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Sample records for sb bi compounds

  1. Thermoelectric properties of quaternary (Bi,Sb){sub 2}(Te,Se){sub 3} compound

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    Lu, Pengfei, E-mail: photon.bupt@gmail.com [State Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876 (China); Li, Yiluan; Wu, Chengjie; Yu, Zhongyuan; Cao, Huawei; Zhang, Xianlong; Cai, Ningning; Zhong, Xuxia [State Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876 (China); Wang, Shumin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden)

    2014-01-25

    Highlights: • Sb and Se spin–orbit coupling play a key role in the band structure. • Substituted Bi/Sb and Te/Se have a limited impact on the transport coefficients. • n-Type doping will be preferred for quaternary (Bi,Sb){sub 2}(Te,Se){sub 3} compound. -- Abstract: The quaternary (Bi,Sb){sub 2}(Te,Se){sub 3} compounds are investigated using first-principles study and Boltzmann transport theory. The energy band structure and density of states are studied in detail. The electronic transport coefficients are then calculated as a function of chemical potential. The figure of merit ZT is obtained assuming a constant relaxation time and an averaged thermal conductivity. Our theoretical result agrees well with previous experimental data.

  2. Antiperovskite compounds SbNSr{sub 3} and BiNSr{sub 3}: Potential candidates for thermoelectric renewable energy generators

    Energy Technology Data Exchange (ETDEWEB)

    Bilal, M.; Saifullah,; Shafiq, M.; Khan, B. [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan); Rahnamaye Aliabad, H.A. [Department of Physics, Hakim Sabzevari University, Sabzevar (Iran, Islamic Republic of); Jalali Asadabadi, S. [Department of Physics, Faculty of Science, University of Isfahan (UI), 81744 Isfahan (Iran, Islamic Republic of); Ahmad, Rashid [Department of Chemistry, University of Malakand, Chakdara (Pakistan); Ahmad, Iftikhar, E-mail: ahma5532@gmail.com [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan)

    2015-01-23

    This letter communicates thermoelectric properties of antiperovskites SbNSr{sub 3} and BiNSr{sub 3}, using ab-initio calculations. These compounds are identified as good transport materials for their narrow band gaps and dense electronic states near their Fermi levels. The peak values of Seebeck coefficient of 1590 and 1540 μV/K are observed for SbNSr{sub 3} and BiNSr{sub 3}, respectively in the p-type regions, at room temperature. The figure of merit approaches unity for both materials, while their thermal conductivities increase and electrical conductivities decrease with temperature. These theoretical studies predict that these antiperovskites could be efficient materials for thermoelectric generators and need further experimental and theoretical studies. - Highlights: • We report theoretical studies of the thermoelectric properties of antiperovskites SbNSr{sub 3} and BiNSr{sub 3}. • Both of these compounds have direct band gap nature. • These compounds have narrow band gaps and dense electronic states near the Fermi levels. • They have large Seebeck coefficients and high values of the figure of merit at room temperature. • These properties demonstrate the effectiveness of SbNSr{sub 3} and BiNSr{sub 3} in thermoelectric devices.

  3. Antiperovskite compounds SbNSr3 and BiNSr3: Potential candidates for thermoelectric renewable energy generators

    Science.gov (United States)

    Bilal, M.; Saifullah; Shafiq, M.; Khan, B.; Rahnamaye Aliabad, H. A.; Jalali Asadabadi, S.; Ahmad, Rashid; Ahmad, Iftikhar

    2015-01-01

    This letter communicates thermoelectric properties of antiperovskites SbNSr3 and BiNSr3, using ab-initio calculations. These compounds are identified as good transport materials for their narrow band gaps and dense electronic states near their Fermi levels. The peak values of Seebeck coefficient of 1590 and 1540 μV/K are observed for SbNSr3 and BiNSr3, respectively in the p-type regions, at room temperature. The figure of merit approaches unity for both materials, while their thermal conductivities increase and electrical conductivities decrease with temperature. These theoretical studies predict that these antiperovskites could be efficient materials for thermoelectric generators and need further experimental and theoretical studies.

  4. Microstructure Analysis and Thermoelectric Properties of Melt-Spun Bi-Sb-Te Compounds

    Directory of Open Access Journals (Sweden)

    Weon Ho Shin

    2017-06-01

    Full Text Available In order to realize high-performance thermoelectric materials, a way to obtain small grain size is necessary for intensification of the phonon scattering. Here, we use a melt-spinning-spark plasma sintering process for making p-type Bi0.36Sb1.64Te3 thermoelectric materials and evaluate the relation between the process conditions and thermoelectric performance. We vary the Cu wheel rotation speed from 1000 rpm (~13 ms−1 to 4000 rpm (~52 ms−1 during the melt spinning process to change the cooling rate, allowing us to control the characteristic size of nanostructure in melt-spun Bi0.36Sb1.64Te3 ribbons. The higher wheel rotation speed decreases the size of nanostructure, but the grain sizes of sintered pellets are inversely proportional to the nanostructure size after the same sintering condition. As a result, the ZT values of the bulks fabricated from 1000–3000 rpm melt-spun ribbons are comparable each other, while the ZT value of the bulk from the 4000 rpm melt-spun ribbons is rather lower due to reduction of grain boundary phonon scattering. In this work, we can conclude that the smaller nanostructure in the melt spinning process does not always guarantee high-performance thermoelectric bulks, and an adequate following sintering process must be included.

  5. Electronic and Optical Properties of Ca3MN (M = Ge, Sn, Pb, P, As, Sb and Bi) Antiperovskite Compounds

    Science.gov (United States)

    Iqbal, Samad; Murtaza, G.; Khenata, R.; Mahmood, Asif; Yar, Abdullah; Muzammil, M.; Khan, Matiullah

    2016-08-01

    The electronic and optical properties of cubic antiperovskites Ca3MN (M = Ge, Sn, Pb, P, As, Sb and Bi) were investigated by applying the full potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) scheme based on density functional theory. Different exchange correlation potentials were adopted for the calculations. The results of band structure and density of states show that, by changing the central anion of Ca3MN, the nature of the materials change from metallic (Ca3GeN, Ca3SnN, Ca3PbN) to semiconducting with small band gaps (Ca3SbN and Ca3BiN) to insulating (Ca3PN and Ca3AsN). The optical properties such as dielectric function, absorption coefficient, optical conductivity, reflectivity and refractive indices have also been calculated. The results reveal that all the studied compounds are optically active in the visible and ultraviolet energy regions, and therefore can be effectively utilized for optoelectronic devices.

