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Sample records for subs apps subs

  1. Mechanism of superconductivity in Yb sub 1 sub - sub x Ca sub x (Ba sub 0 sub . sub 8 Sr sub O sub . sub 2) sub 2 Cu sub 3 O sub 6 sub + subdelta

    CERN Document Server

    Anvekar, T S; Sarode, P R; Kamat-Dalal, V N; Narlikar, Anant V

    2002-01-01

    EXAFS, X-ray Rietveld refinement and infra-red absorption measurements have been made on Yb sub 1 sub - sub x Ca sub x (Ba sub 0 sub . sub 8 Sr sub 0 sub . sub 2) sub 2 Cu sub 3 O sub 6 sub + subdelta in order to understand the effect of Ca doping on the local structure of planar Cu ion. The study indicates that restoration of superconductivity is due to oxidation of copper ions in the CuO sub 2 planes. (author)

  2. Density of localized states in (Pb sub 0 sub . sub 7 sub 8 Sn sub 0 sub . sub 2 sub 2) sub 0 sub . sub 9 sub 5 In sub 0 sub . sub 0 sub 5 Te solid solution

    CERN Document Server

    Nemov, S A; Potapova, D A

    2001-01-01

    Hopping electric conductivity and thermoelectromotive force have been measured in Pb sub 0 sub . sub 7 sub 8 Sn sub 0 sub . sub 2 sub 2 Te with 5 at.% In and the supplementary doping with donor impurity Cl. Experimental data have been compared with results of the supplementary doping by the acceptor impurity Tl. At temperatures 150 K and higher, the positive thermoelectromotive force coefficient changes its sign becoming negative at a sufficient content of both donors and acceptors. An analysis of the dependence of thermoelectromotive force on the content of supplementary donors and acceptors gives the energy dependence of the density of localized states of indium. This function is essentially unmonotonous

  3. Structure and magnetostriction of Nd sub 0 sub . sub 6 sub 7 Tb sub 0 sub . sub 3 sub 3 (Co sub 1 sub - sub x Fe sub x) sub 2 compounds

    CERN Document Server

    Ouyang, Z W; Yang, H F; Liu, W F; Liu, G Y; Feng, X M; Liang, J K

    2003-01-01

    The crystal structure, Curie temperature and magnetostriction of compounds with the formula Nd sub 0 sub . sub 6 sub 7 Tb sub 0 sub . sub 3 sub 3 (Co sub 1 sub - sub x Fe sub x) sub 2 were investigated by x-ray powder diffraction and magnetic measurements. It is revealed that the substitution of Fe for Co destabilizes the cubic Laves phase Nd sub 0 sub . sub 6 sub 7 Tb sub 0 sub . sub 3 sub 3 (Co,Fe) sub 2. The maximum substitution of Fe for Co is about 0.57. The lattice constant of the Nd sub 0 sub . sub 6 sub 7 Tb sub 0 sub . sub 3 sub 3 (Co,Fe) sub 2 phase increases with x increasing from x = 0.0 to 0.6, then remains almost unchanged from x = 0.6 to 0.9. The Curie temperature exhibits a variation similar to that of the lattice constant with the Fe concentration. A spin reorientation is observed, which can be understood on the basis of the two-sublattice model. The spontaneous magnetostriction constant lambda sub 1 sub 1 sub 1 shows a maximum value of 1.7 x 10 sup - sup 3 at x = 0.4. The temperature depende...

  4. C60 and U ion irradiation of Gd<sub>2sub>TixZr>2-xsub>O>7sub> pyrochlore

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiaming; Toulemonde, Marcel; Lang, Maik; Costantini, Jean Marc; Della-Negra, Serge; Ewing, Rodney C.

    2015-08-01

    Gd<sub>2sub>TixZr>2-xsub>O>7sub> (x = 0 to 2) pyrochlore was irradiated by 30 MeV C<sub>60sub> clusters, which provide an extremely high ionizing energy density. Here, high-resolution transmission electron microscopy revealed a complex ion-track structure in Gd<sub>2sub>Ti>2sub>O>7sub> and Gd<sub>2sub>TiZrO>7sub>, consisting of an amorphous core and a shell of a disordered, defect-fluorite structure.

  5. The transport properties in strongly correlated BaCo sub 0 sub . sub 9 Ni sub 0 sub . sub 1 S sub 1 sub . sub 8 sub 7

    CERN Document Server

    Zhou, J S; Goodenough, J B

    2002-01-01

    Layered tetragonal BaCo sub 0 sub . sub 9 Ni sub 0 sub . sub 1 S sub 2 contains high-spin Co(II) in octahedral sites and is an insulator. Hole doping by introducing sulfur vacancies results in a polaronic conductivity and produces a transition to a monoclinic metallic phase with a nearly isotropic conductivity. Pressure P >=1.5 kbar suppresses the monoclinic phase and at P >=10 kbar the high temperature tetragonal phase is transferred to an isostructural metallic phase containing low-spin Co(II). The single-crystal resistivity along the c-axis and in the a-b plane of high-pressure, tetragonal BaCo sub 0 sub . sub 9 Ni sub 0 sub . sub 1 S sub 1 sub . sub 8 sub 7 is shown to be highly anisotropic and to resemble that of the overdoped superconductive system La sub 2 sub sub - sub x Sr sub x CuO sub 4.

  6. Structural and magnetic properties and superconductivity in Ba(Fe<sub>1-xsub>TMx)>2sub>As>2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Thaler, Alexander [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    We studied the effects on structural and magnetic phase transitions and the emergence of superconductivity in transition metal substituted BaFe<sub>2sub>As>2sub>. We grew four series of Ba(Fe<sub>1-xsub>TM>2sub>)>2sub>As>2sub> (TM=Ru, Mn, Co+Cr and Co+Mn) and characterized them by crystallographic, magnetic and transport measurements. We also subjected Ba(Fe<sub>1-xsub>Crx)>2sub>As>2sub> and Ba(Fe<sub>1-xsub>Cox)>2sub>As>2sub> to heat treatment to explore what changes might be induced.

  7. Noggin and BMP4 co-modulate adult hippocampal neurogenesis in the APP{sub swe}/PS1{sub {Delta}E9} transgenic mouse model of Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jun [Department of Medical Genetics, Third Military Medical University, Chongqing 400038 (China); Department of Physiology, Third Military Medical University, Chongqing 400038 (China); Song, Min; Wang, Yanyan [Department of Medical Genetics, Third Military Medical University, Chongqing 400038 (China); Fan, Xiaotang [Department of Histology and Embryology, Third Military Medical University, Chongqing 400038 (China); Xu, Haiwei, E-mail: haiweixu2001@yahoo.com.cn [Department of Physiology, Third Military Medical University, Chongqing 400038 (China); Bai, Yun, E-mail: baiyungene@gmail.com [Department of Medical Genetics, Third Military Medical University, Chongqing 400038 (China)

    2009-07-31

    In addition to the subventricular zone, the dentate gyrus of the hippocampus is one of the few brain regions in which neurogenesis continues into adulthood. Perturbation of neurogenesis can alter hippocampal function, and previous studies have shown that neurogenesis is dysregulated in Alzheimer disease (AD) brain. Bone morphogenetic protein-4 (BMP4) and its antagonist Noggin have been shown to play important roles both in embryonic development and in the adult nervous system, and may regulate hippocampal neurogenesis. Previous data indicated that increased expression of BMP4 mRNA within the dentate gyrus might contribute to decreased hippocampal cell proliferation in the APP{sub swe}/PS1{sub {Delta}E9} mouse AD model. However, it is not known whether the BMP antagonist Noggin contributes to the regulation of neurogenesis. We therefore studied the relative expression levels and localization of BMP4 and its antagonist Noggin in the dentate gyrus and whether these correlated with changes in neurogenesis in 6-12 mo old APP{sub swe}/PS1{sub {Delta}E9} transgenic mice. Bromodeoxyuridine (BrdU) was used to label proliferative cells. We report that decreased neurogenesis in the APP/PS1 transgenic mice was accompanied by increased expression of BMP4 and decreased expression of Noggin at both the mRNA and protein levels; statistical analysis showed that the number of proliferative cells at different ages correlated positively with Noggin expression and negatively with BMP4 expression. Intraventricular administration of a chimeric Noggin/Fc protein was used to block the action of endogenous BMP4; this resulted in a significant increase in the number of BrdU-labeled cells in dentate gyrus subgranular zone and hilus in APP/PS1 mice. These results suggest that BMP4 and Noggin co-modulate neurogenesis.

  8. Magnetic signature of charge ordering in Li[Mn sub 1 sub . sub 9 sub 6 Li sub 0 sub . sub 0 sub 4]O sub 4 and Li sub 0 sub . sub 2 [Mn sub 1 sub . sub 9 sub 6 Li sub 0 sub . sub 0 sub 4]O sub 4

    CERN Document Server

    Verhoeven, V W J; Mulder, F M

    2002-01-01

    The stoichiometric compound LiMn sub 2 O sub 4 is known to show charge ordering with well-defined Mn sup 3 sup + and Mn sup 4 sup + sites just below room temperature (RT). Above RT the electrons are hopping rapidly between sites. For lithium-ion batteries the material Li[Mn sub 1 sub . sub 9 sub 6 Li sub 0 sub . sub 0 sub 4]O sub 4 is technologically relevant. Due to the small amount of Li on the Mn site, the low-T regular ordering of the Mn charge appears to be destroyed completely, as is evidenced by neutron diffraction in the magnetically ordered state. However, the charges are still fixed in an irregular fashion, as can also be deduced from sup 7 Li nuclear magnetic resonance measurements. In the lithium-extracted compound Li sub 0 sub . sub 2 [Mn sub 1 sub . sub 9 sub 6 Li sub 0 sub . sub 0 sub 4]O sub 4 , predominantly Mn sup 4 sup + is present. Neutron diffraction in the magnetically ordered state shows a well-defined antiferromagnetic ordering, with doubling of the unit cell in three directions. Clear...

  9. Two anhydrous zeolite X crystal structures, Pd sub 1 sub 8 Tl sub 5 sub 6 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4 and Pd sub 2 sub 1 Tl sub 5 sub 0 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4

    CERN Document Server

    Yoon, B Y; Lee, S H; Kim, Y

    2001-01-01

    The crystal structures of fully dehydrated Pd sup 2 sup + - and Tl sup + -exchanged zeolite X, Pd sub 1 sub 8 Tl sub 5 sub 6 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4 (Pd sub 1 sub 8 Tl sub 5 sub 6 X, a = 24.935(4) A) and Pd sub 2 sub 1 Tl sub 5 sub 0 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4 (Pd sub 2 sub 1 Tl sub 5 sub 0 -X, a = 24.914(4) A), have been determined by single-crystal X-ray diffraction methods in the cubic space group Fd3 at 21(1) .deg. C. The crystals were prepared using an exchange solution that had a Pd(NH sub 3) sub 4 Cl sub 2 : TINO sub 3 mole ratio of 50 : 1 and 200 : 1, respectively, with a total concentration of 0.05 M for 4 days. After dehydration at 360 .deg. C and 2 x 10 sup - sup 6 Torr in flowing oxygen for 2 days, the crystals were evacuated at 21(1) .deg. C for 2 hours. They were refined to the final error indices R sub 1 = 0.045 and R sub 2 = 0.038 with 344 reflections for Pd sub 1 sub 8 Tl sub 5 sub 6 -X, and R sub 1 = 0.043 and R sub 2 = 0.045 with ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1982-09-01

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

  11. Synthesis and characterisation of La sub 4 BaCu sub 5 O sub 1 sub 3 sub + subdelta, La sub 8 sub - sub x Sr sub x Cu sub 8 O sub 2 sub 0 sub - subdelta, REBaCo sub 2 O sub 6 sub - subdelta and related phases

    CERN Document Server

    Anderson, P S

    2001-01-01

    BaCu sub 5 sub - sub x Zn sub x O sub 1 sub 3 sub + subdelta a solid solution range of 0 <= x <= 0 centre dot 47(1) was determined from quantitative EPMA. Attempts to prepare La sub 4 BaCu sub 5 sub - sub x M sub x O sub 1 sub 3 sub + subdelta (M Mg, Al, Cr, Mn) were unsuccessful. The La-rich end of the compositional series La sub 8 sub - sub x Sr sub x Cu sub 8 O sub 2 sub 0 sub - subdelta was investigated, a tetragonal solid solution: 1 centre dot 38(2) <= x <= 2 centre dot 4(1) was prepared. This range is wider than previously reported, possibly due to longer reaction times used. An orthorhombic stoichiometric phase with composition La sub 6 subcentre dot sub 9 sub 0 Sr sub 1 subcentre dot sub 1 sub 0 Cu sub 8 O sub 2 sub 0 sub - subdelta was prepared in air at 1000 deg C. In the literature, it was claimed that it could be synthesised only in O sub 2 above 1020 deg C. La sub 6 subcentre dot sub 4 Sr sub 1 subcentre dot sub 6 Cu sub 8 sub - sub y M sub y O sub 2 sub 0 sub - subdelta (M = Ni, Co,...

  12. Lithium ion conductivity in Li <sub>2sub> S–P <sub>2sub> S <sub>5sub> glasses – building units and local structure evolution during the crystallization of superionic conductors Li <sub>3sub> PS <sub>4sub> , Li <sub>7sub> P <sub>3sub> S <sub>11sub> and Li <sub>4sub> P <sub>2sub> S <sub>7sub>

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Christian [Institute of Physical Chemistry; Justus-Liebig-University Giessen; D-35392 Giessen; Germany; Weber, Dominik A. [Institute of Physical Chemistry; Justus-Liebig-University Giessen; D-35392 Giessen; Germany; Sedlmaier, Stefan J. [BELLA – Batteries and Electrochemistry Laboratory; Institute of Nanotechnology; Karlsruhe Institute of Technology; D-76344 Eggenstein-Leopoldshafen; Germany; Indris, Sylvio [Institute for Applied Materials; Karlsruhe Institute of Technology; D-76344 Eggenstein-Leopoldshafen; Germany; Culver, Sean P. [Institute of Physical Chemistry; Justus-Liebig-University Giessen; D-35392 Giessen; Germany; Walter, Dirk [Institute of Occupational Medicine; Laboratories of Chemistry and Physics; Justus-Liebig-University Giessen/University Hospital Giessen/Marburg; D-35392 Giessen; Germany; Janek, Jürgen [Institute of Physical Chemistry; Justus-Liebig-University Giessen; D-35392 Giessen; Germany; BELLA – Batteries and Electrochemistry Laboratory; Zeier, Wolfgang G. [Institute of Physical Chemistry; Justus-Liebig-University Giessen; D-35392 Giessen; Germany

    2017-01-01

    The local structure phase diagram of (Li<sub>2sub>S)x(P>2sub>S>5sub>)>100-xsub>thiophosphates derived from pair distribution function crystallization experiments.

  13. Magnetic, Caloric and Crystallographic Properties of Dy<sub>5sub>(SixGe>1-xsub>)>4 sub> Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ivchenko, Vitaliy Vladislavovich [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    Polycrystals of the intermetallic compound of the Dy<sub>5sub>(SixGe>1-xsub>)>4 sub> system, where x = 0, 0.25, 0.5, 0.625, 0.675, 0.725, 0.75, 0.775, 0.825, 0.875, and 1, have been prepared by electric-arc-melting on water-cooled copper hearth in an argon atmosphere. A study of phase relationships and crystallography in the pseudobinary system Dy<sub>5sub>(SixGe>1-xsub>)>4 sub> using X-ray powder diffraction data and optical metallography was completed. It revealed that silicides in the composition range from 0.825 to 1 crystallize in the Gd<sub>5sub>Si>4sub>-type crystal structure: germanides in the composition range from 0 to 0.625 crystallize in the Sm<sub>5sub>Ge>4sub>-type structure, and alloys with intermediate composition range from 0.675 to 0.775 crystallize in the monoclinic Gd<sub>5sub>Si>2sub>Ge>2sub>-type structure. The -ΔS<sub>m> values were determined from magnetization measurements for 7 alloys. The alloys with a monoclinic crystal structure which belong to an intermediate phase region have large MCE value, which exceeds those observed in the other two phase regions by 300 to 500%. The nature of the observed magnetic and structural transformations in the Dy<sub>5sub>(SixGe>1-xsub>)>4 sub> system seems to be similar with those reported for the Gd<sub>5sub>(SixGe>1-xsub>)>4 sub> system. However, the interval and concentration range of three different phase regions in the Dy<sub>5sub>(SixGe>1-xsub>)>4 sub> system are different from that observed in Gd-based alloys. A non-collinear ordering of magnetic moments at low temperature was observed for the alloys with monoclinic crystal structure. The Dy<sub>5sub>Si>3sub>Ge alloy exhibited FM phase transition below Curie temperature. A series of magnetic transitions were observed at low temperature in the Dy<sub>5sub>(SixGe>1-xsub>)

  14. Magnetic, Caloric and Crystallographic Properties of Dy<sub>5sub>(SixGe>1-xsub>)>4sub> Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ivchenko, Vitaliy Vladislavovich [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    A study of a series of Dy<sub>5sub>(SixGe>1-xsub>)>4sub> alloys using dc and ac magnetic susceptibility, magnetization, heat capacity, and x-ray powder diffraction techniques revealed that the variation of the magnetic properties and crystal structures with composition is similar to that observed in the Gd<sub>5sub>(SixGe>1-xsub>)>4sub> system, except that the magnetic ordering temperatures are lower. The magnetic phase transition temperatures vary from ~ 46K (Dy<sub>5sub>Ge>4sub>) to ~ 137K (Dy<sub>5sub>Si>4sub>). The intermediate ternary phase Dy<sub>5sub>Si>3sub>Ge undergoes a first order magnetic phase transition at ~ 65K. The value of magnetic entropy change for this composition is quite large (-34J/kgK for magnetic field change from 0 to 50kOe), compared to the values for the two end members (-7 J/kgK for Dy<sub>5sub>Ge>4sub> and -12.5J/kgK for Dy<sub>5sub>Si>4sub>). The magnetization and ac susceptibility measurements showed that alloys with monoclinic crystal structure have a non-collinear ordering of the magnetic moments at low temperatures. The alloy Dy<sub>5sub>Si>3sub>Ge appears to exhibit a FM phase transition below the Curie temperature at 65K. Also a series of critical fields are observed at low temperature during magnetization vs magnetic field measurements in all of the Dy<sub>5sub>(SixGe>1-xsub>)>4sub> alloys regardless type of crystal structure. The Dy<sub>5sub>(SixGe>1-xsub>)>4sub> alloys, where 0.67≤x≤1, may be useful magnetic refrigerant materials in the ~50 to ~160K temperature range.

  15. The effects of annealing temperature on the magnetic properties of Fe sub 7 sub 5 sub . sub 5 Zr sub 8 sub . sub 3 N sub 1 sub 6 sub . sub 2 /SiO sub 2 multilayer thin films

    CERN Document Server

    Kim, T S; Kim, C O; Chung, H S; Hwang, Y

    1999-01-01

    [Fe sub 7 sub 5 sub . sub 5 Zr sub 8 sub . sub 3 N sub 1 sub 6 sub . sub 2 (800 A)/SiO sub 2 (250 A)] sub 1 sub 0 multilayer thin films were fabricated by using an rf magnetron reactive sputtering method. The saturation magnetic flux density and the coercive force were measured as functions of the annealing temperature. The effective permeability at high frequencies and the thermal stability were also examined. The magnetic properties of the [Fe sub 7 sub 5 sub . sub 5 Zr sub 8 sub . sub 3 N sub 1 sub 6 sub . sub 2 (800 A)/SiO sub 2 (250 A)] sub 1 sub 0 multilayer thin films showed a saturation flux density of 1.08 T, a coercive force of 0.41 Oe, and an effective permeability of about 4000 at 1 MHz. The observed good magnetic softness is attributed to the prohibition of the growth of alpha-Fe grains due to the precipitation of nanocrystalline ZrN particles. The sizes of the alpha-Fe grains and the nanocrystalline ZrN particles were 40 approx 50 A and 10 approx 15 A, respectively. The effective permeability of...

  16. Ferromagnetic resonance of Co sub 1 sub 0 sub 0 sub - sub x Hf sub x thin films

    CERN Document Server

    Baek, J S; Lee, S H; Lim, W Y

    1999-01-01

    In order to examine the temperature dependence of the magnetic properties in Co sub 1 sub 0 sub 0 sub - sub x Hf sub x (x=16, 24, 32 at.%) thin films, such as the effective magnetization M sub e sub f sub f , the spectroscopic splitting factor g, the exchange stiffness constant A, and the surface magnetic anisotropy constant K sub s , we carried out ferromagnetic resonance (FMR) experiments in the temperature range of 113 approx 293 K. Spin wave modes, as well as the surface modes, appeared in the Co sub 8 sub 4 Hf sub 1 sub 6 and the Co sub 7 sub 6 Hf sub 2 sub 4 thin films. In the Co sub 6 sub 8 Hf sub 3 sub 2 thin films, however, the spin wave modes appeared only below 233 K. The M sub e sub f sub f and the A increased slightly with decreasing temperature down to 113 K for all samples, but the g were almost constant, regardless of the temperature. The surface magnetic anisotropy constant K sub s sub 1 of the film-air interface and the surface magnetic anisotropy constant K sub s sub 2 of the film-substrate...

  17. Growth and characterization of Ni sub x Cu sub 1 sub - sub x alloy films, Ni sub x Cu sub 1 sub - sub x /Ni sub y Cu sub 1 sub - sub y multilayers, and nanowires

    CERN Document Server

    Kazeminezhad, I

    2001-01-01

    few nm and the full width of the wire. The actual length and diameter of the wires were measured to be approx 5 mu m and (80+-5)nm respectively. The chemical compositions of the nanowires were obtained by EDX analysis. sub 4 sub 8 and Ni sub 0 sub . sub 6 sub 2 CU sub 0 sub . sub 3 sub 8 films showed that they become much more strongly ferromagnetic at low temperatures. Evidence for blocked -superparamagnetic behaviour above a blocking temperature (T sub B) of the films was obtained from zero-field-cooled (ZFC) and field-cooled (FC) magnetic susceptibility measurements. Ni sub x Cu sub 1 sub - sub x /Ni sub y Cu sub 1 sub - sub y alloy/alloy multilayer films with short repeat distance were successfully fabricated using this method. Up to third order satellite peaks observed in HAXRD showed that the interface is sharp. Room temperature longitudinal magnetoresistance measurements showed that Ni sub x Cu sub 1 sub - sub x /Ni sub y Cu sub 1 sub - sub y multilayers with certain layer thicknesses and compositions ...

  18. CO Oxidation and Subsequent CO<sub>2sub> Chemisorption on Alkaline Zirconates: Li<sub>2sub> ZrO<sub>3sub> and Na<sub>2sub> ZrO<sub>3sub>

    Energy Technology Data Exchange (ETDEWEB)

    Alcántar-Vázquez, Brenda; Duan, Yuhua; Pfeiffer, Heriberto

    2016-09-21

    Here, two different alkaline zirconates (Li<sub>2sub>ZrO>3sub> and Na<sub>2sub>ZrO>3sub>) were studied as possible bifunctional catalytic-captor materials for CO oxidation and the subsequent CO<sub>2sub> chemisorption process. Initially, CO oxidation reactions were analyzed in a catalytic reactor coupled to a gas chromatograph, using Li<sub>2sub>ZrO>3sub> and Na<sub>2sub>ZrO>3sub>, under different O<sub>2sub> partial flows. We found results clearly showed that Na<sub>2sub>ZrO>3sub> possesses much better catalytic properties than Li<sub>2sub>ZrO>3sub>. After the CO-O<sub>2sub> oxidation catalytic analysis, CO2 chemisorption process was analyzed by thermogravimetric analysis, only for the Na<sub>2sub>ZrO>3sub> ceramic. The results confirmed that Na<sub>2sub>ZrO>3sub> is able to work as a bifunctional material (CO oxidation and subsequent CO<sub>2sub> chemisorption), although the kinetic CO<sub>2sub> capture process was not the best one under the physicochemical condition used in this case. For Na<sub>2sub>ZrO>3sub>, the best CO conversions were found between 445 and 580 °C (100%), while Li<sub>2sub>ZrO>3sub> only showed a 35% of efficiency between 460 and 503 °C. However, in the Na<sub>2sub>ZrO>3sub> case, at temperatures higher than 580 °C its catalytic activity gradually decreases as a result of CO<sub>2sub> capture process. Finally, all these experiments were compared and supported with theoretical thermodynamic data.

  19. Raman spectra of the solid-solution between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 and RbCa sub 2 Nb sub 3 O sub 1 sub 0

    CERN Document Server

    Kim, H J; Yun, H S

    2001-01-01

    A site preference of niobium atom in Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) and RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0), which are the solid-solutions between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 are RbCa sub 2 Nb sub 3 O sub 1 sub 0 , has been investigated by Raman spectroscopy. The Raman spectra of Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) gave an evidence that niobium atoms substituted for titanium atoms preferably occupy the highly distorted outer octahedral sites rather than the central ones in triple-octahedral perovskite layers. In contrast, the Raman spectra of RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0) showed no clear information for the cationic arrangement in perovskite slabs. This difference indicated that a site preference of niobium atoms is observed onl...

  20. Crystal structures of Ni sup 2 sup + -and Tl sup + -exchanged zeolite X, Ni sub 1 sub 7 Tl sub 5 sub 8 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4 and Ni sub 1 sub 2 Tl sub 6 sub 8 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4

    CERN Document Server

    Song, M K; Kim, Y

    2001-01-01

    The crystal structures of fully dehydrated Ni sup 2 sup + - and Tl sup + -exchanged zeolite X (Ni sub 1 sub 7 Tl sub 5 sub 8 -X, and Ni sub 1 sub 2 Tl sub 6 sub 8 -X; X=Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4) have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1) .deg. C (a=24.380(4) A, 24.660(4) A, respectively). Their structures have been refined to the final error indices R sub 1 =0.037 and R sub 2 =0.043 with 485 reflections, and R sub 1 =0.039 and R sub 2 =0.040 with 306 reflections, respectively, for which I>3 sigma(I). In Ni sub 1 sub 7 Tl sub 5 sub 8 -X, 17 Ni sup 2 sup + ions per unit cell were found at only two sites: 15 at site I at the center of the hexagonal prism (Ni-O=2.203(9) A). and the remaining 2 at site II near single six-oxygen rings in the supercage (Ni-O=2.16(3) A). Fifty-eight Tl sup + ions were found at five crystallographic sites: 28 at site II (Tl-O=2.626(8) A, 2 at site I' in the sodalite cavity near the hexagonal ...

  1. Spin crossover at magnetic phase transformation in YBa sub 2 (Cu sub 1 sub - sub x Fe sub x) sub 3 O sub 7 sub+- subdelta superconductors

    CERN Document Server

    Lyubutin, I S

    2001-01-01

    It is established that all iron ions in the Cu1 and Cu2 local nodes in the YBa sub 2 (Cu sub 0 sub . sub 9 sup 5 sup 7 Fe sub 0 sub . sub 1) sub 3 O sub 7 sub . sub 0 sub 1 superconducting compound with the T sub c = 31 K at the temperature below T sub m = 22 K become magneto-ordered. Thus, the magnetic order by the T < T sub m coexists with the superconductivity. It is determined through the Moessbauer spectroscopy method that the iron ions in the Cu2 (Fe2) nodes at the temperature T < T sub m are in the low-spin state (S 3/2 or 1/2), whereas the same quantity of the iron ions in the Cu1 (Fe1) nodes is in the Fe sup 3 sup + high-spin state (S = 5/2). By the magnetic transition near T sub m these ions change the spin values and transit form low-spin state to the high-spin one and vice versa. Control measurements on other samples of the YBa sub 2 (Cu sub 1 sub - sub x Fe sub x) sub 3 O sub 7 sub+- subdelta series confirm these conclusions

  2. Moessbauer study of Cu sub 0 sub . sub 8 Fe sub 2 sub . sub 2 O sub 4

    CERN Document Server

    Kim, S J; An, D H; Kang, K U; Baek, K S; Oak, H N

    2000-01-01

    Cu sub 0 sub . sub 8 Fe sub 2 sub . sub 2 O sub 4 has been studied by using Moessbauer spectroscopy and X-ray diffraction. The crystal is found to have a cubic spinel structure with the lattice constant a sub 0 =8.399 +- 0.005 A. It is noteworthy that a 20% replacement of Cu by Fe in the copper ferrite transforms the crystal structure from tetragonal to cubic and decreases the quadrupole shifts drastically. The iron ions at both A (tetrahedral) and B (octahedral) sites are found to be in ferric states. Atomic migration between A- and B-sites starts near 300 K and increases rapidly with increasing temperature to such a degree that 78% of the ferric ions at the A-sites move over to the B sites at 600 K.

  3. Observation of the strain-driven charge-ordered state in La sub 0 sub . sub 7 sub C a sub 0 sub . sub 3 MnO sub 3 sub - sub d elta thin film with oxygen deficiency

    CERN Document Server

    Prokhorov, V G; Kaminsky, G G; Svetchnikov, V L; Zandbergen, H W; Lee, Y P; Park, J S; Kim, K W

    2003-01-01

    The magnetic and transport properties of La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 sub - sub d elta films with an oxygen deficiency (delta approx 0.1) and a La sub 0 sub . sub 9 Ca sub 0 sub . sub 1 MnO sub 3 film with the stoichiometric oxygen content are investigated in a wide temperature range. It is shown that the charge-ordered insulating (COI) state is observed for a La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 2 sub . sub 9 film with thickness d <= 30 nm, which manifests mainly a cubic crystal structure with an anomalously small lattice parameter for this composition. An increase in the film thickness (d approx 60 nm) leads to a structural transition from the lattice-strained cubic to the relaxed rhombohedral phase, is accompanied by a shift of the Curie point (T sub C) to lower temperature and a frustration of the COI state. The magnetic and transport properties of the La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 2 sub . sub 9 film with d approx 60 nm are similar to those exhibi...

  4. Low-T magnetometry study of S = 1 Q2D [Ni(pyz)<sub>2sub>(H>2sub>O)>2sub>](BF>4sub>)>2sub> (pyz = pyrazine)

    Energy Technology Data Exchange (ETDEWEB)

    Manson, J. L. [Eastern Washington Univ., Cheney, WA (United States); Villa, D. Y. [Eastern Washington Univ., Cheney, WA (United States); Blackmore, W. J. A. [Univ. of Warwick, Coventry (United Kingdom); Brambleby, J. [Univ. of Warwick, Coventry (United Kingdom); Goddard, P. A. [Univ. of Warwick, Coventry (United Kingdom); Singleton, John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-13

    [Ni(pyz)<sub>2sub>(H>2sub>O)>2sub>](BF>4sub>)>2sub> (pyz = N<sub>2sub>C>4sub>H>4sub>) was synthesized by a solvent-free technique and its structure solved by synchrotron X-ray powder diffraction.1 The compound contains S = 1 Ni(II) ions and has tetragonal symmetry. Two-D [Ni(pyz)<sub>2sub>(H>2sub>O)>2sub>]2+ square lattices propagate in the ab-plane and stack along the c-axis (Fig. 1). Water ligands occupy axial sites and form H-bonds with interlayer BF<sub>4sub>- ions. SQUID magnetometry shows a possible transition to long-range magnetic order near 3 K. We measured the magnetization of [Ni(pyz)<sub>2sub>(H>2sub>O)>2sub>](BF>4sub>)>2sub> as a function of temperature to search for field-induced phase transitions and briefly report those findings here.

  5. Explaining R{sub D}{sup {sub (}{sub *}{sub )}} with leptoquarks and flavor symmetries

    Energy Technology Data Exchange (ETDEWEB)

    Schoenwald, Kay [TU Dortmund (Germany)

    2016-07-01

    Recently LHCb confirmed the anomalies in R{sub D}{sup {sub (}{sub *}{sub )}} previously measured by BaBar and Belle. We use flavor symmetries capable of explaining the observed mixing in the quark and lepton sector to constrain leptoquark couplings and study whether this models can explain the anomalies in R{sub D}{sup {sub (}{sub *}{sub )}}.

  6. Unusual Phase Diagram of CeOs<sub>4sub>Sb>12sub>

    Energy Technology Data Exchange (ETDEWEB)

    Ho, P. -C. [Fresno State Univ., Fresno, CA (United States); Goddard, P. A. [Warwick Univ., Coventry (United Kingdom); Maple, M. B. [Univ. of California, San Diego, CA (United States); Singleton, John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-01

    Filled skutterudite compounds, with the formula MT<sub>4sub>X>12sub>, where M is an alkali metal, alkaline-earth, lanthanide, or actinide, T is Fe, Ru, or Os, and X is P, As, or Sb, display a wide variety of interesting phenomena caused by strong electron correlations [1]. Among these, the three compounds CeOs<sub>4sub>Sb>12sub>, PrOs<sub>4sub>Sb>12sub>, and NdOs<sub>4sub>Sb>12sub>, formed by employing Periodic Table neighbors for M, span the range from an antiferromagnetic (AFM) semimetal (M = Ce) via a 1.85 K unconventional (quadrupolar-fluctuation mediated) superconductor (M = Pr) to a 1 K ferromagnet (FM; M = Nd). In the course of an extended study of these compounds, we uncovered an unusual phase diagram for CeOs<sub>4sub>Sb>12sub>.

  7. Microstructure study of the rare-earth intermetallic compounds R<sub>5sub>(SixGe>1-xsub>)>4sub> and R<sub>5sub>(SixGe>1-xsub>)>3sub>

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Qing [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    The unique combination of magnetic properties and structural transitions exhibited by many members of the R<sub>5sub>(SixGe>1-xsub>)>4sub> family (R = rare earths, 0 ≤ x ≤ 1) presents numerous opportunities for these materials in advanced energy transformation applications. Past research has proven that the crystal structure and magnetic ordering of the R<sub>5sub>(SixGe>1-xsub>)>4sub> compounds can be altered by temperature, magnetic field, pressure and the Si/Ge ratio. Results of this thesis study on the crystal structure of the Er<sub>5sub>Si>4sub> compound have for the first time shown that the application of mechanical forces (i.e. shear stress introduced during the mechanical grinding) can also result in a structural transition from Gd<sub>5sub>Si>4sub>-type orthorhombic to Gd<sub>5sub>Si>2sub>Ge>2sub>-type monoclinic. This structural transition is reversible, moving in the opposite direction when the material is subjected to low-temperature annealing at 500 °C.

  8. Thermoelectric power measurements in Fe doped La sub 0 sub . sub 6 sub 5 Ca sub 0 sub . sub 3 sub 5 MnO sub 3

    CERN Document Server

    Aslam, A; Zubair, M; Akhtar, M J; Nadeem, M

    2002-01-01

    We report measurements of the thermoelectric power (TEP) on the La sub 0 sub . sub 6 sub 5 Ca sub 0 sub . sub 3 sub 5 Mn sub 1 sub - sub x Fe sub x O sub 3 system for 0.00 <= x <= 0.07. The ferromagnetic and metallic transition temperatures are lowered and the TEP shows an increasingly positive trend with the addition of Fe. We also observe a clear magnetic contribution that manifests itself as a peak in the TEP close to the critical temperature. The activation energies determined from the TEP are seen to be insensitive to the Fe content. The data are interpreted firstly as showing a decrease in the density of active holes, i.e. holes that can participate in the hopping process, with increasing Fe content. Secondly the data suggest the role of magnetic scattering due to the clusters formed by the antiferromagnetically coupled Fe. Abrupt changes in the variation of the TEP are observed at the concentration region x approx 0.04 consistent with the hole density variation and with previously reported transp...

  9. Nearly constant magnetic entropy change involving two closely spaced transitions in the compound LaFe sub 1 sub 1 sub . sub 3 sub 7 sub 5 Al sub 1 sub . sub 6 sub 2 sub 5

    CERN Document Server

    Hu, F X; Wang, G J; Wang, J; Sun, J R; Zhang, X X; Cheng, Z H; Shen, B G

    2003-01-01

    A large change in the magnetic entropy, |DELTA S|, was observed in the Fe-based NaZn sub 1 sub 3 -type compound LaFe sub 1 sub 1 sub . sub 3 sub 7 sub 5 Al sub 1 sub . sub 6 sub 2 sub 5 , which was nearly temperature independent over a wide temperature range (an about 70 K span from approx 140 to 210 K). This behaviour of the magnetic entropy change is associated with two closely spaced magnetic transitions. X-ray diffraction investigation at different temperatures indicates that the crystal structure remains cubic, of NaZn sub 1 sub 3 type, when the magnetic state changes with temperature, but the cell parameter changes dramatically at the first-order transition point.

  10. Absorption cross sections for water, ammonia, methane, neopentane, the chloromethanes, and CF<sub>2sub>>2sub>Cl>2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Person, James C. [Argonne National Lab., IL (United States); Fowler, David E. [Macalester College, St. Paul, MN (United States); Nicole, Paul P. [Argonne National Lab., IL (United States)

    1975-12-01

    Experimental data on the absorption cross section (or differential oscillator strength) are presented for water, ammonia, methane, neopentane, CH<sub>3sub>Cl, CH<sub>2sub>Cl>2sub>, CHCl<sub>3sub>, CCl<sub>4sub>, and CF<sub>2sub>Cl>2sub>. In all cases the upper energy limit is 21.2 eV, and the lower energy limit is between 11 and 13 eV.

  11. Magnetic properties and inhomogeneous phase transition in (Fe sub x Co sub 0 sub . sub 5 sub - sub x)Pt sub 0 sub . sub 5 films

    CERN Document Server

    Jang, P W; Na, J G; Lee, S R

    1999-01-01

    (Fe sub x Co sub 0 sub . sub 5 sub - sub x)Pt sub 0 sub . sub 5 ternary thin films were deposited on glass substrates by using a dc sputtering method at room temperature and were subsequently annealed at 700 .deg. C in a high vacuum. A high degree of the (111) preferred orientation could be obtained in all the as-deposited films and was not destroyed, even though post annealing. The CoPt and the FePt binary alloys were completely mixed and had a L1 sub o -type ordered structure, as confirmed by single (222) peaks and by the linear variation of the lattice constant a sub o. The ordered structure of the FePt alloy was thought to have formed from the disordered structure by an inhomogeneous process, which was confirmed by the asymmetric peak shapes. The lattice parameter a sub o varied linearly with the Fe content while the coercivity showed a minimum value at the equiatomic composition of the Fe and the Co atoms.

  12. Crystallization of Zr<sub>2sub>PdxCu>1-xsub> and Zr<sub>2sub>NixCu>1-xsub> Metallic Glass

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Min [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    One interesting aspect of rretallic glasses is the numerous instances of the deviation of the phase selection from the amorphous state to thermodynamically stable phases during the crystallization process. Their devitrification pathways allow us to study the relationship between the original amorphous structure and their crystalline counter parts. Among the various factors of phase selections, size and electronic effects have been most extensively studied. Elucidating the phase selection process of a glassy alloy will be helpful to fill in the puzzle of the changes from disordered to ordered structures. In this thesis, Two model Zr<sub>2sub>PdxCu>1-xsub> and Zr<sub>2sub>NixCu>1-xsub> (x = 0, 0.25, 0.5, 0.75 and 1) glassy systems were investigated since: (1) All of the samples can be made into a homogenous metallic glass; (2) The atomic radii differ from Pd to Cu is by 11%, while Ni has nearly the identical atomic size compare to Cu. Moreover, Pd and Ni differ by only one valence electron from Cu. Thus, these systems are ideal to test the idea of the effects of electronic structure and size factors; (3) The small number of components in these pseudo binary systems readily lend themselves to theoretical modeling. Using high temperature X-ray diffraction (HTXRD) and thermal analysis, topological, size, electronic, bond and chemical distribution factors on crystallization selections in Zr<sub>2sub>PdxCu>1-xsub> and Zr<sub>2sub>NixCu>1-xsub> metallic glass have been explored. All Zr<sub>2sub>PdxCu>1-xsub> compositions share the same Cu11b phase with different pathways of meta-stable, icosahedral quasicrystalline phase (i-phase), and C16 phase formations. The quasicrystal phase formation is topologically related to the increasing icosahedral short range order (SRO) with Pd content in Zr<sub>2sub>PdxCu>1-xsub> system. Meta-stable C16 phase is competitive with

  13. Phase diagram and EXAFS study of La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 sub - sub x Ba sub x MnO sub 3 manganites

    CERN Document Server

    Ulyanov, A N; Yang, D S

    2003-01-01

    The phase diagram and local structure of La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 sub - sub x Ba sub x MnO sub 3 (x=0; 0.03; 0.06; ... 0.3) lanthanum manganites were studies. The Curie temperature, T sub c , of the compositions showed a sharp change near the concentrational structural orthorhombic-rhombohedral phase transition. Maximums of dispersion, sigma sub M sub n sub - sub O sup 2 , and asymmetry, sigma M sub n sub - sub O sup 3 , of pair distribution function for the Mn-O bond distances of MnO sub 6 octahedron on x-dependence were observed by extended X-ray absorption fine structure (EXAFS) analysis. The maximum of sigma sub M sub n sub - sub O sup 2 is caused by increase of dynamic rms displacements of Mn-O bond distances near the T sub c. The observed x dependence of sigma sub M sub n sub - sub O sup 3 reflects the reduction of charge carriers mobility at approaching to T sub c. (author)

  14. Sub Luna

    DEFF Research Database (Denmark)

    Rosenløv, Jesper

     Afhandlingen, Sub luna- kosmologier, religion og videnskab i antikken, undersøger de antikke forestillinger om naturens og universets indretning samt menneskets placering i verden således som dette kommer til udtryk i de kosmologiske teorier, der formuleredes i den antikke videnskabelige eller...... forestillinger indtog i de antikke kosmologier og i forlængelse heraf en klarlægning af forholdet mellem religion og det, der kunne kaldes antik naturlære eller naturfilosofi.  Undersøgelsen omfatter den græsk-romerske verden i perioden fra førsokratikerne til mellemplatonikerne). Kildematerialet begrænses til...

  15. Oxygen diffusion in Y sub 1 sub - sub x Pr sub x Ba sub 2 Cu sub 3 O sub 7 sub - subdelta observed by resistivity measurements

    CERN Document Server

    Diosa, J E; Mellander, B E

    1997-01-01

    In situ resistivity measurements have been used to monitor the oxygen uptake and removal for the ceramic system Y sub 1 sub - sub x Pr sub x Ba sub 2 Cu sub 3 O sub 7 sub - subdelta (YPBCO) in the temperature range 300 - 1000 K. The study of the out-diffusion of oxygen was performed by annealing the oxygenated samples in ambient air at constant heating rates. We found that, independently of x, the oxygen concentration O sub 7 sub - subdelta is preserved up to 600 K, and that oxygen diffuses out of the oxides at temperatures higher than 600 K. However, the rate of oxygen removal from PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta (PBCO) is greatly reduced as compared to the rate for pure YBa sub 2 Cu sub 3 O sub 7 sub - subdelta (YBCO), and decreases with increasing x in YPBCO. The study of the in-diffusion of oxygen was performed by annealing the deoxygenated samples in ambient air at constant heating rates. We found that, independently of x, the oxygen uptake takes place in the temperature range 550 - 750 K, whe...

  16. Magnetic properties and magnetic entropy change of LaFe sub 1 sub 1 sub . sub 5 Si sub 1 sub . sub 5 H sub y interstitial compounds

    CERN Document Server

    Chen Yuan Fu; Shen Bao Gen; Hu Feng Xia; Sun Ji Rong; Wang Guang Jun; Cheng Zhao Hua

    2003-01-01

    LaFe sub 1 sub 1 sub . sub 5 Si sub 1 sub . sub 5 H sub y interstitial compounds have been prepared by hydrogen absorption and subsequent desorption. The Curie temperatures are easily tunable for a wide temperature range from approx 195 to approx 340 K by hydrogen content. The maximal magnetic entropy changes, under a magnetic field change of 0-5 T, are as large as 16.8- 20.5 J kg sup - sup 1 K sup - sup 1 , exceeding that of Gd (|DELTA S| approx 9.8 J kg sup - sup 1 K sup - sup 1 at T sub C = 293 K) by 70-110% in the vicinity of room temperature. The large magnetic entropy change of all hydrides may be attributed to the first-order itinerant-electron metamagnetic transition confirmed by the Arrott plots. Large |DELTA S|, convenient adjustment of T sub C and small thermal and magnetic hystereses, make LaFe sub 1 sub 1 sub . sub 5 Si sub 1 sub . sub 5 H sub y interstitial hydrides promising candidates for magnetic refrigerants in the corresponding temperature range. (letter to the editor)

  17. Zinc diffusion in YBa sub 2 Cu sub 3 O sub 7 sub - sub x ceramics

    CERN Document Server

    Kulikov, G S; Skoryatina, E A; Usacheva, V P

    2002-01-01

    The zinc diffusion in YBa sub 2 Cu sub 3 O sub 7 sub - sub x ceramics with the porosity of 20-30% is studied with application of the sup 6 sup 5 Zn radioactive isotope. The diffusion coefficient temperature dependence is described by the D = 5 x 10 sup - sup 9 exp(-0.25 eV/kT) cm sup 2 s sup - sup 1 ratio. The conclusion is made on the primary zinc migration through the ceramics pores and intercrystalline layers

  18. Electronic phase separation in the rare-earth manganates (La sub 1 sub - sub x Ln sub x) sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 (Ln = Nd, Gd and Y)

    CERN Document Server

    Sudheendra, L

    2003-01-01

    Electron transport and magnetic properties of three series of manganates of the formula (La sub 1 sub - sub x Ln sub x) sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 with Ln = Nd, Gd and Y, wherein only the average A-site cation radius (r sub A ) and associated disorder vary, without affecting the Mn sup 4 sup + /Mn sup 3 sup + ratio, have been investigated in an effort to understand the nature of phase separation. All three series of manganates show saturation magnetization characteristic of ferromagnetism, with the ferromagnetic T sub c decreasing with increasing x up to a critical value of x, x sub c (x sub c = 0.6, 0.3, 0.2 respectively for Nd, Gd, Y). For x > x sub c , the magnetic moments are considerably smaller, showing a small increase around T sub M , the value of T sub M decreasing slightly with increase in x or decrease in (r sub A ). The ferromagnetic compositions (x x sub c are insulating. The magnetic and electrical resistivity behaviour of these manganates is consistent with the occurrence...

  19. NMR Studies of the Vanadium Spin Dynamics and Spin Structure in LiV<sub>2sub>O>4sub>, CaV<sub>2sub>O>4sub>, and (Li<sub>xV>1-xsub>)>3sub>BO>5sub> (x ≈ 0.33, 0.40)

    Energy Technology Data Exchange (ETDEWEB)

    Zong, Xiaopeng [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Strong electron correlation is believed to be an essential and unifying factor in diverse properties of condensed matter systems. Ground states that can arise due to electron correlation effects include Mott insulators, heavy fermion, ferromagnetism and antiferromagnetism, spin glasses, and high-temperature superconductivity. The electronic systems in transition metal oxide compounds are often highly correlated. In this thesis, the author presents experimental studies on three strongly correlated vanadium oxide compounds: LiV<sub>2sub>O>4sub>, (Li<sub>xV>1-xsub>)>3sub>BO>5sub>, and CaV<sub>2sub>O>4sub>, which have completely different ground states.

  20. Structural and Magnetothermal Properties of Compounds: Yb<sub>5sub>SixGe>4-xsub>,Sm>5sub>SixGe>4-xsub>, EuO, and Eu<sub>3sub>O>4sub>

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Kyunghan [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    The family of R<sub>5sub>SixGe>4-xsub> alloys demonstrates a variety of unique physical phenomena related to magneto-structural transitions associated with reversible breaking and reforming of specific bonds that can be controlled by numerous external parameters such as chemical composition, magnetic field, temperature, and pressure. Therefore, R<sub>5sub>SixGe>4-xsub> systems have been extensively studied to uncover the mechanism of the extraordinary magneto-responsive properties including the giant magnetoresistance (GMR) and colossal magnetostriction, as well as giant magnetocaloric effect (GMCE). Until now, more than a half of possible R<sub>5sub>SixGe>4-xsub> pseudobinary systems have been completely or partially investigated with respect to their crystallography and phase relationships (R = La, Pr, Nd, Gd, Tb, Dy, Er, Lu, Y). Still, there are other R<sub>5sub>SixGe>4-xsub> systems (R = Ce, Sm, Ho, Tm, and Yb) that are not studied yet. Here, we report on phase relationships and structural, magnetic, and thermodynamic properties in the Yb<sub>5sub>SixGe>4-xsub>and Sm<sub>5sub>SixGe>4-xsub> pseudobinary systems, which may exhibit mixed valence states. The crystallography, phase relationships, and physical properties of Yb<sub>5sub>SixGe>4-xsub> alloys with 0 ≤ x ≤ 4 have been examined by using single crystal and powder x-ray diffraction at room temperature, and dc magnetization and heat capacity measurements between 1.8 K and 400 K in magnetic fields ranging from 0 to 7 T. Unlike the majority of R<sub>5sub>SixGe>4-xsub> systems studied to date, where R is the rare earth metal, all Yb-based germanide-silicides with the 5:4 stoichiometry crystallize in the same Gd<sub>5sub>Si>4sub>-type structure. The magnetic properties of Yb<sub>5sub>SixGe>4-xsub> materials are nearly composition

  1. Tunable White-Light Emission in Single-Cation-Templated Three-Layered 2D Perovskites (CH <sub>3sub> CH <sub>2sub> NH <sub>3sub> ) <sub>4sub> Pb <sub>3sub> Br <sub>10–xsub> Cl <sub>x>

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Lingling; Wu, Yilei; Stoumpos, Constantinos C.; Traore, Boubacar [Institut; Katan, Claudine [Institut; Even, Jacky [Fonctions; Wasielewski, Michael R.; Kanatzidis, Mercouri G.

    2017-08-16

    Two-dimensional (2D) hybrid halide perovskites come as a family (B)<sub>2sub>(A)>n-1sub>PbnX>3n+1sub> (B and A= cations; X= halide). These perovskites are promising semiconductors for solar cells and optoelectronic applications. Among the fascinating properties of these materials is white-light emission, which has been mostly observed in single-layered 2D lead bromide or chloride systems (n = 1), where the broad emission comes from the transient photoexcited states generated by self-trapped excitons (STEs) from structural distortion. Here we report a multilayered 2D perovskite (n = 3) exhibiting a tunable white-light emission. Ethylammonium (EA+) can stabilize the 2D perovskite structure in EA<sub>4sub>Pb>3sub>Br>10–xsub>Clx> (x = 0, 2, 4, 6, 8, 9.5, and 10) with EA+ being both the A and B cations in this system. Because of the larger size of EA, these materials show a high distortion level in their inorganic structures, with EA4Pb3Cl10 having a much larger distortion than that of EA<sub>4sub>Pb>3sub>Br>10sub>, which results in broadband white-light emission of EA<sub>4sub>Pb>3sub>Cl>10sub> in contrast to narrow blue emission of EA4Pb3Br10. The average lifetime of the series decreases gradually from the Cl end to the Br end, indicating that the larger distortion also prolongs the lifetime (more STE states). The band gap of EA<sub>4sub>Pb>3sub>Br>10–xsub>Clx> ranges from 3.45 eV (x = 10) to 2.75 eV (x = 0), following Vegard’s law. First-principles density functional theory calculations (DFT) show that both EA<sub>4sub>Pb>3sub>Cl>10sub> and EA<sub>4sub>Pb>3sub>Br>10sub> are direct band gap semiconductors. The color rendering index (CRI) of the series improves from 66 (EA<sub>4sub>Pb>3sub>Cl>10sub>) to 83 (EA<sub>4sub>Pb>3sub>Br>0.5sub>Cl>9.5sub>), displaying high tunability and versatility of the

  2. Electromechanical properties of Co sub 0 sub . sub 6 Zn sub 0 sub . sub 4 Fe sub 2 O sub 4 ferrite transducer

    CERN Document Server

    Tawfik, A

    2001-01-01

    Co sub 0 sub . sub 6 Zn sub 0 sub . sub 4 Fe sub 2 O sub 4 ferrite has been prepared by the general ceramic method. The resonance frequency of the disk for the radial and thickness mode was investigated as a function of mechanical stress. The increase of the resonance frequency of the transducer is attributed to domain wall motion inhibition. The increase of ultrasonic velocity with increasing mechanical stress can be explained as due to retarding the oscillation of the ferrimagnetic domains under applied high-frequency electric field. The induced strain increases the resonance frequency. The high values of the electromechanical coupling factor for the radial mode K sub p , and thickness mode, K sub t , indicate that this composition is useful for producing high-frequency ultrasonic waves that can be used in modern technology.

  3. Processing and structure/property relations in Ba(Zn sub 1 sub / sub 3 Ta sub 2 sub / sub 3)O sub 3 microwave ceramics

    CERN Document Server

    Qazi, I

    2001-01-01

    Microwave filters utilize extensively, complex perovskite barium zinc tantalate ceramics, due to their superior selectivity and near zero temperature coefficient. A study of Ba sub 1 sub - sub x Sr sub x [Zn sub 1 sub / sub 3 (Ta sub 1 sub - sub y Nb sub y) sub 2 sub / sub 3]O sub 3 (BSZNT) synthesised by a mixed oxide route was conducted to understand the relationship between structure/microstructure and dielectric properties. Densities >95% and 97Vo were achieved in undoped (x=0 y=0) and Sr sup + sup 2 and or Nb sup + sup 5 doped Ba(Zn sub 1 sub / sub 3 Ta sub 2 sub / sub 3)O sub 3 (BZT) respectively. The investigation found a reversible order-disorder phase transition in pure barium zinc tantalate at approx 1600 degC. X-ray diffraction (XRD) showed a disordered cubic phase above, and an ordered trigonal-phase below, 1600 degC. Thermogravimetric analysis detected weight loss due to zinc oxide evaporation beginning at approximately 1200 degC. Thus, non-perovskite phases such BaTa sub 2 O sub 6 , observed as ...

  4. Magnetic properties and structure of the intermetallic compounds La sub 2 (Co sub 1 sub - sub x Fe sub x) sub 1 sub 6 Ti

    CERN Document Server

    Liu, Q L; Xu, J; Chen, X L; Huo, G Y; Liang, J K; Shen, B G

    1998-01-01

    The effect of substitution of Fe for Co in the compounds La sub 2 (Co sub 1 sub - sub x Fe sub x) sub 1 sub 6 Ti (x=0.0-0.5) on the crystal structure and magnetic properties has been investigated. The lattice parameters and the unit-cell volume of La sub 2 (Co sub 1 sub - sub x Fe sub x) sub 1 sub 6 Ti increase with x in the range 00.1. The easy-magnetization direction changes from the easy-axis direction (0<=x<=0.3) to the easy-plane direction (x=0.4), and the anisotropy field H sub A decreases with the Fe substitution. Evidence for spin reorientation in the compounds La sub 2 (Co sub 1 sub - sub x Fe sub x) sub 1 sub 6 Ti for 0.3<=x<=0.44 was observed in the M-T and chi sub a sub c -T curves. (author)

  5. Hydrodeoxygenation of p -Cresol over Pt/Al <sub>2sub> O <sub>3sub> Catalyst Promoted by ZrO <sub>2sub> , CeO <sub>2sub> , and CeO <sub>2sub> –ZrO <sub>2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Weiyan [Xiangtan Univ. (China). School of Chemical Engineering; Washington State Univ., Pullman, WA (United States). Voiland School of Chemical Engineering and Bioengineering; Wu, Kui [Xiangtan Univ. (China). School of Chemical Engineering; Liu, Pengli [Xiangtan Univ. (China). School of Chemical Engineering; Li, Lu [Xiangtan Univ. (China). School of Chemical Engineering; Yang, Yunquan [Xiangtan Univ. (China). School of Chemical Engineering; Wang, Yong [Washington State Univ., Pullman, WA (United States). Voiland School of Chemical Engineering and Bioengineering; Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-07-20

    ZrO<sub>2sub>-Al>2sub>O>3sub> and CeO<sub>2sub>-Al>2sub>O>3sub> were prepared by a co-precipitation method and selected as supports for Pt catalysts. The effects of CeO<sub>2sub> and ZrO<sub>2sub> on the surface area and Brønsted acidity of Pt/Al<sub>2sub>O>3sub> were studied. In the hydrodeoxygenation (HDO) of p-cresol, the addition of ZrO<sub>2sub> promoted the direct deoxygenation activity on Pt/ZrOO<sub>2sub>-Al>2sub>O>3sub> via Caromatic-O bond scission without benzene ring saturation. Pt/CeOO<sub>2sub>-Al>2sub>O>3sub> exhibited higher deoxygenation extent than Pt/Al<sub>2sub>O>3sub> due to the fact that Brønsted acid sites on the catalyst surface favored the adsorption of p-cresol. With the advantages of CeO<sub>2sub> and ZrO<sub>2sub> taken into consideration, CeO<sub>2sub>-ZrOO>2sub>-Al>2sub>O>3sub> was prepared, leading to the highest HDO activity of Pt/CeO<sub>2sub>-ZrOO>2sub>-Al>2sub>O>3sub>. The deoxygenation extent for Pt/CeO<sub>2sub>-ZrOO>2sub>-Al>2sub>O>3sub> was 48.4% and 14.5% higher than that for Pt/ZrO2O<sub>2sub>-Al>2sub>O>3sub> and Pt/CeOO<sub>2sub>-Al>2sub>O>3sub>, respectively.

  6. Novel Solution Process for Fabricating Ultra-Thin-Film Absorber Layers in Fe<sub>2sub>SiS>4sub> and Fe<sub>2sub>GeS>4sub> Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Orefuwa, Samuel A.; Lai, Cheng-Yu; Dobson, Kevin D.; Ni, Chaoying; Radu, Daniela R.

    2014-05-12

    Fe<sub>2sub>SiS>4sub> and Fe<sub>2sub>GeS>4sub> crystalline materials posses direct bandgaps of ~1.55 and ~1.4 eV respectively and an absorption coefficient larger than 10^5 cm–1; their theoretical potential as solar photovoltaic absorbers has been demonstrated. However, no solar devices that employ either Fe<sub>2sub>SiS>4sub> or Fe<sub>2sub>GeS>4sub> have been reported to date. In the presented work, nanoprecursors to Fe<sub>2sub>SiS>4sub> and Fe<sub>2sub>GeS>4sub> have been fabricated and employed to build ultra-thin-film layers via spray coating and rod coating methods. Temperature-dependent X-Ray diffraction analyses of nanoprecursors coatings show an unprecedented low temperature for forming crystalline Fe<sub>2sub>SiS>4sub> and Fe<sub>2sub>GeS>4sub>. Fabricating of ultra-thin-film photovoltaic devices utilizing Fe<sub>2sub>SiS>4sub> and Fe<sub>2sub>GeS>4sub> as solar absorber material is presented.

  7. Magnetotransport and charge transfer studies on delta-modulation-doped In sub x Ga sub 1 sub - sub x As/Al sub y Ga sub 1 sub - sub y As strained single quantum wells

    CERN Document Server

    Jung, M; Kim, T W; Yoo, K H; Kim, M D; Park, H S; Kim, D L

    1999-01-01

    Shubnikov-de Haas (S-dH) and Van der Pauw Hall-effect measurements on a In sub 0 sub . sub 1 sub 8 Ga sub 0 sub . sub 8 sub 2 As/Al sub 0 sub . sub 2 sub 5 Ga sub 0 sub . sub 7 sub 5 As strained single quantum well grown by molecular beam epitaxy have been performed to investigate the existence of the two-dimensional electron gas (2DEG) in the In sub 0 sub . sub 1 sub 8 Ga sub 0 sub . sub 8 sub 2 As single quantum well. The fast Fourier transform for the S-dH data and the observation of the quantum Hall effect clearly indicate 2DEG occupation of a subband in the In sub 0 sub . sub 1 sub 8 Ga sub 0 sub . sub 8 sub 2 As single quantum well. Electronic subband energy and the corresponding wavefunction in the In sub 0 sub . sub 1 sub 8 Ga sub 0 sub . sub 8 sub 2 As quantum well were calculated by a self-consistent method taking into account exchange-correlation effects together with strain and nonparabolicity effects.

  8. Copper(I) Complexes of N-thiophosphorylated Bis-thiourea [CH^sub 2^NHC(S)NHP(S)(OiPr)^sub 2^]^sub 2^ and Phosphines (PPh^sub 3^, Ph^sub 2^P(CH^sub 2^)^sub 1-3^PPh^sub 2^, Ph^sub 2^P(C^sub 5^H^sub 4^FeC^sub 5^H^sub 4^)PPh^sub 2^): Versatile Structures and Luminescence

    National Research Council Canada - National Science Library

    Damir A Safin; Maria G Babashkina; Axel Klein

    2010-01-01

    ...^{Ph^sub 2^P(CH^sub 2^)^sub 3^PPh^sub 2^}^sub 2^L] (4) or [Cu^sub 2^{Ph^sub 2^P(C^sub 5^H^sub 4^FeC^sub 5^H^sub 4^)PPh^sub 2^}^sub 2^L] (5) complexes. The structures of these compounds were investigated by IR...

  9. Electronic properties of new superconductors based on Ca(Al sub x Si sub 1 sub - sub x) sub 2 and Sr(Ga sub x Si sub 1 sub - sub x) sub 2 in crystal and nanotubular states

    CERN Document Server

    Shein, I R; Medvedeva, N I; Ivanovskij, A L

    2002-01-01

    The zone structures of the new Ca(Al sub x Si sub 1 sub - sub x) sub 2 and Sr(Ga sub x Si sub 1 sub - sub x) sub 2 layered superconductors (AlB sub 2 -type) are studied through the LMTO first-principle full-potential method. It is shown that the superconducting properties of the ternary silicides is conditioned by high density of the (Ca, Sr)d-states near the Fermi level, whereas the T sub C growth by the Sr(Ga sub x Si sub 1 sub - sub x) sub 2 -> Ca(Al sub x Si sub 1 sub - sub x) sub 2 transition is related to the increase in the photon frequencies due to the atoms mass decrease. Modeling the electron properties of the hypothetical (11, 11) and (20, 0) CaAlSi and SrGaSi nanotubes is accomplished. The silicide systems by transition from the crystalline to nanotubular state retain the metal-like properties. The template and film convolution methods may become the methods for obtaining the silicide nanotubes

  10. Electron spin resonance study of a La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 single crystal

    CERN Document Server

    Joh, K W; Lee, C E; Hur, N H; Ri, H C

    2003-01-01

    Comprehensive measurements of electron spin resonance were carried out on a La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 single crystal over a wide temperature range covering the ferromagnetic as well as the paramagnetic phases. Our analysis of the asymmetric lineshapes indicates that the phase segregation of good and poor conducting regions persists far above the ferromagnetic-paramagnetic phase transition temperature.

  11. Specific heat of YBa sub 2 Cu sub 4 O sub 8 near T sub c

    Energy Technology Data Exchange (ETDEWEB)

    Willis, J.O. (Los Alamos National Lab., NM (USA)); Tomeno, Izumi; Miyatake, Takayuki; Itoh, Takao; Tai, Keishi; Koshizuka, Naoki; Tanaka, Shoji (International Superconductivity Tech. Center, Tokyo (Japan). Superconductivity Research Lab.)

    1990-01-01

    Specific heat measurements are reported for a polycrystalline, bulk sample of YBa{sub 2}Cu{sub 4}O{sub 8} prepared at high oxygen pressure. The magnitude of the idealized specific heat jump {triangle}C{sub p}/T at {Tc} (= 80 {plus minus} 0.5K) is 15.5 {plus minus} 2 mJ/K{sup 2}-mole. The transition width {triangle} {Tc} is about 3K. The size of the jump is greatly reduced compared to YBa{sub 2}Cu{sub 3}O{sub 7}. The normal state magnetic susceptibility is somewhat smaller than in YBa{sub 2}Cu{sub 3}O{sub 7} and is temperature dependent. The results suggest a smaller electronic density of states for YBa{sub 2}Cu{sub 4}O{sub 8}. 13 refs., 2 figs., 2 tabs.

  12. Moessbauer study of mixed crystalline (Eu sub 2 O sub 3) sub x (Fe sub 2 O sub 3) sub 1 sub - sub x (x=0.45)

    CERN Document Server

    Kim, J G; Kim, Y H; Kim, E C

    1998-01-01

    The crystallography and the temperature dependence of the Moessbauer parameters of mixed crystalline (Eu sub 2 O sub 3) sub x (Fe sub 2 O sub 3) sub 1 sub - sub x (x=0.45) were studied by the method of X-ray diffraction at room temperature and Moessbauer spectroscopy within the temperature range from liquid nitrogen temperature to 540 K. The X-ray diffraction pattern of the sample showed the coexistence of cubic and orthorhombic crystal phases. The Moessbauer spectrum of 540 K indicated a crystal phase which was in good agreement with the X-ray result and gave no indication, within the experimental error, of any other crystal phases. By analyzing the temperature dependence of the Moessbauer parameters by using the spin-wave theory and the Debye model, useful result were obtained for examining the changes in the physical properties in mixed crystalline system.

  13. Crystallization and Moessbauer studies of the Fe sub 7 sub 8 Al sub 4 Nb sub 5 B sub 1 sub 2 Cu sub 1 alloy

    CERN Document Server

    Kim, C S; Kim, S B; Park, J Y; Kim, K Y; Noh, T H; Oak, H N

    1998-01-01

    A melt-spun Fe sub 7 sub 8 Al sub 4 Nb sub 5 B sub 1 sub 2 Cu sub 1 alloy with an ultra-thin ribbon has been studied by x-ray diffraction, Moessbauer spectroscopy, and vibrating sample magnetometry. The average hyperfine field H sub h sub f (T) of the amorphous state shows temperature dependence of [H sub h sub f (T) - H sub h sub f (0)]/H sub h sub f (0) -0.53(T/T sub c) sup 3 sup / sup 2 - 0.21(T/T sub c < 0.7, indicative of spin-wave excitation. The quadrupole splitting just above the Curie temperature Tc is 0.42 mm/s, whereas the quadrupole shift below T sub c is zero. The Curie and the crystallization temperature are T sub c = 450 K and T sub x = 703 K, respectively, for a heating rate of 5 K/min. The occupied area ratio of the alpha-Fe phase flash-annealed at 723 K is 59% and remains unchanged. The crystallization temperature of the flash-annealed alloy becomes lower, and the formation of an alpha-Fe is easier than that of the conventional alloy. The flash-annealing technique is effective in improvin...

  14. The seeding effect of floating zone growth on Nd sub 1 sub . sub 8 sub 5 Ce sub 0 sub . sub 1 sub 5 CuO sub 4 and Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 sub - subdelta single crystals

    CERN Document Server

    Lin, C T; Liang, B

    2002-01-01

    Single crystals with the [100] orientation were selected and used as seeds to investigate the effect of travelling solvent floating zone growth on superconducting oxides of Nd sub 1 sub . sub 8 sub 5 Ce sub 0 sub . sub 1 sub 5 CuO sub 4 and Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 sub - subdelta. The number of nuclei was remarkably reduced and random nuclei could be eased when the seeding was applied during the growth of Nd sub 1 sub . sub 8 sub 5 Ce sub 0 sub . sub 1 sub 5 CuO sub 4 single crystals, compared to the crystals grown without seed. The crystal could preferentially grow on the seed although some additional nuclei occurred at the solid-liquid interface during the initial growth process. In consequence, the crystal ingot obtained is a large single grain having dimensions of 5 mm in diameter and 40 mm in length. The orientation of the seeded growth crystal was found to be 5deg off the [100] seed identified by an x-ray Laue pattern. For the growth of Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 sub - subdelta, it...

  15. Characterization of Si sub 1 sub - sub x Ge sub x thin films prepared by sputtering

    CERN Document Server

    Noguchi, T

    2000-01-01

    By bombarding solid targets, we deposited Si sub 1 sub - sub x Ge sub x thin films by sputtering without using inflammable CVD (chemical vapor deposition) gases. After the B sup + -implanted Si sub 1 sub - sub x Ge sub x films were thermally annealed, they were characterized. As the content of Ge increased, the refractive index increased and the band edge narrowed. The higher the annealing temperature, the lower the resistivity. For Si sub 1 sub - sub x Ge sub x films with a high Ge content (X approx 0.5), the flat-band voltage of the gate deduced from C-V curve was adjusted to the middle point between p sup + and n sup + polySi gates. Boron-doped SiGe films are promising gate materials for MOS (metal oxide semiconductor) and SOI (silicon on insulator) transistors driven at low driving voltage.

  16. Quasi-homoepitaxial growth of a-axis oriented PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta thick film on (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystal

    CERN Document Server

    Sato, M; Morishita, T

    2003-01-01

    The structural characterizations of the quasi-homoepitaxial growth of a-axis oriented PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta thick film grown on (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystal were investigated in comparison with those of the film grown on (001) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystal. The a-axis oriented PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta films, expected to be a barrier layer, were prepared using a dc-95 MHz hybrid plasma sputtering on (100) and (001) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystals that are superconducting ground planes. The atomic force microscopy image revealed that the surfaces of 700-nm-thick a-axis PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta films on (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single crystals were smooth with a mean roughness of 2.8 nm. X-ray diffraction scans showed that a-axis PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta films deposited on (100) YBa sub 2 Cu sub 3 O sub 7 sub - subdelta single cry...

