National Library of Energy BETA

Sample records for room temperature ionic

  1. Microstructure of room temperature ionic liquids at stepped graphite electrodes

    SciTech Connect (OSTI)

    Feng, Guang; Li, Song; Zhao, Wei; Cummings, Peter T.

    2015-07-14

    Molecular dynamics simulations of room temperature ionic liquid (RTIL) [emim][TFSI] at stepped graphite electrodes were performed to investigate the influence of the thickness of the electrode surface step on the microstructure of interfacial RTILs. A strong correlation was observed between the interfacial RTIL structure and the step thickness in electrode surface as well as the ion size. Specifically, when the step thickness is commensurate with ion size, the interfacial layering of cation/anion is more evident; whereas, the layering tends to be less defined when the step thickness is close to the half of ion size. Furthermore, two-dimensional microstructure of ion layers exhibits different patterns and alignments of counter-ion/co-ion lattice at neutral and charged electrodes. As the cation/anion layering could impose considerable effects on ion diffusion, the detailed information of interfacial RTILs at stepped graphite presented here would help to understand the molecular mechanism of RTIL-electrode interfaces in supercapacitors.

  2. Microstructure of room temperature ionic liquids at stepped graphite electrodes

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

    Feng, Guang; Li, Song; Zhao, Wei; Cummings, Peter T.

    2015-07-14

    Molecular dynamics simulations of room temperature ionic liquid (RTIL) [emim][TFSI] at stepped graphite electrodes were performed to investigate the influence of the thickness of the electrode surface step on the microstructure of interfacial RTILs. A strong correlation was observed between the interfacial RTIL structure and the step thickness in electrode surface as well as the ion size. Specifically, when the step thickness is commensurate with ion size, the interfacial layering of cation/anion is more evident; whereas, the layering tends to be less defined when the step thickness is close to the half of ion size. Furthermore, two-dimensional microstructure of ionmore » layers exhibits different patterns and alignments of counter-ion/co-ion lattice at neutral and charged electrodes. As the cation/anion layering could impose considerable effects on ion diffusion, the detailed information of interfacial RTILs at stepped graphite presented here would help to understand the molecular mechanism of RTIL-electrode interfaces in supercapacitors.« less

  3. Decoupling charge transport from the structural dynamics in room temperature ionic liquids

    SciTech Connect (OSTI)

    Griffin, Phillip; Agapov, Alexander L; Kisliuk, Alexander; Sun, Xiao-Guang; Dai, Sheng; Novikov, Vladimir; Sokolov, Alexei P

    2011-01-01

    Light scattering and dielectric spectroscopy measurements were performed on the room temperature ionic liquid (RTIL) [C4mim][NTf2] in a broad temperature and frequency range. Ionic conductivity was used to estimate self-diffusion of ions, while light scattering was used to study structural relaxation. We demonstrate that the ionic diffusion decouples from the structural relaxation process as the temperature of the sample decreases toward Tg. The strength of the decoupling appears to be significantly lower than that expected for a supercooled liquid of similar fragility. The structural relaxation process in the RTIL follows well the high-temperature mode coupling theory (MCT) scenario. Using the MCT analysis we estimated the dynamic crossover temperature in [C4mim][NTf2] to be Tc 225 5 K. However, our analysis reveals no sign of the dynamic crossover in the ionic diffusion process.

  4. EXAFS investigations of the mechanism of facilitated ion transfer into a room-temperature ionic liquid.

    SciTech Connect (OSTI)

    Jensen, M. P.; Dzielawa, J. A.; Rickert, P.; Dietz, M. L.; Chemistry

    2002-09-11

    The Sr(II)-crown ether complexes formed in a room-temperature ionic liquid (RTIL), 1-methyl-3-pentylimidazolium bis[(trifluoromethyl)sulfonyl]amide, have been studied by X-ray absorption fine structure measurements at the Sr K-edge. When a Sr(NO{sub 3}){sub 2}-crown ether complex is directly dissolved in a water-saturated RTIL, both nitrate ligands and the crown ether coordinate the Sr, as observed in a conventional two-phase water-octanol system. When the cationic Sr-crown ether complex is created in a two-phase water-RTIL system, however, only cationic Sr-crown ether complexes are observed in the RTIL phase. This difference in the coordination complexes arises from differences in the mechanism of cation extraction between the RTIL and conventional molecular organic solvents, a finding with important implications for synthesis, catalysis, and ion separations using two-phase water-RTIL systems.

  5. Hydrogen-bonding interactions and protic equilibria in room-temperature ionic liquids containing crown ethers.

    SciTech Connect (OSTI)

    Marin, T.; Shkrob, I.; Dietz, M.

    2011-04-14

    Nuclear magnetic resonance (NMR) spectroscopy has been used to study hydrogen-bonding interactions between water, associated and dissociated acids (i.e., nitric and methanesulfonic acids), and the constituent ions of several water-immiscible room-temperature ionic liquids (ILs). In chloroform solutions also containing a crown ether (CE), water molecules strongly associate with the IL ions, and there is rapid proton exchange between these bound water molecules and hydronium associated with the CE. In neat ILs, the acids form clusters differing in their degree of association and ionization, and their interactions with the CEs are weak. The CE can either promote proton exchange between different clusters in IL solution when their association is weak or inhibit such exchange when the association is strong. Even strongly hydrophobic ILs are shown to readily extract nitric acid from aqueous solution, typically via the formation of a 1:1:1 {l_brace}H{sub 3}O{sup +} {center_dot} CE{r_brace}NO{sub 3}{sup -} complex. In contrast, the extraction of methanesulfonic acid is less extensive and proceeds mainly by IL cation-hydronium ion exchange. The relationship of these protic equilibria to the practical application of hydrophobic ILs (e.g., in spent nuclear fuel reprocessing) is discussed.

  6. High-Permeance Room-Temperature Ionic-Liquid-Based Membranes for CO2/N-2 Separation

    SciTech Connect (OSTI)

    Zhou, JS; Mok, MM; Cowan, MG; McDanel, WM; Carlisle, TK; Gin, DL; Noble, RD

    2014-12-24

    We have developed and fabricated thin-film composite (TFC) membranes with an active layer consisting of a room-temperature ionic liquid/polymerized (room-temperature ionic liquid) [i.e., (RTIL)/poly(RTIL)] composite material. The resulting membrane has a CO2 permeance of 6100 +/- 400 GPU (where 1 GPU = 10(-6) cm(3)/(cm(2) s cmHg)) and an ideal CO2/N-2 selectivity of 22 +/- 2. This represents a new membrane with state-of-the-art CO2 permeance and good CO2/N-2 selectivity. To our knowledge, this is the first example of a TFC gas separation membrane composed of an RTIL-containing active layer.

  7. Fission-Product Separation Based on Room-Temperature Ionic Liquids

    SciTech Connect (OSTI)

    Luo, Huimin; Hussey, Charles L.

    2005-09-30

    The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

  8. Fission-Product Separation Based on Room-Temperature Ionic Liquids

    SciTech Connect (OSTI)

    Luo, Huimin; Rogers, Robin D.; Dai, Sheng, Dai; Bonnesen, Peter V.; Buchanan, A. C. III; Hussey, Charles L.

    2003-06-16

    The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

  9. Metal-air cell comprising an electrolyte with a room temperature ionic liquid and hygroscopic additive

    DOE Patents [OSTI]

    Friesen, Cody A.; Krishnan, Ramkumar; Tang, Toni; Wolfe, Derek

    2014-08-19

    An electrochemical cell comprising an electrolyte comprising water and a hydrophobic ionic liquid comprising positive ions and negative ions. The electrochemical cell also includes an air electrode configured to absorb and reduce oxygen. A hydrophilic or hygroscopic additive modulates the hydrophobicity of the ionic liquid to maintain a concentration of the water in the electrolyte is between 0.001 mol % and 25 mol %.

  10. 81929 - Fission-Product Separation Based on Room - Temperature Ionic Liquids

    SciTech Connect (OSTI)

    Robin D. Rogers

    2004-12-09

    This project has demonstrated that Sr2+ and Cs+ can be selectively extracted from aqueous solutions into ionic liquids using crown ethers and that unprecedented large distribution coefficients can be achieved for these fission products. The volume of secondary wastes can be significantly minimized with this new separation technology. Through the current EMSP funding, the solvent extraction technology based on ionic liquids has been shown to be viable and can potentially provide the most efficient separation of problematic fission products from high level wastes. The key results from the current funding period are the development of highly selective extraction process for cesium ions based on crown ethers and calixarenes, optimization of selectivities of extractants via systematic change of ionic liquids, and investigation of task-specific ionic liquids incorporating both complexant and solvent characteristics.

  11. NOvel Fission Product Separation Based on Room-Temperature Ionic liquids

    SciTech Connect (OSTI)

    Hussey, Charles L.

    2005-11-13

    The effective extraction of Cs+ and Sr2+ into a relatively new and heretofore untested hydrophobic ionic liquid, tri-n-butylmethylammonium bis[(trifluoromethyl)sulfonyl]imide was demonstrated with calix[4]arene-bis(tert-octylbenzo-crown-6) and dicyclohexano-18-crown-6, respectively. The coordinated Cs+ and Sr2+ were subsequently removed from the ionic liquid extraction solvent by an electrochemical reduction process carried out at mercury electrodes. This process is non-destructive, permitting the ionic liquid and ionophores to be recycled. Although the process is based on mercury electrodes, this is a benefit rather than a detriment because the liquid mercury containing the Cs and Sr can be easily transported to another electrochemical cell where the Cs and Sr could be electrochemically recovered from the mercury amalgam and concentrated into a minimum volume of water or some other inexpensive solvent. This should facilitate the development of a suitable waste form for the extracted Cs+ and Sr2+. Thus, the feasibility of the proposed ionic liquid-based extraction cycle for the removal of 137Cs+ and 90Sr2+ from simulated aqueous tank waste was demonstrated.

  12. Room-temperature ionic liquid-amine solutions: tunable solvents for efficient and reversible capture of CO{sub 2}

    SciTech Connect (OSTI)

    Dean Camper; Jason E. Bara; Douglas L. Gin; Richard D. Noble

    2008-11-05

    Solutions of room-temperature ionic liquids (RTILs) and commercially available amines were found to be effective for the capture of CO{sub 2} as carbamate salts. RTIL solutions containing 50 mol % (16% v/v) monoethanolamine (MEA) are capable of rapid and reversible capture of 1 mol of CO{sub 2} per 2 moles MEA to give an insoluble MEA-carbamate precipitate that helps to drive the capture reaction (as opposed to aqueous amine systems). Diethanolamine (DEA) can also be used in the same manner for CO{sub 2} capture in RTILs containing a pendant hydroxyl group. The captured CO{sub 2} in the resulting RTIL-carbamate salt mixtures can be readily released by either heating and/or subjecting them to reduced pressure. Using this unprecedented and industrially attractive mixing approach, the desirable properties of RTILs (i.e., nonvolatility, enhancedCO{sub 2} solubility, lower heat capacities) can be combined with the performance of amines for CO{sub 2} capture without the use of specially designed, functionalized 'task-specific' ionic liquids. By mixing RTILs with commercial amines, reactive solvents with a wide range of amine loading levels can be tailored to capture CO{sub 2} in a variety of conditions and processes. These RTIL-amine solutions behave similarly to their water-based counterparts but may offer many advantages, including increased energy efficiency, compared to current aqueous amine technologies.

  13. Fission-Product Separation Based on Room-Temperature Ionic Liquids (OR08SP24-16)

    SciTech Connect (OSTI)

    Luo, Huimin; Bonnesen, Peter V.; Rogers, Robin D.; Dai, Sheng; Buchanan, A. C. III; Hussey, Charles L.

    2002-06-15

    The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

  14. Direct Electrodeposition of UO2 from Uranyl Bis(trifluoromethanesulfonyl)imide Dissolved in 1-Ethyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide Room Temperature Ionic Liquid System

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

    Freiderich, John W.; Wanigasekara, Eranda P.; Sun, Xiao-Guang; Meisner, Roberta Ann; Meyer, III, Harry M.; Luo, Huimin; Delmau, Laetitia Helene; Dai, Sheng; Moyer, Bruce A

    2013-11-11

    Our study demonstrates a direct electrodeposition of UO2 at a Pt cathode from a solution of uranyl bis(trifluoromethanesulfonyl)imide [UO2(NTf2)2)] in a bulk room-temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM+NTf2–). Cyclic voltammetry (CV) studies revealed two reduction waves corresponding to the conversion of uranium(VI) to uranium(IV), and a mechanism for the overall electroreduction is proposed. A controlled-potential experiment was performed, holding the reduction potential at–1.0 V for 24 h to obtain a brown-black deposit of UO2 on the Pt cathode. The Faradaic efficiency of the reduction process was determined to be >80%. The UO2deposit was characterized by powder X-ray diffraction (XRD)more » and X-ray photoelectron spectroscopy (XPS).« less

  15. Direct Electrodeposition of UO2 from Uranyl Bis(trifluoromethanesulfonyl)imide Dissolved in 1-Ethyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide Room Temperature Ionic Liquid System

    SciTech Connect (OSTI)

    Freiderich, John W.; Wanigasekara, Eranda P.; Sun, Xiao-Guang; Meisner, Roberta Ann; Meyer, III, Harry M.; Luo, Huimin; Delmau, Laetitia Helene; Dai, Sheng; Moyer, Bruce A

    2013-11-11

    Our study demonstrates a direct electrodeposition of UO2 at a Pt cathode from a solution of uranyl bis(trifluoromethanesulfonyl)imide [UO2(NTf2)2)] in a bulk room-temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM+NTf2). Cyclic voltammetry (CV) studies revealed two reduction waves corresponding to the conversion of uranium(VI) to uranium(IV), and a mechanism for the overall electroreduction is proposed. A controlled-potential experiment was performed, holding the reduction potential at–1.0 V for 24 h to obtain a brown-black deposit of UO2 on the Pt cathode. The Faradaic efficiency of the reduction process was determined to be >80%. The UO2deposit was characterized by powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

  16. Room Temperature Dispenser Photocathode Using Elemental Cesium

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

    Room Temperature Dispenser Photocathode Using Elemental Cesium Room Temperature Dispenser Photocathode Using Elemental Cesium Los Alamos National Laboratory (LANL) researchers have...

  17. Extraction and separation of thorium(IV) from lanthanides(III) with room-temperature ionic liquids containing primary amine N{sub 1923}

    SciTech Connect (OSTI)

    Zuo, Y.; Chen, J.; Bai, Y.; Li, D.Q.

    2008-07-01

    The extraction behavior of Th(IV) by primary amine N{sub 1923} in imidazolium-based ionic liquid namely 1-octyl-3-methylimidazolium hexafluorophosphate (N{sub 1923}/IL) was studied in this paper. Results showed that N{sub 1923}/IL had poorer extraction ability for Th(IV) than N{sub 1923} in n-heptane (N{sub 1923}/HEP). The separation coefficients between Th(IV) and lanthanides(III) ({beta}{sub Th/Ln}) were obtained and compared with those in the N{sub 1923}/HEP system. On this basis, we made a preliminary assessment for the possibility of using ionic liquids as solvents for the separation of Th(IV) from lanthanides(III) sulfate in a clean process. (authors)

  18. Room Temperature Ferrimagnetism and Ferroelectricity in Strained...

    Office of Scientific and Technical Information (OSTI)

    The demonstration of strain induced, high temperature multiferroism is a prom- ising development for future spintronic and memory applications at room temperature and above. 1. ...

  19. Room temperature ferrimagnetism and ferroelectricity in strained...

    Office of Scientific and Technical Information (OSTI)

    The demonstration of strain induced, high temperature multiferroism is a promising development for future spintronic and memory applications at room temperature and above. Authors: ...

  20. Topological Insulators at Room Temperature

    SciTech Connect (OSTI)

    Zhang, Haijun; Liu, Chao-Xing; Qi, Xiao-Liang; Dai, Xi; Fang, Zhong; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-25

    Topological insulators are new states of quantum matter with surface states protected by the time-reversal symmetry. In this work, we perform first-principle electronic structure calculations for Sb{sub 2}Te{sub 3}, Sb{sub 2}Se{sub 3}, Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} crystals. Our calculations predict that Sb{sub 2}Te{sub 3}, Bi{sub 2}T e{sub 3} and Bi{sub 2}Se{sub 3} are topological insulators, while Sb{sub 2}Se{sub 3} is not. In particular, Bi{sub 2}Se{sub 3} has a topologically non-trivial energy gap of 0.3eV , suitable for room temperature applications. We present a simple and unified continuum model which captures the salient topological features of this class of materials. These topological insulators have robust surface states consisting of a single Dirac cone at the {Lambda} point.

  1. Determining Camera Gain in Room Temperature Cameras

    SciTech Connect (OSTI)

    Joshua Cogliati

    2010-12-01

    James R. Janesick provides a method for determining the amplification of a CCD or CMOS camera when only access to the raw images is provided. However, the equation that is provided ignores the contribution of dark current. For CCD or CMOS cameras that are cooled well below room temperature, this is not a problem, however, the technique needs adjustment for use with room temperature cameras. This article describes the adjustment made to the equation, and a test of this method.

  2. Room-temperature creep of tantalum tritides

    SciTech Connect (OSTI)

    Schober, T.; Trinkaus, H. )

    1990-06-15

    We report on long-term creep experiments on dilute tantalum tritides at room temperature. Significant deviations of the recorded strain rates from isotropic swelling are found above approximately 30 MPa. We attribute this room-temperature creep to a stress-induced preferential dislocation loop punching by bubbles in crystallographic directions close the stress axis. Quantitative estimates show that this mechanism can indeed account for the observed creep rates.

  3. Metal-air low temperature ionic liquid cell

    SciTech Connect (OSTI)

    Friesen, Cody A; Buttry, Daniel A

    2014-11-25

    The present application relates to an electrochemical metal-air cell in which a low temperature ionic liquid is used.

  4. New Flexible Channels for Room Temperature Tunneling Field Effect...

    Office of Scientific and Technical Information (OSTI)

    New Flexible Channels for Room Temperature Tunneling Field Effect Transistors Citation Details In-Document Search Title: New Flexible Channels for Room Temperature Tunneling Field ...

  5. Imprinting bulk amorphous alloy at room temperature

    SciTech Connect (OSTI)

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.

  6. Imprinting bulk amorphous alloy at room temperature

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

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the abilitymore » of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.« less

  7. Atomically resolved force microscopy at room temperature

    SciTech Connect (OSTI)

    Morita, Seizo

    2014-04-24

    Atomic force microscopy (AFM) can now not only image individual atoms but also construct atom letters using atom manipulation method even at room temperature (RT). Therefore, the AFM is the second generation atomic tool following the scanning tunneling microscopy (STM). However the AFM can image even insulating atoms, and also directly measure/map the atomic force and potential at the atomic scale. Noting these advantages, we have been developing a bottom-up nanostructuring system at RT based on the AFM. It can identify chemical species of individual atoms and then manipulate selected atom species to the predesigned site one-by-one to assemble complex nanostructures consisted of multi atom species at RT. Here we introduce our results toward atom-by-atom assembly of composite nanostructures based on the AFM at RT including the latest result on atom gating of nano-space for atom-by-atom creation of atom clusters at RT for semiconductor surfaces.

  8. Electrodrift purification of materials for room temperature radiation detectors

    DOE Patents [OSTI]

    James, R.B.; Van Scyoc, J.M. III; Schlesinger, T.E.

    1997-06-24

    A method of purifying nonmetallic, crystalline semiconducting materials useful for room temperature radiation detecting devices by applying an electric field across the material is disclosed. The present invention discloses a simple technology for producing purified ionic semiconducting materials, in particular PbI{sub 2} and preferably HgI{sub 2}, which produces high yields of purified product, requires minimal handling of the material thereby reducing the possibility of introducing or reintroducing impurities into the material, is easy to control, is highly selective for impurities, retains the stoichiometry of the material and employs neither high temperatures nor hazardous materials such as solvents or liquid metals. An electric field is applied to a bulk sample of the material causing impurities present in the sample to drift in a preferred direction. After all of the impurities have been transported to the ends of the sample the current flowing through the sample, a measure of the rate of transport of mobile impurities, falls to a low, steady state value, at which time the end sections of the sample where the impurities have concentrated are removed leaving a bulk sample of higher purity material. Because the method disclosed here only acts on the electrically active impurities, the stoichiometry of the host material remains substantially unaffected. 4 figs.

  9. Electrodrift purification of materials for room temperature radiation detectors

    DOE Patents [OSTI]

    James, Ralph B.; Van Scyoc, III, John M.; Schlesinger, Tuviah E.

    1997-06-24

    A method of purifying nonmetallic, crystalline semiconducting materials useful for room temperature radiation detecting devices by applying an electric field across the material. The present invention discloses a simple technology for producing purified ionic semiconducting materials, in particular PbI.sub.2 and preferably HgI.sub.2, which produces high yields of purified product, requires minimal handling of the material thereby reducing the possibility of introducing or reintroducing impurities into the material, is easy to control, is highly selective for impurities, retains the stoichiometry of the material and employs neither high temperatures nor hazardous materials such as solvents or liquid metals. An electric field is applied to a bulk sample of the material causing impurities present in the sample to drift in a preferred direction. After all of the impurities have been transported to the ends of the sample the current flowing through the sample, a measure of the rate of transport of mobile impurities, falls to a low, steady state value, at which time the end sections of the sample where the impurities have concentrated are removed leaving a bulk sample of higher purity material. Because the method disclosed here only acts on the electrically active impurities, the stoichiometry of the host material remains substantially unaffected.

  10. Time dependent deformation of metals at room temperature. (Conference...

    Office of Scientific and Technical Information (OSTI)

    Title: Time dependent deformation of metals at room temperature. Abstract not provided. Authors: Deibler, Lisa Anne ; Boyce, Brad Lee ; Puskar, Joseph D. Publication Date: ...

  11. Argonne scientists announce first room-temperature magnetic skyrmion...

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

    left to right: Argonne researchers Wanjun Jiang, Suzanne G.E. te Velthuis, and Axel Hoffman published a new way to make magnetic skyrmion bubbles at room temperature. Photo by...

  12. Neutron absorbing room temperature vulcanizable silicone rubber compositions

    DOE Patents [OSTI]

    Zoch, Harold L.

    1979-11-27

    A neutron absorbing composition comprising a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron compound in this application is boron carbide.

  13. Control and Room Temperature Optimization of Energy Efficient Buildings

    SciTech Connect (OSTI)

    Djouadi, Seddik M; Kuruganti, Phani Teja

    2012-01-01

    The building sector consumes a large part of the energy used in the United States and is responsible for nearly 40% of greenhouse gas emissions. It is therefore economically and environmentally important to reduce the building energy consumption to realize massive energy savings. In this paper, a method to control room temperature in buildings is proposed. The approach is based on a distributed parameter model represented by a three dimensional (3D) heat equation in a room with heater/cooler located at ceiling. The latter is resolved using finite element methods, and results in a model for room temperature with thousands of states. The latter is not amenable to control design. A reduced order model of only few states is then derived using Proper Orthogonal Decomposition (POD). A Linear Quadratic Regulator (LQR) is computed based on the reduced model, and applied to the full order model to control room temperature.

  14. Room-temperature magnetoelectric multiferroic thin films and applications thereof

    DOE Patents [OSTI]

    Katiyar, Ram S; Kuman, Ashok; Scott, James F.

    2014-08-12

    The invention provides a novel class of room-temperature, single-phase, magnetoelectric multiferroic (PbFe.sub.0.67W.sub.0.33O.sub.3).sub.x (PbZr.sub.0.53Ti.sub.0.47O.sub.3).sub.1-x (0.2.ltoreq.x.ltoreq.0.8) (PFW.sub.x-PZT.sub.1-x) thin films that exhibit high dielectric constants, high polarization, weak saturation magnetization, broad dielectric temperature peak, high-frequency dispersion, low dielectric loss and low leakage current. These properties render them to be suitable candidates for room-temperature multiferroic devices. Methods of preparation are also provided.

  15. Room temperature ferromagnetism in conducting α-(In{sub 1-x...

    Office of Scientific and Technical Information (OSTI)

    Room temperature ferromagnetism in conducting -(Insub 1-xFesub x)sub 2Osub 3 alloy films Citation Details In-Document Search Title: Room temperature ferromagnetism in ...

  16. Optically activated sub-millimeter dielectric relaxation in amorphous thin film silicon at room temperature

    SciTech Connect (OSTI)

    Rahman, Rezwanur; Ohno, Tim R.; Taylor, P. C.; Scales, John A.

    2014-05-05

    Knowing the frequency-dependent photo-induced complex conductivity of thin films is useful in the design of photovoltaics and other semi-conductor devices. For example, annealing in the far-infrared could in principle be tailored to the specific dielectric properties of a particular sample. The frequency dependence of the conductivity (whether dark or photo-induced) also gives insight into the effective dimensionality of thin films (via the phonon density of states) as well as the presence (or absence) of free carriers, dopants, defects, etc. Ultimately, our goal is to make low-noise, phase-sensitive room temperature measurements of the frequency-dependent conductivity of thin films from microwave frequencies into the far-infrared; covering, the frequency range from ionic and dipole relaxation to atomic and electronic processes. To this end, we have developed a high-Q (quality factor) open cavity resonator capable of resolving the complex conductivity of sub-micron films in the range of 100350?GHz (0.10.35 THz, or 0.41?meV). In this paper, we use a low-power green laser to excite bound charges in high-resistivity amorphous silicon thin film. Even at room temperature, we can resolve both the dark conductivity and photo-induced changes associated with dielectric relaxation and possibly some small portion of free carriers.

  17. CuInP2S6 Room Temperature Layered Ferroelectric

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

    Belianinov, Alex; He, Qian; Dziaugys, Andrius; Maksymovych, Petro; Eliseev, Eugene; Borisevich, Albina Y.; Morozovska, Anna N.; Banys, Juras; Vysochanskii, Yulian; Kalinin, Sergei V.

    2015-05-01

    In this paper, we explore ferroelectric properties of cleaved 2-D flakes of copper indium thiophosphate, CuInP2S6 (CITP), and probe size effects along with limits of ferroelectric phase stability, by ambient and ultra high vacuum scanning probe microscopy. CITP belongs to the only material family known to display ferroelectric polarization in a van der Waals, layered crystal at room temperature and above. Our measurements directly reveal stable, ferroelectric polarization as evidenced by domain structures, switchable polarization, and hysteresis loops. We found that at room temperature the domain structure of flakes thicker than 100 nm is similar to the cleaved bulk surfaces,more » whereas below 50 nm polarization disappears. We ascribe this behavior to a well-known instability of polarization due to depolarization field. Furthermore, polarization switching at high bias is also associated with ionic mobility, as evidenced both by macroscopic measurements and by formation of surface damage under the tip at a bias of 4 V—likely due to copper reduction. Mobile Cu ions may therefore also contribute to internal screening mechanisms. Finally, the existence of stable polarization in a van-der-Waals crystal naturally points toward new strategies for ultimate scaling of polar materials, quasi-2D, and single-layer materials with advanced and nonlinear dielectric properties that are presently not found in any members of the growing “graphene family”.« less

  18. CuInP2S6 Room Temperature Layered Ferroelectric

    SciTech Connect (OSTI)

    Belianinov, Alex; He, Qian; Dziaugys, Andrius; Maksymovych, Petro; Eliseev, Eugene; Borisevich, Albina Y.; Morozovska, Anna N.; Banys, Juras; Vysochanskii, Yulian; Kalinin, Sergei V.

    2015-05-01

    In this paper, we explore ferroelectric properties of cleaved 2-D flakes of copper indium thiophosphate, CuInP2S6 (CITP), and probe size effects along with limits of ferroelectric phase stability, by ambient and ultra high vacuum scanning probe microscopy. CITP belongs to the only material family known to display ferroelectric polarization in a van der Waals, layered crystal at room temperature and above. Our measurements directly reveal stable, ferroelectric polarization as evidenced by domain structures, switchable polarization, and hysteresis loops. We found that at room temperature the domain structure of flakes thicker than 100 nm is similar to the cleaved bulk surfaces, whereas below 50 nm polarization disappears. We ascribe this behavior to a well-known instability of polarization due to depolarization field. Furthermore, polarization switching at high bias is also associated with ionic mobility, as evidenced both by macroscopic measurements and by formation of surface damage under the tip at a bias of 4 V—likely due to copper reduction. Mobile Cu ions may therefore also contribute to internal screening mechanisms. Finally, the existence of stable polarization in a van-der-Waals crystal naturally points toward new strategies for ultimate scaling of polar materials, quasi-2D, and single-layer materials with advanced and nonlinear dielectric properties that are presently not found in any members of the growing “graphene family”.

  19. High Temperature/Low Humidity Polymer Electrolytes Derived from Ionic Liquids

    Broader source: Energy.gov [DOE]

    Presentation on High Temperature/Low Humidity Polymer Electrolytes Derived from Ionic Liquids to the High Temperature Membrane Working Group Meeting held in Arlington, Virginia, May 26,2005.

  20. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    SciTech Connect (OSTI)

    Ravikumar, Patta; Kisan, Bhagaban; Perumal, A.