  6. First-principles study of XNMg{sub 3} (X = P, As, Sb and Bi) antiperovskite compounds

    Energy Technology Data Exchange (ETDEWEB)

    Amara, K., E-mail: kamaraphy@gmail.com [Laboratoire d’études Physiques et Chimiques, Université de Saida “Dr. Moulay Tahar”, Saida 20000 (Algeria); Zemouli, M.; Elkeurti, M. [Laboratoire d’études Physiques et Chimiques, Université de Saida “Dr. Moulay Tahar”, Saida 20000 (Algeria); Belfedal, A. [Laboratoire de Physique des Couches Minces et Matériaux pour l’Electronique, Université d’Oran Es-Sénia, Oran 31000 (Algeria); Saadaoui, F. [Laboratoire d’études Physiques et Chimiques, Université de Saida “Dr. Moulay Tahar”, Saida 20000 (Algeria)

    2013-11-05

    Highlights: •The investigated four nitrides XNMg{sub 3} (X = P, As, Sb and Bi) are mechanically stable. •AsNMg{sub 3} and PNMg{sub 3} have direct gaps, while SbNMg{sub 3} and BiNMg{sub 3} have indirect gaps. •The energy gaps using TB-mBJ are larger about 40–58% than that within GGA. •XNMg{sub 3} present mixed bonding: covalent-ionic. •Covalent nature of these materials increases when going from BiNMg{sub 3} to PNMg{sub 3}. -- Abstract: In this work, we present a study of the structural, elastic and electronic properties of the cubic antiperovskites XNMg{sub 3} (X = P, As, Sb and Bi) using the full-potential augmented plane wave plus local orbital (FP-LAPW + lo) within the generalized gradient approximation based on PBEsol, Perdew 2008 functional. We determined the lattice parameters, the bulk modulus B and their pressure derivative B′. In addition, the elastic properties such as elastic constants (C{sub 11}, C{sub 12} and C{sub 44}), the shear modulus G, the Young modulus E, the Poisson’s ratio ν and the B/G ratio are also given. For the band structure, density of states and charge density the exchange and correlation effects were treated by the Tran-Blaha modified Becke-Johnson potential to prevent the shortcoming of the underestimation of the energy gaps in both LDA and GGA approximations. The obtained results are compared to available experimental data and to other theoretical calculations.

  7. Structural and elastic properties under pressure effect of the cubic antiperovskite compounds ANCa{sub 3} (A = P, As, Sb, and Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Haddadi, K. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria)], E-mail: haddadi_khelifa@yahoo.fr; Bouhemadou, A.; Louail, L.; Maabed, S.; Maouche, D. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria)

    2009-04-27

    Using first-principles density functional calculations, the effect of high pressures, up to 40 GPa, on the structural and elastic properties of ANCa{sub 3}, with A = P, As, Sb, and Bi, were studied by means of the pseudo-potential plane-waves method. Calculations were performed within the local density approximation and the generalized gradient approximation for exchange-correlation effects. The lattice constants are in good agreement with the available results. The elastic constants and their pressure dependence are calculated using the static finite strain technique. We derived the bulk and shear moduli, Young's modulus, Poisson's ratio and Lame's constants for ideal polycrystalline ANCa{sub 3} aggregates. By analysing the ratio between the bulk and shear moduli, we conclude that ANCa{sub 3} compounds are brittle in nature. We estimated the Debye temperature of ANCa{sub 3} from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of PNCa{sub 3}, AsNCa{sub 3}, SbNCa{sub 3}, and BiNCa{sub 3} compounds, and it still awaits experimental confirmation.

  8. Reduction in thermal conductivity of BiSbTe lump

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Kaleem [King Saud University, Sustainable Energy Technologies Center, College of Engineering, PO Box 800, Riyadh (Saudi Arabia); Wan, C. [Tsinghua University, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Beijing (China); Al-Eshaikh, M.A.; Kadachi, A.N. [King Saud University, Research Center, College of Engineering, PO Box 800, Riyadh (Saudi Arabia)

    2017-03-15

    In this work, systematic investigations on the thermal conductivities of BiSbTe lump, microstructured pristine BiSbTe bulk and single wall carbon nanotubes (SWCNTs)/BiSbTe bulk nanocomposites were performed. BiSbTe lumps were crushed to form a coarse powder (200 μm) and effect of particle size reduction on the effective thermal conductivity of BiSbTe (200 μm) bulk were analyzed. For further reduction in the conductivity, a two pronged strategy has been employed. First, additional refinement of BiSbTe (200 μm) were performed through ball milling in an inert environment. Second, SWCNTs in 0.75, and 1.0 vol% were distributed uniformly in the fine BiSbTe ball milled powder. The results showed that the effective thermal conductivities decrease with the reduction in the particle size from lump to BiSbTe (200 μm) bulk as well as with the addition of SWCNTs accompanied by further refinement of BiSbTe particles. The significant reduction in thermal conductivities of the lump was achieved for pure BiSbTe (200 μm) bulk and 0.75 vol% of SWCNTs/BiSbTe composite. This can be ascribed to the enhanced phonon scattering by the grain boundaries between the nanostructured BiSbTe particles as well as the interfaces between BiSbTe and the low dimensional carbon nanotubes. (orig.)

  9. Lattice thermal transport in L a3C u3X4 compounds (X =P ,As ,Sb ,Bi ) : Interplay of anharmonicity and scattering phase space

    Science.gov (United States)

    Pandey, Tribhuwan; Polanco, Carlos A.; Lindsay, Lucas; Parker, David S.

    2017-06-01

    Thermal conductivities of L a3C u3X4 (X =P ,As ,Sb ,Bi ) compounds are examined using first-principles density functional theory and Boltzmann transport methods. We observe a trend of increasing lattice thermal conductivity (κl) with increasing atomic mass, challenging our expectations, as lighter mass systems typically have larger sound speeds and weaker intrinsic scattering. In particular, we find that L a3C u3P4 has the lowest κl, despite having larger sound speed and the most restricted available phase space for phonon-phonon scattering, an important criterion for estimating and comparing κl among like systems. The origin of this unusual behavior lies in the strength of the individual anharmonic phonon scattering matrix elements, which are much larger in L a3C u3P4 than in the heavier L a3C u3B i4 system. Our finding provides insights into the interplay of harmonic and anharmonic properties of complex, low-thermal-conductivity compounds, of potential use for thermoelectric and thermal barrier coating applications.