  17. Exploration of R<sub>2sub>XM>2sub> (R=Sc, Y, Ti, Zr, Hf, rare earth; X=main group element; M=transition metal, Si, Ge): Structural Motifs, the novel Compound Gd<sub>2sub>AlGe>2sub> and Analysis of the U<sub>3sub>Si>2sub> and Zr<sub>3sub>Al>2 sub>Structure Types

    Energy Technology Data Exchange (ETDEWEB)

    McWhorter, Sean William [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    In the process of exploring and understanding the influence of crystal structure on the system of compounds with the composition Gd<sub>5sub>(SixGe>1-xsub>)>4sub> several new compounds were synthesized with different crystal structures, but similar structural features. In Gd<sub>5sub>(SixGe>1-xsub>)>4sub>, the main feature of interest is the magnetocaloric effect (MCE), which allows the material to be useful in magnetic refrigeration applications. The MCE is based on the magnetic interactions of the Gd atoms in the crystal structure, which varies with x (the amount of Si in the compound). The crystal structure of Gd<sub>5sub>(SixGe>1-xsub>)>4sub> can be thought of as being formed from two 32434 nets of Gd atoms, with additional Gd atoms in the cubic voids and Si/Ge atoms in the trigonal prismatic voids. Attempts were made to substitute nonmagnetic atoms for magnetic Gd using In, Mg and Al. Gd<sub>2sub>MgGe>2sub> and Gd<sub>2sub>InGe>2sub> both possess the same 32434 nets of Gd atoms as Gd<sub>5sub>(SixGe>1-xsub>)>4sub>, but these nets are connected differently, forming the Mo<sub>2sub>FeB>2sub> crystal structure. A search of the literature revealed that compounds with the composition R<sub>2sub>XM>2sub> (R=Sc, Y, Ti, Zr, Hf, rare earth; X=main group element; M=transition metal, Si, Ge) crystallize in one of four crystal structures: the Mo<sub>2sub>FeB>2sub>, Zr<sub>3sub>Al>2sub>, Mn<sub>2sub>AlB>2sub> and W<sub>2sub>CoB>2sub> crystal structures. These crystal structures are described, and the relationships between them are highlighted. Gd<sub>2sub>AlGe>2sub> forms an entirely new crystal structure, and the details of its synthesis and characterization are given. Electronic structure calculations are performed to understand the nature of bonding in this compound and how

  18. Critical Behavior of Thermal Expansion and Magnetostriction in the Vicinity of the First order transition at the Curie Point of Gd<sub>5sub>(SixGe>1-xsub>)>4sub>

    Energy Technology Data Exchange (ETDEWEB)

    Han, Mangui [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Thermal expansion (TE) and magnetostriction (MS) measurements have been conducted for Gd<sub>5sub>(SixGe>1-xsub>)>4sub> with a series of x values to study its critical behavior in the vicinity of transition temperatures. It was found that the Curie temperature of Gd<sub>5sub>(SixGe>1-xsub>)>4sub> for x 0 ~ 0.5 is dependent on magnetic field, direction of change of temperature (Tc on cooling was lower than Tc on heating), purity of Gd starting material, compositions, material preparation methods, and also can be triggered by the external magnetic field with a different dT/dB rate for different x values. For Gd<sub>5sub>(Si>1.95sub>Ge>2.05sub>), Gd<sub>5sub>(Si>2sub>Ge>2sub>), Gd<sub>5sub>(Si>2.09sub>Ge>1.91sub>), it was also found that the transition is a first order magneto-structural transition, which means the magnetic transition and crystalline structure transition occur simultaneously, and completely reversible. Temperature hysteresis and phase coexistence have been found to confirm that it is a first order transformation. While for Gd<sub>5sub>(Si>0.15sub>Ge>3.85sub>), it is partially reversible at some temperature range between the antiferromagnetic and the ferromagnetic state. For Gd<sub>5sub>(Si>2.3sub>Ge>1.7sub>) and Gd<sub>5sub>(Si>3sub>Ge>1sub>), it was a second order transformation between the paramagnetic and ferromagnetic state, because no ΔT have been found. Giant magnetostriction was only found on Gd<sub>5sub>(Si>1.95sub>Ge>2.05sub>), Gd<sub>5sub>(Si>2sub>Ge>2sub>), Gd<sub>5sub>(Si>2.09sub>Ge>1.91sub>) in their vicinity of first order transformation. MFM images have also been taken on polycrystal sample Gd<sub>5sub>(Si>2.09sub>Ge>1.91sub>) to investigate the transformation process. The results also indicates that the Curie temperature was lower and the thermally

  19. Structural modifications and phonon softening in Bi sub 2 Sr sub 2 Ca sub 1 sub - sub x R sub x Cu sub 2 O sub 8 sub + subdelta (R = Pr and Gd) single crystals

    CERN Document Server

    Feng, S J; Han, Q; Ma, J; Shi, L; Sun, X F; Zuo, J; Li, X G

    2003-01-01

    The phonon Raman spectra of Bi sub 2 Sr sub 2 Ca sub 1 sub - sub x R sub x Cu sub 2 O sub 8 sub + subdelta (R = Pr and Gd) single crystals are systematically investigated. The experimental results show that the O(2) sub S sub r A sub 1 sub g mode softens with Pr and Gd doping, while the O(1) sub C sub u B sub 1 sub g mode softens with Pr doping but hardens with Gd doping. The changes of average ionic radius on the Ca site in Bi-based cuprates can account well for the Raman frequency shifts of the O(1) sub C sub u mode, but have little influence on the O(2) sub S sub r mode. The frequency softening of the O(2) sub S sub r mode in Pr-and Gd-doped Bi2212 crystals mainly results from contraction of the BiO bilayers with doping content. The correlation between the O(2) sub S sub r mode frequency and the c-axis parameter as well as the incommensurate modulation wavelength is discussed.

  20. Specific heat of Ho sub 2 Co sub 17 and Er sub 2 Co sub 17

    Energy Technology Data Exchange (ETDEWEB)

    Franse, J.J.M.; Klaasse, J.C.P.; Sinnema, S. (Amsterdam Univ. (NL). Natuurkunding Lab.); Radwanski, R.J. (University of Mining and Metallurgy, Krakow (PL). Solid State Physics Dept.)

    1988-12-01

    The specific heat of polycrystalline samples of Ho{sub 2}Co{sub 17} and Er{sub 2}Co{sub 17} has been measured between 1.25 K and 38 K in zero field and in an applied field of 5 T. The electronic, lattice, nuclear and crystal field contributions to the specific heat have been separated.

  1. Phase composition and superconducting properties of (Pb sub 0 sub . sub 6 Sn sub y Cu sub 0 sub . sub 4 sub - sub y)Sr sub 2 (Y sub 1 sub - sub x Ca sub x)Cu sub 2 O sub z

    CERN Document Server

    Balchev, N; Kunev, B; Souleva, A; Tsacheva, T

    2001-01-01

    The effect of Sn-doping in (Pb sub 0 sub . sub 6 Sn sub y Cu sub 0 sub . sub 4 sub - sub y)Sr sub 2 (Y sub 1 sub - sub x Ca sub x)Cu sub 2 O sub z for 0 <= y <= 0.3 and 0 <= x <= 0.7 was investigated. It was established that a nearly pure 1212 phase could be obtained at 0 <= y <= 0.1 and 0 <= x <= 0.3. The obtained X-ray diffraction (XRD) patterns as well as the results of the inductively coupled plasma atomic emission spectrometry (ICP-AES) and energy-dispersive X-ray (EDX) analysis showed that the Sn-substitution was possible in the (Pb,Cu)-1212 phase. Superconductivity was observed at 0.4 <= x <= 0.7. The onset of the diamagnetic transitions varied from 10 to 30 K. The influence of the strong Pb deficiency on the superconducting properties of the samples was discussed. (authors)

  2. Effect of pelletization pressure on structural properties and critical current hysteresis of ceramic superconducting Bi sub 1 sub . sub 7 Pb sub 0 sub . sub 3 Sr sub 2 Ca sub 2 Cu sub 3 O sub y

    CERN Document Server

    Tepe, M; Abukay, D

    2003-01-01

    The effect of pelletization pressures on structural properties and critical current hysteresis of Bi sub 1 sub . sub 7 Pb sub 0 sub . sub 3 Sr sub 2 Ca sub 2 Cu sub 3 O sub y samples was investigated. The samples used in this study were prepared by classical solid-state reaction at the pressures from 100 up to 500 MPa. The obtained samples were characterized by resistance vs. temperature, (R-T), critical current density vs. applied magnetic field, (J sub c -H), material density vs. pressure, (rho-P), XRD, SEM, and EDAX. The results of this study showed that the quality of electrical and structural properties of Bi-2223 bulk superconductors strongly depends on the pelletization pressure. Pressing of bulk samples at 400 MPa produces textured grain alignment and associates microstructural modifications in order to enhance flux pinning and thus increases current carrying capacities. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  3. Hydrogen absorption-desorption properties of UZr sub 0 sub . sub 2 sub 9 alloy

    CERN Document Server

    Shuai Mao Bing; WangZhenHong; Zhang Yi Tao

    2001-01-01

    Hydrogen absorption-desorption properties of UZr sub 0 sub . sub 2 sub 9 alloy are investigated in detail at hydrogen pressures up to 0.4 MPa and over the temperature range of 300 to 723 K. It absorbs hydrogen up to 2.3 H atoms per F.U. (formula unit) by only one-step reaction and hence each desorption isotherm has a single plateau over nearly the whole hydrogen composition range. The enthalpy and entropy changes of the dissociation reaction are of -78.9 kJ centre dot mol sup - sup 1 H sub 2 and 205.3 J centre dot(K centre dot mol H sub 2) sup - sup 1 , respectively. The alloy shows high durability against powdering upon hydrogenation and may have good heat conductivity. It is predicted that UZr sub 0 sub . sub 2 sub 9 alloy may be a suitable material for tritium treatment and storage

  4. Conductivity and optical spectra of Pr sub 1 sub - sub x Y sub x Ba sub 2 Cu sub 3 O sub y (x=0, 0.5 and 1.0)

    CERN Document Server

    Kakinuma, K; Fueki, K

    1999-01-01

    In order to clarify the electronic structure of High-T sub c superconducting oxide, we measured the oxygen-nonstoichiometry, conductivity at temperatures, up to 12000 K, and the optical spectra for three kinds of oxides, YBa sub 2 Cu sub 3 O sub y , (Pr sub 0 sub . sub 5 Y sub 0 sub . sub 5)Ba sub 2 Cu sub 3 O sub y , and PrBa sub 2 Cu sub 3 O sub y. No difference was found in oxygen nonstoichiometry. At high temperature, we detected a conductivity minimum (sigma sub m sub i sub n) in the Log sub 1 sub 0 sigma-log sub 1 sub 0 Po sub 2 plot at constant temperature. From the slope of the Arrhenius plot for sigma sub m sub i sub n , the CT gap was 1.37, 1.32 and 1.21 eV for YBa sub 2 Cu sub 3 O sub y , (Pr sub 0 sub . sub 5 Y sub 0 sub . sub 5)Ba sub 2 Cu sub 3 O sub y , and PrBa sub 2 Cu sub 3 O sub y respectively. The energy gap (DELTA E) between the acceptor level and the top of the valence band was calculated from the slope of the Arrhenius plot for p-type conductivity. The DELTA E for the superconducting YB...

  5. Improvement of ferroelectric properties by heat treating SrBi sub 2 (Ta sub 1 sub - sub x Nb sub x) sub 2 O sub 9 /Bi sub 2 O sub 3 /SrBi sub 2 (Ta sub 1 sub - sub x Nb sub x) sub 2 O sub 9 heterostructure

    CERN Document Server

    Park, Y B; Jung, H J; Park, J W

    1998-01-01

    Ferroelectric properties of SrBi sub 2 TaNnO sub 9 (SBTN) thin films were changed in terms of the amount of Bi content in SBTN. We suggested that the addition of excess Bi in the films could be accomplished by heat treating SBTN/Bi sub 2 O sub 3 /SBTN heterostructure fabricated by r.f. magnetron sputtering method. excess Bi composition was controlled by changing the thickness of the sandwiched Bi sub 2 O sub 3 in SBTN/Bi sub 2 O sub 3 /SBTN heterostructure from 50 A to 400 A. As the thickness of Bi sub 2 O sub 3 films were increased from 0 to 100 A, the grain grew faster and the ferroelectric properties were improved. On the other hand, when the thickness of Bi sub 2 O sub 3 films was greater than 400 A, a Bi sub 2 Pt phase appeared as a second phase, which led to poor ferroelectric properties. The maximum remanent polarization (2Pr) and good coercive field (Ec) were obtained for the SBTN/Bi sub 2 O sub 3 (100A)/SBTN films. In this case, 2Pr and Ec were 14.75 mu C/cm sup 2 and 53.4kV/cm, respectively.

  6. Preparation of Si sub 1 sub - sub x sub - sub y Ge sub x C sub y semiconductor films on Si by ion implantation and solid phase epitaxy

    CERN Document Server

    Liu Xue Qin; Zhen Cong Mian; Zhang Jing; Yang Yi; Guo Yong

    2002-01-01

    Si sub 1 sub - sub x sub - sub y Ge sub x C sub y ternary alloy semiconductor films were prepared on Si(100) substrates by C ion implanting SiGe films and subsequent solid phase epitaxy (SPE). Two-step annealing technique was employed in the SPE processing. The properties of the alloy films were determined using Rutherford backscattering spectroscopy (RBS), Fourier transform infrared spectroscopy (FTIR) and High-resolution x-ray diffraction (HRXRD) measurements. It is shown that C atoms are located at substitutional sites and the incorporation of C relieves the compressive strain in the SiGe layer

  7. Pressure effect on the superconductivity and the metal-insulator transition in Cu sub 1 sub sub - sub x Zn sub x Ir sub 2 S sub 4

    CERN Document Server

    Cao, G; Kitazawa, H; Isobe, M; Matsumoto, T

    2002-01-01

    The variations of the superconducting transition temperature T sub c and the metal-insulator (MI) transition temperature T sub M sub I were investigated as a function of pressure in the superconducting Cu sub 1 sub sub - sub x Zn sub x Ir sub 2 S sub 4 (0.3 <= x <= 0.5) system. The experiment was performed by measuring the temperature dependence of resistance under the pressures up to 1.5 GPa. It is shown that the external pressure destroys the superconductivity, and gives rise to the MI transitions. The result is discussed in terms of the stabilization of the insulating phase at high pressures and the phase separation associated with the charge segregation. It is proposed that the BCS Cooper pairs compete with the proposed bipolarons under certain pressures.

  8. Anomalous strain relief and physical properties of La sub 0 sub . sub 5 Ca sub 0 sub . sub 5 MnO sub 3 films

    CERN Document Server

    Choi, C; Kim, D H; Lim, K D; Noh, T W; Jung, C U; Oh, S J; Lee, K B

    2000-01-01

    La sub 0 sub . sub 5 Ca sub 0 sub . sub 5 MnO sub 3 films were grown using pulsed laser deposition. Several factors, such as variation of substrates, interface effects, and annealing effects, influencing the properties of the grown films were investigated. As-grown films on LaAlO sub 3 substrates showed anomalous strain relief; they had strained and partly relaxed layers, both of which had tetragonal structures. On SrTiO sub 3 substrates, only coherently strained layers were observed. Such a difference of growth behaviors cannot be explained solely in terms of lattice mismatch since only partly relaxed layers appeared on LaAlO sub 3 and relaxed layers were obtained after annealing. The transport and the magnetic properties of the annealed films were quite different from those of the as-grown films.

  9. Cubic-tetragonal phase transition in Ca sub 0 sub . sub 0 sub 4 Sr sub 0 sub . sub 9 sub 6 TiO sub 3 a combined specific heat and neutron diffraction study

    CERN Document Server

    Gallardo, M C; Romero, F J; Cerro, J D; Seifert, F; Redfern, S A T

    2003-01-01

    The specific heat corresponding to the tetragonal-to-cubic transition in Ca sub 0 sub . sub 0 sub 4 Sr sub 0 sub . sub 9 sub 6 TiO sub 3 perovskite has been measured by conduction calorimetry. The order parameter of the transition has been obtained by means of neutron diffraction at low temperatures. Comparison of calorimetric data with the evolution of the order parameter indicates that this transition seems to follow a mean field Landau potential as in SrTiO sub 3. The linear behaviour of the excess of entropy versus temperature suggests that a 2-4 Landau potential is sufficient to describe the transition.

  10. Proton glass behaviour in a solid solution of gamma-irradiated deuterated betaine phosphate sub 0 sub . sub 1 sub 5 betaine phosphite sub 0 sub . sub 8 sub 5

    CERN Document Server

    Banys, J; Klimm, C; Voelkel, G; Kloepperpieper, A

    1997-01-01

    Measurements of the dielectric permittivity are reported for a deuterated solid solution of gamma-irradiated antiferroelectric (betainephosphate) sub 0 sub . sub 1 sub 5 ferroelectric (betainephosphite) sub 0 sub . sub 8 sub 5 at frequencies 20 H sub Z sub z. The freezing phenomena in DPB sub 0 sub . sub 1 sub 5 DBPI sub 0 sub . sub 8 sub 5 revealed the characteristics of a transition into a dipolar glass state. The activation energy was found to be E sub b = 311.6 K (0.027 eV). The Kutnjak model showed a non-typical glass behaviour with an estimated glass temperature of 55.4 K. (author). Letter-to-the-editor

  11. Thick film processing of YBa sub 2 Cu sub 3 O sub 7 sub - sub x

    CERN Document Server

    Wells, J J

    2000-01-01

    texture in the substrates used. A J sub c of approx 10 sup 4 Acm sup - sup 2 77K, 0T, was obtained with a precursor solution of 0.00375 mol/dm sup 3. The current carrying length scale was measured to be approx 1 mm showing there is good connectivity between the 1-2 mu m diameter grains. A route for producing textured silver substrates, and two techniques for producing YBCO thick films have been studied with a view to demonstrating an economical route for the fabrication of long lengths of YBCO tape. Silver ingots cold rolled to a deformation of 98 % and recrystallised at 800 deg C for 24 hours gave a left brace 110 right brace texture with a FWHM in phi of approx 20deg. These were used as substrates for the epitaxial growth of YBCO by both a low pO sub 2 melt processing technique and an ultrasonic spray pyrolysis technique. The low pO sub 2 melt processing technique enabled the melting point of YBCO to be lowered to 945 degC at a pO sub 2 of 5x10 sup - sup 3 atm such that the YBCO could be resolidified from t...

  12. Li/Ag<sub>2sub>VO>2sub>PO>4sub> batteries: the roles of composite electrode constituents on electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Bock, David C.; Bruck, Andrea M.; Pelliccione, Christopher J.; Zhang, Yiman; Takeuchi, Kenneth J.; Marschilok, Amy C.; Takeuchi, Esther S. (BNL); (SBU)

    2016-11-01

    Silver vanadium phosphorous oxide, Ag<sub>2sub>V>2sub>OPO>4sub>, was used as a model system to systematically study the impact on the constituents of a composite electrode, including polymeric and conductive additives, on electrochemistry. Three different electrode compositions were investigated.

  13. Magnetic properties of icosahedral MRu sub 1 sub 2 clusters

    CERN Document Server

    Deng Kai Ming; Xiao Chuan Yun; Wang Ke Lin

    1997-01-01

    The magnetic properties of icosahedral MRu sub 1 sub 2 clusters are studied using the discrete-variational local-spin-density-functional method, where M = V, Cr, Mn, Fe, Co, and Ni. The results show that all of the I sub h MRu sub 1 sub 2 clusters, just like the case for the I sub h Ru sub 1 sub 3 cluster, have double magnetic solutions. In contrast to the moment of 4 mu sub B for the I sub h Ru sub 1 sub 3 cluster, the total magnetic moments of the I sub h MRu sub 1 sub 2 clusters, ranging from 1 mu sub B to 20 mu sub B , have been changed greatly by the substitution of the central Ru atom with M. Among them, the NiRu sub 1 sub 2 cluster has a giant moment of 20 mu sub B. Furthermore, the NiRu sub 1 sub 2 cluster has nondegenerate ground state and could be expected to be remarkably stable. Therefore, for the purpose of enhancing the magnetic moment of the I sub h Ru sub 1 sub 3 cluster, Ni is a promising candidate as a dopant. Finally, we predict that all the I sub h MRu sub 1 sub 2 clusters except NiRu sub ...

  14. Hopping transport in an insulating quasicrystal bar of Al sub 7 sub 0 Pd sub 2 sub 2 sub . sub 5 Re sub 7 sub . sub 5 near the metal-insulator transition

    CERN Document Server

    Rosenbaum, R; Su, T I

    2003-01-01

    We have observed that the conductivity sigma(T) for the Al sub 7 sub 0 Pd sub 2 sub 2 sub . sub 5 Re sub 7 sub . sub 5 quasicrystal, with a resistivity ratio r = R(4.2 K)/R(300 K) = 13.2, obeys the variable-range hopping law, sigma(T) sigma sub 0 /exp [(T sub 0 /T)] supmu, in the temperature range between 64 mK and 1.6 K. The hopping exponent mu is extracted to be 0.23, close to the Mott exponent of 1/4, and T sub 0 is 3.5 K. This insulating behaviour is consistent with the prediction of a previously determined scaling law that bulk Al sub 7 sub 0 Pd sub 2 sub 2 sub . sub 5 Re sub 7 sub . sub 5 samples having r >= 12.8 will be insulating. Large positive magnetoresistances (MRs) were observed in this sample. The percentage change in the MR = DELTA R(B, T)/R(0, T), as high as 185% at T 0.11 K and B = 17 T, is the largest value ever reported in Al-Pd-Re QCs, to our knowledge. The difficulties using existing MR theories to explain the MR data for this insulating sample near the metal-insulator transition are disc...

  15. Anisotropy of superconducting transformation in magnetic fields in Nd sub 1 sub . sub 8 sub 5 Ce sub 0 sub . sub 1 sub 5 CuO sub 4 monocrystal

    CERN Document Server

    Panova, G K; Chernoplekov, N A; Emelchenko, G A; Malyuk, A N; Lin, S T

    2002-01-01

    The anisotropy of the superconducting properties of the Nd sub 1 sub . sub 8 sub 5 Ce sub 0 sub . sub 1 sub 5 CuO sub 4 monocrystal is studied by resistance within the temperature range of 2-30 K in the 0, 1, 2, 4, 6 Tl magnetic fields in the a-b plane. The T sub c (H) and H sub c sub 2 (T) strong anisotropy was observed by the magnetic field different orientation in the a-b plane. The zero direction in the gap of the order parameter is determined. The analysis of the experimental data shows, that such a result may be related to the change in the symmetry in the copper atoms surrounding, leading to its reduction from the tetragonal to orthorhombic one in the low-temperature area. The comparison with the La sub 1 sub . sub 8 sub 5 Sr sub 0 sub . sub 1 sub 5 CuO sub 4 gives all grounds to suppose, that the superconductivity mechanism in the electron- and hole-doped superconductor is similar and the observed difference is connected with the structure peculiarities

  16. Properties of the (Sm sub 0 sub . sub 3 sub 3 Eu sub 0 sub . sub 3 sub 3 Gd sub 0 sub . sub 3 sub 3)Ba sub 2 Cu sub 3 O sub y superconductor prepared by different processes in air

    CERN Document Server

    Giovannelli, F; Monot-Laffez, I

    2003-01-01

    Bars and pellets of the (Sm sub 0 sub . sub 3 sub 3 Eu sub 0 sub . sub 3 sub 3 Gd sub 0 sub . sub 3 sub 3)Ba sub 2 Cu sub 3 O sub x superconductor were processed in air, using the floating zone method and the top-seeded melt-textured growth method, respectively. The samples were prepared using different experimental conditions, i.e. maximal processing temperature, translation rate or cooling rate. Their physical properties and their microstructure were studied. All the samples exhibit a satisfying superconducting transition whereas the critical current density greatly depends on the processing parameters. The sample prepared by the floating zone method at 1070 deg C with a translation rate of 2 mm h sup - sup 1 exhibits a very high J sub c value of 70000 A cm sup - sup 2 in the self-field and more than 30000 A cm sup - sup 2 at 1.7 T. The pellet processed at 1080 deg C with a cooling rate of 2 deg C h sup - sup 1 has a high J sub c reaching about 56000 A cm sup - sup 2 in the self-field and more than 32000 A ...

  17. Mechanism of CO <sub>2sub> Hydrogenation on Pd/Al <sub>2sub> O <sub>3sub> Catalysts: Kinetics and Transient DRIFTS-MS Studies

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiang; Shi, Hui; Kwak, Ja Hun; Szanyi, János

    2015-09-17

    The hydrogenation of CO<sub>2sub> was investigated over a wide range of reaction conditions, using two Pd/γ-Al<sub>2sub>O>3sub> catalysts with different Pd loadings (5% and 0.5%) and dispersions (~11% and ~100%, respectively). Turnover rates for CO and CH<sub>4sub> formation were both higher over 5% Pd/Al<sub>2sub>O>3sub> with a larger average Pd particle size than those over 0.5% Pd/Al<sub>2sub>O>3sub> with a smaller average particle size. The selectivity to methane (22-40%) on 5% Pd/Al<sub>2sub>O>3sub> was higher by a factor of 2-3 than that on 0.5% Pd/Al<sub>2sub>O>3sub>. The drastically different rate expressions and apparent energies of activation for CO and CH<sub>4sub> formation lead us to conclude that reverse water gas shift and CO<sub>2sub> methanation do not share the same rate-limiting step on Pd, and that the two pathways are probably catalyzed at different surface sites. Measured reaction orders in CO<sub>2sub> and H<sub>2sub> pressures were similar over the two catalysts, suggesting that the reaction mechanism for each pathway does not change with particle size. In accordance, the DRIFTS results reveal that the prevalent surface species and their evolution patterns are comparable on the two catalysts during transient and steady-state experiments, switching feed gases among CO<sub>2sub>, H<sub>2sub> and CO<sub>2sub>+H>2sub>. The DRIFTS and MS results also demonstrate that no direct dissociation of CO<sub>2sub> takes place over the two catalysts, and that CO<sub>2sub> has to first react with surface hydroxyls on the oxide support. The thus-formed bicarbonates react with dissociatively adsorbed hydrogen on Pd particles to produce adsorbed formate species (bifunctional catalyst: CO<sub>2sub> activation on the oxide support, and H<sub>2sub> dissociation on the metal particles). Formates near the Pd particles (most likely at the metal/oxide interface) can react rapidly with adsorbed H

  18. Pressure dependence of the elastic constants and vibrational anharmonicity of Pd sub 3 sub 9 Ni sub 1 sub 0 Cu sub 3 sub 0 P sub 2 sub 1 bulk metallic glass

    CERN Document Server

    Wang Li; Sun, L L; Wang, W H; Wang, W K

    2003-01-01

    The pressure dependence of the acoustic velocities of a Pd sub 3 sub 9 Ni sub 1 sub 0 Cu sub 3 sub 0 P sub 2 sub 1 bulk metallic glass have been investigated up to 0.5 GPa at room temperature with the pulse echo overlap method. Two independent second-order elastic coefficients C sub 1 sub 1 and C sub 4 sub 4 and their pressure derivatives are yielded. The vibrational anharmonicity is shown by calculating both the acoustic mode Grueneisen parameters in the long-wavelength limit and the thermal Grueneisen parameter, and this result is compared with that for the Pd sub 4 sub 0 Ni sub 4 sub 0 P sub 2 sub 0 bulk glass.

  19. Metal organic vapour phase epitaxy of strained InP-Ga sub x In sub 1 sub - sub x As sub y P sub 1 sub - sub y quantum well lasers

    CERN Document Server

    Smith, A D

    1998-01-01

    that describes the optimisation in growth conditions to suppress thickness modulations, enabling larger numbers of planar wells and barriers to be grown. The effects of compositional clustering can be minimised by using higher growth temperatures and selecting alloy compositions outside the miscibility gap. In contrast, strain relief via the expansion and contraction of lattice planes is eliminated by using lower growth temperatures and higher group V pre-cursor gas flows. The growth conditions which best overcome these two effects in +-1% Ga sub x ln sub 1 sub - sub x As and +-1% Ga sub x In sub 1 sub - sub x As sub y P sub 1 sub - sub y strain-compensated, multiple-quantum well, laser structures are described. The strain relief behaviour of non-compensated InP-Ga sub x In sub 1 sub - sub x As sub y P sub 1 sub - sub y based, multiple-quantum well structures is presented. Dislocation generation is identified as the primary strain relief mechanism in Ga sub x In sub 1 sub - sub x As sub y P sub 1 sub - sub y ...

  20. Observation of three different ferromagnetic phases with predictable T sub c s in La sub 2 MnCo sub 0 sub . sub 5 Ni sub 0 sub . sub 5 O sub 6

    CERN Document Server

    Joly, V L J; Joy, P A

    2003-01-01

    The perovskite-type oxide La sub 2 MnCo sub 0 sub . sub 5 Ni sub 0 sub . sub 5 O sub 6 has been found to form in three different ferromagnetic phases with different transition temperatures, when a low-temperature synthesized sample is annealed at different temperatures. The interesting magnetic behaviour of the compound is due to the combination of different spin states of Mn, Co and Ni in the different phases of the compound. The magnetic transition temperatures of the three phases of the compound can be predicted from the T sub c s of La sub 2 MnCoO sub 6 and La sub 2 MnNiO sub 6. (letter to the editor)

  1. High-Pressure Study of Perovskite-Like Organometal Halide: Band-Gap Narrowing and Structural Evolution of [NH <sub>3sub> -(CH <sub>2sub> )<sub>4sub> -NH<sub>3sub> ]CuCl<sub>4sub>

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qian; Li, Shourui; Wang, Kai; Quan, Zewei; Meng, Yue; Zou, Bo

    2017-01-10

    Searching for nontoxic and stable perovskite-like alternatives to lead-based halide perovskites for photovoltaic application is one urgent issue in photoelectricity science. Such exploration inevitably requires an effective method to accurately control both the crystalline and electronic structures. This work applies high pressure to narrow the band gap of perovskite-like organometal halide, [NH<sub>3sub>-(CH>2sub>)>4sub>-NH>3sub>]CuCl>4sub> (DABCuCl4), through the crystalline-structure tuning. The band gap keeps decreasing below ~12 GPa, involving the shrinkage and distortion of CuCl<sub>4sub>2–. Inorganic distortion determines both band-gap narrowing and phase transition between 6.4 and 10.5 GPa, and organic chains function as the spring cushion, evidenced by the structural transition at ~0.8 GPa. The supporting function of organic chains protects DABCuCl<sub>4sub> from phase transition and amorphization, which also contributes to the sustaining band-gap narrowing. This work combines crystal structure and macroscopic property together and offers new strategies for the further design and synthesis of hybrid perovskite-like alternatives.

  2. Transport properties of Ru-doped La sub 1 sub . sub 8 sub 5 Sr sub 0 sub . sub 1 sub 5 CuO sub 4 and the effect of carrier concentration compensation

    CERN Document Server

    Xiong, Y M; Luo, X G; Zhang, H T; Wang, C H; Li, S Y; Chen, X H

    2003-01-01

    This paper is a study of the structure and transport properties of Ru-doped La sub 1 sub . sub 8 sub 5 Sr sub 0 sub . sub 1 sub 5 CuO sub 4. It is found that Ru substitution for Cu has two effects. (1) Ru doping introduces disorder into the system, which causes a metal-insulator transition with high localization. (2) There is a hole-filling effect due to the valence of the Ru ion being higher than that of the Cu ion. Increase of the strontium content could compensate for the imbalance of valence caused by doping with the high-valence Ru ion. A universal curve for T sub c versus the number of holes per Cu site is observed for the La sub 2 sub - sub y Sr sub y Cu sub 1 sub - sub x Ru sub x O sub 4 system, indicating that a rigid-band model holds and T sub c correlates with features in the density of states, such as a Van Hove singularity.

  3. Magnetic phase transitions in TbFe sub 2 Al sub 1 sub 0 , HoFe sub 2 Al sub 1 sub 0 and ErFe sub 2 Al sub 1 sub 0

    CERN Document Server

    Reehuis, M; Krimmel, A; Scheidt, E W; Stüsser, N; Loidl, A; Jeitschko, W

    2003-01-01

    The magnetic order of the orthorhombic aluminides TbFe sub 2 Al sub 1 sub 0 , HoFe sub 2 Al sub 1 sub 0 and ErFe sub 2 Al sub 1 sub 0 (space group Cmcm) has been studied by specific heat and magnetic measurements, as well as by neutron powder diffraction down to 100 mK and in external fields up to 5 T. Only the rare-earth ions carry a magnetic moment. At T = 1.5 K the terbium moments in TbFe sub 2 Al sub 1 sub 0 show a square-wave modulated magnetic order with wavevector k = (0, 0.7977, 0) and a moment direction parallel to the a-axis. At a critical field of H sub c sub 1 = 0.9 T one of ten spins is forced to flip, going into an intermediate ferrimagnetic phase that is stable up to the critical field H sub c sub 2 = 1.8 T. Above this field finally all the rest of the spins flip, resulting in a ferromagnetic order of the terbium moments. ErFe sub 2 Al sub 1 sub 0 orders antiferromagnetically below T sub N 1.77(7) K with a similar magnetic structure characterized by a wavevector k (0, approx 0.8, 0). In contras...

  4. Structurally induced magnetization in a La<sub>2/3sub>Sr>4/3sub>MnO>4sub> superlattice

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Amish B. [Argonne National Lab. (ANL), Argonne, IL (United States); Nelson-Cheeseman, Brittany B. [Argonne National Lab. (ANL), Argonne, IL (United States); Subramanian, Ganesh [Arizona State Univ., Tempe, AZ (United States); Bhattacharya, Anand [Argonne National Lab. (ANL), Argonne, IL (United States); Spence, John C.H. [Arizona State Univ., Tempe, AZ (United States)

    2012-03-16

    A structural transition has been observed in a digital superlattice of La<sub>2/3sub>Sr>4/3sub>MnO>4sub>, which is correlated to a magnetization enhancement upon cooling the sample. The artificial superlattices were grown layer-by-layer using ozone-assisted molecular beam epitaxy (MBE). Electron diffraction experiments show a phase transition below 150K in nanopatches of the superlattice, which coincides with an enhanced magnetization starting below 110K. Furthermore, atomic scale electron energy loss spectroscopy (EELS) shows changes in the Mn L<sub>2,3sub> and O K edges, which are related to valence, strain, and the atomic coordination within nanopatches. Atomic resolution image and EELS showing variations of oxygen and lanthanum signature edges in a La<sub>2/3sub>Sr>4/3sub>MnO>4sub> supperlattice.

  5. Sub-threshold synchronizer

    NARCIS (Netherlands)

    Zhou, J.; Ashouei, M.; Kinniment, D.; Huisken, J.; Russell, G.; Yakovlev, A.

    2011-01-01

    Sub-threshold operation has been proven to be very effective to reduce the power consumption of circuits when high performance is not required. Future low power systems on chip are likely to consist of many sub-systems operating at different frequencies and VDDs from super-threshold to sub-threshold

  6. Structural and electronic properties of BAs and B {sub x} Ga{sub 1-} {sub x} As, B {sub x} In{sub 1-} {sub x} As alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chimot, N. [Laboratoire d' Etude des Nanostructures a Semiconducteurs UMR6082, INSA de Rennes, 20 Avenue des Buttes de Coesmes, CS 14315, F34043 Rennes Cedex (France); Even, J. [Laboratoire d' Etude des Nanostructures a Semiconducteurs UMR6082, INSA de Rennes, 20 Avenue des Buttes de Coesmes, CS 14315, F34043 Rennes Cedex (France)]. E-mail: jacky.even@insa-rennes.fr; Folliot, H. [Laboratoire d' Etude des Nanostructures a Semiconducteurs UMR6082, INSA de Rennes, 20 Avenue des Buttes de Coesmes, CS 14315, F34043 Rennes Cedex (France); Loualiche, S. [Laboratoire d' Etude des Nanostructures a Semiconducteurs UMR6082, INSA de Rennes, 20 Avenue des Buttes de Coesmes, CS 14315, F34043 Rennes Cedex (France)

    2005-07-15

    Structural and electronic properties of the BAs compound and B {sub x} Ga{sub 1-} {sub x} As, B {sub x} In{sub 1-} {sub x} As alloys are studied using first principles calculations. New results on elastic constants, acoustic phonons and optical phonons frequencies are reported. The 4x4 Kane's interaction matrix is calculated in order to ease simulations of optoelectronic devices. Effective masses and Luttinger parameters for the valence bands are calculated. B {sub x} Ga{sub 1-} {sub x} As and B {sub x} In{sub 1-} {sub x} As alloys are simulated using the virtual crystal approximation (VCA). The B {sub x} Ga{sub 1-} {sub x} As alloy lattice-matched to GaP substrate is found to be an indirect band gap semiconductor. The B {sub x} In{sub 1-} {sub x} As alloys lattice-matched to InP and GaAs substrates, are found to be direct band gap semiconductors. The B {sub x} In{sub 1-} {sub x} As alloy is proposed as an alternative solution for epitaxial growth of nanostructures for electronic (field effect transistors) and optoelectronic (lasers, saturable absorbers) devices on InP substrate.

  7. Features of pseudogap and superconductivity states of YBa sub 2 Cu sub 3 O sub 7 sub - sub x

    CERN Document Server

    Misochko, O V; Dekorsy, T; Helm, M

    2002-01-01

    The relaxation dynamics of the lattice and low-energy quasi-particles of the YBa sub 2 Cu sub 3 O sub 7 sub - sub x superconductor is studied through the light reflection method within the wide temperature range. It is shown that for T > T sub c there exist two areas of temperature with qualitatively and quantitatively different excitation dynamics and the transition between these areas is of the hysteresis character. It is established also, that the character of the change in the relaxation dynamics of the charge carriers in the superconducting state indicates the anisotropic gap with zeroes on the Fermi surface

  8. Effect of TiO<sub>2sub> content on the crystallization and the color of (ZrO<sub>2sub>,TiO>2sub>)-doped Li<sub>2sub>O-Al>2sub>O>3sub>-SiO>2sub> glasses

    Energy Technology Data Exchange (ETDEWEB)

    Chavoutier, M.; Caurant, D.; Majérus, O.; Boulesteix, R.; Loiseau, P.; Jousseaume, C.; Brunet, E.; Lecomte, E. [CNRS-UMR; (Eurokera); (Saint-Gobain)

    2014-02-18

    Glass–ceramics formed by controlled crystallization of Li<sub>2sub>O–Al>2sub>O>3sub>–SiO>2sub> (LAS) parent glasses are well-known for their low thermal expansion and transparency. In order to promote bulk crystallization, it is necessary to add nucleating agents like TiO<sub>2sub> and ZrO<sub>2sub> to the glass composition leading to ZrTiO<sub>4sub> nuclei during heating, followed by the crystallization of a β-quartz phase that transforms into β-spodumene at higher temperature. Generally, these glass–ceramics present a yellowish-brown coloration whose intensity increases with the crystallization rate and that is partly due to coloring elements like titanium. In this study, we investigated the origin of the evolution of the color of LAS glasses and glass–ceramics by varying the TiO<sub>2sub> concentration. To do this, several TiO<sub>2sub>-bearing LAS glasses (with TiO<sub>2sub> ranging from 0 to 4 mol% and 1 mol% ZrO<sub>2sub>) were prepared and heat treated at a given temperature (925 °C) to study the impact of the TiO<sub>2sub> concentration on their crystallization behavior and their color. The crystallization and microstructure of LAS glasses and glass–ceramics were studied by DTA, XRD and TEM whereas their structure was investigated by EPR, optical and X-ray absorption spectroscopies. From all the results obtained, the evolution of the optical absorption and coloration of LAS glasses and glass–ceramics was mainly explained by Ti4+–O2- charge transfer (glasses) and by gap absorption and Rayleigh scattering of nanocrystals (glass–ceramics).

  9. Synchrotron X-ray scattering study of the substrate effects on relaxor Pb(Mg sub 1 sub / sub 3 Nb sub 2 sub / sub 3 sub -delta)O sub 3 /SrTiO sub 3 thin films

    CERN Document Server

    Seo, S H; Noh, D Y; Yamada, Y; Wasa, K

    2002-01-01

    Perovskite Pb(Mg sub 1 sub / sub 3 Nb sub 2 sub / sub 3 sub - subdelta)O sub 3 (PMN) thin films are grown epitaxially on on-axis SrTiO sub 3 (001) (STO), vicinal SrTiO sub 3 (001), and MgO (001) substrates by radio-frequency magnetron sputtering. The substrate effects on the structure of PMN thin films have been studied using synchrotron X-ray scattering technique. Initially PMN films grow in two-dimensional planar layers on the STO substrates, while they grow in the form of three-dimensional (3D) islands on the MgO substrate. The surface steps on the vicinal STO encourage the 3D island growth as the film thickness increases. We also found an unexpected monoclinic phase in PMN/STO and PMN/vicinal-STO films, which has been reported in bulk Pb(Mg sub 1 sub / sub 3 Nb sub 2 sub / sub 3)O sub 3 -35%PbTiO sub 3 solid solution. With increasing the film thickness, the unit cell structure of PMN films transforms from tetragonal to other structures as the strain relaxes. (author)

  10. Magnetic phase transitions in the anion-deficient La sub 1 sub - sub x Ba sub x MnO sub 3 sub - sub x sub / sub 2 (0 <= x <= 0.50) manganites

    CERN Document Server

    Trukhanov, S V; Bushinsky, M V; Troyanchuk, I O; Szymczak, H

    2003-01-01

    The crystal structure, magnetization and electrical resistivity properties of the anion-deficient La sub 1 sub - sub x Ba sub x MnO sub 3 sub - sub x sub / sub 2 (0 = 0.03) being a mixture of antiferromagnetic and ferromagnetic phases. At x >= 0.12 competition between antiferromagnetic and ferromagnetic interactions leads to a cluster spin glass state appearance with a magnetic moment freezing temperature of approx 45 K. The dominant magnetic phase for x >= 0.22 is supposed to be antiferromagnetic. All the reduced samples are semiconductors and show considerable magnetoresistance over a wide temperature range in a magnetically ordered state. The largest magnetoresistance (approx 34% in a 9 kOe field at liquid nitrogen temperatures) is observed for an x = 0.30 sample. The magnetic phase diagram of La sub 1 sub - sub x sup 3 sup + Ba sub x sup 2 sup + Mn sup 3 sup + O sub 3 sub - sub x sub / sub 2 sup 2 sup - manganites has been established by combining the results of magnetic and electrical measurements. The r...

  11. Influence of structural disorder on the optical and transport properties of Co sub 0 sub . sub 5 sub 0 Ti sub 0 sub . sub 5 sub 0 alloy films

    CERN Document Server

    Kim, K W; Rhee, J Y; Kudryavtsev, Y V; Ri, H C

    2000-01-01

    Co sub 0 sub . sub 5 sub 0 Ti sub 0 sub . sub 5 sub 0 alloy films with a total thickness of about 100 nm were prepared by flash evaporation of the crushed alloy powders onto heated (730 K for the ordered state) and LN sub 2 -cooled (150 K for the disordered state) substrates. Structural analysis of the films was performed by suing transmission electron microscopy. The optical conductivity (OC) of the samples was measured at room temperature in a spectral range of 265 -2500 nm (4.7 - 0.5 eV). The resistivity measurements were carried out by using the four-probe technique in a temperature range of 4.2 - 300 K. The experimental OC spectra for the Co sub 0 sub . sub 5 sub 0 Ti sub 0 sub . sub 5 sub 0 alloys show the most significant change in the infrared region upon the order-disorder transformation. The structural disorder in the Co sub 0 sub . sub 5 sub 0 Ti sub 0 sub . sub 5 sub 0 alloy film leads to a change in the sign of the temperature coefficient of the resistivity from positive to negative. The observed...

  12. Tuning of Photoluminescence by Cation Nanosegregation in the (CaMg) <sub>x> (NaSc) <sub>1–xsub> Si <sub>2sub> O <sub>6sub> Solid Solution

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhiguo; Liu, Guokui; Wen, Jianguo; Mei, Zhigang; Balasubramanian, Mahalingam; Molokeev, Maxim S.; Peng, Licong; Gu, Lin; Miller, Dean J.; Liu, Quanlin; Poeppelmeier, Kenneth R.

    2016-02-03

    Controlled photoluminescence tuning is important for the optimization and modification of phosphor materials. Herein we report an isostructural solid solution of (CaMg)<sub>x(NaSc)>1-xsub>Si>2sub>O>6sub> (0 < x < 1) in which cation nanosegregation leads to the presence of two dilute Eu2+ centers. The distinct nanodomains of isostructural (CaMg)Si<sub>2sub>O>6sub> and (NaSc)Si<sub>2sub>O>6sub> contain a proportional number of Eu2+ ions with unique, independent spectroscopic signatures. Density functional theory calculations provided a theoretical understanding of the nanosegregation and indicated that the homogeneous solid solution is energetically unstable. It is shown that nanosegregation allows predictive control of color rendering and therefore provides a new method of phosphor development.

  13. Semiconducting Ba <sub>3sub> Sn <sub>3sub> Sb <sub>4sub> and Metallic Ba <sub>7–xsub> Sn <sub>11sub> Sb <sub>15–ysub> ( x = 0.4, y = 0.6) Zintl Phases

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Haijie [Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States; Materials; Narayan, Awadhesh [Department of Physics, University of Illinois at Urbana−Champaign, Champaign, Illinois 61801, United States; Stoumpos, Constantinos C. [Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States; Zhao, Jing [Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States; Han, Fei [Materials; Chung, Duck Young [Materials; Wagner, Lucas K. [Department of Physics, University of Illinois at Urbana−Champaign, Champaign, Illinois 61801, United States; Kwok, Wai-Kwong [Materials; Kanatzidis, Mercouri G. [Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States; Materials

    2017-11-08

    We report the discovery of two ternary Zintl phases Ba<sub>3sub>Sn>3sub>Sb>4sub> and Ba<sub>7-xsub>Sn>11sub>Sb>15-ysub>, (x = 0.4, y = 0.6). Ba<sub>3sub>Sn>3sub>Sb>4sub> adopts the monoclinic space group P2<sub>1sub>/c with a = 14.669(3) Å, b = 6.9649(14) Å, c = 13.629(3) Å, and β = 104.98(3)°. It features a unique corrugated two-dimensional (2D) structure consisting of [Sn<sub>3sub>Sb>4sub>]6- layers extending along the ab plane with Ba2+ atoms sandwiched between them. The non-stoichiometric Ba<sub>6.6sub>Sn>11sub>Sb>14.4sub> has a complex one-dimensional (1D) structure adopting the orthorhombic space group Pnma, with unit cell parameters a = 37.964(8) Å, b = 4.4090(9) Å and c = 24.682(5) Å. It consists of large double Sn-Sb ribbons separated by Ba2+ atoms. Ba3Sn3Sb4 is an n-type semiconductor which has a narrow energy gap of ~0.18 eV and a room temperature carrier concentration of ~4.2 × 1018 cm-3. Ba<sub>6.6sub>Sn>11sub>Sb>14.4sub> is determined to be a metal with electrons being the dominant carriers.

  14. A Rutile Chevron Modulation in Delafossite-Like Ga <sub>3–xsub> In <sub>3sub> Ti <sub>x> O <sub>9+x/2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Rickert, Karl; Boullay, Philippe; Malo, Sylvie; Caignaert, Vincent; Poeppelmeier, Kenneth R.

    2016-05-02

    The structure solution of the modulated, delafossite-related, orthorhombic Ga<sub>3–xsub>In>3sub>TixO>9+x/2sub> for x = 1.5 is reported here in conjunction with a model describing the modulation as a function of x for the entire system. Previously reported structures in the related A<sub>3–xsub>In>3sub>TixO>9+x/2sub> (A = Al, Cr, or Fe) systems use X-ray diffraction to determine that the anion lattice is the source of modulation. Neutron diffraction, with its enhanced sensitivity to light atoms, offers a route to solving the modulation and is used here, in combination with precession electron diffraction tomography (PEDT), to solve the structure of Ga<sub>1.5sub>In>3sub>Ti>1.5sub>O>9.75sub>. We construct a model that describes the anion modulation through the formation of rutile chevrons as a function of x. This model accommodates the orthorhombic phase (1.5 ≤ x ≤ 2.1) in the Ga<sub>3-xsub>In>3sub>TixO>9+x/2sub> system, which transitions to a biphasic mixture (2.2 ≤ x ≤ 2.3) with a monoclinic, delafossite-related phase (2.4 ≤ x ≤ 2.5). The optical band gaps of this system are determined, and are stable at ~3.4 eV before a ~0.4 eV decrease between x = 1.9 and 2.0. After this decrease, stability resumes at ~3.0 eV. Resistance to oxidation and reduction is also presented.

  15. Na{sub 2}O-B{sub 2}O{sub 3}-SiO{sub 2} glass modified by Al{sub 2}O{sub 3}, TiO{sub 2}, ZrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Procyk, B.; Stoch, L.; Dabrowska, A.; Haniuk, I. [Akademia Gorniczo-Hutnicza, Cracow (Poland)

    1993-12-31

    The Na{sub 2}O-B{sub 2}O{sub 3}-SiO{sub 2} system with additions Al{sub 2}O{sub 3}, TiO{sub 2}, ZrO{sub 2} was examined. The conditions of thermal and chemical treatment necessary to obtain porous glasses were optimized. Their structure and basic physicochemical properties were investigated. (author). 4 refs, 5 figs, 1 tab.

  16. Flux Crystal Growth of the RE<sub>2sub>Ru>3sub>Ge>5sub> (RE = La, Ce, Nd, Gd, Tb) Series and Their Magnetic and Metamagnetic Transitions

    Energy Technology Data Exchange (ETDEWEB)

    Bugaris, Daniel E. [Materials Science; Malliakas, Christos D. [Materials Science; Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States; Bud’ko, Sergey L. [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States; Division of Materials Science & amp, Engineering, Ames Laboratory, Ames, Iowa 50011, United States; Calta, Nicholas P. [Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States; Chung, Duck Young [Materials Science; Kanatzidis, Mercouri G. [Materials Science; Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States

    2017-11-16

    Previously synthesized only as powders, single crystals of the RE<sub>2sub>Ru>3sub>Ge>5sub> (RE = La, Ce, Nd, Gd, Tb) series of compounds have been now been obtained from molten In. These materials crystallize with the U<sub>2sub>Co>3sub>Si>5sub>-type structure in orthorhombic space group Ibam with lattice parameters a ~ 10.00-9.77 Å (La-Tb), b ~ 12.51-12.35 Å, and c ~ 5.92-5.72 Å. The structure is a three-dimensional framework consisting of RuGe<sub>5sub> and RuGe<sub>6sub> units, as well as Ge-Ge zigzag chains. This structure type, along with the other five (Sc<sub>2sub>Fe>3sub>Si>5sub>, Lu<sub>2sub>Co>3sub>Si>5sub>, Y<sub>2sub>Rh>3sub>Sn>5sub>, Yb<sub>2sub>Ir>3sub>Ge>5sub>, and Yb<sub>2sub>Pt>3sub>Sn>5sub>) to compose the RE<sub>2sub>T>3sub>X>5sub> phase space, are discussed in depth. For the three compounds with RE = Nd, Gd, and Tb, multiple magnetic transitions and metamagnetic behavior are observed. Electronic band structure calculations performed on La<sub>2sub>Ru>3sub>Ge>5sub> indicate that these materials have a negative band gap and are semimetallic in nature.

  17. Spectroscopy and tunable mid-infrared lasing of a novel gain medium: Cr sup 2 sup + doped Cd sub 0 sub . sub 8 sub 5 Mn sub 0 sub . sub 1 sub 5 Te

    CERN Document Server

    Seo, J T; Trivedi, S B; Kutcher, S W; Chen, R J; Wang, C C; Zong, H; Boyd, P R; Tardiff, W

    1999-01-01

    A novel mid-infrared transition-metal laser has been developed based on chromium (II)-doped Cd sub 0 sub . sub 8 sub 5 Mn sub 0 sub . sub 1 sub 5 Te. The characteristic spectroscopy features of Cr sup 2 sup + : Cd sub 0 sub . sub 8 sub 5 Mn sub 0 sub . sub 1 sub 5 Te are large absorption and emission cross sections (approx 10 sup - sup 1 sup 8 cm sup 2), a predicted absence of excited state absorption (ESA), and a broad emission band extending from 2.1 approx 3.5 mu m. The broad emission band makes Cr sup 2 sup + : Cd sub 0 sub . sub 8 sub 5 Mn sub 0 sub . sub 1 sub 5 Te very attractive for the development of a widely tunable mid-infrared laser. In initial studies, a laser tunability from 2.3 to 2.75 mu m has been demonstrated with a full width at half maximum of 2.3 nm. A larger tuning range seems possible with the appropriate optics. The highest slope efficiency achieved for a pulsed (2 Hz) free-running laser was 44.2%.

  18. Effects of stoichiometries on the positron distribution in Si sub 1 sub - sub x sub - sub y Ge sub x C sub y alloys

    CERN Document Server

    Soudini, B; Abid, H; Sehil, M

    2003-01-01

    The effect of alloying on the positron distribution in Si sub 1 sub - sub x sub - sub y Ge sub x C sub y alloys is reported. Our computations of the thermalized positron densities are based on the independent particle method coupled with the empirical pseudopotential method to derive the positron and electron wave functions, respectively. Initial results show a clear symmetrical positron charge distribution relative to the bond centre, a quite similar situation that was found in the IV groups. Since the minimum band gaps were found to be very sensitive to the carbon as well as the germanium concentration variations, this has an immediate consequence on the positron densities, where we find a deviation from linearity. This illustrative result was an indication of the alloying effect in this system (bowing effect). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  19. Atomic ordering and magnetic properties of non-stoichiometric double-perovskite Sr sub 2 Fe sub x Mo sub 2 sub - sub x O sub 6

    CERN Document Server

    Liu, G Y; Feng, X M; Yang, H F; Ouyang, Z W; Liu, W F; Liang, J K

    2003-01-01

    The crystal structure and magnetic properties of a new series of ordered double-perovskite oxides Sr sub 2 Fe sub x Mo sub 2 sub - sub x O sub 6 (0.8 <= x <= 1.5) have been studied. The crystal structure changes from a tetragonal I4/mmm lattice to a cubic Fm3-bar m lattice around x = 1.2. The degree of ordering in Sr sub 2 Fe sub x Mo sub 2 sub - sub x O sub 6 exhibits a maximal at x = 0.95 and decreases as x deviates from 0.95. The saturated magnetization increases from x = 0.8 to 0.95 and then decreases from x = 0.95 to 1.5. The Curie temperature exhibits an abrupt drop around x = 1.2, where the structural transition takes place. These complex behaviours are strongly correlated to antisite defect concentration in the compounds.

  20. Preparation, crystallography, magnetic and magnetothermal properties of Ce<sub>5sub>SixGe>4-xsub> alloys

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaraghavan, Rangarajan [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    An investigation of the crystal structure and the phase relationships in the Ce<sub>5sub>Si>4-xsub>Gex> system has been carried out. The crystal structures of the single phase intermetallics were characterized using X-ray powder diffraction and subsequent refinement employing the Rietveld analysis technique was performed. The intermetallic system was found to crystallize in three distinct crystal structures. The Ce<sub>5sub>Si>4sub>-based solid solution extends from x = 0 to x = 2.15 and it was found to crystallize in the well-known Zr<sub>5sub>Si>4sub>-type tetragonal structure. The germanium rich alloys, where 3.1 ≤} x ≤ 4, crystallized in the Sm<sub>5sub>Ge>4sub>-type orthorhombic structure. The crystal structure of the intermediate phase, when 2.35 ≤ x ≤ 2.8, was found out to be of the Gd<sub>5sub>Si>2sub>Ge>2sub>-type monoclinic structure. Microhardness tests were conducted on the samples in order to probe the trend in mechanical properties in this alloy system as a function of Ge concentration. The magnetic, thermal and magnetocaloric properties of the Ce<sub>5sub>Si>4-xsub>Gex> alloy system have been investigated for x = 0, 1.0, 1.8, 2.5, 2.8, 3.5, 3.8 and 4.0. The phases with x = 0, 1.0 and 1.8 crystallize in the tetragonal Zr<sub>5sub>Si>4sub> structure and those with x = 2.5, 2.8 form in the Gd<sub>5sub>Si>2sub>Ge>2sub>-type monoclinic structure. The alloys with x = 3.5, 3.8 and 4.0 crystallize in the Sm<sub>5sub>Ge>4sub>-type orthorhombic structure. The Curie temperature of the tetragonal phases increases with increasing Ge content. The ordering temperatures of the monoclinic and orthorhombic phases remain nearly unaffected by the composition, with the Curie temperatures of the latter slightly higher than those of the former. All the alloys display evidence of antiferromagnetic interactions in the ground state. The orthorhombic and the

  1. Thermoresponsive behaviour of AM sub 2 O sub 8 materials

    CERN Document Server

    Allen, S

    2003-01-01

    This thesis investigates the synthesis and structural characterisation of AM sub 2 O sub 8 phases, many of which show negative thermal expansion (NTE); relevant literature is reviewed in Chapter One. Chapter Two describes the synthesis, structure solution, and mechanistic role of a new family of low-temperature (LT) orthorhombic AM sub 2 O sub 8 polymorphs (A sup I sup V = Zr, Hf; M sup V sup I = Mo, W). These materials are key intermediates in the preparation of cubic AM sub 2 O sub 8 phases from AM sub 2 O sub 7 (OH) sub 2 (H sub 2 O) sub 2. The structure of LT-AM sub 2 O sub 8 has been elucidated by combined laboratory X-ray and neutron powder diffraction. Variable temperature X-ray diffraction (VTXRD) studies have shown LT-AMo sub 2 O sub 8 phases exhibit anisotropic NTE. LT-ZrMo sub 2 O sub 8 has been shown to undergo spontaneous rehydration, allowing preparation of ZrMo sub 2 O sub 7 (OD) sub 2 (D sub 2 O) sub 2 and assignment of D sub 2 O/OD positions within the structure by neutron diffraction. Using ...

  2. Magnetoinduced valence transition in EuNi sub 2 (Si sub 1 sub - sub x Ge sub x) sub 2 in fields up to 500 T

    CERN Document Server

    Platonov, V V; Selemir, V D; Shiga, M

    2002-01-01

    One measured critical fields of magnetic field induced valent transition in EuNi sub 2 (Si sub 1 sub - sub x Ge sub x) sub 2 compound within intermediate valence range with x 0.5-0.75. Measurements of magnetic susceptibility were conducted under helium temperature in up to 600 T fields. It is shown that magnitude of critical field increases linearly with decrease of germanium concentration

  3. A reduced graphene oxide/Co<sub>3sub>O>4sub> composite for supercapacitor electrode

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Chengcheng; Li, Ming; Zhi, Mingjia; Manivannan, Ayyakkannu; Wu, Nianqiang

    2013-03-01

    20 nm sized Co<sub>3sub>O>4sub> nanoparticles are in-situ grown on the chemically reduced graphene oxide (rGO) sheets to form a rGO-Co<sub>3sub>O>4sub> composite during hydrothermal processing. The rGO-Co<sub>3sub>O>4sub> composite is employed as the pseudocapacitor electrode in the 2 M KOH aqueous electrolyte solution. The rGOCo<sub>3sub>O>4sub> composite electrode exhibits a specific capacitance of 472 F/g at a scan rate of 2 mV/s in a two-electrode cell. 82.6% of capacitance is retained when the scan rate increases to 100 mV/s. The rGOCo<sub>3sub>O>4sub> composite electrode shows high rate capability and excellent long-term stability. It also exhibits high energy density at relatively high power density. The energy density reaches 39.0 Wh/kg at a power density of 8.3 kW/kg. The super performance of the composite electrode is attributed to the synergistic effects of small size and good redox activity of the Co<sub>3sub>O>4sub> particles combined with high electronic conductivity of the rGO sheets.

  4. Ternary gallides RE{sub 4}Rh{sub 9}Ga{sub 5}, RE{sub 5}Rh{sub 12}Ga{sub 7} and RE{sub 7}Rh{sub 18}Ga{sub 11} (RE=Y, La-Nd, Sm, Gd, Tb). Intergrowth structures with MgCu{sub 2} and CaCu{sub 5} related slabs

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, Stefan; Rodewald, Ute C.; Poettgen, Rainer [Univ. Muenster (Germany). Inst. fuer Anorganische und Analytische Chemie; Janka, Oliver [Univ. Oldenburg (Germany). Inst. fuer Chemie

    2017-07-01

    Fourteen ternary gallides RE{sub 4}Rh{sub 9}Ga{sub 5}, RE{sub 5}Rh{sub 12}Ga{sub 7} and RE{sub 7}Rh{sub 18}Ga{sub 11} (RE=Y, La-Nd, Sm, Gd, Tb) were synthesized from the elements by arc-melting, followed by different annealing sequences either in muffle or induction furnaces. The samples were characterized through Guinier powder patterns and the crystal structures of Ce{sub 4}Rh{sub 9}Ga{sub 5}, Ce{sub 5}Rh{sub 12}Ga{sub 7}, Ce{sub 7}Rh{sub 18}Ga{sub 11}, Nd{sub 5}Rh{sub 10.44(4)}Ga{sub 8.56(4)}, Nd{sub 4}Rh{sub 9}Ga{sub 5} and Gd{sub 4}Rh{sub 9}Ga{sub 5} were refined from single crystal X-ray diffractometer data. The new gallides are the n=2, 3 and 5 members of the RE{sub 2+n} Rh{sub 3+3n} Ga{sub 1+2n} structure series in the Parthe intergrowth concept. The slabs of these intergrowth structures derive from the cubic Laves phase MgCu{sub 2} (Mg{sub 2}Ni{sub 3}Si as ternary variant) and CaCu{sub 5} (CeCo{sub 3}B{sub 2} as ternary variant). Only the Nd{sub 5}Rh{sub 10.44(4)}Ga{sub 8.56(4)} crystal shows Rh/Ga mixing within the Laves type slabs. Magnetic susceptibility measurements reveal Pauli paramagnetism for Y{sub 4}Rh{sub 9}Ga{sub 5} and Curie-Weiss paramagnetism for Gd{sub 4}Rh{sub 9}Ga{sub 5} and Tb{sub 4}Rh{sub 9}Ga{sub 5}. Low-temperature data show ferromagnetic ordering at T{sub C}=78.1 (Gd{sub 4}Rh{sub 9}Ga{sub 5}) and 55.8 K (Tb{sub 4}Rh{sub 9}Ga{sub 5}).

  5. Pressure-induced instability of magnetic order in Kondo-lattice system. Neutron diffraction study of the pseudo-binary alloy system Ce(Ru sub 0 sub . sub 9 sub 0 Rh sub 0 sub . sub 1 sub 0) sub 2 (Si sub 1 sub - sub y Ge sub y) sub 2

    CERN Document Server

    Watanabe, K; Kanadani, C; Taniguchi, T; Kawarazaki, S; Uwatoko, Y; Kadowaki, H

    2003-01-01

    Neutron diffraction experiments have been carried out to study the nature of the magnetic order of the pseudo-binary alloy system Ce(Ru sub 0 sub . sub 9 sub 0 Rh sub 0 sub . sub 1 sub 0) sub 2 (Si sub 1 sub - sub y Ge sub y) sub 2. Response of the ordered atomic magnetic moment, mu, the transition temperature, T sub N , and the magnitude of the magnetic modulation vector, q, to the chemical pressure and also to the applied hydrostatic pressure, P, were examined at low temperatures. When y changes, all of mu, T sub N and q show a sudden alteration of the manner of the y-dependence at around y - 0.08. The P-dependence of q shows quite different features for different y's of 0.0, 0.2 and 0.25. On the basis of these observations the possibility of a pressure-induced alternation of the magnetic regime of the order is discussed. (author)

  6. Measuring CO <sub>2sub> and N <sub>2sub> O Mass Transfer into GAP-1 CO <sub>2sub> –Capture Solvents at Varied Water Loadings

    Energy Technology Data Exchange (ETDEWEB)

    Whyatt, Greg A.; Zwoster, Andy; Zheng, Feng; Perry, Robert J.; Wood, Benjamin R.; Spiry, Irina; Freeman, Charles J.; Heldebrant, David J.

    2017-04-12

    This paper investigates the CO<sub>2sub> and N<sub>2sub> O absorption behavior in the water-lean gamma amino propyl (GAP)-1/TEG solvent system using a wetted-wall contactor. Testing was performed on a blend of GAP-1 aminosilicone in triethylene glycol at varied water loadings in the solvent. Measurements were made with CO<sub>2sub> and N<sub>2sub> O at representative lean (0.04 mol CO<sub>2sub>/mol alkalinity), middle (0.13 mol CO<sub>2sub> /mol alkalinity) and rich (0.46 mol CO<sub>2sub> /mol alkalinity) solvent loadings at 0, 5, 10 and 15 wt% water loadings at 40, 60 and 80C° and N<sub>2sub> O at (0.08-0.09 mol CO<sub>2sub> /mol alkalinity) at 5 wt% water at 40, 60 and 80C°. CO<sub>2sub> flux was found to be non-linear with respect to log mean pressure driving force (LMPD). Liquid-film mass transfer coefficients (k'g) were calculated by subtracting the gas film resistance (determined from a correlation from literature) from the overall mass transfer measurement. The resulting k'g values for CO<sub>2sub> and N<sub>2sub> O in GAP-1/TEG mixtures were found to be higher than that of 5M aqueous monoethanolamine under comparable driving force albeit at higher solvent viscosities. The k'g values for CO<sub>2sub> were also found to decrease with increasing solvent water content and increase with a decrease in temperature. These observations indicate that mass transfer of CO<sub>2sub> in GAP-1/TEG is linked to the physical solubility of CO<sub>2sub> , which is higher in organic solvents compared to water. This paper expands on the understanding of the unique mass transfer behavior and kinetics of CO<sub>2sub> capture in water-lean solvents.

  7. Torque measurements on single-crystalline Y sub 2 Co sub 17 , Gd sub 2 Co sub 17 and Y sub 2 Fe sub 17

    Energy Technology Data Exchange (ETDEWEB)

    Matthaei, B.; Franse, J.J.M.; Sinnema, S. (Amsterdam Univ. (NL). Natuurkundig Lab.); Radwanski, R.J. (University of Mining and Metallurgy, Krakow (PL). Solid State Physics Dept.)

    1988-12-01

    Contributions from the 3d sublattice to the magnetic anisotropy of the rare-earth transition metal intermetallic compounds have been studied in the Y{sub 2}Co{sub 17}, Gd{sub 2}Co{sub 17} and Y{sub 2}Fe{sub 17}. Values for the anisotropy constants of Gd{sub 2}Co{sub 17} deduced from magnetic torque measurements, perfectly account for the transition in the magnetisation process observed along the hexagonal axis at 1.06 T at liquid-helium temperature.

  8. Exchange-bias effect at La<sub>0.75sub>Sr>0.25sub>MnO>3sub>/LaNiO>3sub> interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Sánchez, J. C. [Centro Atomico Bariloche-CNEA, Rio Negro (Argentina); National Scientific and Technical Research Council, Buenos Aires (Argentina); Nelson-Cheeseman, B. [Univ. of California, Berkeley, CA (United States); Granada, M. [Centro Atomico Bariloche-CNEA, Rio Negro (Argentina); National Scientific and Technical Research Council, Buenos Aires (Argentina); Arenholz, E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Steren, L. B. [National Scientific and Technical Research Council, Buenos Aires (Argentina); Centro Atomico Constituyentes-CNEA, San Martin (Argentina)

    2012-03-26

    In this paper, we show that ferromagnetic/paramagnetic La<sub>0.75sub>Sr>0.25sub>MnO>3sub>/LaNiO>3sub> multilayers present an unexpected magnetic exchange-bias effect (EBE), observed in field-cooled magnetization loops. The exchange-bias field and the enhancement of the coercivity vanish around 50 K. We demonstrate that the oxidation state of the Ni and Mn cations changes from Mn3+-Ni3+ to Mn4+-Ni2+ in the layers close to the interface probed by x-ray absorption spectroscopy measurements. The variation of the valence states is accompanied by a change in the magnetic behavior of the cations at the La<sub>0.75sub>Sr>0.25sub>MnO>3sub>/LaNiO>3sub> interface, possibly giving rise to the formation of magnetic or magnetically frustrated regions that may pin the ferromagnetic a<sub>0.75sub>Sr>0.25sub>MnO>3sub> layers and explain the EBE.