    2015-08-15

    We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO) band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μ{sub B}/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (T{sub C}) around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR) studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high T{sub C} and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  1. Room-temperature ferromagnetism in cerium dioxide powders

    SciTech Connect (OSTI)

    Rakhmatullin, R. M. Pavlov, V. V.; Semashko, V. V.; Korableva, S. L.

    2015-08-15

    Room-temperature ferromagnetism is detected in a CeO{sub 2} powder with a grain size of about 35 nm and a low (<0.1 at %) manganese and iron content. The ferromagnetism in a CeO{sub 2} sample with a submicron crystallite size and the same manganese and iron impurity content is lower than in the nanocrystalline sample by an order of magnitude. Apart from ferromagnetism, both samples exhibit EPR spectra of localized paramagnetic centers, the concentration of which is lower than 0.01 at %. A comparative analysis of these results shows that the F-center exchange (FCE) mechanism cannot cause ferromagnetism. This conclusion agrees with the charge-transfer ferromagnetism model proposed recently.

  2. Room-temperature LINAC structures for the spallation neutron source

    SciTech Connect (OSTI)

    Billen, J. H.; Young, L. M.; Kurennoy, S.; Crandall, K. R.

    2001-04-01

    Los Alamos National Laboratory is building room-temperature rf accelerating structures for the Spallation Neutron Source (SNS). These structures, for H{sup -} ions, consist of six 402.5-MHz, 2-MW drift-tube linac (DTL) tanks from 2.5 to 87 MeV followed by four 805-MHz, 4-MW coupled-cavity linac (CCL) modules to 186 MeV. The DTL uses permanent magnet quadrupoles inside the drift tubes arranged in a 6{beta}{lambda} FFODDO lattice with every third drift tube available for diagnostics and steering. The CCL uses a 13{beta}{lambda} FODO electromagnetic quadrupole lattice. Diagnostics and magnets occupy the 2.5{beta}{lambda} spaces between 8-cavity segments. This paper discusses design of the rf cavities and low-power modeling work.

  3. New Flexible Channels for Room Temperature Tunneling Field Effect Transistors

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

    Hao, Boyi; Asthana, Anjana; Hazaveh, Paniz Khanmohammadi; Bergstrom, Paul L.; Banyai, Douglas; Savaikar, Madhusudan A.; Jaszczak, John A.; Yap, Yoke Khin

    2016-02-05

    Tunneling field effect transistors (TFETs) have been proposed to overcome the fundamental issues of Si based transistors, such as short channel effect, finite leakage current, and high contact resistance. Unfortunately, most if not all TFETs are operational only at cryogenic temperatures. Here we report that iron (Fe) quantum dots functionalized boron nitride nanotubes (QDs-BNNTs) can be used as the flexible tunneling channels of TFETs at room temperatures. The electrical insulating BNNTs are used as the one-dimensional (1D) substrates to confine the uniform formation of Fe QDs on their surface as the flexible tunneling channel. Consistent semiconductor-like transport behaviors under variousmore » bending conditions are detected by scanning tunneling spectroscopy in a transmission electron microscopy system (insitu STM-TEM). Ultimately, as suggested by computer simulation, the uniform distribution of Fe QDs enable an averaging effect on the possible electron tunneling pathways, which is responsible for the consistent transport properties that are not sensitive to bending.« less

  4. Robust isothermal electric control of exchange bias at room temperature

    SciTech Connect (OSTI)

    He, X.; Vescovo, E.; Wang, Y.; Caruso, A.N.; Belashchenko, K.D.; Dowben, P.A.; Binek, C.

    2010-06-20

    Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with high-speed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr{sub 2}O{sub 3} has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr{sub 2}O{sub 3} single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias field between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This effect reflects the switching of the bulk antiferromagnetic domain state and the interface magnetization coupled to it. The switchable exchange bias sets in exactly at the bulk Neel temperature.

  5. Phosphonium-based ionic liquids and uses

    DOE Patents [OSTI]

    Del Sesto, Rico E; Koppisch, Andrew T; Lovejoy, Katherine S; Purdy, Geraldine M

    2014-12-30

    Phosphonium-based room temperature ionic liquids ("RTILs") were prepared. They were used as matrices for Matrix-Assisted Laser Desorption Ionization (MALDI) mass spectrometry and also for preparing samples of dyes for analysis.

  6. Cross-linking of polytetrafluoroethylene during room-temperature irradiation

    SciTech Connect (OSTI)

    Pugmire, David L; Wetteland, Chris J; Duncan, Wanda S; Lakis, Rollin E; Schwartz, Daniel S

    2008-01-01

    Exposure of polytetrafluoroethylene (PTFE) to {alpha}-radiation was investigated to detennine the physical and chemical effects, as well as to compare and contrast the damage mechanisms with other radiation types ({beta}, {gamma}, or thermal neutron). A number of techniques were used to investigate the chemical and physical changes in PTFE after exposure to {alpha}-radiation. These techniques include: Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and fluorescence spectroscopy. Similar to other radiation types at low doses, the primary damage mechanism for the exposure of PTFE to {alpha}-radiation appears to be chain scission. Increased doses result in a change-over of the damage mechanism to cross-linking. This result is not observed for any radiation type other than {alpha} when irradiation is performed at room temperature. Finally, at high doses, PTFE undergoes mass-loss (via smallfluorocarbon species evolution) and defluorination. The amount and type of damage versus sample depth was also investigated. Other types of radiation yield damage at depths on the order of mm to cm into PTFE due to low linear energy transfer (LET) and the correspondingly large penetration depths. By contrast, the {alpha}-radiation employed in this study was shown to only induce damage to a depth of approximately 26 {mu}m, except at very high doses.

  7. Instantaneous radioiodination of rose bengal at room temperature and a cold kit therefor

    DOE Patents [OSTI]

    O'Brien, Jr., Harold A.; Hupf, Homer B.; Wanek, Philip M.

    1981-01-01

    The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free .sup.125 I.sup.- is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

  8. Ionic liquids and ionic liquid acids with high temperature stability for fuel cell and other high temperature applications, method of making and cell employing same

    DOE Patents [OSTI]

    Angell, C. Austen; Xu, Wu; Belieres, Jean-Philippe; Yoshizawa, Masahiro

    2011-01-11

    Disclosed are developments in high temperature fuel cells including ionic liquids with high temperature stability and the storage of inorganic acids as di-anion salts of low volatility. The formation of ionically conducting liquids of this type having conductivities of unprecedented magnitude for non-aqueous systems is described. The stability of the di-anion configuration is shown to play a role in the high performance of the non-corrosive proton-transfer ionic liquids as high temperature fuel cell electrolytes. Performance of simple H.sub.2(g) electrolyte/O.sub.2(g) fuel cells with the new electrolytes is described. Superior performance both at ambient temperature and temperatures up to and above 200.degree. C. are achieved. Both neutral proton transfer salts and the acid salts with HSO.sup.-.sub.4 anions, give good results, the bisulphate case being particularly good at low temperatures and very high temperatures. The performance of all electrolytes is improved by the addition of a small amount of involatile base of pK.sub.a value intermediate between those of the acid and base that make the bulk electrolyte. The preferred case is the imidazole-doped ethylammonium hydrogensulfate which yields behavior superior in all respects to that of the industry standard phosphoric acid electrolyte.

  9. Synthesis of ionic liquids

    DOE Patents [OSTI]

    Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN

    2008-09-09

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic liqand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  10. Synthesis of ionic liquids

    DOE Patents [OSTI]

    Dai, Sheng (Knoxville, TN); Luo, Huimin (Knoxville, TN)

    2011-11-01

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic ligand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  11. Room temperature single-photon detectors for high bit rate quantum key distribution

    SciTech Connect (OSTI)

    Comandar, L. C.; Patel, K. A.; Frhlich, B. Lucamarini, M.; Sharpe, A. W.; Dynes, J. F.; Yuan, Z. L.; Shields, A. J.; Penty, R. V.

    2014-01-13

    We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50?km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.

  12. Ordered iron aluminide alloys having an improved room-temperature ductility and method thereof

    DOE Patents [OSTI]

    Sikka, Vinod K.

    1992-01-01

    A process is disclosed for improving the room temperature ductility and strength of iron aluminide intermetallic alloys. The process involves thermomechanically working an iron aluminide alloy by means which produce an elongated grain structure. The worked alloy is then heated at a temperature in the range of about 650.degree. C. to about 800.degree. C. to produce a B2-type crystal structure. The alloy is rapidly cooled in a moisture free atmosphere to retain the B2-type crystal structure at room temperature, thus providing an alloy having improved room temperature ductility and strength.

  13. Microstructure evolution in Xe-irradiated UO2 at room temperature

    SciTech Connect (OSTI)

    L.F. He; J. Pakarinen; M.A. Kirk; J. Gan; A.T. Nelson; X.-M. Bai; A. El-Azab; T.R. Allen

    2014-07-01

    In situ Transmission Electron Microscopy was conducted for single crystal UO2 to understand the microstructure evolution during 300 keV Xe irradiation at room temperature. The dislocation microstructure evolution was shown to occur as nucleation and growth of dislocation loops at low irradiation doses, followed by transformation to extended dislocation segments and tangles at higher doses. Xe bubbles with dimensions of 1-2 nm were observed after room-temperature irradiation. Electron Energy Loss Spectroscopy indicated that UO2 remained stoichiometric under room temperature Xe irradiation.

  14. High temperature thermoplastic elastomers synthesized by living anionic polymerization in hydrocarbon solvent at room temperature

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

    Schlegel, Ralf; Williams, Katherine; Voyloy, Dimitry; Steren, Carlos A.; Goodwin, Andrew; Coughlin, E. Bryan; Gido, Samuel; Beiner, Mario; Hong, Kunlun; Kang, Nam -Goo; et al

    2016-03-30

    We present the synthesis and characterization of a new class of high temperature thermoplastic elastomers composed of polybenzofulvene–polyisoprene–polybenzofulvene (FIF) triblock copolymers. All copolymers were prepared by living anionic polymerization in benzene at room temperature. Homopolymerization and effects of additives on the glass transition temperature (Tg) of polybenzofulvene (PBF) were also investigated. Among all triblock copolymers studied, FIF with 14 vol % of PBF exhibited a maximum stress of 14.3 ± 1.3 MPa and strain at break of 1390 ± 66% from tensile tests. The stress–strain curves of FIF-10 and 14 were analyzed by a statistical molecular approach using a nonaffinemore » tube model to estimate the thermoplastic elastomer behavior. Dynamic mechanical analysis showed that the softening temperature of PBF in FIF was 145 °C, much higher than that of thermoplastic elastomers with polystyrene hard blocks. Microphase separation of FIF triblock copolymers was observed by small-angle X-ray scattering, even though long-range order was not achieved under the annealing conditions employed. Additionally, the microphase separation of the resulting triblock copolymers was examined by atomic force microscopy.« less

  15. Room-temperature lithium metal battery closer to reality > EMC2...

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

    Room-temperature lithium metal battery closer to reality February 3rd, 2016 By Tom ... The relative non-conductivity and brittleness of such barriers, however, means the battery ...

  16. Room-temperature calorimeter for x-ray free-electron lasers

    SciTech Connect (OSTI)

    Tanaka, T. Kato, M.; Saito, N.; Tono, K.; Yabashi, M.; Ishikawa, T.

    2015-09-15

    We have developed a room-temperature calorimeter for absolute radiant power measurements of x-ray free-electron lasers. This room-temperature calorimeter is an electrical substitution device based on the equivalence of electrical and radiant heating. Consequently, the measured radiant powers are traceable to electrical standards, i.e., the International System Units (SI). We demonstrated the performance of the room-temperature calorimeter by electrical power measurements (offline tests). In the offline tests, the room-temperature calorimeter was proven to be able to measure external powers up to at least 6.9 mW, which exceeds the upper limit (∼4 mW) of a cryogenic radiometer (the primary standard detector in Japan). In addition, measurement uncertainties of the room-temperature calorimeter were evaluated to be less than 1.0%, which is adequate for the radiant power measurements of x-ray free-electron lasers. An indirect comparison with the cryogenic radiometer was performed using a synchrotron radiation source to confirm the validity of the absolute radiant powers measured with the room-temperature calorimeter. The absolute radiant powers measured by the calorimeter agreed with those measured by the cryogenic radiometer within 0.6%, which is less than the relative standard uncertainty of the comparison (1.0%)

  17. Room-temperature ferroelectricity of SrTiO{sub 3} films modulated by cation concentration

    SciTech Connect (OSTI)

    Yang, Fang; Zhang, Qinghua; Yang, Zhenzhong; Gu, Junxing; Liang, Yan; Li, Wentao; Wang, Weihua; Jin, Kuijuan; Gu, Lin; Guo, Jiandong

    2015-08-24

    The room-temperature ferroelectricity of SrTiO{sub 3} is promising for oxide electronic devices controlled by multiple fields. An effective way to control the ferroelectricity is highly demanded. Here, we show that the off-centered antisite-like defects in SrTiO{sub 3} films epitaxially grown on Si (001) play the determinative role in the emergence of room-temperature ferroelectricity. The density of these defects changes with the film cation concentration sensitively, resulting in a varied coercive field of the ferroelectric behavior. Consequently, the room-temperature ferroelectricity of SrTiO{sub 3} films can be effectively modulated by tuning the temperature of metal sources during the molecular beam epitaxy growth. Such an easy and reliable modulation of the ferroelectricity enables the flexible engineering of multifunctional oxide electronic devices.

  18. Room temperature aluminum antimonide radiation detector and methods thereof

    DOE Patents [OSTI]

    Lordi, Vincenzo; Wu, Kuang Jen J.; Aberg, Daniel; Erhart, Paul; Coombs, III, Arthur W; Sturm, Benjamin W

    2015-03-03

    In one embodiment, a method for producing a high-purity single crystal of aluminum antimonide (AlSb) includes providing a growing environment with which to grow a crystal, growing a single crystal of AlSb in the growing environment which comprises hydrogen (H.sub.2) gas to reduce oxide formation and subsequent incorporation of oxygen impurities in the crystal, and adding a controlled amount of at least one impurity to the growing environment to effectively incorporate at least one dopant into the crystal. In another embodiment, a high energy radiation detector includes a single high-purity crystal of AlSb, a supporting structure for the crystal, and logic for interpreting signals obtained from the crystal which is operable as a radiation detector at a temperature of about 25.degree. C. In one embodiment, a high-purity single crystal of AlSb includes AlSb and at least one dopant selected from a group consisting of selenium (Se), tellurium (Te), and tin (Sn).

  19. Performance evaluation of ZnO–CuO hetero junction solid state room temperature ethanol sensor

    SciTech Connect (OSTI)

    Yu, Ming-Ru; Suyambrakasam, Gobalakrishnan; Wu, Ren-Jang; Department of Nanotechnology, School of Interdisciplinary Courses, Noorul Islam Centre for Higher Education, Noorul Islam University, Kumaracoil 629180, Tamil Nadu ; Chavali, Murthy; Department of Applied Chemistry, Providence University, 200 Chungchi Road, Shalu, Taichung Hsien 433, Taiwan, R.O.C

    2012-07-15

    Graphical abstract: Sensor response (resistance) curves of time were changed from 150 ppm to 250 ppm alcohol concentration of ZnO–CuO 1:1. The response and recovery times were measured to be 62 and 83 s, respectively. The sensing material ZnO–CuO is a high potential alcohol sensor which provides a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature. Highlights: ► The main advantages of the ethanol sensor are as followings. ► Novel materials ZnO–CuO ethanol sensor. ► The optimized ZnO–CuO hetero contact system. ► A good sensor response and room working temperature (save energy). -- Abstract: A semiconductor ethanol sensor was developed using ZnO–CuO and its performance was evaluated at room temperature. Hetero-junction sensor was made of ZnO–CuO nanoparticles for sensing alcohol at room temperature. Nanoparticles were prepared by hydrothermal method and optimized with different weight ratios. Sensor characteristics were linear for the concentration range of 150–250 ppm. Composite materials of ZnO–CuO were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR) and high-resolution transmission electron microscopy (HR-TEM). ZnO–CuO (1:1) material showed maximum sensor response (S = R{sub air}/R{sub alcohol}) of 3.32 ± 0.1 toward 200 ppm of alcohol vapor at room temperature. The response and recovery times were measured to be 62 and 83 s, respectively. The linearity R{sup 2} of the sensor response was 0.9026. The sensing materials ZnO–CuO (1:1) provide a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature.

  20. Room temperature spin transport in undoped (110) GaAs/AlGaAs quantum wells

    SciTech Connect (OSTI)

    Yokota, Nobuhide Aoshima, Yohei; Ikeda, Kazuhiro; Kawaguchi, Hitoshi

    2014-02-17

    We are reporting on our first observation of a micrometer-order electron spin transport in a (110) GaAs/AlGaAs multiple quantum well (QW) at room temperature using a space- and time-resolved Kerr rotation technique. A 37-μm transport was observed within an electron spin lifetime of 1.2 ns at room temperature when using an in-plane electric field of 1.75 kV/cm. The spatio-temporal profiles of electron spins were well reproduced by the spin drift-diffusion equations coupled with the Poisson equation, supporting the validity of the measurement. The results suggest that (110) QWs are useful as a spin transport layer for semiconductor spintronic devices operating at room temperature.

  1. Ferromagnetism at room temperature in Cr-doped anodic titanium dioxide nanotubes

    SciTech Connect (OSTI)

    Liao, Yulong E-mail: hwzhang@uestc.edu.cn; Zhang, Huaiwu E-mail: hwzhang@uestc.edu.cn; Li, Jie; Yu, Guoliang; Zhong, Zhiyong; Bai, Feiming; Jia, Lijun; Zhang, Shihong; Zhong, Peng

    2014-05-07

    This study reports the room-temperature ferromagnetism in Cr-doped TiO{sub 2} nanotubes (NTs) synthesized via the electrochemical method followed by a novel Cr-doping process. Scanning electron microscopy and transmission electron microscopy showed that the TiO{sub 2} NTs were highly ordered with length up to 26 ?m, outer diameter about 110 nm, and inner diameter about 100 nm. X-ray diffraction results indicated there were no magnetic contaminations of metallic Cr clusters or any other phases except anatase TiO{sub 2}. The Cr-doped TiO{sub 2} NTs were further annealed in oxygen, air and argon, and room-temperature ferromagnetism was observed in all Cr-doped samples. Moreover, saturation magnetizations and coercivities of the Cr-doped under various annealing atmosphere were further analyzed, and results indicate that oxygen content played a critical role in the room-temperature ferromagnetism.

  2. Room-temperature spin-polarized organic light-emitting diodes with a single ferromagnetic electrode

    SciTech Connect (OSTI)

    Ding, Baofu, E-mail: b.ding@ecu.edu.au; Alameh, Kamal, E-mail: k.alameh@ecu.edu.au [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup WA 6027 Australia (Australia); Song, Qunliang [Institute for Clean Energy and Advanced Materials, Southwest University, Chongqing 400715 (China)

    2014-05-19

    In this paper, we demonstrate the concept of a room-temperature spin-polarized organic light-emitting diode (Spin-OLED) structure based on (i) the deposition of an ultra-thin p-type organic buffer layer on the surface of the ferromagnetic electrode of the Spin-OLED and (ii) the use of oxygen plasma treatment to modify the surface of that electrode. Experimental results demonstrate that the brightness of the developed Spin-OLED can be increased by 110% and that a magneto-electroluminescence of 12% can be attained for a 150?mT in-plane magnetic field, at room temperature. This is attributed to enhanced hole and room-temperature spin-polarized injection from the ferromagnetic electrode, respectively.

  3. Shot-noise-limited magnetometer with sub-picotesla sensitivity at room temperature

    SciTech Connect (OSTI)

    Lucivero, Vito Giovanni; Anielski, Pawel; Gawlik, Wojciech; Mitchell, Morgan W.

    2014-11-15

    We report a photon shot-noise-limited (SNL) optical magnetometer based on amplitude modulated optical rotation using a room-temperature {sup 85}Rb vapor in a cell with anti-relaxation coating. The instrument achieves a room-temperature sensitivity of 70 fT/?(Hz) at 7.6 ?T. Experimental scaling of noise with optical power, in agreement with theoretical predictions, confirms the SNL behaviour from 5 ?T to 75??T. The combination of best-in-class sensitivity and SNL operation makes the system a promising candidate for application of squeezed light to a state-of-the-art atomic sensor.

  4. PNA-peptide Assembly in a 3D DNA Nanocage at Room Temperature

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

    PNA-peptide Assembly in a 3D DNA Nanocage at Room Temperature Authors: Flory, J.D., Shinde, S., Lin, S., Liu, Y., Yan, H., Ghirlanda, G., and Fromme, P. Title: PNA-peptide Assembly in a 3D DNA Nanocage at Room Temperature Source: J. Am. Chem. Soc. Year: 2013 Volume: 135 (18) Pages: 6985-6993 ABSTRACT: Proteins and peptides fold into dynamic structures that access a broad functional landscape, however, designing artificial polypeptide systems is still a great challenge. Conversely, DNA

  5. Quantum confinement of zero-dimensional hybrid organic-inorganic polaritons at room temperature

    SciTech Connect (OSTI)

    Nguyen, H. S.; Lafosse, X.; Amo, A.; Bouchoule, S.; Bloch, J.; Abdel-Baki, K.; Lauret, J.-S.; Deleporte, E.

    2014-02-24

    We report on the quantum confinement of zero-dimensional polaritons in perovskite-based microcavity at room temperature. Photoluminescence of discrete polaritonic states is observed for polaritons localized in symmetric sphere-like defects which are spontaneously nucleated on the top dielectric Bragg mirror. The linewidth of these confined states is found much sharper (almost one order of magnitude) than that of photonic modes in the perovskite planar microcavity. Our results show the possibility to study organic-inorganic cavity polaritons in confined microstructure and suggest a fabrication method to realize integrated polaritonic devices operating at room temperature.

  6. Lithium ion conducting ionic electrolytes

    DOE Patents [OSTI]

    Angell, C. Austen; Xu, Kang; Liu, Changle

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors.

  7. Lithium ion conducting ionic electrolytes

    DOE Patents [OSTI]

    Angell, C.A.; Xu, K.; Liu, C.

    1996-01-16

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100 C or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors. 4 figs.

  8. Novel Fission-Product Separation Based on Room Temperature Ionic Liquids

    SciTech Connect (OSTI)

    Luo, Huimin; Dai, Sheng; Bonnesen, Peter V.; Buchanan, A.C.; Rogers, Robin D.; Holbrey, John D.; Hussey, Charles L.

    2005-01-19

    This presentation was given at the DOE Office of Science-Environmental Management Science Program (EMSP) High-Level Waste Workshop held on January 19-20, 2005 at the Savannah River Site.

  9. High resolution InSb quantum well ballistic nanosensors for room temperature applications

    SciTech Connect (OSTI)

    Gilbertson, Adam; Cohen, L. F.; Lambert, C. J.; Solin, S. A.

    2013-12-04

    We report the room temperature operation of a quasi-ballistic InSb quantum well Hall sensor that exhibits a high frequency sensitivity of 560nT/?Hz at 20uA bias current. The device utilizes a partitioned buffer layer design that suppresses leakage currents through the mesa floor and can sustain large current densities.

  10. Instantaneous radioiodination of rose bengal at room temperature and a cold-kit therefor. [DOE patent application

    DOE Patents [OSTI]

    O'Brien, H. Jr.; Hupf, H.B.; Wanek, P.M.

    The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free /sup 125/I/sup -/ is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

  11. Room temperature broadband terahertz gains in graphene heterostructures based on inter-layer radiative transitions

    SciTech Connect (OSTI)

    Tang, Linlong; Du, Jinglei; Shi, Haofei Wei, Dongshan; Du, Chunlei

    2014-10-15

    We exploit inter-layer radiative transitions to provide gains to amplify terahertz waves in graphene heterostructures. This is achieved by properly doping graphene sheets and aligning their energy bands so that the processes of stimulated emissions can overwhelm absorptions. We derive an expression for the gain estimation and show the gain is insensitive to temperature variation. Moreover, the gain is broadband and can be strong enough to compensate the free carrier loss, indicating graphene based room temperature terahertz lasers are feasible.

  12. Room-temperature elastic constants of Sc and ScD[sub 0. 18

    SciTech Connect (OSTI)

    Leisure, R.G. ); Schwarz, R.B.; Migliori, A.; Lei, M. )

    1993-07-01

    The complete set of elastic constants for Sc and ScD[sub 0.18] has been measured at room temperature. The results show that the addition of hydrogen to this rare-earth metal has a qualitatively different effect than the addition of hydrogen to transition metals such as palladium, vanadium, niobium, and tantalum. In the case of Sc all five elastic constants increase with the addition of hydrogen. The bulk modulus for ScD[sub 0.18] is 9.5% higher than that for Sc. The Debye temperature computed from the room-temperature elastic constants is 355 K for Sc and 371 K for ScD[sub 0.18].

  13. Iron-aluminum alloys having high room-temperature and method for making same

    DOE Patents [OSTI]

    Sikka, Vinod K.; McKamey, Claudette G.

    1993-01-01

    Iron-aluminum alloys having selectable room-temperature ductilities of greater than 20%, high resistance to oxidation and sulfidation, resistant pitting and corrosion in aqueous solutions, and possessing relatively high yield and ultimate tensile strengths are described. These alloys comprise 8 to 9.5% aluminum, up to 7% chromium, up to 4% molybdenum, up to 0.05% carbon, up to 0.5% of a carbide former such as zirconium, up to 0.1 yttrium, and the balance iron. These alloys in wrought form are annealed at a selected temperature in the range of 700.degree. C. to about 1100.degree. C. for providing the alloys with selected room-temperature ductilities in the range of 20 to about 29%.

  14. Giant electrocaloric effect in asymmetric ferroelectric tunnel junctions at room temperature

    SciTech Connect (OSTI)

    Liu, Yang Infante, Ingrid C.; Dkhil, Brahim; Lou, Xiaojie

    2014-02-24

    Room-temperature electrocaloric properties of Pt/BaTiO{sub 3}/SrRuO{sub 3} ferroelectric tunnel junctions (FTJs) are studied by using a multiscale thermodynamic model. It is found that there is a divergence in the adiabatic temperature change ΔT for the two opposite polarization orientations. This difference under a typical writing voltage of 3 V can reach over 1 K as the barrier thickness decreases. Thanks to the ultrahigh external stimulus, a giant electrocaloric effect (1.53 K/V) with ΔT being over 4.5 K can be achieved at room temperature, which demonstrates the perspective of FTJs as a promising solid-state refrigeration.

  15. Cu-Cu direct bonding achieved by surface method at room temperature

    SciTech Connect (OSTI)

    Utsumi, Jun [Advanced Technology Research Center, Mitsubishi Heavy Industries, Ltd., 1-8-1 Sachiura, Kanazawa-ku, Yokohama 236-8515 (Japan); Ichiyanagi, Yuko, E-mail: yuko@ynu.ac.jp [Department of Physics, Graduate School of Engineering, Yokohama National University, Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan)

    2014-02-20

    The metal bonding is a key technology in the processes for the microelectromechanical systems (MEMS) devices and the semiconductor devices to improve functionality and higher density integration. Strong adhesion between surfaces at the atomic level is crucial; however, it is difficult to achieve close bonding in such a system. Cu films were deposited on Si substrates by vacuum deposition, and then, two Cu films were bonded directly by means of surface activated bonding (SAB) at room temperature. The two Cu films, with the surface roughness Ra about 1.3nm, were bonded by using SAB at room temperature, however, the bonding strength was very weak in this method. In order to improve the bonding strength between the Cu films, samples were annealed at low temperatures, between 323 and 473 K, in air. As the result, the Cu-Cu bonding strength was 10 times higher than that of the original samples without annealing.

  16. Realization of ground-state artificial skyrmion lattices at room temperature

    SciTech Connect (OSTI)

    Gilbert, Dustin A.; Maranville, Brian B.; Balk, Andrew L.; Kirby, Brian J.; Fischer, Peter; Pierce, Daniel T.; Unguris, John; Borchers, Julie A.; Liu, Kai

    2015-10-08

    We report that the topological nature of magnetic skyrmions leads to extraordinary properties that provide new insights into fundamental problems of magnetism and exciting potentials for novel magnetic technologies. Prerequisite are systems exhibiting skyrmion lattices at ambient conditions, which have been elusive so far. We demonstrate the realization of artificial Bloch skyrmion lattices over extended areas in their ground state at room temperature by patterning asymmetric magnetic nanodots with controlled circularity on an underlayer with perpendicular magnetic anisotropy (PMA). Polarity is controlled by a tailored magnetic field sequence and demonstrated in magnetometry measurements. The vortex structure is imprinted from the dots into the interfacial region of the underlayer via suppression of the PMA by a critical ion-irradiation step. In conclusion, the imprinted skyrmion lattices are identified directly with polarized neutron reflectometry and confirmed by magnetoresistance measurements. Our results demonstrate an exciting platform to explore room-temperature ground-state skyrmion lattices.