  10. Molecular beam epitaxy and characterization of high Bi content GaSbBi alloys

    Science.gov (United States)

    Delorme, O.; Cerutti, L.; Tournié, E.; Rodriguez, J.-B.

    2017-11-01

    The epitaxial growth, structural and optical properties of GaSb1-xBix layers are reported. The incorporation of Bi into GaSb is varied in the 0 spectroscopy. The surface morphology was observed by optical and atomic force microscopies. The samples show a smooth, droplet free surface up to 11.4% Bi incorporation. All samples exhibit room temperature PL up to a wavelength of 3.8 μm achieved for 14% Bi incorporation. Finally, these alloys have shown a great thermal stability after several annealing at 450 °C. This work thus presents the highest Bi-content GaSbBi alloys and the first demonstration of room-temperature PL emission from GaSbBi alloys.

  11. Photovoltaic applications of Cu(Sb,Bi)SM (M = Ag, Pb, Pt)

    Science.gov (United States)

    Tablero, C.

    2017-04-01

    Ternary Cu-(Sb,Bi)-S compounds are great absorbents of the solar radiation with a variety of applications including optoelectronic and photovoltaic applications. The analyses of several quaternary semiconductors derived from Cu-(Sb,Bi)-S materials is carried out using first-principles density-functional theory with orbital-dependent one-electron potentials. These analyses focus on the optoelectronic properties and the potential for solar cells. The optical properties are obtained from first-principles calculations, and split into inter- and intra-shell-species contributions in order to quantify the optical transitions responsible for the absorption. The absorption coefficients are then used as criteria to evaluate the efficiencies of these materials under several sunlight concentrations. The results indicate high energy photovoltaic conversion efficiency because of the large intra shell s-p absorption of the S and Sb or Bi atomic species.

  12. Lead activity in Pb-Sb-Bi alloys

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    A. S. Kholkina

    2014-11-01

    Full Text Available The present work is devoted to the study of lead thermodynamic activity in the Pb-Sb-Bi alloys. The method for EMF measurements of the concentration cell: (–Pb|KCl-PbCl2¦¦KCl-PbCl2|Pb-(Sb-Bi(+ was used. The obtained concentration dependences of the galvanic cell EMF are described by linear equations. The lead activity in the ternary liquid-metal alloy demonstrates insignificant negative deviations from the behavior of ideal solutions.

  13. Topological surface states on Bi$_{1-x}$Sb$_x$

    DEFF Research Database (Denmark)

    Zhu, Xie-Gang; Hofmann, Philip

    2014-01-01

    Topological insulators support metallic surface states whose existence is protected by the bulk band structure. It has been predicted early that the topology of the surface state Fermi contour should depend on several factors, such as the surface orientation and termination and this raises...... the question to what degree a given surface state is protected by the bulk electronic structure upon structural changes. Using tight-binding calculations, we explore this question for the prototypical topological insulator Bi$_{1-x}$Sb$_x$, studying different terminations of the (111) and (110) surfaces. We...

  14. Recovery of Bi and Sb from Copper Spent Electrolytes by Electrowinning Method.

    Science.gov (United States)

    Koo, Ja-Kyung; Hong, Heung-Ki; Lee, Jae-Ho

    2015-11-01

    The consumption of rare metals from the industrial development has been increasing despite of unstable and limited rare metals supply. Copper electrolyte after copper electrorefining contains 200-300 mg/L of bismuth (Bi) and antimony (Sb). Bi and Sb were recovered through electrowinning of electrochemical method. After being concentrated using an ion exchange resin method, Bi was eluted by concentrated sulfuric acid and sodium chloride solution. And then Bi deficient resin was reeluted by hydrochloric acid to elute Sb. Bi or Sb electrowinning cell was using the cation exchange membrane (CEM) to prevent migration of chloride ion to the anodic chamber. The morphologies of deposits were varied with current density and concentration. Over 95% purity of Bi and Sb were obtained by electrowinning method. The surface morphologies and compositions were analyzed by FESEM and EDS.

  15. Solid state compatibility in the ZnO-rich region of ZnO-Bi2O3-Sb2O3 and ZnO-Bi2O3-Sb2O5 systems

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    Jardiel, T.

    2010-04-01

    Full Text Available The obtaining of ZnO-Bi2O3-Sb2O3 (ZBS based varistor thick films with high non-linear properties is constrained by the bismuth loss by vaporization that takes place during the sintering step of these ceramics, a process which is yet more critical in the thick film geometry due to its inherent high are/volume ratio. This volatilization can be controlled to a certain extent by modifying the proportions of the Bi and/or Sb precursors. Obviously this requires a clear knowledge of the different solid state compatibilities in the mentioned ZBS system. In this sense a detailed study of the thermal evolution of the ZnO-Bi2O3-Sb2O3 and ZnO-Bi2O3-Sb2O5 systems in the ZnO-rich region of interest for varistors, is presented in this contribution. A different behaviour is observed when using Sb2O3 or Sb2O5 as starting precursor, which should be attributed to the oxidation process experimented by Sb2O3 compound during the heating. On the other hand the use of high amounts of Bi in the starting formulation leads to the formation of a liquid phase at lower temperatures, which would allow the use of lower sintering temperatures.La obtención de varistors en lámina gruesa basados en ZnO-Bi2O3-Sb2O3 (ZBS y con propiedades altamente no-lineales está limitada por la perdida de bismuto por volatilización durante la sinterización de estos cerámicos, un proceso que es todavía más crítico en la geometría de lámina gruesa debido a su elevada relación área/volumen inherente. Dicha volatilización puede ser no obstante controlada hasta cierta extensión modificando las proporciones de los precursores de Bi y/o Sb. Obviamente ello conlleva un amplio conocimiento de las diferentes compatibilidades en estado sólido en el mencionado sistema ZBS. En este sentido, en la presente contribución se presenta un estudio detallado de la evolución térmica de los sistemas ZnO-Bi2O3-Sb2O3 y ZnO-Bi2O3-Sb2O5 en la región rica en ZnO de interés para varistores. Como

  16. Emergence of topological and topological crystalline phases in TlBiS2 and TlSbS2

    KAUST Repository

    Zhang, Qingyun

    2015-02-11

    Using first-principles calculations, we investigate the band structure evolution and topological phase transitions in TlBiS2 and TlSbS2 under hydrostatic pressure as well as uniaxial and biaxial strain. The phase transitions are identified by parity analysis and by calculating the surface states. Zero, one, and four Dirac cones are found for the (111) surfaces of both TlBiS2 and TlSbS2 when the pressure grows, which confirms trivial-nontrivial-trivial phase transitions. The Dirac cones at the (M) over bar points are anisotropic with large out-of-plane component. TlBiS2 shows normal, topological, and topological crystalline insulator phases under hydrostatic pressure, thus being the first compound to exhibit a phase transition from a topological to a topological crystalline insulator.