  9. The Nature of the Distinctive Microscopic Features in R<sub>5sub>(SixGe>1-xsub>)>4sub> Magnetic Refrigeration Materials

    Energy Technology Data Exchange (ETDEWEB)

    Ugurlu, Ozan [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Magnetic refrigeration is a promising technology that offers a potential for high energy efficiency. The giant magnetocaloric effect of the R<sub>5sub>(Six>, Ge<sub>1-xsub>)>4sub> alloys (where R=rare-earth and O ≤ x ≤ 1), which was discovered in 1997, make them perfect candidates for magnetic refrigeration applications. In this study the microstructures of Gd<sub>5sub>(Six>, Ge<sub>1-xsub>)>4sub> alloys have been characterized using electron microscopy techniques, with the focus being on distinctive linear features first examined in 1999. These linear features have been observed in R<sub>5sub>(Six>, Ge<sub>1-xsub>)>4sub> alloys prepared from different rare-earths (Gd, Tb, Dy and Er) with different crystal structures (Gd<sub>5sub>Si>4sub>-type orthorhombic, monoclinic and Gd<sub>5sub>Ge>4sub>-type orthorhombic). Systematic scanning electron microscope studies revealed that these linear features are actually thin-plates, which grow along specific directions in the matrix material. The crystal structure of the thin-plates has been determined as hexagonal with lattice parameters a=b=8.53 Å and c=6.40 Å using selected area diffraction (SAD). Energy dispersive spectroscopy analysis, carried out in both scanning and transmission electron microscopes, showed that the features have a composition approximating to R<sub>5sub>Six,Ge>1-xsub>)>3sub>.phase. Orientation relationship between the matrix and the thin-plates has been calculated as [- 1010](1-211)<sub>p>//[010](10-2)<sub>m>. The growth direction of the thin plates are calculated as (22 0 19) and (-22 0 19) by applying the Ag approach of Zhang and Purdy to the SAD patterns of this system. High Resolution TEM images of the Gd<sub>5sub>Ge>4sub> were used to study the crystallographic relationship. A terrace-ledge structure was observed at the interface and a 7° rotation of the reciprocal lattices

  10. Magnetic properties of quadruple perovskite solid solutions Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} and Y{sub 1–y}Ce{sub x}Cu{sub 3}Fe{sub 4}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Makoto; Mori, Shigeo [Department of Materials Science and Engineering, Osaka Prefecture University, Osaka 599-8531 (Japan); Yamada, Ikuya, E-mail: i-yamada@21c.osakafu-u.ac.jp [Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, Osaka 599-8570 (Japan)

    2016-08-26

    Magnetic properties of the quadruple perovskite solid solutions Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} and Y{sub 1–y}Ce{sub y}Cu{sub 3}Fe{sub 4}O{sub 12} are investigated. Ca{sub 1–x}Y{sub x}Cu{sub 3}Fe{sub 4}O{sub 12} shows continuous increase in the ferromagnetic transition temperature as x increases. Y{sub 1–y}Ce{sub y}Cu{sub 3}Fe{sub 4}O{sub 12} exhibits a ferromagnetic-antiferromagnetic transition in the vicinity of y = 0.5. These observations demonstrate the electron doping effect on magnetic properties of charge-disproportionated ACu{sub 3}Fe{sub 4}O{sub 12} phases.

  11. Effect of Plasma Treatment on Multi-Walled Carbon Nanotubes for the Detection of H<sub>2sub>S and SO<sub>2sub>

    Directory of Open Access Journals (Sweden)

    Xiaoxing Zhang

    2012-07-01

    Full Text Available H<sub>2sub>S and SO<sub>2sub> are important characteristic gases of partial discharge (PD generated by latent insulated defects in gas insulated switchgear (GIS. The detection of H<sub>2sub>S and SO<sub>2sub> is of great significance in the diagnosis and assessment of the operating status of GIS. In this paper, we perform experiments on the gas sensitivity of unmodified multi-walled carbon nanotubes (MWNTs and those modified by atmospheric pressure dielectric barrier discharge (DBD air plasma at different times (30, 60 and 120 s for H<sub>2sub>S and SO<sub>2sub>, respectively. The results show that the sensitivity and response time of modified MWNTs to H<sub>2sub>S are both improved, whereas the opposite effects are observed for SO<sub>2sub>. The modified MWNTs have almost zero sensitivity to SO<sub>2sub>. Thus, the MWNTs modified by atmospheric pressure DBD air plasma present good selectivity to H<sub>2sub>S, and have great potential in H<sub>2sub>S detection.

  12. Phase relations in the ZrO{sub 2}-Sm{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system. Experimental investigation and thermodynamic modelling

    Energy Technology Data Exchange (ETDEWEB)

    Fabrichnaya, Olga; Savinykh, Galina; Zienert, Tilo; Schreiber, Gerhard [Technical Univ. of Freiberg (Germany). Inst. of Materials Science; Seifert, Hans J. [Technical Univ. of Freiberg (Germany). Inst. of Materials Science; Karlsruhe Institute of Technology (Germany). Inst. of Applied Physics

    2012-12-15

    Sub-solidus phase relations in the ZrO{sub 2}-Sm{sub 2}O{sub 3}-Y{sub 2}O{sub 3} and Sm{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-Y{sub 2}O{sub 3} systems were experimentally studied at 1523-1873K and thermodynamic databases for these systems were developed. Analysis of phase equilibria in the Sm{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system indicated that REAM phase (Sm,Y){sub 4}Al{sub 2}O{sub 9} is not stable in the Sm{sub 2}O{sub 3} rich-composition. Therefore, the stability limit of the Sm{sub 4}Al{sub 2}O{sub 9} phase was established experimentally and thermodynamic parameters of the Sm{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system were re-optimised. The eutectic melting in the Sm{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system was investigated using differential thermal analysis and scanning electron microscopy. The results obtained were used to assess the mixing parameter of the liquid phase. A new description of binary system was introduced into the database of the ZrO{sub 2}-Sm{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system and phase diagrams were re-calculated. The obtained thermodynamic databases were combined with literature data for the ZrO{sub 2}-Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system and a thermodynamic database for the ZrO{sub 2}-Sm{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system was developed. (orig.)

  13. Unveiling the Structural Evolution of Ag<sub>1.2sub>Mn>8sub>O>16sub> under Coulombically Controlled (De)Lithiation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jianping [Department; Hu, Xiaobing [Energy; Brady, Alexander B. [Department; Wu, Lijun [Energy; Zhu, Yimei [Energy; Takeuchi, Esther S. [Department; Energy; Department; Marschilok, Amy C. [Department; Department; Takeuchi, Kenneth J. [Department; Department

    2018-01-02

    MnO<sub>2sub> materials are considered promising cathode materials for rechargeable lithium, sodium, and magnesium batteries due to their earth abundance and environmental friendliness. One polymorph of MnO<sub>2sub>, α-MnO<sub>2sub>, has 2 × 2 tunnels (4.6 Å × 4.6 Å) in its structural framework, which provide facile diffusion pathways for guest ions. In this work, a silver-ion-containing α-MnO<sub>2sub> (Ag<sub>1.2sub>Mn>8sub>O>16sub>) is examined as a candidate cathode material for Li based batteries. Electrochemical stability of Ag<sub>1.2sub>Mn>8sub>O>16sub> is investigated through Coulombically controlled reduction under 2 or 4 molar electron equivalents (e.e.). Terminal discharge voltage remains almost constant under 2 e.e. of cycling, whereas it continuously decreases under repetitive reduction by 4 e.e. Thus, detailed structural analyses were utilized to investigate the structural evolution upon lithiation. Significant increases in lattice a (17.7%) and atomic distances (~4.8%) are observed when x in Li<sub>xAg>1.2sub>Mn>8sub>O>16sub> is >4. Ag metal forms at this level of lithiation concomitant with a large structural distortion to the Mn–O framework. In contrast, lattice a only expands by 2.2% and Mn–O/Mn-Mn distances show minor changes (~1.4%) at x < 2. The structural deformation (tunnel breakage) at x > 4 inhibits the recovery of the original structure, leading to poor cycle stability at high lithiation levels. This report establishes the correlation among local structure changes, amorphization processes, formation of Ag0, and long-term cycle stability for this silver-containing α-MnO<sub>2sub> type material at both low and high lithiation levels.

  14. On the output factor measurements of the CyberKnife iris collimator small fields: Experimental determination of the k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} correction factors for microchamber and diode detectors

    Energy Technology Data Exchange (ETDEWEB)

    Pantelis, E.; Moutsatsos, A.; Zourari, K.; Petrokokkinos, L.; Sakelliou, L.; Kilby, W.; Antypas, C.; Papagiannis, P.; Karaiskos, P.; Georgiou, E.; Seimenis, I. [Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece) and CyberKnife Center, Iatropolis-MagnitikiTomografia, 54-56 Ethnikis-Antistaseos, 152 31 Athens (Greece); Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 115 27 Athen (Greece); Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece); Accuray Incorporated, Sunnyvale, California 94089 (United States); 1st Department of Radiology, Aretaieion Hospital, Medical School, University of Athens, Vas. Sophias, 115 28 Athens (Greece) and CyberKnife Center, Iatropolis-MagnitikiTomografia, 54-56 Ethnikis-Antistaseos, 152 31 Athens (Greece); Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece); Medical Physics Laboratory, Medical School, Democritus University of Thrace, 2nd Building of Preclinical Section, University Campus, 68100 Alexandroupolis (Greece)

    2012-08-15

    Purpose: To measure the output factors (OFs) of the small fields formed by the variable aperture collimator system (iris) of a CyberKnife (CK) robotic radiosurgery system, and determine the k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} correction factors for a microchamber and four diode detectors. Methods: OF measurements were performed using a PTW PinPoint 31014 microchamber, four diode detectors (PTW-60017, -60012, -60008, and the SunNuclear EDGE detector), TLD-100 microcubes, alanine dosimeters, EBT films, and polymer gels for the 5 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm iris collimators at 650 mm, 800 mm, and 1000 mm source to detector distance (SDD). The alanine OF measurements were corrected for volume averaging effects using the 3D dose distributions registered in polymer gel dosimeters. k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} correction factors for the PinPoint microchamber and the diode dosimeters were calculated through comparison against corresponding polymer gel, EBT, alanine, and TLD results. Results: Experimental OF results are presented for the array of dosimetric systems used. The PinPoint microchamber was found to underestimate small field OFs, and a k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} correction factor ranging from 1.127 {+-} 0.022 (for the 5 mm iris collimator) to 1.004 {+-} 0.010 (for the 15 mm iris collimator) was determined at the reference SDD of 800 mm. The PinPoint k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} correction factor was also found to increase with decreasing SDD; k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} values equal to 1.220 {+-} 0.028 and 1.077 {+-} 0

  15. Magnetic properties of (SrFe{sub 12}O{sub 19}){sub x}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 1–x} composites

    Energy Technology Data Exchange (ETDEWEB)

    Eremina, R. M., E-mail: REremina@yandex.ru; Sharipov, K. R.; Yatsyk, I. V.; Lyadov, N. M. [Zavoisky Physical-Technical Institute (Russian Federation); Gilmutdinov, I. F.; Kiiamov, A. G. [Kazan Federal University (Russian Federation); Kabirov, Yu. V.; Gavrilyachenko, V. G. [Southern Federal University (Russian Federation); Chupakhina, T. I. [Russian Academy of Sciences, Institute of Solid State Chemistry, Ural Branch (Russian Federation)

    2016-07-15

    New composite materials (SrFe{sub 12}O{sub 19}){sub x}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 1–x} (x = 0, 0.05, 1) have been synthesized. Their magnetic properties are studied in the temperature range 5–300 K using the magnetic resonance and magnetometry methods. It is found that strontium hexaferrite microinclusions in the (SrFe{sub 12}O{sub 19}){sub 0.05}(CaCu{sub 3}Ti{sub 4}O{sub 12}){sub 0.95} composite “magnetize” CaCu{sub 3}Ti{sub 4}O{sub 12} at temperatures from 300 to 200 K, forming a ferrimagnetic particle near the SrFe{sub 12}O{sub 19} “core.” The magnetic resonance line below 200 K splits into two lines corresponding to SrFe{sub 12}O{sub 19} and CaCu{sub 3}Ti{sub 4}O{sub 12}. The core effect decoration is manifested in the increase in the Curie–Weiss temperature from 25 K in CaCu{sub 3}Ti{sub 4}O{sub 12} without the doping ceramics to 80 K in the composite with 5% of SrFe{sub 12}O{sub 19}.

  16. Development and Validation of Accident Models for U<sub>3sub>Si>2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, Kyle Allan Lawrence [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hales, Jason Dean [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-07-01

    The purpose of this milestone report is to present the work completed in regards to material model development for U<sub>3sub>Si>2sub> fuel and highlight the results of applying these models to Reactivity Initiated Accidents (RIA), Loss of Coolant Accidents (LOCA), and Station Blackouts (SBO). With the limited experimental data available (essentially only the data used to create the models) true validation is not possible. In the absence of another alternative, code-to-code comparisons have been completed. Qualitative comparisons during postulated accident scenarios between U<sub>3sub>Si>2sub> and UO<sub>2sub> fueled rods have also been completed demonstrating the superior performance of U<sub>3sub>Si>2sub>.

  17. Localized excitons in In sub x Ga sub 1 sub - sub x N/GaN quantum well structure

    CERN Document Server

    Ryu, M Y; Park, S W; Yu, P W; Oh, E S; Park, Y J; Park, H S; Kim, T I

    1998-01-01

    Photoluminescence (PL) photoreflectance (PR) have been employed to study the optical transitions of In sub x Ga sub 1 sub - sub x N/GaN quantum well (QW) structures grown by metal-organic chemical vapor deposition (MOCVD). The main Pl peak at 2.895 eV is attributed to the excitons localized at trap centers, which originate from the In-rich region within the well. Several emission bands on both sides of the main peak are attributed to the interference fringe effects and the recombination of excitons localized at several levels in the In sub 0 sub . sub 1 sub 8 sub 3 Ga sub 0 sub . sub 8 sub 1 sub 7 N well. The PL peak at 3.040 eV is ascribed to the lowest n=1 quantized transition which agrees well the calculated result.

  18. Microscopic theory of magnetization processes in Y (Co sub 1 sub - sub x Al sub x) sub 2

    CERN Document Server

    Khmelevskyi, S; Mohn, P

    2002-01-01

    Employing ab initio electronic structure calculations we study the development of the magnetic properties in Y (Co sub 1 sub - sub x Al sub x) sub 2 for varying Al concentration. The effect of substitutional disorder is treated in the coherent-potential approximation implemented within a tight-binding linear muffin-tin orbital method. The experimentally observed reduction of the critical field of the itinerant electron metamagnetic phase transition with increasing content of non-magnetic Al is explained. It is shown, on the basis of a T = 0 K Stoner type itinerant magnetism theory, that the alloying-induced changes in the shape of the calculated density of states, caused by the Al substitution, lead to (i) a stabilization of the magnetic state, (ii) a smoothening of the first-order metamagnetic transition and (iii) a subsequent suppression of the metamagnetic transition around x 0.15. Analysing the magnetization processes in Y (Co sub 1 sub - sub x Al sub x) sub 2 by varying the strength of the exchange inter...

  19. Modeling char conversion under suspension fired conditions in O{sub 2}/N{sub 2} and O{sub 2}/CO{sub 2} atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Jacob Brix; Peter Arendt Jensen; Anker Degn Jensen [Department of Chemical and Biochemical Engineering, Lyngby (Denmark)

    2011-06-15

    The aim of this investigation has been to model combustion under suspension fired conditions in O{sub 2}/N{sub 2} and O{sub 2}/CO{sub 2} mixtures. Experiments used for model validation have been carried out in an electrically heated Entrained Flow Reactor (EFR) at temperatures between 1173 K and 1673 K with inlet O{sub 2} concentrations between 5 and 28 vol.%. The Coal Combustion Model, COCOMO, includes the three char morphologies: cenospheric char, network char and dense char each divided between six discrete particle sizes. Both combustion and gasification with CO{sub 2} are accounted for and reaction rates include thermal char deactivation, which was found to be important for combustion at high reactor temperatures and high O{sub 2} concentrations. COCOMO show in general good agreement with experimental char conversion profiles at conditions covering zone I-III. From the experimental profiles no effect of CO{sub 2} gasification on char conversion has been found. COCOMO does however suggest that CO{sub 2} gasification in oxy-fuel combustion at low O{sub 2} concentrations can account for as much as 70% of the overall char consumption rate during combustion in zone III. 54 refs., 20 figs., 4 tabs., 2 apps.

  20. Crystallographic orientations and electrical properties of Bi sub 3 sub . sub 4 sub 7 La sub 0. sub 8 sub 5 Ti sub 3 O sub 1 sub 2 thin films on Pt/Ti/SiO sub 2 /Si and Pt/SiO sub 2 /Si substrates

    CERN Document Server

    Ryu, S O; Lee, W J

    2003-01-01

    We report on the crystallization and electrical properties of Bi sub 3 sub . sub 4 sub 7 La sub 0 sub . sub 8 sub 5 Ti sub 3 O sub 1 sub 2 (BLT) thin films for possible ferroelectric non-volatile memory applications. The film properties were found to be strongly dependent on process conditions especially on the intermediate heat treatment conditions. The crystallographic orientation of the films showed sharp changes at the intermediate rapid thermal annealing (RTA) temperature of 450degC. Below 450degC, BLT thin films have (117) orientation while they have preffered c-axis orientation above 450degC. We found that RTA conditions of the first coating layer play a major role in determining the entire crystallographic orientation of the films. The films also showed of ferroelectric hysterisis behavior strongly dependent on RTA treatment. In fact, the remanent polarization of Bi sub 3 sub . sub 4 sub 6 sub 5 La sub 0 sub . sub 8 sub 5 Ti sub 3 O sub 1 sub 2 thin films having (001) preferred crystallographic orient...

  1. The orientational glass (KI) sub 0 sub . sub 5 sub 6 (NH sub 4 I) sub 0 sub . sub 4 sub 4 studied by sup 1 sup 2 sup 7 I nuclear magnetic resonance

    CERN Document Server

    Hinze, G; Zalar, B; Blinc, R

    1997-01-01

    Single crystals of the orientational glass (KI) sub 0 sub . sub 5 sub 6 (NH sub 4 I) sub 0 sub . sub 4 sub 4 have been studied using iodine NMR for temperatures 1.8 K < T < 300 K. Two-dimensional spectroscopy has shown that the quadrupole-perturbed central transitions are predominantly inhomogeneously broadened. The orientational glass transition is already accompanied by a considerable increase of that broadening in the regime of fast motion. Evidence for a random-field smearing of the random-bond-induced freezing process is obtained. Measurements of the spin - lattice relaxation time reveal the existence of a broad distribution of orientational correlation times at low temperatures. (author)

  2. Chemical shift anisotropies of 1H in H<sub>2sub>O(s), H<sub>2sub>S(s), and C<sub>6sub>H>6sub>(s)

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, Larry Michael [Iowa State Univ., Ames, IA (United States)

    1977-10-01

    The proton NMR in powdered samples of H<sub>2sub>O(s), H<sub>2sub>S(s), and C<sub>6sub>H>6sub>(s) have been studied by multiple pulse line narrowing techniques. The resultant spectra provide nuclear magnetic shielding tensors that are (at least approximately) axially symmetric. The anisotropy is 34.2 ± 1.0 ppM for ice, 11.1 ± 1.0 ppM for the highest-temperature phase of solid hydrogen sulfide, and -5.3 ± 0.3 for benzene. Comparisons are made with previous experimental and theoretical work.

  3. Low field magnetoresistance effects in fine particles of La sub 0 sub . sub 6 sub 7 Ca sub 0 sub . sub 3 sub 3 MnO sub 3 perovskites

    CERN Document Server

    Rivas, J; Fondado, A; Rivadulla, F; López-Quintela, M A

    2000-01-01

    In this work magnetic and magnetotransport experimental data in well-characterized small particles of La sub 0 sub . sub 6 sub 7 Ca sub 0 sub . sub 3 sub 3 MnO sub 3 are presented. Grain size reduction leads to a larger resistivity and a decrease in metal-insulator transition temperature. Intrinsic colossal magnetoresistance (CMR) is destroyed while intergranular one is promoted to larger values. This low field MR can be explained taking into account magnetization data through spin-polarized tunneling model, which ensures an acceptable first-order fit between both magnitudes. Finally, low-temperature resistivity upturn present in small particle size samples can be understood in terms of an electrostatic barrier between grains.

  4. Pressure-induced isomerization of a heterometallic rhodium-gold cluster compound: (Rh sub 2 (. mu. -Cl) sub 2 (CNC sub 8 H sub 9 ) sub 4 (. mu. -AuPPh sub 3 )) sub 2 (PF sub 6 ) sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Bray, K.L.; Drickamer, H.G.; Shapley, J.R. (Univ. of Illinois, Urbana (United States)); Mingos, D.M.P.; Watson, M.J. (Univ. of Oxford (England))

    1991-02-20

    Mingos et al. have prepared two isomers of the cluster compound (Rh{sub 2}(mu-Cl{sub 2})(CNC{sub 8}H{sub 9}){sub 4}(mu-AuPPh{sub 3})){sub 2}(PF{sub 6}){sub 2} and have characterized these isomers using single crystal x-ray techniques. The volumes per cluster cation were found to be very similar for both isomers, 1,430 and 1,413 angstroms, and the Rh-Rh bond lengths were found to be 3.262 and 3.008 angstroms for the same isomer. The cluster skeletal geometries were found to differ only at an interior link, and applied pressure appeared to induce a conformational transition around this bond.

  5. SUB-SAHARAN AFRICA

    African Journals Online (AJOL)

    (Meade and l'iot, 1993). Such findings which were carried out at different settings of develop' ing countries including Sub-Saharan Africa, appear conflicting and need to be reconciled through a sub-regional survey. Touching on the preventive mechanisms, especially the use of condoms, the educated are more likely to ...

  6. Sub-structure

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2010-04-01

    Full Text Available Sub-structure generally refers to those components of the building that are constructed below ground, although there are circumstances when sub-structure can also include components above ground such as supporting columns on steeply sloping ground...

  7. Bi sub 2 Sr sub 2 Ca sub n sub - sub 1 Cu sub n O sub y films sputtered on substrates of Bi sub 2 Sr sub 2 CuO sub y single crystals

    CERN Document Server

    Katsurahara, K; Matsumoto, K; Fujiwara, N; Tanaka, H; Kishida, S

    2003-01-01

    We prepared Bi sub 2 Sr sub 2 CaCu sub 2 O sub y (Bi-2212) films on substrates of Bi sub 2 Sr sub 2 CuO sub y (Bi-2201) single crystals by a rf magnetron sputtering method, where He and O sub 2 mixture sputtering gas and an off-axis geometry were used. The EPMA measurement indicated that the films deposited on the Bi-2201 single crystal had approximately the same composition as those on MgO substrate, which showed a Bi-221 single-phase. The film deposited on the Bi-2201 single crystal post-annealed at 500degC for 0.5h showed a metallic temperature dependent resistance in the normal state and the superconducting transition (T sub c sup o sup n sup s sup e sup t) of about 80 K. Therefore, the Bi-2212 films are considerate to grow on the substrate of the Bi-2201 singe crystal. (author)

  8. Local Structural Investigations, Defect Formation, and Ionic Conductivity of the Lithium Ionic Conductor Li <sub>4sub> P <sub>2sub> S <sub>6sub>

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Christian; Sadowski, Marcel; Sicolo, Sabrina; Weber, Dominik A.; Sedlmaier, Stefan J.; Weldert, Kai S.; Indris, Sylvio; Albe, Karsten; Janek, Jurgen; Zeier, Wolfgang G. (JLU); (TU Darmstadt); (Karlsruher)

    2016-12-13

    Glassy, glass–ceramic, and crystalline lithium thiophosphates have attracted interest in their use as solid electrolytes in all-solid-state batteries. Despite similar structural motifs, including PS<sub>4sub>3–, P<sub>2sub>S>6sub>4–, and P<sub>2sub>S>7sub>4– polyhedra, these materials exhibit a wide range of possible compositions, crystal structures, and ionic conductivities. Here, we present a combined approach of Bragg diffraction, pair distribution function analysis, Raman spectroscopy, and 31P magic angle spinning nuclear magnetic resonance spectroscopy to study the underlying crystal structure of Li<sub>4sub>P>2sub>S>6sub>. In this work, we show that the material crystallizes in a planar structural arrangement as a glass ceramic composite, explaining the observed relatively low ionic conductivity, depending on the fraction of glass content. Calculations based on density functional theory provide an understanding of occurring diffusion pathways and ionic conductivity of this Li+ ionic conductor.

  9. The thermal conductivity of mixed fuel U<sub>xPu>1-xsub>O>2sub>: molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiang-Yang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cooper, Michael William Donald [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Christopher Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-16

    Mixed oxides (MOX), in the context of nuclear fuels, are a mixture of the oxides of heavy actinide elements such as uranium, plutonium and thorium. The interest in the UO<sub>2sub>-PuO>2sub> system arises from the fact that these oxides are used both in fast breeder reactors (FBRs) as well as in pressurized water reactors (PWRs). The thermal conductivity of UO<sub>2sub> fuel is an important material property that affects fuel performance since it is the key parameter determining the temperature distribution in the fuel, thus governing, e.g., dimensional changes due to thermal expansion, fission gas release rates, etc. For this reason it is important to understand the thermal conductivity of MOX fuel and how it differs from UO<sub>2sub>. Here, molecular dynamics (MD) simulations are carried out to determine quantitatively, the effect of mixing on the thermal conductivity of U<sub>xPu>1-xsub>O>2sub>, as a function of PuO<sub>2sub> concentrations, for a range of temperatures, 300 – 1500 K. The results will be used to develop enhanced continuum thermal conductivity models for MARMOT and BISON by INL. These models express the thermal conductivity as a function of microstructure state-variables, thus enabling thermal conductivity models with closer connection to the physical state of the fuel.

  10. Hydrothermal synthesis and crystal structures of Na{sub 2}Be{sub 3}(SeO{sub 3}){sub 4}.H{sub 2}O and Cs{sub 2}[Mg(H{sub 2}O){sub 6}]{sub 3}(SeO{sub 3}){sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Chen; Mei, Dajiang; Sun, Chuanling; Liu, Yunsheng; Wu, Yuandong [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science (China)

    2017-09-04

    The selenites, Na{sub 2}Be{sub 3}(SeO{sub 3}){sub 4}.H{sub 2}O and Cs{sub 2}[Mg(H{sub 2}O){sub 6}]{sub 3}(SeO{sub 3}){sub 4}, were synthesized under hydrothermal conditions. The crystal structures of Na{sub 2}Be{sub 3}(SeO{sub 3}){sub 4}.H{sub 2}O and Cs{sub 2}[Mg(H{sub 2}O){sub 6}]{sub 3}(SeO{sub 3}){sub 4} were determined by single-crystal X-ray diffractions. Na{sub 2}Be{sub 3}(SeO{sub 3}){sub 4}.H{sub 2}O crystallizes in the triclinic space group P1 (no. 2) with unit cell parameters a = 4.8493(9), b = 12.013(2), c = 12.077(2) Aa, and Z = 2, whereas Cs{sub 2}[Mg(H{sub 2}O){sub 6}]{sub 3}(SeO{sub 3}){sub 4} crystallizes in the monoclinic space group C2/m (no. 12) with lattice cell parameters a = 12.596(6), b = 7.297(4), c = 16.914(8) Aa, and Z = 2. Na{sub 2}Be{sub 3}(SeO{sub 3}){sub 4}.H{sub 2}O features a three-dimensional open framework structure formed by BeO{sub 4} tetrahedra and SeO{sub 3} trigonal pyramids. Na cations and H{sub 2}O molecules are located in different tunnels. Cs{sub 2}[Mg(H{sub 2}O){sub 6}]{sub 3}(SeO{sub 3}){sub 4} has a structure composed of isolated [Mg(H{sub 2}O){sub 6}] octahedra and SeO{sub 3} trigonal pyramids interacted by hydrogen bonds, and Cs cations are resided in-between. Both compounds were characterized by thermogravimetric analysis and FT-IR spectroscopy. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Field-induced non-collinear magnetic structures in Er sub 2 Fe sub 14 B-based compounds. [Er sub 2 (Fe sub 1-x Ga sub x ) sub 14 B; Er sub 2 (Fe sub 1-x Si sub x ) sub 14 B; Er sub 2 (Fe sub 1-x Co sub x ) sub 14 B

    Energy Technology Data Exchange (ETDEWEB)

    Radwanski, R.J.; Boer, F.R. de (Van der Waals-Zeeman Lab., Univ. van Amsterdam (Netherlands)); Zhong, X.P. (Van der Waals-Zeeman Lab., Univ. van Amsterdam (Netherlands) Magnetism Lab., Inst. of Physics, Academia Sinica, Beijing (China)); Yang, F.M.; Li, J.Y. (Magnetism Lab., Inst. of Physics, Academia Sinica, Beijing (China)); Kohashi, T.; Ono, M.; Date, M. (Dept. of Physics, Osaka Univ. (Japan)); Yamagishi, A. (Research Center for Extreme Materials, Osaka Univ. (Japan))

    1992-02-01

    Magnetic isotherms have been measured at 4.2 K on magnetically aligned polycrystalline Er{sub 2}(Fe,X){sub 14}B compounds with X=Ga, Si or Co. A field-induced transition of the First-Order Moment-Reorientation (FOMR) type with the formation of a non-collinear magnetic structure of the 3d and 4f sublattices has been observed. The transition-field value, 42 T for Er{sub 2}Fe{sub 14}B, decreases significantly with increasing concentration of the substitutions. An exchange field of 219 T for Er{sub 2}Fe{sub 14}B has been derived. (orig.).

  12. Growth of single phase Bi sub 2 Sr sub 2 CaCu sub 2 O sub x whiskers using optimized starting compositions for glassy precursors

    CERN Document Server

    Sugimata, E; Kume, E; Sakai, S

    2003-01-01

    Single phase Bi sub 2 Sr sub 2 CaCu sub 2 O sub x whiskers were grown by optimized starting compositions for glassy precursors. The most optimal starting composition ratio and the composition after the whisker growth were found to be Bi : Sr : Ca : Al = 0.96 : 1.10 : 0.37 : 1.21 : 0.61 and Bi sub 2 sub . sub 2 sub 5 Sr sub 2 sub . sub 0 sub 9 Ca sub 0 sub . sub 8 sub 7 Cu sub 2 sub . sub 0 sub 0 O sub x , respectively. From the results of R-T characteristics, it was determined that there was no intergrowth of the Bi sub 2 Sr sub 2 Ca sub 2 Cu sub 3 O sub x phase. (author)

  13. Catalytic N <sub>2sub> Reduction to Silylamines and Thermodynamics of N <sub>2sub> Binding at Square Planar Fe

    Energy Technology Data Exchange (ETDEWEB)

    Prokopchuk, Demyan E. [Center; Wiedner, Eric S. [Center; Walter, Eric D. [Environmental Molecular Sciences Laboratory, Richland, Washington 99352, United States; Popescu, Codrina V. [Department; Piro, Nicholas A. [Department; Kassel, W. Scott [Department; Bullock, R. Morris [Center; Mock, Michael T. [Center

    2017-06-27

    The geometric constraints imposed by a tetradentate P<sub>4sub>N>2sub> ligand play an essential role in stabilizing square planar Fe complexes with changes in metal oxidation state. A combination of high-pressure electrochemistry and variable temperature UV-vis spectroscopy were used to obtain these thermodynamic measurements, while X-ray crystallography, 57Fe Mössbauer spectroscopy, and EPR spectroscopy were used to fully characterize these new compounds. Analysis of Fe0, FeI, and FeII complexes reveals that the free energy of N<sub>2sub> binding across three oxidation states spans more than 37 kcal mol-1. The square pyramidal Fe0(N<sub>2sub>)(P>4sub>N>2sub>) complex catalyzes the conversion of N<sub>2sub> to N(SiR<sub>3sub>)>3sub> (R = Me, Et) at room temperature, representing the highest turnover number (TON) of any Fe-based N<sub>2sub> silylation catalyst to date (up to 65 equiv N(SiMe<sub>3sub>)>3sub> per Fe center). Elevated N<sub>2sub> pressures (> 1 atm) have a dramatic effect on catalysis, increasing N<sub>2sub> solubility and the thermodynamic N<sub>2sub> binding affinity at Fe0(N<sub>2sub>)(P>4sub>N>2sub>). Acknowledgment. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences. EPR experiments were performed using EMSL, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the U.S. DOE. Computational resources were provided by the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. The authors thank Prof. Yisong Alex Guo at Carnegie Mellon University for recording Mössbauer data for some complexes and Emma

  14. Lithium insertion in Ba sub 2 YCu sub 3 O sub 7-y

    Energy Technology Data Exchange (ETDEWEB)

    Alario-Franco, M.A.; Moran, E.; Varez, A. (Dept. de Quimica Inorganica 1, Univ. Complutense, Madrid (Spain)); Santamaria, J.; Sanchez-Quesada, F. (Dept. de Fisica Aplicada 3, Univ. Complutense, Madrid (Spain))

    1990-12-01

    Novel materials, Li{sub x}Ba{sub 2}YCu{sub 3}O{sub 7-y}(0{<=}x{<=}2), have been obtained by reaction of Ba{sub 2}YCu{sub 3}O{sub 7-y} with n-butyllithium. The most striking feature of these materials is the coexistence of both ionic conductivity and superconductivity for 0

  15. Crystallographic and magnetic properties of R sub 3 Fe sub 2 sub 9 sub - sub x V sub x N sub 4 (R=Y, Ce, Nd, Sm, Gd, Tb, and Dy)

    CERN Document Server

    Han Xiu Feng; Li Qi; Zhang Mao Cai; Zhou Shou Zeng

    1998-01-01

    A systematic investigation of crystallographic and magnetic properties of nitride R sub 3 Fe sub 2 sub 9 sub - sub x V sub x N sub 4 (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. Nitrogenation leads to a relative volume expansion of about 6%. The lattice constants and unit cell volume decrease with increasing rare-earth atomic number from Nd to Dy, reflecting the lanthanide contraction. On average, the Curie temperature increases due to the nitrogenation to about 200 K compared with its parent compound. Generally speaking, nitrogenation also results in a remarkable improvement of the saturation magnetization and anisotropy fields at 4.2 K and room temperature for R sub 3 Fe sub 2 sub 9 sub - sub x V sub x N sub 4 compared with their parent compounds. The transition temperature indicates the spin reorientations of R sub 3 Fe sub 2 sub 9 sub - sub x V sub x N sub 4 for R Nd and Sm are at around 375 and 370 K which are higher than that of R sub 3 Fe sub 2 sub 9 sub - sub x V sub x for R = Nd and Sm 145...

  16. Polarized luminescence of Y sub 3 Al sub 5 O sub 1 sub 2 -Tb and Y sub 3 Al sub 5 O sub 1 sub 2 -Ho garnets controllable by magnetic field

    CERN Document Server

    Valiev, U V; Sokolov, B Y

    2002-01-01

    One studied spectra of circularly polarized luminescence of Y sub 3 Al sub 5 O sub 1 sub 2 -Tb and Y sub 3 Al sub 5 O sub 1 sub 2 -Ho garnets within sup 5 D sub 4 -> sup 7 F sub 5 -transition wave length range in Tb sup 3 sup + and within sup 5 S sub 2 -> sup 5 I sub 8 -transition wave length range in Ho sup 3 sup + ion. One detected substantial difference in intensity of orthogonal circularly polarized garnets. The obtained results enable to conclude that strong effect of magnetic field on intensity of oscillator of 4f -> 4f-transitions is general phenomenon in rare-earth system with energy spectrum quasi-doublet structure. Contribution of mixing in external magnetic field of Tb sup 3 sup + and Ho sup 3 sup + ion electron states may play essential role in magnetooptics of such systems

  17. Evaluation of the La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} system as SOFC cathode material with 8YSZ and LSGM as electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Aguadero, A.; Escudero, M.J. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid (CSIC),C/Sor Juana Ines de la Cruz 3, Campus Cantoblanco, 28049 Madrid (Spain); Daza, L. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica,(CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2008-05-31

    Materials formulated as La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} (0 {<=} x {<=} 1) have been synthesised to be evaluated as possible cathode materials in SOFCs. Their crystal structures have been investigated by high-resolution neutron powder diffraction at RT so as to map out the phase diagram. The thermal expansion coefficients have been determined to be in the range of 10.8-13.0 x 10{sup -} {sup 6} K{sup -} {sup 1}. Total conductivity values are as good as 87 S cm{sup -} {sup 1} at 580 C for x = 0.4. In order to assess the performance of each oxide as cathode material, ac impedance measurements were carried out on La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}}/electrolyte/La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} symmetrical cells with either LSGM or 8YSZ as electrolyte material. For all the electrode compositions studied, the best specific resistance (ASR) values were obtained with LSGM as electrolyte. The better performance of x = 0.4 and 0.6 (ASR {proportional_to} 1 and ohm; cm{sup 2} at 850 C) compositions has been associated with the magnitude of the total conductivity and the matching of the TEC values of the cathodes with those of the electrolytes. (author)

  18. Thermal properties of (Dy{sub x}Gd{sub 1-x}){sub 3}Ga{sub 5}O{sub 12} garnet single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, T.; Kimura, H.; Maeda, H. [Tsukuba Magnet Labs., Tsukuba (Japan)] [and others

    1997-06-01

    The solid solution (Dy{sub x}Gd{sub 1-x}){sub 3}Ga{sub 5}O{sub 12} garnet is proposed as a high heat capacity material below 2 K for regenerator. A short range order interaction resulting from the magnetic frustration in Gd{sub 3}Ga{sub 5}O{sub 12} gives a considerably high heat capacity below 2 K. At a magnetic field B = {approximately}1 T, Gd{sub 3}Ga{sub 5}O{sub 12} has a sharp anomaly in its specific heat at {approximately}0.37 K related to an antiferromagnetic transition, keeping the large heat capacity. By substituting Gd ion by Dy ion, an anisotropy will be produced in (Dy{sub x}Gd{sub 1-x}){sub 3}Ga{sub 5}O{sub 12} and it enhances the antiferromagnetic long range order interactions. The specific heat measurement for (Dy{sub 0.5}Gd{sub 0.5}){sub 3}Ga{sub 5}O{sub 12} at B = 0 T showed that heat capacity of (Dy{sub 0.5}Gd{sub 0.5}){sub 3}Ga{sub 5}O{sub 12} is comparable largely to that of Gd{sub 3}Ga{sub 5}O{sub 12} and a transition temperature may be found below 0.6 K. From the thermal conductivity measurement, a strong correlation with magnetic field has been found. The reduction in the thermal conductivity caused by the magnetic field is the largest in Dy{sub 3}Ga{sub 5}O{sub 12} and it decreases by increasing the concentration of Gd ion.

  19. Magneto caloric effect in (Dy{sub x}Gd{sub 1-x}){sub 3}Ga{sub 5}O{sub 12} for adiabatic demagnetization refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, Takenori; Kamiya, Koji; Okano, Takahiro; Matsumoto, Koichi

    2003-05-01

    Gadolinium and dysprosium gallium garnet single crystals (Dy{sub x}Gd{sub 1-x}){sub 3}Ga{sub 5}O{sub 12} (x=0,0.5 and 1) have been investigated for adiabatic demagnetization refrigeration used as magnetic materials between 0.5 and 5 K. Specific heat measurement of (Dy{sub 0.5}Gd{sub 0.5}){sub 3}Ga{sub 5}O{sub 12} showed a large and broad peak similar to that of Gd{sub 3}Ga{sub 5}O{sub 12} and it suggests that the geometrical frustration in Gd{sub 3}Ga{sub 5}O{sub 12} still remains in (Dy{sub 0.5}Gd{sub 0.5}){sub 3}Ga{sub 5}O{sub 12}. Magneto caloric effect of (Dy{sub 0.5}Gd{sub 0.5}){sub 3}Ga{sub 5}O{sub 12} was about four times larger than that of Gd{sub 3}Ga{sub 5}O{sub 12} for the magnetic field of 1 T between 0.5 and 5 K. Therefore, the magnetic entropy change of Gd{sub 3}Ga{sub 5}O{sub 12} by the external magnetic fields could be enhanced by substituting Dy{sup 3+} ion for Gd{sup 3+} ion for the magnetic fields of <2 T between 0.5 and 5 K.

  20. XPS analysis of nanocomposite Li{sub 2x−y}Mn{sub 1−x}PS{sub 3}(C{sub 13}H{sub 11}N{sub 2}){sub y} films

    Energy Technology Data Exchange (ETDEWEB)

    Silipigni, L., E-mail: lsilipigni@unime.it [Dipartimento di Fisica e di Scienze della Terra, Università di Messina, V.le F.Stagno d’Alcontres 31, I-98166 Messina (Italy); Schirò, L., E-mail: lschiro@unime.it [Dipartimento di Fisica e di Scienze della Terra, Università di Messina, V.le F.Stagno d’Alcontres 31, I-98166 Messina (Italy); Scolaro, L. Monsù, E-mail: lmonsu@unime.it [Dipartimento di Scienze Chimiche, Università di Messina, Salita Sperone 31, I-98166 Messina (Italy); De Luca, G., E-mail: delucag@unime.it [Dipartimento di Scienze del Farmaco e Prodotti per la Salute, V.le Annunziata, I-98168 Messina (Italy); Salvato, G., E-mail: salvato@me.cnr.it [CNR-IPCF Istituto per i Processi Chimico-Fisici, V.le F. Stagno d’Alcontres 37, I-98158 Messina (Italy)

    2013-09-01

    Intercalation of 9-aminoacridine (9AA: C{sub 13}H{sub 10}N{sub 2}) in thin films of exfoliated Li{sub 2x−y}Mn{sub 1−x}PS{sub 3} has been performed by means of a solution approach starting from the hydrochloride salt of the organic species (9AAHCl: C{sub 13}H{sub 10}N{sub 2}·HCl). The resulting nanocomposite Li{sub 2x−y}Mn{sub 1−x}PS{sub 3}(C{sub 13}H{sub 11}N{sub 2}){sub y} films have been investigated by X-ray photoemission spectroscopy (XPS), at room temperature, in the regions of the Mn, P, S and Cl 2p, Li, C and N 1s and Mn 3p core levels. The XPS analysis has been also carried out on the 9-aminoacridine hydrochloride films whose XPS spectra have been compared with those of the Li{sub 2x−y}Mn{sub 1−x}PS{sub 3}(C{sub 13}H{sub 11}N{sub 2}){sub y} films to obtain information about the nature of the interaction between the guest species (9AAH{sup +}) and the matrix (Li{sub 2x−y}Mn{sub 1−x}PS{sub 3}{sup −}).

  1. Scintillation characteristics of nonstoichiometric phases formed in MF sub 2 -GdF sub 3 -CeF sub 3 systems Part III. Dense Gd sub 1 sub - sub x sub - sub y M sub x Ce sub y F sub 3 sub - sub x tysonite-related crystals (M=Ca, Sr)

    CERN Document Server

    Kobayashi, M; Sobolev, B P; Zhmurova, Z I; Krivandina, E A; Nikl, M

    1999-01-01

    We evaluated the scintillation characteristics and the radiation hardness of Gd sub 1 sub - sub x Ca sub x F sub 3 sub - sub x and Gd sub 1 sub - sub x Sr sub x F sub 3 sub - sub x tysonite-type solid solutions (close to 6.6 g/cm sup 3 in density) doped with Ce which were grown from the congruent melt. As the Ce concentration increased, the Ce sup 3 sup + emission at 345 nm increased to a level comparable with the Gd sup 3 sup + emission at 310 nm. Both emissions, however, were slow with the decay constant in the order of ms. The radiation hardness, which was roughly 10 sup 4 rad, tends to degrade as the wavelength decreases and/or the Ce concentration increases. Both spontaneous recovery and UV annealing of the radiation damages were significant. The intensity of the gamma-ray excited luminescence, integrated over time, was as large as 50% of that in BaF sub 2 (12% of that in CdWO sub 4). When the Ce concentration is nil or only small, the yellow-green luminescence for UV excitation was as intense as in CdWO...

  2. Synthesis and Luminescence Characteristics of Cr3+ doped Y<sub>3sub>Al>5sub>O>12sub> Phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Brenda A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dabestani, Reza T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lewis, Linda A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Thompson, Cyril V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Collins, Case T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Aytug, Tolga [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-10-01

    Luminescence performance of yttrium aluminum garnet (Y<sub>3sub>Al>5sub>O>12sub>) phosphors as a function of Cr3+ concentration has been investigated via two different wet-chemical synthesis techniques, direct- (DP) and hydrothermal-precipitation (HP). Using either of these methods, the red-emitting phosphor [Y<sub>3sub>Al>5-xsub>CrxO>12sub> (YAG: Cr3+)] showed similar photoluminescence (PL) intensities once the dopant concentration was optimized. Specifically, the YAG: Cr3+ PL emission intensity reached a maximum at Cr3+ concentrations of x = 0.02 (0.4 at.%) and x = 0.13 (2.6 at.%) for DP and HP processed samples, respectively. The results indicated the strong influence of the processing method on the optimized YAG: Cr3+ performance, where a more effective energy transfer rate between a pair of Cr3+ activators at low concentration levels was observed by using the DP synthesis technique. Development of a highly efficient phosphor, using a facile synthesis approach, could significantly benefit consumer and industrial applications by improving the operational efficiency of a wide range of practical devices.

  3. Electrical transport and magnetic properties of (Ce sub 1 sub - sub x Gd sub x)Pt sub 2 Si sub 2 (0 <= x <= 1)

    CERN Document Server

    Tchokonte, M B T; Kaczorowski, D

    2003-01-01

    Results of electrical resistivity, magnetization and susceptibility measurements are reported for the pseudo-ternary alloys (Ce sub 1 sub - sub x Gd sub x)Pt sub 2 Si sub 2. The end-members of the alloy series are the non-magnetic Kondo lattice compound CePt sub 2 Si sub 2 and the antiferromagnet GdPt sub 2 Si sub 2. The resistivity results reveal a rapid evolution to Kondo behaviour beyond small Ce substitution in GdPt sub 2 Si sub 2 (for 1 - x >= 0.2). Coherent Kondo scattering is observed for larger Ce substitution (1 - x >= 0.75). The low-temperature resistivity of CePt sub 2 Si sub 2 in the coherent state is dominantly a T sup 2 Fermi-liquid behaviour. The magnetization results suggest metamagnetic behaviour at Gd-rich concentrations. From the susceptibility results, the Gd and Ce moments seem to contribute independently to the magnetism of the alloy samples.

  4. Low-field tunnel-type magnetoresistance properties of polycrystalline and epitaxial La sub 0 sub . sub 6 sub 7 Sr sub 0 sub . sub 3 sub 3 MnO sub 3 thin films

    CERN Document Server

    Shim, I B; Choi, S Y

    2000-01-01

    The low-field tunnel-type magnetoresistance (TMB) properties of sol-gel derived polycrystalline and epitaxial La sub 0 sub . sub 6 sub 7 Sr sub 0 sub . sub 3 sub 3 MnO sub 3 (LSMO) thin films were investigated. The polycrystalline thin films were fabricated on Si (100) with a thermally oxidized SiO sub 2 layer while the epitaxial thin films were grown on LaAlO sub 3 (001) single-crystal substrates. The epitaxial thin films displayed both typical intrinsic colossal magnetoresistance (CMR) and abnormal extrinsic tunnel-type magnetoresistance behaviors. Tunnel-type MR ratio as high as 0.4% were observed in the polycrystalline thin films at a field of 120 Oe at room temperature (300 K) whereas the ratios were less than 0.1% for the epitaxial films in the same field range. The low-field tunnel-type MR of polycrystalline LSMO/SiO sub 2 ?Si (100) thin films originated from the behaviors of the grain-boundary properties.

  5. Giant Magneto-Resistance in Epitaxial (La<sub>0.7sub>Sr>0.3sub>MnO>3sub>)>0.5sub>: (ZnO)<sub>0.5sub> Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wei [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Jiang, Y. X. [Georgia Inst. of Technology, Atlanta, GA (United States); Ihlefeld, Jon [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Ping [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Stephen R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    A great deal of research has been carried out in oxide material systems. Among them, ZnO and La<sub>0.7sub>Sr>0.3sub>MnO>3sub> (LSMO) are of particular interest due to their superb optical properties and colossal magneto-resistive effect. Here, we report our recent results of magneto-transport studies in self-assembled, epitaxial (ZnO)0.5:(La<sub>0.7sub>Sr>0.3sub>MnO>3sub>)>0.5sub> nanocomposite films.

  6. Electronic structures of (Pb sub 2 Cu)Sr sub 2 Eu sub x Ce sub n sub - sub x Cu sub 2 O sub 2 sub n sub + sub 6 (n=2, 3): Effect of fluorite blocks between adjacent CuO sub 2 layers

    CERN Document Server

    Arai, M

    2003-01-01

    The electronic structures of (Pb sub 2 Cu)Sr sub 2 Eu sub x Ce sub n sub - sub x Cu sub 2 O sub 2 sub n sub + sub 6 (n = 2, 3) compounds which have fluorite blocks between two adjacent CuO sub 2 layers have been studied by using ab-initio method. It is found that the anisotropy is enhanced by inserting the fluorite blocks. The Fermi velocity perpendicular to the CuO sub 2 layers decreases as the thickness of fluorite blocks increases. The Eu substitution is found to affect both the atomic positions and electronic structures. The distance between apical oxygen and copper becomes shorter by the Eu substitution. The energy bands derived from oxygens in the fluorite blocks approach Fermi energy as the content of Eu substitution increases. (author)

  7. Novel joining of dissimilar ceramics in the Si<sub>3sub>N>4sub>-Al>2sub>O>3sub> system using polytypoid functional gradients

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Caroline Sunyong [Univ. of California, Berkeley, CA (United States)

    2001-01-01

    A unique approach to crack-free joining of heterogeneous ceramics is demonstrated by the use of sialon polytypoids as Functionally Graded Materials (FGM) as defined by the phase diagram in the system, Si<sub>3sub>N>4sub>-Al>2sub>O>3sub>. Polytypoids in the Al<sub>2sub>O>3sub>-Si>3sub>N>4sub> system offer a path to compatibility for such heterogeneous ceramics. The first part of the dissertation describes successful hot press sintering of multilayered FGM's with 20 layers of thickness 500 mm each. Transmission Electron Microscopy was used to identify the polytypoids at the interfaces of different areas of the joint. It has been found that the 15R polytypoid was formed in the Al<sub>2sub>O>3sub>-contained layers and the 12H polytypoid was formed in the Si<sub>3sub>N>4sub>-contained layers. The second part of the dissertation discusses the mechanical properties of these polytypoidally joined Si<sub>3sub>N>4sub>-Al>2sub>O>3sub>. The thermal stresses of this FGM junction were analyzed using a finite element analysis program (FEAP) taking into account both coefficient of thermal expansion (CTE) and modulus variations. From this analysis, the result showed a dramatic decrease in radial, axial and hoop stresses as the FGM changes from three layers to 20 graded layers. Scaling was considered, showing that the graded transition layer should constitute about 75 percent or more of the total sample thickness to reach a minimal residual stress. Oriented Vickers indentation testing was used to qualitatively characterize the strengths of the joint and the various interfaces. The indentation cracks were minimally or not deflected at the sialon layers, implying strong interfaces. Finally, flexural testing was conducted at room temperature and at high temperature. The average strength at room temperature was found to be 581 MPa and the average strength at high temperature (1200 °C) was found

  8. London penetration depth measurements in Ba (Fe<sub>1-xsub>Tx)>2sub>As>2sub>(T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, Ryan T. [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    The London penetration depth has been measured in various doping levels of single crystals of Ba(Fe<sub>1-xsub>Tx)>2sub>As>2sub> (T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors by utilizing a tunnel diode resonator (TDR) apparatus. All in-plane penetration depth measurements exhibit a power law temperature dependence of the form Δλ<sub>ab>(T) = CTn, indicating the existence of low-temperature, normal state quasiparticles all the way down to the lowest measured temperature, which was typically 500 mK. Several different doping concentrations from the Ba(Fe<sub>1-xsub>Tx)>2sub>As>2sub> (T=Co,Ni) systems have been measured and the doping dependence of the power law exponent, n, is compared to results from measurements of thermal conductivity and specific heat. In addition, a novel method has been developed to allow for the measurement of the zero temperature value of the in-plane penetration depth, λ<sub>ab>(0), by using TDR frequency shifts. By using this technique, the doping dependence of λ<sub>ab>(0) has been measured in the Ba(Fe<sub>1-xsub>Cox)>2sub>As>2sub> series, which has allowed also for the construction of the doping-dependent superfluid phase stiffness, ρ<sub>s>(T) = [λ(0)/λ(T)]2. By studying the effects of disorder on these superconductors using heavy ion irradiation, it has been determined that the observed power law temperature dependence likely arises from pair-breaking impurity scattering contributions, which is consistent with the proposed s±-wave symmetry of the superconducting gap in the dirty scattering limit. This hypothesis is supported by the measurement of an exponential temperature dependence of the penetration depth in the intrinsically clean LiFeAs, indicative of a nodeless superconducting gap.

  9. Electronic phase separation in La sub 1 sub . sub 2 Sr sub 1 sub . sub 8 Mn sub 2 O sub 7 observed by sup 5 sup 5 Mn nuclear magnetic resonance

    CERN Document Server

    Shimizu, K; Renard, J P; Pevcolevschi, A

    2003-01-01

    A single crystal of perovskite bilayer manganite La sub 1 sub . sub 2 Sr sub 1 sub . sub 8 Mn sub 2 O sub 7 has been studied by the sup 5 sup 5 Mn NMR technique. The observed spectra at 4.2 K in zero external magnetic field are broad and spread in the frequency range 310-480 MHz. The shape of the spectrum depends strongly on the rf radiation field for exciting and refocusing a spin-echo signal. In external magnetic fields up to 1.75 T, signals arising from both metallic and insulating phases are observed, which is an evidence of the electronic phase separation. (author)

  10. Water Oxidation Catalysis by Co(II) Impurities in Co(III) <sub>4sub> O <sub>4sub> Cubanes

    Energy Technology Data Exchange (ETDEWEB)

    Ullman, Andrew M.; Liu, Yi; Huynh, Michael; Bediako, D. Kwabena; Wang, Hongsen; Anderson, Bryce L.; Powers, David C.; Breen, John J.; Abruña, Héctor D.; Nocera, Daniel G.

    2014-12-17

    The observed water oxidation activity of the compound class Co<sub>4sub>O>4sub>(OAc)>4sub>(Py–X)>4sub> emanates from a Co(II) impurity. This impurity is oxidized to produce the well-known Co-OEC heterogeneous cobaltate catalyst, which is an active water oxidation catalyst. We present results from electron paramagnetic resonance spectroscopy, nuclear magnetic resonance line broadening analysis, and electrochemical titrations to establish the existence of the Co(II) impurity as the major source of water oxidation activity that has been reported for Co<sub>4sub>O>4sub> molecular cubanes. Differential electrochemical mass spectrometry is used to characterize the fate of glassy carbon at water oxidizing potentials and demonstrate that such electrode materials should be used with caution for the study of water oxidation catalysis.

  11. Correlating Lithium Hydroxyl Accumulation with Capacity Retention in V <sub>2sub> O <sub>5sub> Aerogel Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Wangoh, Linda W.; Huang, Yiqing; Jezorek, Ryan L.; Kehoe, Aoife B.; Watson, Graeme W.; Omenya, Fredrick; Quackenbush, Nicholas F.; Chernova, Natasha A.; Whittingham, M. Stanley; Piper, Louis F. J.

    2016-05-11

    V<sub>2sub>O>5sub> aerogels are capable of reversibly intercalating more than 5 Li+/V<sub>2sub>O>5sub> but suffer from lifetime issues due to their poor capacity retention upon cycling. We employed a range of material characterization and electrochemical techniques along with atomic pair distribution function, X-ray photoelectron spectroscopy, and density functional theory to determine the origin of the capacity fading in V<sub>2sub>O>5sub> aerogel cathodes. In addition to the expected vanadium redox due to intercalation, we observed LiOH species that formed upon discharge and were only partially removed after charging, resulting in an accumulation of electrochemically inactive LiOH over each cycle. Our results indicate that the tightly bound water that is necessary for maintaining the aerogel structure is also inherently responsible for the capacity fade.

  12. High-resolution spectrum of the {nu}{sub 1}+{nu}{sub 4}(E), {nu}{sub 3}+{nu}{sub 4}(E), {nu}{sub 3}+{nu}{sub 4}(A{sub 1}), and {nu}{sub 3}+{nu}{sub 4}(A{sub 2}) bands of the PH{sub 3} molecule: assignments and preliminary analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ulenikov, O.N. E-mail: ulenikov@phys.tsu.ru; Bekhtereva, E.S.; Kozinskaia, V.A.; Zheng Jingjing; He Shenggui; Hu Shuiming; Zhu Qingshi; Leroy, C.; Pluchart, L

    2004-02-01

    The high-resolution (0.005 cm{sup -1}) Fourier transform infrared spectrum of PH{sub 3} is recorded in the region between 3280 and 3580 cm{sup -1} where the following bands are located: {nu}{sub 1}+{nu}{sub 4}(E), {nu}{sub 3}+{nu}{sub 4}(E), {nu}{sub 3}+{nu}{sub 4}(A{sub 1}), forbidden on symmetry band {nu}{sub 3}+{nu}{sub 4}(A{sub 2}), and very weak bands {nu}{sub 1}+{nu}{sub 2}(A{sub 1}), {nu}{sub 2}+{nu}{sub 3}(E). Transitions are assigned to the first four ones. Vibrational analysis of known experimental data is made.

  13. Neutron diffraction studies of Ho sub 2 Fe sub 9 Ga sub 8 sub - sub x Al sub x (x=2, 4) at 50 K and 300 K

    CERN Document Server

    Chen, D F; Sun, K; Ridwan; Mujamilah, A; Marsongkohadi; Yan, Q W; Zhang, P L; Shen, B G; Gong, H Y

    1998-01-01

    The crystallographic and magnetic structures of Ho sub 2 Fe sub 9 Ga sub 8 sub - sub x Al sub x (x=2, 4) were studied by powder neutron diffraction at 50 K and 300 K. The atom fractional occupancies of gallium and aluminium and the magnetic moments of Ho and Fe atoms were obtained by a Rietveld analysis program. The gallium atoms occupy preferentially 18f sites, but aluminium atoms prefer to occupy 6c sites. The magnetic moments of the phase with the x=2, 4 at 50 K and x=2 at 300 K show uniaxial anisotropy. A qualitative explanation for this result is given. (author)

  14. In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructured nanoparticles with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Yonglei [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Yin, Xingtian; He, Zuoli; Liu, Xiaobin; Yang, Yawei; Shao, Jinyou [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Kong, Ling Bing, E-mail: ELBKong@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

    2016-11-30

    Highlights: • Visible-light photocatalytic activities of the nanostructured In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructures were studied. • Effect of In{sub 2}O{sub 3} content on the photocatalytic activity of the In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructure was evaluated. • 0.1In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructure photocatalyst shows a superior photocatalytic activity. • Based on Mott-Schottky analysis and active species detection, a mechanism for the separation of photogenerated carriers is proposed. • The effective separation process of the photogenerated electron-hole pairs was testified by photocurrent test. - Abstract: In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} composite photocatalysts with various contents of cubic In{sub 2}O{sub 3} nanoparticles were fabricated by using impregnation method. A thriving modification of Bi{sub 2}Sn{sub 2}O{sub 7} by an introduction of In{sub 2}O{sub 3} was confirmed by using X-ray diffraction, UV–vis diffuse reflectance spectrometry, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The samples composed of hybrids of In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} exhibited a much higher photocatalytic activity for the degradation of Rhodamine B under visible light, as compared with pure In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} nanoparticles. Optimized composition of the composite photocatalysts was 0.1In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7}, which shows a rate constant higher than those of pure In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} by 4.06 and 3.21 times, respectively. Based on Mott-Schottky analysis and active species detection, the photoexcited electrons in the conduction band of In{sub 2}O{sub 3} and the holes in the valence band of Bi{sub 2}Sn{sub 2}O{sub 7} participated in reduction and oxidation reactions, respectively. Hence, ·OH, ·O{sub 2}{sup −} and h

  15. Size-dependent properties of YBa sub 2 Cu sub 3 O sub 6 sub + sub x nanopowder

    CERN Document Server

    Paturi, P; Huhtinen, H; Huhtala, V P; Laiho, R

    2003-01-01

    YBa sub 2 Cu sub 3 O sub 6 sub + sub x nanopowder, prepared by the citrate sol-gel method, is segregated by sedimentation in ethanol into three size groups with average particle heights of 0.7, 1.6 and 2.3 nm. The structural properties and composition of the powders, investigated by x-ray diffraction, atomic force microscopy, Auger electron spectroscopy and EPR-spectroscopy, show no clear differences, except the size. According to investigations by magnetometry and by non-resonant microwave absorption the as-prepared powder contains weak links which, however, disappear during the segregation. The magnetic susceptibility of the samples decreases with the decreasing particle size, in agreement with the susceptibility values calculated from the London equations for cylindrical particles smaller than the London penetration depth. In all three size groups the critical temperature of superconductivity is 92 K.

  16. Sub specie aeternitatis

    Directory of Open Access Journals (Sweden)

    Laura Gioeni

    2012-10-01

    Full Text Available Per delineare il rapporto tra etica ed estetica nell'architettura e rispondere alla domanda principale «che cosa è o dovrebbe essere un buon architetto?», il saggio discute la tesi di Wittgenstein secondo cui «l'opera d'arte è l'oggetto visto sub specie aeternitatis e la vita buona è il mondo visto sub specie aeternitatis. Questa è la connessione tra arte ed etica».

  17. Transport properties of Na doped La sub 1 sub - sub x Ca sub x sub - sub y Na sub y MnO sub 3 measured in a pulsed magnetic field

    CERN Document Server

    Bhattacharya, S; Pal, S; Chatterjee, P; Mukherjee, R K; Chaudhuri, B K

    2002-01-01

    Temperature-dependent magnetization and magnetoresistance of the Na doped La sub 1 sub - sub x Ca sub x sub sub - sub y Na sub y MnO sub 3 type samples with x=0.3 and 0 T sub p up to 320 K) conductivity data satisfy the variable range hopping (VRH) model. For T > 320 the small polaron hopping model is more appropriate than the VRH model. Even with a very small change of y, the density of states at the Fermi level N(E sub F) changes considerably. The resistivity of these materials measured under pulsed and continuous DC magnetic fields behaves in an identical fashion. The relaxation time (decay time of the magnetic pulse within the sample) varies with field strength, which indicates that, with a change of magnetic field, the ordering of spin in the ferromagnetic regime changes.

  18. Hydrothermal synthesis and characterization of (N(C{sub 2}H{sub 5}){sub 4}){sub 4}[VMo{sub 12}V{sub 2}O{sub 44}

    Energy Technology Data Exchange (ETDEWEB)

    Cevik, S.; Alkan, Z.; Poyraz, M. [Department of Chemistry, Science and Literature Faculty, Afyon Kocatepe University, Afyonkarahisar TR-03200 (Turkey); Sari, M. [Department of Physics Education, Education Faculty, Gazi University, Besevler-Ankara TR-06500 (Turkey); Bueyuekguengoer, O. [Department of Physics, Science and Literature Faculty, Ondokuz Mayis University, Kurupelit-Samsun TR-55139 (Turkey)

    2007-10-15

    The hydrothermal reaction of a mixture of Na{sub 2}MoO{sub 4}.2H{sub 2}O, V{sub 2}O{sub 5}, pyromellitic acid (1,2,4,5-C{sub 6}H{sub 2}(COOH){sub 4}), (C{sub 2}H{sub 5}){sub 4}NCl and 0,1 M H{sub 2}SO{sub 4} for 88 h at 180 C gives blue needle-like crystals of [V{sup IV}{sub 2}O{sub 2}(H{sub 2}O){sub 2} (C{sub 6}H{sub 2}(COO){sub 4})] in 20% yield (based on V) and dark blue prismatic crystals of the title compound, mixed-valance (N(C{sub 2}H{sub 5}){sub 4}){sub 4}[VMo{sub 12}V{sub 2}O{sub 44}], 1, in 12% yield (based on Mo). 1 was investigated by means of elemental analysis, thermogravimetry, Fourier Transform Infrared Spectroscopy and Single Crystal X-ray Diffraction Methods. Crystal data for the compound: monoclinic space group P2{sub 1}/c (No:14), a=13.7815(12) b=13.0271(9) c=21.189(2) Aa, {beta}=113.909(7) , Z=2. Although [XM{sub 14}O{sub 42}]{sup -n} (X=P,Si,Ge,V and M=Mo and/or V) cores have been previously determined, this is the first time that [VMo{sub 12}V{sub 2}O{sub 44}]{sup -4} core is synthesized and characterized. The structural difference between 1 and these HPOMs is the coordinational geometry of the central metal atoms. The central vanadium in 1 has an octahedral coordination geometry, whereas in literature, the central V, P, Si and Ge atoms in [V{sub 15}O{sub 42}]{sup -9} / [SiM{sub 8}V{sub 6}O{sub 42}]{sup -4}/[PM{sub 8}V{sub 6}O{sub 42}]{sup -5}/[GeM{sub 8}V{sub 6}O{sub 42}]{sup -4} have tetrahedral coordinational geometry. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Surface morphology analysis of nanostructured (Ba sub x , Sr sub 1 sub - sub x)TiO sub 3 thin films using fractal method

    CERN Document Server

    Hong, K J; Choi, W K; Cho, J C

    2003-01-01

    Based on the fractal theory, this paper uses scanning electron microscopy images to investigate the roughness characteristics of nanostructured (Ba Sr)TiO sub 3 thin films by sol-gel methods. The percentage grain area, surface fractal dimensions and 3D image are evaluated using image analysis methods. The thickness of the (Ba Sr)TiO sub 3 thin films was 260-280 nm. The surface fractal dimensions were increased with strontium doping, and grain area, were decreased with it. The fractal dimension and the grain areas of the (Ba sub 0 sub . sub 7 Sr sub 0 sub . sub 3)TiO sub 3 thin films were 1.81 and 81%. Based on the image analysis, the roughness height of 3D images as 256 levels was about 3 nm and its distribution was about 35-40% for the (Ba sub 0 sub . sub 8 Sr sub 0 sub . sub 2)TiO sub 3 and (Ba sub 0 sub . sub 7 Sr sub 0 sub . sub 3)TiO sub 3 thin films. The roughness height of the BST thin films was distributed from 35% to 40% ranging from 3 nm to 4 nm. By increasing the strontium doping, the roughness hei...

  20. LiV<sub>2sub>O>4sub>: A heavy fermion transition metal oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, Shinichiro [Iowa State Univ., Ames, IA (United States)

    1999-02-12

    The format of this dissertation is as follows. In the remainder of Chapter 1, brief introductions and reviews are given to the topics of frustration, heavy fermions and spinels including the precedent work of LiV<sub>2sub>O>4sub>. In Chapter 2, as a general overview of this work the important publication in Physical Review Letters by the author of this dissertation and collaborators regarding the discovery of the heavy fermion behavior in LiV<sub>2sub>O>4sub> is introduced [removed for separate processing]. The preparation methods employed by the author for nine LiV<sub>2sub>O>4sub> and two Li<sub>1+xsub>Ti>2-xsub>O>4sub> (x = 0 and 1/3) polycrystalline samples are introduced in Chapter 3. The subsequent structural characterization of the LiV<sub>2sub>O>4sub> and Li<sub>1+xsub>T>2-xsub>O>4sub> samples was done by the author using thermogravimetric analysis (TGA), x-ray diffraction measurements and their structural refinements by the Rietveld analysis. The results of the characterization are detailed in Chapter 3. In Chapter 4 magnetization measurements carried out by the author are detailed. In Chapter 5, after briefly discussing the resistivity measurement results including the single-crystal work by Rogers et al., for the purpose of clear characterization of LiV<sub>2sub>O>4sub> it is of great importance to introduce in the following chapters the experiments and subsequent data analyses done by his collaborators. Heat capacity measurements (Chapter 6) were carried out and analyzed by Dr. C.A. Swenson, and modeled theoretically by Dr. D.C. Johnston. In Chapter 7 a thermal expansion study using neutron diffraction by Dr. O. Chmaissem et al. and capacitance dilatometry measurements by Dr. C.A. Swenson are introduced. The data analyses for the thermal expansion study were mainly done by Dr. O. Chmaissem (for neutron diffraction) and Dr. C.A. Swendon (for dilatometry), with assistances by Dr. J

  1. A structural study of Ni-substituted Pb sub 2 Sr sub 2 YCu sub 3 O sub 8+. delta

    Energy Technology Data Exchange (ETDEWEB)

    Amador, U.; Garcia-Alvarado, F.; Moran, E.; Alario-Franco, M.A. (Dept. de Quimica Inorganica, Univ. Complutense de Madrid (Spain)); Rodriguez-Carjaval, J. (Inst. Laue-Langevin, Grenoble (France))

    1990-02-15

    Novel Pb{sub 2}Sr{sub 2}YCu{sub 3-x}Ni{sub x}O{sub 8} materials have been obtained. By means of powder neutron diffraction a structural study of a sample with x{approx equal}0.8 was performed. Ni cation substitutes approximately 27% of copper ions scattering entering the Cu(2) positions and forming (Cu{sub 0.6}Ni{sub 0.4})O{sub 2} planes. The crystal structure is described in the space group Cmmm. (orig.).