  17. Realization of ground-state artificial skyrmion lattices at room temperature

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

    Gilbert, Dustin A.; Maranville, Brian B.; Balk, Andrew L.; Kirby, Brian J.; Fischer, Peter; Pierce, Daniel T.; Unguris, John; Borchers, Julie A.; Liu, Kai

    2015-10-08

    We report that the topological nature of magnetic skyrmions leads to extraordinary properties that provide new insights into fundamental problems of magnetism and exciting potentials for novel magnetic technologies. Prerequisite are systems exhibiting skyrmion lattices at ambient conditions, which have been elusive so far. We demonstrate the realization of artificial Bloch skyrmion lattices over extended areas in their ground state at room temperature by patterning asymmetric magnetic nanodots with controlled circularity on an underlayer with perpendicular magnetic anisotropy (PMA). Polarity is controlled by a tailored magnetic field sequence and demonstrated in magnetometry measurements. The vortex structure is imprinted from themore » dots into the interfacial region of the underlayer via suppression of the PMA by a critical ion-irradiation step. In conclusion, the imprinted skyrmion lattices are identified directly with polarized neutron reflectometry and confirmed by magnetoresistance measurements. Our results demonstrate an exciting platform to explore room-temperature ground-state skyrmion lattices.« less

  18. Observation of optical spin injection into Ge-based structures at room temperature

    SciTech Connect (OSTI)

    Yasutake, Yuhsuke; Hayashi, Shuhei; Fukatsu, Susumu; Yaguchi, Hiroyuki

    2013-06-17

    Non-zero spin polarization induced by optical orientation was clearly observed at room temperature in a Ge/Ge{sub 0.8}Si{sub 0.2} quantum well grown on Ge and a Ge layer grown on Si by molecular beam epitaxy, whereas it was absent in bulk Ge. This occurred because indirect-gap photoluminescence (PL), which can obscure the spin-polarization information carried by the direct-gap PL, was quenched by unintentional growth-related defects in the epitaxial layers. Such interpretation was confirmed by applying time gating that effectively removed the indirect-gap PL characterized by a slower rise time, which allowed us to demonstrate the existence of room-temperature spin polarization in bulk Ge.

  19. Research on cw electron accelerators using room-temperature rf structures: Annual report

    SciTech Connect (OSTI)

    Not Available

    1986-08-15

    This joint NBS-Los Alamos project of ''Research on CW Electron Accelerators Using Room-Temperature RF Structures'' began seven years ago with the goal of developing a technology base for cw electron accelerators. In this report we describe our progress during FY 1986 and present our plans for completion of the project. First, however, it is appropriate to review the past contributions of the project, describe its status, and indicate its future benefits.

  20. Method of Production of Pure Hydrogen Near Room Temperature From Ultra High

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

    Capacity Hydride Materials - Energy Innovation Portal Hydrogen and Fuel Cell Hydrogen and Fuel Cell Energy Storage Energy Storage Advanced Materials Advanced Materials Find More Like This Return to Search Method of Production of Pure Hydrogen Near Room Temperature From Ultra High Capacity Hydride Materials Ames Laboratory Contact AMES About This Technology Technology Marketing Summary This is a cost-effective method for the production of pure hydrogen gas from ultra high capacity hydride

  1. Use of ionic liquids as coordination ligands for organometallic catalysts

    DOE Patents [OSTI]

    Li, Zaiwei; Tang, Yongchun; Cheng; Jihong

    2009-11-10

    Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.

  2. Scanning tunneling microscopy reveals LiMnAs is a room temperature anti-ferromagnetic semiconductor

    SciTech Connect (OSTI)

    Wijnheijmer, A. P.; Koenraad, P. M.; Marti, X.; Holy, V.; Cukr, M.; Novak, V.; Jungwirth, T.

    2012-03-12

    We performed scanning tunneling microscopy and spectroscopy on a LiMnAs(001) thin film epitaxially grown on an InAs(001) substrate by molecular beam epitaxy. While the in situ cleavage exposed only the InAs(110) non-polar planes, the cleavage continued into the LiMnAs thin layer across several facets. We combined both topography and current mappings to confirm that the facets correspond to LiMnAs. By spectroscopy we show that LiMnAs has a band gap. The band gap evidenced in this study, combined with the known Neel temperature well above room temperature, confirms that LiMnAs is a promising candidate for exploring the concepts of high temperature semiconductor spintronics based on antiferromagnets.

  3. Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond

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

    King, Jonathan P.; Jeong, Keunhong; Vassiliou, Christophoros C.; Shin, Chang S.; Page, Ralph H.; Avalos, Claudia E.; Wang, Hai-Jing; Pines, Alexander

    2015-12-07

    Low detection sensitivity stemming from the weak polarization of nuclear spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance nuclear spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of 13C nuclear spins observed via high-field magnetic resonance. The technique harnesses the high optically induced spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic nuclear polarization. We observe bulk nuclear spin polarization of 6%, an enhancement of ~170,000 over thermal equilibrium. The signal ofmore » the hyperpolarized spins was detected in situ with a standard nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. In conclusion, hyperpolarization via optical pumping/dynamic nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for nuclear magnetic resonance of solids and liquids under ambient conditions.« less

  4. Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond

    SciTech Connect (OSTI)

    King, Jonathan P.; Jeong, Keunhong; Vassiliou, Christophoros C.; Shin, Chang S.; Page, Ralph H.; Avalos, Claudia E.; Wang, Hai-Jing; Pines, Alexander

    2015-12-07

    Low detection sensitivity stemming from the weak polarization of nuclear spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance nuclear spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of 13C nuclear spins observed via high-field magnetic resonance. The technique harnesses the high optically induced spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic nuclear polarization. We observe bulk nuclear spin polarization of 6%, an enhancement of ~170,000 over thermal equilibrium. The signal of the hyperpolarized spins was detected in situ with a standard nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. In conclusion, hyperpolarization via optical pumping/dynamic nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for nuclear magnetic resonance of solids and liquids under ambient conditions.

  5. Stable room-temperature ferromagnetic phase at the FeRh(100) surface

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

    Pressacco, Federico; Uhlir, Vojtech; Gatti, Matteo; Bendounan, Azzedine; Fullerton, Eric E.; Sirotti, Fausto

    2016-03-03

    Interfaces and low dimensionality are sources of strong modifications of electronic, structural, and magnetic properties of materials. FeRh alloys are an excellent example because of the first-order phase transition taking place at ~400 K from an antiferromagnetic phase at room temperature to a high temperature ferromagnetic one. It is accompanied by a resistance change and volume expansion of about 1%. We have investigated the electronic and magnetic properties of FeRh(100) epitaxially grown on MgO by combining spectroscopies characterized by different probing depths, namely X-ray magnetic circular dichroism and photoelectron spectroscopy. Furthermore, we find that the symmetry breaking induced at themore » Rh-terminated surface stabilizes a surface ferromagnetic layer involving five planes of Fe and Rh atoms in the nominally antiferromagnetic phase at room temperature. First-principles calculations provide a microscopic description of the structural relaxation and the electron spin-density distribution that support the experimental findings.« less

  6. Detection of pico-Tesla magnetic fields using magneto-electric sensors at room temperature

    SciTech Connect (OSTI)

    Zhai Junyi; Xing Zengping; Dong Shuxiang; Li Jiefang; Viehland, D. [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2006-02-06

    The measurement of low-frequency (10{sup -2}-10{sup 3} Hz) minute magnetic field variations (10{sup -12} Tesla) at room temperature in a passive mode of operation would be critically enabling for deployable neurological signal interfacing and magnetic anomaly detection applications. However, there is presently no magnetic field sensor capable of meeting all of these requirements. Here, we present new bimorph and push-pull magneto-electric laminate composites, which incorporate a charge compensation mechanism (or bridge) that dramatically enhances noise rejection, enabling achievement of such requirements.

  7. A comparison of hydrogen and mercury embrittlement in monel at room temperature

    SciTech Connect (OSTI)

    Taylor, L.B.; Price, C.E.

    1986-01-01

    Slow strain rate tensile tests were performed on annealed and cold drawn Monel 400 and Monel R405 at room temperature in air, mercury, and electrolyte hydrogen. Hydrogen and mercury caused embrittlement with the fractures having the same specific features. Crack initiation was largely intergranular but an increasing proportion of transgranular cracking occurred subsequently, especially in the presence of hydrogen and for monel R405. It is believed that the decreased cohesive strength and enhanced shear models of embrittlement apply to the intergranular and transgranular crack modes respectively.

  8. Microstructure development during equal channel angular drawing of Al at room temperature

    SciTech Connect (OSTI)

    Chakkingal, U.; Suriadi, A.B.; Thomson, P.F.

    1998-08-11

    In this study 3004 aluminum alloy can-stock remelt (composition 99.9% Al) was subjected to Equal Channel Angular Drawing (ECAD) at room temperature. Tests were conducted to an applied true strain of 2.95. Mechanical properties like tensile strength, ductility at fracture, and microhardness were measured. The development of the substructure was studied using optical and transmission electron microscopy. Subgrain sizes and their angular misorientations were measured as a function of the applied strain. In general, a substructure that consists of cells and subgrains was seen to evolve, as is expected for the case of high SFE fcc metals.

  9. Transparent conductive Al-doped ZnO thin films grown at room temperature

    SciTech Connect (OSTI)

    Wang Yuping; Lu Jianguo; Bie Xun; Gong Li; Li Xiang; Song Da; Zhao Xuyang; Ye Wenyi; Ye Zhizhen

    2011-05-15

    Aluminum-doped ZnO (ZnO:Al, AZO) thin films were prepared on glass substrates by dc reactive magnetron sputtering from a Zn-Al alloy target at room temperature. The effects of the Ar-to-O{sub 2} partial pressure ratios on the structural, electrical, and optical properties of AZO films were studied in detail. AZO films grown using 100:4 to 100:8 Ar-to-O{sub 2} ratio result in acceptable quality films with c-axis orientated crystals, uniform grains, 10{sup -3} {Omega} cm resistivity, greater than 10{sup 20} cm{sup -3} electron concentration, and high transmittance, 90%, in the visible region. The lowest resistivity of 4.11x10{sup -3} {Omega} cm was obtained under the Ar-to-O{sub 2} partial pressure ratio of 100:4. A relatively strong UV emission at {approx}3.26 eV was observed in the room-temperature photoluminescence spectrum. X-ray photoelectron spectroscopy analysis confirmed that Al was introduced into ZnO and substitutes for Zn and doped the film n-type.

  10. Behavior of tritium permeation induced by water corrosion of alpha iron around room temperature

    SciTech Connect (OSTI)

    Otsuka, T.; Hashizume, K.

    2015-03-15

    Tritium (T) permeation leakage to surroundings is a great safety concern in fission and fusion reactor systems. T permeation potentially occurs from T contaminated water through cooling tubes or storage tank made of metals which dissolve some T evolved by water corrosion. In order to understand behaviors of hydrogen uptake and permeation in pure α-iron (αFe) during water corrosion around room temperature, hydrogen permeation experiments for an αFe membrane have been conducted by means of tritium tracer techniques. The present study suggests that hydrogen produced by water corrosion of αFe is trapped in product oxide layers to delay hydrogen uptake in αFe for a moment. However, the oxide layers do not work as a sufficient barrier for hydrogen uptake. Some of hydrogen dissolved in αFe normally diffuses and permeates through the bulk in the early stage of permeation. In a later stage, hydrogen permeation could be apparently stopped by the disappearance of concentration difference of tritium. Hydrogen partial pressure at the water/αFe interface could be ranged from 0.7 to 9.5 kPa around room temperature.

  11. Room-temperature amorphous alloy field-effect transistor exhibiting particle and wave electronic transport

    SciTech Connect (OSTI)

    Fukuhara, M.; Kawarada, H.

    2015-02-28

    The realization of room-temperature macroscopic field effect transistors (FETs) will lead to new epoch-making possibilities for electronic applications. The I{sub d}-V{sub g} characteristics of the millimeter-sized aluminum-oxide amorphous alloy (Ni{sub 0.36}Nb{sub 0.24}Zr{sub 0.40}){sub 90}H{sub 10} FETs were measured at a gate-drain bias voltage of 060??V in nonmagnetic conditions and under a magnetic fields at room temperature. Application of dc voltages to the gate electrode resulted in the transistor exhibiting one-electron Coulomb oscillation with a period of 0.28?mV, Fabry-Perot interference with a period of 2.35??V under nonmagnetic conditions, and a Fano effect with a period of 0.26?mV for Vg and 0.2?T under a magnetic field. The realization of a low-energy controllable device made from millimeter-sized Ni-Nb-Zr-H amorphous alloy throws new light on cluster electronics.

  12. Non-magnetic organic/inorganic spin injector at room temperature

    SciTech Connect (OSTI)

    Mathew, Shinto P.; Mondal, Prakash Chandra; Naaman, Ron; Moshe, Hagay; Mastai, Yitzhak

    2014-12-15

    Spin injection into solid-state devices is commonly performed by use of ferromagnetic metal electrodes. Here, we present a spin injector design without permanent magnet; rather, the spin selectivity is determined by a chiral tunneling barrier. The chiral tunneling barrier is composed of an ultrathin Al{sub 2}O{sub 3} layer that is deposited on top of a chiral self-assembled monolayer (SAM), which consists of cysteine or oligopeptide molecules. The experimentally observed magnetoresistance can be up to 20% at room temperature, and it displays an uncommon asymmetric curve as a function of the applied magnetic field. These findings show that the spin injector transmits only one spin orientation, independent of external magnetic field. The sign of the magnetoresistance depends on the handedness of the molecules in the SAM, which act as a spin filter, and the magnitude of the magnetoresistance depends only weakly on temperature.

  13. Investigation of room temperature ferromagnetic nanoparticles of Gd5Si4

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

    Hadimani, R. L.; Gupta, S.; Harstad, S. M.; Pecharsky, V. K.; Jiles, D. C.

    2015-07-06

    Gd5(SixGe1-x)4 compounds undergo first-order phase transitions close to room temperature when x ~ = 0.5, which are accompanied by extreme changes of properties. We report the fabrication of the nanoparticles of one of the parent compounds-Gd5Si4-using high-energy ball milling. Crystal structure, microstructure, and magnetic properties have been investigated. Particles agglomerate at long milling times, and the particles that are milled >20 min lose crystallinity and no longer undergo magnetic phase transition close to 340 K, which is present in a bulk material. The samples milled for >20 min exhibit a slightly increased coercivity. As a result, magnetization at a highmore » temperature of 275K decreases with the increase in the milling time.« less

  14. Iron-aluminum alloys having high room-temperature and method for making same

    DOE Patents [OSTI]

    Sikka, V.K.; McKamey, C.G.

    1993-08-24

    A wrought and annealed iron-aluminum alloy is described consisting essentially of 8 to 9.5% aluminum, an effective amount of chromium sufficient to promote resistance to aqueous corrosion of the alloy, and an alloying constituent selected from the group of elements consisting of an effective amount of molybdenum sufficient to promote solution hardening of the alloy and resistance of the alloy to pitting when exposed to solutions containing chloride, up to about 0.05% carbon with up to about 0.5% of a carbide former which combines with the carbon to form carbides for controlling grain growth at elevated temperatures, and mixtures thereof, and the balance iron, wherein said alloy has a single disordered [alpha] phase crystal structure, is substantially non-susceptible to hydrogen embrittlement, and has a room-temperature ductility of greater than 20%.

  15. Room-temperature near-infrared silicon carbide nanocrystalline emitters based on optically aligned spin defects

    SciTech Connect (OSTI)

    Muzha, A.; Fuchs, F.; Simin, D.; Astakhov, G. V.; Tarakina, N. V.; Trupke, M.; Soltamov, V. A.; Mokhov, E. N.; Baranov, P. G.; Dyakonov, V.; and others

    2014-12-15

    Bulk silicon carbide (SiC) is a very promising material system for bio-applications and quantum sensing. However, its optical activity lies beyond the near infrared spectral window for in-vivo imaging and fiber communications due to a large forbidden energy gap. Here, we report the fabrication of SiC nanocrystals and isolation of different nanocrystal fractions ranged from 600?nm down to 60?nm in size. The structural analysis reveals further fragmentation of the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline quality, separated by amorphization areas. We use neutron irradiation to create silicon vacancies, demonstrating near infrared photoluminescence. Finally, we detect room-temperature spin resonances of these silicon vacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use them not only as in-vivo luminescent markers but also as magnetic field and temperature sensors, allowing for monitoring various physical, chemical, and biological processes.

  16. Method for stabilizing low-level mixed wastes at room temperature

    DOE Patents [OSTI]

    Wagh, A.S.; Singh, D.

    1997-07-08

    A method to stabilize solid and liquid waste at room temperature is provided comprising combining solid waste with a starter oxide to obtain a powder, contacting the powder with an acid solution to create a slurry, said acid solution containing the liquid waste, shaping the now-mixed slurry into a predetermined form, and allowing the now-formed slurry to set. The invention also provides for a method to encapsulate and stabilize waste containing cesium comprising combining the waste with Zr(OH){sub 4} to create a solid-phase mixture, mixing phosphoric acid with the solid-phase mixture to create a slurry, subjecting the slurry to pressure; and allowing the now pressurized slurry to set. Lastly, the invention provides for a method to stabilize liquid waste, comprising supplying a powder containing magnesium, sodium and phosphate in predetermined proportions, mixing said powder with the liquid waste, such as tritium, and allowing the resulting slurry to set. 4 figs.

  17. Blue photoluminescence enhancement in laser-irradiated 6H-SiC at room temperature

    SciTech Connect (OSTI)

    Wu, Yan; Ji, Lingfei Lin, Zhenyuan; Jiang, Yijian; Zhai, Tianrui

    2014-01-27

    Blue photoluminescence (PL) of 6H-SiC irradiated by an ultraviolet laser can be observed at room temperature in dark condition. PL spectra with Gaussian fitting curve of the irradiated SiC show that blue luminescence band (?440?nm) is more pronounced than other bands. The blue PL enhancement is the combined result of the improved shallow N-donor energy level and the unique surface state with Si nanocrystals and graphene/Si composite due to the effect of photon energy input by the short-wavelength laser irradiation. The study can provide a promising route towards the preparation of well-controlled blue photoluminescence material for light-emitting devices.

  18. Method for stabilizing low-level mixed wastes at room temperature

    DOE Patents [OSTI]

    Wagh, Arun S. (Joliet, IL); Singh, Dileep (Westmont, IL)

    1997-01-01

    A method to stabilize solid and liquid waste at room temperature is provided comprising combining solid waste with a starter oxide to obtain a powder, contacting the powder with an acid solution to create a slurry, said acid solution containing the liquid waste, shaping the now-mixed slurry into a predetermined form, and allowing the now-formed slurry to set. The invention also provides for a method to encapsulate and stabilize waste containing cesium comprising combining the waste with Zr(OH).sub.4 to create a solid-phase mixture, mixing phosphoric acid with the solid-phase mixture to create a slurry, subjecting the slurry to pressure; and allowing the now pressurized slurry to set. Lastly, the invention provides for a method to stabilize liquid waste, comprising supplying a powder containing magnesium, sodium and phosphate in predetermined proportions, mixing said powder with the liquid waste, such as tritium, and allowing the resulting slurry to set.

  19. Comparative study of the embrittlement of Monel 400 at room temperature by hydrogen and by mercury

    SciTech Connect (OSTI)

    Price, C.E.; Fredell, R.S.

    1986-05-01

    Slow strain rate tensile tests were performed at room temperature on Monel 400 specimens of grain sizes 35 to 500 microns, in the environments of air, mercury, and electrolytically generated hydrogen. Specimens of grain size 250 microns were tested at a range of strain rates in the three environments. It was found that cracks initiated easiest in hydrogen but propagated easiest in mercury; consequently the embrittlement was usually more severe in mercury. The embrittlement decreased with increasing strain rate, and with increasing grain size in hydrogen. Embrittlement in mercury was maximum at intermediate grain sizes. A fracture sequence of intergranular to transgranular to microvoid coalescence was common. The intergranular and transgranular fractures are interpreted in terms of the reduced cohesive stress and enhanced shear models of embrittlement, respectively. 52 references.

  20. Experimental Observation of the Inverse Spin Hall Effect at Room Temperature

    SciTech Connect (OSTI)

    Liu, Baoli; Shi, Junren; Wang, Wenxin; Zhao, Hongming; Li, Dafang; Zhang, Shoucheng; Xue, Qikun; Chen, Dongmin; /Beijing, Inst. Phys.

    2010-03-16

    We observe the inverse spin Hall effect in a two-dimensional electron gas confined in Al-GaAs/InGaAs quantum wells. Specifically, they find that an inhomogeneous spin density induced by the optical injection gives rise to an electric current transverse to both the spin polarization and its gradient. The spin Hall conductivity can be inferred from such a measurement through the Einstein relation and the onsager relation, and is found to have the order of magnitude of 0.5(e{sup 2}/h). The observation is made at the room temperature and in samples with macroscopic sizes, suggesting that the inverse spin Hall effects is a robust macroscopic transport phenomenon.

  1. Sessile dislocations by reactions in NiAl severely deformed at room temperature

    SciTech Connect (OSTI)

    Geist, D.; Gammer, C.; Rentenberger, C.; Karnthaler, H. P.

    2015-02-05

    B2 ordered NiAl is known for its poor room temperature (RT) ductility; failure occurs in a brittle like manner even in ductile single crystals deforming by single slip. In the present study NiAl was severely deformed at RT using the method of high pressure torsion (HPT) enabling the hitherto impossible investigation of multiple slip deformation. Methods of transmission electron microscopy were used to analyze the dislocations formed by the plastic deformation showing that as expected dislocations with Burgers vector a(100) carry the plasticity during HPT deformation at RT. In addition, we observe that they often form a(110) dislocations by dislocation reactions; the a(110) dislocations are considered to be sessile based on calculations found in the literature. It is therefore concluded that the frequently encountered 3D dislocation networks containing sessile a(110) dislocations are pinned and lead to deformation-induced embrittlement. In spite of the severe deformation, the chemical order remains unchanged.

  2. On the magnetic field signal radiated by an atmospheric pressure room temperature plasma jet

    SciTech Connect (OSTI)

    Wu, S.; Huang, Q.; Wang, Z.; Lu, X. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2013-01-28

    In this paper, the magnetic field signal radiated from an atmospheric pressure room temperature plasma plume is measured. It's found that the magnetic field signal has similar waveform as the current carried by the plasma plume. By calibration of the magnetic field signal, the plasma plume current is obtained by measuring the magnetic field signal radiated by the plasma plume. In addition, it is found that, when gas flow modes changes from laminar regime to turbulence regime, the magnetic field signal waveforms appears different, it changes from a smooth curve to a curve with multiple spikes. Furthermore, it is confirmed that the plasma plume generated by a single electrode (without ground electrode) plasma jet device carries higher current than that with ground electrode.

  3. Environmental effect on room-temperature ductility of isothermally forged TiAl-base alloys

    SciTech Connect (OSTI)

    Nakamura, Morihiko; Hashimoto, Kenki (National Research Inst. for Metals, Tokyo (Japan)); Itoh, Naoyuki (Nippon Steel Corp., Chiba (Japan)); Tsujimoto, Tokuzo (Ibaraki Univ. (Japan). Faculty of Engineering); Suzuki, Toshiyuki (Kougakuin Univ., Tokyo (Japan))

    1994-02-01

    Isothermally forged TiAl-base alloy (Al-rich, Mn-containing, and Cr-containing TiAl) were heat-treated in various conditions, and equiaxed grain structures consisting of [gamma] and [alpha][sub 2] or [beta] phases were obtained. The heat-treated alloys were tensile tested in vacuum and air at room temperature, and the environmental effect on tensile elongation was studied. The ductility of the alloys consisting of equiaxed [gamma] grains and a large amount of [alpha][sub 2] grains was not largely affecting by laboratory air, and a decrease in the amount of [alpha][sub 2] grains resulted in a large reduction of ductility in air. The [beta] phase in the Cr-containing alloy improved the ductility in vacuum, but it resulted in a large reduction of ductility in air.

  4. Direct Observation of Room-Temperature Polar Ordering in Colloidal GeTe Nanocrystals

    SciTech Connect (OSTI)

    Polking, Mark J.; Zheng, Haimei; Urban, Jeffrey J.; Milliron, Delia J.; Chan, Emory; Caldwell, Marissa A.; Raoux, Simone; Kisielowski, Christian F.; Ager III, Joel W.; Ramesh, Ramamoorthy; Alivisatos, A.P.

    2009-12-07

    Ferroelectrics and other materials that exhibit spontaneous polar ordering have demonstrated immense promise for applications ranging from non-volatile memories to microelectromechanical systems. However, experimental evidence of polar ordering and effective synthetic strategies for accessing these materials are lacking for low-dimensional nanomaterials. Here, we demonstrate the synthesis of size-controlled nanocrystals of the polar material germanium telluride (GeTe) using colloidal chemistry and provide the first direct evidence of room-temperature polar ordering in nanocrystals less than 5 nm in size using aberration-corrected transmission electron microscopy. Synchrotron x-ray diffraction and Raman studies demonstrate a sizeable polar distortion and a reversible size-dependent polar phase transition in these nanocrystals. The stability of polar ordering in solution-processible nanomaterials suggests an economical avenue to Tbit/in2-density non-volatile memory devices and other applications.

  5. Effects of high temperature surface oxides on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

    SciTech Connect (OSTI)

    Buchanan, R.A.; Perrin, R.L.

    1996-09-01

    Studies were conducted to determine the effects of high-temperature surface oxides, produced during thermomechanical processing, heat treatment (750 {degrees}C in air, one hour) or simulated in-service-type oxidation (1000{degrees}C in air, 24 hours) on the room-temperature aqueous-corrosion and environmental-embrittlement characteristics of iron aluminides. Materials evaluated included the Fe{sub 3}Al-based iron aluminides, FA-84, FA-129, FAL and FAL-Mo, a FeAl-based iron aluminide, FA-385, and a disordered low-aluminum Fe-Al alloy, FAPY. Tests were performed in a mild acid-chloride solution to simulate aggressive atmospheric corrosion. Cyclic-anodic-polarization tests were employed to evaluate resistances to localized aqueous corrosion. The high-temperature oxide surfaces consistently produced detrimental results relative to mechanically or chemically cleaned surfaces. Specifically, the pitting corrosion resistances were much lower for the as-processed and 750{degrees} C surfaces, relative to the cleaned surfaces, for FA-84, FA-129, FAL-Mo, FA-385 and FAPY. Furthermore, the pitting corrosion resistances were much lower for the 1000{degrees}C surfaces, relative to cleaned surfaces, for FA-129, FAL and FAL-Mo.

  6. SRNL PHASE II SHELF LIFE STUDIES - SERIES 1 ROOM TEMPERATURE AND HIGH RELATIVE HUMIDITY

    SciTech Connect (OSTI)

    Mickalonis, J.; Duffey, J.

    2012-09-12

    The Savannah River National Laboratory (SRNL) Phase II, Series 1 shelf-life corrosion testing for the Department of Energy Standard 3013 container is presented and discussed in terms of the localized corrosion behavior of Type 304 stainless steel in contact with moist plutonium oxide and chloride salt mixtures and the potential impact to the 3013 inner container. This testing was designed to address the influence of temperature, salt composition, initial salt moisture, residual stress and type of oxide/salt contact on the relative humidity inside a 3013 container and the initiation and propagation of localized corrosion, especially stress corrosion cracking. The integrated plan is being conducted by Los Alamos National Laboratory and SRNL. SRNL is responsible for conducting a corrosion study in small scale vessels containing plutonium oxide and chloride salts under conditions of humidity, temperature and oxide/salt compositions both within the limits of 3013 storage conditions as well as beyond the 3013 storage requirements to identify margins for minimizing the initiation of stress corrosion cracking. These worst case conditions provide data that bound the material packaged in 3013 containers. Phase I of this testing was completed in 2010. The Phase II, Series 1 testing was performed to verify previous results from Phase I testing and extend our understanding about the initiation of stress corrosion cracking and pitting that occur in 304L under conditions of room temperature, high humidity, and a specific plutonium oxide/salt chemistry. These results will aid in bounding the safe storage conditions of plutonium oxides in 3013 containers. A substantial change in the testing was the addition of the capability to monitor relative humidity during test exposure. The results show that under conditions of high initial moisture ({approx}0.5 wt%) and room temperature stress corrosion cracking occurred in 304L teardrop coupons in contact with the oxide/salt mixture at times

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

    SciTech Connect (OSTI)

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

    2009-09-01

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

  8. New insights into designing metallacarborane based room temperature hydrogen storage media

    SciTech Connect (OSTI)

    Bora, Pankaj Lochan; Singh, Abhishek K.

    2013-10-28

    Metallacarboranes are promising towards realizing room temperature hydrogen storage media because of the presence of both transition metal and carbon atoms. In metallacarborane clusters, the transition metal adsorbs hydrogen molecules and carbon can link these clusters to form metal organic framework, which can serve as a complete storage medium. Using first principles density functional calculations, we chalk out the underlying principles of designing an efficient metallacarborane based hydrogen storage media. The storage capacity of hydrogen depends upon the number of available transition metal d-orbitals, number of carbons, and dopant atoms in the cluster. These factors control the amount of charge transfer from metal to the cluster, thereby affecting the number of adsorbed hydrogen molecules. This correlation between the charge transfer and storage capacity is general in nature, and can be applied to designing efficient hydrogen storage systems. Following this strategy, a search for the best metallacarborane was carried out in which Sc based monocarborane was found to be the most promising H{sub 2} sorbent material with a 9 wt.% of reversible storage at ambient pressure and temperature.