  17. Solvothermal Synthesis of Ternary Sulfides of Sb2 − x Bi x S3(x = 0.4, 1 with 3D Flower-Like Architectures

    Directory of Open Access Journals (Sweden)

    Wang Guoxiu

    2009-01-01

    Full Text Available Abstract Flower-like nanostructures of Sb2 − x Bi x S3(x = 0.4, 1.0 were successfully prepared using both antimony diethyldithiocarbamate [Sb(DDTC3] and bismuth diethyldithiocarbamate [Bi(DDTC3] as precursors under solvothermal conditions at 180 °C. The prepared Sb2 − x Bi x S3 with flower-like 3D architectures were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, energy dispersive X-ray spectrometry (EDS, high-resolution transmission electron microscopy (HRTEM, and selected area electron diffraction (SAED. The flower-like architectures, with an average diameter of ~4 μm, were composed of single-crystalline nanorods with orthorhombic structures. The optical absorption properties of the Sb2 − x Bi x S3 nanostructures were investigated by UV–Visible spectroscopy, and the results indicate that the Sb2 − x Bi x S3 compounds are semiconducting with direct band gaps of 1.32 and 1.30 eV for x = 0.4 and 1.0, respectively. On the basis of the experimental results, a possible growth mechanism for the flower-like Sb2 − x Bi x S3 nanostructures is suggested.

  18. Crystalline structure, and magnetic and magneto-optical properties of MnSbBi thin films

    CERN Document Server

    Kang, K

    2001-01-01

    the c-axis texture and the saturation magnetisation due to less segregation of the non-magnetic phase in the annealed films. Using a thin Sb seed layer in Mn/Sb/Bi// films also results in an increase in both the c-axis texture and the saturation magnetisation. Decreasing the layer thicknesses in Mn/Bi/Sb// films results in a decrease in the grain size. By depositing the Sb layer first in Pt/Mn/Sb// and Co/Mn/Sb// films, the perpendicular c-axis texture can be kept before and after annealing. Computer simulation was carried out to investigate the relationship between the crystal structure and the magnetic properties before and after annealing. Comparing optical and MO properties of annealed Mn/Sb/Bi// and Mn/Sb// films suggests a possible origin of the peaks in Kerr spectra caused by adding Bi. This thesis reports work carried out to investigate some aspects of the crystal structure, and magnetic and magneto-optical (MO) properties in thin films of the Mn-Sb system. Reports of interesting properties and the po...

  19. Density functional study of BiSbTeSe{sub 2} topological insulator thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadpourrad, Zahra; Abolhassani, Mohammadreza [Department of Physics, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2017-08-15

    In this work, using density functional theory calculations, we have investigated the band topology of bulk BiSbTeSe{sub 2} and its thin film electronic properties in several thicknesses. It is one member of the quaternary compounds Bi{sub 2-x}Sb{sub x}Te{sub 3-y}Se{sub y} (BSTS) with the best intrinsic bulk insulating behavior. Based on our calculations we have found that a band inversion at Γ-point is induced when spin-orbit coupling is turned on, with an energy gap of about 0.318 eV. The film thickness has an effect on the surface states such that a gap opens at Dirac point in 6 quintuple-layers film and with decrease in thickness, the magnitude of the gap increases. The atomic contributions have been mapped out for the first few layers of thin films to demonstrate the surface states. The relative charge density has been calculated layer-wise and the penetration depth of the surface states into the bulk region is found to be about 2.5-3.5 quintuple layers, depending on the termination species of thin films. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Solvothermal synthesis and analysis of Bi{sub 1-x}Sb{sub x} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sumithra, S.; Misra, D.K.; Wei, C. [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Gabrisch, H. [GKSS Research Center, Institute of Materials Research, Geesthacht (Germany); Poudeu, P.F.P. [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States); Stokes, K.L., E-mail: klstokes@uno.edu [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States)

    2011-02-25

    Bismuth-antimony alloy nanoparticles have been synthesized by a facile solvothermal method using N,N-dimethylformamide and ethylene glycol as solvent/reducing agent; BiCl{sub 3}, SbCl{sub 3} and Bi(NO{sub 3}){sub 3} as precursors; and citric acid as a surface modifier/stabilizing agent. The particle size and size distribution of Bi nanoparticles were analyzed as a function of the synthesis conditions: molar ratio of precursor to surfactant, precursor concentration and reducing agent. Synthesis of Sb and Bi{sub 0.88}Sb{sub 0.12} under similar conditions was also investigated. The phase purity of nanoparticles was confirmed from X-ray diffraction and thermogravimetry and the nanoparticle morphology was investigated by transmission electron microscopy. A case study of Bi nanoparticles with detailed analysis of the particle morphology and size distribution of the nanoparticles is reported.

  1. Enhancement of power factor by energy filtering effect in hierarchical BiSbTe3 nanostructures for thermoelectric applications

    Science.gov (United States)

    Sabarinathan, M.; Omprakash, M.; Harish, S.; Navaneethan, M.; Archana, J.; Ponnusamy, S.; Ikeda, H.; Takeuchi, T.; Muthamizhchelvan, C.; Hayakawa, Y.

    2017-10-01

    The bismuth antimony telluride hierarchical nanostructures were synthesized by hydrothermal method using dodecanethiol as a capping agent. The flower like nanosheets with the length of 500-600 nm and thickness about 60-70 nm were obtained. XRD pattern confirmed that the formation of single phase BiSbTe3. The Raman spectroscopy measurement clearly revealed the vibration modes of BiSbTe3. The composition of synthesized compounds were homogeneous and it confirmed by energy dispersive X-ray spectroscopy (EDS). The maximum value of Seebeck coefficient and power factor were 171 μV/K and 74.78 μW/mK2, respectively for nanosheets which contains spherical shaped morphology at room temperature. The enhancement of Seebeck coefficient was due to energy dependent scattering of the charge carriers at the nanograin interfaces.