  2. Improving the Kinetics and Thermodynamics of Mg(BH<sub>4sub>)>2sub> for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Brandon [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Klebanoff, Lennie [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Stavila, Vitalie [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Heo, Tae Wook [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ray, Keith [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lee, Jonathan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Baker, Alex [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kang, ShinYoung [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Yu, Hui-Chia [Univ. of Michigan, Ann Arbor, MI (United States); Thornton, Katsuyo [Univ. of Michigan, Ann Arbor, MI (United States)

    2017-10-31

    The objective of this project is to (1) combine theory, synthesis, and characterization across multiple scales to understand the intrinsic kinetic and thermodynamic limitations in MgB<sub>2sub>/Mg(BH>4sub>)>2sub>; (2) construct and apply a flexible, validated, multiscale theoretical framework for modeling (de)hydrogenation kinetics of the Mg-B-H system and related metal hydrides; and (3) devise strategies for improving kinetics and thermodynamics, particularly through nanostructuring and doping. The project has an emphasis on understanding and improving rehydrogenation of MgB<sub>2sub>, which has generally been less explored and is key to enabling practical use.

  3. Magnetic circular dichroism of LaMn sub 1 sub - sub x Al sub x O sub 3 sub + subdelta series of samples

    CERN Document Server

    Banerjee, A; Krishnan, R V; Dasannacharya, B A; Muro, T; Saitoh, Y; Imada, S; Suga, S

    2003-01-01

    We report magnetic circular dichroism (MCD) studies on the polycrystalline LaMn sub 1 sub - sub x Al sub x O sub 3 sub + subdelta series with x=0-0.2. The Mn-2p MCD was recorded in the temperature range from 45 to 300 K for samples with x=0, 0.075, 0.1 and 0.15. It was seen that unlike ac-susceptibility no second transition in MCD was observed at lower temperatures in the samples with x>=0.075 indicating that it is not intrinsic to the samples but arise out of the dynamics of ferromagnetic clusters in the polycrystalline sample. More significantly, the MCD signal persists even 100 K above the ferromagnetic T sub C confirming that the observation of the magnetic correlation above T sub C in bulk measurement is intrinsic to this type of systems.

  4. The relationship between open volume defects and deposition conditions of superconducting thin-film YBa sub 2 Cu sub 3 O sub 7 sub - sub x

    CERN Document Server

    Zhou, X Y; Jiang, H; Bauer-Kugelmann, W; Duffy, J A; Koegel, G; Triftshaeuser, W

    1997-01-01

    The relationship between the open volume defects and the deposition conditions of superconducting thin-film YBa sub 2 Cu sub 3 O sub 7 sub - sub x was studied by the position lifetime technique. Using a low-energy pulsed positron system, positron lifetime as a function of implantation energy was measured on epitaxial superconducting thin-film YBa sub 2 Cu sub 3 O sub 7 sub - sub x deposited on yttrium stabilized cubic zirconia substrates (YSZ) with pulsed laser deposition in a partial pressure of air under different conditions. The results show that the type of open volume defect is independent of deposition conditions such as the substrate temperature, T sub s , and the air pressure, P sub a. The defect concentration increases with decreasing T sub s and increasing P sub a. (author). Letter-to-the-editor

  5. Two crystal structures of Ag sup + -and Tl sup + -exchanged zeolite X, Ag sub 2 sub 7 Tl sub 6 sub 5 -X and Ag sub 2 sub 3 Tl sub 6 sub 9 -X

    CERN Document Server

    Kim, S Y; Kim, Y

    2002-01-01

    Two crystal structures of dehydrated Ag sup + -and Tl sup + -exchanged zeolite X (Ag sub 2 sub 7 Tl sub 6 sub 5 -X and Ag sub 2 sub 3 Tl sub 6 sub 9 -X) have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1) .deg. C (a = 24.758(4) A, a = 24.947(4) A, respectively). Their structures were refined to the final error indices R sub 1 = 0.055 and wR sub 2 = 0.057 with 375 reflections, and R sub 1 = 0.058 and wR sub 2 = 0.057 with 235 reflections, respectively, for which I> 3 sigma(I). In the structure of Ag sub 2 sub 7 Tl sub 6 sub 5 -X, 27 Ag sup + ions were found at two crystallographic sites: 15 Ag sup + ions at site I at the center of the hexagonal prism and the remaining 12 Ag sup + ions at site II' in the sodalite cavity. Sixty-five Tl sup + ions were located at three crystallographic sites: 20 Tl sup + ions at site II opposite single six-rings in the supercage, 18 Tl sup + ions at site I' in the sodalite cavity opposite the D6Rs, and the remaining 27 Tl sup ...

  6. Tetrahedrally coordinated disordered Cu<sub>2sub>SnS>3sub>-Cu>2sub>ZnSnS>4sub>-ZnS alloys with tunable optical and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Erslev, Peter T.; Young, Matthew R.; Li, Jian V.; Siah, Sin Cheng; Chakraborty, Rupak; Du, Hui; Lad, Robert J.; Buonassisi, Tonio; Teeter, Glenn [NREL; (MIT); (Maine)

    2014-08-28

    A key requirement for large-scale deployment of photovoltaic technologies is the development of highly functional materials with controllable opto-electronic properties. In this work, we report on the room-temperature synthesis of disordered alloys of the Earth-abundant, tetrahedrally coordinated semiconductors Cu<sub>2sub>SnS>3sub>, Cu<sub>2sub>ZnSnS>4sub> (CZTS), and ZnS as (Cu<sub>2sub>SnS>3sub>)>1-xsub>(ZnS)x>. The resulting disordered semiconductors are found to have continuously and independently tunable optical and electronic properties. Quasi-isovalent alloying on the cation sublattice allows the optical band gap to be varied continuously from 1.1 eV to 2.8 eV. Aliovalent alloying leads to independent control of carrier concentration over at least three orders of magnitude. A conceptual framework describing these disordered materials is presented, in which the structural disorder, constrained by local tetrahedral coordination of both anions and cations, leads to the observed high degree of tunability of the opto-electronic properties. These materials are not only independently interesting, but the developed framework also applies to the opto-electronic properties of kesterite CZTS materials as well as provides a basis for the development of new semiconductors.

  7. Effects of SO sub 2 , SO sub 2 +NO sub 2 and SO sub 2 +NO sub 2 +O sub 3 on the CO sub 2 /H sub 2 O gas exchange of forest soil vegetation. Die Wirkungen von SO sub 2 , SO sub 2 +NO sub 2 und SO sub 2 +NO sub 2 +O sub 3 auf den CO sub 2 /H sub 2 O-Gaswechsel der Waldbodenvegetation

    Energy Technology Data Exchange (ETDEWEB)

    Both, R.; Steubing, L.; Fangmeier, A. (Giessen Univ. (Germany, F.R.). Inst. fuer Pflanzenoekologie)

    1989-01-01

    The ground vegetation of a beech forest was fumigated with sulphur dioxide (300 {mu}g SO{sub 2}/m{sup 3}), nitrogen dioxide (100 {mu}g NO{sub 2}/m{sup 3}) and ozone (200 {mu}g O{sub 3}/m{sup 3}) in transportable open-top chambers for four hours weekly. The pollutants were applied in three different treatments: SO{sub 2} alone, SO{sub 2} + NO{sub 2} and SO{sub 2} + NO{sub 2} + O{sub 3}. Ambient air plots served as controls. The CO{sub 2}/H{sub 2}O gas exchange was measured in four species, Allium ursinum L., Melica uniflora Retz., Oxalis acetosella L.; Viola reichenbachiana Jord., during the fumigations. The response to the fumigations was dependent on species, on treatment, and on PAR. SO{sub 2} alone reduced transpiration and photosynthesis of Allium ursinum. SO{sub 2} + NO{sub 2} caused depressions of these parameters in Oxalis acetosella and Viola reichenbachiana, but not in Allium ursinum and Melica uniflora. Treatments with SO{sub 2} + NO{sub 2} + O{sub 3} decreased the gas exchange of all investigated species. The variability of the response was higher at low (ambient) PAR-values (1-30{mu}E/m{sup 2*}s). Thus, significant differences between fumigated and control plants were only detected by comparing light saturation curves. (orig.).

  8. Microstrain in modulation-doped Al sub x Ga sub 1 sub - sub x N/GaN heterostructures

    CERN Document Server

    Tan Wei Shi; Shen Bo; Cai Hong Ling; Wu Xiao Shan; Jiang Shu Sheng; Zheng Wen Li; Jia Quan Jie; Jiang Xiao Ming

    2002-01-01

    Modulation-doped Al sub x Ga sub 1 sub - sub x N/GaN heterostructures with various thickness of Si-doped n-Al sub 0 sub . sub 2 sub 2 Ga sub 0 sub . sub 7 sub 8 N barrier (n-AlGaN) were deposited on (0001)-oriented sapphire (alpha-Al sub 2 O sub 3) by MOCVD. The reciprocal space mappings (RSMs) of symmetric reflection (0002) and asymmetric reflection (1014) were measured with the methods of high resolution X-ray diffraction (HRXRD). The results indicate that the microstructure and strain status of barrier correlate to those of the i-GaN layer. The strained barrier starts to be relaxed while its thickness is larger than 750 Angstrom and the critical thickness t sub c is larger than 500 Angstrom. The barrier holds an 'abnormal' relaxation status, which probably results from the internal defects of n-AlGaN and the strain relaxation status at the i-GaN/alpha-Al sub 2 O sub 3 interfaces

  9. Electronic structure and magnetism of YCo sub 5 , YNi sub 5 and YCo sub 3 Ni sub 2

    CERN Document Server

    Kitagawa, I; Yamada, H; Aoki, M

    1997-01-01

    Dependences of the magnetic moment on the lattice constant for binary and pseudo-binary compounds YCo sub 5 , YNi sub 5 and Y(Co sub 0 sub . sub 6 Ni sub 0 sub . sub 4) sub 5 with a hexagonal CaCu sub 5 -type structure are studied by an ab initio calculation on a self-consistent linear muffin-tin orbital method within the atomic sphere approximation. It is found that Co moments in YCo sub 5 decrease abruptly at a critical lattice constant smaller than the observed one. On the other hand, Ni moments in YNi sub 5 are shown to appear at a lattice constant a little larger than the observed one. Similar calculations are carried out for the ordered compound YCo sub 3 Ni sub 2 , where Co and Ni atoms occupy the 3g and 2c sites, respectively. It is shown that Co and Ni atoms in this compound lose their moments at a lattice constant slightly smaller than the observed one. It is also found that the Co atom on the 3g site in YCo sub 5 and YCo sub 3 Ni sub 2 has two magnetic states, a high-moment state and a low-moment o...

  10. Reversible Hydrogen Storage in a LiBH <sub>4sub> –C <sub>60sub> Nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Patrick A.; Teprovich, Joseph A.; Peters, Brent; Wheeler, Joseph; Compton, Robert N.; Zidan, Ragaiy

    2013-11-07

    Reversible hydrogen storage in a LiBH<sub>4sub>:C>60sub> nanocomposite (70:30 wt. %) synthesized by solvent-assisted mixing has been demonstrated. During the solvent-assisted mixing and nanocomposite formation, a chemical reaction occurs in which the C<sub>60sub> cages are significantly modified by polymerization as well as by hydrogenation (fullerane formation) in the presence of LiBH{sub 4}. We have determined that two distinct hydrogen desorption events are observed upon rehydrogenation of the material, which are attributed to the reversible formation of a fullerane (C<sub>60sub>Hx>) as well as a LiBH4 species. This system is unique in that the carbon species (C<sub>60sub>) actively participates in the hydrogen storage process which differs from the common practice of melt infiltration of high surface area carbon materials with LiBH<sub>4sub> (nanoconfinment effect). This nanocomposite demonstrated good reversible hydrogen storage properties as well as the ability to absorb hydrogen under mild conditions (pressures as low as 10 bar H<sub>2sub> or temperatures as low as 150°C). The nanocomposite was characterized by TGA-RGA, DSC, XRD, LDI-TOF-MS, FTIR, 1H NMR, and APPI MS.

  11. Tuning of magnetic properties and Kondo effect by Cu concentration in Ce(Pd sub 1 sub - sub x Cu sub x) sub 2 Al sub 3

    CERN Document Server

    Sun, P; Huo, D; Kuwai, T; Lu, Q

    2003-01-01

    The electrical resistivity, magnetic susceptibility and specific heat measurements were performed on Ce(Pd sub 1 sub - sub x Cu sub x) sub 2 Al sub 3 (x = 0.0-0.7) system to investigate the effects induced by Cu substitution in the heavy fermion compound CePd sub 2 Al sub 3. A dramatic evolution of the magnetic properties was observed with the substitution of Pd by Cu: (1) a small amount of Cu (x < 0.1) in CePd sub 2 Al sub 3 leads to a rapid decrease of the antiferromagnetic transition temperature T sub N; passing through a crossover region without a long-range magnetic order, a ferromagnetic-like state, which reveals an enhanced magnetic susceptibility and a distinct peak in the specific heat curve at low temperatures, occurs around x = 0.1-0.4; (3) by furthering the substitution through a second crossover region, however, the antiferromagnetic ordering is recovered close to x = 0.5 - 0.7. A decrease tendency of the Kondo temperature T sub K with increasing x is derived from the analysis on the specific ...

  12. Non-conventional superconducting fluctuations in Ba(Fe<sub>1-xsub>Rhx)>2sub>As>2sub> iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bossoni, L. [Univ. of Pavia (Italy); Romano, L. [Univ. of Parma (Italy); Canfield, Paul C. [Ames Lab., Ames, IA (United States); Lascialfari, A. [Univ. degli Studi di Milano (Italy)

    2014-09-17

    We measured the static uniform spin susceptibility of Ba(Fe<sub>1-xsub>Rhx)>2sub>As>2sub> iron-based superconductors, over a broad range of doping (0.041x0.094) and magnetic fields. At small fields (H ≤ 1 kOe) we observed, above the transition temperature T<sub>c>, the occurrence of precursor diamagnetism, which is not ascribable to the Ginzburg–Landau theory. On the contrary, our data agree with a phase fluctuation model, which has been used to interpret a similar phenomenology occurring in the high-Tc cuprate superconductors. Additionally, in the presence of strong fields, the unconventional fluctuating diamagnetism is suppressed, whereas Ginzburg–Landau fluctuations are found, in agreement with literature.

  13. Measurement of the branching fraction Br (B0<sub>s> → D<sub>s*Ds>* using the D0 detector at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Walder, James William [Lancaster Univ. (United Kingdom)

    2008-05-01

    This thesis describes a measurement of the branching fraction Br (B0<sub>s> → D<sub>s*Ds>*) made using a data sample collected from proton-antiproton collisions at a centre-of-mass energy of 1.96 TeV, corresponding to approximately 1.3 fb-1 of integrated luminosity collected in 2002--2006 by the D0 detector at the Fermilab Tevatron Collider. One D*<sub>s> meson was partially reconstructed in the decay D<sub>s> → Φμv, and the other D*<sub>s> meson was identified using the decay D<sub>s> → Φπ where no attempt was made to distinguish D<sub>s> and D*<sub>s> states. The resulting measurement is Br (B0<sub>s> → D<sub>s*Ds>*) = 0.039+0.019<sub>-0.017sub>(stat) +0.016<sub>-0.015sub>(syst). This was subsequently used to estimate the width difference ΔΓCP<sub>s> in the B0<sub>s>-$\\bar{B}$0<sub>s> system: ΔΓCP<sub>s/Γs> = 0.079+0.038<sub>-0.035sub>(stat)+0.031<sub>-0.030sub>(syst), and is currently one of the most precise estimates of this quantity and consistent with the Standard Model.

  14. Raman scattering study of Nd sub 1 sub - sub x Sr sub x MnO sub 3 (x = 0.3, 0.5)

    CERN Document Server

    Choi, K Y; Güntherodt, G; Pattabiraman, M; Rangarajan, G; Gnezdilov, V P; Balakrishnan, G; Paul, D M; Lees, M R

    2003-01-01

    We report on polarized Raman scattering of single crystals of Nd sub 1 sub - sub x Sr sub x MnO sub 3 (x = 0.3, 0.5). Raman spectra of Nd sub 0 sub . sub 7 Sr sub 0 sub . sub 3 MnO sub 3 show a significant change through the metal-insulator transition. In the ferromagnetic metallic phase phonon modes grow in intensity and number while the electronic continuum becomes more pronounced. We suggest that these effects are due to the strong competition between the localization and the delocalization of carriers which is the origin of the largest colossal magnetoresistance effect ever reported for the manganites. Raman spectra of Nd sub 0 sub . sub 5 Sr sub 0 sub . sub 5 MnO sub 3 , upon cooling through the charge-ordering temperature T sub C sub O = 148 K, exhibit several new lines which undergo a substantial hardening. This hardening is interpreted as a freezing of the Jahn-Teller distortions with a gradual decrease of a fraction of the ferromagnetic phase in the CE-type charge/orbital ordered state.

  15. Structural properties of Y<sub>2sub>O>3sub>–Al>2sub>O>3sub> liquids and glasses: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Wilding, Martin C.; Wilson, Mark; McMillan, Paul F.; Benmore, Chris J.; Weber, J. K. R.; Deschamps, Thierry; Champagnon, Bernard

    2015-01-01

    Liquids in the system Y<sub>2sub>O>3sub>–Al>2sub>O>3sub> have been the subject of considerable study because of the reported occurrence of a first-order density and entropy-driven liquid-liquid phase transition (LLPT) in the supercooled liquid state. The observations have become controversial because of the presence of crystalline material that can be formed simultaneously and that can mask the nucleation and growth of the lower density liquid. The previous work is summarized here along with arguments for and against the different viewpoints. Also two studies have been undertaken to investigate the LLPT in this refractory system with emphasis on determining the structure of unequivocally amorphous materials. These include the in situ high energy X-ray diffraction (HEXRD) of supercooled Y<sub>2sub>O>3sub>–Al>2sub>O>3sub> liquids and the low frequency vibrational dynamics of recovered glasses. Manybody molecular dynamics simulations are also used to interpret the results of both studies. The HEXRD measurements, combined with aerodynamic levitation and rapid data acquisition techniques, show that for the 20 mol% Y<sub>2sub>O>3sub> (i.e. AlY20) liquid there is a shift in the position of the first peak in the diffraction pattern over a narrow temperature range (2100-1800 K) prior to crystallization. Microbeam Raman spectroscopy measurements made on AlY20 glasses clearly show contrasting spectra in the low frequency part of the spectrum for low(LDA) and high-density (HDA) glassy regions. The molecular dynamics simulations identify contrasting coordination environments around oxygen anions for the high- (HDL) and low-density (LDL) liquids. (C) 2014 Elsevier B.V. All rights reserved.

  16. X-ray and NQR studies of bromoindate(III) complexes. [C{sub 2}H{sub 5}NH{sub 3}]{sub 4}InBr{sub 7}, [C(NH{sub 2}){sub 3}]{sub 3}InBr{sub 6}, and [H{sub 3}NCH{sub 2}C(CH{sub 3}){sub 2}CH{sub 2}NH{sub 3}]InBr{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Iwakiri, Takeharu; Ishihara, Hideta [Saga Univ. (Japan). Faculty of Culture and Education; Terao, Hiromitsu [Tokushima Univ. (Japan). Faculty of Integrated Arts and Sciences; Lork, Enno; Gesing, Thorsten M. [Bremen Univ. (Germany). Inst. of Inorganic Chemistry and Crystallography

    2017-03-01

    The crystal structures of [C{sub 2}H{sub 5}NH{sub 3}]{sub 4}InBr{sub 7}(1), [C(NH{sub 2}){sub 3}]{sub 3}InBr{sub 6}(2), and [H{sub 3}NCH{sub 2}C(CH{sub 3}){sub 2}CH{sub 2}NH{sub 3}]InBr{sub 5}(3) were determined at 100(2) K: monoclinic, P2{sub 1}/n, a=1061.94(3), b=1186.40(4), c=2007.88(7) pm, β= 104.575(1) , Z=4 for 1; monoclinic, C2/c, a=3128.81(12), b=878.42(3), c=2816.50(10) pm, β=92.1320(10) , Z=16 for 2; orthorhombic, P2{sub 1}2{sub 1}2{sub 1}, a=1250.33(5), b=1391.46(6), c=2503.22(9) pm, Z=4 for 3. The structure of 1 contains an isolated octahedral [InBr{sub 6}]{sup 3-} ion and a Br{sup -} ion. The structure of 2 contains three different isolated octahedral [InBr{sub 6}]{sup 3-} ions. The structure of 3 has a corner-shared double-octahedral [In{sub 2}Br{sub 11}]{sup 5-} ion and an isolated tetrahedral [InBr{sub 4}]{sup -} ion. The {sup 81}Br nuclear quadrupole resonance (NQR) lines of the terminal Br atoms of the compounds are widely spread in frequency, and some of them show unusual positive temperature dependence. These observations manifest the N-H..Br-In hydrogen bond networks developed between the cations and anions to stabilize the crystal structures. The {sup 81}Br NQR and differential thermal analysis (DTA) measurements have revealed the occurrence of unique phase transitions in 1 and 3. When the bond angles were estimated from the electric field gradient (EFG) directions calculated by the molecular orbital (MO) methods, accurate values were obtained for [InBr{sub 6}]{sup 3-} of 1 and for [In{sub 2}Br{sub 11}]{sup 5-} and [InBr{sub 4}]{sup -} of 3, except for several exceptions in those for the latter two ions. On the other hand, the calculations of {sup 81}Br NQR frequencies have produced up to 1.4 times higher values than the observed ones.

  17. Upper limit to magnetism in LaAIO<sub>3sub>/SrTiO>3sub> heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimmons, Michael R [Los Alamos National Laboratory

    2012-02-27

    In 2004 Ohtomo and Hwang reported unusually high conductivity in LaAl0<sub>3sub> and SrTi0<sub>3sub> bilayer samples. Since then, metallic conduction, superconductivity, magnetism, and coexistence of superconductivity and ferromagnetism have been attributed to LaAl0<sub>3sub>/SrTi0<sub>3sub> interfaces. Very recently, two studies have reported large magnetic moments attributed to interfaces from measurement techniques that are unable to distinguish between interfacial and bulk magnetism. Consequently, it is imperative to perform magnetic measurements that by being intrinsically sensitive to interface magnetism are impervious to experimental artifacts suffered by bulk measurements. Using polarized neutron reflectometry we measured the neutron spin dependent reflectivity from four LaAl0<sub>3sub>/SrTi0<sub>3sub> superlattices. Our results indicate the upper limit for the magnetization averaged over the lateral dimensions of the sample induced by an 11 T magnetic field at 1.7 K is less than 2 G. SQUID magnetometry of the neutron superlattice samples sporadically finds an enhanced moment (consistent with past reports), possibly due to experimental artifacts. These observations set important restrictions on theories which imply a strongly enhanced magnetism at the interface between LaAI0<sub>3sub> and SrTi0<sub>3sub>.

  18. Ion Implantation of In<sub>0.53sub>Ga>0.47sub>As

    Energy Technology Data Exchange (ETDEWEB)

    Almonte, Marlene Isabel [Univ. of California, Berkeley, CA (United States)

    1999-05-01

    Studies of the effects of implanation in In<sub>0.53sub>Ga>0.47sub>As due to damage by implantation of Ne+ ions and to compensation by implantation of Fe+ ions are reported in this thesis.

  19. Correlation functions in the CFT sub d /AdS sub d sub + sub 1 correspondence

    CERN Document Server

    Freedman, D Z; Matusis, A; Rastelli, L

    1999-01-01

    Conformal techniques are applied to the calculation of integrals on AdS sub d sub + sub 1 space which define correlators of composite operators in the superconformal field theory on the d-dimensional boundary. The 3-point amplitudes for scalar fields of arbitrary mass and gauge fields in the AdS supergravity are calculated explicitly. For three gauge fields we compare in detail with the known conformal structure of the SU(4) flavor current correlator of the N = 4, d = 4 SU(N) SYM theory. Results agree with the free field approximation as would be expected from superconformal non-renormalization theorems. In studying the Ward identity relating to for (non-marginal) scalar composite operators O sup I , we find that there is a subtlety in obtaining the normalization of from the supergravity action integral.

  20. CF.sub.4 laser

    Science.gov (United States)

    Wittig, Curt; Tiee, Joe J.

    1979-01-01

    A CF.sub.4 laser for producing near 16 .mu.m radiation utilizing a line tunable CO.sub.2 laser as an optical pumping source. The device uses a cryogenically cooled optically pumped cell containing molecular CF.sub.4 gas. An optical resonant cavity formed around the optically pumped cell induces oscillations of near 16 .mu.m radiation from the .nu..sub.2 +.nu..sub.4 .fwdarw..nu..sub.2 transition in the molecular CF.sub.4 gas.

  1. Fabrication of full high-T sub c superconducting YBa sub 2 Cu sub 3 O sub 7 sub - sub x trilayer junctions using a polishing technique

    CERN Document Server

    Kuroda, K; Takami, T; Ozeki, T

    2003-01-01

    We have successfully fabricated full high-T sub c superconducting YBa sub 2 Cu sub 3 O sub 7 sub - sub x (YBCO)/PrBa sub 2 Cu sub 3 O sub 7 sub - sub x (PBCO)/YBCO trilayer junctions, which have a simple device structure, such as a Pb-alloy-based Josephson tunneling junction. It has been demonstrated that a polishing technique is extremely useful in the fabrication process: it is effective in smoothing a coarse surface and gentling the slopes of the edges, or decreasing the slope angles. Owing to the polishing technique, the PBCO barrier layer and the upper YBCO layer have been notably thinned: the thicknesses of these layers are 10 nm and 250 nm, respectively. Junctions with the dimensions of 5 mu m x 5 mu m showed resistively shunted junction-like current-voltage curves with a typical critical current density of 110 A/cm sup 2 at 4.2 K. Furthermore, the operation of superconducting quantum interference devices has been demonstrated. (author)

  2. A structural study of the pseudo-binary mercury chalcogenide alloy HgSe sub 0 sub . sub 7 S sub 0 sub . sub 3 at high pressure

    CERN Document Server

    Kozlenko, D P; Hull, S; Knorr, K; Savenko, B N; Shchennikov, V V; Voronin, V I

    2002-01-01

    The structure of the pseudo-binary mercury chalcogenide alloy HgSe sub 0 sub . sub 7 S sub 0 sub . sub 3 has been studied by means of X-ray and neutron powder diffraction at pressure up to 8.5 GPa. A phase transition from the cubic zinc blende structure to the hexagonal cinnabar structure was observed at P approx 1 GPa. The obtained structural parameters were used for the analysis of the geometrical relationship between the zinc blende and the cinnabar phases. The zinc blende-cinnabar phase transition is discussed in the framework of the Landau theory of phase transitions. It was found that the possible order parameter for the structural transformation is the spontaneous strain e sub 4. This assignment agrees with previously observed high pressure behaviour of the elastic constants of other mercury chalcogenides

  3. Microstructural analyses of B{sub 4}C-CeO{sub 2} and B{sub 4}C-La{sub 2}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Tatsuaki, E-mail: sakamoto.tatsuaki@eng.ehime-u.ac.jp [Department of Materials Science and Biotechnology, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Sun, Shu-Chen [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Furuno, Tomoya; Kajioka, Michio [Graduate Student of Ehime Univerisity, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Nakai, Kiyomichi [Department of Materials Science and Biotechnology, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Kurishita, Hiroaki [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Kobayashi, Sengo [Department of Materials Science and Biotechnology, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Wu, Wen-Yuan; Tu, Gan-Feng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Matsuda, Seiji [Department of Anatomy and Embryology, Ehime University, Shizugawa, Toon 791-0295 (Japan)

    2011-10-01

    Effects of additions of CeO{sub 2} and La{sub 2}O{sub 3} on microstructure and mechanical properties of B{sub 4}C fabricated under and without hot press have been investigated. Vickers hardness and fracture strength are increased by hot press due to the reduction of porosity because the sintering rate is enhanced. Hardness is increased by the reduction of porosity because crack probably occurs when the hardness is measured due to pore as an initiation point of crack. Hardness increases with increasing additions of CeO{sub 2} and La{sub 2}O{sub 3} because porosity decreases due to the formation of CeB{sub 6} and LaB{sub 6} on the grain boundary of B{sub 4}C, respectively. The borides are formed through reaction between solid phases, which might induce coherent boundary between boride and B{sub 4}C. Such coherency also contributes to strengthening the grain boundary of B{sub 4}C. The addition of CeO{sub 2} enhances the sintering rate more than that of La{sub 2}O{sub 3}, resulting in higher hardness of B{sub 4}C-CeO{sub 2} than that of B{sub 4}C-La{sub 2}O{sub 3}.

  4. Densification and mechanical properties of sintered Al{sub 2}O{sub 3}-Y{sub 3}Al{sub 5}O{sub 12} ceramic composite

    Energy Technology Data Exchange (ETDEWEB)

    Paneto, Flavio Jose; Pereira, Joaquim Lopes; Oliveira, Jean de Lima; Jesus Filho, Edson de; Silva, Leandro Anselmo da; Cabral, Ricardo de Freitas; Santos, Claudinei dos [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Lima, Eduardo de Sousa [Institutlo Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil)

    2014-06-15

    In this work, Al{sub 2}O{sub 3}-Y{sub 3}Al{sub 5}O{sub 12} ceramic composites were developed with different proportions of Al{sub 2}O{sub 3}-Y{sub 3}Al{sub 5}O{sub 12}, which were mixed and compacted at different pressures of 40MPa to 100MPa, being consequently sintered at 1600 deg C-2h. The sintered samples were characterized by X-ray diffraction presenting α-Al{sub 2}O{sub 3} and Y{sub 3}Al{sub 5}O{sub 12} as crystalline phases. Samples with relative densities ranging from 78 to 80% and 87 to 91% were obtained depending on the composition and the compaction pressure used. The hardness values obtained were of 1010 to 1080HV and 370- 470HV, for mixes Al{sub 2}O{sub 3}-Y{sub 3}Al{sub 5}O{sub 12} having the composition with levels of 20 and 36.5wt.%, respectively. (author)

  5. Structural phase transitions in the perovskite-type compound (C sub 1 sub 8 H sub 3 sub 7 NH sub 3) sub 2 MnCl sub 4

    CERN Document Server

    Lee, C H; Lee, C E; Kang, J K

    1999-01-01

    The perovskite-type layered-structure compound (C sub 1 sub 8 H sub 3 sub 7 NH sub 3) sub 2 MnCl sub 4 was studied by means of nuclear magnetic resonance and electron paramagnetic resonance measurements. As a result, a novel phase transition associated with the inorganic planes, as well as two structural phase transitions attributed to the hydrocarbon chains, was identified and characterized.

  6. Some structural characteristics of sulfates forming in the system of Ce(SO/sub 4/)/sub 2/-K/sub 2/SO/sub 4/-H/sub 2/SO/sub 4/-H/sub 2/O

    Energy Technology Data Exchange (ETDEWEB)

    Rogachev, D.L.; Bondar' , S.A.; Letetskaya, M.A.; Rys' kina, M.P. (AN SSSR, Apatity. Inst. Khimii i Tekhnologii Redkikh Ehlementov i Mineral' nogo Syr' ya Kol' skogo Filiala)

    1983-02-01

    Refractive indexes, symmetry, lattice parameters and space group of five sulfates, separated during investigation into Ce(SO/sub 4/)/sub 2/-K/sub 2/SO/sub 4/-H/sub 2/SO/sub 4/-H/sub 2/O system at 50-150 deg C were determined. The properties of separated compounds were correlated with the properties of cerium and rubidium sulfates. Powder radiograms of these compounds are given.

  7. The phase diagram and critical behaviour of the easy-plane antiferromagnet CsNi sub 0 sub . sub 9 sub 8 Fe sub 0 sub . sub 0 sub 2 Cl sub 3

    CERN Document Server

    Winkelmann, M; Schneider, R; Enderle, M; Asano, T; Ajiro, Y

    1997-01-01

    Neutron diffraction measurements have been performed to determine the magnetic phase diagram of the stacked-triangular antiferromagnet CsNi sub 0 sub . sub 9 sub 8 Fe sub 0 sub . sub 0 sub 2 Cl sub 3 between T = 1.8 K and T = 6 K in static magnetic fields up to B = 5 T applied perpendicular to the c-axis. The substitution of a few per cent of Fe sup 2 sup + for Ni sup 2 sup + leads to a compensation of the weak Ising anisotropy of the pure compound, and induces an XY-anisotropy in the doped system. The magnetic phase diagram displays three different magnetically ordered phases with a multicritical point at B = 2 T and T = 4.3 K. The phase diagram and the spin configurations of the different phases are found to be consistent with theoretical predictions for stacked-triangular antiferromagnets with a weak easy-plane anisotropy. The spin ordering at zero field exhibits a 120 deg. structure in the basal plane with inherent XY- and chiral degeneracy. We have determined the critical exponent of the sublattice magne...

  8. SO<sub>2sub>-Resistant Immobilized Amine Sorbents for CO<sub>2sub> Capture

    Energy Technology Data Exchange (ETDEWEB)

    Tumuluri, Uma [Univ. of Akron, OH (United States)

    2014-01-01

    The solid amine sorbent for CO<sub>2sub> capture process has advantages of simplicity and low operating cost compared to the MEA (monoethanolamine) process. Solid amine sorbents reported so far suffered from either low CO<sub>2sub> capture capacity or low stability in the flue gas environment. This project is aimed at developing a SO<sub>2sub>-resistant solid amine sorbent for capturing CO<sub>2sub> from coal–fired power plants with SCR/FGD which emits SO<sub>2sub>ranging from 15 to 30 ppm and NO ranging from 5 to 10 ppm. The amine sorbent we developed in a previous project degraded rapidly with 65% decrease in the initial capture capacity in presence of 1% SO<sub>2sub>. This amine sorbent was further modified by coating with polyethyleneglycol (PEG) to increase the SO<sub>2sub>-resistance. Polyethylene glycol (PEG) was found to decrease the SO<sub>2sub>-amine interaction, resulting in the decrease in the maximum SO desorption temperature (Tmax ) of amine sorbent. The PEG-coated amine sorbent exhibited higher stability with only 40% decrease in the initial capture capacity compared to un-coated amine sorbents. The cost of the solid amine sorbent developed in this project is estimated to be less than $7.00/lb; the sorbent exhibited CO<sub>2sub> capture capacity more than 2.3 mmol/g. The results of this study provided the scientific basis for further development of SO<sub>2sub>-resistant sorbents.

  9. Etching of UO<sub>2sub> in NF<sub>3sub> RF Plasma Glow Discharge

    Energy Technology Data Exchange (ETDEWEB)

    Veilleux, John M. [Univ. of California, Berkeley, CA (United States)

    1999-08-01

    A series of room temperature, low pressure (10.8 to 40 Pa), low power (25 to 210 W) RF plasma glow discharge experiments with UO<sub>2sub> were conducted to demonstrate that plasma treatment is a viable method for decontaminating UO<sub>2sub> from stainless steel substrates. Experiments were conducted using NF<sub>3sub> gas to decontaminate depleted uranium dioxide from stainless-steel substrates. Depleted UO<sub>2sub> samples each containing 129.4 Bq were prepared from 100 microliter solutions of uranyl nitrate hexahydrate solution. The amorphous UO<sub>2sub> in the samples had a relatively low density of 4.8 gm/cm<sub>3sub>. Counting of the depleted UO<sub>2sub> on the substrate following plasma immersion was performed using liquid scintillation counting with alpha/beta discrimination due to the presence of confounding beta emitting daughter products, 234Th and 234Pa. The alpha emission peak from each sample was integrated using a gaussian and first order polynomial fit to improve quantification. The uncertainties in the experimental measurement of the etched material were estimated at about ± 2%. Results demonstrated that UO<sub>2sub> can be completely removed from stainless-steel substrates after several minutes processing at under 200 W. At 180 W and 32.7 Pa gas pressure, over 99% of all UO<sub>2sub> in the samples was removed in just 17 minutes. The initial etch rate in the experiments ranged from 0.2 to 7.4 μm/min. Etching increased with the plasma absorbed power and feed gas pressure in the range of 10.8 to 40 Pa. A different pressure effect on UO<sub>2sub> etching was also noted below 50 W in which etching increased up to a maximum pressure, ~23 Pa, then decreased with further increases in pressure.

  10. The fabrication and performance of YBa<sub>2sub>Cu>3sub>O>7-xsub> SQUID magnetometers

    Energy Technology Data Exchange (ETDEWEB)

    Kingston, John Joseph [Univ. of California, Berkeley, CA (United States)

    1992-07-01

    To enhance the SQUID`s field sensitivity, it is coupled to a flux transformer, a closed superconducting circuit consisting of a pickup loop, to which a signal is applied, connected in series to an input coil, which is inductively coupled to the SQUID. To fabricate an optimal flux transformer, one must use more than one superconducting thin-film layer, each of which is patterned into narrow strips or wires. Some wires from different layers cross, yet remain electrically isolated, to form crossovers, while in other places there must be superconducting contact between wires from different layers. Together, the superconducting wire, superconducting-superconducting contact and the superconducting crossover constitute a superconducting interconnect or multilayer wiring technology. We discuss the development of an interconnect technology involving the high transition temperature (T<sub>c>) superconductor YBa<sub>2sub>Cu>3sub>O>7-xsub> (YBCO). Because of the need for epitaxial growth there are limits on materials for the insulating layer separating the YBCO films in multilayer structures, and on deposition and patterning techniques. We discuss the use of pulsed laser deposition in conjunction with patterning by shadow masks and later by photolithography to produce interconnects, multiturn input coils, and flux transformers. We also discuss the performance of SQUID magnetometers, in which a flux transformer fabricated on one substrate is coupled to a SQUID fabricated on another. The first magnetometers were hybrids -- high T<sub>c> transformers coupled to low T<sub>c> SQUIDS, while later ones had both high T<sub>c> transformers and SQUIDs and could operate immersed in liquid nitrogen. We report on a magnetometer with a magnetic field sensitivity at lHz of about 2pTHz-1/2 at 77K, that was successfully used to perform magnetocardiograms on human subjects.

  11. Proton form factor ratio, μ<sub>psub>G<sub>Esub>P/G<sub>M>P from double spin asymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Habarakada Liyanage, Anusha Pushpakumari [Hampton Univ., Hampton, VA (United States)

    2013-08-01

    The form factors are fundamental properties of the nucleon representing the effect of its structure on its response to electromagnetic probes such as electrons. They are functions of the four-momentum transfer squared Q2 between the electron and the proton. This thesis reports the results of a new measurement of the ratio of the electric and magnetic form factors of the proton up to Q2 = 5.66 (GeV/c)2 using the double spin asymmetry with a polarized beam and target. Experiment E07-003 (SANE, Spin Asymmetries of the Nucleon Experiment) was carried out in Hall C at Jefferson Lab in 2009 to study the proton spin structure functions with a dynamically polarized ammonia target and longitudinally polarized electron beam. By detecting elastically scattered protons in the High-Momentum Spectrometer (HMS) in coincidence with the electrons in the Big Electron Telescope Array (BETA), elastic measurements were carried out in parallel. The elastic double spin asymmetry allows one to extract the proton electric to magnetic form factor ratio Gp<sub>E/GpM> at high-momentum transfer, Q2= 5.66 (GeV/c)2. In addition to the coincidence data, inclusively scattered electrons from the polarized ammonia target were detected by HMS, which allows to measure the beam-target asymmetry in the elastic region with the target spin nearly perpendicular to the momentum transfer, and to extract Gp<sub>E/GpM> at low Q2= 2.06 (GeV/c)2. This alternative measurement of Gp<sub>E/GpM> has verified and confirmed the dramatic discrepancy at high Q2 between the Rosenbluth and the recoil-polarization-transfer iv method with a different measurement technique and systematic uncertainties uncorrelated to those of the recoil-polarization measurements. The measurement of the form factor ratio at Q2 = 2

  12. Molybdenum and tungsten complexes of S[sub 2]CPMe[sub 3] and related ligands. Crystal and molecular structures of W([eta][sup 3]-S[sub 2]CPMe[sub 3])(CO)[sub 2](PMe[sub 3])[sub 2], [Mo([eta][sup 2]-S[sub 2]C(H)PMe[sub 3])(CO)[sub 2](PMe[sub 3])[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, A.; Pastor, A.; Pizzano, A.; Sanchez, L.; Carmona, E. (Universidad de Sevilla, CSIC (Spain) Instituto de Ciencia de Materialses, Serrano, Madrid (Spain)); Gutierrez-Puebla, E.; Monge, A.; Ruiz, C. (Universidad Complutense de Madrid (Spain))

    1993-11-24

    The known compound Mo(S[sub 2]CPMe[sub 3])(CO)[sub 2](PMe[sub 3])[sub 2] (1a) and the newly prepared tungsten analog W(S[sub 2]CPMe[sub 3])-(CO)[sub 2](PMe[sub 3])[sub 2] (1b), obtained by HCl elimination from WH(Cl)(CO)[sub 2](PMe[sub 3])[sub 3] upon treatment with CS[sub 2] and PMe[sub 3], contain a trihapto-bonded S,S[prime],C-trimethylphosphonium dithiocarboxylate ligand as demonstrated by X-ray studies carried out with 1b. Interaction of compounds 1 with protic acids affords the dithioformate species [M([eta][sup 2]-S[sub 2]C-(H)PMe[sub 3])(CO)[sub 2](PMe[sub 3])[sub 2

  13. Valence transition between Eu sup 2 sup + state and Eu sup 3 sup + state in Eu sub x Y sub 1 sub - sub x Pd sub 2 Si sub 2 and Eu sub x La sub 1 sub - sub x Pd sub 2 Si sub 2

    CERN Document Server

    Sakurai, J; Fukuda, S; Mitsuda, A; Isikawa, Y

    2003-01-01

    In EuPd sub 2 Si sub 2 , the valence transition of Eu atoms between the Eu sup 2 sup + state and the Eu sup 3 sup + state takes place when the temperature of the sample changes. In the present study, we prepared Eu sub x Y sub 1 sub - sub x Pd sub 2 Si sub 2 and Eu sub x La sub 1 sub - sub x Pd sub 2 Si sub 2 , in which the Eu atoms of EuPd sub 2 Si sub 2 are systematically substituted by non-magnetic Y or La atoms, and we have measured the magnetic susceptibility chi, the electric resistivity rho and the thermoelectric power S. We found that the temperature of the valence transition of Eu ions is only very weakly dependent on the alloying concentration x of Eu atoms. In addition, the notable structures of the S(T) curves were observed for these samples, which we understand in term of the anomalies of the relaxation time of conduction electrons interacting with the Eu 4f sup 7 virtual bound state. In this respect, the valence transition of Eu ions in this study makes a contrast with the Kondo problems of the ...

  14. Solvate Structures and Computational/Spectroscopic Characterization of LiBF<sub>4sub> Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Seo, D. M.; Boyle, Paul D.; Allen, Joshua L.; Han, Sang D.; Jonsson, Erlendur; Johansson, Patrik; Henderson, Wesley A.

    2014-07-21

    Crystal structures have been determined for both LiBF<sub>4sub> and HBF<sub>4sub> solvates—(acetonitrile)<sub>2sub>:LiBF>4sub>, (ethylene glycol diethyl ether)<sub>1sub>:LiBF>4sub>, (diethylene glycol diethyl ether)1:LiBF<sub>4sub>, (tetrahydrofuran)<sub>1sub>:LiBF4, (methyl methoxyacetate)<sub>1sub>:LiBF>4sub>, (suc-cinonitrile)<sub>1sub>:LiBF>4sub>, (N,N,N',N",N"-pentamethyldiethylenetriamine)1:HBF<sub>4sub>, (N,N,N',N'-tetramethylethylenediamine)<sub>3/2sub>:HBF>4sub> and (phenanthroline)<sub>2sub>:HBF>4sub>. These, as well as other known LiBF<sub>4sub> solvate structures, have been characterized by Raman vibrational spectroscopy to unambiguously assign the anion Raman band positions to specific forms of BF<sub>4sub>-...Li+ cation coordination. In addition, complementary DFT calculations of BF<sub>4sub>-...Li+ cation complexes have provided additional insight into the challenges associated with accurately interpreting the anion interactions from experimental Raman spectra. This information provides a crucial tool for the characterization of the ionic association interactions within electrolytes.

  15. Compositions of supersaturated solutions for enhanced growth of {alpha}-NiSO{sub 4} . 6H{sub 2}O, Me{sub 2}Ni(SO{sub 4}){sub 2} . 6H{sub 2}O, MeH{sub 2}PO{sub 4} [Me = Li, Na, K, Rb, Cs, NH{sub 4}], and K(H{sub x}D{sub 1-x}){sub 2}PO{sub 4} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Soboleva, L. V., E-mail: afkonst@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2008-05-15

    The possibility of determining the optimal compositions and temperatures of supersaturated solutions for enhanced growth of single crystals of congruently and incongruently dissolving solid phases from the solubility diagrams of ternary systems is shown, and this approach is justified. The NiSO{sub 4}-H{sub 2}SO{sub 4}-H{sub 2}O, Me{sub 2}SO{sub 4}-NiSO{sub 4}-H{sub 2}O, and Me{sub 2}O-P{sub 2}O{sub 5}-H{sub 2}O(D{sub 2}O) systems have been used to determine the optimal compositions and temperatures of supersaturated solutions for growth of {alpha}-NiSO{sub 4} . 6H{sub 2}O, Me{sub 2}Ni(SO{sub 4}){sub 2} . 6H{sub 2}O, MeH{sub 2}PO{sub 4} [Me = Li, Na, K, Rb, Cs, NH{sub 4}], and K (H{sub x} D{sub 1-x}){sub 2}PO{sub 4} (D is deuterium) single crystals.

  16. Sub-Saharan Africa

    African Journals Online (AJOL)

    Sub-Saharan Africa. Inbound tourism movement has emerged as an important factor in the preva- lence of the disease, after education. Defects of quality of data would not be far fetched, given the lack of logistics and financial resources of most governments for the exercise, possible political manipulations and ideological ...

  17. Magnetoelastic behaviour of Gd sub 5 Ge sub 4

    CERN Document Server

    Magen, C; Algarabel, P A; Marquina, C; Ibarra, M R

    2003-01-01

    A complete investigation of the complex magnetic behaviour of Gd sub 5 Ge sub 4 by means of linear thermal expansion and magnetostriction measurements (5-300 K, 0-120 kOe) has been carried out. Our results support the suggested existence in this system of a coupled crystallographic-magnetic transition from a Gd sub 5 Ge sub 4 -type Pnma (antiferromagnetic) to a Gd sub 5 Si sub 4 -type Pnma (ferromagnetic) state. Strong magnetoelastic effects are observed at the field-induced first-order magnetic-martensitic transformation. A revised magnetic and crystallographic H- T phase diagram is proposed.

  18. Foamed Cement Interactions with CO<sub>2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Verba, Circe [National Energy Technology Lab. (NETL), Albany, OR (United States); Montross, Scott [National Energy Technology Lab. (NETL), Albany, OR (United States); Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); Spaulding, Richard [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Dalton, Laura [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Morgantown, WV (United States); Crandall, Dustin [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Moore, Johnathan [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Glosser, Deborah [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Huerta, Nik [National Energy Technology Lab. (NETL), Albany, OR (United States); Kutchko, Barb [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2017-02-02

    Geologic carbon storage (GCS) is a potentially viable strategy to reduce greenhouse emissions. Understanding the risks to engineered and geologic structures associated with GCS is an important first step towards developing practices for safe and effective storage. The widespread utilization of foamed cement in wells may mean that carbon dioxide (CO<sub>2sub>)/brine/foamed cement reactions may occur within these GCS sites. Characterizing the difference in alteration rates as well as the physical and mechanical impact of CO<sub>2sub>/brine/foamed cement is an important preliminary step to ensuring offshore and onshore GCS is a prudent anthropogenic CO<sub>2sub> mitigation choice.

  19. Triangular Zn{sub 3} and Ga{sub 3} units in Sr{sub 2}Au{sub 6}Zn{sub 3}, Eu{sub 2}Au{sub 6}Zn{sub 3}, Sr{sub 2}Au{sub 6}Ga{sub 3}, and Eu{sub 2}Au{sub 6}Ga{sub 3}. Structure, magnetism, {sup 151}Eu Moessbauer and {sup 69;71}Ga solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gerke, Birgit; Niehaus, Oliver; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Korthaus, Alexander; Haarmann, Frank [RWTH Aachen Univ. (Germany). Inst. fuer Anorganische Chemie

    2016-08-01

    The gold-rich intermetallic compounds Sr{sub 2}Au{sub 6}Zn{sub 3}, Eu{sub 2}Au{sub 6}Zn{sub 3}, Sr{sub 2}Au{sub 6}Ga{sub 3}, and Eu{sub 2}Au{sub 6}Ga{sub 3} were synthesized from the elements in sealed tantalum ampoules in induction or muffle furnaces. The europium compounds are reported for the first time and their structures were refined from single crystal X-ray diffractometer data: Sr{sub 2}Au{sub 6}Zn{sub 3} type, R anti 3c, a = 837.7(1), c = 2184.5(4) pm, wR2 = 0.0293, 572 F{sup 2} values for Eu{sub 2}Au{sub 6.04}Zn{sub 2.96} and a = 838.1(2), c = 2191.7(5) pm, wR2 = 0.0443, 513 F{sup 2} values for Eu{sub 2}Au{sub 6.07}Ga{sub 2.93} with 20 variables per refinement. The structures consist of a three-dimensional gold network with a 6R stacking sequence, similar to the respective diamond polytype. The cavities of the network are filled in a ratio of 2:1 by strontium (europium) atoms and Ga{sub 3} (Zn{sub 3}) triangles in an ordered manner. Sr{sub 2}Au{sub 6}Zn{sub 3} and Sr{sub 2}Au{sub 6}Ga{sub 3} are diamagnetic with room temperature susceptibilities of -3.5 x 10{sup -4} emu mol{sup -1}. Temperature dependent susceptibility and {sup 151}Eu Moessbauer spectroscopic measurements show a stable divalent ground state for both europium compounds. Eu{sub 2}Au{sub 6}Zn{sub 3} and Eu{sub 2}Au{sub 6}Ga{sub 3} order antiferromagnetically below Neel temperatures of 16.3 and 12.1 K, respectively. Anisotropic electrical conductivity of Sr{sub 2}Au{sub 6}Ga{sub 3} is proven by an alignment of the crystallites in the magnetic field. Orientation-dependent {sup 69;71}Ga NMR experiments combined with quantum mechanical calculations (QM) give evidence for a highly anisotropic charge distribution of the Ga atoms.

  20. Structural and physical properties in the system ZnO-B{sub 2}O{sub 3}-P{sub 2}O{sub 5}-R{sub n}O{sub m}

    Energy Technology Data Exchange (ETDEWEB)

    Li Shengchun [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Chen Pei, E-mail: chenpei@dhu.edu.c [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Shanghai 201620 (China); Li Yaogang, E-mail: yaogang_li@dhu.edu.c [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China)

    2010-12-01

    The glass forming region in the quaternary system ZnO-B{sub 2}O{sub 3}-P{sub 2}O{sub 5}-R{sub n}O{sub m} has been determined. Glass transition temperature (T{sub g}), glass density ({rho}), thermal expansion coefficient ({alpha}) and weight loss percentage (W{sub L}) of these glasses were measured. The structure of (90-x-y)ZnO-xB{sub 2}O{sub 3}-yP{sub 2}O{sub 5}-10R{sub n}O{sub m} glass was characterized by infrared spectra (IR), Raman spectra and X-ray diffraction (XRD). Results of IR and Raman indicated that B{sub 2}O{sub 3} participated in the glass network as a glass modifier and the IR band around 1440 cm{sup -1} was ascribed to the v{sub as}(B-O-B) vibrations. Glass intensity increased with increase in B{sub 2}O{sub 3} content. The disappearance of v{sub s}(P-O-P) vibration around 760 cm{sup -1} indicated that P-O-B linkage was formed. XRD results revealed that the major crystalline phase changes with substitution of different amounts of B{sub 2}O{sub 3}: Zn{sub 2}P{sub 2}O{sub 7} for 45ZnO-xB{sub 2}O{sub 3}-35P{sub 2}O{sub 5}-10R{sub n}O{sub m} glass, where x=0-20, and BPO{sub 4} for 45ZnO-xB{sub 2}O{sub 3}-35P{sub 2}O{sub 5}-10R{sub n}O{sub m} glass, where x=30-40.

  1. Synthesis, structure and spectroscopic investigations of two new organic-inorganic hybrids NH{sub 3}(C{sub 6}H{sub 4}){sub 2}NH{sub 3}CuCl{sub 4} and NH{sub 3}(C{sub 6}H{sub 4}){sub 2}NH{sub 3}HgCl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Belhouchet, M; Wamani, W; Mhiri, T, E-mail: belhouchet2002@yahoo.fr [Laboratoire de l' Etat Solide, Departement de Chimie, Faculte des Sciences de Sfax, B. P.1171, 3000 Sfax (Tunisia)

    2010-11-15

    Two metal organic-inorganic hybrid compounds, NH{sub 3}(C{sub 6}H{sub 4}){sub 2}NH{sub 3}CuCl{sub 4}, 1, and NH{sub 3}(C{sub 6}H{sub 4}){sub 2}NH{sub 3}HgCl{sub 4}, 2, have been synthesized and structurally characterized by single-crystal X-ray diffraction. The two compounds crystallize in the monoclinic space groups P2{sub 1}/c and C2/c, respectively, with a = 14.3774 (7), b = 7.3472 (4), c = 7.1669 (3), {beta} = 96.589 (3){sup 0}, Z = 2 and R1 = 0.037 for 1, and a = 6.2986 (4), b = 18.2911 (12), c = 28.5854 (17), {beta} = 91.836 (2){sup 0}, Z = 8 and R1 = 0.049 for 2. The organic-inorganic layered perovskite structure of compound 1 features well-ordered sheets of corner-sharing distorted CuCl{sub 6} octahedra, due to the presence of Jahn-Teller effect in the d{sup 9} electronic system of Cu(II), separated by layers of benzidinium cations. The structure of compound 2 consists of anionic parallel layers built up from discrete tetrahedral HgCl{sub 4}{sup 2}- species, alternating with layers of organic molecules [NH{sub 3}(C{sub 6}H{sub 4}){sub 2}NH{sub 3}]{sup 2+}. The structures of the two compounds are stabilized by an extensive network of N-H...C1 hydrogen bonds. These compounds are also investigated by IR spectroscopy.

  2. The effect of Ca doping on the superconductivity of (R sub 0 sub . sub 4 Pr sub 0 sub . sub 6)Ba sub 2 Cu sub 3 O sub 7 sub - subdelta compounds prepared at high pressure (R = La, Pr, Nd, Sm, Eu, Gd and Y)

    CERN Document Server

    Yao Yu Shu; Che Guang Can; Ni Yong Ming; Liu Zhen Xing; Jia Shun Lian; Dong Cheng; Zhao Zhong Xian

    2002-01-01

    The nearly single phase (R sub 0 sub . sub 4 Pr sub 0 sub . sub 6) sub 0 sub . sub 5 Ca sub 0 sub . sub 5 Ba sub 2 Cu sub 3 O sub 7 sub - subdelta (R = La, Pr, Nd, Sm, Eu, Gd and Y) superconducting compounds should be prepared at high temperature and high pressure. The critical temperature of these compounds is over 100 K which is much higher than that of the traditional R-123 superconductors which do not have Ca doping on the rare-earth site. Our results shows that Pr behaves in the same way as other rare-earths in the 123-phase compounds due to the doping with Ca ions.

  3. Magnetic ordering in single crystals of PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta

    CERN Document Server

    Uma, S; Gmelin, E; Rangarajan, G; Skanthakumar, S; Lynn, J W; Walter, R; Lorenz, T; Büchner, B; Walker, E; Erb, A

    1998-01-01

    Heat capacity measurements on pure but twinned single crystals of PrBa sub 2 Cu sub 3 O sub 7 sub - subdelta reveal a sharp peak at T sub N sup P sup sub T =16.6 K, which according to thermal expansion, neutron diffraction, and magnetic susceptibility measurements originates from an antiferromagnetic ordering of the Pr-ion moments. A modest coupling to the Cu(2) spin system is observed. Below T sub N sup P sup sub T a first-order transition in the magnetic structure of the Pr spin system (at 13.4 K in warming; approx. 11 K in cooling) is found. Field-dependent heat capacity data show anisotropic temperature dependences of the c sub p -peaks and recover a Schottky-like anomaly due to the crystal-field-split ground state of the Pr sup 3 sup +. (author). Letter-to-the-editor

  4. A [Mo{sub 2}O{sub 2}S{sub 2}]-based ring system incorporating tartrate as the bridging ligand. Synthesis, structure and catalytic activity of Cs{sub 4}[Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sub 2}(μ{sub 4}-tart){sub 2} (tart=[C{sub 4}H{sub 2}O{sub 6}]{sup 4-})

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Ting-Ting; Cui, Yu-Jie; Xin, Zhifeng; Jia, Ai-Quan; Zhang, Qian-Feng [Anhui Univ. of Technology, Anhui (China). Inst. of Molecular Engineering and Applied Chemistry and Anhui Province Key Lab. of Metallurgy Engineering and Resources Recycling

    2017-08-01

    Treatment of [Mo{sub 2}S{sub 2}O{sub 2}(H{sub 2}O){sub 6}]{sup 2+} with racemic tartaric acid (tartH{sub 4}) in the presence of sodium hydroxide and cesium chloride in aqueous solution led to the isolation of a new tetra-molybdenum ring cluster Cs{sub 4}[Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sub 2}(μ{sub 4}-tart){sub 2}. The cyclic cluster polyanion consists of two dinuclear [Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sup 2+} moieties and two bridging tart{sup 4-} ligands. The cyclic polyoxothiomolybdate cluster, supported on the mesoporous silica SBA-15, was tested for heterogenerous catalysis in thiophene hydrodesulfurization.

  5. Single-Site Cobalt Catalysts at New Zr <sub>8sub> (μ <sub>2sub> -O) <sub>8sub> (μ <sub>2sub> -OH) <sub>4sub> Metal-Organic Framework Nodes for Highly Active Hydrogenation of Alkenes, Imines, Carbonyls, and Heterocycles

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Pengfei; Manna, Kuntal; Lin, Zekai; Urban, Ania; Greene, Francis X.; Lan, Guangxu; Lin, Wenbin

    2016-09-21

    We report here the synthesis of robust and porous metal–organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis(p-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M<sub>8sub>(μ>2sub>-O)>8sub>(μ>2sub>-OH)>4sub> and octahedral M6(μ<sub>3sub>-O)>4sub>(μ>3sub>-OH)>4sub>. While the M<sub>6sub>-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M<sub>8sub>-SBU is composed of eight MIV ions in a cubic fashion linked by eight μ<sub>2sub>-oxo and four μ<sub>2sub>-OH groups. The metalation of Zr-MTBC SBUs with CoCl<sub>2sub>, followed by treatment with NaBEt<sub>3sub>H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr<sub>8sub>-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis.

  6. Vanishing of T sub c and appearance of quantum paraelectricity in KD sub 2 PO sub 4 and KH sub 2 PO sub 4 under high pressure

    CERN Document Server

    Endo, S; Tokunaga, M

    2002-01-01

    The temperature dependences of the dielectric constants of the hydrogen-bond ferroelectrics KH sub 2 PO sub 4 (KDP) and KD sub 2 PO sub 4 (DKDP) were measured under high hydrostatic pressure. Their ferroelectric transition temperatures T sub c monotonically decreased with increasing pressure and the ferroelectric state vanished at p sub c : 1.7 GPa for KDP and 6.1 GPa for DKDP. On the other hand, the Curie constant remained finite at p sub c , which indicates that the ferroelectric phase transition at high pressure is of displacive type. At pressures around p sub c , quantum paraelectricity was observed in KDP and DKDP.

  7. Structure, synthesis, and thermal properties of trans-[Ru(NO)(NH{sub 3}){sub 4}(SO{sub 4})]NO{sub 3}.H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Makhinya, A.N.; Il' in, M.A.; Plyusnin, P.E. [Russian Academy of Sciences, Novosibirsk (Russian Federation). Nikolaev Inst. of Inorganic Chemistry; Novosibirsk State Univ. (Russian Federation); Baidina, I.A.; Alferova, N.I.; Pishchur, D.P. [Russian Academy of Sciences, Novosibirsk (Russian Federation). Nikolaev Inst. of Inorganic Chemistry

    2014-07-01

    In treatment of trans-[Ru(NO)(NH{sub 3}){sub 4}(OH)]Cl{sub 2} with concentrated sulfuric acid on heating trans-[Ru(NO)(NH{sub 3}){sub 4}(SO{sub 4})](HSO{sub 4}).H{sub 2}O (I) is obtained with a yield close to quantitative. In the interaction of the saturated solution of I with a saturated NaNO{sub 3} solution a trans-[Ru(NO)(NH{sub 3}){sub 4}(SO{sub 4})]NO{sub 3}.H{sub 2}O (II) precipitate forms whose structure is determined by single crystal XRD: space group P2{sub 1}2{sub 1}2{sub 1}, a = 6.8406(3) Aa, b = 12.6581(5) Aa, c = 13.3291(5) Aa. A monodentately coordinated sulfate ion is in the trans-position to the nitroso group. Compound II is characterized by IR spectroscopy, powder XRD, and diffuse reflectance spectroscopy. The process of its thermolysis is studied; by differential scanning calorimetry the thermal effect of the dehydration reaction occurring on heating to 120 C (ΔH = 58.9 ± 1.5 kJ/mol) is estimated. The final product of the thermolysis of II is a mixture of Ru and RuO{sub 2}.

  8. Selective Metal Exsolution in BaFe<sub>2-ysub>My(PO>4sub>)>2 sub>(M = Co2+, Ni2+) Solid Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Alcover, Ignacio Blazquez [Universite Lille Nord de France (France); Daviero-Minaud, Sylvie [Universite Lille Nord de France (France); David, Rénald [Universite Picardie Jules Verne (France); Filimonov, Dmitry [Moscow State Univ., Moscow (Russian Federation); Huvé, Marielle [Universite Lille Nord de France (France); Attfield, J. Paul [Univ. of Edinburgh (United Kingdom); Kabbour, Houria [Universite Lille Nord de France (France); Mentré, Olivier [Universite Lille Nord de France (France)

    2015-08-19

    The 2D-Ising ferromagnetic phase BaFe2+<sub>2sub>(PO>4sub>)>2sub> shows exsolution of up to one-third of its iron content (giving BaFe3+<sub>1.33sub>(PO>4sub>)>2sub>) under mild oxidation conditions, leading to nanosized Fe<sub>2sub>O>3sub> exsolved clusters. Here we have prepared BaFe<sub>2–ysub>My(PO>4sub>)>2sub> (M = Co2+, Ni2+; y = 0, 0.5, 1, 1.5) solid solutions to investigate the feasibility and selectivity of metal exsolution in these mixed metallic systems. For all the compounds, after 600 °C thermal treatment in air, a complete oxidation of Fe2+ to Fe3+ leaves stable M2+ ions, as verified by 57Fe Mössbauer spectroscopy, TGA, TEM, microprobe, and XANES. Furthermore, the size of the nanometric α-Fe<sub>2sub>O>3sub>clusters coating the main phase strongly depends on the y<sub>M> metal concentration. For M-rich phases the iron diffusion is hampered so that a significant fraction of superparamagnetic α-Fe2O3 particles (100% for BaFe<sub>0.5–xsub>Co>1.5sub>(PO>4sub>)>2sub>) was detected even at 78 K. Although Ni2+and Co2+ ions tend to block Fe diffusion, the crystal structure of BaFe<sub>0.67sub>Co>1sub>(PO>4sub>)>2sub>demonstrates a fully ordered rearrangement of Fe3+ and Co2+ ions after Fe exsolution. We found that the magnetic behaviors of the Fe-depleted materials are mostly dominated by antiferromagnetic exchange, while Co2+-rich compounds show metamagnetic transitions reminiscent of the BaCo<sub>2sub>(PO>4sub>)>2sub> soft helicoidal magnet.

  9. Modifications of structural and physical properties induced by swift heavy ions in Gd{sub 2}Ti{sub 2}O{sub 7} and Y{sub 2}Ti{sub 2}O{sub 7} pyrochlores

    Energy Technology Data Exchange (ETDEWEB)

    Sellami, N., E-mail: neila.sellami@u-psud.fr [Univ. Paris Sud, ICMMO-LEMHE, Bât. 410, F-91405 Orsay (France); Sattonnay, G. [Univ. Paris Sud, ICMMO-LEMHE, Bât. 410, F-91405 Orsay (France); Grygiel, C.; Monnet, I. [CIMAP, CEA, CNRS, Université de Caen, BP 5133, F-14070 Caen Cedex 5 (France); Debelle, A. [CSNSM, CNRS, IN2P3, Université Paris-Sud, Bât. 108, F- 91405 Orsay (France); Legros, C. [Univ. Paris Sud, ICMMO-LEMHE, Bât. 410, F-91405 Orsay (France); Menut, D. [CEA, DEN, Service de Recherches Métallurgiques Appliquées, 91191 Gif-Sur-Yvette (France); Miro, S. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Simon, P. [CNRS UPR 3079 CEMHTI, 1D avenue de la Recherche Scientifique, F-45071 Orléans Cedex 2 (France); Bechade, J.L [CEA, DEN, Service de Recherches Métallurgiques Appliquées, 91191 Gif-Sur-Yvette (France); Thomé, L. [CSNSM, CNRS, IN2P3, Université Paris-Sud, Bât. 108, F- 91405 Orsay (France)

    2015-12-15

    The structural transformations induced by ionization processes in Gd{sub 2}Ti{sub 2}O{sub 7} and Y{sub 2}Ti{sub 2}O{sub 7} pyrochlores irradiated with swift heavy ions have been studied using XRD and Raman experiments. Results show that irradiation induces amorphization and that the phase transformation build-up can be accounted for in the framework of a model involving a single-impact mechanism. The radiation induced amorphization build-up is faster in Gd{sub 2}Ti{sub 2}O{sub 7} than in Y{sub 2}Ti{sub 2}O{sub 7}. Moreover, a decrease of the thermal conductivity (measured by the laser flash method) is induced by irradiation both in Gd{sub 2}Ti{sub 2}O{sub 7} and Y{sub 2}Ti{sub 2}O{sub 7}.

  10. High temperature redox reactions with uranium: Synthesis and characterization of Cs(UO{sub 2})Cl(SeO{sub 3}), Rb{sub 2}(UO{sub 2}){sub 3}O{sub 2}(SeO{sub 3}){sub 2}, and RbNa{sub 5}U{sub 2}(SO{sub 4}){sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Babo, Jean-Marie [Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306-4390 (United States); Department of Civil and Environmental Engineering and Earth Sciences and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556 (United States); Albrecht-Schmitt, Thomas E., E-mail: talbrechtschmitt@gmail.com [Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306-4390 (United States)

    2013-10-15

    Cs(UO{sub 2})Cl(SeO{sub 3}) (1), Rb{sub 2}(UO{sub 2}){sub 3}O{sub 2}(SeO{sub 3}){sub 3} (2), and RbNa{sub 5}U{sub 2}(SO{sub 4}){sub 7} (3) single crystals were synthesized using CsCl, RbCl, and a CuCl/NaCl eutectic mixture as fluxes, respectively. Their lattice parameters and space groups are as follows: P2{sub 1}/n (a=6.548(1) Å, b=11.052(2) Å, c=10.666(2) Å and β=93.897(3)°), P1{sup ¯} (a=7.051(2) Å, b=7.198(2) Å, c=8.314(2) Å, α=107.897(3)°, β=102.687(3)° and γ=100.564(3)°) and C2/c (a=17.862(4) Å, b=6.931(1) Å, c=20.133(4) Å and β=109.737(6)°. The small anionic building units found in these compounds are SeO{sub 3}{sup 2−} and SO{sub 4}{sup 2−} tetrahedra, oxide, and chloride. The crystal structure of the first compound is composed of [(UO{sub 2}){sub 2}Cl{sub 2}(SeO{sub 3}){sub 2}]{sup 2−} chains separated by Cs{sup +} cations. The structure of (2) is constructed from [(UO{sub 2}){sub 3}O{sub 11}]{sup 16−} chains further connected through selenite units into layers stacked perpendicularly to the [0 1 0] direction, with Rb{sup +} cations intercalating between them. The structure of compound (3) is made of uranyl sulfate layers formed by edge and vertex connections between dimeric [U{sub 2}O{sub 16}] and [SO{sub 4}] polyhedra. These layers contain unusual sulfate–metal connectivity as well as large voids. - Graphical abstract: A new family of uranyl selenites and sulfates has been prepared by high-temperature redox reactions. This compounds display new bonding motifs. Display Omitted - Highlights: • Low-dimensional Uranyl Oxoanion compounds. • Conversion of U(IV) to U(VI) at high temperatures. • Dimensional reduction by both halides and stereochemically active lone-pairs.