  9. Spreading of lithium on a stainless steel surface at room temperature

    SciTech Connect (OSTI)

    Skinner, C. H.; Capece, A. M.; Roszell, J. P.; Koel, B. E.

    2016-01-01

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. The spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 mu m/day under ultrahigh vacuum conditions. Separate experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (E-des = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (E-des = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding. (C) 2015 Elsevier B.V. All rights reserved.

  10. Spreading of lithium on a stainless steel surface at room temperature

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

    Skinner, C. H.; Capece, A. M.; Roszell, J. P.; Koel, B. E.

    2016-01-01

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices and liquid lithium plasma facing components are under consideration for future machines. A key factor in the performance of liquid lithium components is the wetting by lithium of its container. We have observed the surface spreading of lithium from a mm-scale particle to adjacent stainless steel surfaces using a scanning Auger microprobe that has elemental discrimination. The spreading of lithium occurred at room temperature (when lithium is a solid) from one location at a speed of 0.62 mu m/day under ultrahigh vacuum conditions. Separatemore » experiments using temperature programmed desorption (TPD) investigated bonding energetics between monolayer-scale films of lithium and stainless steel. While multilayer lithium desorption from stainless steel begins to occur just above 500 K (E-des = 1.54 eV), sub-monolayer Li desorption occurred in a TPD peak at 942 K (E-des = 2.52 eV) indicating more energetically favorable lithium-stainless steel bonding (in the absence of an oxidation layer) than lithium lithium bonding. (C) 2015 Elsevier B.V. All rights reserved.« less

  11. Room-temperature nonlinear transport phenomena in low-dimensional Ni-Nb-Zr-H glassy alloys and its device

    SciTech Connect (OSTI)

    Fukuhara, Mikio; Yoshida, Hajime

    2014-05-15

    We report the room-temperature switching and Coulomb blockade effects in threeterminal glassy alloy field effect transistor (GAFET), using the millimeter sized glassy alloy. By applying dc and ac voltages to a gate electrode, GAFET can be switched from a metallic conducting state to an insulating state with Coulomb oscillation at a period of 14 ?V at room temperature. The transistor showed the three-dimensional Coulomb diamond structure. The fabrication of a low-energy controllable device throws a new light on cluster electronics without wiring.

  12. Synthesis and characterization of new class of ionic liquids containing phenolate anion

    SciTech Connect (OSTI)

    Lethesh, Kallidanthiyil Chellappan; Wilfred, Cecilia Devi; Taha, M. F.; Thanabalan, M.

    2014-10-24

    In these manuscript novel ionic liquids containing a new class of 'phenolate' anions was synthesized and characterized. 1-methylmidazole with different alkyl chains such as butyl, hexyl and octyl groups was used as the cationic part. All the ionic liquids were obtained as liquids at room temperature. The synthesized ionic liquids were characterized using {sup 1}H NMR and {sup 13}C NMR spectroscopy. The thermal stability of the ionic liquids was studied using thermo gravimetric analysis (TGA). The effect of temperature on the density and viscosity of the ionic liquids were studied over a temperature range from 293.15 K to 373.15K at atmospheric pressure. From the experimental values of density, the molecular volume, standard molar entropy and the lattice energy of the ionic liquids were calculated.

  13. Computational Study of Ionic Liquids | netl.doe.gov

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

    Computational Study of Ionic Liquids Computational Study of Ionic Liquids Illuminates Detailed CO2 Interactions Ionic liquids (ILs), which can be thought of as salts that are molten at room temperature, are being studied for use as part of CO2 adsorption and/or separation technologies. These applications depend on having strong interactions between the CO2 and the ions of the IL. In order for significant advances to occur in this area of research, the interaction between the CO2 and each IL must

  14. Sessile dislocations by reactions in NiAl severely deformed at room temperature

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

    Geist, D.; Gammer, C.; Rentenberger, C.; Karnthaler, H. P.

    2015-02-05

    B2 ordered NiAl is known for its poor room temperature (RT) ductility; failure occurs in a brittle like manner even in ductile single crystals deforming by single slip. In the present study NiAl was severely deformed at RT using the method of high pressure torsion (HPT) enabling the hitherto impossible investigation of multiple slip deformation. Methods of transmission electron microscopy were used to analyze the dislocations formed by the plastic deformation showing that as expected dislocations with Burgers vector a(100) carry the plasticity during HPT deformation at RT. In addition, we observe that they often form a(110) dislocations by dislocationmore » reactions; the a(110) dislocations are considered to be sessile based on calculations found in the literature. It is therefore concluded that the frequently encountered 3D dislocation networks containing sessile a(110) dislocations are pinned and lead to deformation-induced embrittlement. In spite of the severe deformation, the chemical order remains unchanged.« less

  15. Thermodynamic Analysis Of Pure And Impurity Doped Pentaerythritol Tetranitrate Crystals Grown At Room Temperature

    SciTech Connect (OSTI)

    Pitchimani, R; Zheng, W; Simon, S; Hope-Weeks, L; Burnham, A K; Weeks, B L

    2006-05-25

    Pentaerythritol tetranitrate (PETN) powders are used to initiate other explosives. During long-term storage, changes in powder properties can cause changes in the initiation performance. Changes in the morphology and surface area of aging powders are observed due to sublimation and growth of PETN crystals through coarsening mechanisms, (e.g. Ostwald ripening, sintering, etc.). In order to alleviate the sublimation of PETN crystals under service conditions, stabilization methods such as thermal cycling and doping with certain impurities during or after the crystallization of PETN have been proposed. In this report we present our work on the effect of impurities on the morphology and activation energy of the PETN crystals. The pure and impurity doped crystals of PETN were grown from supersaturated acetone solution by solvent evaporation technique at room temperature. The difference in the morphology of the impurity-doped PETN crystal compared to pure crystal was examined by optical microscopy. The changes in the activation energies and the evaporation rates are determined by thermogravimetric (TGA) analyses. Our activation energies of evaporation agree with earlier reported enthalpies of vaporization. The morphology and activation energy of PETN crystals doped with Ca, Na, and Fe cations are similar to that for pure PETN crystal, whereas the Zn-ion-doped PETN crystals have different morphology and decreased activation energy.

  16. Calculation of room temperature conductivity and mobility in tin-based topological insulator nanoribbons

    SciTech Connect (OSTI)

    Vandenberghe, William G. Fischetti, Massimo V.

    2014-11-07

    Monolayers of tin (stannanane) functionalized with halogens have been shown to be topological insulators. Using density functional theory (DFT), we study the electronic properties and room-temperature transport of nanoribbons of iodine-functionalized stannanane showing that the overlap integral between the wavefunctions associated to edge-states at opposite ends of the ribbons decreases with increasing width of the ribbons. Obtaining the phonon spectra and the deformation potentials also from DFT, we calculate the conductivity of the ribbons using the Kubo-Greenwood formalism and show that their mobility is limited by inter-edge phonon backscattering. We show that wide stannanane ribbons have a mobility exceeding 10{sup 6} cm{sup 2}/Vs. Contrary to ordinary semiconductors, two-dimensional topological insulators exhibit a high conductivity at low charge density, decreasing with increasing carrier density. Furthermore, the conductivity of iodine-functionalized stannanane ribbons can be modulated over a range of three orders of magnitude, thus rendering this material extremely interesting for classical computing applications.

  17. Molecular and crystal structure of n-hexyloxybenzoic anhydride at low and room temperatures

    SciTech Connect (OSTI)

    Konstantinov, I. I.; Churakov, A. V.; Kuz'mina, L. G.

    2010-09-15

    The crystal and molecular structures of n-hexyloxybenzoic anhydride, C{sub 6}H{sub 13}-O-C{sub 6}H{sub 4}-C(O)-O-C(O)-C{sub 6}H{sub 4}-C{sub 6}H{sub 13}, at low (120 K) and room (296 K) temperatures have been investigated. The molecule has an asymmetric bent structure. The dihedral angle between the benzene ring planes is 48.5 deg. The aliphatic chain on one side of the molecule has a transoid orientation with respect to the 'internal' C4 atom of the closest benzene ring, whereas the aliphatic chain on the other side has a cissoid orientation with respect to the analogous C(4A) atom. The crystal packing does not exhibit any pronounced separation of the crystal space into closely packed aromatic or loosely packed aliphatic regions. No weak directional interactions are observed in the packing; this fact explains the absence of liquid-crystal properties for this compound.

  18. Room temperature alcohol sensing by oxygen vacancy controlled TiO{sub 2} nanotube array

    SciTech Connect (OSTI)

    Hazra, A.; Dutta, K.; Bhowmik, B.; Bhattacharyya, P.; Chattopadhyay, P. P.

    2014-08-25

    Oxygen vacancy (OV) controlled TiO{sub 2} nanotubes, having diameters of 5070?nm and lengths of 200250?nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH{sub 4}F and ethylene glycol with selective H{sub 2}O content. The structural evolution of TiO{sub 2} nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO{sub 2} nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO{sub 2} nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

  19. Radiation defect dynamics in Si at room temperature studied by pulsed ion beams

    SciTech Connect (OSTI)

    Wallace, J. B.; Myers, M. T.; Charnvanichborikarn, S.; Bayu Aji, L. B.; Kucheyev, S. O.; Shao, L.

    2015-10-07

    The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length is revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ∼4–13 ms and a diffusion length of ∼15–50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.

  20. Synthesis of monodispersed CdSe nanocrystals in poly(styrene-alt-maleic anhydride) at room temperature

    SciTech Connect (OSTI)

    Liu, S.H.; Qian, X.F.; Yuan, J.Y.; Yin, J.; He, R.; Zhu, Z.K

    2003-07-14

    Nanocomposite of CdSe/poly(styrene-alt-maleic anhydride) (PSM) was successfully prepared via an in situ reaction process at room temperature and ambient pressure. Transmission electron microscopy (TEM) analysis revealed that CdSe nanoparticles with a small size and narrow size distribution were obtained. The obtained nanocomposite was also characterized by FT-IR, XRD, ultraviolet-visible, and fluorescence spectroscopy.

  1. Multilayered YSZ/GZO films with greatly enhanced ionic conduction for low temperature solid oxide fuel cells

    SciTech Connect (OSTI)

    Li, Bin; Zhang, Jiaming; Kaspar, Tiffany C.; Shutthanandan, V.; Ewing, Rodney C.; Lian, Jie

    2013-01-01

    Strain confinement in heterostructured films significantly affects ionic conductivity of the electrolytes for solid oxide fuel cells based on a multi-layered design strategy. Nearly ideal tensile strain can be achieved by a dedicated manipulation of the lattice mismatch between adjacent layers and fine control of the layer thicknesses to minimize the formation of dislocations and thus to achieve optimized ionic conduction. This strategy was demonstrated by a model system of multilayered 8 mol%Y2O3 stabilized ZrO2 (YSZ) with Gd2Zr2O7 (GZO) films, which were epitaxially grown on Al2O3 (0001) substrates by pulsed laser deposition (PLD) with the {111} planes of YSZ/GZO along the Al2O3 [0 1 ?1 0] direction. The tensile strain (3%) resulting from the lattice mismatch can be confined in individual YSZ layers with the formation of a coherent, dislocation-free interface upon the manipulation of the layer thickness below a critical value, e.g., down to 5 nm. The strained heterostructure displays a two order-of-magnitude increase in oxide-ion conductivity as compared with bulk YSZ, and a high ionic conductivity of 0.01 S cm?1 at 475 C can be achieved, five times greater than that of Gd-doped ceria/zirconia. The approach of strain confinement by fine control of lattice mismatch and layer thickness represents a promising strategy in developing advanced electrolytes enabling the miniaturization of solid-state ionic devices that can be operated at low temperatures below 500 C.

  2. Optical diode effect at spin-wave excitations in the room-temperature multiferroic BiFeO3.

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

    Kezsmarki, I.; Nagel, U.; Bordacs, S.; Fishman, Randy Scott; Lee, Jun Hee; Yi, Hee Taek; Cheong, Sang-Wook; Room, T.

    2015-09-15

    The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO3 over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. Our findingsmore » are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.« less

  3. Symmetries and multiferroic properties of novel room-temperature magnetoelectrics: Lead iron tantalate – lead zirconate titanate (PFT/PZT)

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

    Sanchez, Dilsom A.; Ortega, N.; Kumar, Ashok; Roque-Malherbe, R.; Polanco, R.; Scott, J. F.; Katiyar, Ram S.

    2011-12-01

    Mixing 60-70% lead zirconate titanate with 40-30% lead iron tantalate produces a single-phase, low-loss, room-temperature multiferroic with magnetoelectric coupling: (PbZr₀.₅₃Ti₀.₄₇O₃) (1-x)- (PbFe₀.₅Ta₀.₅O₃)x. The present study combines x-ray scattering, magnetic and polarization hysteresis in both phases, plus a second-order dielectric divergence (to epsilon = 6000 at 475 K for 0.4 PFT; to 4000 at 520 K for 0.3 PFT) for an unambiguous assignment as a C2v-C4v (Pmm2-P4mm) transition. The material exhibits square saturated magnetic hysteresis loops with 0.1 emu/g at 295 K and saturation polarization Pr = 25 μC/cm², which actually increases (to 40 μC/cm²) in the high-T tetragonal phase, representingmore » an exciting new room temperature oxide multiferroic to compete with BiFeO₃. Additional transitions at high temperatures (cubic at T>1300 K) and low temperatures (rhombohedral or monoclinic at T<250 K) are found. These are the lowest-loss room-temperature multiferroics known, which is a great advantage for magnetoelectric devices.« less

  4. Room temperature nonlinear magnetoelectric effect in lead-free and Nb-doped AlFeO{sub 3} compositions

    SciTech Connect (OSTI)

    Ctica, Luiz F.; Santos, Guilherme M.; Santos, Ivair A.; Freitas, Valdirlei F.; Coelho, Adelino A.; Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar S.; Garcia, Ducinei; Eiras, Jos A.

    2015-02-14

    It is still a challenging problem to obtain technologically useful materials displaying strong magnetoelectric coupling at room temperature. In the search for new effects and materials to achieve this kind of coupling, a nonlinear magnetoelectric effect was proposed in the magnetically disordered relaxor ferroelectric materials. In this context, the aluminum iron oxide (AlFeO{sub 3}), a room temperature ferroelectric relaxor and magnetic spin glass compound, emerges as an attractive lead-free magnetoelectric material along with nonlinear magnetoelectric effects. In this work, static, dynamic, and temperature dependent ferroic and magnetoelectric properties in lead-free AlFeO{sub 3} and 2 at.?% Nb-doped AlFeO{sub 3} multiferroic magnetoelectric compositions are studied. Pyroelectric and magnetic measurements show changes in ferroelectric and magnetic states close to each other (?200?K). The magnetoelectric coefficient behavior as a function of H{sub bias} suggests a room temperature nonlinear magnetoelectric coupling in both single-phase and Nb-doped AlFeO{sub 3}-based ceramic compositions.

  5. Induced spin-polarization of EuS at room temperature in Ni/EuS multilayers

    SciTech Connect (OSTI)

    Poulopoulos, P.; Goschew, A.; Straub, A.; Fumagalli, P.; Kapaklis, V.; Wolff, M.; Delimitis, A.; Wilhelm, F.; Rogalev, A.; Pappas, S. D.

    2014-03-17

    Ni/EuS multilayers with excellent multilayer sequencing are deposited via e-beam evaporation on the native oxide of Si(100) wafers at 4 × 10{sup −9} millibars. The samples have very small surface and interface roughness and show sharp interfaces. Ni layers are nanocrystalline 4–8 nm thick and EuS layers are 2–4 nm thick and are either amorphous or nanocrystalline. Unlike for Co/EuS multilayers, all Eu ions are in divalent (ferromagnetic) state. We show a direct antiferromagnetic coupling between EuS and Ni layers. At room temperature, the EuS layers are spin-polarized due to the proximity of Ni. Therefore, Ni/EuS is a candidate for room-temperature spintronics applications.

  6. Flexible micro-supercapacitor based on in-situ assembled graphene on metal template at room temperature

    SciTech Connect (OSTI)

    Wu, ZK; Lin, ZY; Li, LY; Song, B; Moon, KS; Bai, SL; Wong, CP

    2014-11-01

    Graphene based micro-supercapacitors (MSCs) have been extensively studied in recent years; however, few of them report room temperature fabricating methods for flexible MSC. Here we developed a convenient procedure based on simultaneous self-assembly and reduction of graphene oxide (GO) on Cu/Au interdigit at room temperature. The as-produced MSC shows a specific areal capacitance of 0.95 mF cm(-2) and maintains 98.3% after 11,000 cycles of charge and discharge. Extremely small relaxation time constants of 1.9 ms in aqueous electrolyte and 4.8 ms in gelled electrolyte are achieved. Also the device shows great flexibility and retains 93.5% of the capacitance after 5000 times of bending and twisting tests. (C) 2014 Elsevier Ltd. All rights reserved.

  7. Wide-bandgap high-mobility ZnO thin-film transistors produced at room temperature

    SciTech Connect (OSTI)

    Fortunato, Elvira M.C.; Barquinha, Pedro M.C.; Pimentel, Ana C.M.B.G.; Goncalves, Alexandra M.F.; Marques, Antonio J.S.; Martins, Rodrigo F.P.; Pereira, Luis M.N.

    2004-09-27

    We report high-performance ZnO thin-film transistor (ZnO-TFT) fabricated by rf magnetron sputtering at room temperature with a bottom gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 19 V, a saturation mobility of 27 cm{sup 2}/V s, a gate voltage swing of 1.39 V/decade and an on/off ratio of 3x10{sup 5}. The ZnO-TFT presents an average optical transmission (including the glass substrate) of 80% in the visible part of the spectrum. The combination of transparency, high mobility, and room-temperature processing makes the ZnO-TFT a very promising low-cost optoelectronic device for the next generation of invisible and flexible electronics.

  8. Homogeneous and inhomogeneous sources of optical transition broadening in room temperature CdSe/ZnS nanocrystal quantum dots

    SciTech Connect (OSTI)

    Wolf, M.; Berezovsky, J.

    2014-10-06

    We perform photoluminescence excitation measurements on individual CdSe/ZnS nanocrystal quantum dots (NCQDs) at room temperature to study optical transition energies and broadening. The observed features in the spectra are identified and compared to calculated transition energies using an effective mass model. The observed broadening is attributed to phonon broadening, spectral diffusion, and size and shape inhomogeneity. The former two contribute to the broadening transitions in individual QDs, while the latter contributes to the QD-to-QD variation. We find that phonon broadening is often not the dominant contribution to transition line widths, even at room temperature, and that broadening does not necessarily increase with transition energy. This may be explained by differing magnitude of spectral diffusion for different quantum-confined states.

  9. Ionic Liquid Pretreatment Technologies

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

    volatile organic solvents used in processes * Often associated with Green Chemistry. ... - properties Anion determines: - chemistry - functionality Room Temperature, Molten ...

  10. Low and Room Temperature X-ray Structures of Protein Kinase A Ternary Complexes Shed New Light on Its Activity

    SciTech Connect (OSTI)

    Fisher, Zoe; Hanson, Leif; Kovalevsky, Andrey; Langan, Paul

    2012-01-01

    Posttranslational protein phosphorylation by protein kinase A (PKA) is a ubiquitous signaling mechanism which regulates many cellular processes. A low temperature X-ray structure of the PKA catalytic subunit (PKAc) ternary complex with ATP and a 20-residue peptidic inhibitor (IP20) at the physiological Mg2+ concentration of < 0.5mM revealed a single metal ion in the active site. The lack of a second metal in the low-temperature LT-PKAc-MgATP-IP20 renders the and phosphoryl groups of ATP to be very flexibile, with high thermal B-factors. Thus, the second metal is crucial for tight positioning of the terminal phosphoryl for transfer to a substrate, as demonstrated by comparison of the former structure with LT-PKAc- Mg2ATP-IP20 complex. In addition to the kinase activity, PKAc is also able to slowly catalyze the hydrolysis of ATP using a water molecule as a substrate. We found that at room temperature under X-ray irradiation ATP can be readily and completely hydrolyzed into ATP and a free phosphate ion in the crystals of the ternary complex LT-PKAc- Mg2ATP-IP20. The cleavage of ATP may be aided by X-ray-born free hydroxyl radicals, a very reactive chemical species, that move quickly through the crystal at room temperature. The phosphate anion is clearly visible in the electron density maps; it remains in the active site, but slides about 2 from its position in ATP toward Ala21 of IP20 that mimics the phosphorylation site. The phosphate, thus, pushes the peptidic inhibitor away from the product ADP, while resulting in dramatic conformational changes of IP20 terminal residues 24 and 25. X-ray structures of PKAc in complex with non-hydrolyzable ATP analog, AMPPNP, at both room and low temperatures demonstrated no temperature effects on the conformation and position of IP20.

  11. FINAL REPORT: Room Temperature Hydrogen Storage in Nano-Confined Liquids

    SciTech Connect (OSTI)

    VAJO, JOHN

    2014-06-12

    DOE continues to seek solid-state hydrogen storage materials with hydrogen densities of ≥6 wt% and ≥50 g/L that can deliver hydrogen and be recharged at room temperature and moderate pressures enabling widespread use in transportation applications. Meanwhile, development including vehicle engineering and delivery infrastructure continues for compressed-gas hydrogen storage systems. Although compressed gas storage avoids the materials-based issues associated with solid-state storage, achieving acceptable volumetric densities has been a persistent challenge. This project examined the possibility of developing storage materials that would be compatible with compressed gas storage technology based on enhanced hydrogen solubility in nano-confined liquid solvents. These materials would store hydrogen in molecular form eliminating many limitations of current solid-state materials while increasing the volumetric capacity of compressed hydrogen storage vessels. Experimental methods were developed to study hydrogen solubility in nano-confined liquids. These methods included 1) fabrication of composites comprised of volatile liquid solvents for hydrogen confined within the nano-sized pore volume of nanoporous scaffolds and 2) measuring the hydrogen uptake capacity of these composites without altering the composite composition. The hydrogen storage capacities of these nano-confined solvent/scaffold composites were compared with bulk solvents and with empty scaffolds. The solvents and scaffolds were varied to optimize the enhancement in hydrogen solubility that accompanies confinement of the solvent. In addition, computational simulations were performed to study the molecular-scale structure of liquid solvent when confined within an atomically realistic nano-sized pore of a model scaffold. Confined solvent was compared with similar simulations of bulk solvent. The results from the simulations were used to formulate a mechanism for the enhanced solubility and to guide the

  12. Photochemical preparation of CdS hollow microspheres at room temperature and their use in visible-light photocatalysis

    SciTech Connect (OSTI)

    Huang Yuying; Sun Fengqiang; Wu Tianxing; Wu Qingsong; Huang Zhong; Su Heng; Zhang Zihe

    2011-03-15

    CdS hollow microspheres have been successfully prepared by a photochemical preparation technology at room temperature, using polystyrene latex particles as templates, CdSO{sub 4} as cadmium source and Na{sub 2}S{sub 2}O{sub 3} as both sulphur source and photo-initiator. The process involved the deposition of CdS nanoparticles on the surface of polystyrene latex particles under the irradiation of an 8 W UV lamp and the subsequent removal of the latex particles by dispersing in dichloromethane. Photochemical reactions at the sphere/solution interface should be responsible for the formation of hollow spheres. The as-prepared products were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Such hollow spheres could be used in photocatalysis and showed high photocatalytic activities in photodegradation of methyl blue (MB) in the presence of H{sub 2}O{sub 2}. The method is green, simple, universal and can be extended to prepare other sulphide and oxide hollow spheres. -- Graphical abstract: Taking polystyrene spheres dispersed in a precursor solution as templates, CdS hollow microspheres composed of nanoparticles were successfully prepared via a new photochemical route at room temperature. Display Omitted Research highlights: {yields} Photochemical method was first employed to prepare hollow microspheres. {yields} CdS hollow spheres were first prepared at room temperature using latex spheres. {yields} The polystyrene spheres used as templates were not modified with special groups. {yields}The CdS hollow microspheres showed high visible-light photocatalytic activities.

  13. An electron microscopy study of dislocation structures in Mg single crystals compressed along [0 0 0 1] at room temperature

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

    Kumar, K. S.; Chisholm, Matthew F.; Geng, J.; Mishra, R. K.

    2016-01-09

    We compressed Mg single crystals along [0 0 0 1] at room temperature to various stress levels (40, 80, 120, 160 and 320 MPa) and the evolution of dislocation structure with stress increment was investigated by TEM slip is confirmed to be the dominant deformation mode; the predominance of edge dislocation debris lying along the <1 0more » $$\\bar{1}$$ 0> implies that screw dislocations are more mobile than their edge counterpart. The edge dislocation may dissociate into and dislocations, and the latter can extend further on the basal plane and bound a basal-stacking fault.« less

  14. Peculiarly strong room-temperature ferromagnetism from low Mn-doping in ZnO grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Zuo Zheng; Morshed, Muhammad; Liu Jianlin; Beyermann, W. P.; Zheng Jianguo; Xin Yan

    2013-03-15

    Strong room-temperature ferromagnetism is demonstrated in single crystalline Mn-doped ZnO thin films grown by molecular beam epitaxy. Very low Mn doping concentration is investigated, and the measured magnetic moment is much larger than what is expected for an isolated ion based on Hund's rules. The ferromagnetic behavior evolves with Mn concentration. Both magnetic anisotropy and anomalous Hall effect confirm the intrinsic nature of ferromagnetism. While the Mn dopant plays a crucial role, another entity in the system is needed to explain the observed large magnetic moments.

  15. Thin-film transistors based on p-type Cu{sub 2}O thin films produced at room temperature

    SciTech Connect (OSTI)

    Fortunato, Elvira; Figueiredo, Vitor; Barquinha, Pedro; Elamurugu, Elangovan; Goncalves, Goncalo; Martins, Rodrigo; Park, Sang-Hee Ko; Hwang, Chi-Sun

    2010-05-10

    Copper oxide (Cu{sub 2}O) thin films were used to produce bottom gate p-type transparent thin-film transistors (TFTs). Cu{sub 2}O was deposited by reactive rf magnetron sputtering at room temperature and the films exhibit a polycrystalline structure with a strongest orientation along (111) plane. The TFTs exhibit improved electrical performance such as a field-effect mobility of 3.9 cm{sup 2}/V s and an on/off ratio of 2x10{sup 2}.

  16. Room temperature strain rate sensitivity in precursor derived HfO{sub 2}/Si-C-N(O) ceramic nanocomposites

    SciTech Connect (OSTI)

    Sujith, Ravindran; Kumar, Ravi

    2014-01-15

    Investigation on the room temperature strain rate sensitivity using depth sensing nanoindentation is carried out on precursor derived HfO{sub 2}/Si-C-N(O) ceramic nanocomposite sintered using pulsed electric current sintering. Using constant load method the strain rate sensitivity values are estimated. Lower strain rate sensitivity of ? 3.7 10{sup ?3} is observed and the limited strain rate sensitivity of these ceramic nanocomposites is explained in terms of cluster model. It is concluded that presence of amorphous Si-C-N(O) clusters are responsible for the limited flowability in these ceramics.

  17. Duplex precipitates and their effects on the room-temperature fracture behaviour of a NiAl-strengthened ferritic alloy

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

    Sun, Zhiqian; Song, Gian; Ilavsky, Jan; Liaw, Peter K.

    2015-03-23

    Duplex precipitates are presented in a NiAl-strengthened ferritic alloy. They were characterized by the ultra-small angle X-ray scattering and transmission electron microscope. Fine cooling precipitates with the size of several to tens of nanometres harden the matrix considerably at room temperature. Cracks are likely to initiate from precipitates, and coalesce and propagate quickly through the matrix due to the excessive hardening effect of cooling precipitates, which lead to the premature fracture of NiAl-strengthened ferritic alloys.

  18. Near fifty percent sodium substituted lanthanum manganites—A potential magnetic refrigerant for room temperature applications

    SciTech Connect (OSTI)

    Sethulakshmi, N.; Anantharaman, M. R.; Al-Omari, I. A.; Suresh, K. G.

    2014-03-03

    Nearly half of lanthanum sites in lanthanum manganites were substituted with monovalent ion-sodium and the compound possessed distorted orthorhombic structure. Ferromagnetic ordering at 300 K and the magnetic isotherms at different temperature ranges were analyzed for estimating magnetic entropy variation. Magnetic entropy change of 1.5 J·kg{sup −1}·K{sup −1} was observed near 300 K. An appreciable magnetocaloric effect was also observed for a wide range of temperatures near 300 K for small magnetic field variation. Heat capacity was measured for temperatures lower than 300 K and the adiabatic temperature change increases with increase in temperature with a maximum of 0.62 K at 280 K.