  2. Magnetic and structural properties of Bi(2223doped by pb and Sb

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    H. Salamati

    1998-04-01

    Full Text Available   In a systematic approach, we have investigated the effect of the presence of Pb and Sb in the Bi site in a BSCCO (2223 phase superconductor. There are some contradictory reports in substitution of Sb in the Bi site. Some researchers report an increase in the Tc of these materials. So, we have made an accurate stoichiometry of these superconductors and selected extra pure starting materials with appropriate ratios of Pb+Sb.   The susceptility of these samples have been measured and the structures of the systems have been studied by SEM and XRD. The results of this investigation show that, Although the presence of Pb is essential for formation of (2223 phase, but addition of small amount of Sb helps to stabilize and enhance the ratio of higher phase. Our results show that, presence of Sb would raise the critical current density, but would not affect the Tc of these superconductors.

  3. The Structural, Photocatalytic Property Characterization and Enhanced Photocatalytic Activities of Novel Photocatalysts Bi2GaSbO7 and Bi2InSbO7 during Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Jingfei Luan

    2016-09-01

    Full Text Available In order to develop original and efficient visible light response photocatalysts for degrading organic pollutants in wastewater, new photocatalysts Bi2GaSbO7 and Bi2InSbO7 were firstly synthesized by a solid-state reaction method and their chemical, physical and structural properties were characterized. Bi2GaSbO7 and Bi2InSbO7 were crystallized with a pyrochlore-type structure and the lattice parameter of Bi2GaSbO7 or Bi2InSbO7 was 10.356497 Å or 10.666031 Å. The band gap of Bi2GaSbO7 or Bi2InSbO7 was estimated to be 2.59 eV or 2.54 eV. Compared with nitrogen doped TiO2, Bi2GaSbO7 and Bi2InSbO7, both showed excellent photocatalytic activities for degrading methylene blue during visible light irradiation due to their narrower band gaps and higher crystallization perfection. Bi2GaSbO7 showed higher catalytic activity compared with Bi2InSbO7. The photocatalytic degradation of methylene blue followed by the first-order reaction kinetics and the first-order rate constant was 0.01470 min−1, 0.00967 min−1 or 0.00259 min−1 with Bi2GaSbO7, Bi2InSbO7 or nitrogen doped TiO2 as a catalyst. The evolution of CO2 and the removal of total organic carbon were successfully measured and these results indicated continuous mineralization of methylene blue during the photocatalytic process. The possible degradation scheme and pathway of methylene blue was also analyzed. Bi2GaSbO7 and Bi2InSbO7 photocatalysts both had great potential to purify textile industry wastewater.

  4. The Structural, Photocatalytic Property Characterization and Enhanced Photocatalytic Activities of Novel Photocatalysts Bi2GaSbO7 and Bi2InSbO7 during Visible Light Irradiation

    Science.gov (United States)

    Luan, Jingfei; Shen, Yue; Li, Yanyan; Paz, Yaron

    2016-01-01

    In order to develop original and efficient visible light response photocatalysts for degrading organic pollutants in wastewater, new photocatalysts Bi2GaSbO7 and Bi2InSbO7 were firstly synthesized by a solid-state reaction method and their chemical, physical and structural properties were characterized. Bi2GaSbO7 and Bi2InSbO7 were crystallized with a pyrochlore-type structure and the lattice parameter of Bi2GaSbO7 or Bi2InSbO7 was 10.356497 Å or 10.666031 Å. The band gap of Bi2GaSbO7 or Bi2InSbO7 was estimated to be 2.59 eV or 2.54 eV. Compared with nitrogen doped TiO2, Bi2GaSbO7 and Bi2InSbO7, both showed excellent photocatalytic activities for degrading methylene blue during visible light irradiation due to their narrower band gaps and higher crystallization perfection. Bi2GaSbO7 showed higher catalytic activity compared with Bi2InSbO7. The photocatalytic degradation of methylene blue followed by the first-order reaction kinetics and the first-order rate constant was 0.01470 min−1, 0.00967 min−1 or 0.00259 min−1 with Bi2GaSbO7, Bi2InSbO7 or nitrogen doped TiO2 as a catalyst. The evolution of CO2 and the removal of total organic carbon were successfully measured and these results indicated continuous mineralization of methylene blue during the photocatalytic process. The possible degradation scheme and pathway of methylene blue was also analyzed. Bi2GaSbO7 and Bi2InSbO7 photocatalysts both had great potential to purify textile industry wastewater. PMID:28773922

  5. First-principles simulation on thermoelectric properties in Bi-Sb System

    Science.gov (United States)

    El-Asfoury, M. S.; Nakamura, K.; Abdel-Moneim, A.

    2017-12-01

    Thermoelectric properties of bismuth-antimony (Bi-Sb) alloy system were simulated on the basis of first-principles calculation, to discuss the potential for thermoelectric devices. Atomistic model structures of Bi-Sb alloy system were devised in the forms of single-crystal bulk and one-dimensional nanowire under the periodic boundary condition. The cell parameters of the bulk model were simulated with respect to temperature by the quasi-harmonic approximation through phonon calculation, and dependences of the Seebeck coefficient on composition, surface condition, and temperature have been demonstrated by using our original methodology in terms of the electronic state of Bi-Sb alloy system. For the single-crystal bulk Bi-Sb models, a meaningful effect of the composition on the Seebeck coefficient has not been observed, whereas a clear difference in phonon dispersion was confirmed between pure Bi and Sb-substituted Bi, leading to the significant difference in thermal conductivity. We clarified that the surface condition is a key point to control the Seebeck coefficient for the nanowire form.

  6. Thermodynamic analysis and characterization of alloys in Bi-Cu-Sb system

    Directory of Open Access Journals (Sweden)

    Živković D.

    2010-01-01

    Full Text Available The results of thermodynamic analysis and characterization of some alloys in Bi-Cu-Sb lead-free solder system are presented in this paper. Thermodynamic analysis was done using general solution model, while optic microscopy, hardness and electroconductivity measurements were used in order to determine structural, mechanic and electric characteristics of selected samples in section from bismuth corner with molar ratio Cu:Sb=3:7.