  11. Magnetic sublattices in Np{sub 2}Co{sub 17} and Np{sub 2}Ni{sub 17}

    Energy Technology Data Exchange (ETDEWEB)

    Colineau, E., E-mail: eric.colineau@ec.europa.eu; Hen, A. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Sanchez, J.-P. [CEA, INAC-SPSMS (France); Griveau, J.-C.; Magnani, N.; Eloirdi, R. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Halevy, I. [Ben Gurion University, Nuclear Engineering Department (Israel); Gaczyński, P. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Orion, I. [Ben Gurion University, Nuclear Engineering Department (Israel); Shick, A. B. [Institute of Physics, ASCR (Czech Republic); Caciuffo, R. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany)

    2016-12-15

    Rare-earth-based compounds R{sub 2}T{sub 17} (R=Rare earth; T=Transition metal) have been extensively studied and developed for applications as permanent magnets. The actinide-based analogues, however, are much less documented and we report here about the magnetic properties of Np{sub 2}Co{sub 17} and Np{sub 2}Ni{sub 17}, as inferred from {sup 237}Np Mössbauer spectroscopy, the best resonance in actinides, and specific heat.

  12. Anion- or Cation-Exchange Membranes for NaBH<sub>4sub>/H>2sub>O>2 sub>Fuel Cells?

    Directory of Open Access Journals (Sweden)

    César A. C. Sequeira

    2012-07-01

    Full Text Available Direct borohydride fuel cells (DBFC, which operate on sodium borohydride (NaBH<sub>4sub> as the fuel, and hydrogen peroxide (H<sub>2sub>O>2sub> as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH<sub>4sub>/H>2sub>O>2sub> fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S and a cation-exchange membrane (CMI-7000S, are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  13. Persistence of slow fluctuations in the overdoped regime of Ba(Fe<sub>1-xsub>Rhx)>2sub>As>2sub> superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bossoni, L. [Univ. of Pavia (Italy); Leiden Univ. (Netherlands); Moroni, M. [Univ. of Pavia (Italy); Julien, M. H. [Leiden Univ. (Netherlands); Canfield, Paul C. [Ames Lab. and Iowa State Univ., Ames, IA (United States); Mayaffre, H. [Leiden Univ. (Netherlands); Reyes, A. [National High Magnetic Field Lab., Tallahassee, FL (United States); Halperin, W. P. [Northwestern Univ., Evanston, IL (United States); Carretta, P. [Univ. of Pavia (Italy)

    2016-04-15

    We present nuclear magnetic resonance evidence that very slow (1 MHz) spin fluctuations persist into the overdoped regime of Ba(Fe<sub>1-xsub>Rhx)>2sub>As>2sub> superconductors. Measurements of the 75As spin echo decay rate, obtained both with Hahn Echo and Carr Purcell Meiboom Gill pulse sequences, show that the slowing down of spin uctuations can be described by short-range diffusive dynamics, likely involving domain walls motions separating (π/a, 0) from (0, π/a) correlated regions. This slowing down of the fluctuations is weakly sensitive to the external magnetic field and, although fading away with doping, it extends deeply into the overdoped regime.

  14. Searching for θ<sub>13sub> at Daya Bay

    Energy Technology Data Exchange (ETDEWEB)

    Giedt, Joel [Rensselaer Polytechnic Inst., Troy, NY (United States); Napolitano, James [Temple Univ., Philadelphia, PA (United States)

    2015-06-08

    An experiment has been carried out by the Daya Bay Collaboration to measure the neutrino mixing angle θ<sub>13sub>. In addition, the grant has supported research into lattice field theory beyond the standard model.

  15. Phase evolution and its effect on magnetic properties of Nd sub 6 sub 0 Al sub 1 sub 0 Fe sub 2 sub 0 Co sub 1 sub 0 bulk metallic glass

    CERN Document Server

    Lei Xia; Pan, M X; Zhao, D Q; Wang, W H; Dong, Y D

    2003-01-01

    The thermal stability of nanocrystalline clusters, the phase evolution, and their effects on magnetic properties were studied for as-cast Nd sub 6 sub 0 Al sub 1 sub 0 Fe sub 2 sub 0 Co sub 1 sub 0 alloy using differential scanning calorimetry curves, x-ray diffraction patterns, scanning electron microscopy, and high-resolution transition electron microscopy. Thermomagnetic curves and hysteresis loops of the bulk metallic glass were measured during the annealing process. The high thermostability of the hard magnetic properties of the samples observed is attributed to the stability of the nanocrystalline clusters upon annealing, while the slight enhancement in the magnetization is due to the precipitation of some Nd-rich metastable phases. The mechanism of thermostability of the nanocrystalline clusters and the formation of the metastable phases are discussed.

  16. Structure and properties of ZnO-B{sub 2}O{sub 3}-P{sub 2}O{sub 5}-TeO{sub 2} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Mosner, Petr, E-mail: petr.mosner@upce.cz [Department of General and Inorganic Chemistry, University of Pardubice, Faculty of Chemical Technology, 53210 Pardubice (Czech Republic); Vosejpkova, Katerina; Koudelka, Ladislav [Department of General and Inorganic Chemistry, University of Pardubice, Faculty of Chemical Technology, 53210 Pardubice (Czech Republic); Montagne, Lionel; Revel, Bertrand [Unite de Catalyse et de Chimie du Solide - UCCS, Univ Lille Nord de France, F-59000, CNRS UMR 8181, USTL F-59655, ENSCL F-59652, Villeneuve d' Ascq (France)

    2010-11-01

    Zinc borophosphate glasses doped with TeO{sub 2} were studied in the compositional series (100 - x)[0.5ZnO-0.1B{sub 2}O{sub 3}-0.4P{sub 2}O{sub 5}]-xTeO{sub 2} in a broad concentration range of x = 0-80 mol% TeO{sub 2}. The structure of the glasses was studied by Raman and IR spectroscopy and by {sup 31}P and {sup 11}B MAS NMR spectroscopy. According to the Raman and IR spectra, TeO{sub 2} is incorporated in the structural network in the form of TeO{sub 3}, TeO{sub 3+1} and TeO{sub 4} structural units. The ratio of TeO{sub 4}/TeO{sub 3} increases with increasing TeO{sub 2} content in the glasses. The incorporation of TeO{sub x} units into the glass network is associated with the depolymerisation of phosphate chains, as revealed by Raman spectroscopy. The incorporation of TeO{sub 2} modifies also the coordination of boron atoms, where B(OP){sub 4} structural units are gradually replaced by B(OP){sub 4-n}(OTe){sub n} units. The addition of TeO{sub 2} to the parent zinc borophosphate glass results in a decrease of glass transition temperature associated with the replacement of stronger P-O and B-O bonds by weaker Te-O bonds. Chemical durability of glasses reveals a minimum at the glass containing 10 mol% TeO{sub 2}, but with further additions of TeO{sub 2} it improves and the glasses with a high TeO{sub 2} content reveal better durability than the parent zinc borophosphate glass.

  17. Microbial Growth under Supercritical CO <sub>2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Peet, Kyle C.; Freedman, Adam J. E.; Hernandez, Hector H.; Britto, Vanya; Boreham, Chris; Ajo-Franklin, Jonathan B.; Thompson, Janelle R.; Nojiri, H.

    2015-02-13

    Growth of microorganisms in environments containing CO<sub>2sub>above its critical point is unexpected due to a combination of deleterious effects, including cytoplasmic acidification and membrane destabilization. Thus, supercritical CO<sub>2sub>(scCO>2sub>) is generally regarded as a sterilizing agent. We report isolation of bacteria from three sites targeted for geologic carbon dioxide sequestration (GCS) that are capable of growth in pressurized bioreactors containing scCO<sub>2sub>. Analysis of 16S rRNA genes from scCO<sub>2sub>enrichment cultures revealed microbial assemblages of varied complexity, including representatives of the genusBacillus. Propagation of enrichment cultures under scCO<sub>2sub>headspace led to isolation of six strains corresponding toBacillus cereus,Bacillus subterraneus,Bacillus amyloliquefaciens,Bacillus safensis, andBacillus megaterium. Isolates are spore-forming, facultative anaerobes and capable of germination and growth under an scCO<sub>2sub>headspace. In addition to these isolates, severalBacillustype strains grew under scCO<sub>2sub>, suggesting that this may be a shared feature of spore-formingBacillusspp. Our results provide direct evidence of microbial activity at the interface between scCO<sub>2sub>and an aqueous phase. Since microbial activity can influence the key mechanisms for permanent storage of sequestered CO<sub>2sub>(i.e., structural

  18. Synthesis of spinel Li{sub 4}Ti{sub 5}O{sub 12}–ramsdellite Li{sub 2}Ti{sub 3}O{sub 7} composites under vacuum and their electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Xiangkun [State Key Laboratory of Clear Utilization of Complex Nonferrous Metal Resources in Yunnan Province, Kunming University of Science and Technology, Kunming 650093 (China); National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093 (China); Yang, Guiling, E-mail: yanggl429@gmail.com [State Key Laboratory of Clear Utilization of Complex Nonferrous Metal Resources in Yunnan Province, Kunming University of Science and Technology, Kunming 650093 (China); National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093 (China); Yao, Yaochun [State Key Laboratory of Clear Utilization of Complex Nonferrous Metal Resources in Yunnan Province, Kunming University of Science and Technology, Kunming 650093 (China); National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093 (China); Dai, Yongnian [National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093 (China)

    2015-07-15

    Highlights: • Li{sub 4}Ti{sub 5}O{sub 12}–Li{sub 2}Ti{sub 3}O{sub 7} composites are prepared under vacuum. • Citric acid existence will decrease the composite forming temperature. • The reaction mechanism is discussed. • The charge/discharge curve of Li{sub 4}Ti{sub 5}O{sub 12} is modified in the presence of Li{sub 2}Ti{sub 3}O{sub 7}. - Abstract: Composites of spinel Li{sub 4}Ti{sub 5}O{sub 12}–ramsdellite Li{sub 2}Ti{sub 3}O{sub 7} (Li{sub 4}Ti{sub 5}O{sub 12}–Li{sub 2}Ti{sub 3}O{sub 7}) were prepared and evaluated for anode materials in lithium-ion batteries. Our experimental results turns out that sintering temperatures and carbon content play important roles in forming these composites. Under vacuum, it is found that Li{sub 4}Ti{sub 5}O{sub 12}–Li{sub 2}Ti{sub 3}O{sub 7} composites can be synthesized at around 600 °C under the help of citric acid. According to the XRD patterns, its reaction mechanism is suggested in this study. In addition, electrochemical testing demonstrates that the presence of Li{sub 2}Ti{sub 3}O{sub 7} in the prepared sample modifies the charge/discharge behavior of Li{sub 4}Ti{sub 5}O{sub 12}, which makes it easily to monitor its SOC/SOD according to its voltage profile.

  19. Solubilities of CO sub 2 and redox equilibria of Sb and As in Na sub 2 O-Sb sub 2 O sub m and Na sub 2 O-As sub 2 O sub m melts. Na sub 2 O Sb sub 2 O sub m , Na sub 2 O-As sub 2 O sub m kei yoyu slag no CO sub 2 yokairyo to Sb to As no fuzon jotai

    Energy Technology Data Exchange (ETDEWEB)

    Fukuyama, H. (Nagoya Univ., Nagoya (Japan). Graduate School); Katao, T. (Sumitomo Metal Industries Ltd., Osaka (Japan)); Ikitsu, Y. (Daido Steel Co. Ltd., Nagoya (Japan)); Fujisawa, T.; Yamauchi, C. (Nagoya Univ., Nagoya (Japan). Faculty of Engineering)

    1991-12-20

    Solubilities of CO{sub 2} in Na{sub 2}O-Sb{sub 2}O{sub m} and Na{sub 2}O-As{sub 2}O{sub m} melts and redox ratio of Sb and As melts are measured over the composition range of 1>N>0.7 under the partial pressures of CO{sub 2} and 0{sub 2} from 0.01 to 0.1MPa and from 0.005 to 1000Pa, respectively, at the temperature of 1423 and 1523K. Based on the result of the measurement, reaction equation is studied which governs the redox equilibria of Sb and As and the solubilities of CO{sub 2} in those melts. Sb in Na{sub 2}O-CO{sub 2}-Sb{sub 2}O{sub m} melts exists in pentavalent and trivalent states. In Na{sub 2}O- CO{sub 2}-As{sub 2}O{sub m} melts, pentavalent As is very stable in comparison to Sb, and most of As exists in the state of complex ion. However, with the increase in the content of As{sub 2}O{sub 5} in the melts, the evaporation reaction of trivalent As becomes significant. 6 refs., 11 figs., tab.

  20. Selection of Nuclear Fuel for TREAT: UO<sub>2sub> vs U<sub>3sub>O>8sub>

    Energy Technology Data Exchange (ETDEWEB)

    Glazoff, Michael Vasily [Idaho National Lab. (INL), Idaho Falls, ID (United States); Van Rooyen, Isabella Johanna [Idaho National Lab. (INL), Idaho Falls, ID (United States); Coryell, Benjamin David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Parga, Clemente Jose [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-04-01

    The Transient Reactor Test (TREAT) that resides at the Materials and Fuels Complex (MFC) at Idaho National Laboratory (INL), first achieved criticality in 1959, and successfully performed many transient tests on nuclear fuel until 1994 when its operations were suspended. Resumption of operations at TREAT was approved in February 2014 to meet the U.S. Department of Energy (DOE) Office of Nuclear Energy’s objectives in transient testing of nuclear fuels. The National Nuclear Security Administration’s is converting TREAT from its existing highly enriched uranium (HEU) core to a new core containing low enriched uranium (LEU) (i.e., U-235< 20% by weight). The TREAT Conversion project is currently progressing with conceptual design phase activities. Dimensional stability of the fuel element assemblies, predictable fuel can oxidation and sufficient heat conductivity by the fuel blocks are some of the critical performance requirements of the new LEU fuel. Furthermore, to enable the design team to design fuel block and can specifications, it is amongst the objectives to evaluate TREAT LEU fuel and cladding material’s chemical interaction. This information is important to understand the viability of Zr-based alloys and fuel characteristics for the fabrication of the TREAT LEU fuel and cladding. Also, it is very important to make the right decision on what type of nuclear fuel will be used at TREAT. In particular, one has to consider different oxides of uranium, and most importantly, UO<sub>2sub> vs U<sub>3sub>O>8sub>. In this report, the results are documented pertaining to the choice mentioned above (UO<sub>2sub> vs U<sub>3sub>O>8sub>). The conclusion in favor of using UO<sub>2sub> was made based on the analysis of historical data, up-to-date literature, and self-consistent calculations of phase equilibria and thermodynamic properties in the U-O and U-O-C systems. The report is organized as follows. First, the criteria that were used to make the

  1. Asymmetric cation non-stoichiometry in spinels: site occupancy in Co<sub>2sub>ZnO>4sub> and Rh<sub>2sub>ZnO>4sub>

    Energy Technology Data Exchange (ETDEWEB)

    Paudel, Tula; Lany, Stephan; d' Avezac, Mayeul; Zunger, Alex; Perry, Nicola H.; Nagaraja, Arpun R.; Mason, Thomas O.; Bettinger, Joanna S.; Shi, Yezhou; Toney, Michael F.

    2011-01-01

    Two cations A and B in A₂BO₄ spinels appear in precise 2:1 Daltonian ratio ("line compounds") only at very low temperature. More typically, at finite temperature, they tend to become either A rich or B rich. Here we survey the experimentally observed stoichiometry asymmetries and describe the first-principles framework for calculating these. Defect calculations based on first principles are used to calculate the enthalpies of substitution of A atom ΔH(A<sub>Td>) and B atom ΔH(B<sub>Oh>) and determine their site occupancies leading to (non)-stoichiometry. In Co₂ZnO₄, the result of the calculation for site occupancy compares well with that measured via anomalous x-ray diffraction. Further, the calculated phase boundary also compares well with that measured via Rietveld refinement of x-ray diffraction data on bulk ceramic sintered samples of Co₂ZnO₄ and Rh₂ZnO₄. These results show that Co₂ZnO₄ is heavily Co nonstoichiometric above 500 °C, whereas Rh₂ZnO₄ is slightly Zn nonstoichiometric. We found that, in general, the calculated ΔH(A<sub>Td>) is smaller than ΔH(B<sub>Oh>), if the A-rich competing phase is isostructural with the A₂BO₄ host, for example, A₂AO₄, whereas B-rich competing phase is not, for example, BO. This observation is used to qualitatively explain nonstoichiometry and solid solutions observed in other spinels.

  2. Amorphous Al{sub 1-x}Ti{sub x}, Al{sub 1-x}V{sub x}, and Al{sub 1-x}Fe{sub x} phases in the hydrogen cycled TiCl{sub 3}, VCl{sub 3} and FeCl{sub 3} enhanced NaAlH{sub 4} systems

    Energy Technology Data Exchange (ETDEWEB)

    Pitt, M.P., E-mail: mark.pitt@gmail.com [Physics Department, Institute for Energy Technology, P.O. Box 40 Kjeller N-2027 (Norway); Department of Imaging and Applied Physics, Curtin University, GPO Box U1987, Perth 6845, Western Australia (Australia); Queensland Micro and Nanotechnology Centre, Griffith University, Brisbane 4111 (Australia); Vullum, P.E. [Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Sorby, M.H. [Physics Department, Institute for Energy Technology, P.O. Box 40 Kjeller N-2027 (Norway); Emerich, H. [Swiss-Norwegian Beam Line, European Synchrotron Radiation Facility, BP 220, Grenoble Cedex (France); Paskevicius, M.; Buckley, C.E. [Department of Imaging and Applied Physics, Curtin University, GPO Box U1987, Perth 6845, Western Australia (Australia); Gray, E. MacA. [Queensland Micro and Nanotechnology Centre, Griffith University, Brisbane 4111 (Australia); Walmsley, J.C. [Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); SINTEF, Materials and Chemistry, NO-7465 Trondheim (Norway); Holmestad, R. [Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Hauback, B.C. [Physics Department, Institute for Energy Technology, P.O. Box 40 Kjeller N-2027 (Norway)

    2012-04-25

    Highlights: Black-Right-Pointing-Pointer Quantification of amorphous Al{sub 1-x}TM{sub x} phases in H cycled TMCl{sub n} enhanced NaAlH{sub 4}. Black-Right-Pointing-Pointer Composite nano surface morphology between crystalline/amorphous Al{sub 1-x}TM{sub x}: TM = Ti, V. Black-Right-Pointing-Pointer All Fe atoms consumed within <15 nm thick amorphous Al{sub 1-x}Fe{sub x} on NaAlH{sub 4} surface. Black-Right-Pointing-Pointer Amorphous Al{sub 1-x}Ti{sub x} is Ti poor, <13.5 at.% Ti, amorphous Al{sub 1-x}V{sub x} reaches 28 at.% V. - Abstract: The twice hydrogen (H) cycled planetary milled (PM) and cryo milled (CM) NaAlH{sub 4} + xTMCl{sub 3} (transition metal (TM) = Ti, V, Fe) systems (x > 0.1) have been studied by high resolution synchrotron X-ray diffraction, and high resolution transmission electron microscopy (TEM). Intense primary amorphous (a-) Al{sub 1-x}TM{sub x} halos are evident in diffraction data of PM samples for V and Fe, and in CM samples for Ti, V, and Fe. Weaker primary amorphous Al{sub 1-x}Ti{sub x} halos are evident in PM samples for Ti. The Ti poor a-Al{sub 1-x}Ti{sub x} phase observed for NaAlH{sub 4} + xTiCl{sub 3} (x > 0.1) ranges in composition from a-Al{sub 86.5}Ti{sub 13.5} {yields} a-Al{sub 92}Ti{sub 8}. High resolution TEM studies of the Al{sub 1-x}V{sub x} phases in the H cycled PM NaAlH{sub 4} + 0.1VCl{sub 3} system demonstrates that a nanoscopic composite morphology can exist between face centred cubic (fcc) crystalline (c-) Al{sub 1-x}V{sub x} and a-Al{sub 1-x}V{sub x} phases, with the c-Al{sub 1-x}V{sub x}/a-Al{sub 1-x}V{sub x} composite embedded on the NaAlH{sub 4} surface. The amorphous Al{sub 1-x}V{sub x} reaches ca. 28 at.% V.

  3. High-pressure pyrolysis study of C sub 3 N sub 6 H sub 6 : a route to preparing bulk C sub 3 N sub 4

    CERN Document Server

    Ma, H A; Chen, L X; Zhu, P W; Guo, W L; Guo, X B; Wang, Y D; Li, S Q; Zou Guang Tian; Zhang, G; Bex, P

    2002-01-01

    In order to prepare bulk C sub 3 N sub 4 , high-pressure pyrolysis of melamine (C sub 3 N sub 6 H sub 6) at different temperatures was carried out. The products were characterized by C, N, H element analysis, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffractometry. The results of the analysis reveal that graphitic phase C sub 3 N sub 4 has been synthesized. It provides a novel route to synthesis of the theoretical superhard cubic C sub 3 N sub 4 and other C sub 3 N sub 4 phases from organic compounds by a high-pressure and high-temperature method.

  4. Synthesis and structural characterization of Li{sub 3}Y(BO{sub 3}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Braeuchle, Sebastian; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2017-03-01

    Li{sub 3}Y(BO{sub 3}){sub 2} was prepared by high-temperature solid state synthesis at 900 C in a platinum crucible from lithium carbonate, boric acid, and yttrium(III) oxide. The compound crystallizes monoclinically in the space group P2{sub 1}/c (no. 14) (Z=4) isotypically to Li{sub 3}Gd(BO{sub 3}){sub 2}. The structure was refined from single-crystal X-ray diffraction data: a=8.616(3), b=6.416(3), c=10.014(2) Aa, β=116.6(2) , V=494.9(3) Aa{sup 3}, R1=0.0211, and wR2=0.0378 for all data. The crystal structure of Li{sub 3}Y(BO{sub 3}){sub 2} consists of [Y{sub 2}O{sub 14}] dinuclear units, which are interconnected to each other by planar B(1)O{sub 3} groups and LiO{sub 4} tetrahedra via common edges and corners along the a axis.

  5. Hydrothermal synthesis and structural analysis of new mixed oxyanion borates: Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6}, Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) and Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16}

    Energy Technology Data Exchange (ETDEWEB)

    Heyward, Carla, E-mail: cheywar@clemson.edu; McMillen, Colin D., E-mail: cmcmill@clemson.edu; Kolis, Joseph, E-mail: kjoseph@clemson.edu

    2013-07-15

    Several new borate compounds, Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6} (1), Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) (2), and Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16} (3) were synthesized containing other hetero-oxyanion building blocks in addition to the borate frameworks. They were all prepared under hydrothermal conditions and characterized by single crystal and powder X-ray diffraction, and IR spectroscopy. Crystal data: For 1; space group P2{sub 1}/c, a=6.8909 (14) Å, b=13.629 (3) Å, c=25.851 (5) Å, β=90.04 (3)°; For 2; space group P-31c, a=8.8599 (13) Å, c=15.148 (3) Å; For 3; space group P-1, a=5.0414 (10) Å, b=7.5602 (15) Å, c=8.5374 (17) Å, α=77.15 (3)°, β=77.84 (3)°, γ=87.41 (3)° for 3. Compounds 1 and 2 contain isolated oxyanions [PO{sub 4}]{sup 3−} and [CO{sub 3}]{sup 2−} respectively, sitting in channels created by the borate framework, while structure 3 has the [SiO{sub 4}]{sup 4−} groups directly bonded to the borate groups creating a B–O–Si framework. - Highlights: • Hydrothermal syntheses of three new mixed oxyanion borates are presented. • Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6} contains isolated [PO{sub 4}]{sup 3−} in voids of the borate framework. • Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) contains isolated [CO{sub 3}]{sup 2−} in channels created by the framework. • Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16} has direct bonding of [SiO{sub 4}]{sup 4−} and borates creating a B–O–Si framework.

  6. Uranyl tris-(carbohydrazide) nitrate [UO{sub 2}((N{sub 2}H{sub 3}){sub 2}CO){sub 3}](NO{sub 3}){sub 2}. Synthesis, structure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Leshok, Darya Y.; Samoilo, Alexander A.; Kirik, Sergei D. [Siberian Federal Univ., Krasnoyarsk (Russian Federation); Alekseenko, Vladimir N. [Federal Centre for Nuclear and Radiation Safety, Moscow (Russian Federation); Gavrilov, Peter M.; Alekseenko, Sergei N.; Dyachenko, Anton S. [Mining and Chemical Combine, Zheleznogorsk, Krasnoyarskii region (Russian Federation); Kondrasenko, Alexander A. [NMR Facility at Krasnoyarsk Multiaccesed Centre SB RAN, Krasnoyarsk (Russian Federation)

    2015-07-01

    Uranyl tris-(carbohydrazide) nitrate [UO{sub 2}((N{sub 2}H{sub 3}){sub 2}CO){sub 3}](NO{sub 3}){sub 2} was prepared by the reaction of water solution of dioxouranium(VI) nitrate UO{sub 2}(NO{sub 3}){sub 2}(H{sub 2}O){sub 6} with ethanol solution of carbohydrazide (N{sub 2}H{sub 3}){sub 2}CO in a molar ratio of 1 to 3 in an neutral medium. The substance was characterized by elemental, thermal analysis and IR and {sup 15}N MAS CP NMR spectroscopy. Ab initio crystal structure determination was carried out using X-ray powder diffraction techniques. The compound crystallizes in monoclinic lattice with unit cell parameters: a = 15.193(1) Aa, b = 12.005(1) Aa, c = 10.842(1) Aa, β = 109.15(1) , V = 1868.11 Aa{sup 3}, Z = 4, SG = Cc. The type of carbohydrazide coordination was additionally confirmed by {sup 15}N MAS CP NMR and IR spectroscopy. In the complex ion [UO{sub 2}((N{sub 2}H{sub 3}){sub 2}CO){sub 3}]{sup 2+} three carbohydrazide ligands coordinate to UO{sub 2}{sup 2+} through oxygen and nitrogen forming three five-membered chelate rings. The carbohydrazide rings are tuned to the equatorial plane of complex. The crystal structure consists of zig-zag chains of [UO{sub 2}((N{sub 2}H{sub 3}){sub 2}CO){sub 3}]{sup 2+} cations stretched along c-axis. The cations in the chain are linked by the hydrogen bonds between the cations themselves. The anions are located in the pores between chains and participate in hydrogen bonding between adjacent chains and additionally link the chain sections. The length of the chain section is 5.768 Aa and the angle between sections is 140 . The substance [UO{sub 2}((N{sub 2}H{sub 3}){sub 2}CO){sub 3}](NO{sub 3}){sub 2} is thermally stable up to 215 C and then decomposes with an explosion.

  7. 3d-4f exchange interactions in R sub 2 Ni sub 17. [Dy sub 2 Ni sub 17; Ho sub 2 Ni sub 17; Er sub 2 Ni sub 17

    Energy Technology Data Exchange (ETDEWEB)

    Marquina, C.; Kayzel, F.E.; Ahn, T.H.; Radwanski, R.J.; Franse, J.J.M. (Van der Waals-Zeeman Lab., Univ. van Amsterdam (Netherlands))

    1992-02-01

    Magnetization isotherms at 4.2 K in fields up to 38 T have been measured on free powder samples R{sub 2}Ni{sub 17} (R=Dy, Ho and Er). From the transition-field values the intersublattice molecular-field coefficient n{sub RT} and molecular field acting on the R moment have been derived. (orig.).

  8. Structural and transport effects of doping perfluorosulfonic acid polymers with the heteropoly acids, H<sub>3sub>PW>12sub>O>40sub> or H<sub>4sub>SiW>12sub>O>40sub>

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Fanqin; Aieta, Niccolo V.; Dec, Steven F.; Horan, James L.; Williamson, Don; Frey, Matthew H.; Pham, Phat; Turner, John A.; Yandrasits, Michael A.; Hamrock, Steven J.; Herring, Andrew M.

    2007-12-01

    A perfluorosulfonic acid (PFSA) polymer with pendant side chain –O(CF<sub>2sub>)>4sub>SO>3sub>H was doped with the heteropoly acids (HPAs), H<sub>3sub>PW>12sub>O>40sub> and H<sub>4sub>SiW>12sub>O>40sub>. Infrared spectroscopy revealed a strong interaction between the HPA and the PFSA ionomer. Modes associated with the peripheral bonds of the HPA were shifted to lower wave numbers when doped into PFSA membranes. Small-angle X-ray scattering (SAXS) measurements showed the presence of large crystallites of HPA in the membrane with d spacings of ca. 10 Å, close to the lattice spacing observed in bulk HPA crystals. Under wet conditions the HPA was more dispersed and constrained the size of the sulfonic acid clusters to 20 Å at a 5 wt% HPA doping level, the same as in the vacuum treated ionomer samples. Under conditions of minimum hydration the HPA decreased the Ea for the self-diffusion of water from 27 to 15 kJ mol-1. The reverse trend was seen under 100% RH conditions. Proton conductivity measurements showed improved proton conductivity of the HPA doped PFSAs at a constant dew point of 80 °C for all temperatures up to 120 °C and at all relative hummidities up to 80%. The activation energy for proton conduction generally was lower than for the undoped materials at RH ≤80%. Significantly the Ea was 1/2 that of the undoped material at RHs of 40 and 60%. A practical proton conductivity of 113 mS cm-1 was observed at 100 °C and 80% RH.

  9. Synthesis of g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    He, Peizhi; Song, Limin [College of Environment and Chemical Engineering and State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Zhang, Shujuan, E-mail: songlmnk@sohu.com [College of Science, Tianjin University of Science and Technology (co-first institution), Tianjin 300457 (China); Wu, Xiaoqing [Institute of Composite Materials and Ministry of Education Key Laboratory of Advanced Textile Composite Materials, Tianjin Polytechnic University, Tianjin 300387 (China); Wei, Qingwu [College of Environment and Chemical Engineering and State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China)

    2014-03-01

    Graphical abstract: g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst with visible-light response was prepared by a facile coprecipitation method. The results show that g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} possesses a much higher activity for the decomposition of RhB than that of the pure Ag{sub 3}PO{sub 4} particles. The most mechanism is that g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst can efficiently separate the photogenerated electron–hole pairs, enhancing the photocatalytic activity of g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} composites. - Highlights: • g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction showed much higher activity than that of Ag{sub 3}PO{sub 4}. • The high activity could be attributed to g-C{sub 3}N{sub 4} for modifying Ag{sub 3}PO{sub 4}. • More ·OH radicals may be significant reason to improve Ag{sub 3}PO{sub 4} activity. - Abstract: g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst with visible-light response was prepared by a facile coprecipitation method. The photocatalysts were characterized by X-ray powder diffraction, transmission electron microscopy, UV–vis absorption spectroscopy and Fourier transform infrared spectroscopy. The photocatalytic activities of the obtained samples were tested by using Rhodamine B (RhB) as the degradation target under visible light irradiation. g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} decomposed RhB more effectively than the pure Ag{sub 3}PO{sub 4} particles did, and 2 wt.% g-C{sub 3}N{sub 4} had the highest activity. Furthermore, 2 wt.% g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} degraded high-concentration RhB more potently than unmodified Ag{sub 3}PO{sub 4} did, probably because g-C{sub 3}N{sub 4}/Ag{sub 3}PO{sub 4} heterojunction photocatalyst enhanced the photocatalytic activity by efficiently separating the photogenerated electron–hole pairs.

  10. Structures and phases transition in hexylenediammonium pentachlorobismuthate (III) [NH{sub 3}(CH{sub 2}){sub 6}NH{sub 3}]BiCl{sub 5} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Ouasri, A., E-mail: aouasri@yahoo.fr [Equipe de Physico-Chimie des Matériaux Inorganiques, Université Ibn Tofail, Faculté des Sciences, B. P. 133, Kenitra 14000 (Morocco); Département de Physique-Chimie, Centre Régional des Métiers de l' Education, et de la Formation, Souissi Rabat (Morocco); Jeghnou, H.; Rhandour, A. [Equipe de Physico-Chimie des Matériaux Inorganiques, Université Ibn Tofail, Faculté des Sciences, B. P. 133, Kenitra 14000 (Morocco); Roussel, P. [Unité de Catalyse et de Chimie du Solide, CNRS UMR 8181 (Equipe de Chimie du Solide), ENSCL, USTL, VILLENEUVE D' ASCQ Cedex 59655 (France)

    2013-04-15

    The crystal structure of [NH{sub 3}(CH{sub 2}){sub 6}NH{sub 3}]BiCl{sub 5} was determined at: 223 K [P2{sub 1}2{sub 1}2{sub 1} (Z=4), a=7.788(1), b=13.886(2), c=13.972(2) Å], 308 K [P2{sub 1}/n (Z=8), a=19.972(3), b=7.772(2), c=20.166(3) Å, β=92.32(1)°] and 378 K [Pnma (Z=4), a=13911(2), b=7.834(7), c=14.457(2) Å]. It was consisted of isolated (BiCl{sub 5}{sup 2−}){sub n} anionic chains composed by distorted octahedra BiCl{sub 6}{sup 3−} sharing two corners and {sup +}NH{sub 3}(CH{sub 2}){sub 6}NH{sub 3}{sup +} cations placed in the free cavities between anionic chains. In the β phase, there are two crystallographically inequivalent cations and two one-dimensional anionic chains (BiCl{sub 5}{sup 2−}){sub n} in which BiCl{sub 6}{sup 3−} octahedra was doubly tilted and simply tilted. Two structural phase transitions at low and high temperatures α (P2{sub 1}2{sub 1}2{sub 1}, 223 K)↔β (P2{sub 1}/n, 308 K)↔γ (Pnma, 373 K) are observed and discussed. It was crystallographically showed that both anionic and cationic entities contribute to phase transitions mechanisms. The BiCl{sub 6}{sup 3−} octahedra were found to posses significant distortions on decreasing temperature and became more distorted in α (223 K) phase. It is argued that these deformations are caused by weak to moderate N--H···Cl hydrogen bonding. - Graphical abstract: Projection of the crystal structure of [NH{sub 3}(CH{sub 2}){sub 6}NH{sub 3}]BiCl{sub 5} down the a axis at 208 K. Highlights: ► The crystal shows two phase transitions: α(223 K)↔β(308 K)↔γ(373 K). ► A discontinuous transition may be occurred between α and β phases. ► The α↔β and β↔γ phase transitions are of first order. ► Both anionic and cationic motions contribute to phase transition mechanisms. ► The BiCl{sub 6}{sup 3−} octahedra showed significant distortions on decreasing temperature.

  11. Structure and thermodynamic stability of UTa <sub>3sub> O <sub>10sub> , a U( v )-bearing compound

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaofeng; Lipp, Christian; Tiferet, Eitan; Lanzirotti, Antonio; Newville, Matthew; Engelhard, Mark H.; Wu, Di; Ilton, Eugene S.; Sutton, Stephen R.; Xu, Hongwu; Burns, Peter C.; Navrotsky, Alexandra

    2016-09-09

    Heating a mixture of uranyl(VI) nitrate and tantalum(V) oxide in the molar ratio of 2 : 3 to 1400 °C resulted in the formation of a new compound, UTa<sub>3sub>O>10sub>. The honey colored to yellow brown crystals of UTa<sub>3sub>O>10sub> crystallize in an orthorhombic structure with the space group Fddd (no. 70), lattice parameters a = 7.3947(1), b = 12.7599(2), c = 15.8156(2) Å, and Z = 8. Vertex sharing [TaO<sub>6sub>]7- octahedra of two crystallographically distinct Ta cations form a three dimensional tantalate framework. Within this framework, six membered rings of [TaO<sub>6sub>]7- octahedra are formed within the (001) plane. The center of these rings is occupied by the uranyl cations [UO<sub>2sub>]+, with an oxidation state of +5 for uranium. The pentavalence of U and Ta was confirmed by X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy. The enthalpy of formation of UTa<sub>3sub>O>10sub> from Ta<sub>2sub>O>5sub>, β-U<sub>3sub>O>7sub>, and U<sub>3sub>O>8sub> has been determined to be 13.1 ± 18.1 kJ mol-1 using high temperature oxide melt solution calorimetry with sodium molybdate as the solvent at 700 °C. The close to zero enthalpy of formation of UTa<sub>3sub>O>10sub> can be explained by closely balanced structural stabilizing and destabilizing factors, which may also apply to other UM<sub>3sub>O>10sub> compounds.

  12. Synthesis and characterization of highly efficient and stable Pr{sub 6}O{sub 11}/Ag{sub 3}PO{sub 4}/Pt ternary hybrid structure

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Jiatao; Liu, Lin; Niu, Tongjun; Sun, Xiaosong, E-mail: sunxs@scu.edu.cn

    2017-05-01

    Highlights: • Visible-light-driven Pr{sub 6}O{sub 11}/Ag{sub 3}PO{sub 4}/Pt photocatalysts were prepared. • Pr{sub 6}O{sub 11}/Ag{sub 3}PO{sub 4}/Pt showed highly efficient and stable photocatalystic activity. • The photocatalytic mechanism of Pr{sub 6}O{sub 11}/Ag{sub 3}PO{sub 4}/Pt composite was given. - Abstract: Ag{sub 3}PO{sub 4} is an excellent photocatalyst with high efficiency and quantum yield, but suffers from the fast recombination of photogenerated electron-hole pairs and photo-corrosion. Hereby, the highly efficient and stable visible-light-driven Pr{sub 6}O{sub 11}/Ag{sub 3}PO{sub 4}/Pt photocatalyst were prepared via a three-step wet chemical approach. The as-prepared Pr{sub 6}O{sub 11}/Ag{sub 3}PO{sub 4}/Pt composite was characterized by X-ray diffraction, US-vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectra and transient photocurrent as well. Comparing with single Pr{sub 6}O{sub 11} or Ag{sub 3}PO{sub 4}, the prepared Pr{sub 6}O{sub 11}/Ag{sub 3}PO{sub 4}/Pt composite exhibited much higher photocatalytic activity and stability for the degradation of Rhodamine B under visible light irradiation (>420 nm). The enhanced photocatalytic performance of Pr{sub 6}O{sub 11}/Ag{sub 3}PO{sub 4}/Pt composite has been attributed to the efficient separation of photo-generated electron-hole pairs through a scheme system composed of Pr{sub 6}O{sub 11,} Ag{sub 3}PO{sub 4} and Pt.

  13. AOI [3] High-Temperature Nano-Derived Micro-H<sub>2sub> and - H<sub>2sub>S Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Sabolsky, Edward M. [West Virginia Univ., Morgantown, WV (United States)

    2014-08-01

    The emissions from coal-fired power plants remain a significant concern for air quality. This environmental challenge must be overcome by controlling the emission of sulfur dioxide (SO<sub>2sub>) and hydrogen sulfide (H<sub>2sub>S) throughout the entire coal combustion process. One of the processes which could specifically benefit from robust, low cost, and high temperature compatible gas sensors is the coal gasification process which converts coal and/or biomass into syngas. Hydrogen (H<sub>2sub>), carbon monoxide (CO) and sulfur compounds make up 33%, 43% and 2% of syngas, respectively. Therefore, development of a high temperature (>500°C) chemical sensor for in-situ monitoring of H<sub>2sub>, H<sub>2sub>S and SO2<sub>2sub> levels during coal gasification is strongly desired. The selective detection of SO<sub>2sub>/H>2sub>S in the presence of H<sub>2sub>, is a formidable task for a sensor designer. In order to ensure effective operation of these chemical sensors, the sensor system must inexpensively function within harsh temperature and chemical environment. Currently available sensing approaches, which are based on gas chromatography, electrochemistry, and IR-spectroscopy, do not satisfy the required cost and performance targets. This work focused on the development microsensors that can be applied to this application. In order to develop the high- temperature compatible microsensor, this work addressed various issues related to sensor stability, selectivity, and miniaturization. In the research project entitled “High-Temperature Nano-Derived Micro-H<sub>2sub> and -H<sub>2sub>S Sensors”, the team worked to develop micro-scale, chemical sensors and sensor arrays composed of nano-derived, metal-oxide composite materials to detect gases like H<sub>2sub>, SO<sub>2sub>, and H<sub>2sub>S within high-temperature environments (>500°C). The research was completed in collaboration with NexTech Materials, Ltd. (Lewis Center, Ohio). Nex

  14. Comparing the dynamic and thermodynamic behaviors of Al{sub 86}Ni{sub 9}-La{sub 5}/(La{sub 0.5}Ce{sub 0.5}){sub 5} amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li, G.H. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Wang, W.M. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: weiminw@sdu.edu.cn; Bian, X.F.; Zhang, J.T.; Li, R.; Wang, L. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

    2009-06-10

    The dynamic viscosities and thermodynamic dilatometric behaviors of Al{sub 86}Ni{sub 9}La{sub 5} and Al{sub 86}Ni{sub 9}(La{sub 0.5}Ce{sub 0.5}){sub 5} amorphous alloys were investigated using viscometer, differential scanning calorimetry (DSC) and conventional dilatometer. Comparing with Al{sub 86}Ni{sub 9}La{sub 5} alloy, Al{sub 86}Ni{sub 9}(La{sub 0.5}Ce{sub 0.5}){sub 5} alloy exhibits a larger viscosity and a larger average thermal expansion coefficient in the linear expansion zone ({alpha}{sub exp}). The viscosity and thermal expansion data suggest that the partial substitution La by Ce decreases the quantity of free volume in Al-Ni-La system by improving the continuous degree of atomic size, which leads to the improvement of glass forming ability.

  15. Formation, stability and structural characterization of ternary MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) complexes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun-Yeop; Yun, Jong-Il [KAIST, Daejeon (Korea, Republic of). Dept. of Nuclear and Quantum Engineering; Vespa, Marika; Gaona, Xavier; Dardenne, Kathy; Rothe, Joerg; Rabung, Thomas; Altmaier, Marcus [Karlsruhe Institute of Technology, Karlsruhe (Germany). Inst. for Nuclear Waste Disposal

    2017-06-01

    The formation of ternary Mg-UO{sub 2}-CO{sub 3} complexes under weakly alkaline pH conditions was investigated by time-resolved laser fluorescence spectroscopy (TRLFS) and extended X-ray absorption fine structure (EXAFS) and compared to Ca-UO{sub 2}-CO{sub 3} complexes. The presence of two different Mg-UO{sub 2}-C{sub 3} complexes was identified by means of two distinct fluorescence lifetimes of 17±2 ns and 51±2 ns derived from the multi-exponential decay of the fluorescence signal. Slope analysis in terms of fluorescence intensity coupled with fluorescence intensity factor as a function of log [Mg(II)] was conducted for the identification of the Mg-UO{sub 2}-CO{sub 3} complexes forming. For the first time, the formation of both MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) species was confirmed and the corresponding equilibrium constants were determined as log β {sub 113}=25.8±0.3 and β {sub 213}=27.1±0.6, respectively. Complementarily, fundamental structural information for both Ca-UO{sub 2}-CO{sub 3} and Mg-UO{sub 2}-CO{sub 3} complexes was gained by extended EXAFS revealing very similar structures between these two species, except for the clearly shorter U-Mg distance (3.83 Aa) compared with U-Ca distance (4.15 Aa). These results confirmed the inner-sphere character of the Ca/Mg-UO{sub 2}-CO{sub 3} complexes. The formation constants determined for MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) species indicate that ternary Mg-UO{sub 2}-CO{sub 3} complexes contribute to the relevant uranium species in carbonate saturated solutions under neutral to weakly alkaline pH conditions in the presence of Mg(II) ions, which will induce notable influences on the U(VI) chemical species under seawater conditions.

  16. Structure and physical properties of Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Fang; Forbes, Scott [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada); Ramachandran, Krishna Kumar [Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada); Mozharivskyj, Yurij, E-mail: mozhar@mcmaster.ca [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada)

    2015-11-25

    The Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} phase was prepared by arc-melting, while the Cr{sub 5}B{sub 3}-type Ta{sub 5}Ge{sub 3} one was synthesized through sintering at 1000 °C. X-ray single crystal diffraction was employed to elucidate their structure. According to the magnetization measurements, both Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} are Pauli paramagnets, with Ta{sub 5}Ge{sub 3} showing a Curie-Weiss-like paramagnetic behavior at low temperatures likely due to presence of paramagnetic impurity. Both Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} display a very low electrical resistivity from 2 to 300 K. The resistivity is constant below 20 K, but displays a positive temperature coefficient above 20 K. Electronic structure calculations with the TB-LMTO-ASA method support the metallic character of the two phases and suggest that the bonding is optimized in both phases. - Highlights: • Synthesis of Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phases with high purity by arc-melting and sintering, respectively. • Magnetization data and electrical resistivity of the Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phases. • Crystal and electronic structure analysis for Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phase by X-ray diffraction and TB-LMTO-ASA calculations.

  17. On ternary intermetallic aurides. CaAu{sub 2}Al{sub 2}, SrAu{sub 2-x}Al{sub 2+x} and Ba{sub 3}Au{sub 5+x}Al{sub 6-x}

    Energy Technology Data Exchange (ETDEWEB)

    Stegemann, Frank [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Benndorf, Christopher [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Institut fuer Physikalische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Institut fuer Mineralogie, Kristallographie und Materialwissenschaften, Universitaet Leipzig (Germany); Zhang, Yuemei; Fokwa, Boniface P.T. [Department of Chemistry, University of California, Riverside, CA (United States); Bartsch, Manfred; Zacharias, Helmut [Physikalisches Institut, Westfaelische Wilhelms-Universitaet Muenster (Germany); Eckert, Hellmut [Institut fuer Physikalische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos, SP (Brazil); Janka, Oliver [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Institut fuer Chemie, Carl von Ossietzky Universitaet Oldenburg (Germany)

    2017-11-17

    The intermetallic compound CaAu{sub 2}Al{sub 2}, and the members of the solid solutions SrAu{sub 2-x}Al{sub 2+x} (0 ≤ x ≤ 0.33) and Ba{sub 3}Au{sub 5+x}Al{sub 6-x} (x = 0, 0.14, 0.49) were synthesized from the elements in sealed tantalum ampoules. The Ca compound crystallizes with the orthorhombic ThRu{sub 2}P{sub 2} type structure, whereas the targeted SrAu{sub 2}Al{sub 2} was found to form a solid solution according to SrAu{sub 2-x}Al{sub 2+x}. For the Ba system no ''BaAu{sub 2}Al{sub 2}'' was found, however, Ba{sub 3}Au{sub 5+x}Al{sub 6-x} was discovered to crystallize in the monoclinic space group C2/c with its own structure type. The samples were investigated by powder X-ray diffraction and their crystal structures were refined on the basis of single-crystal X-ray diffraction data. All compounds were characterized furthermore by susceptibility measurements. The crystallographic aluminum sites of CaAu{sub 2}Al{sub 2} and Ba{sub 3}Au{sub 5}Al{sub 6} can be differentiated by {sup 27}Al solid state NMR spectra on the basis of their different electric field gradients, in agreement with theoretical calculations. The electron transfer from the alkaline earth metals and the aluminum atoms onto the gold atoms was investigated by X-ray photoelectron spectroscopy (XPS) classifying these intermetallics as aurides, in full agreement with the calculated Bader charges. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Mechanisms of Re/sub 2/(CO)/sub 10/ substitution reactions: crossover experiments with /sup 185/Re/sub 2/(CO)/sub 10/ and /sup 187/Re/sub 2/(CO)/sub 10/

    Energy Technology Data Exchange (ETDEWEB)

    Stolzenberg, A.M.; Muetterties, E.L.

    1983-02-23

    /sup 185/Re/sub 2/(CO)/sub 10/ and /sup 187/Re/sub 2/(CO)/sub 10/ were prepared separately and then utilized in combination in crossover experiments to probe for fragmentation to mononuclear rhenium species in thermal and photochemically initiated substitution reactions. For the CO-Re/sub 2/(CO)/sub 10/ exchange reaction, a reaction separately analyzed for /sup 13/CO-/sup 12/CO interchange, no crossover was observed at 150/sup 0/C after 14 half-lives of reaction (14 h). Similarly, the thermal reaction sequences of Re/sub 2/(CO)/sub 10/ + P(C/sub 6/H/sub 5/)/sub 3/ reversible Re/sub 2/(CO)/sub 9/P(C/sub 6/H/sub 5/)/sub 3/ + CO and Re/sub 2/(CO)/sub 9/P(C/sub 6/H/sub 5/)/sub 3/ + P(C/sub 6/H/sub 5/)/sub 3/ reversible Re/sub 2/(CO)/sub 8/(P(C/sub 6/H/sub 5/)/sub 3/)/sub 2/ + CO were examined at 150/sup 0/C (maintaining a CO pressure of approx. 560 to 640 mm). No crossover was detectable in either Re/sub 2/(CO)/sub 10/ or Re/sub 2/(CO)/sub 9/P(C/sub 6/H/sub 5/)/sub 3/ (relative to blank experiments). Hence, phosphine substitution reactions proceed without a detectable formation of mononuclear rhenium species. These observations support a CO dissociative mechanism. A model based upon this mechanism can accurately reproduce the mass spectra observed during /sup 13/CO-/sup 12/CO interchange. In the absence of a CO atmosphere, /sup 185/Re/sub 2/(CO)/sub 10/ and /sup 187/Re/sub 2/(CO)/sub 10/ formed /sup 185/Re/sup 187/Re(CO)/sub 10/, and this interchange was nearly complete at 150/sup 0/C within 14 to 16 half-lives. All photochemically initiated reactions with the two labeled decacarbonyls led to complete crossover within short reaction times. It appears then that the primary mode of reaction for Re/sub 2/(CO)/sub 10/ under photolysis conditions involves Re-Re bond scission as an early elementary step. Also, the reversible steps leading to the precursor(s) to Re/sub 2/(CO)/sub 10/ decomposition include scission of the rhenium-rhenium bond.

  19. Dielectric and ferroelectric characteristics of Ba{sub 4}Pr{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30} tungsten bronze ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ting Ting; Chen, Wang; Zhu, Xiao Na; Zhu, Xiao Li; Chen, Xiang Ming, E-mail: xmchen59@zju.edu.cn

    2016-09-15

    Ba{sub 4}Pr{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30} tungsten bronze ceramics have been prepared by a standard solid-state sintering method, and the electrical, dielectric and ferroelectric properties have been determined together with the structure. The structure dependence of ferroelectricity has been investigated by comparing the as-sintered, N{sub 2}-annealed and O{sub 2}-annealed samples. The typical relaxor ferroelectric nature is generally indicated in the present ceramics, where the broaden dielectric constant and dielectric loss peaks with strong frequency dispersion feature are observed. The peak temperatures for both dielectric constant and dielectric loss are significantly increased together with the much stronger frequency dispersion by N{sub 2}-annealing, while the O{sub 2}-annealing results in the decreased peak temperatures and the suppressed frequency dispersion. These phenomena are closely related to the valences of Fe and Pr ions. The hopping between Fe{sup 2+} and Fe{sup 3+} inside the grains causes the dielectric relaxation in as-sintered and N{sub 2}-annealed samples. The enhanced ferroelectricity near room temperature is attributed to the increased ion radius difference between A1 and A2 ions because of the “substitution” Pr{sup 4+} for Pr{sup 3+} after N{sub 2}-annealing. - Highlights: • Dielectric and ferroelectric properties of Ba{sub 4}Pr{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30} are investigated. • Ferroelectric hysteresis loop is observed in Ba{sub 4}Pr{sub 2}Fe{sub 2}Nb{sub 8}O{sub 30} ceramics. • The ferroelectric properties are closely related to the valences of Pr ions. • The ferroelectric transition temperature is dominated by the radius difference between A1-and A2-site.

  20. Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16}, the new tellurite halides of the tetragonal Rb{sub 6}LiNd{sub 11}[SeO{sub 3}]{sub 12}Cl{sub 16} structure type

    Energy Technology Data Exchange (ETDEWEB)

    Charkin, Dmitri O. [Department of Chemistry, Moscow State University, GSP-1, 119991 Moscow (Russian Federation); Black, Cameron; Downie, Lewis J. [EaStCHEM and School of Chemistry, University of St Andrews, Purdie Building, St. Andrews, Fife KY169ST (United Kingdom); Sklovsky, Dmitry E. [Department of Chemistry, Moscow State University, GSP-1, 119991 Moscow (Russian Federation); SineTheta LTD, Moscow 119991 (Russian Federation); Berdonosov, Peter S., E-mail: berdonosov@inorg.chem.msu.ru [Department of Chemistry, Moscow State University, GSP-1, 119991 Moscow (Russian Federation); Olenev, Andrei V. [Department of Chemistry, Moscow State University, GSP-1, 119991 Moscow (Russian Federation); SineTheta LTD, Moscow 119991 (Russian Federation); Zhou, Wuzong; Lightfoot, Philip [EaStCHEM and School of Chemistry, University of St Andrews, Purdie Building, St. Andrews, Fife KY169ST (United Kingdom); Dolgikh, Valery A. [Department of Chemistry, Moscow State University, GSP-1, 119991 Moscow (Russian Federation)

    2015-12-15

    Two new rare-earth – alkali – tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} (I) and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16} (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn{sub 11}(TeO{sub 3}){sub 12}] and [M{sub 6}X{sub 16}] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted. - Graphical abstract: Two new rare-earth – alkali – tellurium oxide halides were predicted and synthesized. - Highlights: • Two new rare-earth – alkali – tellurium oxide halides were synthesized. • They adopt slab structure of rare earth-tellurium-oxygen and CsCl-like slabs. • The Br-based CsCl-like slabs have been observed first in this layered family.

  1. Nido-Carborane building-block reagents. 2. Bulky-substituent (alkyl)/sub 2/C/sub 2/B/sub 4/H/sub 6/ derivatives and (C/sub 6/H/sub 5/)/sub 2/C/sub 2/B/sub 4/H/sub 6/: synthesis and properties

    Energy Technology Data Exchange (ETDEWEB)

    Boyter, H.A. Jr.; Grimes, R.N.

    1988-09-07

    The preparation and chemistry of nido-2,3-R/sub 2/C/sub 2/C/sub 2/B/sub 4/H/sub 6/ carboranes in which R is n-butyl, isopentyl, n-hexyl, and phenyl was investigated in order to further assess the steric and electronic influence of the R groups on the properties of the nido-C/sub 2/B/sub 4/ cage, especially with respect to metal complexation at the C/sub 2/B/sub 3/ face and metal-promoted oxidative fusion. The three dialkyl derivatives were prepared from the corresponding dialkylacetylenes via reaction with B/sub 5/H/sub 9/ and triethylamine, but the diphenyl compound could not be prepared in this manner and was obtained instead in a thermal reaction of B/sub 5/H/sub 9/ with diphenylacetylene in the absence of amine. All four carboranes are readily bridge-deprotonated by NaH in THF, and the anions of the dialkyl species, on treatment with FeCl/sub 2/ and air oxidation, generate the respective R/sub 4/C/sub 4/B/sub 8/H/sub 8/ carborane fusion products were R = n-C/sub 4/H/sub 9/, i-C/sub 5/H/sub 11/ or n-C/sub 6/H/sub 13/. The diphenylcarborane anion Ph/sub 2/C/sub 2/B/sub 4/H/sub 5//sup /minus// did not form detectable metal complexes with Fe/sup 2+/, Co/sup 2+/, or Ni/sup 2+/, and no evidence of a Ph/sub 4/C/sub 4/B/sub 8/H/sub 8/ fusion product has been found. Treatment of Ph/sub 2/C/sub 2/B/sub 4/H/sub 6/ with Cr(CO)/sub 6/ did not lead to metal coordination of the phenyl rings, unlike (PhCH/sub 2/)/sub 2/C/sub 2/B/sub 4/H/sub 6/, which had previously been shown to form mono- and bis(tricarbonylchromium) complexes. However, the reaction of Ph/sub 2/C/sub 2/B/sub 4/H/sub 5//sup /minus//, CoCl/sub 2/, and (PhPCH/sub 2/)/sub 2/ did give 1,1-(Ph/sub 2/PCH/sub 2/)/sub 2/-1-Cl-1,2,3-Co(Ph/sub 2/C/sub 2/B/sub 4/H/sub 4/), the only case in which metal complexation of the diphenylcarborane was observed. 14 references, 3 figures, 3 tables.

  2. Atomic pair distribution function at the Brazilian Synchrotron Light Laboratory: application to the Pb<sub>1–xsub> La<sub>x>Zr <sub>0.40sub>Ti>0.60sub>O>3sub> ferroelectric system

    Energy Technology Data Exchange (ETDEWEB)

    Saleta, M. E.; Eleotério, M.; Mesquita, A.; Mastelaro, V. R.; Granado, E.

    2017-07-29

    This work reports the setting up of the X-ray diffraction and spectroscopy beamline at the Brazilian Synchrotron Light Laboratory for performing total scattering experiments to be analyzed by atomic pair distribution function (PDF) studies. The results of a PDF refinement for Al<sub>2sub>O>3sub> standard are presented and compared with data acquired at a beamline of the Advanced Photon Source, where it is common to perform this type of experiment. A preliminary characterization of the Pb<sub>1–xsub>LaxZr>0.40sub>Ti>0.60sub>O>3sub> ferroelectric system, withx= 0.11, 0.12 and 0.15, is also shown.

  3. Phase relations of Li{sub 2}O–MnO–P{sub 2}O{sub 5} system and the electrochemical properties of Li{sub 1+x}Mn{sub 1−x}PO{sub 4} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Danlin [School of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Zhao, Yanming, E-mail: zhaoym@scut.edu.cn [School of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China); School of Physics, South China University of Technology Guangzhou, 510640 (China); Dong, Youzhong; Liang, Zhiyong; Lin, Xinghao [School of Material Science and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2015-07-05

    Graphical abstract: Subsolidus phase relations of the LiO{sub 2}–MnO–P{sub 2}O{sub 5} system: (A) Li{sub 1+x}Mn{sub 1−x}PO{sub 4} (−0.05 ⩽ x ⩽ 0.03); (B) Li{sub 2}MnP{sub 2}O{sub 7}; (C) Li{sub 2}Mn(PO{sub 3}){sub 4}; and (D) LiMn(PO{sub 3}){sub 3}; dots: single phase; square: two phases; triangle: three phases. The phase relations of Li{sub 2}O–MnO–P{sub 2}O{sub 5} ternary system under reducing atmosphere have been systematically investigated by means of X-ray diffraction for the first time. A high-pressure phase Mn{sub 3}(PO{sub 4}){sub 2} can be easily obtained in the MnO–P{sub 2}O{sub 5} system and its detail structure is presented. In addition, the solid solubility of Li{sub 1+x}Mn{sub 1−x}PO{sub 4} is determined as −0.05 ⩽ x ⩽ 0.03, and electrochemical properties of Li{sub 1+x}Mn{sub 1−x}PO{sub 4} are investigated. - Highlights: • The phase relations of Li{sub 2}O–MnO–P{sub 2}O{sub 5} ternary system were reported for the first time. • A high-pressure Mn{sub 3}(PO{sub 4}){sub 2} was prepared under normal the solid-state reaction. • The detail structure for high-pressure Mn{sub 3}(PO{sub 4}){sub 2} was presented for the first time. • The solid solubility of Li{sub 1+x}Mn{sub 1−x}PO{sub 4} (−0.05 ⩽ x ⩽ 0.03) were reported for the first time. • The electrochemical properties of Li{sub 1+x}Mn{sub 1−x}PO{sub 4} were studied. - Abstract: The phase relations of Li{sub 2}O–MnO–P{sub 2}O{sub 5} ternary system under reducing atmosphere have been systematically investigated by means of X-ray diffraction. Inferior to what we expected, no other new lithium manganese phosphates exist within the Li{sub 2}O–MnO–P{sub 2}O{sub 5} ternary system under the reducing atmosphere. A high-pressure phase Mn{sub 3}(PO{sub 4}){sub 2} with graftonite Fe{sub 3}(PO{sub 4}){sub 2}-type structure can be easily obtained in the MnO–P{sub 2}O{sub 5} system under the ordinary solid-state reaction conditions in H{sub 2}/Ar atmosphere

  4. Ferroelectric TGS ((NH sub 2 CH sub 2 COOH) sub 3 centre dot H sub 2 SO sub 4) under high pressure

    CERN Document Server

    Kobayashi, Y; Furuta, H; Endo, S; Deguchi, K

    2002-01-01

    The ferroelectric transition temperature T sub c of (NH sub 2 CH sub 2 COOH) sub 3 centre dot H sub 2 SO sub 4 (TGS), which is a typical order-disorder-type ferroelectric, was determined by dielectric constant and Raman scattering measurements under high pressure. T sub c increased, passed through a maximum and then decreased slightly with increasing pressure, and then abruptly dropped at about 2.5 GPa, where a transition to a new high-pressure phase was confirmed to exist. A tentative p-T phase diagram was proposed for TGS.

  5. New phases in the ZrO{sub 2}-Bi{sub 2}O{sub 3} and HfO{sub 2}-Bi{sub 2}O{sub 3} systems

    Energy Technology Data Exchange (ETDEWEB)

    Sorokina, S.L.; Sleight, A.W. [Oregon State Univ., Corvallis, OR (United States)

    1998-07-01

    New phases of the type M{sub 1{minus}x}Bi{sub x}O{sub 2{minus}x/2} with a defect fluorite structure have been prepared where M is Zr or Hf. These apparently metastable phases were prepared by precipitation from solution followed by calcination at 600 C. For the Hf{sub 1{minus}x}Bi{sub x}O{sub 2{minus}x/2} system, x ranges from x = 0.40 to x = 0.75. For the Zr{sub 1{minus}x}Bi{sub x}O{sub 2{minus}x/2} system, x ranges from x = 0.50 to x = 0.75. Heating the defect fluorite Hf{sub 1{minus}x}Bi{sub x}O{sub 2-x/2} phases to temperatures of 700 to 950 C leads to the formation of Bi{sub 2}Hf{sub 2}O{sub 7} with the Bi{sub 2}Sn{sub 2}O{sub 7} structure. Thus, Bi{sub 2}Hf{sub 2}O{sub 7} is pseudocubic, but apparently face centered tetragonal with a = 21.66 {angstrom} and c = 21.84 {angstrom}. When Bi{sub 2}Hf{sub 2}O{sub 7} is heated to 1000 C, it decomposes into HfO{sub 2} and Bi{sub 1.94}Hf{sub 0.06}O{sub 3.03} with the {beta}-Bi{sub 2}O{sub 3} structure. Heating the defect fluorite Zr{sub 1{minus}x}Bi{sub x}O{sub 2{minus}x/2} phases to higher temperatures never produced a Bi{sub 2}Zr{sub 2}O{sub 7} phase with the Bi{sub 2}Sn{sub 2}O{sub 7} structure. Instead, the compositional range of the defect fluorite structure steadily decreases with increasing temperature, and this phase had completely decomposed at 750 C into ZrO{sub 2} and Bi{sub 1.84}Zr{sub 0.16}O{sub 3.08} with the {beta}-Bi{sub 2}O{sub 3} structure.

  6. Room-temperature structure of La sub 2 O sub 2 S sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Ostorero, J. (Centre National de la Recherche Scientifique, 92 - Meudon-Bellevue (France). Lab. de Magnetisme et d' Optique des Solides); Leblanc, M. (Le Mans Univ., 72 (France). Lab. des Fluorures)

    1990-08-15

    Lanthanum oxide sulfide La{sub 2}O{sub 2}S{sub 2}, M{sub r}=373.947, orthorhombic, Cmca, a=13.215 (2), b=5.943 (1), c=5.938 (1) A, V=466.3 (2) A{sup 3}, Z=4, D{sub x}=5.32 Mg m{sup -3}, Mo K{alpha}, {lambda}=0.71069 A, {mu}=18.87 mm{sup -1}, F(000)=648, R=0.017, 582 unique observed reflections, flux growth, data corrected for twinning of the crystal. The structure is built from infinitive layers of LaO{sub 4}S{sub 4} square antiprisms connected by edges; these layers share either oxygen or disulfide common planes. Short S-S distances (d=2.103 (2) A) correspond to S{sub 2}{sup 2-} entities. (orig.).

  7. Vortex melting line and dimensional crossover in Ba{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n}(O{sub 1-y},F{sub y}){sub 2} cuprate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Shivagan, D.D.; Shirage, P.M. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Crisan, A. [National Institute for Materials Physics, P.O. Box MG-7, 077125 Bucharest (Romania); Department of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT (United Kingdom); Tanaka, Y. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan)], E-mail: y.tanaka@aist.go.jp; Iyo, A.; Kodama, Y. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Tokiwa, K.; Watanabe, T. [Department of Applied Electronics, Tokyo University of Science, Noda, Chiba 278-8510 (Japan); Terada, N. [Department of Nano Structures and Advanced Materials, Kagoshima University, Kagoshima 890-0065 (Japan); Hamada, N. [Department of Physics, Tokyo University of Science, Noda, Chiba 278-8510 (Japan)

    2008-04-01

    Ba{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n}(O{sub 1-y},F{sub y}){sub 2}[F(2y)-02(n - 1)n], homologous series with F-substitution at apical oxygen site possess a thinner, 7.4 A, charge reservoir layer (CRL) and a strong interlayer vortex coupling was expected in these systems. We measured the vortex melting lines of high pressure synthesized Ba{sub 2}Ca{sub 3}Cu{sub 4}O{sub 8}(O{sub 1-y}F{sub y}){sub 2} (2y = 2.0) multilayered system with 2 inner planes (IP) of CuO{sub 2} layers and Ba{sub 2}Ca{sub 1}Cu{sub 2}O{sub 4}(O{sub 1-y}F{sub y}){sub 2} (2y 1.4, 1.6 and 2.0) bilayer system with no IP; using fundamental and third harmonic susceptibility response carried out onto preferentially oriented crystallites at very low ac field amplitude and applied dc fields up to 12 T. These experimental melting lines are described by the commonly accepted theory of two-fluid model. We observed 3D to 2D crossover in heavily underdoped F(2.0)-0212 sample, whereas such a vortex lattice crossover is not evident in F(2.0)-0234 sample; and explained on the basis of heavily underdoped and self doped states.

  8. Measurement of the B0<sub>s> lifetime using the semileptonic decay channel B0<sub>s> → D-<sub>s>μ+vX

    Energy Technology Data Exchange (ETDEWEB)

    Lizarraga, Marco Antonio Carrasco [National Polytechnic Inst. (IPN), Zacatenco (Mexico). Centre for Research and Advanced Studies (CINVESTAV)

    2009-11-01

    We report a measurement of the B0<sub>s> lifetime in the semileptonic decay channel BB0<sub>s> → D-<sub>s>μ+vX (and its charge conjugate), using approximately 0.4 fb-1 of data collected with the DØ detector during 2002–2004. Using 5176 reconstructed D-<sub>s> μ+ signal events, we have measured the B0<sub>s> lifetime to be τ (B0<sub>s>) = 1.398 ± 0.044 (stat)+0.028 <sub>-0.025sub> (syst) ps. This is the most precise measurement of the B0<sub>s> lifetime to date.

  9. Selective Detection of NO<sub>2sub> Using Cr-Doped CuO Nanorods

    Directory of Open Access Journals (Sweden)

    Kang-Min Kim

    2012-06-01

    Full Text Available CuO nanosheets, Cr-doped CuO nanosheets, and Cr-doped CuO nanorods were prepared by heating a slurry containing Cu-hydroxide/Cr-hydroxide. Their responses to 100 ppm NO<sub>2sub>, C<sub>2sub>H>5sub>OH, NH<sub>3sub>, trimethylamine, C<sub>3sub>H>8sub>, and CO were measured. For 2.2 at% Cr-doped CuO nanorods, the response (R<sub>a/Rg>, R<sub>a>: resistance in air, R<sub>g>: resistance in gas to 100 ppm NO<sub>2sub> was 134.2 at 250 °C, which was significantly higher than that of pure CuO nano-sheets (R<sub>a/Rg> = 7.5 and 0.76 at% Cr-doped CuO nanosheets (R<sub>a/Rg> = 19.9. In addition, the sensitivity for NO<sub>2sub> was also markedly enhanced by Cr doping. Highly sensitive and selective detection of NO<sub>2sub> in 2.2 at% Cr-doped CuO nanorods is explained in relation to Cr-doping induced changes in donor density, morphology, and catalytic effects.