  19. Infrared study on room-temperature atomic layer deposition of HfO{sub 2} using tetrakis(ethylmethylamino)hafnium and remote plasma-excited oxidizing agents

    SciTech Connect (OSTI)

    Kanomata, Kensaku [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan and Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Ohba, Hisashi; Pungboon Pansila, P.; Ahmmad, Bashir; Kubota, Shigeru; Hirahara, Kazuhiro; Hirose, Fumihiko, E-mail: fhirose@yz.yamagata-u.ac.jp [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan)

    2015-01-01

    Room-temperature atomic layer deposition (ALD) of HfO{sub 2} was examined using tetrakis (ethylmethylamino)hafnium (TEMAH) and remote plasma-excited water and oxygen. A growth rate of 0.26?nm/cycle at room temperature was achieved, and the TEMAH adsorption and its oxidization on HfO{sub 2} were investigated by multiple internal reflection infrared absorption spectroscopy. It was observed that saturated adsorption of TEMAH occurs at exposures of ?1??10{sup 5}?L (1 L?=?1??10{sup ?6} Torr s) at room temperature, and the use of remote plasma-excited water and oxygen vapor is effective in oxidizing the TEMAH molecules on the HfO{sub 2} surface, to produce OH sites. The infrared study suggested that HfOH plays a role as an adsorption site for TEMAH. The reaction mechanism of room temperature HfO{sub 2} ALD is discussed in this paper.

  20. Spin-Induced Polarizations and Nonreciprocal Directional Dichroism of the Room-Temperature Multiferroic BiFeO3

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

    Fishman, Randy Scott; Lee, Jun Hee; Bordacs, Sandor; Kezsmarki, Istvan; Nagel, Urmas; Room, Toomas

    2015-09-14

    A microscopic model for the room-temperature multiferroic BiFeO3 that includes two Dzyaloshinskii-Moriya interactions and single-ion anisotropy along the ferroelectric polarization predicts both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field. Due to simultaneously broken time-reversal and spatial-inversion symmetries, the absorption of light changes as the magnetic field or the direction of light propagation is reversed. We discuss three physical mechanisms that may contribute to this absorption asymmetry known as directional dichroism: the spin current, magnetostriction, and single-ion anisotropy. We conclude that the directional dichroism in BiFeO3 is dominated by the spin-current polarization andmore » is insensitive to the magnetostriction and easy-axis anisotropy. With three independent spin-current parameters, our model accurately describes the directional dichroism observed for magnetic field along [1, -1, 0]. Since some modes are almost transparent to light traveling in one direction but opaque for light traveling in the opposite direction, BiFeO3 can be used as a room-temperature optical diode at certain frequencies in the GHz to THz range. This work demonstrates that an analysis of the directional dichroism spectra based on an effective spin model supplemented by first-principles calculations can produce a quantitative microscopic theory of the magnetoelectric couplings in multiferroic materials.« less

  1. Initial proof-of-principle for near room temperature Xe and Kr separation from air with MOFs

    SciTech Connect (OSTI)

    Thallapally, Praveen K.; Strachan, Denis M.

    2012-06-06

    Materials were developed and tested in support of the U.S. Department of Energy, Office of Nuclear Energy, Fuel Cycle Technology Separations and Waste Forms Campaign. Specifically, materials are being developed for the removal of Xenon and krypton from gaseous products of nuclear fuel reprocessing unit operations. During FY 2012, Three Metal organic framework (MOF) structures were investigated in greater detail for the removal and storage of Xe and Kr from air at room temperature. Our breakthrough measurements on Nickel based MOF could capture and separate parts per million levels of Xe from Air (40 ppm Kr, 78% N2, 21% O2, 0.9% Ar, 0.03% CO2). Similarly, the selectivity can be changed from Xe > Kr to Xe < Kr simply by changing the temperature in another MOF. Also for the first time we estimated the cost of the metal organic frameworks in bulk.

  2. Investigation of room temperature ferromagnetic nanoparticles of Gd5Si4

    SciTech Connect (OSTI)

    Hadimani, R. L.; Gupta, S.; Harstad, S. M.; Pecharsky, V. K.; Jiles, D. C.

    2015-07-06

    Gd5(SixGe1-x)4 compounds undergo first-order phase transitions close to room temperature when x ~ = 0.5, which are accompanied by extreme changes of properties. We report the fabrication of the nanoparticles of one of the parent compounds-Gd5Si4-using high-energy ball milling. Crystal structure, microstructure, and magnetic properties have been investigated. Particles agglomerate at long milling times, and the particles that are milled >20 min lose crystallinity and no longer undergo magnetic phase transition close to 340 K, which is present in a bulk material. The samples milled for >20 min exhibit a slightly increased coercivity. As a result, magnetization at a high temperature of 275K decreases with the increase in the milling time.

  3. VOC and HAP recovery using ionic liquids

    SciTech Connect (OSTI)

    Michael R. Milota : Kaichang Li

    2007-05-29

    During the manufacture of wood composites, paper, and to a lesser extent, lumber, large amounts of volatile organic compounds (VOCs) such as terpenes, formaldehyde, and methanol are emitted to air. Some of these compounds are hazardous air pollutants (HAPs). The air pollutants produced in the forest products industry are difficult to manage because the concentrations are very low. Presently, regenerative thermal oxidizers (RTOs and RCOs) are commonly used for the destruction of VOCs and HAPs. RTOs consume large amounts of natural gas to heat air and moisture. The combustion of natural gas generates increased CO2 and NOx, which have negative implications for global warming and air quality. The aforementioned problems are addressed by an absorption system containing a room-temperature ionic liquid (RTIL) as an absorbent. RTILs are salts, but are in liquid states at room temperature. RTILs, an emerging technology, are receiving much attention as replacements for organic solvents in industrial processes with significant cost and environmental benefits. Some of these processes include organic synthesis, extraction, and metal deposition. RTILs would be excellent absorbents for exhausts from wood products facilities because of their unique properties: no measurable vapor pressure, high solubility of wide range of organic compounds, thermal stability to 200°C (almost 400°F), and immisciblity with water. Room temperature ionic liquids were tested as possible absorbents. Four were imidizolium-based and were eight phosphonium-based. The imidizolium-based ionic liquids proved to be unstable at the conditions tested and in the presence of water. The phosphonium-based ionic liquids were stable. Most were good absorbents; however, cleaning the contaminates from the ionic liquids was problematic. This was overcome with a higher temperature (120°C) than originally proposed and a very low pressure (1 kPa. Absorption trials were conducted with tetradecy

  4. Electrochemistry in neutral ambient-temperature ionic liquids. 1. Studies of iron (III), neodymium (III), and lithium(I)

    SciTech Connect (OSTI)

    Osteryoung, R.A.

    1985-01-01

    An ambient-temperature neutral ionic liquid composed of aluminum chloride and either N-1-butylpyridinium or 1-methyl-3-ethylimidazolium chloride, BuPyCl or ImCl, respectively, was employed in studies that take advantage of their unusual properties. These include an extended electrochemical window, readily controlled additions of excess chloride (base) or aluminum chloride (acid), and the fact that the physical properties of the neutral melt do not change about the 1:1 mole ratio of AlCl/sub 3/ to RCl. Li/sup +/ was found to be reducible in the neutral AlCl/sub 3/-ImCl melt, and its diffusion coefficient was found to be .00000086 sq cm/s. The stoichiometry of the complex formed between Nd(III) and Cl/sup +/ in the molten salt system was investigated by what is essentially an amperometric titration and was found to be NdC/sub 6/(3-). The structure of the Fe(III) chloro complex that exists in basic or acidic melts just slightly varying in composition from the neutral melt was also investigated; a constant value for the diffusion coefficient-viscosity product in both systems suggests no change in structure.

  5. One-step room temperature synthesis of very small ?-Fe{sub 2}O{sub 3} nanoparticles

    SciTech Connect (OSTI)

    Moscoso-Londoo, O.; Carrio, M.S.; Cosio-Castaeda, C.; Bilovol, V.; Snchez, R. Martnez; Lede, E.J.; Socolovsky, L.M.; Martnez-Garca, R.

    2013-09-01

    Graphical abstract: - Highlights: One-step synthesis of 3 nm maghemite nanoparticles is reported. Maghemite nanoparticles can be synthesized from a ferric solution. ?-Fe{sub 2}O{sub 3} NPs can be obtained if the precursor has Fe(III) in tetrahedral interstices. HR-TEM, Mssbauer, XAFS and magnetometry analysis proved the maghemite existence - Abstract: Very small maghemite nanoparticles (?3 nm) are obtained through a one-step synthesis at room temperature. The fast neutralization reaction of a ferric solution in a basic medium produces an intermediate phase, presumably two-line ferrihydrite, which in oxidizing conditions is transformed to maghemite nanoparticles. The synthesis of maghemite, as final product of the reaction, was characterized by High-Resolution Transmission Electron Microscopy (HR-TEM), X-ray Absorption Fine Structure (XAFS), Mssbauer spectroscopy, and magnetometry. The XAFS technique allowed the analysis of the crystallographic variations into maghemite nanoparticles as a result of modification in its surface/volume ratio. Mssbauer spectroscopy at low temperature (4.2 K) confirms the presence of Fe(III) in tetrahedral and octahedral interstices, in the stoichiometry corresponding to maghemite. The specific magnetization, M vs H (3 K and 300 K, up to 7 T) and temperature dependence of the magnetization (50 Oe by ZFC mode, 2 K ? T ? 300 K) indicate that maghemite nanoparticles of 3 nm are in superparamagnetic state with a blocking temperature close to 36 K.

  6. Supercapacitors Based on Metal Electrodes Prepared from Nanoparticle Mixtures at Room Temperature

    SciTech Connect (OSTI)

    Nakanishi, Hideyuki; Grzybowski, Bartosz A.

    2010-01-01

    Films comprising Au and Ag nanoparticles are transformed into porous metal electrodes by desorption of weak organic ligands followed by wet chemical etching of silver. Thus prepared electrodes provide the basis for supercapacitors whose specific capacitances approach 70 F/g. Cyclic voltammetry measurement yield rectangular I-V curves even at high scan rates, indicating that the supercapacitors have low internal resistance. Owing to this property, the supercapacitors have a high power density ~12 kW/kg, comparable with that of the state-of-the-art carbon-based devices. The entire assembly protocol does not require high-temperature processing or the use of organic binders.

  7. Short-wavelength interband cascade infrared photodetectors operating above room temperature

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

    Lotfi, Hossein; Li, Lu; Lei, Lin; Jiang, Yuchao; Yang, Rui Q.; Klem, John F.; Johnson, Matthew B.

    2016-01-13

    High temperature operation (250–340 K) of short-wavelength interband cascade infrared photodetectors (ICIPs) with InAs/GaSb/Al0.2In0.8Sb/GaSb superlattice absorbers has been demonstrated with a 50% cutoff wavelength of 2.9 μm at 300 K. Two ICIP structures, one with two and the other with three stages, were designed and grown to explore this multiple-stage architecture. At λ = 2.1 μm, the two- and three-stage ICIPs had Johnson-noise-limited detectivities of 5.1 × 109 and 5.8 ×109 cm Hz1/2/W, respectively, at 300 K. The better device performance of the three-stage ICIP over the two-stage ICIP confirmed the advantage of more stages for this cascade architecture. Furthermore,more » an Arrhenius activation energy of 450 meV is extracted for the bulk resistance-area product, which indicates the dominance of the diffusion current at these high temperatures.« less

  8. Photoluminescence emission at room temperature in zinc oxide nano-columns

    SciTech Connect (OSTI)

    Rocha, L.S.R.; Deus, R.C.; Foschini, C.R.; Simes, A.Z.

    2014-02-01

    Highlights: ZnO nanoparticles were obtained by microwave-hydrothermal method. X-ray diffraction reveals a hexagonal structure. Photoluminescence emission evidenced two absorption peaks, at around 480 nm and 590 nm wavelengths. - Abstract: Hydrothermal microwave method (HTMW) was used to synthesize crystalline zinc oxide (ZnO) nano-columns at the temperature of 120 C with a soaking time of 8 min. ZnO nano-columns were characterized by using X-ray analyses (XRD), infrared spectroscopy (FT-IR), thermogravimetric analyses (TG-DTA), field emission gun and transmission electron microscopy (FEG-SEM and TEM) and photoluminescence properties (PL). XRD results indicated that the ZnO nano-columns are free of any impurity phase and crystallize in the hexagonal structure. Typical FT-IR spectra for ZnO nano-columns presented well defined bands, indicating a substantial short-range order in the system. PL spectra consist of a broad band at 590 nm and narrow band at 480 nm corresponding to a near-band edge emission related to the recombination of excitons and level emission related to structural defects. These results show that the HTMW synthesis route is rapid, cost effective, and could be used as an alternative to obtain ZnO nano-columns in the temperature of 120 C for 8 min.

  9. Low voltage tunneling magnetoresistance in CuCrO{sub 2}-based semiconductor heterojunctions at room temperature

    SciTech Connect (OSTI)

    Li, X. R.; Han, M. J.; Shan, C.; Hu, Z. G. Zhu, Z. Q.; Chu, J. H.; Wu, J. D.

    2014-12-14

    CuCrO{sub 2}-based heterojunction diodes with rectifying characteristics have been fabricated by combining p-type Mg-doped CuCrO{sub 2} and n-type Al-doped ZnO. It was found that the current for the heterojunction in low bias voltage region is dominated by the trap-assisted tunneling mechanism. Positive magnetoresistance (MR) effect for the heterojunction can be observed at room temperature due to the tunneling-induced antiparallel spin polarization near the heterostructure interface. The MR effect becomes enhanced with the magnetic field, and shows the maximum at a bias voltage around 0.5 V. The phenomena indicate that the CuCrO{sub 2}-based heterojunction is a promising candidate for low-power semiconductor spintronic devices.

  10. Novel room-temperature-setting phosphate ceramics for stabilizing combustion products and low-level mixed wastes

    SciTech Connect (OSTI)

    Wagh, A.S.; Singh, D.

    1994-12-31

    Argonne National Laboratory, with support from the Office of Technology in the US Department of Energy (DOE), has developed a new process employing novel, chemically bonded ceramic materials to stabilize secondary waste streams. Such waste streams result from the thermal processes used to stabilize low-level, mixed wastes. The process will help the electric power industry treat its combustion and low-level mixed wastes. The ceramic materials are strong, dense, leach-resistant, and inexpensive to fabricate. The room-temperature-setting process allows stabilization of volatile components containing lead, mercury, cadmium, chromium, and nickel. The process also provides effective stabilization of fossil fuel combustion products. It is most suitable for treating fly and bottom ashes.

  11. Room temperature continuous wave InGaAsN quantum well vertical cavity lasers emitting at 1.3 um

    SciTech Connect (OSTI)

    CHOQUETTE,KENT D.; KLEM,JOHN F.; FISCHER,ARTHUR J.; SPAHN,OLGA B.; ALLERMAN,ANDREW A.; FRITZ,IAN J.; KURTZ,STEVEN R.; BREILAND,WILLIAM G.; SIEG,ROBERT M.; GEIB,KENT M.; SCOTT,J.W.; NAONE,R.L.

    2000-06-05

    Selectively oxidized vertical cavity lasers emitting at 1294 nm using InGaAsN quantum wells are reported for the first time which operate continuous wave at and above room temperature. The lasers employ two n-type Al{sub 0.94}Ga{sub 0.06}As/GaAs distributed Bragg reflectors each with a selectively oxidized current aperture adjacent to the optical cavity, and the top output mirror contains a tunnel junction to inject holes into the active region. Continuous wave single mode lasing is observed up to 55 C. These lasers exhibit the longest wavelength reported to date for vertical cavity surface emitting lasers grown on GaAs substrates.

  12. Room-temperature ferromagnetism in Co and Nb co-doped TiO{sub 2} nanoparticles

    SciTech Connect (OSTI)

    Hachisu, M.; Mori, K.; Hyodo, K.; Morimoto, S.; Yamazaki, T.; Ichiyanagi, Y.

    2015-02-27

    Co- and Nb-doped TiO{sub 2} nanoparticles encapsulated with amorphous SiO{sub 2} were synthesized by our novel preparation method. An anatase TiO{sub 2} single-phase structure was confirmed using X-ray diffraction. The particle size could be controlled to be about 5 nm. The composition of these nanoparticles was investigated by X-ray fluorescence analysis. X-ray absorption near-edge structure spectra showed that the Ti{sup 4+} and Co{sup 2+} states were dominant in our prepared samples. A reduction in the coordination number was also confirmed. The dependence of the electrical conductivity on the frequency was measured by an LCR meter, and the carrier concentration was determined. The magnetization curves for the nanoparticles indicated ferromagnetic behavior at room temperature. We concluded that the ferromagnetism originated in oxygen vacancies around the transition metal ions.

  13. Metallic transport and large anomalous Hall effect at room temperature in ferrimagnetic Mn{sub 4}N epitaxial thin film

    SciTech Connect (OSTI)

    Shen, Xi; Shigematsu, Kei; Chikamatsu, Akira Fukumura, Tomoteru; Hirose, Yasushi; Hasegawa, Tetsuya

    2014-08-18

    We report the electrical transport properties of ferrimagnetic Mn{sub 4}N (001) epitaxial thin films grown by pulsed laser deposition on MgO (001) substrates. The Mn{sub 4}N thin films were tetragonally distorted with a ratio of out-of-plane to in-plane lattice constants of 0.987 and showed perpendicular magnetic anisotropy with an effective magnetic anisotropy constant of 0.16 MJ/m{sup 3}, which is comparable with that of a recently reported molecular-beam-epitaxy-grown film. The thin films exhibited metallic transport with a room temperature resistivity of 125 μΩ cm in addition to a large anomalous Hall effect with a Hall angle tangent of 0.023.

  14. Non-adiabatic ab initio molecular dynamics of supersonic beam epitaxy of silicon carbide at room temperature

    SciTech Connect (OSTI)

    Taioli, Simone; Garberoglio, Giovanni; Simonucci, Stefano; Beccara, Silvio a; Aversa, Lucrezia; Nardi, Marco; Verucchi, Roberto; Iannotta, Salvatore; Dapor, Maurizio; and others

    2013-01-28

    In this work, we investigate the processes leading to the room-temperature growth of silicon carbide thin films by supersonic molecular beam epitaxy technique. We present experimental data showing that the collision of fullerene on a silicon surface induces strong chemical-physical perturbations and, for sufficient velocity, disruption of molecular bonds, and cage breaking with formation of nanostructures with different stoichiometric character. We show that in these out-of-equilibrium conditions, it is necessary to go beyond the standard implementations of density functional theory, as ab initio methods based on the Born-Oppenheimer approximation fail to capture the excited-state dynamics. In particular, we analyse the Si-C{sub 60} collision within the non-adiabatic nuclear dynamics framework, where stochastic hops occur between adiabatic surfaces calculated with time-dependent density functional theory. This theoretical description of the C{sub 60} impact on the Si surface is in good agreement with our experimental findings.

  15. Threshold of photoelectron emission from CN{sub x} films deposited at room temperature and at 500 deg. C

    SciTech Connect (OSTI)

    Sago, Genki; Li Wanyan; Goto, Keisuke; Ichikawa, Yo; Ishida, Yoshihisa; Kohiki, Shigemi

    2004-10-15

    The threshold of photoelectron emission was measured for amorphous CN{sub x} films deposited at room temperature (RT) and at 500 deg. C. The x values of the films deposited at RT and at 500 deg. C by magnetron sputtering of a graphite target in a mixed N{sub 2}/Ar gas were 0.6 and 0.3, respectively. Ratios of the sp{sup 2}- to sp{sup 3}-hybridized components of both C and N for the film deposited at 500 deg. C were larger by {approx_equal}4 times than those for the film deposited at RT. The onsets of the electron emission by photon irradiation were 5.0 and 4.7 eV for the films deposited at RT and at 500 deg. C, respectively.

  16. Hydrogen incorporation induced metal-semiconductor transition in ZnO:H thin films sputtered at room temperature

    SciTech Connect (OSTI)

    Singh, Anil; Chaudhary, Sujeet; Pandya, D. K.

    2013-04-29

    The room temperature deposited ZnO:H thin films having high conductivity of 500 Ohm-Sign {sup -1} cm{sup -1} and carrier concentration reaching 1.23 Multiplication-Sign 10{sup 20} cm{sup -3} were reactively sputter deposited on glass substrates in the presence of O{sub 2} and 5% H{sub 2} in Ar. A metal-semiconductor transition at 165 K is induced by the increasing hydrogen incorporation in the films. Hydrogen forms shallow donor complex with activation energy of {approx}10-20 meV at oxygen vacancies (V{sub O}) leading to increase in carrier concentration. Hydrogen also passivates V{sub O} and V{sub Zn} causing {approx}4 times enhancement of mobility to 25.4 cm{sup 2}/V s. These films have potential for use in transparent flexible electronics.

  17. Room-temperature ferromagnetism of Fe-doped TiO{sub 2} nanoparticles driven by oxygen vacancy

    SciTech Connect (OSTI)

    Patel, Sandeep K.S.; Kurian, Sajith; Gajbhiye, Namdeo S.

    2013-02-15

    Graphical abstract: A series of Ti{sub 1−x}Fe{sub x}O{sub 2−δ} (x ≤ 0.03) nanoparticles (NPs) were synthesized by sol–gel route. The room temperature ferromagnetism (RTFM) has been explained in terms of vacancy induced bound magnetic polaron (BMP) model, where the Fe{sup 3+} ions ferromagnetically coupled mediated by oxygen vacancies. Display Omitted Highlights: ► The Fe-doped NPs have been synthesized by sol–gel method. ► Ferromagnetism of Fe-doped TiO{sub 2} NPs are intrinsic property. ► Room temperature ferromagnetism observed in all the Fe-doped samples. ► Variation in M{sub s} is attributed due to oxygen vacancies and defect formation. -- Abstract: A series of Ti{sub 1−x}Fe{sub x}O{sub 2−δ} (0 ≤ x ≤ 0.03) nanoparticles (NPs) were synthesized by sol–gel route. The NPs had a size distribution in the range of 15–40 nm and were identified as the anatase TiO{sub 2} by X-ray diffraction (XRD) and Raman analysis. XRD, selected area electron diffraction, Raman and Mössbauer analysis ruled out the signature of Fe-cluster or any other oxides of Fe. The redshifting of the band edge emission peak observed in UV–vis absorption studies further confirmed the doping of Fe ions in the TiO{sub 2} lattice. Raman studies show the shifting and broadening in E{sub g}(1) and E{sub g}(3) modes with Fe doping. It suggested that the activation of ferromagnetism with increasing Fe doping concentration was related to the oxygen vacancy defects. The presence of such defects was further confirmed from electron paramagnetic resonance (EPR) measurements. The observed ferromagnetism is interpreted in terms of bound magnetic polaron (BMP) model.

  18. Room temperature, hybrid sodium-based flow batteries with multi-electron transfer redox reactions

    SciTech Connect (OSTI)

    Shamie, Jack S.; Liu, Caihong; Shaw, Leon L.; Sprenkle, Vincent L.

    2015-06-11

    We introduce a new concept of hybrid Na-based flow batteries (HNFBs) with a molten Na alloy anode in conjunction with a flowing catholyte separated by a solid Na-ion exchange membrane for grid-scale energy storage. Such HNFBs can operate at ambient temperature, allow catholytes to have multiple electron transfer redox reactions per active ion, offer wide selection of catholyte chemistries with multiple active ions to couple with the highly negative Na alloy anode, and enable the use of both aqueous and non-aqueous catholytes. Further, the molten Na alloy anode permits the decoupled design of power and energy since a large volume of the molten Na alloy can be used with a limited ion-exchange membrane size. In this proof-of-concept study, the feasibility of multielectron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. Furthermore, the critical barriers to mature this new HNFBs have also been explored.

  19. Room Temperature, Hybrid Sodium-Based Flow Batteries with Multi-Electron Transfer Redox Reactions

    SciTech Connect (OSTI)

    Shamie, Jack S.; Liu, Caihong; Shaw, Leon L.; Sprenkle, Vincent L.

    2015-06-11

    We introduce a new concept of hybrid Na-based flow batteries (HNFBs) with a molten Na alloy anode in conjunction with a flowing catholyte separated by a solid Na-ion exchange membrane for grid-scale energy storage. Such HNFBs can operate at ambient temperature, allow catholytes to have multiple electron transfer redox reactions per active ion, offer wide selection of catholyte chemistries with multiple active ions to couple with the highly negative Na alloy anode, and enable the use of both aqueous and non-aqueous catholytes. Further, the molten Na alloy anode permits the decoupled design of power and energy since a large volume of the molten Na alloy can be used with a limited ion-exchange membrane size. In this proof-of-concept study, the feasibility of multielectron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. The critical barriers to mature this new HNFBs have also been explored.

  20. Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy

    SciTech Connect (OSTI)

    Pramanick, S.; Giri, S.; Majumdar, S.; Chatterjee, S.

    2014-09-15

    Present work reports on the observation of large magnetoresistance (??30% at 80 kOe) and magnetocaloric effect (?12?Jkg{sup ?1}K{sup ?1} for 050 kOe) near room temperature (?290?K) on the Ni-excess ferromagnetic shape memory alloy Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56}. The sample can be thought of being derived from the parent Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56} it is found to be optimum (288?K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.

  1. Room temperature, hybrid sodium-based flow batteries with multi-electron transfer redox reactions

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

    Shamie, Jack S.; Liu, Caihong; Shaw, Leon L.; Sprenkle, Vincent L.

    2015-06-11

    We introduce a new concept of hybrid Na-based flow batteries (HNFBs) with a molten Na alloy anode in conjunction with a flowing catholyte separated by a solid Na-ion exchange membrane for grid-scale energy storage. Such HNFBs can operate at ambient temperature, allow catholytes to have multiple electron transfer redox reactions per active ion, offer wide selection of catholyte chemistries with multiple active ions to couple with the highly negative Na alloy anode, and enable the use of both aqueous and non-aqueous catholytes. Further, the molten Na alloy anode permits the decoupled design of power and energy since a large volumemore » of the molten Na alloy can be used with a limited ion-exchange membrane size. In this proof-of-concept study, the feasibility of multielectron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. Furthermore, the critical barriers to mature this new HNFBs have also been explored.« less

  2. Metalized T graphene: A reversible hydrogen storage material at room temperature

    SciTech Connect (OSTI)

    Ye, Xiao-Juan; Zhong, Wei, E-mail: csliu@njupt.edu.cn, E-mail: wzhong@nju.edu.cn; Du, You-Wei [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China); Liu, Chun-Sheng, E-mail: csliu@njupt.edu.cn, E-mail: wzhong@nju.edu.cn [Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing University of Posts and Telecommunications, Nanjing 210023 (China); Zeng, Zhi [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2014-09-21

    Lithium (Li)-decorated graphene is a promising hydrogen storage medium due to its high capacity. However, homogeneous mono-layer coating graphene with lithium atoms is metastable and the lithium atoms would cluster on the surface, resulting in the poor reversibility. Using van der Waals-corrected density functional theory, we demonstrated that lithium atoms can be homogeneously dispersed on T graphene due to a nonuniform charge distribution in T graphene and strong hybridizations between the C-2p and Li-2p orbitals. Thus, Li atoms are not likely to form clusters, indicating a good reversible hydrogen storage. Both the polarization mechanism and the orbital hybridizations contribute to the adsorption of hydrogen molecules (storage capacity of 7.7 wt. %) with an optimal adsorption energy of 0.19 eV/H?. The adsorption/desorption of H? at ambient temperature and pressure is also discussed. Our results can serve as a guide in the design of new hydrogen storage materials based on non-hexagonal graphenes.

  3. Room Temperature, Hybrid Sodium-Based Flow Batteries with Multi-Electron Transfer Redox Reactions

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

    Shamie, Jack S.; Liu, Caihong; Shaw, Leon L.; Sprenkle, Vincent L.

    2015-06-11

    We introduce a new concept of hybrid Na-based flow batteries (HNFBs) with a molten Na alloy anode in conjunction with a flowing catholyte separated by a solid Na-ion exchange membrane for grid-scale energy storage. Such HNFBs can operate at ambient temperature, allow catholytes to have multiple electron transfer redox reactions per active ion, offer wide selection of catholyte chemistries with multiple active ions to couple with the highly negative Na alloy anode, and enable the use of both aqueous and non-aqueous catholytes. Further, the molten Na alloy anode permits the decoupled design of power and energy since a large volumemoreof the molten Na alloy can be used with a limited ion-exchange membrane size. In this proof-of-concept study, the feasibility of multielectron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. The critical barriers to mature this new HNFBs have also been explored.less

  4. Ionic Liquids with Ammonium Cations as Lubricants or Additives

    SciTech Connect (OSTI)

    Qu, Jun; Blau, Peter Julian; Dai, Sheng; Luo, Huimin; Truhan, Jr., John J

    2006-01-01

    Friction and wear are estimated to cost 6% of the US gross national product, or around $700 billion annually. A new class of more effective lubricants could lead to huge energy savings. Limited recent literature has suggested potential for using room-temperature ionic liquids as lubricants, however only a few out of millions (or more) of species have been evaluated. Recent ORNL work discovered a new category of ionic liquids with ammonium cations that have demonstrated promising lubricating properties as net lubricants or lubricant additives, particularly in lubricating difficult-to-lubricate metals like aluminum. More than 30% friction reduction has been observed on ammonium-based ionic liquids compared to conventional hydrocarbon oils. The inherent polarity of ionic liquids is believed to provide strong adhesion to contact surfaces and form a boundary lubricating film leading to friction and wear reductions. Other advantages of ionic liquids include (1) negligible volatility, (2) high thermal stability, (3) non-flammability, and (4) better intrinsic properties that eliminate the necessity of many expensive lubricant additives. With very flexible molecular structures, this new class of lubricants, particularly ammonium-based ionic liquids, can be tailored to fit a big variety of applications including but not limited to bearings, combustion engines, MEMS, and metal forming.

