadi, Souheil

    2011-03-01

    We investigate the structure and surface composition of the {gamma}{prime}-Ni{sub 3}Al(111) and {beta}-NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel-aluminum alloys are protected by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni{sub 3}Al and NiAl surfaces, the conditions under which CO and OH adsorption is to be expected and under which it is inhibited, are mapped out. Because CO and OH are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the CO and OH coverages depend on the steam to carbon ratio (S/C) in the gas and thereby provide a ranking of the carbon limits on the different surface phases.

  12. STRUCTURAL DETERMINATION OF MOLECULAR OVERLAYER SYSTEMS WITH NORMAL PHOTOELECTRON DIFFRACTION: c(2x2)CO-Ni(001) AND (/3 x /3)R30| Co-Ni(111)

    E-Print Network [OSTI]

    Kevan, S.D.

    2012-01-01

    electron diffraction (LEED), for subsequent, quantitativeadsorption system and because LEED structure analysis has° CO-Ni(lll) system, for which no LEED data presently exist.

  13. [1] P.T. de Zeeuw and C. Hunter. Astrophysical Journal, 356:365, 1990. [2] C. Hunter and P.T. de Zeeuw. Astrophysical Journal, 389:79, 1992.

    E-Print Network [OSTI]

    Terzi, Bal?a

    REFERENCES [1] P.T. de Zeeuw and C. Hunter. Astrophysical Journal, 356:365, 1990. [2] C. Hunter and P.T. de Zeeuw. Astrophysical Journal, 389:79, 1992. [3] F. Bertola and M. Capacciolli. Astrophysical Journal, 200:439, 1975. [4] J. Binney. Comments Astrophysics, 8:27, 1978. [5] M. Schwarzschild

  14. Supersymmetric analysis of the Dirac-Weyl operator within PT symmetry

    SciTech Connect (OSTI)

    Ye?ilta?, Özlem

    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, 2580–2583 (2012)] to the both PT symmetric and real Scarf II partner potentials is given using the position dependent Fermi velocity.

  15. 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

  16. 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.

  17. {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.

  18. 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 original studies of anion exchange ionomers as entrapment materials for rotating disc electrode (RDE) studies in alkaline media. Their significance is linked to the development of membrane electrode assemblies (MEAs) with the same ionomer for a KOH-free alkaline fuel cell (AFC).

  19. 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.

  20. Reduction of Stored NOx on Pt/Al?O? and Pt/BaO/Al?O? Catalysts with H? and CO

    SciTech Connect (OSTI)

    Szailer, Tamas; Kwak, Ja Hun; Kim, Do Heui; Hanson, Jonathan; Peden, Charles HF; Szanyi, Janos

    2006-04-01

    In situ FTIR spectroscopy coupled with mass spectrometry, and time resolved X-ray diffraction were used to study the efficiency of nitrate reduction with CO and H? on Pt/Al?O? and Pt/BaO/Al?O? NOx storage-reduction (NSR) catalysts. Surface nitrates were generated by NO? adsorption and their reduction efficiencies were examined on the catalysts together with the analysis of the gas phase composition in the presence of the two different reductants. H? was found to be a more effective reducing agent than CO. In particular, the reduction of surface nitrates proceeds very efficiently with H? even at low temperatures (~420 K). During reduction with CO, isocyanates were observed to form on every catalyst component. These surface isocyanates, however, readily react with water to form CO? and ammonia. The thus formed NH?, in turn, reacts with stored NOx at higher temperatures (>473K) to produce N?. In the absence of H?O, the NCO species are stable to high temperatures, and removed only from the catalyst when they react with NOx thermal decomposition products to form N? and CO?. The results of this study point to a complex reaction mechanism that involves the removal of surface oxygen atoms from the Pt particles by either H? or CO, the direct reduction of stored NOx with H? (low temperature NOx reduction), the formation and the subsequent hydrolysis of NCO species, as well as the direct reaction of NCO with decomposing NOx (high temperature NOx reduction).