  10. New vanadium tellurites: Syntheses, structures, optical properties of noncentrosymmetric VTeO{sub 4}(OH), centrosymmetric Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Ming-Li [College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Marsh, Matthew [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States); Shang, Xian-Xing [College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Mao, Jiang-Gao [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Albrecht-Schmitt, Thomas E. [Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States); Kong, Fang, E-mail: kongfang@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306 (United States)

    2017-05-15

    Two new vanadium tellurites, VTeO{sub 4}(OH) (1) and Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2), have been synthesized successfully with the use of hydrothermal reactions. The crystal structures of the two compounds were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the polar space group Pca2{sub 1} (No. 29) while compound 2 crystallizes in the centrosymmetric space group C2/c (No. 15). The topography of compound 1 reveals a two-dimensional, layered structure comprised of VO{sub 6} octahedral chains and TeO{sub 3}(OH) zig-zag chains. Compound 2, on the contrary, features a three-dimensional [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic framework with Ba{sup 2+} ions filled into the 10-member ring helical tunnels. The [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic network is the first 3D vanadium tellurite framework to be discovered in the alkaline-earth vanadium tellurite system. Powder second harmonic generation (SHG) measurements indicate that compound 1 shows a weak SHG response of about 0.3×KDP (KH{sub 2}PO{sub 4}) under 1064 nm laser radiation. Infrared spectroscopy, elemental analysis, thermal analysis, and dipole moment calculations have also been carried out. - Graphical abstract: VTeO{sub 4}(OH) (1) crystallizes in the noncentrosymmetric space group Pca2{sub 1} (No. 29) while Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) crystallizes in the centrosymmetric space group C2/c (No. 15). - Highlights: • VTeO{sub 4}(OH) (1) and Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) have been synthesized successfully with the use of hydrothermal reactions. • VTeO{sub 4}(OH) (1) crystallizes in the noncentrosymmetric space group Pca2{sub 1} and displays a weak SHG response. • VTeO{sub 4}(OH) (1) represents only the fourth SHG-active material found in vanadium tellurite systems. • Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) exhibits a novel three-dimensional [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10

  11. The Cu{sub 2}FeTi{sub 3}S{sub 8} and Cu{sub 2}FeZr{sub 3}S{sub 8} compounds: Crystal structure and electroanalytical application

    Energy Technology Data Exchange (ETDEWEB)

    Kormosh, Zh., E-mail: kormosh@univer.lutsk.ua [Department of Analytical Chemistry and Eco-technology, Volyn National University, 13 Voli Ave, 43025 Lutsk (Ukraine); Fedorchuk, A. [Department of Inorganic and Organic Chemistry, Lviv National University of Veterinary Medicine and Biotechnologies, 50 Pekarska St., 79010 Lviv (Ukraine); Wojciechowski, K. [Department of Inorganic Chemistry, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Tataryn, N. [Department of Analytical Chemistry and Eco-technology, Volyn National University, 13 Voli Ave, 43025 Lutsk (Ukraine); Parasyuk, O. [Department of Inorganic and Physical Chemistry, Volyn National University, 13 Voli Ave, 43025 Lutsk (Ukraine)

    2011-04-08

    The Cu{sub 2}FeTi{sub 3}S{sub 8} and Cu{sub 2}FeZr{sub 3}S{sub 8} compounds were produced by solid-state synthesis. The crystal structure of the quaternary phases was investigated by X-ray powder method. The compounds are described in the thiospinel structure (space group Fd3-bar m) with the unit cell parameters a = 1.00099(1) nm (Cu{sub 2}FeTi{sub 3}S{sub 8}) and a = 1.03837(2) nm (Cu{sub 2}FeZr{sub 3}S{sub 8}). The atomic parameters were calculated in the isotropic approximation (R{sub I} = 0.0496 and R{sub I} = 0.0422 for Cu{sub 2}FeTi{sub 3}S{sub 8} and Cu{sub 2}FeZr{sub 3}S{sub 8}, respectively). Iron(III)-selective electrodes were prepared using the chalcogenide compounds Cu{sub 2}FeTi{sub 3}S{sub 8} and Cu{sub 2}FeZr{sub 3}S{sub 8}. The electrode function slopes are 52.7 mV/pC for Cu{sub 2}FeTi{sub 3}S{sub 8} and 66.2 mV/pC for Cu{sub 2}FeZr{sub 3}S{sub 8}, the detection limits are 1 x 10{sup -5} M and 2 x 10{sup -5} M respectively. The prepared electrochemical sensors are not sensitive to Cd{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Co{sup 2+}, Mg{sup 2+}, Cr{sup 3+}, and Fe{sup 2+} ions, and were tested in the potentiometric titration of Fe(III) with EDTA solution.

  12. Structural features of layered iron pnictide oxides (Fe{sub 2}As{sub 2})(Sr{sub 4}M{sub 2}O{sub 6})

    Energy Technology Data Exchange (ETDEWEB)

    Ogino, H., E-mail: tuogino@mail.ecc.u-tokyo.ac.j [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); JST-TRIP, Sanban-cho, Chiyoda-ku, Tokyo 102-0075 (Japan); Sato, S.; Matsumura, Y.; Kawaguchi, N.; Ushiyama, K. [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); JST-TRIP, Sanban-cho, Chiyoda-ku, Tokyo 102-0075 (Japan); Katsura, Y. [Magnetic Materials Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Horii, S. [JST-TRIP, Sanban-cho, Chiyoda-ku, Tokyo 102-0075 (Japan); Kochi University of Technology, Kami, Kochi 782-8502 (Japan); Kishio, K.; Shimoyama, J. [Department of Applied Chemistry, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); JST-TRIP, Sanban-cho, Chiyoda-ku, Tokyo 102-0075 (Japan)

    2010-12-15

    Structural features of newly found perovskite-based iron pnictide oxide system have been studied. Compared to REFePnO system, perovskite-based system tend to have smaller Pn-Fe-Pn angle and higher pnictogen height owing to low electronegativity of alkaline earth metal and small repulsive force between pnictogen and oxigen atoms. As-Fe-As angles of (Fe{sub 2}As{sub 2})(Sr{sub 4}Cr{sub 2}O{sub 6}), (Fe{sub 2}As{sub 2})(Sr{sub 4}V{sub 2}O{sub 6}) and (Fe{sub 2}Pn{sub 2})(Sr{sub 4}MgTiO{sub 6}) are close to ideal tetrahedron and those pnictogen heights of about 1.40 A are close to NdFeAsO with optimized carrier concentration. These structural features of this system may lead to realization of high-T{sub c} superconductivity in this system.

  13. Evolution of the pi g sub 9 sub / sub 2 x nu h sub 1 sub 1 sub / sub 2 configuration in the neutron-rich sup 1 sup 1 sup 0 sup , sup 1 sup 1 sup 2 sub 4 sub 5 Rh and sup 1 sup 1 sup 4 sup , sup 1 sup 1 sup 6 sub 4 sub 7 Ag isotopes

    CERN Document Server

    Porquet, M G; Deloncle, I; Venkova, T; Astier, A; Buforn, N; Meyer, M; Prevost, A; Redon, N; Stezowski, O; Donadille, L; Dorvaux, O; Gall, B J P; Schulz, N; Lalkovski, S; Lucas, R; Minkova, A

    2003-01-01

    The sup 1 sup 1 sup 0 sup , sup 1 sup 1 sup 2 Rh and sup 1 sup 1 sup 4 sup , sup 1 sup 1 sup 6 Ag nuclei have been produced as fission fragments in the fusion reaction sup 1 sup 8 O+ sup 2 sup 0 sup 8 Pb at 85 MeV. Their level schemes have been built from gamma-rays detected using the Euroball IV array. High-spin states of these neutron-rich nuclei have been identified for the first time. The yrast structures consist of rotational bands in which the odd proton occupies the pi g sub 9 sub / sub 2 sub-shell and the odd neutron the nu h sub 1 sub 1 sub / sub 2 sub-shell. The evolution of the pi g sub 9 sub / sub 2 x nu h sub 1 sub 1 sub / sub 2 band structure is analyzed as a function of the neutron number.

  14. Enrichment of Sc{sub 2}O{sub 3} and TiO{sub 2} from bauxite ore residues

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Bona; Li, Guanghui, E-mail: liguangh@csu.edu.cn; Luo, Jun; Ye, Qing; Liu, Mingxia; Peng, Zhiwei; Jiang, Tao

    2017-06-05

    Highlights: • Sc{sub 2}O{sub 3} and TiO{sub 2} from bauxite ore residue were successfully enriched. • H{sub 3}PO{sub 4} and NaOH were efficient for enriching Sc{sub 2}O{sub 3} and TiO{sub 2} by removing SiO{sub 2}, Al{sub 2}O{sub 3}, and partial Fe{sub 2}O{sub 3} and CaO. • Enriching mechanism of Sc{sub 2}O{sub 3} and TiO{sub 2} was explicitly explained. - Abstract: As a major byproduct generated in the alumina industry, bauxite ore residue is an important reserve of scandium and titanium. In this study, the feasibility and mechanism of enriching Sc{sub 2}O{sub 3} and TiO{sub 2} from a non-magnetic material, which was obtained from carbothermal reductive roasting and magnetic separation of bauxite ore residue, were investigated based on a two-step (acidic and alkali) leaching process. It was revealed that approximately 78% SiO{sub 2} and 30–40% of CaO, FeO and Al{sub 2}O{sub 3} were removed from a non-magnetic material with 0.0134 wt.% Sc{sub 2}O{sub 3} and 7.64 wt.% TiO{sub 2} by phosphoric acidic leaching, while about 95% Al{sub 2}O{sub 3} and P{sub 2}O{sub 5} were further leached by subsequent sodium hydroxide leaching of the upper-stream leach residue. A Sc{sub 2}O{sub 3}-, TiO{sub 2}- rich material containing 0.044 wt.% Sc{sub 2}O{sub 3} and 25.5 wt.% TiO{sub 2} was obtained, the recovery and the enrichment factor of Sc{sub 2}O{sub 3} and TiO{sub 2} were about 85% and 5, respectively. The enrichment of Sc{sub 2}O{sub 3} was attributed to higher pH (>3.3) of phosphoric acid solution than its dissolution pH{sup 0}, and the enrichment of TiO{sub 2} was mainly associated with the insoluble perovskite (CaTiO{sub 3}) in the acidic solution at ambient temperature. As Sc{sub 2}O{sub 3} and TiO{sub 2} cannot be dissolved in the alkali solution, they were further enriched in the leach residue.

  15. Growth and structure of K{sub 2}Ni{sub x}Co{sub (1–x)}(SO{sub 4}){sub 2} · 6H{sub 2}O single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vasilyeva, N. A., E-mail: Natalie5590@mail.ru; Sorokina, N. I.; Antipin, A. M.; Verin, I. A.; Voloshin, A. E. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2016-01-15

    Single crystals of the K{sub 2}Ni{sub x}Co{sub (1–x)}(SO{sub 4}){sub 2} · 6H{sub 2}O composition are grown by spontaneous flux crystallization. More exact chemical formulas of the single crystals are determined based on the diffraction data as K{sub 2}Co(SO{sub 4}){sub 2} · 6H{sub 2}O (I), K{sub 2}(Co{sub 0.657}Ni{sub 0.343})(SO{sub 4}){sub 2} · 6H{sub 2}O (II), K{sub 2}(Co{sub 0.226}Ni{sub 0.774})(SO{sub 4}){sub 2} · 6H{sub 2}O (III), K{sub 2}(Co{sub 0.216}Ni{sub 0.784})(SO{sub 4}){sub 2} · 6H{sub 2}O (IV), and K{sub 2}Ni(SO{sub 4}){sub 2} · 6H{sub 2}O (V). The substitution of nickel atoms for cobalt atoms in structure I results in a shortening of all (Co,Ni)–O interatomic distances. With increasing Ni concentration, the (Co,Ni)–O2 distance shortens to a lesser degree than the (Co,Ni)–O1 and (Co,Ni)–O3 distances and, as a consequence, the distortion of (Co,Ni)O{sub 6} octahedra decreases. NiO{sub 6} polyhedra are less distorted than CoO{sub 6} octahedra. The analysis of difference syntheses of electron density shows that the number of uninterpretable peaks on the maps of mixed crystals II, III, and IV, as well as on the map of K{sub 2}Co(SO{sub 4}){sub 2} · 6H{sub 2}O, is larger with respect to those of structure K{sub 2}Ni(SO{sub 4}){sub 2} · 6H{sub 2}O.

  16. Photocatalytic activity of Bi{sub 2}WO{sub 6}/Bi{sub 2}S{sub 3} heterojunctions: the facilitation of exposed facets of Bi{sub 2}WO{sub 6} substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Long [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China); Wang, Yufei [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); Shen, Huidong; Zhang, Yu [School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China); Li, Jian [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); Wang, Danjun, E-mail: yulyanlong@aliyun.com [School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China)

    2017-01-30

    Highlights: • Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} hybrids with exposed (020) Bi{sub 2}WO{sub 6} facets have been synthesized. • X-ray photoelectron spectroscopy reveals that a small amount of Bi{sub 2}S{sub 3} was formed. • The enhanced photoactivity of hybrids is due to heterojunction and (020) facets. • A possible photocatalytic degradation mechanism is proposed. - Abstract: Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} hybrid architectures with exposed (020) Bi{sub 2}WO{sub 6} facets have been synthesized via a controlled anion exchange approach. X-ray photoelectron spectroscopy (XPS) reveals that a small amount of Bi{sub 2}S{sub 3} was formed on the surface of Bi{sub 2}WO{sub 6} during the anion exchange process, thus leading to the transformation from the Bi{sub 2}WO{sub 6} to Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}. A rhodamine B (RhB) aqueous solution was chosen as model organic pollutants to evaluate the photocatalytic activities of the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} catalysts. Under visible light irradiation, the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}-TAA displayed the excellent visible light photoactivities compared with pure Bi{sub 2}S{sub 3}, Bi{sub 2}WO{sub 6} and other composite photocatalysts. The efficient photocatalytic activity of the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}-TAA composite microspheres was ascribed to the constructed heterojunctions and the inner electric field caused by the exposed (020) Bi{sub 2}WO{sub 6} facets. Active species trapping experiments revealed that h{sup +} and O{sub 2}·{sup −} are the main active species in the photocatalytic process. Furthermore, the as-obtained photocatalysts showed good photocatalytic activity after four recycles. The results presented in this study provide a new concept for the rational design and development of highly efficient photocatalysts.

  17. Platinum coating of solution-spun Y sub 1 Ba sub 2 Cu sub 3 O sub x filament

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Tomoko; Niwa, Masato (Nagoya Inst. of Tech., Dept. of Materials Science and Engineering, Nagoya (Japan)); Kawanaka, Asaichi (Nitivy Co. Ltd., Shizuoka (Japan))

    1992-05-20

    Platinum coating of partially melted Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub x} filament produced by solution spinning is examined in order to enhance the J{sub c} of the filament. The filament was prepared by solution spinning through a homogeneous aqueous solution containing mixed acetates of Y, Ba and Cu, polyvinyl alcohol and organic acids. The heated filaments are dip-coated in aqueous solution of Pt chlorate. By controlling the melt-growth process of the filament, dense and highly oriented textures are produced and a maximum transport J{sub CT} of 36000 A/cm{sup 2} at 77 K and 0 T is achieved. The fiber axis of the filament appears to coincide with the direction perpendicular to the c-axis of the orthorhombic phase in the superconducting layer. The J{sub CT} of the filament is strongly dependent on the degree of crystal orientation. (orig.).

  18. Microstrucural characterization of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lopez, M.; Marin, P. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Madrid (Spain)

    2011-06-15

    Research highlights: > Two FeSi-base alloys as precursors for small dimension soft magnets. > Small particles rapidly solidified by gas atomisation. > Increase effective magnetic anisotropy constant by alloying segregation. > Magnetic hardenning due to volume decrease. - Abstract: Powder particles of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} soft magnetic alloys have been prepared by gas atomization. The gas atomized powder was microstructurally characterized and the dependence of coercivity with the composition and powder particle size investigated. As-atomized powder particles of both compositions were constituted by a bcc {alpha}-Fe (Si) solid solution. The Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles presented a grain microstructure with dendrite structure, which dendrite arms were enriched in Nb. The coercivity increased as the particle size decreased, with a minimum coercivity, of 5 Oe, measured in the Fe{sub 97}Si{sub 3} alloy in the range of 50-100 {mu}m powder particle size. The coercive fields were quite higher in the Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} than in the Fe{sub 97}Si{sub 3} powder, due to the Nb addition, which produced a phase segregation that leads to a noticeable magnetic hardening.

  19. Fundamental Understanding of Methane-Carbon Dioxide-Water (CH<sub>4sub>-CO>2sub>-H>2sub>O) Interactions in Shale Nanopores under Reservoir Conditions. Quarterly Report.

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yifeng [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-27

    This project focuses on the systematic study of CH<sub>4sub>-CO>2sub>-H>2sub>O interactions in shale nanopores under high-pressure and high temperature reservoir conditions. The proposed work will help to develop new stimulation strategies to enable efficient resource recovery from fewer and less environmentally impactful wells.

  20. Electrochemical reduction of Ag <sub>2sub> VP <sub>2sub> O <sub>8sub> composite electrodes visualized via in situ energy dispersive X-ray diffraction (EDXRD): unexpected conductive additive effects

    Energy Technology Data Exchange (ETDEWEB)

    Kirshenbaum, Kevin C. [Energy Sciences Directorate; Brookhaven National Laboratory; Upton, USA; Bock, David C. [Department of Chemistry; Stony Brook University; Stony Brook, USA; Zhong, Zhong [Energy Sciences Directorate; Brookhaven National Laboratory; Upton, USA; Marschilok, Amy C. [Department of Chemistry; Stony Brook University; Stony Brook, USA; Department of Materials Science and Engineering; Stony Brook University; Takeuchi, Kenneth J. [Department of Chemistry; Stony Brook University; Stony Brook, USA; Department of Materials Science and Engineering; Stony Brook University; Takeuchi, Esther S. [Energy Sciences Directorate; Brookhaven National Laboratory; Upton, USA; Department of Chemistry; Stony Brook University

    2015-01-01

    EDXRD of Li/C-Ag<sub>2sub>VP>2sub>O>8sub>revealed that higher-rate initial discharge (B) generated a more effective conductive matrixvia in situreduction-displacement-deposition of Ag0.

  1. Magnetic ordering induced by interladder coupling in the spin-1/2 Heisenberg two-leg ladder antiferromagnet C<sub>9sub>H>18sub>N>2sub>CuBr>4sub>

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Tao [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Schmidt, K. P. [Technische Universitat Dortmund, Dortmund (Germany); Coester, K. [Technische Universitat Dortmund, Dortmund (Germany); Awwadi, F. F. [The University of Jordan, Amman (Jordan); Turnbull, M. M. [Clark Univ., Worcester, MA (United States); Qiu, Y. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States); Rodriguez-Rivera, J. A. [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States); Zhu, M. [Michigan State Univ., East Lansing, MI (United States); Ke, X. [Michigan State Univ., East Lansing, MI (United States); Aoyama, C. P. [Univ. of Florida, Gainesville, FL (United States); Takano, Y. [Univ. of Florida, Gainesville, FL (United States); Cao, Huibo [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tian, Wei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ma, Jie [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Custelcean, Radu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhou, H. D. [Univ. of Tennessee, Knoxville, TN (United States); Matsuda, Masaaki [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-05-30

    In this article, we present specific-heat and neutron-scattering results for the S=1/2 quantum antiferromagnet (dimethylammonium)(3,5-dimethylpyridinium)CuBr<sub>4sub>. The material orders magnetically at T<sub>N>=1.99(2) K, and magnetic excitations are accompanied by an energy gap of 0.30(2) meV due to spin anisotropy. The system is best described as coupled two-leg spin-1/2 ladders with the leg exchange J<sub>leg>=0.60(2) meV, rung exchange J<sub>rung>=0.64(9) meV, interladder exchange J<sub>int>=0.19(2) meV, and an interaction-anisotropy parameter λ=0.93(2), according to inelastic neutron-scattering measurements. In contrast to most spin ladders reported to date, the material is a rare example in which the interladder coupling is very near the critical value required to drive the system to a Néel-ordered phase without the assistance of a magnetic field.

  2. Microwave dielectric properties of CaCu{sub 3}Ti{sub 4}O{sub 12}-Al{sub 2}O{sub 3} composite

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Mohd Fariz Ab; Abu, Mohamad Johari; Zaman, Rosyaini Afindi; Ahmad, Zainal Arifin [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Karim, Saniah Ab; Mohamed, Julie Juliewatty, E-mail: juliewatty.m@umk.edu.my [Advance Materials Research Cluster, Faculty of Earth Sciences, Universiti Malaysia Kelantan, Jeli Campus, 17600 Jeli, Kelantan (Malaysia); Ain, Mohd Fadzil [School of Electrical and Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2016-07-19

    (1-x)CaCu{sub 3}Ti{sub 4}O{sub 12} + (x)Al{sub 2}O{sub 3} composite (0 ≤ x ≤0.25) was prepared via conventional solid-state reaction method. The fabrication of sample was started with synthesizing stoichiometric CCTO from CaCO{sub 3}, CuO and TiO{sub 2} powders, then wet-mixed in deionized water for 24 h. The process was continued with calcined CCTO powder at 900 °C for 12 h before sintered at 1040 °C for 10 h. Next, the calcined CCTO powder with different amount of Al{sub 2}O{sub 3} were mixed for 24 h, then palletized and sintered at 1040 °C for 10. X-ray diffraction analysis on the sintered samples showed that CCTO powder was in a single phase, meanwhile the trace of secondary peaks which belong to CaAl{sub 2}O{sub 4} and Corundum (Al{sub 2}O{sub 3}) could be observed in the other samples Scanning electron microscopy analysis showed that the grain size of the sample is firstly increased with addition of Al{sub 2}O{sub 3} (x = 0.01), then become smaller with the x > 0.01. Microwave dielectric properties showed that the addition of Al{sub 2}O{sub 3} (x = 0.01) was remarkably reduced the dielectric loss while slightly increased the dielectric permittivity. However, further addition of Al{sub 2}O{sub 3} was reduced both dielectric loss and permittivity at least for an order of magnitude.

  3. Dynamics of CrO <sub>3sub> –Fe <sub>2sub> O <sub>3sub> Catalysts during the High-Temperature Water-Gas Shift Reaction: Molecular Structures and Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Keturakis, Christopher J.; Zhu, Minghui; Gibson, Emma K.; Daturi, Marco; Tao, Franklin; Frenkel, Anatoly I.; Wachs, Israel E.

    2016-06-13

    A series of supported CrO<sub>3sub>/Fe>2sub>O>3sub> catalysts were investigated for the high-temperature water-gas shift (WGS) and reverse-WGS reactions and extensively characterized using in situ and operando IR, Raman, and XAS spectroscopy during the high-temperature WGS/RWGS reactions. The in situ spectroscopy examinations reveal that the initial oxidized catalysts contain surface dioxo (O=)<sub>2sub>Cr6+O<sub>2sub> species and a bulk Fe<sub>2sub>O>3sub> phase containing some Cr3+ substituted into the iron oxide bulk lattice. Operando spectroscopy studies during the high-temperature WGS/RWGS reactions show that the catalyst transforms during the reaction. The crystalline Fe<sub>2sub>O>3sub> bulk phase becomes Fe<sub>3sub>O>4sub> ,and surface dioxo (O=)<sub>2sub>Cr6+O<sub>2sub> species are reduced and mostly dissolve into the iron oxide bulk lattice. Consequently, the chromium–iron oxide catalyst surface is dominated by FeO<sub>x> sites, but some minor reduced surface chromia sites are also retained. The Fe<sub>3–-xsub>CrxO>4sub> solid solution stabilizes the iron oxide phase from reducing to metallic Fe0 and imparts an enhanced surface area to the catalyst. Isotopic exchange studies with C16O<sub>2sub>/H>2sub> → C18O<sub>2sub>/H>2sub> isotopic switch directly show that the RWGS reaction proceeds via the redox mechanism and only O* sites from the surface region of the chromium–iron oxide catalysts are involved in the RWGS reaction. The number of redox O* sites was quantitatively determined with the isotope exchange measurements under appropriate WGS conditions and demonstrated that previous methods have undercounted the number of sites by nearly 1 order of magnitude. The TOF values suggest that only the redox O* sites affiliated with iron oxide are catalytic active sites for WGS/RWGS, though a carbonate oxygen

  4. A neutron diffraction study of the superionic transition in (Ca sub 1 sub - sub x Y sub x)F sub 2 sub + sub x with x=0.06

    CERN Document Server

    Hofmann, M; Wilson, C C; McIntyre, G J

    1997-01-01

    We have investigated the high-temperature superionic transition of the anion-excess fluorite (Ca sub 1 sub - sub x Y sub x)F sub 2 sub + sub x with x=0.06 using both monochromatic and time-of-flight Laue single-crystal neutron diffraction. The measured Bragg intensities indicate that the cuboctahedral defect clusters found at ambient temperature start to break up into smaller fragments even below the superionic transition temperature, T sub c approx 1200 K. Information concerning the local defect configuration at T = 1173 K has been provided by modelling the measured distribution of the coherent elastic diffuse scattering within the (11-bar0) plane of reciprocal space. The high-temperature defects are of the 'Willis' type and strongly resemble the short-lived Frenkel clusters found in the pure fluorites such as CaF sub 2 above T sub c. (author)

  5. Magnetic entropy change of a rare earth garnet (Gd{sub 0.5}Dy{sub 0.5}){sub 3}(Ga{sub 0.875}Fe{sub 0.125}){sub 5}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Koichi; Okano, Takahiro; Matsuzaki, Ayumi; Kamiya, Koji; Numazawa, Takenori

    2003-05-01

    The working refrigerant in magnetic refrigerators has been Gd{sub 3}Ga{sub 5}O{sub 12} (GGG) in the temperature range from 1 to 15 K. It has been shown that substitution of Ga for Fe in GGG can make entropy change large in high-temperature region. In order to increase the entropy change with small magnetic field, substitution of Gd for Dy is expected to be useful because of larger g-factor of Dy than Gd. The magnetization of (Gd{sub 0.5}Dy{sub 0.5}){sub 3}(Ga{sub 0.875}Fe{sub 0.125}){sub 5}O{sub 12} (GDGIG) was measured and the entropy change was calculated. This compound had larger entropy change with small magnetic field than that without Dy, though the absolute entropy change at low temperatures with large applied field was smaller due to the ground state doublet of Dy.

  6. Thermodynamic study of BaCuO[sub 2] and BaCu[sub 2]O[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Shimpo, Ryokichi; Nakamura, Yasushi (Univ. of Tokyo (Japan). Faculty of Engineering)

    1994-06-01

    The Gibbs energy changes for the syntheses of the interceramic compounds of BaCuO[sub 2] and BaCu[sub 2]O[sub 2] were investigated as a basic study in the Y-Ba-Cu-O system that includes a superconductor, YBa[sub 2]Cu[sub 3]O[sub 6.5+x]. For the compound BaCuO[sub 2], thermogravimetry with CO[sub 2[minus

  7. Magnetochemistry of the tetrahaloferrate(III) ions. 2. Crystal structure and magnetic ordering in (4-Br(py)H) sub 3 Fe sub 2 Cl sub 1. 3 Br sub 7. 7 and (4-Cl(py)H) sub 3 Fe sub 2 Br sub 9. The superexchange paths in the A sub 3 Fe sub 2 X sub 9 salts

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, C.B.; Carlin, R.L.; Schultz, A.J.; Loong, C.K. (Univ. of Illinois, Chicago (USA) Argonne National Lab., IL (USA))

    1990-09-05

    A series of neutron diffraction investigations at 25 K are reported on single crystals of stoichiometry (4-chloropyridinium){sub 3}Fe{sub 2}Br{sub 9} and on (4-bromopyridinium){sub 3}Fe{sub 2}Cl{sub 1.3}Br{sub 7.7}. The compound of stoichiometry (4-bromopyridinium){sub 3}Fe{sub 2}Cl{sub 1.3}Br{sub 7.7} is found to belong to the space group P2{sub 1}/n with four formula units in the unit cell, and the related compound (4-chloropyridinium){sub 3}Fe{sub 2}Bn{sub 9} was found to belong to the same space groups. Structural analysis shows that the iron is present as the (FeX{sub 4}){sup {minus}} ion (X = Cl, Br). The results of the determination of the crystal structure of the compounds are reported. Both materials are isomorphous with the previously reported bis(4-chloropyridinium tetrachloroferrate(III))-4-chloropyridinium chloride. Magnetic measurements on single crystals show that the S = 5/2 material (4-bromopyridinium){sub 3}Fe{sub 2}Cl{sub 1.3}Br{sub 7.7} orders as a canted antiferromagnet at 5.67 K, while (4-chloropyridinium){sub 3}Fe{sub 2}Br{sub 9} orders in a similar fashion at 7.96 K. Magnetic susceptibility data are compared with the theoretical predictions for the simple cubic (sc) Heisenberg high-temperature series expansion model, and superexchange pathways for the isostructural series of monoclinic A{sub 3}Fe{sub 2}X{sub 9} salts are examined. 19 refs., 6 figs., 6 tabs.

  8. Synthesis and characterization of Cu{sub 3}TaIn{sub 3}Se{sub 7} and CuTa{sub 2}InTe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, E.; Munoz-Pinto, M.; Duran-Pina, S.; Quintero, M.; Quintero, E.; Morocoima, M. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Romero, H. [Laboratorio de Magnetismo, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Briceno, J.M.; Fernandez, J. [Laboratorio de Analisis Quimico y Estructural (LAQUEM), Departamento de Fisica, Facultad de Ciencias, Merida (Venezuela); Grima-Gallardo, P.

    2008-07-15

    Polycrystalline samples of Cu{sub 3}TaIn{sub 3}Se{sub 7} and CuTa{sub 2}InTe{sub 4} were synthesized by the usual melt and anneal technique. X-ray powder diffraction showed a single phase behavior for both samples with tetragonal symmetry and unit cell parameter values a=5.794{+-}0.002 A, c=11.66{+-}0.01 A, c/a=2.01, V=391{+-}1 A{sup 3} and a=6.193{+-}0.001 A, c=12.400 {+-}0.002A, c/a=2.00, V=475{+-}1 A{sup 3}, respectively. Differential thermal analysis (DTA) measurements suggested a complicated behavior near the melting point with several thermal transitions observed in the heating and cooling runs. From the shape of the DTA peaks it was deduced that the melting is incongruent for both materials. Magnetic susceptibility measurements (zero-field cooling and field cooling) indicated an antiferromagnetic character with transition temperatures of T=70 K (Cu{sub 3}TaIn{sub 3}Se{sub 7}) and 42 K (CuTa{sub 2}InTe{sub 4}). A spin-glass transition was observed in Cu{sub 3}TaIn{sub 3}Se{sub 7} with T{sub f}{approx}50 K. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Synthesis, characterization, phase diagrams and superconducting and normal state magnetic properties of La<sub>2-xsub>SrxCuO>4sub> (0 ≤ x ≤ 0.08) and electrochemically oxidized La<sub>2-xsub>SrxCuO>4+δsub> (0 ≤ x ≤ 0.33, 0 ≤ δ ≤ 0.12)

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Fangcheng [Iowa State Univ., Ames, IA (United States)

    1993-08-01

    La<sub>2-xsub>SrxCuO>4sub> (0 ≤ x ≤ 0.15) can all be intercalated with oxygen by a novel electrochemical oxidation method. Bulk superconductivity is found with an onset T<sub>c>~ 40 K for the whole range 0.01 ≤ x ≤ 0.15; for x = 0.25 and 0.33, the electrochemical oxidation did not improve the superconducting properties. The magnetic susceptibility χ(T = 50--320 K) data for La<sub>2sub>CuO>4.11sub> and La<sub>1.92sub>Sr>0.08sub>CuO>4.07sub> are nearly identical with those of conventionally prepared La<sub>1.85sub>Sr>0.15sub>CuO>4sub>, indicating that the hole doping level (p) in the CuO<sub>2sub> planes of the three compounds is nearly the same. Combined thermogravimetric analysis and iodometric titration experiments indicate that part of the intercalated oxygen has a formal valence close to -1. The maximum doped-hole concentration in the CuO<sub>2sub> planes that can be achieved from combined Sr-doping and electrochemical oxygen doping for 0 ≤ x ≤ 0.15 is p ~ 0.16 holes/formula unit. Oxygen can also intercalate into single crystal La<sub>2sub>CuO>4sub> through a slow electrochemical oxidation process. The required low current and long time for the charging process reflects that the oxygen intercalation for a single crystal is limited by its small specific surface area and long diffusion distance. The anisotropic superconducting, magnetic and transport properties are summarized and compared with those of polycrystalline La<sub>2sub>CuO>4+δsub> as well as of YBa<sub>2sub>Cu>3sub>O>7-δsub> and La<sub>2-xsub>SrxCuO>4sub> single crystals. The single crystal La<sub>2sub>CuO>4+δsub> has a maximum T<sub>c> ~ 40 K, which is lower than that (T<sub>c> ~ 42--45) of the corresponding polycrystalline samples. The magnetic phase diagram of La<sub>2-xsub>SrxCuO>4sub> in the antiferromagnetic (AF) regime (0 ≤ x ≤ 0

  10. Photocatalytic decomposition of N{sub 2}O over TiO{sub 2}/g-C{sub 3}N{sub 4} photocatalysts heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Kočí, K., E-mail: kamila.koci@vsb.cz [Institute of Environmental technologies, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic); Reli, M.; Troppová, I.; Šihor, M. [Institute of Environmental technologies, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic); Kupková, J. [Nanotechnology center, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic); Kustrowski, P. [Faculty of Chemistry, Jagiellonian University in Kraków, ul. Ingardena 3, 30-060 Kraków (Poland); Praus, P. [Institute of Environmental technologies, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic); Department of Chemistry, VŠB Technical University of Ostrava 17. listopadu 15/2172, 708 00 Ostrava (Czech Republic)

    2017-02-28

    Highlights: • TiO{sub 2}/g-C{sub 3}N{sub 4} photocatalysts with the various TiO{sub 2}/g-C{sub 3}N{sub 4} weight ratios. • N{sub 2}O photocatalytic decomposition under UVC and UVA irradiation. • Heterojunction on the TiO{sub 2}/g-C{sub 3}N{sub 4} interface play an important role. • Optimal ratio of TiO{sub 2}:g-C{sub 3}N{sub 4} was 1:2 for the highest activity at UVA irradiation. - Abstract: TiO{sub 2}/g-C{sub 3}N{sub 4} photocatalysts with the various TiO{sub 2}/g-C{sub 3}N{sub 4} weight ratios from 1:2 to 1:6 were fabricated by mechanical mixing in water suspension followed by calcination. Pure TiO{sub 2} was prepared by thermal hydrolysis and pure g-C{sub 3}N{sub 4} was prepared from commercial melamine by thermal annealing at 620 °C. All the nanocomposites were characterized by X-ray powder diffraction, UV–vis diffuse reflectance spectroscopy, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, photoelectrochemical measurements and nitrogen physisorption. The prepared mixtures along with pure TiO{sub 2} and g-C{sub 3}N{sub 4} were tested for the photocatalytic decomposition of nitrous oxide under UVC (λ = 254 nm), UVA (λ = 365 nm) and Vis (λ > 400 nm) irradiation. The TiO{sub 2}/g-C{sub 3}N{sub 4} nanocomposites showed moderate improvement compared to pure g-C{sub 3}N{sub 4} but pure TiO{sub 2} proved to be a better photocatalyst under UVC irradiation. However, under UVA irradiation conditions, the photocatalytic activity of TiO{sub 2}/g-C{sub 3}N{sub 4} (1:2) nanocomposite exhibited an increase compared to pure TiO{sub 2}. Nevertheless, further increase of g-C{sub 3}N{sub 4} amount leads/led to a decrease in reactivity. These results are suggesting the nanocomposite with the optimal weight ratio of TiO{sub 2} and g-C{sub 3}N{sub 4} have shifted absorption edge energy towards longer wavelengths and decreased the recombination rate of charge carriers compared to pure g-C{sub 3}N{sub 4}. This is

  11. Enhanced visible-light photoactivity of g-C{sub 3}N{sub 4} via Zn{sub 2}SnO{sub 4} modification

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lihong; Wang, Xiaoxing; Nong, Qingyan [Department of Materials Physics, Zhejiang Normal University, Jinhua 321004 (China); Lin, Hongjun [College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004 (China); Teng, Botao [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Zhang, Yuting [Department of Materials Physics, Zhejiang Normal University, Jinhua 321004 (China); Zhao, Leihong; Wu, Tinghua [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); He, Yiming, E-mail: hym@zjnu.cn [Department of Materials Physics, Zhejiang Normal University, Jinhua 321004 (China)

    2015-02-28

    Highlights: • Novel Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} composites are prepared via calcination of Zn{sub 2}SnO{sub 4} and melamine. • Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} composite degrades RhB 3.2 times faster than g-C{sub 3}N{sub 4}. • The synergetic effect of Zn{sub 2}SnO{sub 4} and g-C{sub 3}N{sub 4} is the origin of the high photoactivity. - Abstract: The objective of this research was to prepare, characterize and evaluate the photocatalytic activity of Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} composite in RhB degradation under visible light irradiation. The composite was synthesized by simple calcination of Zn{sub 2}SnO{sub 4}–melamine mixture, and was characterized by various techniques including Brunauer–Emmett–Teller method (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). Characterization results indicated that the decoration of Zn{sub 2}SnO{sub 4} on g-C{sub 3}N{sub 4} showed nearly no effect on its light absorption performance, but promoted the surface area of the composite, which benefited the adsorption of dyes and the subsequent photocatalytic process. However, more significant was the formation of hetero-junction structure between Zn{sub 2}SnO{sub 4} and g-C{sub 3}N{sub 4}, which efficiently promoted the separation of electron–hole pairs and enhanced the photocatalytic performance of Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4}. The optimal Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} photocatalyst showed a degradation rate of 0.038 min{sup −1}, which was 3.2 times higher than that of g-C{sub 3}N{sub 4}. In addition, the Zn{sub 2}SnO{sub 4}/g-C{sub 3}N{sub 4} composite shows high stability. ·O{sub 2}{sup −} and h{sup +} were the main reactive species.

  12. Magnetotransport, structural and optical characterization of p-type modulation doped heterostructures with high Ge content Si sub 1 sub - sub x Ge sub x channel grown by SS-MBE on Si sub 1 sub - sub y Ge sub y /Si(001) virtual substrates

    CERN Document Server

    Myronov, M

    2001-01-01

    sub 4 Ge sub 0 sub . sub 6 linearly graded VS and corresponds to 14855cm sup 2 centre dot V sup - sup 1 centre dot s sup - sup 1 (2.87 centre dot 10 sup 1 sup 2 cm sup - sup 2). The highest Hall mobility (at sheet carrier density) measured at 293K was observed for Si sub 0 sub . sub 2 Ge sub 0 sub . sub 8 /Si sub 0 sub . sub 6 sub 5 Ge sub 0 sub . sub 3 sub 5 heterostructure after FTA at 750C for 30min and corresponds to 1776cm sup 2 centre dot V sup - sup 1 centre dot s sup - sup 1 (2.37 centre dot 10 sup 1 sup 3 cm sup - sup 2). To extract the drift mobility and sheet carrier density of 2DHG at temperatures up to 300K, magnetotransport measurements in magnetic fields up to 11T were performed on several heterostructures. The data were analyzed by technique of Maximum-Entropy Mobility Spectrum Analysis. The highest drift mobility (at sheet carrier density) of 2DHG at 290K was obtained for the Si sub 0 sub . sub 2 Ge sub 0 sub . sub 8 /Si sub 0 sub . sub 6 sub 5 Ge sub 0 sub . sub 3 sub 5 heterostructure after...

  13. Magnetic, electric and electron magnetic resonance properties of orthorhombic self-doped La sub 1 sub - sub x MnO sub 3 single crystals

    CERN Document Server

    Markovich, V; Shames, A I; Puzniak, R; Rozenberg, E; Yuzhelevski, Y; Mogilyansky, D; Wisniewski, A; Mukovskii, Y M; Gorodetsky, G

    2003-01-01

    The effect of lanthanum deficiency on structural, magnetic, transport, and electron magnetic resonance (EMR) properties has been studied in a series of La sub 1 sub - sub x MnO sub 3 (x = 0.01, 0.05, 0.11, 0.13) single crystals. The x-ray diffraction study results for the crystals were found to be compatible with a single phase of orthorhombic symmetry. The magnetization curves exhibit weak ferromagnetism for all samples below 138 K. It was found that both the spontaneous magnetization and the coercive field increase linearly with x. The pressure coefficient dT sub N /dP decreases linearly with self-doping, from a value of 0.68 K kbar sup - sup 1 for La sub 0 sub . sub 9 sub 9 MnO sub 3 to 0.33 K kbar sup - sup 1 for La sub 0 sub . sub 8 sub 7 MnO sub 3. The resistivity of low-doped La sub 0 sub . sub 9 sub 9 MnO sub 3 crystal is of semiconducting character, while that of La sub 0 sub . sub 8 sub 7 MnO sub 3 depends weakly on temperature between 180 and 210 K. It was found that the magnetic and transport prop...

  14. CO{sub 2} separation

    Energy Technology Data Exchange (ETDEWEB)

    Hakuta, Toshikatu [National Inst. of Materials and Chemical Research, Ibaraki (Japan)

    1993-12-31

    The climate change induced by CO{sub 2} and other greenhouse gases is probably the most serious environmental threat that mankind has ever experienced. Nowadays fossil fuels occupy the majority of the world commercial energy supply. Most nations will be dependent on fossil fuels even in the first half of the next century. Around 30 % of CO{sub 2} in the world is emitted from thermal power plants. Recovering CO{sub 2} from energy conversion processes and storing it outside the atmosphere is a promising option for the mitigation of global warming. CO{sub 2} fixation and storage include CO{sub 2} disposal into oceans and underground, and utilization of CO{sub 2}. CO{sub 2} separation process will be used in any CO{sub 2} storage system, and is estimated to consume almost half the energy of the total system. Research and development of highly efficient CO{sub 2} separation process is most important from the viewpoint of practical application of CO{sub 2} fixation system.

  15. Tuning of Thermal Stability in Layered Li(Ni <sub>x> Mn <sub>y> Co <sub>z> )O <sub>2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jiaxin; Liu, Tongchao; Hu, Zongxiang; Wei, Yi; Song, Xiaohe; Ren, Yang; Wang, Weidong; Rao, Mumin; Lin, Yuan; Chen, Zonghai; Lu, Jun; Wang, Chongmin; Amine, Khalil; Pan, Feng

    2016-09-19

    Understanding and further designing new layered Li(Ni<sub>xsub>Mn<sub>yCoz)O>2sub> (NMC) (x + y + z = 1) materials with optimized thermal stability is important to rechargeable Li batteries (LIBs) for electrical vehicles (EV). Using ab initio calculations combined with experiments, we clarified how the thermal stability of NMC materials can be tuned by the most unstable oxygen, which is determined by the local coordination structure unit (LCSU) of oxygen (TM(Ni, Mn, Co)<sub>3sub>-O-Li>3-x'sub>): each O atom bonds with three transition metals (TM) from the TM-layer and three to zero Li from fully discharged to charged states from the Li-layer. Under this model, how the lithium content, valence states of Ni, contents of Ni, Mn, and Co, and Ni/Li disorder to tune the thermal stability of NMC materials by affecting the sites, content, and the release temperature of the most unstable oxygen is proposed. The synergistic effect between Li vacancies and raised valence state of Ni during delithiation process can aggravate instability of oxygen, and oxygen coordinated with more nickel (especially with high valence state) in LSCU becomes more unstable at a fixed delithiation state. The Ni/Li mixing would decrease the thermal stability of the “NiMn” group NMC materials but benefit the thermal stability of “Ni-rich” group, because the Ni in the Li layer would form 180° Ni-O-Ni super exchange chains in “Ni-rich” NMC materials. Mn and Co doping can tune the initial valence state of Ni, local coordination environment of oxygen, and the Ni/Li disorder, thus to tune the thermal stability directly.

  16. Identifying the Distribution of Al 3+ in LiNi <sub>0.8sub> Co <sub>0.15sub> Al <sub>0.05sub> O <sub>2sub>

    Energy Technology Data Exchange (ETDEWEB)

    Trease, Nicole M.; Seymour, Ieuan D.; Radin, Maxwell D.; Liu, Haodong; Liu, Hao; Hy, Sunny; Chernova, Natalya; Parikh, Pritesh; Devaraj, Arun; Wiaderek, Kamila M.; Chupas, Peter J.; Chapman, Karena W.; Whittingham, M. Stanley; Meng, Ying Shirley; Van der Van, Anton; Grey, Clare P.

    2016-11-22

    The doping of Al into layered Li transition metal (TM) oxide cathode materials, LiTMO<sub>2sub>, is known to improve the structural and thermal stability, although the origin of the enhanced properties is not well understood. The effect of aluminum doping on layer stabilization has been investigated using a combination of techniques to measure the aluminum distribution in layered LiNi<sub>0.8sub>Co>0.15sub>Al>0.05sub>O>2sub> (NCA) over multiple length scales with 27Al and 7Li MAS NMR, local electrode atom probe (APT) tomography, X-ray and neutron diffraction, DFT, and SQUID magnetic susceptibility measurements. APT ion maps show a homogenous distribution of Ni, Co, Al and O<sub>2sub> throughout the structure at the single particle level in agreement with the high-temperature phase diagram. 7Li and 27Al NMR indicates that the Ni3+ ions undergo a dynamic Jahn-Teller (JT) distortion. 27Al NMR spectra indicate that the Al reduces the strain associated with the JT distortion, by preferential electronic ordering of the JT long bonds directed toward the Al3+ ion. The ability to understand the complex atomic and orbital ordering around Al3+ demonstrated in the current method will be useful for studying the local environment of Al3+ in a range of transition metal oxide battery materials.

  17. Al{sub 2}O{sub 3} reinforced nanoparticle ZrO{sub 2} (3at%?Y{sub 2}O{sub 3}); Al{sub 2}O{sub 3} reforcado com nanoparticulas de ZrO{sub 2}(3%mol Y{sub 2}O{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Cossu, C.M.F.A.; Alves, M.F.R.P.; Campos, L.Q.B.; Magnago, R.O.; Santos, C., E-mail: caio.cossu@usp.br [Universidade do Estado do Rio de Janeiro (UERJ), Resende, RJ (Brazil). Faculdade de Tecnologia; Simba, B.G. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Guaratingueta, SP (Brazil). Faculdade de Engenharia

    2016-07-01

    This work developed a composite Al{sub 2}O{sub 3}-based reinforced with nanoparticles of ZrO{sub 2} (Y{sub 2}O{sub 3}), to evaluate the effect of the content of ZrO{sub 2} nanoparticles (Y{sub 2}O{sub 3}) on the mechanical properties. Mixtures containing a matrix of Al{sub 2}O{sub 3} with fractions in weight of 3%, 5%, 10% and 15%, ZrO{sub 2} (Y{sub 2}O{sub 3}), and were mixed in mortar mill. Mixtures received 5% polymeric binder (PVA); and after adding the binder, the material was pressed uniaxially to 50MPa, and then sintered at a temperature of 1600 ° C - 2h. The sintered products were characterized by X-ray diffraction, scanning electron microscopy (SEM), relative density, hardness and fracture toughness. The results of X-ray diffraction showed that Al{sub 2}O{sub 3} and tetragonal ZrO{sub 2} as crystal phases found after sintering. Furthermore, the relative green density of 55% was predominant in the compact; and after sintering, varied depending on the ZrO{sub 2} content, reaching 97% in sintered compositions with 3% ZrO{sub 2} nanoparticles (Y{sub 2O}3). The hardness of the samples showed values of 1670HV and the maximum toughness of 3.2 MPa × m{sup 1/2}, directly influenced by the presence of nanoparticles ZrO{sub 2} uniformly dispersed in the matrix Al{sub 2}O{sub 3}, which results in at least two main mechanisms tenacifiers: transformation of tetragonal-monoclinic phase of zirconia, and compressive residual strain between the two phases present, Al{sub 2}O{sub 3} and tetragonal ZrO{sub 2}. (author)

  18. Thermodynamic study of LiF-BeF{sub 2}-ZrF{sub 4}-UF{sub 4} system

    Energy Technology Data Exchange (ETDEWEB)

    Benes, O. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany)], E-mail: ondrej.benes@cec.eu.int; Konings, R.J.M. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany)

    2008-03-06

    In this work the three binary phase diagrams LiF-ZrF{sub 4}, BeF{sub 2}-ZrF{sub 4} and UF{sub 4}-ZrF{sub 4} were thermodynamically assessed. The three ternary phase diagrams LiF-BeF{sub 2}-ZrF{sub 4}, BeF{sub 2}-ZrF{sub 4}-UF{sub 4} and LiF-ZrF{sub 4}-UF{sub 4} were approximated on the basis of binary data. A pseudo-ternary LiF-BeF{sub 2}-ZrF{sub 4} system with constant amount of UF{sub 4} set to 0.83 mol% was calculated as well, typical for molten salt reactor fuel. Based on this diagram a suggestion for the composition of the fuel in this system was made.

  19. Interfacial Electron Transfer Dynamics Following Laser Flash Photolysis of [Ru(bpy)<sub>2sub>((4,4'-PO<sub>3sub>H>2sub>)>2sub>bpy)]2+ in TiO<sub>2 sub>Nanoparticle Films in Aqueous Environments

    Energy Technology Data Exchange (ETDEWEB)

    Brennaman, Kyle M. [Univ. of North Carolina, Chapel Hill, NC (United States); Patrocinio, Antonio O.T. [Universidade de Sao Paulo (Brazil); Song, Wenjing [Univ. of North Carolina, Chapel Hill, NC (United States); Jurss, Jonah W. [Univ. of North Carolina, Chapel Hill, NC (United States); Concepcion, Javier J. [Univ. of North Carolina, Chapel Hill, NC (United States); Hoertz, Paul G. [RTI International, Research Triangle Park, NC (United States); Traub, Matthew C. [Univ. of North Carolina, Chapel Hill, NC (United States); Murakami Iha, Neyde Y. [Universidade de Sao Paulo (Brazil); Meyer, Thomas J. [Univ. of North Carolina, Chapel Hill, NC (United States)

    2011-02-16

    Nanosecond laser flash photolysis has been used to investigate injection and back electron transfer from the complex [(Ru(bpy)<sub>2sub>(4,4'-(PO<sub>3sub>H>2sub>)>2sub>bpy)]2+ surface-bound to TiO<sub>2sub> (TiO2-RuII). The measurements were conducted under conditions appropriate for water oxidation catalysis by known single-site water oxidation catalysts. Systematic variations in average lifetimes for back electron transfer, <τ<sub>bet>>, were observed with changes in pH, surface coverage, incident excitation intensity, and applied bias. The results were qualitatively consistent with a model involving rate-limiting thermal activation of injected electrons from trap sites to the conduction band or shallow trap sites followed by site-to-site hopping and interfacial electron transfer, TiO<sub>2sub>(e-)-Ru3+→TiO<sub>2sub>-Ru2+. The appearance of pH-dependent decreases in the efficiency of formation of TiO<sub>2sub>-Ru3+ and in incident-photon-to-current efficiencies with the added reductive scavenger hydroquinone point to pH-dependent back electron transfer processes on both the sub-nanosecond and millisecond–microsecond time scales, which could be significant in limiting long-term storage of multiple redox equivalents.

  20. Photoemission Study of the Rare Earth Intermetallic Compounds: RNi<sub>2sub>Ge>2sub> (R=Eu, Gd)

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jongik [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    EuNi<sub>2sub>Ge>2sub> and GdNi<sub>2sub>Ge>2sub> are two members of the RT<sub>2sub>X>2sub> (R = rare earth, T = transition metal and X = Si, Ge) family of intermetallic compounds, which has been studied since the early 1980s. These ternary rare-earth intermetallic compounds with the tetragonal ThCr<sub>2sub>Si>2sub> structure are known for their wide variety of magnetic properties, Extensive studies of the RT<sub>2sub>X>2sub> series can be found in Refs [ 1,2,3]. The magnetic properties of the rare-earth nickel germanides RNi<sub>2sub>Ge>2sub> were recently studied in more detail [4]. The purpose of this dissertation is to investigate the electronic structure (both valence band and shallow core levels) of single crystals of EuNi<sub>2sub>Ge>2sub> and GdNi<sub>2sub>Ge>2sub> and to check the assumptions that the f electrons are non-interacting and, consequently, the rigid-band model for these crystals would work [11], using synchrotron radiation because, to the best of our knowledge, no photoemission measurements on those have been reported. Photoemission spectroscopy has been widely used to study the detailed electronic structure of metals and alloys, and especially angle-resolved photoemission spectroscopy (ARPES) has proven to be a powerful technique for investigating Fermi surfaces (FSs) of single-crystal compounds.

  1. M<sub>5sub>Si>3sub>(M=Ti, Nb, Mo) Based Transition-Metal Silicides for High Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhihong [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    Transition metal silicides are being considered for future engine turbine components at temperatures up to 1600 C. Although significant improvement in high temperature strength, room temperature fracture toughness has been realized in the past decade, further improvement in oxidation resistance is needed. Oxidation mechanism of Ti<sub>5sub>Si>3sub>-based alloys was investigated. Oxidation behavior of Ti<sub>5sub>Si>3sub>-based alloy strongly depends on the atmosphere. Presence of Nitrogen alters the oxidation behavior of Ti<sub>5sub>Si>3sub> by nucleation and growth of nitride subscale. Ti<sub>5sub>Si>3.2sub>and Ti<sub>5sub>Si>3sub>C>0.5sub> alloys exhibited an excellent oxidation resistance in nitrogen bearing atmosphere due to limited dissolution of nitrogen and increased Si/Ti activity ratio. MoSi<sub>2sub> coating developed by pack cementation to protect Mo-based Mo-Si-B composites was found to be effective up to 1500 C. Shifting coating composition to T1+T2+Mo<sub>3sub>Si region showed the possibility to extend the coating lifetime above 1500 C by more than ten times via formation of slow growing Mo<sub>3sub>Si or T2 interlayer without sacrificing the oxidation resistance of the coating. The phase equilibria in the Nb-rich portion of Nb-B system has been evaluated experimentally using metallographic analysis and differential thermal analyzer (DTA). It was shown that Nb<sub>ss> (solid solution) and NbB are the only two primary phases in the 0-40 at.% B composition range, and the eutectic reaction L {leftrightarrow} Nb<sub>SS> + NbB was determined to occur at 2104 ± 5 C by DTA.

  2. Synthesis, crystal structure and infrared spectroscopy of a new non-centrosymmetric mixed-anion phosphate Na{sub 4}Mg{sub 3}(PO{sub 4}){sub 2}(P{sub 2}O{sub 7})

    Energy Technology Data Exchange (ETDEWEB)

    Essehli, Rachid, E-mail: essehli_rachid@yahoo.f [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, P.O. Box 717, 60000 Oujda (Morocco); El Bali, Brahim [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, P.O. Box 717, 60000 Oujda (Morocco); Benmokhtar, Said [LCMS, Department of Chemistry, Faculty of Sciences Ben M' SIK, Casablanca (Morocco); Fuess, Hartmut; Svoboda, Ingrid [Materials Science, Darmstadt University of Technology, Petersenstr. 23, D-64287 Darmstadt (Germany); Obbade, Said [Equipe de Chimie du Solide, UCCS - UMR CNRS 8181, USTL-ENSCL, B.P. 90108, 59652 Villeneuve d' Ascq Cedex (France)

    2010-03-18

    The new mixed-anion phosphate Na{sub 4}Mg{sub 3}(PO{sub 4}){sub 2}(P{sub 2}O{sub 7}) has been prepared and its structure has been determined by single crystal X-ray diffraction. The crystal structure was refined to R = 0.0290 (wR = 0.0836) for 1527 independent reflexions. This compound crystallizes in the orthorhombic non-centrosymmetric space group Pn2{sub 1}a with a = 17.985(2) A, b = 6.525(9) A, c = 10.511(1) A, and Z = 4. The framework is built up from [PO{sub 4}] tetrahedra, [P{sub 2}O{sub 7}] groups and [MgO{sub 6}] octahedra. The three dimensional structure consists of [Mg{sub 3}P{sub 2}O{sub 13}]{sub {infinity}} infinite layers parallel to the bc plane. The layers are built up from [MgO{sub 6}] octahedra and [PO{sub 4}] tetrahedral, they are connected along the a axis by O-P-O-P-O bridges of the diphosphate groups. Large tunnels extending along the three main crystallographic directions host four crystallographically distinct sodium cations. The infrared spectrum of Na{sub 4}Mg{sub 3}(PO{sub 4}){sub 2}(P{sub 2}O{sub 7}) is interpreted on the basis of P{sub 2}O{sub 7}{sup 4-} and PO{sub 4}{sup 3-} vibrations. The appearance of {nu}{sub s}P-O-P in the spectrum suggests a bent P-O-P bridge for the P{sub 2}O{sub 7}{sup 4-} ions in the compound, which is in agreement with the X-ray data.

  3. Crystal structures and magnetic properties of iron (III)-based phosphates: Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Essehli, Rachid, E-mail: rachid_essehli@yahoo.fr [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Bali, Brahim El [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Benmokhtar, Said [LCMS, Laboratoire de Chimie des Materiaux Solides, Departement de chimie, Faculte des Sciences Ben M' SIK, Casablanca (Morocco); Bouziane, Khalid [Physics Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123 Al Khod, Sultanate of Oman (Oman); Manoun, Bouchaib [Laboratoire de Physico-Chimie des Materiaux, Departement de Chimie, FST Errachidia, University Moulay Ismail, B.P. 509 Boutalamine, Errachidia (Morocco); Abdalslam, Mouner Ahmed [Materials Science, Technical University Darmstadt, Darmstadt (Germany); Ehrenberg, Helmut [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2011-01-28

    Graphical abstract: A perspective view of the Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: > Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Magnetism behaviours of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Antiferromagnetism interactions. > Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na{sub 4}NiFe(PO{sub 4}){sub 3} (I) and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R{sub 1} = 0.041, wR{sub 2}=0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, {beta} = 113.66(4){sup o}, R{sub 1} = 0.043, wR{sub 2}=0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O{sub 6}] octahedra and [PO{sub 4}] tetrahedra forming [NiFe(PO{sub 4}){sub 3}]{sup 4+} units which align in chains along the c-axis. The Na{sup +} cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni{sub 2}O{sub 10}] units of edge-sharing [NiO{sub 6}] octahedra, which alternate with [FeO{sub 6}] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na{sup +}. The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The

  4. The Li–Si–(O)–N system revisited: Structural characterization of Li{sub 21}Si{sub 3}N{sub 11} and Li{sub 7}SiN{sub 3}O

    Energy Technology Data Exchange (ETDEWEB)

    Casas-Cabanas, M. [CIC energiGUNE, Parque Tecnológico de Álava, Albert Einstein 48, ED.CIC, 01510 Miñano (Spain); Santner, H. [Institut de Ciència de Materials de Barcelona (CSIC) Campus UAB, 08193 Bellaterra, Catalonia (Spain); Palacín, M.R., E-mail: rosa.palacin@icmab.es [Institut de Ciència de Materials de Barcelona (CSIC) Campus UAB, 08193 Bellaterra, Catalonia (Spain)

    2014-05-01

    A systematic study of the Li–Si–(O)–N system is presented. The synthetic conditions to prepare Li{sub 2}SiN{sub 2}, Li{sub 5}SiN{sub 3}, Li{sub 18}Si{sub 3}N{sub 10}, Li{sub 21}Si{sub 3}N{sub 11} and Li{sub 7}SiN{sub 3}O are described and the structure of the last two compounds has been solved for the first time. While Li{sub 21}Si{sub 3}N{sub 11} crystallizes as a superstructure of the anti-fluorite structure with Li and Si ordering, Li{sub 7}SiN{sub 3}O exhibits the anti-fluorite structure with both anion and cation disorder. - Graphical abstract: A systematic study of the Li–Si–(O)–N system is presented. Li{sub 21}Si{sub 3}N{sub 11} crystallizes as a superstructure of the anti-fluorite structure with Li and Si ordering, Li{sub 7}SiN{sub 3}O exhibits the anti-fluorite structure with both anion and cation disorder. - Highlights: • Li{sub 2}SiN{sub 2}, Li{sub 5}SiN{sub 3}, Li{sub 18}Si{sub 3}N{sub 10}, Li{sub 21}Si{sub 3}N{sub 11} and Li{sub 7}SiN{sub 3}O are prepared. • The structures of Li{sub 21}Si{sub 3}N{sub 11} and Li{sub 7}SiN{sub 3}O are presented. • Li{sub 21}Si{sub 3}N{sub 11} exhibits an anti-fluorite superstructure with Li and Si ordering.

  5. Synthesis, structural and magnetic properties of spin ladder compound Ca{sub 1-x}Co{sub x}Cu{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sekar, C., E-mail: Sekar2025@gmail.com [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003 (India); Department of Physics, Periyar University, Salem 636011 (India); Paulraj, S. [Department of Physics, Periyar University, Salem 636011 (India); Krabbes, G. [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden (Germany); Kanagaraj, M.; Arumugam, S. [Centre for High Pressure Research, Bharathidasan University, Trichy 620024 (India); Kumar, Ravhi S. [High Pressure Science and Engineering Centre and Department of Physics, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States)

    2011-12-15

    MCu{sub 2}O{sub 3} (M=Ca and Co) system has two-leg spin ladder structure similar to that of the prototype SrCu{sub 2}O{sub 3} system except that the rungs are buckled with an angle of 123{sup o} and 105{sup o} for CaCu{sub 2}O{sub 3} and CoCu{sub 2}O{sub 3} compounds, respectively. We have synthesized powder samples of (Ca{sub 1-x}Co{sub x})Cu{sub 2}O{sub 3} (x=0.00-1.00) by the solid state reaction method and their structural and magnetic properties have been investigated. All the synthesized compounds crystallize in orthorhombic structure with space group Pmmn. Lattice parameters of (Ca{sub 1-x}Co{sub x})Cu{sub 2}O{sub 3} decrease with the increase in Co content. DC magnetic susceptibility {chi}(T) results of the end products CaCu{sub 2}O{sub 3} and CoCu{sub 2}O{sub 3} show antiferromagnetic transition (T{sub N}) at 27 and 215 K, respectively. Co doping into (Ca{sub 1-x}Co{sub x})Cu{sub 2}O{sub 3} enhances its T{sub N} systematically with increasing Co concentration. The {chi}(T) of CoCu{sub 2}O{sub 3} shows a broad transition with the peak temperature around 215 K and it was found to be field independent up to 90 kOe. The ambiguity concerning the transition was ruled out by recording the temperature dependent X-ray diffraction pattern on CoCu{sub 2}O{sub 3} system, which indicated that there is no structural transition in the investigated temperature range of 115-300 K. Further, specific heat measurement on CoCu{sub 2}O{sub 3} confirms the magnetic phase transition by the appearance of a sharp peak at 215 K. - Highlights: > Powder sample of (Ca{sub 1-x}Co{sub x})Cu{sub 2}O{sub 3} (x=0.00-1.00) has been synthesized by the solid state reaction method for the first time. > DC magnetic susceptibility {chi}(T) results of CaCu{sub 2}O{sub 3} and CoCu{sub 2}O{sub 3} show antiferromagnetic shift (T{sub N}) at 27 and 215 K in that order. > {chi}(T) of CoCu{sub 2}O{sub 3} shows a broad transition with the peak temperature around 215 K.

  6. Structural transitions in Pb(In<sub>1/2sub>Nb>1/2sub>)O <sub>3sub> under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Ahart, Muhtar [Carnegie Inst. of Washington, Washington, DC (United States); Somayazulu, Maddury [Carnegie Inst. of Washington, Washington, DC (United States); Kojima, Seiji [Gifu Univ. (Japan); Yasuda, Naohiko [Gifu Univ. (Japan); Prosandeev, Sergey [Univ. of Arkansas, Fayetteville, AR (United States). Inst. for Nanoscience and Engineering; Hemley, Russell J. [Carnegie Inst. of Washington, Washington, DC (United States)

    2015-12-01

    Room-temperature Raman scattering and x-ray diffraction measurements together with first-principles calculations were employed to investigate the behavior of disordered Pb(In<sub>1/2sub>Nb>1/2sub>)O>3sub> (PIN) under pressure up to 50GPa. Raman spectra show broad bands but a peak near the 380cm-1 increases its intensity with pressure. The linewidth of the band at 550cm-1 also increases with pressure, while two of the Raman peaks merge above 6GPa. Above 16GPa, we observe additional splitting of the band at 50cm-1. The pressure evolution of the diffraction patterns for PIN shows obvious Bragg peaks splitting above 16GPa; consistent with a symmetry lowering transition. The transition at 0.5GPa is identified as a pseudo-cubic to orthorhombic (Pbam) structural change whereas the transition at 16GPa is isostructure and associated with changes in linear compressibility and octahedral titling, and the transition at 30GPa is associated to an orthorhombic to monoclinic change. First-principles calculations indicate that the Pbam structure is ground state with antiferrodisdortion consistent with experiment.

  7. Synchrotron X-ray diffuse scattering from a stable polymorphic material: terephthalic acid, C <sub>8sub> H <sub>6sub> O <sub>4sub>

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, D. J.; Chan, E. J.

    2017-01-31

    Terephthalic acid (TPA, C<sub>8sub>H>6sub>O>4sub>) is an industrially important chemical, one that shows polymorphism and disorder. Three polymorphs are known, two triclinic [(I) and (II)] and one monoclinic (III). Of the two triclinic polymorphs, (II) has been shown to be more stable in ambient conditions. This paper presents models of the local order of polymorphs (I) and (II), and compares the single-crystal diffuse scattering (SCDS) computed from the models with that observed from real crystals. TPA shows relatively weak and less-structured diffuse scattering than some other polymorphic materials, but it does appear that the SCDS is less well modelled by a purely harmonic model in polymorph (I) than in polymorph (II), according to the idea that the diffuse scattering is sensitive to anharmonicity that presages a structural phase transition. The work here verifies that displacive correlations are strong along the molecular chains and weak laterally, and that it is not necessary to allow the —COOH groups to librate to successfully model the diffuse scattering – keeping in mind that the data are from X-ray diffraction and not directly sensitive to H atoms.

  8. Crystal structures of KM(AsF{sub 6}){sub 3} (M{sup 2+} = Mg, Co, Mn, Zn), KCu(SbF{sub 6}){sub 3} and [Co(HF){sub 2}]Sr[Sr(HF)]{sub 2}-[Sr(HF){sub 2}]{sub 2}[AsF{sub 6}]{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Mazej, Zoran; Goreshnik, Evgeny [Jozef Stefan Institute, Ljubljana (Slovakia). Dept. of Inorganic Chemisrty and Technology

    2015-05-01

    The KM(AsF{sub 6}){sub 3} (M{sup 2+} = Mg, Co, Mn, Zn) and KCu(SbF{sub 6}){sub 3} compounds crystallize isotypically to previously known KNi(AsF{sub 6}){sub 3}. The main features of the structure of these compounds are rings of MF{sub 6} octahedra sharing apexes with AsF{sub 6} octahedra connected into infinite tri-dimensional frameworks. In this arrangement cavities are formed where K{sup +} cations are placed. Single crystals of CoSr{sub 5}(AsF{sub 6}){sub 12}.8HF were obtained as one of the products after the crystallization of 3KF/CoF{sub 2}/SrF{sub 2} mixture in the presence of AsF{sub 5} in anhydrous HF. The CoSr{sub 5}(AsF{sub 6}){sub 12}.8HF is monoclinic, C/2c (No.15), with a = 26.773(5) Aa, b = 10.087(2) Aa, c = 21.141(5) Aa, β = 93.296(13) {sup circle}, V = 5699.9(19) Aa{sup 3} at 200 K, and Z = 4. There are three crystallographically non-equivalent Sr{sup 2+} cations in the crystal structure of CoSr{sub 5}(AsF{sub 6}){sub 12}.8HF. The Sr1 is coordinated by ten fluorine atoms from eight different [AsF{sub 6}]- anions, meanwhile Sr2 and Sr3 are bound to nine fluorine atoms provided by one HF and eight AsF{sub 6} units or by two HF and six AsF{sub 6} units, respectively. The Co{sup 2+} is coordinated distorted-octahedrally by six fluorine atoms from two HF molecules and four different AsF{sub 6} units. All those moieties in the crystal structure of [Co(HF){sub 2}]Sr[Sr(HF)]{sub 2}[Sr(HF){sub 2}]{sub 2}[AsF{sub 6}]{sub 12} are connected into tridimensional framework. The CoSr{sub 5}(AsF{sub 6}){sub 12}.8HF is a unique example of compound where HF molecules are directly bound via fluorine atoms to two different metal centres.