  7. Lattice Distortion in In3SbTe2 Phase Change Material with Substitutional Bi.

    Science.gov (United States)

    Choi, Minho; Choi, Heechae; Kim, Seungchul; Ahn, Jinho; Kim, Yong Tae

    2015-08-11

    Sb atoms in In3SbTe2 (IST) are partially substituted by 3.2-5.5 at.% of Bi atoms. As a result, the NaCl crystal structure of IST is slightly distorted. The distorted inter-planar angles observed with fast Fourier transformation of the lattice images are within the maximum range of interplanar angles calculated by density functional theory. When the Bi content is increased, the crystallization temperature becomes relatively lower than that of IST, the activation energy decreases from 5.29 to 2.61 eV, and the specific heat and melting point are obviously reduced. Consequently, phase change random access memory (PRAM) fabricated with Bi-doped IST (Bi-IST) can operate with lower power consumption than pure IST PRAM. The set and reset speeds of PRAM cells fabricated with Bi-IST are both 100 ns with 5.5 at.% Bi, which are obviously faster than the switching speeds of PRAM cells fabricated with IST and Ge2Sb2Te5 (GST). These experimental results reveal that the switching speed is closely related with the thermal properties of the distorted lattice structure.

  8. Fabrication and characterization of the -type (Bi 2 Te 3) (Sb 2 Te ...

    Indian Academy of Sciences (India)

    In the present study, -type (Bi2Te3)(Sb2Te3)1– crystals with various chemical compositions ( = 0.2, 0.22, 0.235, 0.25, 0.265, 0.28 and 0.3) were fabricated through the zone melting method. Thermoelectric properties, including Seebeck coefficient (), electrical conductivity (), thermal conductivity () and Hall ...

  9. Investigations on MnSb and related compounds with b8-type structures

    NARCIS (Netherlands)

    Bouwma, Jakob

    1972-01-01

    This thesis describes investigations on phases with hexagonal B8-type structures in the systems Mn-Sb-Sn, Mn-Sb-Te, Mn-Cr-Sb and Mn-V-Sb. In -chapter 1 some general remarks are made on compounds with B8-type structures. The preparation of the samples, and the X-ray crystallographic investigations

  10. Molecular beam epitaxy growth of InSb1-xBix thin films

    DEFF Research Database (Denmark)

    Yuxin Song; Shumin Wang; Saha Roy, Ivy

    2013-01-01

    Molecular beam epitaxy growth for InSb1-xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology...

  11. Synthesis, Characterization and Photocatalytic Activity of New Photocatalyst ZnBiSbO4 under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Jingfei Luan

    2014-05-01

    Full Text Available In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2 and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC wastewater was detected by examining its effect on seed germination and growth.

  12. Synthesis, Characterization and Photocatalytic Activity of New Photocatalyst ZnBiSbO4 under Visible Light Irradiation

    Science.gov (United States)

    Luan, Jingfei; Chen, Mengjing; Hu, Wenhua

    2014-01-01

    In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. PMID:24879521

  13. The motley family of polar compounds (MV)[M(X{sub 5-x}X Prime {sub x})] based on anionic chains of trans-connected M{sup (III)}(X,X Prime ){sub 6} octahedra (M=Bi, Sb; X, X Prime =Cl, Br, I) and methylviologen (MV) dications

    Energy Technology Data Exchange (ETDEWEB)

    Leblanc, Nicolas [Laboratoire MOLTECH-Anjou, UMR-CNRS 6200, Universite d' Angers 2 Bd Lavoisier, 49045 Angers (France); Mercier, Nicolas, E-mail: nicolas.mercier@univ-angers.fr [Laboratoire MOLTECH-Anjou, UMR-CNRS 6200, Universite d' Angers 2 Bd Lavoisier, 49045 Angers (France); Allain, Magali; Toma, Oksana [Laboratoire MOLTECH-Anjou, UMR-CNRS 6200, Universite d' Angers 2 Bd Lavoisier, 49045 Angers (France); Auban-Senzier, Pascale; Pasquier, Claude [Laboratoire de Physique des Solides, UMR-CNRS 8502, Bat. 510,Universite Paris Sud, 91405 Orsay (France)

    2012-11-15

    The search for hybrid organic-inorganic materials remains a great challenge in the field of ferroelectrics. Following the discovery of the room temperature ferroelectric material (MV)[BiI{sub 3}Cl{sub 2}] (MV{sup 2+}: methylviologen) exhibiting the highest polarization value in the field of hybrid ferroelectrics, we report here nine new hybrids with the general formulation (MV)[M{sup (III)}X{sub 5-x}X Prime {sub x}] (M=Bi, Sb; X, X Prime =Cl, Br, I): (MV)[BiCl{sub 3.3}Br{sub 1.7}] (1), (MV)[BiCl{sub 1.3}Br{sub 3.7}] (2), (MV)[BiBr{sub 3.2}I{sub 1.8}] (3), (MV)[SbCl{sub 5}] (4), (MV)[SbBr{sub 5}] (5), (MV)[SbCl{sub 3.8}Br{sub 1.2}] (6), (MV)[SbCl{sub 2.4}Br{sub 2.6}] (7), (MV)[SbI{sub 3}Cl{sub 2}] (8) and (MV)[SbBr{sub 3.8}I{sub 1.2}] (9). Depending on the presence of polar chains or not, and on the coupling of polar chains, two types of centrosymmetrical structures [C1] and [C2] and two types of polar structures [P1] and [P2] are defined. (2) undergoes a paraelectric-to-relaxor ferroelectric transition around 100-150 K depending of the frequency showing that the Curie temperature, T{sub C}, of (MV)[BiBr{sub 5}] (243 K) can be modulated by the substitution of Br by Cl. The most interesting family is the [P2] type because the syn coupling of polar chains is in favor of high polarization values, as in (MV)[BiI{sub 3}Cl{sub 2}]. Five of the nine new hybrids, (4), (6-9), which have the [P2] type structure are potential ferroelectrics. - Graphical abstract: The methylviologen haloantimonate (MV)[SbX{sub 5-x}X Prime {sub x}] families (X, X Prime =Cl, Br, I) - [P1] and [P2] are the two kinds of polar structures - and view of the (MV)[SbBr{sub 3.8}I{sub 1.2}] hybrid based on chiral polar chains which are in syn coupling. Highlights: Black-Right-Pointing-Pointer Nine hybrids based on methylviologen and halometalate chains have been discovered. Black-Right-Pointing-Pointer The polar nature of chains is due to the ns{sup 2} stereoactivity of Sb{sup (III)} or Bi{sup (III

  14. Temperature dependence of ferromagnetic resonance spectra of permalloy on (Bi1‑ x Sb x )2Te3

    Science.gov (United States)

    Gupta, Sachin; Kanai, Shun; Matsukura, Fumihiro; Ohno, Hideo

    2018-02-01

    We investigate the temperature dependence of ferromagnetic resonance spectra of permalloy (Py: Ni0.80Fe0.20) on (Bi1‑ x Sb x )2Te3 with x = 0–1. Smaller resonance fields and broader linewidths are observed for Py/(Bi,Sb)2Te3 than those for Py/substrate below ∼40 K. The result indicates the presence of the coupling as well as spin pumping at the interface between Py and (Bi,Sb)2Te3.