  5. Interaction of Plutonium with Diverse Materials in Moist Air and Nitrogen-Argon Atmospheres at Room Temperature

    SciTech Connect (OSTI)

    John M. Haschke; Raymond J. Martinez; Robert E. Pruner II; Barbara Martinez; Thomas H. Allen

    2001-04-01

    Chemical and radiolytic interactions of weapons-grade plutonium with metallic, inorganic, and hydrogenous materials in atmospheres containing moist air-argon mixtures have been characterized at room temperature from pressure-volume-temperature and mass spectrometric measurements of the gas phase. A reaction sequence controlled by kinetics and gas-phase composition is defined by correlating observed and known reaction rates. In all cases, O{sub 2} is eliminated first by the water-catalyzed Pu + O{sub 2} reaction and H{sub 2}O is then consumed by the Pu + H{sub 2}O reaction, producing a gas mixture of N{sub 2}, argon, and H{sub 2}. Hydrogen formed by the reaction of water and concurrent radiolysis of hydrogenous materials either reacts to form PuH{sub 2} or accumulates in the system. Accumulation of H{sub 2} is correlated with the presence of hydrogenous materials in liquid and volatile forms that are readily distributed over the plutonium surface. Areal rates of radiolytic H{sub 2} generation are determined and applied in showing that modest extents of H{sub 2} production are expected for hydrogenous solids if the contact area with plutonium is limited. The unpredictable nature of complex chemical systems is demonstrated by occurrence of the chloride-catalyzed Pu + H{sub 2}O reaction in some tests and hydride-catalyzed nitriding in another.

  6. Microstructure chemistry and mechanical properties of Ni-based superalloy Rene N4 under irradiation at room temperature

    SciTech Connect (OSTI)

    Sun, C.; Kirk, M.; Li, M.; Hattar, Khalid Mikhiel; Wang, Y.; Anderoglu, O.; Valdez, J.; Uberuaga, B. P.; Dickerson, R.; Maloy, S. A.

    2015-06-14

    Nickel superalloys with cubic L12 structured γ' (Ni3(Al, Ti)) precipitates exhibit high strength at high temperatures and excellent corrosion resistance when exposed to water. Unlike prior studies on irradiation damage of other Ni-based superalloys, our study on Rene N4 involves much larger γ' precipitates, ~450 nm in size, a size regime where the irradiation-induced disordering and dissolution kinetics and the corresponding mechanical property evolution are unknown. Under heavy ion irradiation at room temperature, the submicron-sized γ' precipitates were fully disordered at ~0.3 dpa and only later partially dissolved after 75 dpa irradiation. Nanoindentation experiments indicate that the mechanical properties of the alloy change significantly, with a dramatic decrease in hardness, with irradiation dose. Three contributions to the change in hardness were examined: defect clusters, disordering and dissolution. Moreover, the generation of defect clusters in the matrix and precipitates slightly increased the indentation hardness, while disordering of the submicron-sized γ' precipitates resulted in a dramatic decrease in the total hardness, which decreased further during the early stages of the intermixing between γ' precipitates and matrix (<18 dpa). As a result, controlling the long-range-ordering and chemical intermixing can be used to tailor the mechanical properties of Ni-based superalloys under irradiation.

  7. Microstructure chemistry and mechanical properties of Ni-based superalloy Rene N4 under irradiation at room temperature

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

    Sun, C.; Kirk, M.; Li, M.; Hattar, Khalid Mikhiel; Wang, Y.; Anderoglu, O.; Valdez, J.; Uberuaga, B. P.; Dickerson, R.; Maloy, S. A.

    2015-06-14

    Nickel superalloys with cubic L12 structured γ' (Ni3(Al, Ti)) precipitates exhibit high strength at high temperatures and excellent corrosion resistance when exposed to water. Unlike prior studies on irradiation damage of other Ni-based superalloys, our study on Rene N4 involves much larger γ' precipitates, ~450 nm in size, a size regime where the irradiation-induced disordering and dissolution kinetics and the corresponding mechanical property evolution are unknown. Under heavy ion irradiation at room temperature, the submicron-sized γ' precipitates were fully disordered at ~0.3 dpa and only later partially dissolved after 75 dpa irradiation. Nanoindentation experiments indicate that the mechanical properties ofmore » the alloy change significantly, with a dramatic decrease in hardness, with irradiation dose. Three contributions to the change in hardness were examined: defect clusters, disordering and dissolution. Moreover, the generation of defect clusters in the matrix and precipitates slightly increased the indentation hardness, while disordering of the submicron-sized γ' precipitates resulted in a dramatic decrease in the total hardness, which decreased further during the early stages of the intermixing between γ' precipitates and matrix (<18 dpa). As a result, controlling the long-range-ordering and chemical intermixing can be used to tailor the mechanical properties of Ni-based superalloys under irradiation.« less

  8. A study of room-temperature LixMn1.5Ni0.5O4 solid solutions

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

    Saravanan, Kuppan; Jarry, Angelique; Kostecki, Robert; Chen, Guoying

    2015-01-26

    Understanding the kinetic implication of solid-solution vs. biphasic reaction pathways is critical for the development of advanced intercalation electrode materials. Yet this has been a long-standing challenge in materials science due to the elusive metastable nature of solid solution phases. The present study reports the synthesis, isolation, and characterization of room-temperature LixMn1.5Ni0.5O4 solid solutions. In situ XRD studies performed on pristine and chemically-delithiated, micron-sized single crystals reveal the thermal behavior of LixMn1.5Ni0.5O4 (0 ≤ x ≤ 1) cathode material consisting of three cubic phases: LiMn1.5Ni0.5O4 (Phase I), Li0.5Mn1.5Ni0.5O4 (Phase II) and Mn1.5Ni0.5O4 (Phase III). A phase diagram capturing the structuralmore » changes as functions of both temperature and Li content was established. In conclusion, the work not only demonstrates the possibility of synthesizing alternative electrode materials that are metastable in nature, but also enables in-depth evaluation on the physical, electrochemical and kinetic properties of transient intermediate phases and their role in battery electrode performance.« less

  9. Controllable Growth of Perovskite Films by Room-Temperature Air Exposure for Efficient Planar Heterojunction Photovoltaic Cells

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

    Yang, Bin; Dyck, Ondrej; Poplawsky, Jonathan; Keum, Jong; Das, Sanjib; Puretzky, Alexander; Aytug, Tolga; Joshi, Pooran C.; Rouleau, Christopher M.; Duscher, Gerd; et al

    2015-12-01

    A two-step-solution-processing approach has been established to grow void-free perovskite films for low-cost and high-performance planar heterojunction photovoltaic devices. We generally applied a high-temperature thermal annealing treatment in order to drive the diffusion of CH3NH3I precursor molecules into the compact PbI2 layer to form perovskite films. But, thermal annealing for extended periods would lead to degraded device performance due to the defects generated by decomposition of perovskite into PbI2. In this work, we explored a controllable layer-by-layer spin-coating method to grow bilayer CH3NH3I/PbI2 films, and then drive the interdiffusion between PbI2 and CH3NH3I layers by a simple room-temperature-air-exposure for makingmore » well-oriented, highly-crystalline perovskite films without thermal annealing. This high degree of crystallinity resulted in a carrier diffusion length of ~ 800 nm and high device efficiency of 15.6%, which is comparable to the reported values from thermally-annealed perovskite films based counterparts. Finally, the simplicity and high device performance of this processing approach is highly promising for direct integration into industrial-scale device manufacture.« less

  10. Effects of 1000 C oxide surfaces on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

    SciTech Connect (OSTI)

    Buchanan, R.A.; Perrin, R.L.

    1997-12-01

    Results of electrochemical aqueous-corrosion studies at room temperature indicate that retained in-service-type high-temperature surface oxides (1000 C in air for 24 hours) on FA-129, FAL and FAL-Mo iron aluminides cause major reductions in pitting corrosion resistance in a mild acid-chloride solution designed to simulate aggressive atmospheric corrosion. Removal of the oxides by mechanical grinding restores the corrosion resistance. In a more aggressive sodium tetrathionate solution, designed to simulate an aqueous environment contaminated by sulfur-bearing combustion products, only active corrosion occurs for both the 1000 C oxide and mechanically cleaned surfaces at FAL. Results of slow-strain-rate stress-corrosion-cracking tests on FA-129, FAL and FAL-Mo at free-corrosion and hydrogen-charging potentials in the mild acid chloride solution indicate somewhat higher ductilities (on the order of 50%) for the 1000 C oxides retard the penetration of hydrogen into the metal substrates and, consequently, are beneficial in terms of improving resistance to environmental embrittlement. In the aggressive sodium tetrathionate solution, no differences are observed in the ductilities produced by the 1000 C oxide and mechanically cleaned surfaces for FAL.

  11. Strong room-temperature ferromagnetism of high-quality lightly Mn-doped ZnO grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Zuo Zheng; Zhou Huimei; Olmedo, Mario J.; Kong Jieying; Liu Jianlin; Beyermann, Ward P.; Zheng Jianguo; Xin Yan

    2012-09-01

    Strong room-temperature ferromagnetism is demonstrated in single crystalline Mn-doped ZnO grown by molecular beam epitaxy. With a low Mn concentration of 2 Multiplication-Sign 10{sup 19} cm{sup -3}, Mn-doped ZnO films exhibited room-temperature ferromagnetism with a coercivity field larger than 200 Oe, a large saturation moment of 6 {mu}{sub B}/ion, and a large residue moment that is {approx}70% of the saturation magnetization. Isolated ions with long range carrier mediated spin-spin coupling may be responsible for the intrinsic ferromagnetism.

  12. Phase-Changing Ionic Liquids: CO2 Capture with Ionic Liquids Involving Phase Change

    SciTech Connect (OSTI)

    2010-07-01

    IMPACCT Project: Notre Dame is developing a new CO2 capture process that uses special ionic liquids (ILs) to remove CO2 from the gas exhaust of coal-fired power plants. ILs are salts that are normally liquid at room temperature, but Notre Dame has discovered a new class of ILs that are solid at room temperature and change to liquid when they bind to CO2. Upon heating, the CO2 is released for storage, and the ILs re-solidify and donate some of the heat generated in the process to facilitate further CO2 release. These new ILs can reduce the energy required to capture CO2 from the exhaust stream of a coal-fired power plant when compared to state-ofthe- art technology.

  13. Room temperature ferrimagnetism and ferroelectricity in strained, thin films of BiFe 0.5 Mn 0.5 O 3

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

    Choi, Eun -Mi; Fix, Thomas; Kursumovic, Ahmed; Kinane, Christy J.; Arena, Darío; Sahonta, Suman -Lata; Bi, Zhenxing; Xiong, Jie; Yan, Li; Lee, Jun -Sik; et al

    2014-10-14

    Highly strained films of BiFe0.5Mn0.5O₃ (BFMO) grown at very low rates by pulsed laser deposition were demonstrated to exhibit both ferrimagnetism and ferroelectricity at room temperature and above. Magnetisation measurements demonstrated ferrimagnetism (TC ~ 600K), with a room temperature saturation moment (MS) of up to 90 emu/cc (~ 0.58 μB/f.u) on high quality (001) SrTiO₃. X-ray magnetic circular dichroism showed that the ferrimagnetism arose from antiferromagnetically coupled Fe³⁺ and Mn³⁺. While scanning transmission electron microscope studies showed there was no long range ordering of Fe and Mn, the magnetic properties were found to be strongly dependent on the strain statemore » in the films. The magnetism is explained to arise from one of three possible mechanisms with Bi polarization playing a key role. A signature of room temperature ferroelectricity in the films was measured by piezoresponse force microscopy and was confirmed using angular dark field scanning transmission electron microscopy. The demonstration of strain induced, high temperature multiferroism is a promising development for future spintronic and memory applications at room temperature and above.« less

  14. Room temperature ferrimagnetism and ferroelectricity in strained, thin films of BiFe 0.5 Mn 0.5 O 3

    SciTech Connect (OSTI)

    Choi, Eun -Mi; Fix, Thomas; Kursumovic, Ahmed; Kinane, Christy J.; Arena, Darío; Sahonta, Suman -Lata; Bi, Zhenxing; Xiong, Jie; Yan, Li; Lee, Jun -Sik; Wang, Haiyan; Langridge, Sean; Kim, Young -Min; Borisevich, Albina Y.; MacLaren, Ian; Ramasse, Quentin M.; Blamire, Mark G.; Jia, Quanxi; MacManus-Driscoll, Judith L.

    2014-10-14

    Highly strained films of BiFe0.5Mn0.5O₃ (BFMO) grown at very low rates by pulsed laser deposition were demonstrated to exhibit both ferrimagnetism and ferroelectricity at room temperature and above. Magnetisation measurements demonstrated ferrimagnetism (TC ~ 600K), with a room temperature saturation moment (MS) of up to 90 emu/cc (~ 0.58 μB/f.u) on high quality (001) SrTiO₃. X-ray magnetic circular dichroism showed that the ferrimagnetism arose from antiferromagnetically coupled Fe³⁺ and Mn³⁺. While scanning transmission electron microscope studies showed there was no long range ordering of Fe and Mn, the magnetic properties were found to be strongly dependent on the strain state in the films. The magnetism is explained to arise from one of three possible mechanisms with Bi polarization playing a key role. A signature of room temperature ferroelectricity in the films was measured by piezoresponse force microscopy and was confirmed using angular dark field scanning transmission electron microscopy. The demonstration of strain induced, high temperature multiferroism is a promising development for future spintronic and memory applications at room temperature and above.

  15. Low cost, surfactant-less, one pot synthesis of Cu{sub 2}O nano-octahedra at room temperature

    SciTech Connect (OSTI)

    Ahmed, Asar; Gajbhiye, Namdeo S.; Joshi, Amish G.

    2011-08-15

    Cu{sub 2}O octahedra were successfully synthesized via a novel wet-chemical method using D-glucose and hydrazine as reducing agent at room temperature without the presence of any other surfactant. Presence of D-glucose was important for the stabilization of the evolved copper octahedra and also for facilitating the reduction of the Cu(II) ions. The existence of glucose moieties on the surface as capping agent was confirmed by the FT-IR spectra while there was presence of excess oxygen atoms on the surface leading to the formation of a thin CuO layer at the octahedra surface, as confirmed by the XPS study, probably promoted by the capping glucose. Effect of NaOH concentration on the reaction and the formation of octahedra was also studied. The formation mechanism of obtained Cu{sub 2}O octahedra has been discussed. These octahedra were then studied for their photocatalytic properties in degradation of organic dyes, rhodamine B and methyl orange. - Graphical abstract: Cu{sub 2}O octahedra were found to have thin layer of CuO, due to oxidation of surface Cu{sup +} atoms by the surfactant O atoms. Highlights: > Simple and inexpensive one pot synthesis of various Cu{sub 2}O nanostructures. > Surface properties studied by XPS. > Used as photocatalysis for degradation of rhodamine B.

  16. The analysis of leakage current in MIS Au/SiO{sub 2}/n-GaAs at room temperature

    SciTech Connect (OSTI)

    Altuntas, H.; Ozcelik, S.

    2013-10-15

    The aim of this study is to determine the reverse-bias leakage current conduction mechanisms in Au/SiO{sub 2}/n-GaAs metal-insulator-semiconductor type Schottky contacts. Reverse-bias current-voltage measurements (I-V) were performed at room temperature. The using of leakage current values in SiO{sub 2} at electric fields of 1.46-3.53 MV/cm, ln(J/E) vs. {radical}E graph showed good linearity. Rom this plot, dielectric constant of SiO{sub 2} was calculated as 3.7 and this value is perfect agreement with 3.9 which is value of SiO{sub 2} dielectric constant. This indicates, Poole-Frenkel type emission mechanism is dominant in this field region. On the other hand, electric fields between 0.06-0.73 and 0.79-1.45 MV/cm, dominant leakage current mechanisms were found as ohmic type conduction and space charge limited conduction, respectively.

  17. Constructing hierarchical interfaces: TiO2-supported PtFe-FeOx nanowires for room temperature CO oxidation

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

    Zhu, Huiyuan; Wu, Zili; Dong, Su; Veith, Gabriel M.; Lu, Hanfeng; Zhang, Pengfei; Chai, Song -Hai; Dai, Sheng

    2015-08-05

    This is a report of a facile approach to constructing catalytic active hierarchical interfaces in one-dimensional (1D) nanostructure, exemplified by the synthesis of TiO2-supported PtFe–FeOx nanowires (NWs). The hierarchical interface, constituting atomic level interactions between PtFe and FeOx within each NW and the interactions between NWs and support (TiO2), enables CO oxidation with 100% conversion at room temperature. We identify the role of the two interfaces by probing the CO oxidation reaction with isotopic labeling experiments. Both the oxygen atoms (Os) in FeOx and TiO2 participate in the initial CO oxidation, facilitating the reaction through a redox pathway. Moreover, themore » intact 1D structure leads to the high stability of the catalyst. After 30 h in the reaction stream, the PtFe–FeOx/TiO2 catalyst exhibits no activity decay. These results provide a general approach and new insights into the construction of hierarchical interfaces for advanced catalysis.« less

  18. Room temperature deformation mechanisms of alumina particles observed from in situ micro-compression and atomistic simulations.

    SciTech Connect (OSTI)

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay D.; Mook, William M.; Bufford, Daniel Charles; Boyce, Brad L.; Hattar, Khalid Mikhiel; Kotula, Paul G.; Hall, Aaron Christopher

    2015-09-22

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containing numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. As a result, the identified deformation mechanisms provide insight into feedstock design for AD.

  19. Oxygen-vacancy-induced room-temperature magnetization in lamellar V{sub 2}O{sub 5} thin films

    SciTech Connect (OSTI)

    Cezar, A. B.; Graff, I. L. Varalda, J.; Schreiner, W. H.; Mosca, D. H.

    2014-10-28

    In this work, we study the local atomic and electronic structures as well as oxygen-vacancy-induced magnetic properties of electrodeposited V{sub 2}O{sub 5} films. Unlike stoichiometric V{sub 2}O{sub 5}, which is a diamagnetic lamellar semiconductor, our oxygen-defective V{sub 2}O{sub 5} films are ferromagnetic at room-temperature and their saturation magnetization decreases with air exposure time. X-ray absorption spectroscopy was used to monitor the aging effect on these films, revealing that freshly-made samples exhibit only local crystalline order, whereas the aged ones undoubtedly show an enhancement of crystallinity and coordination symmetry. The mean number of oxygen atoms around V tends to increase, indicating a decrease of oxygen vacancies with time. Concurrently with the decrease of oxygen vacancies, a loss of saturation magnetization is also observed. Hence, it can be concluded that the ferromagnetism of the V{sub 2}O{sub 5} films originates from a vacancy-induced mechanism, confirming the universality of this class of ferromagnetism.

  20. Room temperature deformation mechanisms of alumina particles observed from in situ micro-compression and atomistic simulations.

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

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay D.; Mook, William M.; Bufford, Daniel Charles; Boyce, Brad L.; Hattar, Khalid Mikhiel; Kotula, Paul G.; Hall, Aaron Christopher

    2015-09-22

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containingmore » numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. As a result, the identified deformation mechanisms provide insight into feedstock design for AD.« less

  1. Extremely high-rate, uniform dissolution of alloy C-22 in anhydrous organic solutions at room temperature

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

    Schindelholz, Eric J.; Christie, Michael A.; Allwein, Shawn P.; Kelly, Robert G.

    2016-06-21

    During routine pharmaceutical development and scale-up work, severe corrosion of a Hastelloy Alloy C-22 filter dryer was observed after single, short (several hours) contact with the product slurry at room temperature. Initial investigations showed that the presence of both 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and HCl was sufficient in an acetonitrile solution to cause rapid corrosion of C-22. More detailed mass loss studies showed initial corrosion rates exceeding25 mm/year that then decreased over several hours to steady state rates of 3-5 mm/year. The corrosion was highly uniform. Electrochemical measurements demonstrated that although C-22 is spontaneously passive in acetonitrile solution, the presence of HClmore » leads to the development of a transpassive region. Furthermore, DDQ is a sufficiently strong oxidizer, particularly in acidic solutions, to polarize the C-22 well into the transpassive region, leading to the observed high corrosion rates.« less

  2. Manipulation of Zeeman coherence in solids at room temperature: Ramsey interference in the coherent-population-trapping spectrum of ruby

    SciTech Connect (OSTI)

    Kolesov, Roman; Scully, Marlan O.; Kocharovskaya, Olga

    2006-11-15

    Coherent population trapping (CPT) in a three-level atomic medium pumped by two subsequent short optical pulses is considered under the condition of negligible population decay from the excited optical state. It is shown that the amount of atomic population transferred to the excited state by the combined action of the pulses strongly depends on the phase of the ground-state coherence excited by the first pulse at the arrival time of the second pulse. Oscillatory behavior of optical excitation efficiency on the time delay between the pulses is predicted. It is also shown that saturating optical pulses can produce population inversion in a resonantly pumped quasi-two-level system. A class of solid materials in which the predicted phenomena can be observed at room temperature is found. It includes some rare-earth and transition-metal doped dielectric crystals where Orbach relaxation between ground-state Zeeman states is suppressed: ruby, alexandrite, and several others. On the basis of the theoretical predictions, experimental observation of Ramsey fringes in CPT spectrum of ruby is reported.

  3. Post-annealing effect on the room-temperature ferromagnetism in Cu-doped ZnO thin films

    SciTech Connect (OSTI)

    Hu, Yu-Min Kuang, Chein-Hsiun; Han, Tai-Chun; Yu, Chin-Chung; Li, Sih-Sian

    2015-05-07

    In this work, we investigated the structural and magnetic properties of both as-deposited and post-annealed Cu-doped ZnO thin films for better understanding the possible mechanisms of room-temperature ferromagnetism (RT-FM) in ZnO-based diluted magnetic oxides. All of the films have a c-axis-oriented wurtzite structure and display RT-FM. X-ray photoelectron spectroscopy results showed that the incorporated Cu ions in as-deposited films are in 1+ valence state merely, while an additional 2+ valence state occurs in post-annealed films. The presence of Cu{sup 2+} state in post-annealed film accompanies a higher magnetization value than that of as-deposited film and, in particular, the magnetization curves at 10 K and 300 K of the post-annealed film separate distinctly. Since Cu{sup 1+} ion has a filled 3d band, the RT-FM in as-deposited Cu-doped ZnO thin films may stem solely from intrinsic defects, while that in post-annealed films is enhanced due to the presence of CuO crystallites.

  4. Giant room-temperature barocaloric effect and pressure-mediated electrocaloric effect in BaTiO{sub 3} single crystal

    SciTech Connect (OSTI)

    Liu, Yang; Wei, Jie; Janolin, Pierre-Eymeric; Infante, Ingrid C.; Dkhil, Brahim E-mail: xlou03@mail.xjtu.edu.cn; Lou, Xiaojie E-mail: xlou03@mail.xjtu.edu.cn

    2014-04-21

    Barocaloric effect in BaTiO{sub 3} single crystal is studied by a thermodynamic phenomenological model. It is demonstrated that a giant barocaloric effect can be achieved near room temperature with an adiabatic temperature change of more than 3 K and a temperature span about 50 K. As expected, the electrocaloric peak can be shifted towards room temperature by pressure. However, a slight reduction of the electrocaloric peak is found in contrast to relaxor ferroelectrics and LiNbO{sub 3}. We believe that our findings could open a potential route by combining the barocaloric effect and pressure-mediated electrocaloric effect in BaTiO{sub 3} single crystal for cooling devices.

  5. Room temperature atomic layerlike deposition of ZnS on organic thin films: Role of substrate functional groups and precursors

    SciTech Connect (OSTI)

    Shi, Zhiwei; Walker, Amy V.

    2015-09-15

    The room temperature atomic layerlike deposition (ALLD) of ZnS on functionalized self-assembled monolayers (SAMs) was investigated, using diethyl zinc (DEZ) and in situ generated H{sub 2}S as reactants. Depositions on SAMs with three different terminal groups, –CH{sub 3,} –OH, and –COOH, were studied. It was found that the reaction of DEZ with the SAM terminal group is critical in determining the film growth rate. Little or no deposition is observed on –CH{sub 3} terminated SAMs because DEZ does not react with the methyl terminal group. ZnS does deposit on both –OH and –COOH terminated SAMs, but the grow rate on –COOH terminated SAMs is ∼10% lower per cycle than on –OH terminated SAMs. DEZ reacts with the hydroxyl group on –OH terminated SAMs, while on –COOH terminated SAMs it reacts with both the hydroxyl and carbonyl bonds of the terminal groups. The carbonyl reaction is found to lead to the formation of ketones rather than deposition of ZnS, lowering the growth rate on –COOH terminated SAMs. SIMS spectra show that both –OH and –COOH terminated SAMs are covered by the deposited ZnS layer after five ALLD cycles. In contrast to ZnO ALLD where the composition of the film differs for the first few layers on –COOH and –OH terminated SAMs, the deposited film composition is the same for both –COOH and –OH terminated SAMs. The deposited film is found to be Zn-rich, suggesting that the reaction of H{sub 2}S with the Zn-surface adduct may be incomplete.

  6. Enlarged Mn 3s splitting and room-temperature ferromagnetism in epitaxially grown oxygen doped Mn{sub 2}N{sub 0.86} films

    SciTech Connect (OSTI)

    Meng, M.; Wu, S. X. Ren, L. Z.; Zhou, W. Q.; Wang, Y. J.; Wang, G. L.; Li, S. W.

    2014-11-07

    Single-phase and oxygen doped Mn{sub 2}N{sub 0.86} thin films have been grown on MgO (111) by plasma-assisted molecular beam epitaxy. The films grow under tensile strain and, remarkably, they show ferromagnetic-like interactions at low temperature and ferromagnetic ordering agreed well with the Bloch-law T{sup 3/2} at room-temperature. We further demonstrate the enlarged Mn 3s splitting (6.46 eV) and its possible relation to the observed ferromagnetism. Our study not only provide a strategy for further theoretical work on oxygen doped manganese nitrides, but also shed promising light on utilizing its room-temperature FM property to fabricate spintronic devices.

  7. Optical diode effect at spin-wave excitations in the room-temperature multiferroic BiFeO3.

    SciTech Connect (OSTI)

    Kezsmarki, I.; Nagel, U.; Bordacs, S.; Fishman, Randy Scott; Lee, Jun Hee; Yi, Hee Taek; Cheong, Sang-Wook; Room, T.

    2015-09-15

    The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO3 over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. Our findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.

  8. Crosslinked polymer gel electrolytes based on polyethylene glycol methacrylate and ionic liquid for lithium battery applications

    SciTech Connect (OSTI)

    Liao, Chen; Sun, Xiao-Guang; Dai, Sheng

    2013-01-01

    Gel polymer electrolytes were synthesized by copolymerization polyethylene glycol methyl ether methacrylate with polyethylene glycol dimethacrylate in the presence of a room temperature ionic liquid, methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPY TFSI). The physical properties of gel polymer electrolytes were characterized by thermal analysis, impedance spectroscopy, and electrochemical tests. The ionic conductivities of the gel polymer electrolytes increased linearly with the amount of MPPY TFSI and were mainly attributed to the increased ion mobility as evidenced by the decreased glass transition temperatures. Li||LiFePO4 cells were assembled using the gel polymer electrolytes containing 80 wt% MPPY TFSI via an in situ polymerization method. A reversible cell capacity of 90 mAh g 1 was maintained under the current density of C/10 at room temperature, which was increased to 130 mAh g 1 by using a thinner membrane and cycling at 50 C.

  9. Electro-caloric effect in lead-free Sn doped BaTiO{sub 3} ceramics at room temperature and low applied fields

    SciTech Connect (OSTI)

    Upadhyay, Sanjay Kumar; Reddy, V. Raghavendra E-mail: vrreddy@csr.res.in; Bag, Pallab; Rawat, R.; Gupta, S. M.; Gupta, Ajay

    2014-09-15

    Structural, dielectric, ferroelectric (FE), {sup 119}Sn Mössbauer, and specific heat measurements of polycrystalline BaTi{sub 1–x}Sn{sub x}O{sub 3} (x = 0% to 15%) ceramics are reported. Phase purity and homogeneous phase formation with Sn doping is confirmed from x-ray diffraction and {sup 119}Sn Mössbauer measurements. With Sn doping, the microstructure is found to change significantly. Better ferroelectric properties at room temperature, i.e., increased remnant polarization (38% more) and very low field switchability (225% less) are observed for x = 5% sample as compared to other samples and the results are explained in terms of grain size effects. With Sn doping, merging of all the phase transitions into a single one is observed for x ≥ 10% and for x = 5%, the tetragonal to orthorhombic transition temperature is found close to room temperature. As a consequence better electro-caloric effects are observed for x = 5% sample and therefore is expected to satisfy the requirements for non-toxic, low energy (field) and room temperature based applications.

  10. Room temperature photoluminescence from In{sub x}Al{sub (1?x)}N films deposited by plasma-assisted molecular beam epitaxy

    SciTech Connect (OSTI)

    Kong, W. Jiao, W. Y.; Kim, T. H.; Brown, A. S.; Mohanta, A.; Roberts, A. T.; Fournelle, J.; Losurdo, M.; Everitt, H. O.