  9. Isothermal sections of the quasi-ternary systems Ag{sub 2}S(Se)–Ga{sub 2}S(Se){sub 3}–In{sub 2}S(Se){sub 3} at 820 K and the physical properties of the ternary phases Ga{sub 5.5}In{sub 4.5}S{sub 15}, Ga{sub 6}In{sub 4}Se{sub 15} and Ga{sub 5.5}In{sub 4.5}S{sub 15}:Er{sup 3+}, Ga{sub 6}In{sub 4}Se{sub 15}:Er{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Ivashchenko, I.A., E-mail: Ivashchenko.Inna@eenu.edu.ua [Department of Inorganic and Physical Chemistry, Eastern European National University, Lutsk (Ukraine); Danyliuk, I.V.; Gulay, L.D. [Department of Ecology and Environmental Protection, Eastern European National University, Lutsk (Ukraine); Halyan, V.V. [Department of General Physics, Eastern European National University, Lutsk (Ukraine); Olekseyuk, I.D. [Department of Inorganic and Physical Chemistry, Eastern European National University, Lutsk (Ukraine)

    2016-05-15

    Isothermal sections of the quasi-ternary systems Ag{sub 2}S(Se)–Ga{sub 2}S(Se){sub 3}–In{sub 2}S(Se){sub 3} at 820 K were compared. Along the 50 mol% Ag{sub 2}S(Se), both systems feature continuous solid solutions with the chalcopyrite structure. Along the 17 mol% Ag{sub 2}S(Se), the interactions at the AgIn{sub 5}S(Se){sub 8}–'AgGa{sub 5}S(Se){sub 8}' sections are different. In the Ag{sub 2}S–Ga{sub 2}S{sub 3}–In{sub 2}S{sub 3} system the existence of the layered phase AgGa{sub x}In{sub 5–x}S{sub 8}, 2.25≤x≤2.85, was confirmed (S.G. P6{sub 3}mc). The Ag{sub 2}Se–Ga{sub 2}Se{sub 3}–In{sub 2}Se{sub 3} system features the formation of solid solution (up to 53 mol% Ga{sub 2}Se{sub 3}) based on AgIn{sub 5}Se{sub 8} (S.G. P-42m). Crystal structure, atomic coordinates were determined by powder diffraction method for samples from the homogeneity region of AgIn{sub 5}Se{sub 8}. Specific conductivities of the crystals Ga{sub 6}In{sub 4}Se{sub 15} (1.33·10{sup −6} Ω{sup −1} m{sup −1}), Ga{sub 5.94}In{sub 3.96}Er{sub 0.1}Se{sub 15} (3.17·10{sup −6} Ω{sup −1} m{sup −1}), Ga{sub 5.5}In{sub 4.5}S{sub 15} (7.94·10{sup −6} Ω{sup −1} m{sup −1}), Ga{sub 5.46}In{sub 4.47}Er{sub 0.07}S{sub 15} (1·10{sup −9} Ω{sup −1} m{sup −1}) were measured at room temperature. Optical absorption and photoconductivity spectra were recorded in the range 400–760 nm. The introduction of erbium leads to an increase in the absorption coefficient and to the appearance of absorption bands at 530, 660, 810, 980, 1530 nm. - Highlights: • Nature of solid solutions in Ag{sub 2}S(Se)–Ga{sub 2}S(Se){sub 3}–In{sub 2}S(Se){sub 3} (820 K) were discussed. • Crystal structures of ternary and quaternary compounds were discussed. • Specific conductivity, optical properties of four single crystals were measured. • Photoconductivity of the Ga{sub 5.5}In{sub 4.5}S{sub 15} in the range 400–760 nm were recorded.

  10. Optimizing Blue Persistent Luminescence in (Sr <sub>1-δsub> Ba <sub>δ> ) <sub>2sub> MgSi <sub>2sub> O <sub>7:sub> Eu 2+ ,Dy 3+ via Solid Solution for Use in Point-of-Care Diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Finley, Erin; Cobb, Angelica; Duke, Anna; Paterson, Andrew; Brgoch, Jakoah (Luminostics); (Houston)

    2016-11-04

    Inorganic persistent luminescent phosphors are an excellent class of optical reporters for enabling sensitive point-of-care diagnostics, particularly with smartphone-based biosensing devices in testing formats such as the lateral flow assay (LFA). Here, the development of persistent phosphors for this application is focused on the solid solution (Sr<sub>1-δsub>Baδ)>2sub>MgSi>2sub>O>7sub>:Eu2+,Dy3+ (δ = 0, 0.125, 0.25, 0.375), which is prepared using a high-temperature solid-state reaction as confirmed by synchrotron X-ray powder diffraction. The substitution of barium for strontium enables control over the Eu2+ 5d-orbital crystal field splitting (CFS) as a tool for tuning the emission wavelength while maintaining luminescence lifetimes >9 min across the composition range. Thermoluminescence measurements of the solid solution provide evidence that trap states contribute to the persistent lifetimes with the trap depths also remaining constant as a function of composition. Time-gated luminescence images of these compounds are captured on a smartphone arranged in a layout to mimic a point-of-care test and demonstrate the viability of using these materials as optical reporters. Moreover, comparing the blue-emitting (Sr<sub>0.625sub>Ba>0.375sub>)>2sub>MgSi>2sub>O>7sub>:Eu2+,Dy3+ and the green-emitting SrAl<sub>2sub>O>4:sub>Eu2+,Dy3+ in a single LFA-type format shows these two compounds can be detected and resolved simultaneously, thereby permitting the development of a multiplexed LFA.

  11. Cyclotron resonance and De Haas-Van Alphen effect in (BEDT-TTF) sub 8 Hg sub 4 Cl sub 1 sub 2 (C sub 6 H sub 5 Cl) sub 2 organic conductor

    CERN Document Server

    Voskobojnikov, I B; Samarin, N A; Cluchanko, N E; Lyubovskaya, R N; Moshchalkov, V V

    2002-01-01

    Within 0.33-1.44 K temperature range at B <= 50 T magnetic field values one measured the De Haas-Van Alphen effect for (BEDT-TTF) sub 8 Hg sub 4 Cl sub 1 sub 2 (C sub 6 H sub 5 Cl) sub 2 organic quasi-two-dimensional conductor. Analysis of quantum oscillations with regard to data on cyclotron resonance derived for 40-120 GHz frequency interval enabled to determine that a complex spectrum of quantum oscillations was formed by alpha approx 256 T and beta approx 670-610 T fundamental frequencies as well as, by combination and multiple frequencies. It is shown that nature of temperature rearrangement of oscillation spectrum may be interpreted in terms of model taking account of occurrence of magnetic phase transition at T sub c approx 0.9 K and proximity of a fundamental frequency with m* = 1.48m sub 0 efficient mass to the spin dumping condition

  12. Cs[FeSe{sub 2}], Cs{sub 3}[FeSe{sub 2}]{sub 2}, and Cs{sub 7}[Fe{sub 4}Se{sub 8}]. Missing links of known chalcogenido ferrate series

    Energy Technology Data Exchange (ETDEWEB)

    Stueble, Pirmin; Roehr, Caroline [Institut fuer Anorganische und Analytische Chemie, Universitaet Freiburg (Germany)

    2017-11-17

    The three cesium selenido ferrate title compounds with an Se:Fe ratio of 2:1 were synthesized from stoichiometric samples reacting elemental Cs either (A) with Fe and Se in a double-crucible setup (Cs[FeSe{sub 2}], Cs{sub 3}[FeSe{sub 2}]{sub 2}) or (B) with previously prepared FeSe{sub 2} (Cs{sub 3}[FeSe{sub 2}]{sub 2}, Cs{sub 7}[Fe{sub 4}S{sub 8}]) (T{sub max} = 800-1000 C). The pure Fe{sup III} ferrate Cs[FeSe{sub 2}] crystallizes in the Tl[FeSe{sub 2}] type [monoclinic, space group C2/m, a = 1392.95(10), b = 564.43(3), c = 737.44(6) pm, β = 119.163(5) , Z = 4, R{sub 1} = 0.0550]. It is thus not isotypic to all other alkali ferrates(III) A[FeS{sub 2}] and A[FeSe{sub 2}] containing chains of edge-sharing tetrahedra, but crystallizes in a t2 subgroup of the Immm structure of Cs[FeS{sub 2}]. The mixed-valent chain compound Cs{sub 3}[FeSe{sub 2}]{sub 2} is isotypic to its sulfido analogue [orthorhombic, space group Pnma, a = 777.88(6), b = 1151.02(6), c = 1341.61(7) pm, Z = 4, R{sub 1} = 0.0470]. In contrast to the isopunctal Na{sub 3}[FeSe{sub 2}]{sub 2} type K/Rb compounds the chains are only slightly corrugated. The monoclinic, likewise mixed-valent Fe{sup II/III} selenido ferrate Cs{sub 7}[Fe{sub 4}Se{sub 8}] [monoclinic, space group C2/c, a = 1953.79(10), b = 879.71(5), c = 1717.03(10) pm, β = 117.890(2) , Z = 4, R{sub 1} = 0.0816] is isostructural both to the cesium sulfido and tellurido compound. The structure contains oligomeric moieties of four edge sharing [FeSe{sub 4}] tetrahedra forming slightly distorted tetrahedral clusters [Fe{sub 4}Se{sub 8}]{sup 7-}, which are surrounded by a cube of 26 Cs cations. Based on a structure map, the crystal chemistry of the three title compounds is discussed together with all chain/cluster ferrates of the general series A{sub 1+x}[Fe{sup III}{sub 1-x}Fe{sup II}{sub x}Q{sub 2}] (x = 0-1; A = Na, K, Rb, Cs; Q = S, Se, Te). (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Ab-initio electronic structure calculations and properties of [Si{sub x}Sn{sub 1−x}]{sub 3}N{sub 4} ternary nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Pavloudis, Th. [Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Zervos, M. [Nanostructured Materials and Devices Laboratory, Department of Mechanical and Manufacturing Engineering, PO Box 20537, Nicosia 1678 (Cyprus); Komninou, Ph. [Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Kioseoglou, J., E-mail: sifisl@auth.gr [Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece)

    2016-08-31

    We carry out ab initio electronic structure calculations of (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4} using density functional theory with projector augmented-wave potentials under the generalized gradient approximation. We find that the energetically favorable structure of Sn{sub 3}N{sub 4} is the face-centered cubic spinel structure, followed by the hexagonal structure which has energy band gaps of 1.85 eV and 1.44 eV respectively. The (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4} ternary compound can exhibit both cubic and hexagonal crystal structures over the full range of x. However, the cubic structure is found to be energetically favorable for x < 0.3 above which the hexagonal structure of (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4} dominates. The energy band gap can be tuned continuously from 1.44 eV up to 5.8 eV in the case of the hexagonal crystal structure of (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4} and from 1.85 eV to 4.82 eV in the case of cubic (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4}. Nevertheless the energy gap of (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4} is direct only for x < 0.3 when it is cubic and for x < 0.5 when hexagonal. - Highlights: • (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4} exhibits both cubic and hexagonal crystal structures. • The cubic structure is favorable for x < 0.3 and the hexagonal structure for x > 0.3. • The bandgap of hexagonal (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4} may be tuned from 1.44 eV up to 5.8 eV. • The bandgap may be tuned from 1.85 eV to 4.82 eV for the cubic (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4}. • Bandgaps are direct for x < 0.3 (cubic) and for x < 0.5 3 (hexagonal (Si{sub x}Sn{sub 1−x}){sub 3}N{sub 4}).

  14. Variation of k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} for the small-field dosimetric parameters percentage depth dose, tissue-maximum ratio, and off-axis ratio

    Energy Technology Data Exchange (ETDEWEB)

    Francescon, Paolo, E-mail: paolo.francescon@ulssvicenza.it; Satariano, Ninfa [Department of Radiation Oncology, Ospedale Di Vicenza, Viale Rodolfi, Vicenza 36100 (Italy); Beddar, Sam [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77005 (United States); Das, Indra J. [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana 46202 (United States)

    2014-10-15

    Purpose: Evaluate the ability of different dosimeters to correctly measure the dosimetric parameters percentage depth dose (PDD), tissue-maximum ratio (TMR), and off-axis ratio (OAR) in water for small fields. Methods: Monte Carlo (MC) simulations were used to estimate the variation of k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} for several types of microdetectors as a function of depth and distance from the central axis for PDD, TMR, and OAR measurements. The variation of k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} enables one to evaluate the ability of a detector to reproduce the PDD, TMR, and OAR in water and consequently determine whether it is necessary to apply correction factors. The correctness of the simulations was verified by assessing the ratios between the PDDs and OARs of 5- and 25-mm circular collimators used with a linear accelerator measured with two different types of dosimeters (the PTW 60012 diode and PTW PinPoint 31014 microchamber) and the PDDs and the OARs measured with the Exradin W1 plastic scintillator detector (PSD) and comparing those ratios with the corresponding ratios predicted by the MC simulations. Results: MC simulations reproduced results with acceptable accuracy compared to the experimental results; therefore, MC simulations can be used to successfully predict the behavior of different dosimeters in small fields. The Exradin W1 PSD was the only dosimeter that reproduced the PDDs, TMRs, and OARs in water with high accuracy. With the exception of the EDGE diode, the stereotactic diodes reproduced the PDDs and the TMRs in water with a systematic error of less than 2% at depths of up to 25 cm; however, they produced OAR values that were significantly different from those in water, especially in the tail region (lower than 20% in some cases). The microchambers could be used for PDD

  15. Operando and In situ X-ray Spectroscopies of Degradation in La <sub>0.6sub> Sr <sub>0.4sub> Co <sub>0.2sub> Fe <sub>0.8sub> O <sub>3-δsub> Thin Film Cathodes in Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Samson Y.; Ding, Dong; Liu, Mingfei; Liu, Meilin; Alamgir, Faisal M.

    2014-09-09

    Information from ex situ characterization can fall short in describing complex materials systems simultaneously exposed to multiple external stimuli. Operando X-ray absorption spectroscopy (XAS) was used to probe the local atomistic and electronic structure of specific elements in a La<sub>0.6sub>Sr>0.4sub>Co>0.2sub>Fe>0.8sub>O>3-δsub> (LSCF) thin film cathode exposed to air contaminated with H<sub>2sub>O and CO<sub>2sub> under operating conditions. While impedance spectroscopy showed that the polarization resistance of the LSCF cathode increased upon exposure to both contaminants at 750°C, XAS near-edge and extended fine structure showed that the degree of oxidation for Fe and Co decreases with increasing temperature. Synchrotron-based X-ray photoelectron spectroscopy tracked the formation and removal of a carbonate species, a Co phase, and different oxygen moieties as functions of temperature and gas. The combined information provides insight into the fundamental mechanism by which H<sub>2sub>O and CO<sub>2sub> cause degradation in the cathode of solid oxide fuel cells.

  16. Stabilization of MgCr<sub>2sub>O>4sub> spinel in slags of the
    SiO<sub>2sub>-CaO-MgO-Cr>2sub>O>3sub> system

    Directory of Open Access Journals (Sweden)

    Arredondo-Torres, V.

    2006-12-01

    Full Text Available El objetivo de este estudio es analizar el efecto del contenido de MgO y la basicidad de la escoria sobre la estabilidad de las especies mineralógicas del sistema de escoria SiO<sub>2sub>-CaOMgO-
    Cr<sub>2sub>O>3sub>. Se realizaron ensayos al equilibrio a 1600 °C bajo condiciones reductoras (pO2=10-9atm. El contenido de MgO fue de 0 a 12 % masa, el Cr<sub>2sub>O>3sub> de 10% y la basicidad de 1 y 1,5. También se realizó un análisis termodinámico para determinar las fases mineralógicas más estables en la escoria. Los resultados experimentales y calculados muestran que el Cr<sub>2sub>O>3sub> se encuentra principalmente ligado en una fase espinela MgCr<sub>2sub>O>4sub>, incluso a bajos contenidos de MgO. Los resultados obtenidos por microscopia electrónica de barrido (MEB-EDS, muestran la evidencia de tres estructuras cristalinas: (A Octaedros, los cuales
    corresponden a la espinela MgCr<sub>2sub>O>4sub>, (B Cristales alargados que corresponden a la formación de silicatos cálcicos y (C Matriz de silicatos cálcicos con impurezas de Mg y Cr que no cristalizaron por completo.

    El objetivo de este estudio es analizar el efecto del contenido de MgO y la basicidad de la escoria sobre la estabilidad de las especies mineralógicas del sistema de escoria SiO<sub>2sub>-CaOMgO-Cr>2sub>O>3sub>. Se realizaron ensayos al equilibrio a 1600 °C bajo condiciones reductoras (pO<sub>2sub>=10-9atm. El contenido de MgO fue de 0 a 12 % masa, el Cr<sub>2sub>O>3sub> de 10% y la basicidad de 1 y 1,5. También se realizó un análisis termodinámico para determinar las fases mineralógicas más estables en la escoria. Los resultados experimentales y calculados muestran que el Cr<sub>2sub>O>3sub> se encuentra principalmente ligado en una fase espinela MgCr<sub>2sub>O>4sub>, incluso a bajos contenidos de MgO. Los resultados obtenidos por

  17. Hydrothermal synthesis and characterization of Mn{sub 1-} {sub x} Zn {sub x} Fe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Feng Jing [College of Material Science and Chemistry Engineering, Harbin Engineering University, Harbin 150001 (China)]. E-mail: fengjing@hrbeu.edu.cn; Guo Liqin [College of Material Science and Chemistry Engineering, Harbin Engineering University, Harbin 150001 (China); Xu Xiaodong [College of Material Science and Chemistry Engineering, Harbin Engineering University, Harbin 150001 (China); Qi Shuyan [College of Material Science and Chemistry Engineering, Harbin Engineering University, Harbin 150001 (China); Zhang Milin [College of Material Science and Chemistry Engineering, Harbin Engineering University, Harbin 150001 (China)

    2007-05-01

    Mn{sub 1-} {sub x} Zn {sub x} Fe{sub 2}O{sub 4} nanoparticles were prepared by hydrothermal synthesis at 200 deg. C for 12 h and characterized by X-ray powder diffraction (XRD), FESEM and vibrating sample magnetometer (VSM) techniques. The additions of Zn{sup 2+} ions content reduced the nanoparticles size. With the increase of Zn{sup 2+} ions content, the Curie temperature (T {sub c}) increased firstly and then decreased; when x=0.3 the T {sub c} reaches the maximum value (430 K). The results could be explained that the Zn{sup 2+} ions changed spin ordering to increase the T {sub c} in the range of x{<=}0.3, and magnetic properties were decreased because of increase of nonmagnetic Zn{sup 2+} ions in the range of x>0.3.

  18. Thermoelectric properties in Ce{sub 1-x}La{sub x}Fe{sub 4}P{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, H. [Faculty of Integrated Arts and Sciences, University of Tokushima, Minamijosanjima-machi, Tokushima 770 8502 (Japan)]. E-mail: sugawara@ias.tokushima-u.ac.jp; Yuasa, S. [Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa, Hachioji, Tokyo 192 0397 (Japan); Tsuchiya, A. [Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa, Hachioji, Tokyo 192 0397 (Japan); Aoki, Y. [Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa, Hachioji, Tokyo 192 0397 (Japan); Sato, H. [Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa, Hachioji, Tokyo 192 0397 (Japan); Sasakawa, T. [Department of Quantume Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739 8530 (Japan); Takabatake, T. [Department of Quantume Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739 8530 (Japan)

    2006-05-01

    We have measured the electrical resistivity {rho}, thermoelectric power S, and thermal conductivity {kappa} in single-crystalline Ce{sub 1-x}La{sub x}Fe{sub 4}P{sub 12}. La-substitution by 1% destroys the energy gap, suggesting that the coherence among the Ce-ions plays an important role for the semiconducting behavior. Within the investigated concentration range, the maximum power factor S{sup 2}/{rho} is found to be 21{mu}Wcm{sup -1}K{sup -2} at room temperature.

  19. Sub-Saharan Africa Report

    National Research Council Canada - National Science Library

    1986-01-01

    .... This report contains articles from Sub-Saharan Africa, Angola, Ethiopia, Ghana, Mozambique, Namibia, Sierra Leone, Togo, Zambia, and South Africa, the articles deal mainly with Politics, Sociology...

  20. Sub-Saharan Africa Report

    National Research Council Canada - National Science Library

    1987-01-01

    Partial Contents: Sub Saharan Africa, Military Exercise, Radio Commentary, Stock Exchange, Prime Minister, Economic, Domestic Service, Armed Forces, Health, Organizations, Death, International Service, Foreign Policy...

  1. Sub-Saharan Africa Report

    National Research Council Canada - National Science Library

    1985-01-01

    .... This report from Sub-Sahara Africa, Angola, Cameroon, Equatorial Guinea, Ethiopia, Gambia, Kenya, Malawi, Namibia, Mozambique, Niger, Nigeria, Senegal, Sierra Leone, South Africa, Tanzania, Uganda...

  2. Sub-Saharan Africa Report

    National Research Council Canada - National Science Library

    1985-01-01

    .... This report from Sub-Saharan Africa, Benin, Botswana, Burkina, Cameroon, Chad, Comoros, Ethiopia, Ghana, Guinea, Kenya, Liberia, Madagascar, Mauritius, Mozambique, Sierra Leone, Somalia, South Africa...

  3. Sub-Saharan Africa Report

    National Research Council Canada - National Science Library

    1985-01-01

    .... This report on Sub-Saharan Africa, Angola, Botswana, Burkina, Cameroon, Ghana, Ivory Coast, Liberia, Madagascar, Malawi, Mali, Mozambique, Namibia, Senegal, South Africa, and Swaziland, contains...

  4. Niobium thiobromide, Nb{sub 3}SBr{sub 7}, with triangle Nb{sub 3} cluster: Structure and bonding

    Energy Technology Data Exchange (ETDEWEB)

    Khvorykh, G.V.; Shevelkov, A.V.; Dolgikh, V.A.; Popovkin, B.A. [Moscow State Univ., Moscow (Russian Federation)

    1995-12-01

    The reaction of Nb, S, and Br{sub 2} in a sealed quartz ampoule at 550{degrees}C yielded Nb{sub 3}SBr{sub 7}. The structure of Nb{sub 3}SBr{sub 7} determined by the single-crystal X-ray diffraction method (P3m1, a=7.1012(6){angstrom}, c=6.3040(9){angstrom}, V=275.30(9){angstrom}{sup 3}, Z=1, d{sub calc}=5.248(2) g.cm{sup 3}, R=0.0395, R{sub w}=0.0392) consists of one-layer packing of ([Nb{sub 3}SBr{sub 3}]Br{sub 6/2}Br{sub 3/3}){sup 2}{infinity} layers. The molecular orbitals of the model anions [Nb{sub 3}Br{sub 13}]{sup 5-} and [Nb{sub 3}SBr{sub 12}]{sup {minus}5-}, which involve the triangle Nb{sub 3} cluster with the nearest ligand environment in the structures of Nb{sub 3}Br{sub 8} and Nb{sup 3}SBr{sub 7} respectively, were calculated by applying the extended Huckel method. The HOMO in [Nb{sub 3}Br{sub 13}]{sup 5-} has slightly metal-metal bonding character which is consistent with an Nb-Nb bond length increase from 2.88 {angstrom} in a seven-electron Nb{sub 3}Br{sub 8} to 2.896(1) {angstrom} in a six-electron Nb{sub 3}SBr{sub 7}. The bonding schemes are in accordance with magnetic properties of Nb{sub 3}Br{sub 8}, which is a paramagnetic, and Nb{sub 3}SBr{sub 7}, which is diamagnetic.

  5. Influence of temperature and frequency on ionic conductivity of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    El Moudane, M., E-mail: m.elmoudane@gmail.com [Laboratoire de Matériaux, Nanotechnologies et Environnement, Université Mohammed V de Rabat, Faculté des Sciences, Av. Ibn Batouta, B.P. 1014 Rabat (Morocco); El Maniani, M.; Sabbar, A. [Equipe de Physico-chimie des Matériaux et Nanomatériaux: Dépollution, Environnement et Développement Durable, Université Mohammed V de Rabat, Faculté des Sciences, Av. Ibn Batouta, B.P. 1014 Rabat (Morocco); Ghanimi, A.; Tabyaoui, M.; Bellaouchou, A.; Guenbour, A. [Laboratoire de Matériaux, Nanotechnologies et Environnement, Université Mohammed V de Rabat, Faculté des Sciences, Av. Ibn Batouta, B.P. 1014 Rabat (Morocco)

    2015-12-15

    Highlights: • Results of ionic conductivities of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses. • Determination of glass transition temperature using DSC method. • Study of temperature and frequency on ionic conductivity of Li{sub 3}PO{sub 4}–Pb{sub 3}(PO{sub 4}){sub 2}–BiPO{sub 4} phosphate glasses. - Abstract: Lithium–Lead–Bismuth phosphates glasses having, a composition 30Li{sub 3}PO{sub 4}–(70 − x)Pb{sub 3}(PO{sub 4}){sub 2}–xBiPO{sub 4} (45 ≤ x ≤ 60 mol%) were prepared by using the melt quenching method 1000 °C. The thermal stability of theses glasses increases with the substitution of Bi{sub 2}O{sub 3} with PbO. The ionic conductivity of all compositions have been measured over a wide temperature (200–500 °C) and frequency range (1–106 Hz). The ionic conductivity data below and above T{sub g} follows Arrhenius and Vogel–Tamman–Fulcher (VTF) relationship, respectively. The activation energies are estimated and discussed. The dependence in frequency of AC conductivity is found to obey Jonscher’s relation.

  6. Kinetic generation of cis-C[sub 5]H[sub 5](CO)[sub 2]ReH[sub 2] from the reaction of C[sub 5]H[sub 5](CO)[sub 2]Re([mu]-H)Pt(H)(PPh[sub 3])[sub 2] with diphenylacetylene

    Energy Technology Data Exchange (ETDEWEB)

    Casey, C.P.; Tanke, R.S.; Hazin, P.N.; Kemnitz, C.R.; McMahon, R.J. (Univ. of Wisconsin, Madison (United States))

    1992-12-23

    Protonation of K[C[sub 5]H[sub 5](CO)[sub 2]ReH] with CF[sub 3]CO[sub 2]H at [minus]78[degrees]C produced a 65:35 mixture of cis-C[sub 5]H[sub 5](CO)[sub 2]ReH[sub 2] (cis-1) and trans-C[sub 5]H[sub 5](CO)[sub 2]ReH[sub 2] (trans-1). At 24[degrees]C, this mixture equilibrated to a 2:98 cis-1:trans-1 mixture. Reaction of C[sub 5]H[sub 5](CO)[sub 2]Re([mu]-H)Pt(H)(PPh[sub 3])[sub 2] (3-Ph) with diphenylacetylene at [minus]9[degrees]C initially produced an 84:16 cis-1:trans-1 mixture. Photolysis of trans-1 in a methylcyclohexane glass at 10 K gave a 40:60 cis-1:trans-1 photostationary state. cis-C[sub 5]H[sub 5](CO)[sub 2]ReHD (cis-1-HD) has an unusual intermediate magnitude of J[sub HD] = 6.5 Hz, which suggested the possibility that cis-1 might be in equilibrium with C[sub 5]H[sub 5](CO)[sub 2]Re([eta][sup 2]-HD) (cis-1-[eta][sup 2]-HD). Howevr, it was not possible to detect measurable amounts of C[sub 5]H[sub 5](CO)[sub 2]Re([eta][sup 2]-H[sub 2]) (cis-1-[eta][sup 2]-H[sub 2]) by IR spectroscopy. 30 refs., 1 fig., 2 tabs.

  7. Simulation of CO<sub>2sub> Storage

    Energy Technology Data Exchange (ETDEWEB)

    McNabb, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Myers, K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    This report is a compilation of Lawrence Livermore National Laboratory’s (LLNL) accomplishments on CO<sub>2sub> storage simulation and modeling research, performed for the US-­China Clean Energy Research Center (CERC). Within the CERC project management structure, this work is referred to as Subtask 6.4.a Simulation and Modeling. The task falls under CERC’s Advanced Coal Technology Consortium (ACTC) Research Theme 6—CO<sub>2sub> Sequestration Capacity and Near-­Term Opportunities. The goals of the task were to develop new CO<sub>2sub> sequestration simulation approaches and tools, then apply them to CO<sub>2sub> storage projects in the U.S. and China. Work on this task paused when funding was redirected to CERC’s other efforts. Two sections of this report provide valuable snapshot of LLNL’s progress when funding was curtailed: 1) Section 5.2.2 is a 14-­page presentation written January 8, 2013; and 2) Section 5.1.3 is a progress report from the first quarter of Fiscal year 2013.

  8. Defect model of a tetragonal Sm sup 3 sup + center found from EPR measurements in CaF sub 2 and SrF sub 2 crystals

    CERN Document Server

    Zheng Wen Chen; Wu Shao Yi; Tang Sheng

    2003-01-01

    The EPR parameters (g factors g sub p sub a sub r sub a sub l sub l sub e sub l , g sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r sub t sub o and hyperfine structure constants A sub p sub a sub r sub a sub l sub l sub e sub l , A sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r sub t sub o) of a tetragonal (C sub 4 sub v) Sm sup 3 sup + center in CaF sub 2 and SrF sub 2 crystals are calculated by considering the crystal-field J-mixing among the ground sup 6 H sub 5 sub / sub 2 , the first excited sup 6 H sub 7 sub / sub 2 and second excited sup 6 H sub 9 sub / sub 2 state multiplets. In the calculations the free-ion and crystal-field parameters of the tetragonal Sm sup 3 sup + -F sup - center obtained from polarized laser-selective excitation spectroscopy are used. The calculated results suggest that the tetragonal Sm sup 3 sup + -F sup - center is the Sm sup 3 sup + center found by later EPR measurements. The g factors g sub p sub a sub r sub a sub...

  9. In Situ Foaming of Porous (La <sub>0.6sub> Sr <sub>0.4sub> ) <sub>0.98sub> (Co <sub>0.2sub> Fe <sub>0.8sub> ) O <sub>3-δsub> (LSCF) Cathodes for Solid Oxide Fuel Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Gandavarapu, Sodith [US DOE-National Energy Technology Laboratory, 3610 Collins Ferry Road P.O.Box.880 Morgantown West Virginia 26507; Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown West Virginia 26506; Sabolsky, Edward [US DOE-National Energy Technology Laboratory, 3610 Collins Ferry Road P.O.Box.880 Morgantown West Virginia 26507; Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown West Virginia 26506; Sabolsky, Katarzyna [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown West Virginia 26506; Gerdes, Kirk [US DOE-National Energy Technology Laboratory, 3610 Collins Ferry Road P.O.Box.880 Morgantown West Virginia 26507

    2013-07-18

    A binder system containing polyurethane precursors was used to in situ foam (direct foam) a (La{sub 0.6}Sr{sub 0.4}){sub 0.98} (Co{sub 0.2} Fe{sub 0.8}) O{sub 3-{ delta}} (LSCF) composition for solid oxide fuel cell (SOFC) cathode applications. The relation between in situ foaming parameters on the final microstructure and electrochemical properties was characterized by microscopy and electrochemical impedance spectroscopy (EIS), respectively. The optimal porous cathode architecture was formed with a 70 vol% solids loading within a polymer precursor composition with a volume ratio of 8:4:1 (isocyanate: PEG: surfactant) in a terpineol-based ink vehicle. The resultant microstructure displayed a broad pore size distribution with highly elongated pore structure.

  10. Development of mathematical model of H{sub 2}O-HNO{sub 3}-UO{sub 2}(NO{sub 3}){sub 2}-TBP-Diluent System

    Energy Technology Data Exchange (ETDEWEB)

    Ochkin, A.; Gladilov, D.; Nekhaevskiy, S.; Merkushkin, A. [D. Mendeleev University of Chemical Technology of Russia, 9 Miusskay Sqr., Moscow, 125047 (Russian Federation)

    2016-07-01

    The nuclear fuel reprocessing is based on the PUREX process. Usually 30% TBP in hydrocarbon diluents is applied, then the composition of the organic phase can be expressed as H{sub 2}O-HNO{sub 3}-UO{sub 2}(NO{sub 3}){sub 2}-Pu(NO{sub 3}){sub 4}-TBP-diluent. The mathematical model of H{sub 2}O-HNO{sub 3}-UO{sub 2}(NO{sub 3}){sub 2}-TBP-dodecane system has been elaborated. Mole fractions and volume ones and rational activity coefficients have been used in order to create the system of equations on the base of mass action law. The method for calculating activity coefficients was provided. The formation constants of uranyl nitrate di-solvate and mono-solvate and di-solvate of acid have been determined. Interaction between uranyl nitrate di-solvate and dodecane and between TBP and dodecane was taken into account. Activity coefficients of nitric acid and uranyl nitrate in mixed solutions were considered. Errors of adequacy have been determined for the systems containing 30% and 12% TBP concentrations.

  11. Superconductivity in Ba sub 1 sub - sub x K sub x BiO sub 3 : possible scenario of spatially separated Fermi-Bose mixture

    CERN Document Server

    Menushenkov, A P; Kuznetsov, A V; Kagan, M Y

    2001-01-01

    A new scenario for the metal-insulator phase transition and superconductivity in the perovskite-like bismuthates Ba sub 1 sub - sub x K sub x BiO sub 3 (BKBO) is proposed. It is shown that two types of charge carriers, the local pairs (real-space bosons) and the itinerant electrons, exist in the metallic compound BKBO (x >= 0.37). The real-space bosons are responsible for the charge transport in semiconducting BaBiO sub 3 and for superconductivity in the metallic BKBO. The appearance of the Fermi-liquid state as the percolation threshold is overcome (x >= 0.37) explains the observed metal-insulator phase transition. Because bosons and fermions occupy different types of the octahedral BiO sub 6 complexes, they are separated in real space, and therefore, the spatially separated Fermi-Bose mixture of a new type is likely to be realized in the bismuthates. The nature of superconductivity is consistently explained in the framework of this scenario. A new superconducting oxide Ba sub 1 sub - sub x La sub x PbO sub ...

  12. Measurement of |V sub c sub b | using (bar B) sup 0 -> D* sup + (ell) sup - (bar nu) sub e sub l sub l Decays

    CERN Document Server

    Della Ricca, G

    2003-01-01

    A preliminary measurement of |V sub c sub b | and the branching fraction BETA((bar B) sup 0 -> D* sup + (ell) sup - (bar nu) sub e sub l sub l) has been performed based on a sample of about 55,700 (bar B) sup 0 -> D* sup + (ell) sup - (bar nu) sub e sub l sub l decays recorded with the BABAR detector. The decays are identified in the D* sup + -> D sup 0 pi sup + final state, with the D sup 0 reconstructed in three different decay modes. The differential decay rate is measured as a function of the relativistic boost of the D* sup + in the (bar B) sup 0 rest frame. The value of the differential decay rate at ''zero recoil'', namely the point at which the D* sup + is at rest in the (bar B) sup 0 frame, is predicted in Heavy Quark Effective Theory as a kinematic factor times F(1)|V sub c sub b |, where F is the unique form factor governing the decay. We extrapolate the measured differential decay rate to the zero recoil point and obtain F(1)|V sub c sub b | = (34.03 +- 0.24 +- 1.31) x 10 sup - sup 3. Using a theo...

  13. Northern California CO<sub>2sub> Reduction Project

    Energy Technology Data Exchange (ETDEWEB)

    Hymes, Edward [C6 Resources LLC, Houston, TX (United States)

    2010-06-16

    C6 Resources LLC, a wholly owned subsidiary of Shell Oil Company, worked with the US Department of Energy (DOE) under a Cooperative Agreement to develop the Northern California CO<sub>2sub> Reduction Project. The objective of the Project is to demonstrate the viability of using Carbon Capture and Sequestration (CCS) to reduce existing greenhouse gas emissions from industrial sources on a large-scale. The Project will capture more than 700,000 metric tonnes of CO<sub>2sub> per year, which is currently being vented to the atmosphere from the Shell Martinez Refinery in Contra Costa County. The CO<sub>2sub> will be compressed and dehydrated at the refinery and then transported via pipeline to a sequestration site in a rural area in neighboring Solano County. The CO<sub>2sub> will be sequestered into a deep saline formation (more than two miles underground) and will be monitored to assure secure, long-term containment. The pipeline will be designed to carry as much as 1,400,000 metric tonnes of CO<sub>2sub> per year, so additional capacity will be available to accommodate CO<sub>2sub> captured from other industrial sources. The Project is expected to begin operation in 2015. The Project has two distinct phases. The overall objective of Phase 1 was to develop a fully definitive design basis for the Project. The Cooperative Agreement with the DOE provided cost sharing for Phase 1 and the opportunity to apply for additional DOE cost sharing for Phase 2, comprising the design, construction and operation of the Project. Phase 1 has been completed. DOE co-funding is provided by the American Recovery and Reinvestment Act (ARRA) of 2009. As prescribed by ARRA, the Project will stimulate the local economy by creating manufacturing, transportation, construction, operations, and management jobs while addressing the need to reduce greenhouse gas emissions at an accelerated pace. The Project, which will also assist in meeting the CO<sub>2sub> reduction requirements set

  14. Lithium insertion in reduced tungsten oxides. I. Li/sub 9. 0/W/sub 19/O/sub 55/

    Energy Technology Data Exchange (ETDEWEB)

    Rosique-Perez, C.; Gonzalez-Calbet, J.; Vallet-Regi, M.; Alario-Franco, M.A.

    1988-10-01

    Lithium has been inserted chemically at room temperature into the crystallographic shear phase W/sub 19/O/sub 55/. Maximum lithium content was Li/sub 9.0/W/sub 19/O/sub 55/. X-ray diffraction and electron microscopy show that lithium insertion contracts the lattice and causes the doubling of a and b parameters of the W/sub 19/O/sub 55/ unit cell.

  15. Hierarchical geometric frustration in La{sub 3}Cu{sub 2}VO{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Robert, J [Laboratoire Louis Neel, CNRS, 25 avenue des Martyrs, BP 166, 38 042 Grenoble Cedex 9 (France); Canals, B [Laboratoire Louis Neel, CNRS, 25 avenue des Martyrs, BP 166, 38 042 Grenoble Cedex 9 (France); Simonet, V [Laboratoire Louis Neel, CNRS, 25 avenue des Martyrs, BP 166, 38 042 Grenoble Cedex 9 (France); Ballou, R [Laboratoire Louis Neel, CNRS, 25 avenue des Martyrs, BP 166, 38 042 Grenoble Cedex 9 (France); Darie, C [Laboratoire de Cristallographie, CNRS, 25 avenue des Martyrs, BP 166, 38 042 Grenoble Cedex 9 (France); Ouladdiaf, B [Institut Laue-Langevin, BP 154, 38042 Grenoble Cedex (France); Johnson, M [Institut Laue-Langevin, BP 154, 38042 Grenoble Cedex (France)

    2007-04-11

    The crystallographic structure and magnetic properties of La{sub 3}Cu{sub 2}VO{sub 9} were investigated by powder neutron diffraction and magnetization measurements. The compound materializes geometric frustration at two spatial scales, within clusters and between clusters, and at different temperature scales. It is shown by exactly solving the Hamiltonian spectrum that collective spins are formed on each cluster at low temperature before inter-cluster coupling operates.

  16. Direct synthesis of Sr{sub 3}Al{sub 2}(OH){sub 12} from solution for preparation of fine-grained Sr{sub 3}Al{sub 2}O{sub 6} phosphors at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Jianquan, E-mail: jianquanqi@mail.tsinghua.edu.cn [School of Nature Resources & Materials Science, Northeastern University at Qinhuangdao, Qinhuangdao, Hebei Province 066004 (China); Zhang, Xinyi [School of Chemistry, Monash University, Clayton, Victoria 3800 (Australia); Han, Xiumei [School of Nature Resources & Materials Science, Northeastern University at Qinhuangdao, Qinhuangdao, Hebei Province 066004 (China); Li, Yuanyuan; Wu, Xueyang [School of Chemistry, Monash University, Clayton, Victoria 3800 (Australia); Zhong, Ruixia; Guo, Rui [School of Nature Resources & Materials Science, Northeastern University at Qinhuangdao, Qinhuangdao, Hebei Province 066004 (China)

    2016-09-05

    The precursors Sr{sub 3}Al{sub 2}(OH){sub 12} can be directly precipitated from solution near room temperature under the normal pressure. The cubic Sr{sub 3}Al{sub 2}O{sub 6} with fine grain size can be synthesized from Sr{sub 3}Al{sub 2}(OH){sub 12} at the temperature as low as 600 °C. Especially, the rare earth element, such as Eu{sup 3+} etc., as luminescent center, has been simultaneously integrated into the lattices of Sr{sub 3}Al{sub 2}O{sub 6}. The luminescent intensities of the samples annealed at a temperature over 800 °C are strong enough for phosphors, and increase with the annealing temperatures, reach a maximum at 1200 °C and then drop down at 1300 °C. The grain sizes of all the samples annealed below 1200 °C are smaller than 1 μm and suitable for mixing with other phosphors in the applications. The photoluminescent spectra of the Sr{sub 3}Al{sub 2}O{sub 6}:Eu{sup 3+} reveal that the intensities of both emission and excitation peaks increase with the dose of Eu{sup 3+}, and reach maxima at the dose level about 1.2%, then decrease due to concentration quenching. A new excitation band at 230 nm has been observed in heavier doped samples due to the complex point defects produced by association. - Graphical abstract: A novel strategy to prepare a stable hydroxide Sr{sub 3}Al{sub 2}(OH){sub 12} is developed. The strontium aluminates phosphors Eu{sup 3+} doped Sr{sub 3}Al{sub 2}O{sub 6} phosphors with controlled composition can been obtained at a low temperature by using Sr{sub 3}Al{sub 2}(OH){sub 12} as a precursor. - Highlights: • Sr{sub 3}Al{sub 2}(OH){sub 12} can be directly deposited from solution. • Sr{sub 3}Al{sub 2}O{sub 6} can be synthesized from Sr{sub 3}Al{sub 2}(OH){sub 12} at the temperature as low as 600 °C. • Luminescent center integrated into the lattices of Sr{sub 3}Al{sub 2}O{sub 6} at low temperature. • The phosphors with fine grain size and the strong luminescent intensities. • A new excitation band at 230 nm has been

  17. Effects of hydrostatic pressure and temperature on the electron paramagnetic resonance spectrum of off-centre Jahn-Teller [CuF sub 4 F sub 4] sup 6 sup - complexes in SrF sub 2 crystal

    CERN Document Server

    Ulanov, V A; Hoffmann, S K; Zaripov, M M

    2003-01-01

    Pressure and temperature variations of the spin-Hamiltonian parameters and electron paramagnetic resonance (EPR) linewidths of non-central Jahn-Teller [CuF sub 4 F sub 4] sup 6 sup - complexes in SrF sub 2 crystal were studied by continuous-wave EPR. It was found that the static spin-Hamiltonian parameters, found at T = 85 K and at normal pressure (g sub | sub | = 2.491, g sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r = 2.083, a sub p sub a sub r sub a sub l sub l sub e sub l = 360, a sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r = 26, A sub x sub ' sub ' = 96, A sub y sub ' sub ' = 99, A sub z sub ' sub ' = 403 and beta sub e sub x sub p = 17 diameter), are slightly changed with hydrostatic pressure and, at T = 85 K and P = 550 MPa, become equal to g sub | sub | = 2.489, g sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r = 2.083, a sub | sub | 348, a sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l s...

  18. Interfacial Electron Transfer Dynamics Following Laser Flash Photolysis of [Ru(bpy)<sub>2sub>((4,4'-PO<sub>3sub>H>2sub>)>2sub>bpy)]2+ in TiO<sub>2sub> Nanoparticle Films in Aqueous Environments

    Energy Technology Data Exchange (ETDEWEB)

    Brennaman, M. Kyle; Patrocinio, Antonio Otávio T.; Song, Wenjing; Jurss, Jonah W.; Concepcion, Javier J.; Hoertz, Paul G.; Traub, Matthew C.; Murakami Iha, Neyde Y.; Meyer, Thomas J.

    2011-02-16

    Nanosecond laser flash photolysis has been used to investigate injection and back electron transfer from the complex [(Ru(bpy)2(4,4'-(PO<sub>3sub>H>2sub>)>2sub>bpy)]2+ surface-bound to TiO<sub>2sub> (TiO<sub>2sub>-RuII). The measurements were conducted under conditions appropriate for water oxidation catalysis by known single-site water oxidation catalysts. Systematic variations in average lifetimes for back electron transfer, <τbet>, were observed with changes in pH, surface coverage, incident excitation intensity, and applied bias. The results were qualitatively consistent with a model involving rate-limiting thermal activation of injected electrons from trap sites to the conduction band or shallow trap sites followed by site-to-site hopping and interfacial electron transfer, TiO<sub>2sub>(e-)-Ru3+→TiO<sub>2sub>-Ru2+. The appearance of pH-dependent decreases in the efficiency of formation of TiO<sub>2sub>-Ru3+ and in incident-photon-to-current efficiencies with the added reductive scavenger hydroquinone point to pH-dependent back electron transfer processes on both the sub-nanosecond and millisecond–microsecond time scales, which could be significant in limiting long-term storage of multiple redox equivalents.

  19. Varistor and humidity-sensitive properties of SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} ceramics with V{sub 2}O{sub 5} addition

    Energy Technology Data Exchange (ETDEWEB)

    Gaponov, A.V. [Dniepropetrovsk National University, Dniepropetrovsk 49050 (Ukraine); Glot, A.B. [Universidad Tehnologica de la Mixteca, Huajuapan de Leon, Oaxaca 69000 (Mexico)], E-mail: alexglot@mixteco.utm.mx; Ivon, A.I. [Dniepropetrovsk National University, Dniepropetrovsk 49050 (Ukraine); Chack, A.M. [Solid State Institute, Technion, Haifa 32000 (Israel); Jimenez-Santana, G. [Universidad Tehnologica de la Mixteca, Huajuapan de Leon, Oaxaca 69000 (Mexico)

    2007-12-20

    It is shown that tin dioxide based SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} ceramic material exhibits not only varistor properties discussed in the literature but also humidity-sensitive properties. At low electric fields conductivity of SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} ceramics is increased with relative humidity of air, however, highly nonlinear current-voltage characteristic is observed even at relative humidity 93%. Conduction mechanism in this material is grain-boundary controlled and decrease of the barrier height on voltage and on relative humidity is responsible, respectively, for varistor and sensor effects. Slow decrease of the low-field conductivity with time during several months after the sintering or high-temperature heat treatment is observed. Such ageing effect is accompanied by the decrease of the lowest value of the current density at highly nonlinear part of current-voltage characteristic. Addition of V{sub 2}O{sub 5} to SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} causes strong decrease of the nonlinearity coefficient, increase of the low-field conductivity, decrease of the activation energy of electrical conduction and decrease of the humidity sensitivity. At quite small V{sub 2}O{sub 5} addition (about 1 mol.%) the transition to a percolation along the V{sub 2}O{sub 5} phase is assumed. Secondary conductive V{sub 2}O{sub 5} phase acts as a shunt to the grain boundaries.

  20. f-f Magnetic polaron Wigner glass and anomalous superconductivity in U sub 1 sub - sub x Th sub x Be sub 1 sub 3

    CERN Document Server

    Kasuya, T

    2000-01-01

    Mechanisms of the anomalous properties in the heavy fermion superconductor UBe sub 1 sub 3 and its alloys, in particular for the Th dopings, are studied in detail based on the fundamental electronic states to be consistent with all the crucial experimental results. As the reference systems for the magnetic polaron formation, Ce monopnictides, as well as USb and UTe, are mentioned. From detailed systematic studies of the dilute alloy systems, it is postulated that the 5f states in UBe sub 1 sub 3 split into the well-localized core 5f GAMMA sup 2 sub 7 singlet state and other delocalized 5f states situated around the Fermi energy forming the f-f magnetic polarons through the strong intra-atomic ferromagnetic f-f exchange interaction. The accompanied lattice polarons are also shown to play important roles. In the p-d band states, the f-f exchange interaction and the intersite p-f mixing interactions for the p-f Kondo state are of nearly equal strengths causing a rich variety of delicately balanced states. For th...

  1. Negative ion photoelectron spectra of ISO<sub>3sub>, IS<sub>2sub>O>3sub>, and IS<sub>2sub>O>4sub> intermediates formed in interfacial reactions of ozone and iodide/sulfite aqueous microdroplets

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Zhengbo; Hou, Gao-Lei; Yang, Zheng; Valiev, Marat; Wang, Xue-Bin

    2016-12-07

    Three short-lived, anionic intermediates, ISO<sub>3sub>, IS<sub>2sub>O>3sub>, and IS<sub>2sub>O>4sub>, are detected during reactions between ozone and aqueous iodine/sulfur oxides microdroplets. These species may play an important role in ozone-driven inorganic aerosol formation; however their chemical properties remain largely unknown. This is the issue addressed in this work using negative ion photoelectron spectroscopy (NIPES) and ab-initio modeling. The NIPE spectra reveal that all of the three anionic species are characterized by high adiabatic detachment energies (ADEs) - 4.62 ± 0.10, 4.52 ± 0.10, and 4.60 ± 0.10 eV for ISO<sub>3sub>, IS<sub>2sub>O>3sub>, and IS<sub>2sub>O>4sub>, respectively. Vibrational progressions with frequencies assigned to the S–O symmetric stretching modes are also discernable in the ground state transition features. Density functional theory (DFT) calculations show the presence of several low-lying isomers involving different bonding scenarios. Further analysis based on high level CCSD(T) calculations reveal that the lowest energy structures are characterized by formation of I–S and S–S bonds and can be structurally viewed as SO3 linked with I, IS, and ISO for ISO<sub>3sub>, IS<sub>2sub>O>3sub>, and IS<sub>2sub>O>4sub>, respectively. The calculated ADEs and vertical detachment energies (VDEs) are in excellent agreement with the experimental results, further supporting the identified minimum energy structures. The obtained intrinsic molecular properties of these anionic intermediates and neutral radicals should be useful to help understand their photochemical reactions in the atmosphere.

  2. Comparison between the magnetic specific heat of NdBa{sub 2}Cu{sub 3}O{sub x} and DyBa{sub 2}Cu{sub 3}O{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Allenspach, P. [California Univ., San Diego, La Jolla, CA (United States). Inst. of Pure and Applied Physical Sciences]|[California State Univ., San Diego (United States). Dept. of Physics; Lee, B.W. [California Univ., San Diego, La Jolla, CA (United States). Inst. of Pure and Applied Physical Sciences]|[California State Univ., San Diego (United States). Dept. of Physics; Gajewski, D.A. [California Univ., San Diego, La Jolla, CA (United States). Inst. of Pure and Applied Physical Sciences]|[California State Univ., San Diego (United States). Dept. of Physics; Barbeta, V.B. [California Univ., San Diego, La Jolla, CA (United States). Inst. of Pure and Applied Physical Sciences]|[California State Univ., San Diego (United States). Dept. of Physics; Maple, M.B. [California Univ., San Diego, La Jolla, CA (United States). Inst. of Pure and Applied Physical Sciences]|[California State Univ., San Diego (United States). Dept. of Physics; Nieva, G. [Comision Nacional de Energia Atomica (CNEA), San Carlos de Bariloche (Argentina). Centro Atomico Bariloche (CAB); Yoo, S.I. [Ames Lab., IA (United States); Kramer, M.J. [Ames Lab., IA (United States); McCallum, R.W. [Ames Lab., IA (United States); Ben-Dor, L. [Hebrew Univ., Jerusalem (Israel). Dept. of Inorganic and Analytical Chemistry

    1995-02-01

    Low temperature heat-capacity measurements have been performed to study the magnetic ordering in NdBa{sub 2}Cu{sub 3}O{sub x} and DyBa{sub 2}Cu{sub 3}O{sub x}. In order to investigate the type of ordering, magnetic fields up to 6 T and hydrostatic pressures up to 4.5 kbar were applied. While for NdBa{sub 2}Cu{sub 3}O{sub x} and DyBa{sub 2}Cu{sub 3}O{sub x} both the fully oxidized and the fully oxygen reduced samples display long rang antiferromagnetic ordering, only magnetic short range interaction could be found for samples in an intermediate range of oxygen concentration. For NdBa{sub 2}Cu{sub 3}O{sub x}, where superexchange is believed to be the dominant magnetic interaction, T{sub N} is three times higher in the sample with x=6.26 compared to the one with x=6.98. In contrast, T{sub N} of DyBa{sub 2}Cu{sub 3}O{sub x} is almost oxygen independent as expected for this mainly dipolar interacting system. (orig.)

  3. Wear property of silicon nitride in steel-on-Si{sub 3}N{sub 4} and Si{sub 3}N{sub 4}-on-Si{sub 3}N{sub 4} systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu Weimin [Chinese Academy of Sciences, Lanzhou (China). Lab. of Solid Lubrication; Duda, J.L. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemical Engineering; Klaus, E.E. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemical Engineering

    1996-11-15

    A ball-on-three-disc modification of the four-ball wear tester was utilized to evaluate the wear property of Si{sub 3}N{sub 4} lubricated with mineral oil, containing additives such as oleic acid, stearic acid and zinc dialkyldithiophosphate (ZDP). For comparison, the wear of a steel ball on Si{sub 3}N{sub 4} discs and an Si{sub 3}N{sub 4} ball on Si{sub 3}N{sub 4} discs was investigated for identical test conditions, and the worn surfaces of the discs were analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The study indicates that the steel ball-on-Si{sub 3}N{sub 4} disc system usually gives less wear of the Si{sub 3}N{sub 4} disc compared with the Si{sub 3}N{sub 4} ball-on-Si{sub 3}N{sub 4} disc system. Among the three tested additives, ZDP shows best antiwear property even at a load of 396 N in the Si{sub 3}N{sub 4} ball-on-Si{sub 3}N{sub 4} disc system. XPS results reveal that a protective surface film containing the products of degraded ZDP was formed on the rubbed surfaces. (orig.)

  4. Conducting interfaces between amorphous layers and SrTiO<sub>3sub>(110) and SrTiO<sub>3sub>(111)

    Energy Technology Data Exchange (ETDEWEB)

    Varela, Maria [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. Complutense de Madrid, Madrid (Spain); Scigaj, Mateusz [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Bellaterra (Spain); Univ. Autonoma de Barcelona, Bellaterra (Spain); Gazquez, Jaume [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Bellaterra (Spain); Fontcuberta, Josep [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Bellaterra (Spain); Herranz, Gervasi [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Bellaterra (Spain); Sanchez, Florencio [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Bellaterra (Spain)

    2015-09-27

    Interfaces between (110) and (111)SrTiO<sub>3sub> (STO) single crystalline substrates and amorphous oxide layers, LaAlO<sub>3sub> (a-LAO), Y:ZrO<sub>2sub> (a-YSZ), and SrTiO<sub>3sub> (a-STO) become conducting above a critical thickness t<sub>c>. Here we show that t<sub>c> for a-LAO does not depend on the substrate orientation, i.e. t<sub>c> (a-LAO/(110)STO) ≈ t<sub>c>(a-LAO/(111)STO) interfaces, whereas it strongly depends on the composition of the amorphous oxide: t<sub>c>(a-LAO/(110)STO) < t<sub>c>(a-YSZ/(110)STO) < t<sub>c>(a-STO/(110)STO). It is concluded that the formation of oxygen vacancies in amorphous-type interfaces is mainly determined by the oxygen affinity of the deposited metal ions, rather than orientation-dependent enthalpy vacancy formation and diffusion. Furthermore, scanning transmission microscopy characterization of amorphous and crystalline LAO/STO(110) interfaces shows much higher amount of oxygen vacancies in the former, providing experimental evidence of the distinct mechanism of conduction in these interfaces.

  5. Observation of cyclotron resonance and electron-phonon coupling in surface states of the bulk-insulating topological insulator Cu<sub>0.02sub>Bi>2sub>Se>3sub>

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Liang [Johns Hopkins Univ., Baltimore, MD (United States). The Inst. of Quantum Matter; Tse, Wang-Kong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Morris, C. M. [Johns Hopkins Univ., Baltimore, MD (United States). The Inst. of Quantum Matter; Brahlek, M. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Koirala, N. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Oh, S. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Armitage, N. P. [Johns Hopkins Univ., Baltimore, MD (United States). The Inst. of Quantum Matter

    2015-02-05

    We have utilized magneto-optical time-domain spectroscopy to investigate the low frequency optical response of topological insulator Cu<sub>0.02sub>Bi>2sub>Se>3sub> and Bi<sub>2sub>Se>3sub> films. With both field and frequency depedence, such experiments give sufficient information to measure the mobility and carrier density of multiple conduction channels simultaneously. We observe sharp cyclotron resonances (CRs) in both samples. The small amount of Cu substitution into the Cu<sub>0.02sub>Bi>2sub>Se>3sub> induces a true bulk insulator with only a single conduction channel with total sheet carrier density 4.9 x 1012/cm2 and mobility as large as 4000 cm2/V s. This is consistent with pure topological surface state (TSSs) conduction with a chemical potential 150 meV above the Dirac point. Hence, a true topological insulator with an insulating bulk is realized. The CR broadens at high fields, an e ect that we attribute to an electron-phonon interaction. This assignment is supported by an extended Drude model analysis on the zero field data. In contrast to Cu<sub>0.02sub>Bi>2sub>Se>3sub>, two charge channels were observed in normal Bi<sub>2sub>Se>3sub> films. We demonstrate a method to distinguish between the dominant TSSs and trivial bulk/2DEG states. The dominant channel exhibits a CR with a carrier density of ~2.0 x 1013/cm2 and mobility ~3200 cm2/V s, consistent with TSSs with a chemical potential ~350meV above the Dirac point.

  6. Phase relations, crystal structure, and phase transformation of In{sub 1−x}Nb{sub 1−x}Ti{sub 2x}O{sub 4} (0 ≤ x < 0.45) in In{sub 2}O{sub 3}–Nb{sub 2}O{sub 5}–TiO{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Su, Liumei; Fan, Xing [School of Materials Science and Engineering, Central South University, Changsha, 410083, Hunan (China); Education Ministry Key Laboratory of Non-ferrous Materials Science and Engineering, Central South University, Changsha, 410083, Hunan (China); Cai, Gemei, E-mail: caigemei@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha, 410083, Hunan (China); Education Ministry Key Laboratory of Non-ferrous Materials Science and Engineering, Central South University, Changsha, 410083, Hunan (China); Liu, Huashan [School of Materials Science and Engineering, Central South University, Changsha, 410083, Hunan (China); Education Ministry Key Laboratory of Non-ferrous Materials Science and Engineering, Central South University, Changsha, 410083, Hunan (China); Jin, Zhanpeng, E-mail: jin@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha, 410083, Hunan (China); Education Ministry Key Laboratory of Non-ferrous Materials Science and Engineering, Central South University, Changsha, 410083, Hunan (China)

    2015-12-05

    Phase relations, crystal structures, and phase transformation of In{sub 1−x}Nb{sub 1−x}Ti{sub 2x}O{sub 4} (0 ≤ x < 0.45) in In{sub 2}O{sub 3}–Nb{sub 2}O{sub 5}–TiO{sub 2} ternary system were investigated for the first time. A number of samples with different compositions were prepared by a solid-state reaction method, and phase assembles were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe micro-analysis (EPMA). Five three-phase regions, ten two-phase regions, and six single-phase solid solutions were determined in this system. The solid solution of In{sub 1−x}Nb{sub 1−x}Ti{sub 2x}O{sub 4} (0 ≤ x < 0.45) is composed of both ordered monoclinic wolframite-type structure (0 ≤ x < 0.35) and disordered orthorhombic α-PbO{sub 2} type structure (0.35 < x < 0.45). Driving force for composition-driven phase transformation in In{sub 1−x}Nb{sub 1−x}Ti{sub 2x}O{sub 4} (0 ≤ x < 0.45) stems from the ordering of cations. The ever reported compound InNbTiO{sub 6} with an orthorhombic α-PbO{sub 2} type structure was amended to be a monoclinic wolframite-type structure. Present investigations will be useful for the whole ceramic community working with In{sub 2}O{sub 3}–Nb{sub 2}O{sub 5}–TiO{sub 2} ternary system as well as for the development of functional materials. - Highlights: • Phase relations of In{sub 2}O{sub 3}–Nb{sub 2}O{sub 5}–TiO{sub 2} ternary system were constructed. • Crystal structures of a novel solid solution In{sub 1−x}Nb{sub 1−x}Ti{sub 2x}O{sub 4} were determined. • Crystal structure of InNbTiO{sub 6} was amended to be a wolframite-type structure. • Composition-driven phase transformation of In{sub 1−x}Nb{sub 1−x}Ti{sub 2x}O{sub 4} was investigated.

  7. Microstructures of laser-treated Al{sub 2}O{sub 3}-ZrO{sub 2}-CeO{sub 2} composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zanhwey [Institute of Materials Science and Engineering, National Sun Yat-Sen University, Kaohsiung (Taiwan, Province of China); Ho Newjin [Institute of Materials Science and Engineering, National Sun Yat-Sen University, Kaohsiung (Taiwan, Province of China); Shen Pouyan [Institute of Materials Science and Engineering, National Sun Yat-Sen University, Kaohsiung (Taiwan, Province of China)

    1995-06-15

    This work uses room temperature X-ray diffraction and electron microscopy to investigate the effect of CO{sub 2} laser treatments (800-2000W, 10-15s) on phase transformations and microstructural modification of sintered (1600 C, 4h) disks A{sub x}Z{sub y}C{sub z}(where A, Z and C denote Al{sub 2}O{sub 3}, ZrO{sub 2} and CeO{sub 2} respectively, and the subscripts represent molar ratios). Laser treatments under these conditions caused melting and more or less sublimation of all the samples; subsequent solidification and condension (predominant for CeO{sub 2}-rich composition) resulted in different microstructures between the samples. Dendritic and cellular domain structures due both to eutectic growth of {alpha}-Al{sub 2}O{sub 3} and ZrO{sub 2}-CeO{sub 2} solid solution were found in specimens A{sub 30}Z{sub 63}C{sub 7} and A{sub 70}Z{sub 27}C{sub 3} respectively. In the CeO{sub 2}-rich specimen A{sub 40}Z{sub 12}C{sub 48} a drastic effect of condensation caused dendritic clusters of CeO{sub 2} cubes (fluorite structure with minor amount of ZrO{sub 2} and Al{sub 2}O{sub 3} in solid solution) which overlaid on an Al{sub 2}O{sub 3}-rich matrix, predominantly CeAlO{sub 3}. Condensation through a rapidly solidifying liquid caused incorporation of Al{sub 2}O{sub 3} in the fluorite structure and hence deviation from the octahedral shape predicted by the periodic bond chain model. Solute (Al{sub 2}O{sub 3}) trapping also suppressed the martensitic transformation of tetragonal (t-) to monoclinic (m-) ZrO{sub 2} as manifested by the dendritic t-ZrO{sub 2} cooled from the Al{sub 2}O{sub 3}-ZrO{sub 2} eutectic. Laser treatment increased the Ce{sup 2+}/Ce{sup 4+} ratio and hence darkened the samples. (orig.)

  8. Li{sub 5}Cr{sub 9}Ti{sub 4}O{sub 24}: A new anode material for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chunfu, E-mail: linchunfu@hainu.edu.cn [Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228, Hainan (China); Deng, Shengjue; Shen, Hong; Wang, Guizhen; Li, Yanfang; Yu, Lei; Lin, Shiwei; Li, Jianbao [Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228, Hainan (China); Lu, Li, E-mail: luli@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2015-11-25

    Li{sub 4}Ti{sub 5}O{sub 12} suffers from its small theoretical capacity and low conductivity, limiting its practical applications in lithium-ion batteries. Although its conductivity has been improved, its theoretical capacity has not been increased so far. Here, for the first time, the capacity of Li{sub 4}Ti{sub 5}O{sub 12} is increased by combining Ti{sup 3+}/Ti{sup 4+} and Cr{sup 2+}/Cr{sup 3+} redox couples. Spinel Li{sub 5}Cr{sub 9}Ti{sub 4}O{sub 24} with a larger theoretical capacity of 323 mAh g{sup −1} is designed and fabricated through a facile solid-state reaction method. The as-fabricated Li{sub 5}Cr{sub 9}Ti{sub 4}O{sub 24} delivers a large initial discharge capacity of 311 mAh g{sup −1} between 3 and 0.001 V (vs. Li/Li{sup +}) at a current density of 62.5 mA g{sup −1}, which is larger than that of Li{sub 4}Ti{sub 5}O{sub 12}. Furthermore, it exhibits good (electronic and ionic) conductivity and a high rate performance. - Highlights: • Capacity of Li{sub 4}Ti{sub 5}O{sub 12} is increased by combining Ti{sup 3+}/Ti{sup 4+} and Cr{sup 2+}/Cr{sup 3+} couples. • Spinel Li{sub 5}Cr{sub 9}Ti{sub 4}O{sub 24} with a larger theoretical capacity of 323 mAh g{sup −1} is prepared. • Discharge and charge capacities of Li{sub 5}Cr{sub 9}Ti{sub 4}O{sub 24} are larger than those of Li{sub 4}Ti{sub 5}O{sub 12}. • Li{sub 5}Cr{sub 9}Ti{sub 4}O{sub 24} shows a large electronic conductivity and Li{sup +} diffusion coefficient. • Li{sub 5}Cr{sub 9}Ti{sub 4}O{sub 24} further exhibits an ultra-high rate performance and good cyclability.

  9. Kondo Physics and Unconventional Superconductivity in the U Intermetallic U<sub>2sub>PtC>2sub> Revealed by NMR

    Energy Technology Data Exchange (ETDEWEB)

    Mounce, Andrew M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Thompson, Joe David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-17

    The set of slides begins by discussing the topic NMR of heavy fermion superconductors under the topics heavy fermion materials, superconductivity, and nuclear magnetic resonance. The history of these phenomena is sketched, with particular mention made of CeCu<sub>2sub>Si>2sub>, UPt<sub>3sub>, and UBe<sub>13sub>. Unconventional superconductivity, which is non-phonon mediated superconductivity, presents a high T<sub>c> (up to ~150 K), and involves a more complicated spin/orbital wave function. The presentation then goes on to give experimental NMR results for U<sub>2sub>PtC>2sub> and Pu-115’s.

  10. Synthesis and photoluminescence property of La doped Pb{sub 5}(VO{sub 4}){sub 3}OH rod bunches

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jing; Zhuo, Fengping; Fu, Ya; Wang, Yue; Yuan, Jinhai, E-mail: materialscqust@126.com; Feng, Jian

    2017-05-10

    The pure Pb{sub 5}(VO{sub 4}){sub 3}OH and La doped Pb{sub 5}(VO{sub 4}){sub 3}OH rod bunches have been synthesized by a simple Composite-Hydroxide-Mediated (CHM) method. The characterization of the doped samples with XRD, EDS and XPS indicated that La{sup 3+} ions were incorporated into the Pb{sub 5}(VO{sub 4}){sub 3}OH lattices. The crystallite size of Pb{sub 5}(VO{sub 4}){sub 3}OH:La{sup 3+} rod bunches was smaller than that of pure Pb{sub 5}(VO{sub 4}){sub 3}OH rod bunches. The possible formation mechanism of rod bunches has been discussed. The photoluminescence property of the Pb{sub 5}(VO{sub 4}){sub 3}OH:La{sup 3+} crystals was investigated at room temperature. The crystals exhibited a strong blue luminescence under UV light (353 nm) excitation at room-temperature. The mechanism of excellent luminescence of Pb{sub 5}(VO{sub 4}){sub 3}OH:La{sup 3+} has been deeply discussed. - Highlights: • Pb{sub 5}(VO{sub 4}){sub 3}OH:La{sup 3+} rod bunches have been synthesized by the CHM method. • The possible formation mechanism of rod bunches has been discussed. • The La{sup 3+} doping in the Pb{sub 5}(VO{sub 4}){sub 3}OH rod bunches can improve the blue luminescence property at room temperature remarkably.

  11. Synthesis and characterization of superconductor Bi{sub 3}O{sub 2}S{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Gaobin [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); School of Science, University of Science and Technology Liaoning, Anshan 114051 (China); Li, Da; Li, Shaojie [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Jian [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); School of Science, University of Science and Technology Liaoning, Anshan 114051 (China); Liu, Wei; Zhang, Zhidong [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-03-15

    Highlights: • Layered superconductor Bi{sub 3}O{sub 2}S{sub 3} have been successfully prepared with Bi{sub 2}O{sub 2}S precursor. • The zero resistivity transition temperature of bulk Bi{sub 3}O{sub 2}S{sub 3} is observed at 4.62 K. • The susceptibility at 2 K is 0.031 emu Oe{sup −1} g{sup −1}, indicating a perfect diamagnetism. - Abstract: Bulk and nanoscale powder layered superconductor Bi{sub 3}O{sub 2}S{sub 3} have been successfully prepared via conventional solid-state reaction route. The diffraction peaks observed for Bi{sub 3}O{sub 2}S{sub 3}, except for the small impurity peaks belong to Bi{sub 28}O{sub 32}(SO{sub 4}){sub 10}, can be indexed to the orthorhombic (I4/mmm tetragonal) phase for Bi{sub 3}O{sub 2}S{sub 3} with cell constants a = 3.961 Å, c = 41.316 Å. The pill comprised of nanoscale Bi{sub 3}O{sub 2}S{sub 3} behaves like insulator. However the zero resistivity of bulk Bi{sub 3}O{sub 2}S{sub 3} is observed at 4.62 K. The superconductivity is also proved by the Meissner effect from the zero-field cooled and field cooled dc magnetization measurements, and the diamagnetic susceptibility which reflects shielding volume fraction of superconductor at 2 K is about −0.031 emu Oe{sup −1} g{sup −1}, indicating a perfect diamagnetism.