  15. Optical probing of ultrafast electronic decay in Bi and Sb with slow phonons.

    Science.gov (United States)

    Li, J J; Chen, J; Reis, D A; Fahy, S; Merlin, R

    2013-01-25

    Illumination with laser sources leads to the creation of excited electronic states of particular symmetries, which can drive isosymmetric vibrations. Here, we use a combination of ultrafast stimulated and cw spontaneous Raman scattering to determine the lifetime of A(1g) and E(g) electronic coherences in Bi and Sb. Our results both shed new light on the mechanisms of coherent phonon generation and represent a novel way to probe extremely fast electron decoherence rates. The E(g) state, resulting from an unequal distribution of carriers in three equivalent band regions, is extremely short lived. Consistent with theory, the lifetime of its associated driving force reaches values as small as 2 (6) fs for Bi (Sb) at 300 K.

  16. Temperature and impurity effect on parallel field magnetoconductance of bulk insulating topological insulator (Bi1‑x Sb x )2Te3

    Science.gov (United States)

    Urkude, R. R.; Rawat, R.; Palikundwar, U. A.

    2017-12-01

    We have performed a systematic parallel field magnetotransport studies of (Bi1‑x Sb x )2Te3 to understand the temperature and impurity effect on the interference of bulk conductance on the surface states of highly insulating topologically insulating compound Bi2Te3. The compound exhibits a weak antilocalization effect (WAL) at low temperature and low magnetic field. WAL weakens and a weak localization effect is observed to be developed in the compound with the increase in temperature due to the creation of topologically trivial 2D electron gas states. Strong interlayer interference and coupling of bulk carriers with surface states are observed at low temperature. A similar temperature effect is observed for all concentrations of Sb. Topologically protected surface states enhance with the increase in Sb contents up to x  =  0.3 however, a further increase in Sb concentration leads to a decrease in surface states. The data has been analysed via the generalised Altshuler and Aronov model for parallel field transport anticipating weak antilocalization and interlayer interference.

  17. MEMS/ECD Method for Making Bi(2-x)Sb(x)Te3 Thermoelectric Devices

    Science.gov (United States)

    Lim, James; Huang, Chen-Kuo; Ryan, Margaret; Snyder, G. Jeffrey; Herman, Jennifer; Fleurial, Jean-Pierre

    2008-01-01

    A method of fabricating Bi(2-x)Sb(x)Te3-based thermoelectric microdevices involves a combination of (1) techniques used previously in the fabrication of integrated circuits and of microelectromechanical systems (MEMS) and (2) a relatively inexpensive MEMS-oriented electrochemical-deposition (ECD) technique. The present method overcomes the limitations of prior MEMS fabrication techniques and makes it possible to satisfy requirements.

  18. In-plane heterostructures of Sb/Bi with high carrier mobility

    Science.gov (United States)

    Zhao, Pei; Wei, Wei; Sun, Qilong; Yu, Lin; Huang, Baibiao; Dai, Ying

    2017-06-01

    In-plane two-dimensional (2D) heterostructures have been attracting public attention due to their distinctive properties. However, the pristine materials that can form in-plane heterostructures are reported only for graphene, hexagonal BN, transition-metal dichalcogenides. It will be of great significance to explore more suitable 2D materials for constructing such ingenious heterostructures. Here, we demonstrate two types of novel seamless in-plane heterostructures combined by pristine Sb and Bi monolayers by means of first-principle approach based on density functional theory. Our results indicate that external strain can serve as an effective strategy for bandgap engineering, and the transition from semiconductor to metal occurs when a compressive strain of -8% is applied. In addition, the designed heterostructures possess direct band gaps with high carrier mobility (˜4000 cm2 V-1 s-1). And the mobility of electrons and holes have huge disparity along the direction perpendicular to the interface of Sb/Bi in-plane heterostructures. It is favorable for carriers to separate spatially. Finally, we find that the band edge positions of Sb/Bi in-plane heterostructures can meet the reduction potential of hydrogen generation in photocatalysis. Our results not only offer alternative materials to construct versatile in-plane heterostructures, but also highlight the applications of 2D in-plane heterostructures in diverse nanodevices and photocatalysis.

  19. Synthesis and Evaluation of Thick Films of Electrochemically Deposited Bi2Te3 and Sb2Te3 Thermoelectric Materials

    Science.gov (United States)

    Trung, Nguyen Huu; Sakamoto, Kei; Toan, Nguyen Van; Ono, Takahito

    2017-01-01

    This paper presents the results of the synthesis and evaluation of thick thermoelectric films that may be used for such applications as thermoelectric power generators. Two types of electrochemical deposition methods, constant and pulsed deposition with improved techniques for both N-type bismuth telluride (Bi2Te3) and P-type antimony telluride (Sb2Te3), are performed and compared. As a result, highly oriented Bi2Te3 and Sb2Te3 thick films with a bulk-like structure are successfully synthesized with high Seebeck coefficients and low electrical resistivities. Six hundred-micrometer-thick Bi2Te3 and 500-µm-thick Sb2Te3 films are obtained. The Seebeck coefficients for the Bi2Te3 and Sb2Te3 films are −150 ± 20 and 170 ± 20 µV/K, respectively. Additionally, the electrical resistivity for the Bi2Te3 is 15 ± 5 µΩm and is 25 ± 5 µΩm for the Sb2Te3. The power factors of each thermoelectric material can reach 15 × 10−4 W/mK2 for Bi2Te3 and 11.2 × 10−4 W/mK2 for Sb2Te3. PMID:28772511

  20. Synthesis and Evaluation of Thick Films of Electrochemically Deposited Bi2Te3 and Sb2Te3 Thermoelectric Materials

    Directory of Open Access Journals (Sweden)