    2014-09-29

    InAlN films deposited by plasma-assisted molecular beam epitaxy exhibited a lateral composition modulation characterized by 1012?nm diameter, honeycomb-shaped, columnar domains with Al-rich cores and In-rich boundaries. To ascertain the effect of this microstructure on its optical properties, room temperature absorption and photoluminescence characteristics of In{sub x}Al{sub (1?x)}N were comparatively investigated for indium compositions ranging from x?=?0.092 to 0.235, including x?=?0.166 lattice matched to GaN. The Stokes shift of the emission was significantly greater than reported for films grown by metalorganic chemical vapor deposition, possibly due to the phase separation in these nanocolumnar domains. The room temperature photoluminescence also provided evidence of carrier transfer from the InAlN film to the GaN template.

  11. Reading Room

    Broader source: Energy.gov [DOE]

    Welcome to the Freedom of Information Act (FOIA) Electronic Reading Room for the Department of Energy at Headquarters.

  12. Grain size and texture effect on compression behavior of hot-extruded Mg-3Al-1Zn alloys at room temperature

    SciTech Connect (OSTI)

    Chang, L.L. [Department of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Y.N., E-mail: wynmm@dlut.edu.cn [Department of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zhao, X. [Key laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110005 (China); Qi, M. [Department of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2009-09-15

    Hot-extruded AZ31 alloy was subjected to compression at room temperature. The influence of grain size and grain orientation on the compression behavior of the specimens was examined by optical microscopy, compression test and X-ray diffraction. Abundant twins activated during compression of extruded AZ31 magnesium alloy. The hot extruded AZ31 magnesium alloys had a higher Hall-Petch slope for compression than that for tension.

  13. An Investigation of Enhanced Formability in AA5182-O Al During High-Rate Fre-Forming at Room-Temperature: Quantification of Deformation History

    SciTech Connect (OSTI)

    Rohatgi, Aashish; Soulami, Ayoub; Stephens, Elizabeth V.; Davies, Richard W.; Smith, Mark T.

    2014-03-01

    Following the two prior publication of PNNL Pulse-Pressure research in the Journal of Materials Processing Technology, this manuscript continues to describe PNNLs advances in getting a better understanding of sheet metal formability under high strain-rate conditions. Specifically, using a combination of numerical modeling and novel experiments, we quantitatively demonstrate the deformation history associated with enhanced formability (~2.5X) in Al under room temperature forming.

  14. Li-rich anti-perovskite Li3OCl films with enhanced ionic conductivity

    SciTech Connect (OSTI)

    Lu, XJ; Wu, G; Howard, JW; Chen, AP; Zhao, YS; Daemen, LL; Jia, QX

    2014-08-13

    Anti-perovskite solid electrolyte films were prepared by pulsed laser deposition, and their room-temperature ionic conductivity can be improved by more than an order of magnitude in comparison with its bulk counterpart. The cyclability of Li3OCl films in contact with lithium was evaluated using a Li/Li3OCl/Li symmetric cell, showing self-stabilization during cycling test.

  15. Single phase synthesis and room temperature neutron diffraction studies on multiferroic PbFe{sub 0.5}Nb{sub 0.5}O{sub 3}

    SciTech Connect (OSTI)

    Matteppanavar, Shidaling; Angadi, Basavaraj; Rayaprol, Sudhindra

    2013-02-05

    The lead-iron-niobate, (PbFe{sub 0.5}Nb{sub 0.5}O{sub 3} or PFN) was synthesized by low temperature sintering Single Step / Solid State Reaction Method. The 700 Degree-Sign C/2 hrs. calcined powder was sintered at 1050 Degree-Sign C/1 hr. The sintered pellets were characterized through X-Ray Diffraction and Neutron Diffraction at room temperature. It is found from the XRD pattern that the materials is in single phase with no traces of pyrochlore phase. It was also confirmed from the neutron diffraction pattern, the structure of PFN to be monoclinic, space group Cm. Structural studies has been carried out by refining the obtained neutron diffraction data by Rietveld refinement method using Fullprof program. The neutron diffraction pattern at 300 K (room temperature) was selected to refine the structure. The lattice parameters obtained are; a = 5.6709 A, b = 5.6732 A, c = 4.0136 A, and {alpha}= 90, {beta}= 89.881, {gamma}= 90. The P-E measurements showed hysteretic behavior with high remnant polarization.

  16. Room temperature ferromagnetic and ferroelectric properties of Bi{sub 1−x}Ca{sub x}MnO{sub 3} thin films

    SciTech Connect (OSTI)

    Pugazhvadivu, K. S.; Tamilarasan, K.; Balakrishnan, L.; Mohan Rao, G.

    2014-11-15

    Bi{sub 1−x}Ca{sub x}MnO{sub 3} (BCMO) thin films with x = 0, 0.1, 0.2, 0.3 and 0.4 are successfully deposited on the n-type Si (100) substrate at two different temperatures of 400 °C and 800 °C using RF magnetron sputtering. The stoichiometry of the films and oxidation state of the elements have been described by X-ray photoelectron spectroscopy analysis. Dielectric measurement depicts the insulating property of BCMO films. Magnetic and ferroelectric studies confirm the significant enhancement in spin orientation as well as electric polarization at room temperature due to incorporation of Ca{sup 2+} ions into BiMnO{sub 3} films. The BCMO (x = 0.2) film grown at 400 °C shows better magnetization (M{sub sat}) and polarization (P{sub s})with the measured values of 869 emu / cc and 6.6 μ{sub C}/ cm{sup 2} respectively than the values of the other prepared films. Thus the realization of room temperature ferromagnetic and ferroelectric ordering in Ca{sup 2+} ions substituted BMO films makes potentially interesting for spintronic device applications.

  17. Orthorhombic-tetragonal phase coexistence and enhanced piezo-response at room temperature in Zr, Sn, and Hf modified BaTiO{sub 3}

    SciTech Connect (OSTI)

    Kalyani, Ajay Kumar; Brajesh, Kumar; Ranjan, Rajeev; Senyshyn, Anatoliy

    2014-06-23

    The effect of Zr, Hf, and Sn in BaTiO{sub 3} has been investigated at close composition intervals in the dilute concentration limit. Detailed structural analysis by x-ray and neutron powder diffraction revealed that merely 2 mol. % of Zr, Sn, and Hf stabilizes a coexistence of orthorhombic (Amm2) and tetragonal (P4mm) phases at room temperature. As a consequence, all the three systems show substantial enhancement in the longitudinal piezoelectric coefficient (d{sub 33}), with Sn modification exhibiting the highest value ∼425 pC/N.

  18. Room-temperature ferromagnetism in Cr-doped Si achieved by controlling atomic structure, Cr concentration, and carrier densities: A first-principles study

    SciTech Connect (OSTI)

    Wei, Xin-Yuan; Yang, Zhong-Qin; Zhu, Yan; Li, Yun

    2015-04-28

    By using first-principles calculations, we investigated how to achieve a strong ferromagnetism in Cr-doped Si by controlling the atomic structure and Cr concentration as well as carrier densities. We found that the configuration in which the Cr atom occupies the tetrahedral interstitial site can exist stably and the Cr atom has a large magnetic moment. Using this doping configuration, room-temperature ferromagnetism can be achieved in both n-type and p-type Si by tuning Cr concentration and carrier densities. The results indicate that the carrier density plays a crucial role in realizing strong ferromagnetism in diluted magnetic semiconductors.

  19. Density dependence of the room temperature thermal conductivity of atomic layer deposition-grown amorphous alumina (Al{sub 2}O{sub 3})

    SciTech Connect (OSTI)

    Gorham, Caroline S.; Gaskins, John T.; Hopkins, Patrick E.; Parsons, Gregory N.; Losego, Mark D.

    2014-06-23

    We report on the thermal conductivity of atomic layer deposition-grown amorphous alumina thin films as a function of atomic density. Using time domain thermoreflectance, we measure the thermal conductivity of the thin alumina films at room temperature. The thermal conductivities vary ?35% for a nearly 15% change in atomic density and are substrate independent. No density dependence of the longitudinal sound speeds is observed with picosecond acoustics. The density dependence of the thermal conductivity agrees well with a minimum limit to thermal conductivity model that is modified with a differential effective-medium approximation.

  20. Multiple current peaks in room-temperature atmospheric pressure homogenous dielectric barrier discharge plasma excited by high-voltage tunable nanosecond pulse in air

    SciTech Connect (OSTI)

    Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Tang, Kai; Liu, Zhi-jie; Wang, Sen

    2013-05-13

    Room temperature homogenous dielectric barrier discharge plasma with high instantaneous energy efficiency is acquired by using nanosecond pulse voltage with 20-200 ns tunable pulse width. Increasing the voltage pulse width can lead to the generation of regular and stable multiple current peaks in each discharge sequence. When the voltage pulse width is 200 ns, more than 5 organized current peaks can be observed under 26 kV peak voltage. Investigation also shows that the organized multiple current peaks only appear in homogenous discharge mode. When the discharge is filament mode, organized multiple current peaks are replaced by chaotic filament current peaks.

  1. Probing the interaction of ionic liquids with graphene using surface-enhanced Raman spectroscopy

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

    Mahurin, Shannon Mark; Dai, Sheng; Surwade, Sumedh P.; Crespo, Marcos

    2015-12-17

    We report an in situ measurement of the interaction of an imidazolium-based room temperature ionic liquid with both pure silver and a graphene-over-silver electrode under an applied electrochemical potential. At a negative applied potential, overall signal intensity increased indicating enhanced ionic liquid concentration at both silver and graphene electrodes. Vibrational modes associated with the imidazolium ring exhibited greater intensity enhancements and larger peak shifts compared with the anion indicating that the cation adsorbs with the ring and alkyl chain parallel to the electrode surface for both silver and graphene. In contrast to the silver, the surface enhanced Raman spectra ofmore » the ionic liquid near graphene showed shifts in the cation peaks even at no applied potential because of the strong π–π interaction between the ionic liquid and the graphene. Furthermore, the intensity of the graphene peak decreased in the presence of ionic liquid possibly due to the interaction between the ionic liquid and graphene. In conclusion, these results illustrate the effectiveness of surface-enhanced Raman spectroscopy to investigate electrolyte interactions with graphene at the liquid/electrode interface.« less

  2. Probing the interaction of ionic liquids with graphene using surface-enhanced Raman spectroscopy

    SciTech Connect (OSTI)

    Mahurin, Shannon Mark; Dai, Sheng; Surwade, Sumedh P.; Crespo, Marcos

    2015-12-17

    We report an in situ measurement of the interaction of an imidazolium-based room temperature ionic liquid with both pure silver and a graphene-over-silver electrode under an applied electrochemical potential. At a negative applied potential, overall signal intensity increased indicating enhanced ionic liquid concentration at both silver and graphene electrodes. Vibrational modes associated with the imidazolium ring exhibited greater intensity enhancements and larger peak shifts compared with the anion indicating that the cation adsorbs with the ring and alkyl chain parallel to the electrode surface for both silver and graphene. In contrast to the silver, the surface enhanced Raman spectra of the ionic liquid near graphene showed shifts in the cation peaks even at no applied potential because of the strong π–π interaction between the ionic liquid and the graphene. Furthermore, the intensity of the graphene peak decreased in the presence of ionic liquid possibly due to the interaction between the ionic liquid and graphene. In conclusion, these results illustrate the effectiveness of surface-enhanced Raman spectroscopy to investigate electrolyte interactions with graphene at the liquid/electrode interface.

  3. Spin-Induced Polarizations and Nonreciprocal Directional Dichroism of the Room-Temperature Multiferroic BiFeO3

    SciTech Connect (OSTI)

    Fishman, Randy Scott; Lee, Jun Hee; Bordacs, Sandor; Kezsmarki, Istvan; Nagel, Urmas; Room, Toomas

    2015-09-14

    A microscopic model for the room-temperature multiferroic BiFeO3 that includes two Dzyaloshinskii-Moriya interactions and single-ion anisotropy along the ferroelectric polarization predicts both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field. Due to simultaneously broken time-reversal and spatial-inversion symmetries, the absorption of light changes as the magnetic field or the direction of light propagation is reversed. We discuss three physical mechanisms that may contribute to this absorption asymmetry known as directional dichroism: the spin current, magnetostriction, and single-ion anisotropy. We conclude that the directional dichroism in BiFeO3 is dominated by the spin-current polarization and is insensitive to the magnetostriction and easy-axis anisotropy. With three independent spin-current parameters, our model accurately describes the directional dichroism observed for magnetic field along [1, -1, 0]. Since some modes are almost transparent to light traveling in one direction but opaque for light traveling in the opposite direction, BiFeO3 can be used as a room-temperature optical diode at certain frequencies in the GHz to THz range. This work demonstrates that an analysis of the directional dichroism spectra based on an effective spin model supplemented by first-principles calculations can produce a quantitative microscopic theory of the magnetoelectric couplings in multiferroic materials.

  4. Room-temperature thermally induced relaxation effect in a two-dimensional cyano-bridged Cu-Mo bimetal assembly and thermodynamic analysis of the relaxation process

    SciTech Connect (OSTI)

    Umeta, Yoshikazu; Ozaki, Noriaki; Tokoro, Hiroko; Ohkoshi, Shin-ichi

    2013-04-15

    We observed a photo-switching effect in [Cu{sup II}(1,4,8,11-tetraazacyclodecane)]{sub 2}[Mo{sup IV}(CN){sub 8}]{center_dot}10H{sub 2}O by irradiation with 410-nm light around room temperature using infrared spectroscopy. This photo-switching is caused by the photo-induced charge transfer from Mo{sup IV} to Cu{sup II}. The photo-induced phase thermally relaxed to the initial phase with a half-life time of 2.7 Multiplication-Sign 10{sup 1}, 6.9 Multiplication-Sign 10{sup 1}, and 1.7 Multiplication-Sign 10{sup 2} s at 293, 283, and 273 K, respectively. The relaxation process was analyzed using Hauser's equation, k=k{sub 0}exp[-(E{sub a}+E{sub a}{sup *}{gamma}) /k{sub B}T], where k is the rate constant of relaxation, k{sub 0} is the frequency factor, E{sub a} is the activation energy, E{sub a}{sup *} is the additional activation energy due to the cooperativity, and {gamma} is the fraction of the photo-induced phase. k{sub 0}, E{sub a}, and E{sub a}{sup *} were evaluated as 1.28 Multiplication-Sign 10{sup 7}{+-} 2.6 s{sup -1}, 4002 {+-} 188 cm{sup -1}, and 546 {+-} 318 cm{sup -1}, respectively. The value of E{sub a} is much larger than that of the relaxation process for the typical light-induced spin crossover effect (E{sub a} Almost-Equal-To 1000 cm{sup -1}). Room-temperature photo-switching is an important issue in the field of optical functional materials. The present system is useful for the demonstration of high-temperature photo-switching material.

  5. Room temperature reaction of oxygen with gold: an in situ ambient-pressure X-ray photoelectron spectroscopy investigation

    SciTech Connect (OSTI)

    Jiang, Peng; Porsgaard, Soeren; Borondics, Ferenc; Kober, Mariana; Caballero, Alfonso; Bluhm, Hendrik; Besenbacher, Flemming; Salmeron, Miquel

    2010-02-01

    Gold is commonly regarded as the most inert element.1 However, the discovery of the exceptional catalytic properties of gold nanoparticles (NPs) for low temperature CO oxidation2 initiated great interest due to its promising applications and spawned a large number of studies devoted to the understanding of the reaction mechanism.3-6 Nevertheless, no consistent and conclusive picture has arisen.7-13

  6. Modified normal-phase ion-pair chromatographic methods for the facile separation and purification of imidazolium-based ionic compounds

    SciTech Connect (OSTI)

    Urban, ND; Schenkel, MR; Robertson, LA; Noble, RD; Gin, DL

    2012-07-04

    lmidazolium- and oligo(imidazolium)-based ionic organic compounds are important in the design of room-temperature ionic liquid materials; however, the chromatographic analysis and separation of such compounds are often difficult. A convenient and inexpensive method for effective thin-layer chromatography (TLC) analysis and column chromatography separation of imidazolium-based ionic compounds is presented. Normal-phase ion-pair TLC is used to effectively analyze homologous mixtures of these ionic compounds. Subsequent separation of the mixtures is performed using ion-pair flash chromatography on normal-phase silica gel, yielding high levels of recovery. This method also results in a complete exchange of the counter anion on the imidazolium compounds to the anion of the ion-pair reagent. (C) 2012 Elsevier Ltd. All rights reserved.

  7. Facile fabrication of high-performance InGaZnO thin film transistor using hydrogen ion irradiation at room temperature

    SciTech Connect (OSTI)

    Ahn, Byung Du [School of Electrical and Electronic Engineering, 50, Yonsei University, Seoul 120-749 (Korea, Republic of); Park, Jin-Seong [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Chung, K. B., E-mail: kbchung@dongguk.edu [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of)

    2014-10-20

    Device performance of InGaZnO (IGZO) thin film transistors (TFTs) are investigated as a function of hydrogen ion irradiation dose at room temperature. Field effect mobility is enhanced, and subthreshold gate swing is improved with the increase of hydrogen ion irradiation dose, and there is no thermal annealing. The electrical device performance is correlated with the electronic structure of IGZO films, such as chemical bonding states, features of the conduction band, and band edge states below the conduction band. The decrease of oxygen deficient bonding and the changes in electronic structure of the conduction band leads to the improvement of device performance in IGZO TFT with an increase of the hydrogen ion irradiation dose.

  8. Thermodynamic understanding of Sn whisker growth on the Cu surface in Cu(top)-Sn(bottom) bilayer system upon room temperature aging

    SciTech Connect (OSTI)

    Huang, Lin; Jian, Wei; Lin, Bing; Wang, Jiangyong; Wen, Yuren; Gu, Lin

    2015-06-07

    Sn whiskers are observed by scanning electron microscope on the Cu surface in Cu(top)-Sn(bottom) bilayer system upon room temperature aging. Only Cu{sub 6}Sn{sub 5} phase appears in the X-ray diffraction patterns and no Sn element is detected in the Cu sublayer by scanning transmission electron microscopy. Based on the interfacial thermodynamics, the intermetallic Cu{sub 6}Sn{sub 5} compound phase may form directly at the Sn grain boundary. Driven by the stress gradient during the formation of Cu{sub 6}Sn{sub 5} compound at Sn grain boundaries, Sn atoms segregate onto the Cu surface and accumulate to form Sn whisker.

  9. Polymeric electrolytes for ambient temperature lithium batteries

    SciTech Connect (OSTI)

    Farrington, G.C. . Dept. of Materials Science and Engineering)

    1991-07-01

    A new type of highly conductive Li{sup +} polymer electrolyte, referred to as the Innovision polymer electrolyte, is completely amorphous at room temperature and has an ionic conductivity in the range of 10{sup {minus}3} S/cm. This report discusses the electrochemical characteristics (lithium oxidation and reduction), conductivity, and physical properties of Innovision electrolytes containing various dissolved salts. These electrolytes are particularly interesting since they appear to have some of the highest room-temperature lithium ion conductivities yet observed among polymer electrolytes. 13 refs. 11 figs., 2 tabs.

  10. Implications of room temperature oxidation on crystal structure and exchange bias effect in Co/CoO nanoparticles

    SciTech Connect (OSTI)

    Feygenson, Mikhail; Formo, Eric V.; Freeman, Katherine; Schieber, Natalie P.; Gai, Zheng; Rondinone, Adam J.

    2015-11-02

    In this study, we describe how the exchange bias effect in Co/CoO nanoparticles depends on the size focusing and temperature treatment of precursor Co nanoparticles before oxidation at ambient conditions. By appealing to magnetization, microscopy, neutron and synchrotron x-ray measurements we found that as-synthesized Co nanoparticles readily oxidize in air only after 20 days. The highest exchange bias field of 814 Oe is observed at T = 2K. When the same nanoparticles are centrifuged and annealed at 70 °C in vacuum prior to oxidation, the exchange bias field is increased to 2570 Oe. Annealing of Co nanoparticles in vacuum improves their crystallinity and prevents complete oxidation, so that Co-core/CoO-shell structure is preserved even after 120 days. The crystal structure of CoO shell in both samples is different from its bulk counterpart. Implications of such distorted CoO shells on exchange bias are discussed. Coating of Co nanoparticles with amorphous silica shell makes them resistant to oxidation, but ultimately modifies the crystal structure of both Co core and SiO2 shell.

  11. Implications of room temperature oxidation on crystal structure and exchange bias effect in Co/CoO nanoparticles

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

    Feygenson, Mikhail; Formo, Eric V.; Freeman, Katherine; Schieber, Natalie P.; Gai, Zheng; Rondinone, Adam J.

    2015-11-02

    In this study, we describe how the exchange bias effect in Co/CoO nanoparticles depends on the size focusing and temperature treatment of precursor Co nanoparticles before oxidation at ambient conditions. By appealing to magnetization, microscopy, neutron and synchrotron x-ray measurements we found that as-synthesized Co nanoparticles readily oxidize in air only after 20 days. The highest exchange bias field of 814 Oe is observed at T = 2K. When the same nanoparticles are centrifuged and annealed at 70 °C in vacuum prior to oxidation, the exchange bias field is increased to 2570 Oe. Annealing of Co nanoparticles in vacuum improvesmore » their crystallinity and prevents complete oxidation, so that Co-core/CoO-shell structure is preserved even after 120 days. The crystal structure of CoO shell in both samples is different from its bulk counterpart. Implications of such distorted CoO shells on exchange bias are discussed. Coating of Co nanoparticles with amorphous silica shell makes them resistant to oxidation, but ultimately modifies the crystal structure of both Co core and SiO2 shell.« less

  12. A roadmap to uranium ionic liquids: Anti-crystal engineering

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

    Yaprak, Damla; Spielberg, Eike T.; Bäcker, Tobias; Richter, Mark; Mallick, Bert; Klein, Axel; Mudring, Anja -Verena

    2014-04-15

    In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C4mim) cation. As dithiocarbamate ligands binding to the UO22+ unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim tomore » establish structure–property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. As a result, these materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery.« less

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    Press Room News, information and graphic resources from Fermilab and the world of high-energy physics: Press Releases All the news from Fermilab, from 1995 through today. Subscribe to the press release mailing list. Fermilab Fact Sheets Learn more about Fermilab's lasting scientific, social and economic impacts. Office of Communication Information, interviews with experts, speakers' bureau, background materials, emergency physics lessons for the on-deadline perplexed... Photo Archive High-res

  14. News Room

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

    Proud Legacy, Bold Future, Since 1943 News Room Your source for the latest news releases, fast facts, images and access to scores of scientists, engineers and other experts from Los Alamos National Laboratory. News Releases Science Briefs Photos Picture of the Week Publications Social Media Videos Fact Sheets James TenCate James TenCate elected Acoustical Society of America fellow TenCate's research focuses on nonlinear acoustics and elasticity, seismology and nonlinear imaging. 8/30/16 The

  15. Mixed-Salt Effects on the Ionic Conductivity of Lithium-Doped PEO-Containing Block Copolymers

    SciTech Connect (OSTI)

    Young, Wen-Shiue; Albert, Julie N.L.; Schantz, A. Benjamin; Epps, III, Thomas H.

    2012-10-10

    We demonstrate a simple, yet effective, mixed-salt method to increase the room temperature ionic conductivity of lithium-doped block copolymer electrolyte membranes by suppressing the crystalline phases in the conducting block. We examined a mixed-salt system of LiClO{sub 4} and LiN(SO{sub 2}CF{sub 3}){sub 2} (LiTFSI) doped into a lamellae-forming poly(styrene-b-ethylene oxide) (PS-PEO) diblock copolymer. The domain spacings, morphologies, thermal behavior, and crystalline phases of salt-doped PS-PEO samples were characterized, and the ionic conductivities of block copolymer electrolytes were obtained through ac impedance measurements. Comparing the ionic conductivity profiles of salt-doped PS-PEO samples at different mixed-salt ratios and total salt concentrations, we found that the ionic conductivity at room temperature can be improved by more than an order of magnitude when coinhibition of crystallite growth is promoted by the concerted behavior of the PEO:LiClO{sub 4} and PEO:LiTFSI phases. Additionally, we examined the influence of mixed-salt ratio and total salt concentration on copolymer energetics, and we found that the slope of the effective interaction parameter ({chi}{sub eff}) vs salt concentration in our lamellae-forming PS-PEO system was lower than that reported for a cylinder-forming PS-PEO system due to the balance between chain stretching and salt segregation in the PEO domains.

  16. Annealing behavior between room temperature and 2000 deg. C of deep level defects in electron-irradiated n-type 4H silicon carbide

    SciTech Connect (OSTI)

    Alfieri, G.; Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.

    2005-08-15

    The annealing behavior of irradiation-induced defects in 4H-SiC epitaxial layers grown by chemical-vapor deposition has been systematically studied by means of deep level transient spectroscopy (DLTS). The nitrogen-doped epitaxial layers have been irradiated with 15-MeV electrons at room temperature and an isochronal annealing series from 100 to 2000 deg. C has been performed. The DLTS measurements, which have been carried out in the temperature range from 120 to 630 K after each annealing step, revealed the presence of six electron traps located in the energy range of 0.45-1.6 eV below the conduction-band edge (E{sub c}). The most prominent and stable ones occur at E{sub c}-0.70 eV (labeled Z{sub 1/2}) and E{sub c}-1.60 eV(EH{sub 6/7}). After exhibiting a multistage annealing process over a wide temperature range, presumably caused by reactions with migrating defects, a significant fraction of both Z{sub 1/2} and EH{sub 6/7} (25%) still persists at 2000 deg. C and activation energies for dissociation in excess of 8 and {approx}7.5 eV are estimated for Z{sub 1/2} and EH{sub 6/7}, respectively. On the basis of these results, the identity of Z{sub 1/2} and EH{sub 6/7} is discussed and related to previous assignments in the literature.

  17. Constructing hierarchical interfaces: TiO2-supported PtFe-FeOx nanowires for room temperature CO oxidation

    SciTech Connect (OSTI)

    Zhu, Huiyuan; Wu, Zili; Dong, Su; Veith, Gabriel M.; Lu, Hanfeng; Zhang, Pengfei; Chai, Song -Hai; Dai, Sheng

    2015-08-05

    This is a report of a facile approach to constructing catalytic active hierarchical interfaces in one-dimensional (1D) nanostructure, exemplified by the synthesis of TiO2-supported PtFe–FeOx nanowires (NWs). The hierarchical interface, constituting atomic level interactions between PtFe and FeOx within each NW and the interactions between NWs and support (TiO2), enables CO oxidation with 100% conversion at room temperature. We identify the role of the two interfaces by probing the CO oxidation reaction with isotopic labeling experiments. Both the oxygen atoms (Os) in FeOx and TiO2 participate in the initial CO oxidation, facilitating the reaction through a redox pathway. Moreover, the intact 1D structure leads to the high stability of the catalyst. After 30 h in the reaction stream, the PtFe–FeOx/TiO2 catalyst exhibits no activity decay. These results provide a general approach and new insights into the construction of hierarchical interfaces for advanced catalysis.

  18. Constructing hierarchical interfaces: TiO2-supported PtFe-FeOx nanowires for room temperature CO oxidation

    SciTech Connect (OSTI)

    Zhu, Huiyuan; Wu, Zili; Dong, Su; Veith, Gabriel M; Lu, Hanfeng; Zhang, Pengfei; Chai, Songhai; Dai, Sheng

    2015-08-05

    This is a report of a facile approach to constructing catalytic active hierarchical interfaces in one-dimensional (1D) nanostructure, exemplified by the synthesis of TiO2-supported PtFeFeOx nanowires (NWs). The hierarchical interface, constituting atomic level interactions between PtFe and FeOx within each NW and the interactions between NWs and support (TiO2), enables CO oxidation with 100% conversion at room temperature. We identify the role of the two interfaces by probing the CO oxidation reaction with isotopic labeling experiments. Both the oxygen atoms (Os) in FeOx and TiO2 participate in the initial CO oxidation, facilitating the reaction through a redox pathway. Moreover, the intact 1D structure leads to the high stability of the catalyst. After 30 h in the reaction stream, the PtFeFeOx/TiO2 catalyst exhibits no activity decay. These results provide a general approach and new insights into the construction of hierarchical interfaces for advanced catalysis.

  19. Enhanced photoluminescence of SrWO{sub 4}:Eu{sup 3+} red phosphor synthesized by mechanochemically assisted solid state metathesis reaction method at room temperature

    SciTech Connect (OSTI)

    Peter, Anthuvan John Banu, I. B. Shameem

    2015-06-24

    Optically efficient europium activated alkaline earth metal tungstate nano phosphor (SrWO{sub 4}) with different doping concentrations have been synthesized by mechanochemically assisted solid state metathesis reaction at room temperature for the first time. The XRD and Raman spectra results indicated that the prepared powders exhibit a scheelite-type tetragonal structure. FTIR spectra exhibited a high absorption band situated at around 854 cm{sup −1}, which was ascribed to the W–O antisymmetric stretching vibrations into the [WO{sub 4}]{sup 2−} tetrahedron groups. Analysis of the emission spectra with different Eu{sup 3+} concentrations revealed that the optimum dopant concentration for SrWO{sub 4}: x Eu{sup 3+} phosphor is about 8 mol% of Eu{sup 3+}.The red emission intensity of the SSM prepared SrWO{sub 4}: 0.08Eu{sup 3+} phosphors are 2 times greater than that of the commercial Y{sub 2}O{sub 2}S: Eu{sup 3+} red phosphor prepared by the conventional solid state reaction method. All the results indicate that the phosphor is a promising red phosphor pumped by NUV InGaN chip for fabricating WLED.