  12. Nanoscale phase separation in La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 films: evidence for texture-driven optical anisotropy

    CERN Document Server

    Moskvin, A S; Sukhorukov, Y P; Mostovshchikova, E V; Loshkareva, N N; Kaul, A R; Gorbenko, O Y

    2003-01-01

    The infrared optical absorption (0.1 eV < h-bar omega < 1.5 eV) in La sub 0 sub . sub 7 Ca sub 0 sub . sub 3 MnO sub 3 films on LaAlO sub 3 substrates exhibits a drastic temperature evolution of the spectral weight, evidencing an insulator-to-metal transition. Single-crystal films were found to reveal strong linear dichroism with anomalous spectral oscillations and fairly weak temperature dependence. Starting from the concept of phase separation, we develop an effective medium model to account for these effects. The optical anisotropy of the films is attributed to the texturization of the ellipsoidal inclusions of the quasimetal phase caused by a mismatch of the film and substrate and the twin texture of the latter.

  13. Improved photoelectrochemical performance of Z-scheme g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} heterostructure and degradation property

    Energy Technology Data Exchange (ETDEWEB)

    Li, Junqi, E-mail: sfmlab@163.com; Yuan, Huan; Zhu, Zhenfeng

    2016-11-01

    Highlights: • A novel Z-scheme g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} composite was synthesized. • The Z-scheme system we made can remain the strong reducibility and oxidizability of the photocatalysts. • The solar light was made the utmost use both the ultraviolet and visible region light through the g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} composite. - Abstract: In g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}, the p–n junction between p-type Bi{sub 2}O{sub 3} and n-type BiPO{sub 4} was encapsulated by g-C{sub 3}N{sub 4} and a direct Z-scheme was built between g-C{sub 3}N{sub 4} and Bi{sub 2}O{sub 3}. The optical, morphological and photoelectrochemical (PEC) properties of BiPO{sub 4}, g-C{sub 3}N{sub 4}/BiPO{sub 4}, Bi{sub 2}O{sub 3}/BiPO{sub 4} and g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} hierarchical Z-scheme system were studied. More than 90% photodegradation of methyl orange (MO) with the exposure of simulated solar light was achieved within 160 min with the g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}, which displayed remarkably promoted photocatalytic activities than other samples. The electrochemical impedance spectra and photocurrent results also proved that efficient charge separation and better electron transport properties were achieved by g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}. In general, the addition of g-C{sub 3}N{sub 4} can guide the residual electrons on p-type Bi{sub 2}O{sub 3} to recombine with photoholes of g-C{sub 3}N{sub 4} and make sure the left carries exhibit stronger oxidation and reduction ability to boost the production of active groups.

  14. Fabrication and evaluation of In sub 0 sub . sub 5 sub 2 Al sub 0 sub . sub 4 sub 8 As/In sub 0 sub . sub 5 sub 3 Ga sub 0 sub . sub 4 sub 7 As/InP quantum cascade lasers

    CERN Document Server

    Farmer, C D

    2000-01-01

    far-field measurements on the mesa-etched QC lasers confirmed the lasing of higher order modes and more importantly, dramatic changes in the far-field distributions with current. Measurement of the threshold current density gave the waveguide losses approx 30 cm sup - sup 1 which was subsequently traced to an excessive doping level in the substrate. Novel design and fabrication of QC lasers was demonstrated with the planar selective wet oxidation (PSWOX) QC laser. Despite the high waveguide losses arising from the substrate, the PSWOX QCLs still performed very well. Optically they were far superior to our mesa-etched QC lasers, possessing an output beam with a very low divergence and whose far-field profile was stable with increasing drive current. The lasers' ability to dissipate heat also appeared to be enhanced over its counterparts, as demonstrated by its high characteristic temperature T sub 0 (approx 142 K). However, this particular structure was let down by the very poor electrical confinement which le...

  15. Exploring Charge Transport in Guest Molecule Infiltrated Cu<sub>3sub>(BTC)>2sub> Metal Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, Francois Leonard [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Stavila, Vitalie [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Allendorf, Mark D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2014-09-01

    The goal of this Exploratory Express project was to expand the understanding of the physical properties of our recently discovered class of materials consisting of metal-organic frameworks with electroactive ‘guest’ molecules that together form an electrically conducting charge-transfer complex (molecule@MOF). Thin films of Cu<sub>3sub>(BTC)>2sub> were grown on fused silica using solution step-by-step growth and were infiltrated with the molecule tetracyanoquinodimethane (TCNQ). The infiltrated MOF films were extensively characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy, electrical conductivity, and thermoelectric properties. Thermopower measurements on TCNQ@Cu<sub>3sub>(BTC)>2sub> revealed a positive Seebeck coefficient of ~400 μV/k, indicating that holes are the primary carriers in this material. The high value of the Seebeck coefficient and the expected low thermal conductivity suggest that molecule@MOF materials may be attractive for thermoelectric power conversion applications requiring low cost, solution-processable, and non-toxic active materials.

  16. Thermal transport properties of MoS <sub>2sub> and MoSe <sub>2sub> monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Kandemir, Ali; Yapicioglu, Haluk; Kinaci, Alper; Çağın, Tahir; Sevik, Cem

    2016-01-11

    Isolation of single to few layer transition metal dichalgogenides open alternate venues in application of 2 dimensional materials to nanoelectronics. Either for general overheating issues or specific application in thermoelectric devices, the characterization of the thermal transport in these new low dimensional materials is needed for their efficient implementation. In this study, lattice thermal conductivities of single layer MoS<sub>2sub> and MoSe<sub>2sub> are evaluated using classical molecular dynamics method. The interactions between atoms are defined by Stillinger-Weber type empirical potentials that are developed to represent structural, mechanical, and vibrational properties of the given materials. In parameterization of the potentials, a stochastic optimization algorithm, namely particle swarm optimization is utilized. The final parameter sets produce quite consistent results with DFT in terms of lattice parameters, bond distances, elastic constants and vibrational properties of both single layer MoS<sub>2sub> and MoSe<sub>2sub>. The predicted thermal properties of both materials are in very good agreement with earlier first principles calculations. The discrepancies between calculations and experimental measurements are most likely to be caused by pristine nature of the structures in our simulations.

  17. SUB-SLAB PROBE INSTALLATION

    Science.gov (United States)

    Sub-slab sampling has become an integral part of vapor intrusion investigations. It is now recommended in guidance documents developed by EPA and most states. A method for sub-slab probe installation was devised in 2002, presented at conferences through 2005, and finally docume...

  18. Transport mean free path in K{sub 5}Bi{sub 1-x}Nd{sub x}(MoO{sub 4}){sub 4} laser crystal powders

    Energy Technology Data Exchange (ETDEWEB)

    Illarramendi, M A [Departamento de FIsica Aplicada I, Escuela Tecnica Superior de IngenierIa, Universidad del PaIs Vasco, Alda. Urquijo s/n, 48013 Bilbao (Spain); Aramburu, I [Departamento de FIsica Aplicada I, Escuela Tecnica Superior de IngenierIa, Universidad del PaIs Vasco, Alda. Urquijo s/n, 48013 Bilbao (Spain); Fernandez, J [Departamento de FIsica Aplicada I, Escuela Tecnica Superior de IngenierIa, Universidad del PaIs Vasco, Alda. Urquijo s/n, 48013 Bilbao (Spain); Balda, R [Departamento de FIsica Aplicada I, Escuela Tecnica Superior de IngenierIa, Universidad del PaIs Vasco, Alda. Urquijo s/n, 48013 Bilbao (Spain); Al-Saleh, M [Departamento de FIsica Aplicada I, Escuela Tecnica Superior de IngenierIa, Universidad del PaIs Vasco, Alda. Urquijo s/n, 48013 Bilbao (Spain)

    2007-01-24

    In this work, we calculate in two different ways the transport mean free paths in K{sub 5}Bi{sub 1-x}Nd{sub x}(MoO{sub 4}){sub 4} (x = 0.05, 0.2, 1) laser crystal powders by using the diffuse spectral reflectance and transmittance of the powders and the absorption coefficient of the crystal materials. The theoretical calculations have been made by assuming a diffusive propagation of light in these materials. Similar results have been obtained from both methods.

  19. Neutron scattering investigations of the properties of the x - T phase diagram of Rb sub 1 sub - sub x (NH sub 4) sub x I mixed crystals

    CERN Document Server

    Smirnov, L S; Savenko, B N

    2002-01-01

    The x - T phase diagram of Rb sub 1 sub - sub x (NH sub 4) sub x I is studied using samples with the ammonium concentration 0.01

  20. Minimization of lattice parameter change in Czochralski grown (Gd sub 1-x Y sub x ) sub 3 Ga sub 5 O sub 12 garnet single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Hideo; Numazawa, Takenori; Sato, Mitsunori; Maeda, Hiroshi (National Research Inst. for Metals, Ibaraki (Japan)); Sakamoto, Masaru (Nippon Mining Co. Ltd., Saitama (Japan))

    1992-05-01

    Single crystals of (Gd{sub 1-x}Y{sub x}){sub 3}Ga{sub 5}O{sub 12} rare-earth garnet solid solutions were grown by using the Czochralski technique and their lattice parameter change along the growth direction was minimized by means of the combination of a solid solution effect and a nonstoichiometry effect for the garnet. The single crystals are promising magnetic refrigerants for magnetic refrigerators to generate a low temperature atmosphere below 1 K. (orig.).

  1. The Coating Effects of Al{sub 2}O{sub 3} on a Li[Li{sub 0.2}Mn{sub 0.54}Co{sub 0.13}Ni{sub 0.13}]O{sub 2} Surface Modified with (NH{sub 4}){sub 2}SO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jiwoo; Oh, Ryegyeong; Hong, Jungeui; Yang, Wongeun; Ryu, Kwangsun [Univ. of Ulsan, Ulsan (Korea, Republic of)

    2014-05-15

    A series of 20 wt % (NH{sub 4}){sub 2}SO{sub 4} and 3 wt % Al{sub 2}O{sub 3} surface treatments were applied to Li[Li{sub 0.2}Mn{sub 0.54}Co{sub 0.13}Ni{sub 0.13}]O{sub 2} substrates. The Li[Li{sub 0.2}Mn{sub 0.54}Co{sub 0.13}Ni{sub 0.13}]O{sub 2} substrates were synthesized using a co-precipitation method. Sample was left pristine and variations of the 20 wt % (NH{sub 4}){sub 2}SO{sub 4} and 3 wt % Al{sub 2}O{sub 3} were applied to samples, and. XRD was used to verify the space group of the samples as R3m. Additional morphology and particle size data were obtained using SEM imagery. The Al{sub 2}O{sub 3} coating layers of sample and were confirmed by TEM images and EDS mapping of the SEM images. 2032-type coin cells were fabricated in a glove box in order to investigate their electrochemical properties. The cells were charged and discharged at room temperature (25 .deg. C) between 2.0V and 4.8V during the first cycle. The cells were then charged and discharged between 2.0V and 4.6V in subsequent cycles. Sample exhibited lower irreversible capacity loss (ICL) in the first charge-discharge cycle as compared to sample. Sample also had a higher discharge capacity of ∼250 mAh/g during the first and second charge-discharge cycles when compared with sample. The rate capability of the Al{sub 2}O{sub 3}-coated sample (b) and (d) was lower when compared with sample and. Sample, coated with Al{sub 2}O{sub 3} after the surface treatment with (NH{sub 4}){sub 2}SO{sub 4}, showed an improvement in cycle performance as well as an enhancement of discharge capacity. The thermal stability of sample was higher than that of the sample as the result of DSC.

  2. Molecular mechanism of pancreatic tumor metastasis inhibition by Gd@C<sub>82sub>(OH)>22sub> and its implication for de novo design of nanomedicine

    Energy Technology Data Exchange (ETDEWEB)

    Kang, S. -g.; Zhou, G.; Yang, P.; Liu, Y.; Sun, B.; Huynh, T.; Meng, H.; Zhao, L.; Xing, G.; Chen, C.; Zhao, Y.; Zhou, R.

    2012-09-18

    Pancreatic adenocarcinoma is the most lethal of the solid tumors and the fourth-leading cause of cancer-related death in North America. Matrix metalloproteinases (MMPs) have long been targeted as a potential anticancer therapy because of their seminal role in angiogenesis and extracellular matrix (ECM) degradation of tumor survival and invasion. However, the inhibition specificity to MMPs and the molecular-level understanding of the inhibition mechanism remain largely unresolved. Here, we found that endohedral metallofullerenol Gd@C<sub>82sub>(OH)>22sub> can successfully inhibit the neoplastic activity with experiments at animal, tissue, and cellular levels. Gd@C<sub>82sub>(OH)>22sub> effectively blocks tumor growth in human pancreatic cancer xenografts in a nude mouse model. Enzyme activity assays also show Gd@C<sub>82sub>(OH)>22sub> not only suppresses the expression of MMPs but also significantly reduces their activities. We then applied large-scale molecular-dynamics simulations to illustrate the molecular mechanism by studying the Gd@C<sub>82sub>(OH)>22sub>–MMP-9 interactions in atomic detail. Our data demonstrated that Gd@C<sub>82sub>(OH)>22sub> inhibits MMP-9 mainly via an exocite interaction, whereas the well-known zinc catalytic site only plays a minimal role. Steered by nonspecific electrostatic, hydrophobic, and specific hydrogen-bonding interactions, Gd@C<sub>82sub>(OH)>22sub> exhibits specific binding modes near the ligand-specificity loop S1', thereby inhibiting MMP-9 activity. Both the suppression of MMP expression and specific binding mode make Gd@C<sub>82sub>(OH)>22sub> a potentially more effective nanomedicine for pancreatic cancer than traditional medicines, which usually target the proteolytic sites directly but fail in selective inhibition. Finally, our findings provide insights for de novo design of nanomedicines for fatal diseases such as pancreatic cancer.

  3. Study on collisional deactivation of O{sub 2}({sup 1}{Delta}{sub g}) by H{sub 2} and D{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Du Shuyan [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Leng Jing, E-mail: ljjx@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Wang Junhui; Yang Heping; Sha Guohe; Zhang Cunhao [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2011-05-26

    Highlights: {yields} The deactivation rate constants of O{sub 2}({sup 1}{Delta}{sub g}) by H{sub 2} and D{sub 2} are measured. {yields} The figures agree well with the quantum mechanical calculation by Kustrev. {yields} The O{sub 2}({sup 1}{Delta}{sub g}) deactivation by H{sub 2}/D{sub 2} is analyzed by Schmidt's E-V energy transfer model. {yields} The main deactivation channels of O{sub 2}({sup 1}{Delta}{sub g}) for H{sub 2} and D{sub 2} are given respectively. - Abstract: The deactivation rate constants of O{sub 2}({sup 1}{Delta}{sub g}) by H{sub 2} and D{sub 2} are respectively measured to be 3.91 {+-} 0.12 x 10{sup -18} cm{sup 3} s{sup -1} and 1.1 {+-} 0.3 x 10{sup -19} cm{sup 3} s{sup -1}, which agree well with the quantum mechanical calculation by Kustrev. Their deactivation mechanisms by H{sub 2} and D{sub 2} are analyzed according to the E-V energy transfer model developed by Schmidt, indicating that the main deactivation channel for H{sub 2} is O{sub 2}({sup 1}{Delta}{sub g},v=0{yields}{sup 3}{Sigma}{sub g}{sup -},v{sup ''}=0) and H{sub 2} ({Delta}v = 2), while that for D{sub 2} is O{sub 2}({sup 1}{Delta}{sub g},v{sup '}=0{yields}{sup 3}{Sigma}{sub g}{sup -},v{sup ''}=1) and D{sub 2} ({Delta}v = 2), which entirely matches the calculation by Kustrev.

  4. Thermoelectric properties of Sn- and Pb-doped Tl{sub 9}BiTe{sub 6} and Tl{sub 9}SbTe{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Quansheng; Chan, Meghan; Kuropatwa, Bryan A.; Kleinke, Holger, E-mail: kleinke@uwaterloo.ca [Department of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2014-11-14

    A variety of substitutions in Tl{sub 9}BiTe{sub 6} and Tl{sub 9}SbTe{sub 6} with Sn and Pb, amounting to 14 different samples, were performed by melting the stoichiometric amounts of elements at 923 K, followed by slow cooling. The pulverized powders were sintered using the hot-pressing technique. All samples were of single phase according to the powder X-ray diffraction patterns. Thermoelectric property measurements were performed to investigate the effects of Sn- and Pb-doping on the electrical conductivity, Seebeck coefficient, and thermal conductivity. Increasing the concentration of the dopants caused increases in electrical and thermal conductivity, while decreasing the Seebeck coefficient. Tl{sub 9}Bi{sub 0.90}Pb{sub 0.10}Te{sub 6} and Tl{sub 9}Bi{sub 0.85}Pb{sub 0.15}Te{sub 6} exhibited the highest power factor. The changes in lattice thermal conductivity were minor and did not follow a clear trend. Competitive ZT values were obtained for Tl{sub 9}Bi{sub 0.95}Sn{sub 0.05}Te{sub 6}, Tl{sub 9}Bi{sub 0.95}Pb{sub 0.05}Te{sub 6}, Tl{sub 9}Sb{sub 0.97}Sn{sub 0.03}Te{sub 6}, and Tl{sub 9}Sb{sub 0.95}Pb{sub 0.05}Te{sub 6}, namely 0.95, 0.94, 0.83, and 0.71 around 500 K, respectively. Higher dopant concentrations led to lower ZT values.

  5. Structural Evolution and Atom Clustering in β-SiAlON: β-Si <sub>6–zsub> Al <sub>z> O <sub>z> N <sub>8–zsub>

    Energy Technology Data Exchange (ETDEWEB)

    Cozzan, Clayton; Griffith, Kent J.; Laurita, Geneva; Hu, Jerry G.; Grey, Clare P.; Seshadri, Ram (UCSB); (Cambridge)

    2017-02-06

    SiAlON ceramics, solid solutions based on the Si<sub>3sub>N>4sub> structure, are important, lightweight structural materials with intrinsically high strength, high hardness, and high thermal and chemical stability. Described by the chemical formula β-Si<sub>6–zsub>Al<sub>zOzN>8–zsub>, from a compositional viewpoint, these materials can be regarded as solid solutions between Si<sub>3sub>N>4sub> and Al<sub>3sub>O>3sub>N. A key aspect of the structural evolution with increasing Al and O (z in the formula) is to understand how these elements are distributed on the β-Si<sub>3sub>N>4sub> framework. The average and local structural evolution of highly phase-pure samples of β-Si<sub>6–zsub>Al<sub>zOzN>8–zsub> with z = 0.050, 0.075, and 0.125 are studied here, using a combination of X-ray diffraction, NMR studies, and density functional theory calculations. Synchrotron X-ray diffraction establishes sample purity and indicates subtle changes in the average structure with increasing Al content in these compounds. Solid-state magic-angle-spinning 27Al NMR experiments, coupled with detailed ab initio calculations of NMR spectra of Al in different AlO<sub>qN>4–qsub> tetrahedra (0 ≤ q ≤ 4), reveal a tendency of Al and O to cluster in these materials. Independently, the calculations suggest an energetic preference for Al–O bond formation, instead of a random distribution, in the β-SiAlON system.

  6. Improved corrosion resistance of Sr substituted YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Bhalla, G.L.; Sharma, S.; Trigunayat, G.C. [Delhi Univ. (India). Dept. of Physics and Astrophysics

    1998-09-16

    The partial substitution of Sr at Ba sites in YBa{sub 2-x}Sr{sub x}Cu{sub 3}O{sub 7-{delta}} (0 < x < 0.6) has been carried out. The samples are treated with deionized water for 16 h. The influence of water on the corrosion resistance of YBa{sub 2-x}Sr{sub x}Cu{sub 3}O{sub 7-{delta}} is examined by the changes in T{sub c}, lattice parameters, orthorhombicity and oxygen contents. The results indicate that the corrosion resistance of YBa{sub 1.8}Sr{sub 0.2}Cu{sub 3}O{sub 6.882} against treatment with water is enhanced. (orig.) 24 refs.

  7. PdAgAu alloy with high resistance to corrosion by H<sub>2sub>S

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Fernando [Inst. de Investigaciones en Catalisis y Petroquimica, Santa Fe (Argentina); Miller, James B. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Chemical Engineering; National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Gellman, Andrew J. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Chemical Engineering; National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Tarditi, Ana M. [Inst. de Investigaciones en Catalisis y Petroquimica, Santa Fe (Argentina); Fleutot, Benoit [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Chemical Engineering; Kondratyuk, Petro [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Chemical Engineering; National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Cornaglia, Laura M. [Inst. de Investigaciones en Catalisis y Petroquimica, Santa Fe (Argentina)

    2012-12-01

    PdAgAu alloy films were prepared on porous stainless steel supports by sequential electroless deposition. Two specific compositions, Pd<sub>83sub>Ag>2sub>Au>15sub> and Pd<sub>74sub>Ag>14sub>Au>12sub>, were studied for their sulfur tolerance. The alloys and a reference Pd foil were exposed to 1000 H<sub>2sub>S /H<sub>2sub> at 623 K for periods of 3 and 30 hours. The microstructure, morphology and bulk composition of both nonexposed and H<sub>2sub>S-exposed samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). XRD and SEM analysis revealed time-dependent growth of a bulk Pd{sub 4}S phase on the Pd foil during H<sub>2sub>S exposure. In contrast, the PdAgAu ternary alloys displayed the same FCC structure before and after H<sub>2sub>S exposure. In agreement with the XRD and SEM results, sulfur was not detected in the bulk of either ternary alloy samples by EDS, even after 30 hours of H<sub>2sub>S exposure. X-ray photoelectron spectroscopy (XPS) depth profiles were acquired for both PdAgAu alloys after 3 and 30 hours of exposure to characterize sulfur contamination near their surfaces. Very low S 2p and S 2s XPS signals were observed at the top-surfaces of the PdAgAu alloys, and those signals disappeared before the etch depth reached ~ 10 nm, even for samples exposed to H<sub>2sub>S for 30 hours. The depth profile analyses also revealed silver and gold segregation to the surface of the alloys; preferential location of Au on the alloys surface may be related to their resistance to bulk sulfide formation. In preliminary tests, a PdAgAu alloy membrane displayed higher initial H{sub 2} permeability than a similarly prepared pure Pd sample and, consistent with resistance to bulk sulfide formation, lower permeability loss in H<sub>2sub>S than pure Pd.

  8. Fabrication of heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalyst and efficient photodegradation of organic contaminants under visible-light

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Meng; Li, Shuangli; Yan, Tao; Ji, Pengge; Zhao, Xia; Yuan, Kun; Wei, Dong [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Du, Bin, E-mail: dubin61@gmail.com [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

    2017-07-05

    Highlights: • The product shows efficient activity in photodegradation of RhB, BPA, and phenol. • The BBOC-10 heterojunction exhibits the best activity under visible light. • Suppressed recombination of photo-generated carriers lead to the activity enhancement. - Abstract: Heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalysts were fabricated by a facile one-pot hydrothermal method, in which melem served as the sacrificial reagent to supply carbonate anions. The as-synthesized Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction catalysts were characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscope. The XRD patterns of Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} catalysts showed the distinctive peaks of Bi{sub 2}O{sub 2}CO{sub 3} and Bi{sub 2}O{sub 4}. The SEM and TEM results showed that the pure Bi{sub 2}O{sub 2}CO{sub 3} possessed large plate morphology, while Bi{sub 2}O{sub 4} were composed of various nanorods and particles. As for Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction, it was obviously observed that Bi{sub 2}O{sub 4} nanorods and particles were grown on the surfaces of Bi{sub 2}O{sub 2}CO{sub 3} plates. The visible light driven photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction photocatalyst was evaluated by decomposing dyes, phenol, and bisphenol A in water. Compared with Bi{sub 2}O{sub 2}CO{sub 3} and Bi{sub 2}O{sub 4}, the Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalysts have exhibited remarkable enhanced activity under visible light. The excellent activity can be mainly attributed to the enhanced separation efficiency of photo-generated carriers. Controlled experiments using different radical scavengers proved that ·O{sub 2}{sup −} and h{sup +} played the main role in decomposing organic pollutants. The results of this work would

  9. Temperature dependence of NGR Cu(2) line width in YBa sub 2 Cu sub 3 O sub 7 sub - sub y

    CERN Document Server

    Duglav, A V; Sakhratov, Y A; Savinkov, A V

    2001-01-01

    One conducted systematic measurements of sup 6 sup 3 Cu(2) NGR line width using underdoped YBa sub 2 Cu sub 3 O sub 7 sub - sub y specimens within 4.2 K < T < 300 K temperature range. It is shown that as temperature drops below the critical one the width of copper NGR line becomes wider monotonically which temperature dependence resembles behavior of superconducting slit. The observed behavior is associated with energy dependence of condensate of moving current-charge states like waves of charged density on phase of order parameter which according to the calculations occurs at T < T sub c only. The obtained quantitative evaluations of line winding at T< T sub c conform to the measurement results

  10. Nanocrystallization and magnetic anisotropy in Co{sub 66}Si{sub 16}B{sub 12}Fe{sub 4}Mo{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, J.A. [Dep. de Fisica, Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Rivas, M. [Dep. de Fisica, Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain)]. E-mail: rivas@uniovi.es; Tejedor, M. [Dep. de Fisica, Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Svalov, A. [Dep. de Fisica, Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Pierna, A.R. [Dep. de Ingenieria Quimica y Medio Ambiente, Universidad del Pais Vasco, PO Box 1379, 20080 San Sebastian (Spain); Marzo, F.F. [Dep. de Ingenieria Quimica y Medio Ambiente, Universidad del Pais Vasco, PO Box 1379, 20080 San Sebastian (Spain)

    2005-04-15

    A study of the magnetic anisotropy originated by the nanocrystallization of the amorphous Co{sub 66}Si{sub 16}B{sub 12}Fe{sub 4}Mo{sub 2} is presented. Mechanically polished samples of this alloy were submitted to various thermal treatments to obtain different degrees of crystallization. The results show that an homogeneous distribution of nanocrystallites of about 10nm originates a magnetic anisotropy of 18Jm{sup -3} while the larger crystals that appear, due to the coalescence of the small crystallites, with annealings over 500 deg. C produce an increase of the magnetic anisotropy up to values of about 100Jm{sup -3}, that are similar to the ones of the as-quenched material. From the value of the effective magnetic anisotropy constant we deduce that in the samples annealed below the onset temperature, the majority of the crystallites are of Co{sub 2}B and Co{sub 3}B.

  11. The thermal properties of amorphous Fe{sub 40}Pd{sub 40}B{sub 20} and Fe{sub 60}Pd{sub 20}B{sub 20} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yuan-Tsung, E-mail: ytchen@yuntech.edu.tw

    2015-07-15

    The thermal stability of FePdB thin films was studied using nonisothermal and isothermal analyses. X-ray diffraction (XRD) patterns indicated that Fe{sub 40}Pd{sub 40}B{sub 20} and Fe{sub 60}Pd{sub 20}B{sub 20} films with thicknesses in the range 25–75 Å were amorphous, whereas Fe{sub 40}Pd{sub 40}B{sub 20} and Fe{sub 60}Pd{sub 20}B{sub 20} films with thicknesses in the range 100–200 Å exhibited a nanocrystalline FePd (111) structure. The crucial glass forming ability index (γ and γ{sub m}) was determined using the differential scanning calorimetry (DSC) results of amorphous FePdB films. The Kissinger formula was applied to calculate the activation energy (Q) of crystallization for determining the resistance of the films to crystallization. Thermal analysis showed that the thermal stability and incubation time of Fe{sub 40}Pd{sub 40}B{sub 20} are more favorable than those of Fe{sub 60}Pd{sub 20}B{sub 20}. - Highlights: • FePdB films were amorphous in the range 25–75 Å. • FePdB films exhibited a FePd (111) structure in the range 100–200 Å. • The crucial glass forming ability index was determined using the DSC. • Kissinger formula was applied to calculate the activation energy of crystallization. • The thermal performance of Fe{sub 40}Pd{sub 40}B{sub 20} is more favorable than Fe{sub 60}Pd{sub 20}B{sub 20}.

  12. Theoretical investigations of Co{sub 2}Mn{sub 1-x}Cr{sub x}Sn and Co{sub 2}MnSn{sub 1-y}Si{sub y} pseudo-ternary alloys: First principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Charifi, Z., E-mail: charifizoulikha@gmail.com [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Hamad, B. [Physics Department, The University of Jordan, Amman 11942 (Jordan); Physics Department, University of Arkansas, 825 W. Dickson St., Fayetteville, AR 72701 (United States); Baaziz, H. [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Soyalp, F. [Yüzüncü Yıl University, Faculty of Education, Department of Physics, Van 65080 (Turkey)

    2015-11-01

    The electronic and magnetic properties of Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn and Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys are investigated using density functional theory (DFT) within a full-potential linearized augmented-plane-wave (FP-LAPW) method. Amongst the systems under investigation, Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys show half metallicity with 100% spin polarization at the Fermi level, however Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn are found to be pseudo-half metals with few minority states at the Fermi level and high spin polarization. The substitution of Si with Sn keeps the magnetic moment constant in Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys, whereas the substitution of Mn with Cr decreases the magnetic moment and degrade the half-metallicity in Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn alloys. The Curie temperature is calculated and it is found to be about 928 K for all Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys, whereas it decreases linearly with x for Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn alloys. The lattices constants, bulk modulii, energy gaps, polarization ratio and density of states are calculated and their variation versus x or y are discussed. - Highlights: • The band structure calculations show that Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys are half-metallic ferromagnets. • The effect of substituting Sn by Si is a slight change in the position of the Fermi level and an increase in the band gap. • For Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn alloys, the results suggest that there is a finite density of states in the minority-spin d band of manganese. • The Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn compounds cannot be classified as half-metallic ferromagnets. • The substitution of Mn with Cr decreases the magnetic moment per formula unit from 5.0 to 4.0µ{sub B}.

  13. First Measurement of the Ratio of Branching Fractions Β(Λ<sub>b> → Λ<sub>csub>+μ-¯ν<sub>μ)/Β(Λb> → Λ<sub>c>+π-) at CDF II

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shin-Shan [Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Physics and Astronomy

    2005-01-01

    We present the first measurement of the ratio of branching fractions Β(Λ<sub>b> → Λ<sub>csub>+μ-¯ν<sub>μ)/Β(Λb> → Λ<sub>c>+π-) based on 171.5 pb-1 of p¯p collisions at √s = 1.96 TeV taken with the CDF-II detector. In addition, we present measurements of Β(¯Β0 → D*+μ-¯ν<sub>μ>)/Β(¯Β0 → D*+π-) and Β(¯Β0 → D+μ-¯ν<sub>μ>/Β(¯Β0 → D+π-), which serve as control samples to understand the data and Monte Carlo used for the Λ<sub>b> analysis.

  14. Dissipation mechanism in a high-T{sub c} Bi{sub 1.7}Pb{sub 0.3}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} granular superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Bhalla, G.L.; Pratima; Malik, Amita; Singh, K.K

    2003-08-01

    Magneto-resistance studies in a high-T{sub c} granular superconductor Bi{sub 1.7}Pb{sub 0.3}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} in an applied magnetic field ranging from 0 to 0.6 T in the low current limits (1 mA) have been carried out to understand the dissipation mechanism in high-T{sub c} superconducting materials. The Kosterlitz-Thouless (KT) as well as the Ambegaoker-Halperin (AH) widely employed models are invoked to interpret the results. The KT theory is found to account for dissipation in the temperature range T{sub KT}sub GL}, i.e. between the Kosterlitz-Thouless temperature and the Ginzberg-Landau transition temperature. The dissipation around T{sub c} cannot be explained adequately. It is suggested that dissipation in the entire range of temperature can be accounted for on the basis of a modified Ambegaokar-Halperin theory incorporating two mechanisms, viz. vortex-dynamics and the fluctuations of the order parameter and the two mechanisms crossover at a transition temperature (T{sub BP})

  15. Lattice energies and polarizabilities of lanthanide gallium garnets (Ln{sub 3}Ga{sub 5}O{sub 12})

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Dimitar, E-mail: petrov_d_n@abv.bg [Department of Physical Chemistry, University of Plovdiv “Paisii Hilendarski”, 24, Tsar Asen Str., 4000 Plovdiv (Bulgaria)

    2013-04-10

    Highlights: ► The lattice energies Δ{sub L}H{sup θ} of Ln{sub 3}Ga{sub 5}O{sub 12} are determined by the Born–Haber cycle. ► The Born–Haber cycle yields the lowest values among three applied methods. ► Molar polarizations P{sub m} of Ln{sub 3}Ga{sub 5}O{sub 12} have been calculated by the Debye equation. ► The derivative (∂Δ{sub L}H{sup θ}/∂P{sub m}) corresponds to the shear moduli of these crystals. - Abstract: Lattice energies Δ{sub L}H{sup θ} of lanthanide gallium garnets Ln{sub 3}Ga{sub 5}O{sub 12} (Ln = Nd–Lu) have been determined from the Born–Haber thermochemical cycle and compared with those previously obtained by atomistic simulations in the Born model or calculated by an empirical equation. The Born–Haber cycle yields the lowest values among the three methods. Molar polarizations P{sub m} of Ln{sub 3}Ga{sub 5}O{sub 12} have been calculated by the Debye equation. It has been found that the partial derivative (∂Δ{sub L}H{sup θ}/∂P{sub m}) corresponds by magnitude to the shear moduli of these crystals.

  16. Photoelectrochemistry of Co/sub 3/O/sub 4/ and PbO/sub 2/ sputtered electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Vigneron, J.; Redon, A.M.; Heindl, R.; Martin, J.C.; Sella, C.

    1981-12-01

    Some preliminary results on sputtered electrodes of Co/sub 3/O/sub 4/ (p type) and PbO/sub 2/ (n type) semiconductors are given. Photodissolution was observed in 1 M NaOH. Sodium polysulphide could stabilize both compounds, but hydroquinone could stabilize Co/sub 3/O/sub 4/ only.

  17. Growth and characterization of acentric BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Szymborska-Małek, Katarzyna; Gągor, Anna [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Majchrowski, Andrzej [Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland)

    2015-05-15

    Growth, single crystal X-ray diffraction, polarized Raman and infrared (IR) studies of BaHf(BO{sub 3}){sub 2} are presented. Raman and IR spectra of polycrystalline BaZr(BO{sub 3}){sub 2} are also reported to facilitate assignment of modes. BaHf(BO{sub 3}){sub 2} borate crystallizes in trigonal system, space group R3c, with lattice parameters: a=5.1540(4) Å, c=33.901(3) Å. It accommodates dolomite-like structure doubled in the c direction, which is built of alternating layers of HfO{sub 6} octahedra and BaO{sub 6} distorted trigonal prisms that are connected through borate groups. The obtained structural as well as spectroscopic data show that BaHf(BO{sub 3}){sub 2} is isostructural with BaZr(BO{sub 3}){sub 2} and the deviations from centrosymmetry is small. - Graphical abstract: Arrangement of BO{sub 3} groups in BaHf(BO{sub 3}){sub 2} along the c direction in one unit cell. Dark and light blue denote different borate groups. - Highlights: • BaHf(BO{sub 3}){sub 2} single crystals were grown. • X-ray diffraction showed that this borate crystallizes in the acentric R3c structure. • Raman and IR spectra were measured for BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}, respectively. • Assignment of modes is proposed.

  18. The Dopants and Doping Level Dependence of the Structure and Magnetic Properties of the Eu (BA<sub>1-xsub>LRx)>2sub>Cu>3sub>O>7+δsub>

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yu [Iowa State Univ., Ames, IA (United States)

    2002-12-31

    Eu(Ba<sub>1-xsub>LRx)>2sub>Cu>3sub>O>7+δsub> were systematically studied in order to understand how the valence of the rear earth elements, ionic sizes and magnetic moment affect the crystal structure and magnetic and electrical properties. Differential thermal analyses were carried out to check the phase purity, X-ray data were least-squares fitted to determine the lattice parameters, and DC-SQUID magnetometry was used to characterize the superconducting properties. These results showed that the crystallography is consistent with other EuLR123ss series, LR = La, Pr, Eu. The lattice parameters vary with the ionic radii of the rare earth ions. Unlike the uniform change in lattice parameter, the superconducting transition did not vary systematically with the ionic size of the dopants. Although the general trend was for T<sub>c> to decrease with decreasing ionic size of the dopant, for the same doping level, Pr was anomalous, depressing T<sub>c> faster. Although the exact mechanism is not clear, this result is consistent with the depression of T<sub>c> for Pr substitution for the rare earth in R123. The critical current J<sub>c> was determined using the Bean model from magnetization versus field measurements as a function of temperature and field. The effect of the dopants on J<sub>c> with the increasing of temperature or applied field was determined. For T < 77 K and small values of x, the value of J<sub>c> was increased over that of the x = 0 sample. In addition, the smaller the substituting atom, the higher the J<sub>c> becomes. For instance, at x = 0.025, Eu123 < EuLa.025 < EuPr.025 < EuNd.025 < EuEu.025. The enhancement of J<sub>c> disappears for x > 0.05 and T > 0.5T<sub>c>.

  19. Thermal and mechanical properties of AgPb{sub 9}(VO{sub 4}){sub 6}I and AgBa{sub 9}(VO{sub 4}){sub 6}I

    Energy Technology Data Exchange (ETDEWEB)

    Uno, Masayoshi; Kosuga, Atsuko; Masuo, Sumiko; Imamura, Mitsuhiro; Yamanaka, Shinsuke

    2004-12-14

    AgPb{sub 9}(VO{sub 4}){sub 6}I and AgBa{sub 9}(VO{sub 4}){sub 6}I were synthesized as a potential waste form to immobilize radioactive iodine. The thermal and mechanical properties such as the Young's modulus and thermal conductivity were measured. The crystal systems of AgBa{sub 9}(VO{sub 4}){sub 6}I and AgPb{sub 9}(VO{sub 4}){sub 6}I are rhombohedral and monoclinic, respectively. They are stable up to 950 K under Ar atmosphere. The thermal conductivity of the samples is less than 1.0 W m{sup -1} K{sup -1}, which is lower than that of borosilicate glasses used for high-level nuclear waste forms.

  20. Epitaxial growth of an Sm{sub 2}O{sub 3} buffer layer for EuBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Y. [Faculty of Engineering, Iwate University, Ueda 4-chome 3-5, Morioka-shi, Iwate 020-8551 (Japan)]. E-mail: t3304010@iwate-u.ac.jp; Ota, Y. [Faculty of Engineering, Iwate University, Ueda 4-chome 3-5, Morioka-shi, Iwate 020-8551 (Japan); Michikami, O. [Faculty of Engineering, Iwate University, Ueda 4-chome 3-5, Morioka-shi, Iwate 020-8551 (Japan)

    2006-10-01

    Fabrication of EBCO thin films with a high critical current density (J {sub c}) on an Sm{sub 2}O{sub 3} buffer layer was carried out. The J {sub c} values were influenced by surface roughness (R {sub z}) of Sm{sub 2}O{sub 3} and EBCO films. To reduce R {sub z} of Sm{sub 2}O{sub 3} buffer layers, the effect of target-substrate distance (D {sub off}) on surface morphology was examined. The critical temperature (T {sub ce}) was always almost 90 K regardless of D {sub off} in the Sm{sub 2}O{sub 3} buffer layer deposition. The J {sub c} values of EBCO thin films deposited on Sm{sub 2}O{sub 3} buffer layers with a smooth surface were 6.4 MA/cm{sup 2} at 77.3 K.

  1. Structural and controllable thermal expansion properties of Sc{sub 2−x}Al{sub x}Mo{sub 3}O{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Meimei, E-mail: mmwu@ciae.ac.cn [China Institute of Atomic Energy, Beijing 102413 (China); Peng, Jie [Experimental Physics Center, Institute of High Energy Physics, CAS, Beijing 100049 (China); Cheng, Yingzhi [College of Chemical Engineering, Shandong University of Technology, Zibo 255049 (China); Xiao, Xiaoling [College of Materials and Photoelectric Technology, Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Dongfeng, E-mail: dongfeng@ciae.ac.cn [China Institute of Atomic Energy, Beijing 102413 (China); Hu, Zhongbo [College of Materials and Photoelectric Technology, Graduate University of Chinese Academy of Sciences, Beijing 100049 (China)

    2013-11-15

    Highlights: •Monophasic solid solutions Sc{sub 2−x}Al{sub x}Mo{sub 3}O{sub 12} have been prepared in the whole composition range. •The cell parameters decrease with increasing Al content. •Fe substitution induces the thermal expansion property of Sc{sub 2−x}Al{sub x}Mo{sub 3}O{sub 12} controllable. •Sc{sub 1.7}Al{sub 0.3}Mo{sub 3}O{sub 12} exhibits zero thermal expansion in 600–800 °C temperature range. -- Abstract: The crystal structure and thermal expansion properties of solid solutions Sc{sub 2−x}Al{sub x}Mo{sub 3}O{sub 12} (x = 0.0–2.0) are systematically investigated by X-ray diffraction. Rietveld refinement results indicate that samples with x ⩽ 1.3 crystallize in a Sc{sub 2}Mo{sub 3}O{sub 12}-type orthorhombic (Pnca) structure, whereas others have an Al{sub 2}Mo{sub 3}O{sub 12}-type monoclinic (P2{sub 1}/a) structure. Substitution of 15% Al{sup 3+} for Sc{sup 3+} leads to a rapid change in linear thermal expansion coefficient from −2.334 × 10{sup −6} °C{sup −1} to −0.732 × 10{sup −6} °C{sup −1}. The thermal expansion coefficients of Sc{sub 2−x}Al{sub x}Mo{sub 3}O{sub 12} monotonously increase with increased Al{sup 3+} content.

  2. Magnetically separable mesoporous Fe{sub 3}O{sub 4}/silica catalysts with very low Fe{sub 3}O{sub 4} content

    Energy Technology Data Exchange (ETDEWEB)

    Grau-Atienza, A.; Serrano, E.; Linares, N. [Molecular Nanotechnology Laboratory, Department of Inorganic Chemistry, University of Alicante, Carretera San Vicente s/n, E-03690 Alicante (Spain); Svedlindh, P. [Department of Engineering Sciences, Uppsala University, Box 534, SE-75121 Uppsala (Sweden); Seisenbaeva, G., E-mail: Gulaim.Seisenbaeva@slu.se [Department of Chemistry and Biotechnology, BioCenter SLU, Box 7015, SE-75007 Uppsala (Sweden); García-Martínez, J., E-mail: j.garcia@ua.es [Molecular Nanotechnology Laboratory, Department of Inorganic Chemistry, University of Alicante, Carretera San Vicente s/n, E-03690 Alicante (Spain)

    2016-05-15

    Two magnetically separable Fe{sub 3}O{sub 4}/SiO{sub 2} (aerogel and MSU-X) composites with very low Fe{sub 3}O{sub 4} content (<1 wt%) have been successfully prepared at room temperature by co-condensation of MPTES-functionalized Fe{sub 3}O{sub 4} nanoparticles (NPs) with a silicon alkoxide. This procedure yields a homogeneous incorporation of the Fe{sub 3}O{sub 4} NPs on silica supports, leading to magnetic composites that can be easily recovered using an external magnetic field, despite their very low Fe{sub 3}O{sub 4} NPs content (ca. 1 wt%). These novel hybrid Fe{sub 3}O{sub 4}/SiO{sub 2} materials have been tested for the oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) with hydrogen peroxide showing an enhancement of the stability of the NPs in the Fe{sub 3}O{sub 4}/silica aerogel as compared to the Fe{sub 3}O{sub 4} NPs alone, even after five catalytic cycles, no leaching or agglomeration of the Fe{sub 3}O{sub 4}/SiO{sub 2} systems. - Graphical abstract: Novel magnetically separable mesoporous silica-based composites with very low magnetite content. - Highlights: • An innovative way to prepare magnetically separable composites with <1 wt% NPs. • The Fe{sub 3}O{sub 4}/silica composites are readily magnetized/demagnetized. • The Fe{sub 3}O{sub 4}/silica composites can be easily recovered using an external magnetic field. • Excellent catalytic performance and recyclability despite the low Fe{sub 3}O{sub 4} NPs content.

  3. A 3d-4f complex constructed by the assembly of a cationic template, [Cu(en){sub 2}]{sup 2+}, and a 3D anionic coordination polymer, [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}(C{sub 5}O{sub 5})(H{sub 2}O){sub 2}]{sup 2-}

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Szu-Yu; Yeh, Chang-Tsung; Wang, Chih-Chieh [Department of Chemistry, Soochow University, Taipei, Taiwan (China); Lee, Gene-Hsiang [Instrumentation Center, National Taiwan University, Taipei, Taiwan (China); Sheu, Hwo-Shuenn [National Synchrotron Radiation Research Center, Hsinchu, Taiwan (China)

    2017-05-18

    A three-dimensional (3D) 3d-4f complex, [Cu(en){sub 2}][Sm{sub 2}(C{sub 5}O{sub 5})(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 2}].8H{sub 2}O (1) (en = ethylenediamine, C{sub 5}O{sub 5}{sup 2-} = dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione), were prepared via the in-situ ring-opening oxidation reaction of croconate in the presence of the template-directed complex, [Cu(en){sub 2}]{sup 2+} cation. The structural characterization determined by X-ray diffraction determination reveals that the 3D anionic coordination polymer of [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}(C{sub 5}O{sub 5})(H{sub 2}O){sub 2}]{sup 2-} in 1 can be describe in terms of in-plane 2D honeycomb-like [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}] layered frameworks bridged by oxalate with bis-chelating mode, being mutually interlinked via the bridge of μ{sub 1,2,3,4}-croconate ligands with bis-chelating coordination mode to complete the 3D open framework, which gives rise to 1D channels with pore size of 14.023 x 11.893 Aa (longest atom-atom contact distances) along the b axis. The structure-directing complex, [Cu(en){sub 2}]{sup 2+}, and solvated water molecules are resided into these honeycomb-type hexagonal channels. The thermal stability of 1 was further studied by TGA and in-situ powder X-ray diffraction measurement. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Superconducting properties of EuBa{sub 2}Cu{sub 3}O{sub 7} thin films on thick Sm{sub 2}O{sub 3} buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Y. [Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka-shi, Iwate 020-8551 (Japan)], E-mail: t5306002@iwate-u.ac.jp; Ota, Y.; Michikami, O. [Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka-shi, Iwate 020-8551 (Japan)

    2007-10-01

    There has been a tendency for micro-cracks to be generated in superconducting films deposited on R-Al{sub 2}O{sub 3} substrates with buffer layers. Thickening the buffer layer is one method for suppressing the generation of micro-cracks. When Sm{sub 2}O{sub 3} buffer layers were thickened, surface roughness (R{sub z}) of Sm{sub 2}O{sub 3} and EuBa{sub 2}Cu{sub 3}O{sub 7} (EBCO) films increased and the critical current density (J{sub c}) deteriorated with increase in Sm{sub 2}O{sub 3} buffer layer thickness (t{sub Sm}). Then, the improvement of Sm{sub 2}O{sub 3} buffer layers on surface morphology and increment of J{sub c} of EBCO thin films deposited on the thick Sm{sub 2}O{sub 3} buffer layers were carried out. The surface roughness (R{sub z}) of Sm{sub 2}O{sub 3} buffer layers became small by optimizing sputtering conditions. R{sub z} of EBCO thin films decreased depending on that of Sm{sub 2}O{sub 3} buffer layers. The critical temperature (T{sub ce}) was 90 K and J{sub c} showed a high value of 1.6 MA/cm{sup 2} at 77.3 K when t{sub Sm} was 2000 A.

  5. Exploring the thermoelectric and magnetic properties of uranium selenides: Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Azam, Sikander; Khan, Saleem Ayaz [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 30614 Pilsen (Czech Republic); Din, Haleem Ud [Department of Physics, Hazara University, Mansehra (Pakistan); Khenata, Rabah [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria); Goumri-Said, Souraya, E-mail: sosaid@alfaisal.edu [College of Science, Physics department, Alfaisal University, P.O. Box 50927, Riyadh 11533 (Saudi Arabia)

    2016-09-01

    The electronic, magnetic and thermoelectric properties of Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6} compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin–orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6} respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl{sub 3}Cu{sub 4}USe{sub 6} is more suitable for thermoelectric device applications than Tl{sub 2}Ag{sub 2}USe{sub 4}. - Highlights: • Electronic, magnetic and thermoelectric properties of uranium selenides are investigated with DFT. • They show a narrow direct energy band gap of 0.7 and 0.875 eV. • U-d/f states are responsible for electrical transport properties. • Tl{sub 3}Cu{sub 4}USe{sub 6} is more suitable for thermoelectric device applications than Tl{sub 2}Ag{sub 2}USe{sub 4}.

  6. Field-induced variations of the microwave surface impedance of YBa{sub 2}Cu{sub 3}O{sub 7} crystals near T{sub c}

    Energy Technology Data Exchange (ETDEWEB)

    Agliolo Gallitto, A.; Ciccarello, I.; Guccione, M.; Li Vigni, M.; Persano Adorno, D. [Istituto Nazionale di Fisica della Materia, Unita di Palermo and Istituto di Fisica dellUniversita, Via Archirafi 36, I-90123 Palermo (Italy)

    1997-09-01

    The microwave surface impedance Z{sub s} of a YBa{sub 2}Cu{sub 3}O{sub 7} single crystal is investigated as a function of the magnetic field H{sub 0} at different temperatures close to T{sub c}. It is shown that Z{sub s} depends on H{sub 0} for applied fields higher as well as lower than H{sub c1}. A model is discussed in which the field dependence of Z{sub s} below H{sub c1} is ascribed to the field-induced variations, within the penetration depth, of the partial concentrations of both normal and condensate electrons. The field dependence of Z{sub s} above H{sub c1} is explained using the Coffey and Clem model. {copyright} {ital 1997} {ital The American Physical Society}

  7. Frequency dependent ac magnetic susceptibility in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}/La{sub 1/3}Ca{sub 2/3}MnO{sub 3}/La{sub 2/3}Ca{sub 1/3}MnO{sub 3} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gross, K. [Grupo de Ingenieria de Nuevos Materiales, Departamento de Fisica, Universidad del Valle, A.A. 25360 Cali (Colombia); Moran, O. [Laboratorio de Materiales Ceramicos y Vitreos, Departamento de Fisica, Universidad Nacional de Colombia sede Medellin, A.A. 568 Medellin (Colombia)], E-mail: omoranc@unalmed.edu.co; Baca, E. [Grupo de Ingenieria de Nuevos Materiales, Departamento de Fisica, Universidad del Valle, A.A. 25360 Cali (Colombia)

    2007-12-01

    The field frequency dependence of the ac magnetic susceptibility in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}/-La{sub 1/3}Ca{sub 2/3}MnO{sub 3}/La{sub 2/3}Ca{sub 1/3}MnO{sub 3} structures was studied. The trilayers were grown in situ on (0 0 1)-oriented SrTiO{sub 3} substrates using a dc sputtering technique. The ac magnetic susceptibility measurements were performed using an inductive technique with exciting field amplitude h{sub ac} = 0.1 Oe, applied parallel to (0 0 1)-direction of the substrate. The signal frequency was varied between 1 and 51.1 kHz. The YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}/-La{sub 1/3}Ca{sub 2/3}MnO{sub 3}/-La{sub 2/3}Ca{sub 1/3}MnO{sub 3} trilayers displayed a diamagnetic behavior below the superconducting critical temperature T{sub c} ({approx}77 K) and a combined effect, probably stemming from a complex interplay between the ferromagnetic and antiferromagnetic character of the constituents La{sub 2/3}Ca{sub 1/3}MnO{sub 3} and La{sub 1/3}Ca{sub 2/3}MnO{sub 3}, at T > T{sub c}. The observed Curie temperature T{sub c} of {approx}260 K was associated with the F-layer. The imaginary branch of the magnetic susceptibility showed loss peaks pinned at 72 K, which was independent of frequency. This temperature was found to be very close to the irreversibility temperature, T{sub I}, which separates the creep and flux flow regimens. The T{sub I} was obtained using the Joennson model, which was applied to the real branch of the measured magnetic susceptibility. According to this model, {chi}{sup '}(T,f,h{sub ac})=K(T,h{sub ac})f{sup 3S(T,h{sub ac})/2}, where f stands for the measuring frequency and S = k{sub B}T/U{sub eff} for the vortex relaxation rate with U{sub eff} being the effective vortex pinning energy. Farther, K(T, h{sub ac}) is a factor which depends on the critical current density J{sub c} . Additionally, U{sub eff} was obtained by measuring the resistance of the YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} layer in the YBa{sub 2}Cu{sub 3}O{sub 7

  8. Dispersion of CEF levels in Nd{sub 2}CuO{sub 4} and Pr{sub 0.86}Ce{sub 0.14}CuO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Henggeler, W.; Furrer, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Chattopadyay, T.; Roessli, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France)

    1997-09-01

    We performed inelastic scattering experiments to determine the dispersion of the {Gamma}{sub 6}{sup (1)}-{Gamma}{sub 6}{sup (2)}-Nd crystal field excitation in Nd{sub 2}CuO{sub 4} and of the {Gamma}{sub 4}-{Gamma}{sub 5} Pr CEF excitation in Pr{sub 1.86}Ce{sub 0.14}CuO{sub 4}. Our results can be described within the random phase approximation model. (author) 4 figs.

  9. Effect of rutile TiO{sub 2} on the photocatalytic performance of g-C{sub 3}N{sub 4}/brookite-TiO{sub 2-x}N{sub y} photocatalyst for NO decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huihui, E-mail: lihh@lzu.edu.cn [Key Laboratory for Magnetism Magnetic Materials of the Ministry of Education, Lanzhou University, 222 south Tianshui Road, Lanzhou, 730000 (China); Wu, Xiaoyong [Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Yin, Shu [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Katsumata, Kenichi [Photocatalysis International Research Center, Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510 (Japan); Wang, Yuhua [Key Laboratory for Magnetism Magnetic Materials of the Ministry of Education, Lanzhou University, 222 south Tianshui Road, Lanzhou, 730000 (China)

    2017-01-15

    Graphical abstract: g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}Ny forms a Z-scheme photocatalytic system, which shows improvement on the photocatalytic activity than that of g-C{sub 3}N{sub 4}/single brookite TiO{sub 2-x}N{sub y}. - Highlights: • g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} forms a Z-scheme photocatalytic system. • Photogenerated electrons can efficiently transfer from rutile TiO{sub 2} to g-C{sub 3}N{sub 4}. • Single brookite TiO{sub 2-x}N{sub y} shows lower photo-utilization efficiency than rutile-brookite mixed one. • DeNO{sub x} activities of brookite TiO{sub 2-x}N{sub y} hybrids decrease with g-C{sub 3}N{sub 4} amount increase. - Abstract: Novel g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} composite photocatalysts were fabricated through a facile solvothermal approach. The effect of rutile phase TiO{sub 2} with brookite TiO{sub 2} and g-C{sub 3}N{sub 4} on the photocatalytic activity of g-C{sub 3}N{sub 4}/nitrogen-doped TiO{sub 2} composite was studied. The photocatalytic performance of the photocatalyst was evaluated by measuring the degradation of NO gas under visible and UV light irradiation. It is suggested that g-C{sub 3}N{sub 4}/rutile-brookite TiO{sub 2-x}N{sub y} forms a Z-scheme photocatalytic system, which shows improvement on the photocatalytic activity than that of g-C{sub 3}N{sub 4}/single brookite TiO{sub 2-x}N{sub y}. By importing rutile phase TiO{sub 2-x}N{sub y}, the photogenerated electrons can efficiently transfer from rutile TiO{sub 2} to g-C{sub 3}N{sub 4}, which results in the separation of electron and hole pairs, enhancing the photocatalytic ability. However, single brookite TiO{sub 2-x}N{sub y} can not remove the photogenerated electrons efficiently and the photocatalytic performances of composites decrease with g-C{sub 3}N{sub 4} amount increase.

  10. Growth and spectroscopic properties of Nd{sup 3+}-doped Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Wang [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Department of Physics, Huainan Normal University, Huainan, Anhui 232001 (China); Lin Zhoubin; Zhang Lizhen [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Wang Guofu, E-mail: wgf@ms.fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2011-02-10

    Research highlights: > In this paper we grow Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystals by the Czochralski method and study spectroscopic properties of Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystal. > We find that Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystal has high fluorescence quantum efficiency. > Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystal can be considered as a new potential laser gain medium for the diode laser pumping. - Abstract: This paper reports the growth and spectral properties of Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystals. An Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystal with dimensions of O20 x 25 mm{sup 3} has been grown by the Czochralski method. The spectroscopic properties of Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystal were investigated. The Judd-Ofelt theory was applied to calculate the spectral parameters. The polarized absorption cross-sections of Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystal are 4.25 x 10{sup -20} cm{sup 2} with full width at half maximum (FWHM) of 14.6 nm for the {pi}-polarization and 2.87 x 10{sup -20} cm{sup 2} with FWHM of 16.2 nm for the {sigma}-polarization, respectively. The emission cross-sections are 10.0 x 10{sup -20} cm{sup 2} at 1060 nm for {pi}-polarization and 13.6 x 10{sup -20} cm{sup 2} at 1067 nm for {sigma}-polarization, respectively. The fluorescence quantum efficiency has been estimated to be 90.0%. Nd{sup 3+}:Na{sub 2}Gd{sub 4}(MoO{sub 4}){sub 7} crystal may be considered as a potential laser gain medium for the diode laser pumping.

  11. Ce{sub 2}PdIn{sub 8}, Ce{sub 3}PdIn{sub 11} and Ce{sub 5}Pd{sub 2}In{sub 19}—members of homological series based on AuCu{sub 3}- and PtHg{sub 2}-type structural units

    Energy Technology Data Exchange (ETDEWEB)

    Tursina, A.; Nesterenko, S.; Seropegin, Y. [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Noël, H. [Laboratoire de Chimie du Solide et Matériaux, UMR6226 CNRS-Université de Rennes 1, Avenue du Général Leclerc, Rennes 30542 (France); Kaczorowski, D., E-mail: D.Kaczorowski@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O.Box 1410, Wrocław 50-950 (Poland)

    2013-04-15

    Crystal structures of three members of a unique homological series with the general formula Ce{sub m}Pd{sub n}In{sub 3m+2n} based on the AuCu{sub 3} and PtHg{sub 2} structure types were studied by single-crystal X-ray diffraction. The compounds crystallize with space group P4/mmm (Z=1) and the lattice parameters: a=4.6900(9) Å, c=12.185(6) Å for Ce{sub 2}PdIn{sub 8}, a=4.6846(8) Å, c=16.846(8) Å for Ce{sub 3}PdIn{sub 11}, and a=4.70120(10) Å, c=29.1359(4) Å for Ce{sub 5}Pd{sub 2}In{sub 19}. The crystal structures of Ce{sub 3}PdIn{sub 11} and Ce{sub 5}Pd{sub 2}In{sub 19} represent new types. The three structures constitute of [CeIn{sub 3}] cuboctahedra layers and [PdIn{sub 2}] rectangular polyhedra layers, alternating along the tetragonal c-axis in accordance with the m:n proportion. The magnetic and electrical transport properties of the novel compounds Ce{sub 3}PdIn{sub 11} and Ce{sub 5}Pd{sub 2}In{sub 19} were investigated down to 1.72 K. Both indides are Curie–Weiss paramagnets due to the presence of fairly well localized 4f electrons of trivalent cerium ions. The electrical resistivity of both materials is dominated over an extended temperature range by strong spin–flip Kondo interactions with the characteristic temperature scale of 20–30 K. - Graphical abstract: TOC Figure Crystal structures of Ce{sub 3}PdIn{sub 11}, Ce{sub 2}PdIn{sub 8}, and Ce{sub 5}Pd{sub 2}In{sub 19}. Highlights: ► Large section of Ce–Pd–In phase diagram was examined. ► Three distinct ternary phases were identified, two of them for the first time. ► Crystal structures of two novel compounds constitute new structure types. ► The determined crystal structures show close mutual relationship. ► Ce{sub 3}PdIn{sub 11} and Ce{sub 5}Pd{sub 2}In{sub 19} are paramagnetic Kondo lattices.

  12. Influence of doping in thermochromic V{sub 1−x}W{sub x}O{sub 2} and V{sub 1−x}Al{sub x}O{sub 2} thin films: Twice improved doping efficiency in V{sub 1−x}W{sub x}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Paone, Antonio, E-mail: antonio.paone@epfl.ch [Solar Energy and Building Physics Laboratory (LESO-PB), EPFL, CH-1015 Lausanne (Switzerland); Sanjines, Rosendo, E-mail: rosendo.sanjines@epfl.ch [Laboratory of Physics of Complex Matter (LPMC), EPFL, CH-1015 Lausanne (Switzerland); Jeanneret, Patrick, E-mail: patrick.jeanneret@he-arc.ch [University of Applied Sciences (HES-SO), Haute École Arc, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Whitlow, Harry J., E-mail: harry.whitlow@he-arc.ch [University of Applied Sciences (HES-SO), Haute École Arc, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Guibert, Edouard, E-mail: edouard.guibert@he-arc.ch [University of Applied Sciences (HES-SO), Haute École Arc, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Guibert, Geoffroy, E-mail: geoffroy.guibert@h-ne.ch [University of Applied Sciences (HES-SO), Haute École Arc, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Bussy, François, E-mail: francois.bussy@unil.ch [Institute of Mineralogy and Geochemistry (IMG), UNIL, CH-1015 Lausanne (Switzerland); Scartezzini, Jean-Louis, E-mail: jean-louis.scartezzini@epfl.ch [Solar Energy and Building Physics Laboratory (LESO-PB), EPFL, CH-1015 Lausanne (Switzerland); Schüler, Andreas, E-mail: andreas.schueler@epfl.ch [Solar Energy and Building Physics Laboratory (LESO-PB), EPFL, CH-1015 Lausanne (Switzerland)

    2015-02-05

    Highlights: • V{sub 1−x}W{sub x}O{sub 2} films were deposited by thermal evaporation using V-pellets in tungsten crucibles. • V{sub 1−x}W{sub x}O{sub 2} and V{sub 1−x}Al{sub x}O{sub 2} films were deposited by RF-reactive magnetron sputtering using V-target. • XRD analyses were performed on V{sub 1−x}W{sub x}O{sub 2} and V{sub 1−x}Al{sub x}O{sub 2} films. • The W-concentration in V{sub 1−x}W{sub x}O{sub 2} films was precisely determined by RBS investigations. • The doping efficiency in the present study is twice as effective as reported in literature. - Abstract: The parameters of thermal evaporation and magnetron sputtering deposition were optimized for fabrication of vanadium dioxide thin films. The O{sub 2} partial pressure during film deposition is critical for obtaining a pure VO{sub 2} phase. Thermochromic V{sub 1−x}W{sub x}O{sub 2} (x = 0.16 at.%) thin films were synthesized by thermal evaporation, while thermochromic VO{sub 2}, V{sub 1−x}W{sub x}O{sub 2} (x = 0.04 at.%, 0.12 at.%, 0.35 at.%) and V{sub 1−x}Al{sub x}O{sub 2} thin films were synthesized by magnetron sputtering. The structural properties of the deposited films were analyzed by X-Ray Diffraction (XRD), while their semiconductor-to-metal phase transitions were studied by electrical resistivity using the four-probe technique. Contamination from the crucible was shown by chemical analysis of the V{sub 1−x}W{sub x}O{sub 2} film deposited by thermal evaporation. Subsequent analyses of the films by Rutherford Backscattering Spectrometry (RBS), yielded doping efficiency of −49 ± 5°C/at.% and of −55 ± 7°C/at.% is respectively reported for films deposited by thermal evaporation and for films deposited by magnetron sputtering. These results suggest that the doping efficiency observed in the present study is twice as effective as previously reported in literature. X-ray diffraction analyses showed a progressive amorphization of the V{sub 1−x}Al{sub x}O{sub 2} films

  13. Exchange and crystal-field interactions in the antiferromagnets GdRh sub 2 Si sub 2 and TbRh sub 2 Si sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Szytula, A. (Inst. of Physics, Jagiellonian Univ., Cracow (Poland)); Radwanski, R.J.; Boer, F.R. de (Van der Waals-Zeeman Lab., Univ. van Amsterdam (Netherlands))

    1992-02-01

    Magnetization curves up to 35 T have been measured at 4.2 K on free powder particles of the antiferromagnets GdRh{sub 2}Si{sub 2} and TbRh{sub 2}Si{sub 2}. The magnetization process is analyzed within a two-sublattice model for antiferromagnets. For GdRh{sub 2}Si{sub 2} the intersublattice molecular-field coefficient amounts to 7.2 T f.u./{mu}{sub B}. For TbRh{sub 2}Si{sub 2} metamagnetic transitions at 8 and 15 T are observed. (orig.).

  14. Synthesis, crystal structure, and ionic conductivity of a new layered metal phosphate, Li{sub 2}Sr{sub 2}Al(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung-Chul; Kwak, Hyun-Jung [Department of Energy Systems Research, Ajou University, Suwon 16499 (Korea, Republic of); Yoo, Chung-Yul [Advanced Materials & Devices Laboratory, Korea Institute of Energy Research, Daejeon 34129 (Korea, Republic of); Yun, Hoseop [Department of Energy Systems Research, Ajou University, Suwon 16499 (Korea, Republic of); Kim, Seung-Joo, E-mail: sjookim@ajou.ac.kr [Department of Energy Systems Research, Ajou University, Suwon 16499 (Korea, Republic of)

    2016-11-15

    A new layered metal phosphate, Li{sub 2}Sr{sub 2}Al(PO{sub 4}){sub 3}, was synthesized in the form of either a single-crystal or polycrystalline powder using the molten hydroxide flux method or a solid-state reaction, respectively. Li{sub 2}Sr{sub 2}Al(PO{sub 4}){sub 3} crystallizes to the P2{sub 1}/n (Z=4) monoclinic space group with lattice parameters a≈4.95 Å, b≈22.06 Å, c≈8.63 Å, and β≈91.5°. The structure is composed of stacked [LiSrAl(PO{sub 4}){sub 2}] layers alternating regularly with [LiSrPO{sub 4}] layers. In the [LiSrAl(PO{sub 4}){sub 2}] sublattice, the AlO{sub 6} octahedra and PO{sub 4} tetrahedra are tilted cooperatively to form an anionic, corrugated, two-dimensional [Al(PO{sub 4}){sub 2}]{sup 3−} framework that can be regarded as a “distorted-glaserite” structure. The [LiSrPO{sub 4}] sublattice is that of a layered block containing a six-membered ring formed from alternating linkages of LiO{sub 4} and PO{sub 4} tetrahedra. The six-membered rings show a boat-type arrangement with the up(U) or down(D) pointing sequence, UUDUUD. The interspace between the two sublattices generates a two-dimensional pathway for Li{sup +} ion conduction. The impedance measurement indicated that Li{sub 2}Sr{sub 2}Al(PO{sub 4}){sub 3} had a moderate ion conductivity (σ≈1.30×10{sup −4} S cm{sup −1} at 667 K), with an activation energy E{sub a}≈1.02 eV. - Graphical abstract: Polyhedral view of Li{sub 2}Sr{sub 2}Al(PO{sub 4}){sub 3}. Li{sup +} ions are represented by green spheres, Sr atoms by white spheres, AlO{sub 6} groups by octahedra, and PO{sub 4} groups by tetrahedra. - Highlights: • New compound Li{sub 2}Sr{sub 2}Al(PO{sub 4}){sub 3} is reported. • The crystal structure is investigated by single-crystal XRD analysis. • The structure is formed by the alternate stacking of two different sublattices. • Correlation between the crystal structure and ionic conductivity is discussed.

  15. Nanocrystalline SiC and Ti<sub>3sub>SiC>2sub> Alloys for Reactor Materials: Diffusion of Fission Product Surrogates

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jiang, Weilin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-11-01

    MAX phases, such as titanium silicon carbide (Ti<sub>3sub>SiC>2sub>), have a unique combination of both metallic and ceramic properties, which make them attractive for potential nuclear applications. Ti<sub>3sub>SiC>2sub> has been suggested in the literature as a possible fuel cladding material. Prior to the application, it is necessary to investigate diffusivities of fission products in the ternary compound at elevated temperatures. This study attempts to obtain relevant data and make an initial assessment for Ti<sub>3sub>SiC>2sub>. Ion implantation was used to introduce fission product surrogates (Ag and Cs) and a noble metal (Au) in Ti<sub>3sub>SiC>2sub>, SiC, and a dual-phase nanocomposite of Ti<sub>3sub>SiC>2sub>/SiC synthesized at PNNL. Thermal annealing and in-situ Rutherford backscattering spectrometry (RBS) were employed to study the diffusivity of the variou