  20. Growth of residual stress-free ZnO films on SiO{sub 2}/Si substrate at room temperature for MEMS devices

    SciTech Connect (OSTI)

    Singh, Jitendra; Akhtar, Jamil; Ranwa, Sapana; Kumar, Mahesh

    2015-06-15

    ZnO thick Stress relaxed films were deposited by reactive magnetron sputtering on 2”-wafer of SiO{sub 2}/Si at room temperature. The residual stress of ZnO films was measured by measuring the curvature of wafer using laser scanning method and found in the range of 0.18 x 10{sup 9} to 11.28 x 10{sup 9} dyne/cm{sup 2} with compressive in nature. Sputter pressure changes the deposition rates, which strongly affects the residual stress and surface morphologies of ZnO films. The crystalline wurtzite structure of ZnO films were confirmed by X-ray diffraction and a shift in (0002) diffraction peak of ZnO towards lower 2θ angle was observed with increasing the compressive stress in the films. The band gap of ZnO films shows a red shift from ∼3.275 eV to ∼3.23 eV as compressive stress is increased, unlike the stress for III-nitride materials. A relationship between stress and band gap of ZnO was derived and proposed. The stress-free growth of piezoelectric films is very important for functional devices applications.

  1. Resonant tunneling with high peak to valley current ratio in SiO{sub 2}/nc-Si/SiO{sub 2} multi-layers at room temperature

    SciTech Connect (OSTI)

    Chen, D. Y.; Sun, Y.; He, Y. J.; Xu, L.; Xu, J.

    2014-01-28

    We have investigated carrier transport in SiO{sub 2}/nc-Si/SiO{sub 2} multi-layers by room temperature current-voltage measurements. Resonant tunneling signatures accompanied by current peaks are observed. Carrier transport in the multi-layers were analyzed by plots of ln(I/V{sup 2}) as a function of 1/V and ln(I) as a function of V{sup 1/2}. Results suggest that besides films quality, nc-Si and barrier sub-layer thicknesses are important parameters that restrict carrier transport. When thicknesses are both small, direct tunneling dominates carrier transport, resonant tunneling occurs only at certain voltages and multi-resonant tunneling related current peaks can be observed but with peak to valley current ratio (PVCR) values smaller than 1.5. When barrier thickness is increased, trap-related and even high field related tunneling is excited, causing that multi-current peaks cannot be observed clearly, only one current peak with higher PVCR value of 7.7 can be observed. While if the thickness of nc-Si is large enough, quantum confinement is not so strong, a broad current peak with PVCR value as high as 60 can be measured, which may be due to small energy difference between the splitting energy levels in the quantum dots of nc-Si. Size distribution in a wide range may cause un-controllability of the peak voltages.

  2. Characterization of room temperature recrystallization kinetics in electroplated copper thin films with concurrent x-ray diffraction and electrical resistivity measurements

    SciTech Connect (OSTI)

    Treger, Mikhail; Noyan, I. C.; Witt, Christian; Cabral, Cyril; Murray, Conal; Jordan-Sweet, Jean; Rosenberg, Robert; Eisenbraun, Eric

    2013-06-07

    Concurrent in-situ four-point probe resistivity and high resolution synchrotron x-ray diffraction measurements were used to characterize room temperature recrystallization in electroplated Cu thin films. The x-ray data were used to obtain the variation with time of the integrated intensities and the peak-breadth from the Cu 111 and 200 reflections of the transforming grains. The variation of the integrated intensity and resistivity data with time was analyzed using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. For both 111-textured and non-textured electroplated Cu films, four-point probe resistivity measurements yielded shorter transformation times than the values obtained from the integrated intensities of the corresponding Cu 111 reflections. In addition, the JMAK exponents fitted to the resistivity data were significantly smaller. These discrepancies could be explained by considering the different material volumes from which resistivity and diffraction signals originated, and the physical processes which linked these signals to the changes in the evolving microstructure. Based on these issues, calibration of the resistivity analysis with direct structural characterization techniques is recommended.

  3. Heating remote rooms in passive solar buildings

    SciTech Connect (OSTI)

    Balcomb, J.D.

    1981-01-01

    Remote rooms can be effectively heated by convection through a connecting doorway. A simple steady-state equation is developed for design purposes. Validation of a dynamic model is achieved using data obtained over a 13-day period. Dynamic effects are investigated using a simulation analysis for three different cases of driving temperature; the effect is to reduce the temperature difference between the driving room and the remote room compared to the steady-state model. For large temperature swings in the driving room a strategy which uses the intervening door in a diode mode is effective. The importance of heat-storing mass in the remote room is investigated.

  4. Anion effects in the extraction of lanthanide 2-thenoyltrifluoroacetone complexes into an ionic liquid

    SciTech Connect (OSTI)

    Jensen, Mark P.; Beitz, James V.; Rickert, Paul G.; Borkowski, Marian; Laszak, Ivan; Dietz, Mark L.

    2012-07-01

    The extraction of trivalent lanthanides from an aqueous phase containing 1 M NaClO{sub 4} into the room temperature ionic liquid 1-butyl-3-methylimidazolium nonafluoro-1-butane sulfonate by the beta-diketone extractant 2-thenoyltrifluoroacetone (Htta) was studied. Radiotracer distribution, absorption spectroscopy, time-resolved laser-induced fluorescence spectroscopy, and X-ray absorption fine structure measurements point to the extraction of multiple lanthanide species. At low extractant concentrations, fully hydrated aqua cations of the lanthanides are present in the ionic liquid phase. As the extractant concentration is increased 1:2 and 1:3 lanthanide:tta species are observed. In contrast, 1:4 Ln:tta complexes were observed in the extraction of lanthanides by Htta into 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. (authors)

  5. High Temperature/Low Humidity Polymer Electrolytes Derived from...

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

    High TemperatureLow Humidity Polymer Electrolytes Derived from Ionic Liquids High TemperatureLow Humidity Polymer Electrolytes Derived from Ionic Liquids Presentation on High ...

  6. BeZnCdSe quantum-well ridge-waveguide laser diodes under low threshold room-temperature continuous-wave operation

    SciTech Connect (OSTI)

    Feng, Jijun; Akimoto, Ryoichi

    2015-10-19

    Low threshold current ridge-waveguide BeZnCdSe quantum-well laser diodes (LDs) have been developed by completely etching away the top p-type BeMgZnSe/ZnSe:N short-period superlattice cladding layer, which can suppress the leakage current that flows laterally outside of the electrode. The waveguide LDs are covered with a thick SiO{sub 2} layer and planarized with chemical-mechanical polishing and a reactive ion etching process. Room-temperature lasing under continuous-wave condition is achieved with the laser cavity formed by the cleaved waveguide facets coated with high-reflectivity dielectric films. For a 4 μm-wide green LD lasing around a wavelength of 535 nm, threshold current and voltage of 7.07 mA and 7.89 V are achieved for a cavity length of 300 μm, and the internal differential quantum efficiency, internal absorption loss, gain constant, and nominal transparency current density are estimated to be 27%, 4.09 cm{sup −1}, 29.92 (cm × μm)/kA and 6.35 kA/(cm{sup 2 }× μm), respectively. This compact device can realize a significantly improved performance with much lower threshold power consumption, which would benefit the potential application for ZnSe-based green LDs as light sources in full-color display and projector devices installed in consumer products such as pocket projectors.

  7. Ionic conductors for solid oxide fuel cells

    DOE Patents [OSTI]

    Krumpelt, Michael; Bloom, Ira D.; Pullockaran, Jose D.; Myles, Kevin M.

    1993-01-01

    An electrolyte that operates at temperatures ranging from 600.degree. C. to 800.degree. C. is provided. The electrolyte conducts charge ionically as well as electronically. The ionic conductors include molecular framework structures having planes or channels large enough to transport oxides or hydrated protons and having net-positive or net-negative charges. Representative molecular framework structures include substituted aluminum phosphates, orthosilicates, silicoaluminates, cordierites, apatites, sodalites, and hollandites.

  8. Partially fluorinated ionic compounds

    DOE Patents [OSTI]

    Han, legal representative, Amy Qi; Yang, Zhen-Yu

    2008-11-25

    Partially fluorinated ionic compounds are prepared. They are useful in the preparation of partially fluorinated dienes, in which the repeat units are cycloaliphatic.

  9. Room temperature magnetocaloric effect, critical behavior, and magnetoresistance in Na-deficient manganite La{sub 0.8}Na{sub 0.1}MnO{sub 3}

    SciTech Connect (OSTI)

    Khlifi, M. Dhahri, E.; Hlil, E. K.

    2014-05-21

    The La{sub 0.8}Na{sub 0.1}MnO{sub 3} oxide was prepared by the solid-state reaction and annealed in air. The X-ray diffraction data reveal that the sample is crystallized in a rhombohedral structure with R3{sup ¯}c space group. Magnetic study shows a second-order magnetic phase transition from ferromagnetic to paramagnetic state at the Curie temperature T{sub C} = 295 K. In addition, the magnetizations as a function of temperature and the magnetic field is used to evaluate the magnetic entropy change ΔS{sub M}. Then, we have deduced that the La{sub 0.8}Na{sub 0.1}MnO{sub 3} oxide has a large magnetocaloric effect at room temperature. Such effect is given by the maximum of the magnetic entropy change ΔS{sub Mmax} = 5.56, and by the Relative cooling power (RCP) factor which is equal to 235 under a magnetic field of 5 T. Moreover, the magnetic field dependence of the magnetic entropy change is used to determine the critical exponents β, γ, and δ which are found to be β = 0.495, γ = 1.083, and δ = 3.18. These values are consistent with the prediction of the mean field theory (β = 0.5, γ = 1, and δ = 3). Above all, the temperature dependence of electrical resistivity shows a metal–insulator transition at T{sub ρ}. The electrical resistivity decrease when we apply a magnetic field giving a magnetoresistance effect in the order of 60% at room temperature.

  10. Public Reading Room

    Office of Legacy Management (LM)

    By law, DOE must and will make a Public Reading Room available through site closure. Post-Closure: LM will maintain a Public Reading Room in accordance with EPA and Ohio EPA ...

  11. Molecular mechanisms of ionic liquid cytotoxicity probed by an integrated experimental and computational approach

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

    Yoo, Brian; Jing, Benxin; Jones, Stuart E.; Lamberti, Gary A.; Zhu, Yingxi; Shah, Jindal K.; Maginn, Edward J.

    2016-02-02

    Ionic liquids (ILs) are salts that remain liquid down to low temperatures, and sometimes well below room temperature. ILs have been called “green solvents” because of their extraordinarily low vapor pressure and excellent solvation power, but ecotoxicology studies have shown that some ILs exhibit greater toxicity than traditional solvents. A fundamental understanding of the molecular mechanisms responsible for IL toxicity remains elusive. Here we show that one mode of IL toxicity on unicellular organisms is driven by swelling of the cell membrane. Cytotoxicity assays, confocal laser scanning microscopy, and molecular simulations reveal that IL cations nucleate morphological defects in themore » microbial cell membrane at concentrations near the half maximal effective concentration (EC50) of several microorganisms. Lastly, cytotoxicity increases with increasing alkyl chain length of the cation due to the ability of the longer alkyl chain to more easily embed in, and ultimately disrupt, the cell membrane.« less

  12. Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for Room-temperature Nuclear Radiation Detectors

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

    Egarievwe, Stephen U.; Yang, Ge; Egarievwe, Alexander; Okwechime, Ifechukwude O.; Gray, Justin; Hales, Zaveon M.; Hossain, Anwar; Camarda, Guiseppe S.; Bolotnikov, Aleksey E.; James, Ralph B.

    2015-02-11

    Bridgman-grown cadmium zinc telluride (CdZnTe or CZT) and cadmium manganese telluride (CdMnTe or CMT) crystals often have Te inclusions that limit their performances as X-ray- and gamma-ray-detectors. We present here the results of post-growth thermal annealing aimed at reducing and eliminating Te inclusions in them. In a 2D analysis, we observed that the sizes of the Te inclusions declined to 92% during a 60-h annealing of CZT at 510 °C under Cd vapor. Further, tellurium inclusions were eliminated completely in CMT samples annealed at 570 °C in Cd vapor for 26 h, whilst their electrical resistivity fell by an ordermore » of 102. During the temperature-gradient annealing of CMT at 730 °C and an 18 °C/cm temperature gradient for 18 h in a vacuum of 10-5 mbar, we observed the diffusion of Te from the sample, causing a reduction in size of the Te inclusions. For CZT samples annealed at 700 °C in a 10 °C/cm temperature gradient, we observed the migration of Te inclusions from a low-temperature region to a high one at 0.022 μm/s. During the temperature-gradient annealing of CZT in a vacuum of 10-5 mbar at 570 °C and 30 °C/cm for 18 h, some Te inclusions moved toward the high-temperature side of the wafer, while other inclusions of the same size, i.e., 10 µm in diameter, remained in the same position. These results show that the migration, diffusion, and reaction of Te with Cd in the matrix of CZT- and CMT-wafers are complex phenomena that depend on certain conditions.« less

  13. Energy efficient microwave synthesis of mesoporous Ce0.5M0.5O2 (Ti, Zr, Hf) nanoparticles for low temperature CO oxidation in an ionic liquid – a comparative study

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

    Alammar, Tarek; Chow, Ying -Kit; Mudring, Anja -Verena

    2014-11-19

    Ce0.5M0.5O2 (M = Ti, Zr, Hf) nanoparticles have been successfully synthesized by microwave irradiation in the ionic liquid [C4mim][Tf2N] (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide). The morphology, crystallinity, and chemical composition of the obtained materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and N2–adsorption measurements. XRD and Raman spectroscopy analyses confirmed the formation of solid solutions with cubic fluorite structure. The catalytic activities of the Ce0.5M0.5O2 (M = Ti, Zr, Hf) nanoparticles were investigated in the low-temperature oxidation of CO. Ce0.5Zr0.5O2 nanospheres exhibit the best performance (100% conversion at 350 °C), followed by Ce0.5Hf0.5O2more » (55% conversion at 360 °C) and Ce0.5Ti0.5O2 (11% conversion at 350 °C). Heating the as-prepared Ce0.5Zr0.5O2 to 600 °C for extended time leads to a decrease in surface area and, as expected decreased catalytic activity. Depending on the ionic liquid the obtained Ce0.5Zr0.5O2 exhibits different morphologies, varying from nano-spheres in [C4mim][Tf2N] and [P66614][Tf2N] (P66614 = trishexyltetradecylphosphonium) to sheet-like assemblies in [C3mimOH][Tf2N] (C3mimOH = 1-(3-hydroxypropyl)-3-methylimidazolium). As a result, the microwave synthesis superiority to other heating methods like sonochemical synthesis and conventional heating was proven by comparative experiments where the catalytic activity of Ce0.5Zr0.5O2 obtained by alternate methods such as conventional heating was found to be poorer than that of the microwave-synthesised material.« less

  14. Room temperature magnetocaloric effect and refrigerant capacitance in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanotube arrays

    SciTech Connect (OSTI)

    Kumaresavanji, M. Sousa, C. T.; Pires, A.; Pereira, A. M.; Araujo, J. P.; Lopes, A. M. L.

    2014-08-25

    High aspect ratio La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanotube (NT) arrays have been synthesized using nitrates based sol-gel precursor by nanoporous anodized aluminum oxide template assisted method. Their phase purity and microstructures were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Magnetocaloric effect (MCE) of as prepared NTs was investigated by means of field dependence magnetization measurements. Significant magnetic entropy change, −△S{sub M} = 1.6 J/kg K, and the refrigerant capacitance, RC = 69 J/kg, were achieved near the transition temperature at 315 K for 5 T. For comparison, a bulk sample was also prepared using the same precursor solution which gives a value of −△S{sub M} = 4.2 J/kg K and a RC = 165 J/kg. Though the bulk sample exhibits higher △S{sub M} value, the NTs present an expanded temperature dependence of −△S{sub M} curves that spread over a broad temperature range and assured to be appropriate for active magnetic refrigeration. The diminutive MCE observed in manganite NTs is explained by the increased influence of surface sites of nanograins which affect the structural phase transition occurred by external magnetic field due to the coupling between magnetism and the lattice in manganese perovskites. Our report paves the way for further investigation in 1D manganite nanostructured materials towards applications in such magnetic refrigeration technology or even on hyperthermia/drug delivery.

  15. One-step synthesis of lightly doped porous silicon nanowires in HF/AgNO{sub 3}/H{sub 2}O{sub 2} solution at room temperature

    SciTech Connect (OSTI)

    Bai, Fan; State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 ; Li, Meicheng; Su Zhou Institute, North China Electric Power University, Suzhou 215123 ; Song, Dandan; Yu, Hang; Jiang, Bing; Li, Yingfeng

    2012-12-15

    One-step synthesis of lightly doped porous silicon nanowire arrays was achieved by etching the silicon wafer in HF/AgNO{sub 3}/H{sub 2}O{sub 2} solution at room temperature. The lightly doped porous silicon nanowires (pNWs) have circular nanopores on the sidewall, which can emit strong green fluorescence. The surface morphologies of these nanowires could be controlled by simply adjusting the concentration of H{sub 2}O{sub 2}, which influences the distribution of silver nanoparticles (Ag NPs) along the nanowire axis. A mechanism based on Ag NPs-induced lateral etching of nanowires was proposed to explain the formation of pNWs. The controllable and widely applicable synthesis of pNWs will open their potential application to nanoscale photoluminescence devices. - Graphical abstract: The one-step synthesis of porous silicon nanowire arrays is achieved by chemical etching of the lightly doped p-type Si (100) wafer at room temperature. These nanowires exhibit strong green photoluminescence. SEM, TEM, HRTEM and photoluminescence images of pNWs. The scale bars of SEM, TEM HRTEM and photoluminescence are 10 {mu}m, 20 nm, 10 nm, and 1 {mu}m, respectively. Highlights: Black-Right-Pointing-Pointer Simple one-step synthesis of lightly doped porous silicon nanowire arrays is achieved at RT. Black-Right-Pointing-Pointer Etching process and mechanism are illustrated with etching model from a novel standpoint. Black-Right-Pointing-Pointer As-prepared porous silicon nanowire emits strong green fluorescence, proving unique property.

  16. Complex Capacitance Scaling in Ionic Liquids-Filled Nanopores

    SciTech Connect (OSTI)

    Sumpter, Bobby G

    2011-01-01

    Recent experiments have shown that the capacitance of subnanometer pores increases anomalously as the pore width decreases, thereby opening a new avenue for developing supercapacitors with enhanced energy density. However, this behavior is still subject to some controversy since its physical origins are not well understood. Using atomistic simulations, we show that the capacitance of slit-shaped nanopores in contact with room-temperature ionic liquids exhibits a U-shaped scaling behavior in pores with widths from 0.75 to 1.26 nm. The left branch of the capacitance scaling curve directly corresponds to the anomalous capacitance increase and thus reproduces the experimental observations. The right branch of the curve indirectly agrees with experimental findings that so far have received little attention. The overall U-shaped scaling behavior provides insights on the origins of the difficulty in experimentally observing the pore-width-dependent capacitance. We establish a theoretical framework for understanding the capacitance of electrical double layers in nanopores and provide mechanistic details into the origins of the observed scaling behavior. The framework highlights the critical role of 'ion solvation' in controlling pore capacitance and the importance of choosing anion/cation couples carefully for optimal energy storage in a given pore system.

  17. Complex Capacitance Scaling in Ionic Liquids-filled Nanopores

    SciTech Connect (OSTI)

    Qiao, Rui; Huang, Jingsong; Meunier, Vincent; Sumpter, Bobby G; Peng, Wu

    2011-01-01

    Recent experiments have shown that the capacitance of sub-nanometer pores increases anomalously as the pore width decreases, thereby opening a new avenue for developing supercapacitors with enhanced energy density. However, this behavior is still subject to some controversy since its physical origins are not well understood. Using atomistic simulations, we show that the capacitance of slit-shaped nanopores in contact with room-temperature ionic liquids exhibits a U-shaped scaling behavior in pores with width from 0.75 to 1.26 nm. The left branch of the capacitance scaling curve directly corresponds to the anomalous capacitance increase and thus reproduces the experimental observations. The right branch of the curve indirectly agrees with experimental findings that so far have received little attention. The overall U-shaped scaling behavior provides insights on the origins of the difficulty in experimentally observing the pore-width dependent capacitance. We establish a theoretical framework for understanding the capacitance of electrical double layers in nanopores and provide mechanistic details into the origins of the observed scaling behavior. The framework highlights the critical role of ion solvation in controlling pore capacitance and the importance of choosing anion/cation couples carefully for optimal energy storage in a given pore system.

  18. Super ionic conductive glass

    DOE Patents [OSTI]

    Susman, S.; Volin, K.J.

    Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  19. Super ionic conductive glass

    DOE Patents [OSTI]

    Susman, Sherman; Volin, Kenneth J.

    1984-01-01

    An ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A.sub.1+x D.sub.2-x/3 Si.sub.x P.sub.3-x O.sub.12-2x/3, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  20. Preparation and purification of ionic liquids and precursors

    DOE Patents [OSTI]

    Burrell, Anthony K.; Warner, Benjamin P.; McCleskey, T. Mark; Agrawal, Anoop

    2010-07-27

    Substantially pure ionic liquids and ionic liquid precursors were prepared. The substantially pure ionic liquid precursors were used to prepare substantially pure ionic liquids.

  1. Experimental determination of lead carbonate solubility at high ionic strengths: A Pitzer model description

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

    Xiong, Yongliang

    2015-05-06

    In this article, solubility measurements of lead carbonate, PbCO3(cr), cerussite, as a function of total ionic strengths are conducted in the mixtures of NaCl and NaHCO3 up to I = 1.2 mol•kg–1 and in the mixtures of NaHCO3 and Na2CO3 up to I = 5.2 mol•kg–1, at room temperature (22.5 ± 0.5 °C). The solubility constant (log Ksp) for cerussite, PbCO3(cr) = Pb2+ + CO32- was determined as –13.76 ± 0.15 (2σ) with a set of Pitzer parameters describing the specific interactions of PbCO3(aq), Pb(CO3)22-, and Pb(CO3)Cl– with the bulk-supporting electrolytes, based on the Pitzer model. The model developed inmore » this work can reproduce the experimental results including model-independent solubility values from the literature over a wide range of ionic strengths with satisfactory accuracy. The model is expected to find applications in numerous fields, including the accurate description of chemical behavior of lead in geological repositories, the modeling of formation of oxidized Pb–Zn ore deposits, and the environmental remediation of lead contamination.« less

  2. Methods of using ionic liquids having a fluoride anion as solvents

    DOE Patents [OSTI]

    Pagoria, Philip; Maiti, Amitesh; Gash, Alexander; Han, Thomas Yong; Orme, Christine; Fried, Laurence

    2011-12-06

    A method in one embodiment includes contacting a strongly hydrogen bonded organic material with an ionic liquid having a fluoride anion for solubilizing the strongly hydrogen bonded organic material; and maintaining the ionic liquid at a temperature of about 90.degree. C. or less during the contacting. A method in another embodiment includes contacting a strongly hydrogen bonded organic material with an ionic liquid having an acetate or formate anion for solubilizing the strongly hydrogen bonded organic material; and maintaining the ionic liquid at a temperature of less than about 90.degree. C. during the contacting.

  3. Room Temperature Ferrimagnetism and Ferroelectricity in Strained...

    Office of Scientific and Technical Information (OSTI)

    ... panel) at 300 K in total electron yield mode (TEY) after pulsing at 9.5 kOe for Filml. ... the phase right after poling shown in Figure 5d, d) reading again after 24 h (Figure 5e). ...

  4. Room temperature ferrimagnetism and ferroelectricity in strained...

    Office of Scientific and Technical Information (OSTI)

    Univ. of Cambridge, Cambridge (United Kingdom). Dept. of Materials Science Rutherford Appleton Lab., Didcot (United Kingdom). ISIS, Science and Technology Facilities Council ...

  5. Room temperature ferrimagnetism and ferroelectricity in strained...

    Office of Scientific and Technical Information (OSTI)

    Stanford Synchrotron Radiation Lightsource Texas A & M Univ., College Station, TX (United ... Additional Journal Information: Journal Volume: 24; Journal Issue: 47; Journal ID: ISSN ...

  6. Ionic liquids, electrolyte solutions including the ionic liquids, and energy storage devices including the ionic liquids

    SciTech Connect (OSTI)

    Gering, Kevin L.; Harrup, Mason K.; Rollins, Harry W.

    2015-12-08

    An ionic liquid including a phosphazene compound that has a plurality of phosphorus-nitrogen units and at least one pendant group bonded to each phosphorus atom of the plurality of phosphorus-nitrogen units. One pendant group of the at least one pendant group comprises a positively charged pendant group. Additional embodiments of ionic liquids are disclosed, as are electrolyte solutions and energy storage devices including the embodiments of the ionic liquid.

  7. Synthesis of Ionic Liquids - Energy Innovation Portal

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

    Synthesis of Ionic Liquids Ionic Liquids for Chemical Separation Processes Oak Ridge National Laboratory Contact ORNL About This Technology Technology Marketing Summary Chemical ...

  8. Structural phase transition, narrow band gap, and room-temperature ferromagnetism in [KNbO{sub 3}]{sub 1?x}[BaNi{sub 1/2}Nb{sub 1/2}O{sub 3??}]{sub x} ferroelectrics

    SciTech Connect (OSTI)

    Zhou, Wenliang; Yang, Pingxiong Chu, Junhao; Deng, Hongmei

    2014-09-15

    Structural phase transition, narrow band gap (E{sub g}), and room-temperature ferromagnetism (RTFM) have been observed in the [KNbO{sub 3}]{sub 1?x}[BaNi{sub 1/2}Nb{sub 1/2}O{sub 3??}]{sub x} (KBNNO) ceramics. All the samples have single phase perovskite structure, but exhibit a gradual transition behaviour from the orthorhombic to a cubic structure with the increase of x. Raman spectroscopy analysis not only corroborates this doping-induced change in normal structure but also shows the local crystal symmetry for x ? 0.1 compositions to deviate from the idealized cubic perovskite structure. A possible mechanism for the observed specific changes in lattice structure is discussed. Moreover, it is noted that KBNNO with compositions x?=?0.10.3 have quite narrow E{sub g} of below 1.5?eV, much smaller than the 3.2?eV band gap of parent KNbO{sub 3} (KNO), which is due to the increasing Ni 3d electronic states within the gap of KNO. Furthermore, the KBNNO materials present RTFM near a tetragonal to cubic phase boundary. With increasing x from 0 to 0.3, the magnetism of the samples develops from diamagnetism to ferromagnetism and paramagnetism, originating from the ferromagneticantiferromagnetic competition. These results are helpful in the deeper understanding of phase transitions, band gap tunability, and magnetism variations in perovskite oxides and show the potential role, such materials can play, in perovskite solar cells and multiferroic applications.

  9. Curvature Effect on the Capacitance of Electric Double Layers at Ionic Liquid/Onion-Like Carbon Interfaces

    SciTech Connect (OSTI)

    Feng, Guang; Jiang, Deen; Cummings, Peter T

    2012-01-01

    Recent experiments have revealed that onion-like carbons (OLCs) offer high energy density and charging/discharging rates when used as the electrodes in supercapacitors. To understand the physical origin of this phenomenon, molecular dynamics simulations were performed for a room-temperature ionic liquid near idealized spherical OLCs with radii ranging from 0.356 to 1.223 nm. We find that the surface charge density increases almost linearly with the potential applied on electric double layers (EDLs) near OLCs. This leads to a nearly flat shape of the differential capacitance versus the potential, unlike the bell or camel shape observed on planar electrodes. Moreover, our simulations reveal that the capacitance of EDLs on OLCs increases with the curvature or as the OLC size decreases, in agreement with experimental observations. The curvature effect is explained by dominance of charge overscreening over a wide potential range and increased ion density per unit area of electrode surface as the OLC becomes smaller.

  10. Correlating mechanical properties and anti-wear performance of tribofilms formed by ionic liquids, ZDDP and their combinations

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

    Landauer, Alexander K.; Barnhill, William C.; Qu, Jun

    2016-03-10

    Here we examine the elasticity, hardness, and resistance-to-plastic-deformation (P/S2) measured via nanoindentation of several tribofilms and correlates these properties to friction and wear behavior. The tribofilms were generated by ball-on-plate reciprocating sliding lubricated by a base oil containing an ionic liquid, phosphonium-organophosphate or ammonium-organophosphate, zinc dialkyldithiophosphate (ZDDP), or combination of IL and ZDDP. Nanoindentation was conducted at room and elevated temperatures. While there seems little correlation between the tribofilm hardness and tribological behavior, a higher modulus generally leads to better friction and wear performance. Interestingly, a lower P/S2 ratio tends to reduce friction and improve wear protection, which is inmore » an opposite trend as reported for bulk materials. Ultimately, this is likely attributable to the dynamic, self-healing characteristics of tribofilms.« less