    Nguyen Huu Trung

    2017-02-01

    Full Text Available This paper presents the results of the synthesis and evaluation of thick thermoelectric films that may be used for such applications as thermoelectric power generators. Two types of electrochemical deposition methods, constant and pulsed deposition with improved techniques for both N-type bismuth telluride (Bi2Te3 and P-type antimony telluride (Sb2Te3, are performed and compared. As a result, highly oriented Bi2Te3 and Sb2Te3 thick films with a bulk-like structure are successfully synthesized with high Seebeck coefficients and low electrical resistivities. Six hundred-micrometer-thick Bi2Te3 and 500-µm-thick Sb2Te3 films are obtained. The Seebeck coefficients for the Bi2Te3 and Sb2Te3 films are −150 ± 20 and 170 ± 20 µV/K, respectively. Additionally, the electrical resistivity for the Bi2Te3 is 15 ± 5 µΩm and is 25 ± 5 µΩm for the Sb2Te3. The power factors of each thermoelectric material can reach 15 × 10−4 W/mK2 for Bi2Te3 and 11.2 × 10−4 W/mK2 for Sb2Te3.

  1. Bi-sulphotellurides associated with Pb - Bi - (Sb ± Ag, Cu, Fe) sulphosalts: an example from the Stan Terg deposit in Kosovo

    Science.gov (United States)

    Kołodziejczyk, Joanna; Pršek, Jaroslav; Voudouris, Panagiotis Ch.; Melfos, Vasilios

    2017-08-01

    New mineralogical and mineral-chemical data from the Stan Terg deposit, Kosovo, revealed the presence of abundant Bi-sulphotellurides associated with Bi- and Sb-sulphosalts and galena in pyrite-pyrrhotite-rich skarn-free ore bodies (ores without skarn minerals). The Bi-bearing association comprises Bi-sulphotellurides (joséite-A, joséite-B, unnamed phase A with a chemical formula close to (Bi,Pb)2(TeS)2, unnamed phase B with a chemical composition close to (Bi,Pb)2.5Te1.5S1.5), ikunolite, cosalite, Sb-lillianite, members of the kobellite series and Bi-jamesonite. Compositional trends of the Bi-sulphotellurides suggest lattice-scale incorporation of Bi-(Pb)-rich module and/or admixture with submicroscopic PbS layers in modulated structures, or complicated Bi-Te substitution. Cosalite is characterized by high Sb (max. 3.94 apfu), and low Cu and Ag (up to 0.72 apfu of Cu+Ag). Jamesonite from this mineralization has elevated Bi content, from 0.85 to 2.30 apfu. The negligible content of Au and Ag in the Bi-sulphotellurides, the low content of Ag in Bi-sulphosalts, together with the lack of Au-Ag bearing phases in the mineralization, indicate either ore deposition from fluid(s) depleted in precious metals, or physico-chemical conditions of ore formation preventing Au and Ag precipitation at the deposit site. The temperature of initial mineralization may have exceeded 400 °C as suggested by the lamellar exsolution textures observed in lillianite, which indicate breakdown textures from decomposition of high-temperature initial crystals. Non-stoichiometric phases among the Bi-sulphosalts and sulphotellurides studied at Stan Terg reflect modulated growth processes in a metasomatic environment.

  2. Photoemission study of the skutterudite compounds CoSb sub 3 and RhSb sub 3

    CERN Document Server

    Ishii, H; Fujimori, A; Nagamoto, Y; Koyanagi, T; Sofo, J O

    2002-01-01

    We have studied the electronic structure of the skutterudite compounds CoSb sub 3 and Co(Sb sub 0 sub . sub 9 sub 6 Te sub 0 sub . sub 0 sub 4) sub 3 by photoemission spectroscopy. Valence-band spectra revealed that a significant amount Sb 5p states are present near the Fermi level and are hybridized with Co 3d states just below it. The spectra are well reproduced by the band-structure calculation, suggesting that the effect of electron correlations is not important. When Te is substituted for Sb and n-type carriers are doped into CoSb sub 3 , the spectra are shifted to higher binding energies as described by the rigid-band model. From this shift and the free-electron model for the conduction and valence bands, we have estimated the band gap of CoSb sub 3 to be 0.03-0.04 eV, consistent with transport measurements. Photoemission spectra of RhSb sub 3 have also been measured and revealed expected similarities to and differences from those of CoSb sub 3. Unusual temperature dependence has been observed for the s...

  3. MISFIT LAYER COMPOUNDS BASED ON DOUBLE-LAYERS MX AND SANDWICHES TX2 (M=SN, PB, SB, BI, LN - T=TI, V, CR, NB, TA - X=S, SE)

    NARCIS (Netherlands)

    WIEGERS, GA

    1993-01-01

    Misfit layer compounds have a composite structure with two interpenetrating subsystems, an MX and an TX2 or (TX2)2 subsystem. Several structure types occur, the main difference coming from the different type of coordination of transition metal T by X atoms of the TX2 sandwiches. All structures show

  4. Enhanced stability of Bi-doped Ge2Sb2Te5 amorphous films

    Science.gov (United States)

    Dyussembayev, S.; Prikhodko, O.; Tsendin, K.; Timoshenkov, S.; Korobova, N.

    2014-09-01

    Although, several reviews have appeared on various physical properties and applications of chalcogenide glasses, there is no thorough study of local atomic structure and its modification for eutectic Ge-Sb-Te alloys doped with Bi. Ge2Sb2Te5 pure and Bi-doped films were deposited by ion-plasma sputtering method of synthesized GTS material on Si (100) and glass substrates coated with a conductive Al layer which was used as a bottom electrode. Current-voltage characteristics of different points of the same samples have been measured. Random distribution of inclusions within the sample made it possible to investigate the dependence of switching and memory effects on the phase composition at a constant value of other parameters. Measurements in the current controlled mode clearly showed that the memory state formation voltage does not depend on current in a wide range. Results indicate that the development of imaging technologies phase memory cells need to pay special attention to the conditions of Ge-Sb-Te film preparation. To increase the number of cycles "write - erase" should be additional prolonged annealing of the synthesized films.

  5. Crystallographic study of the intermediate compounds SbZn, Sb{sub 3}Zn{sub 4} and Sb{sub 2}Zn{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Adjadj, Fouzia [Laboratoire des etudes Physico-chimiques des Materiaux, Departement de Physique, Faculte des Sciences, Universite de Batna, 05000 Batna (Algeria); Belbacha, El-djemai [Laboratoire des etudes Physico-chimiques des Materiaux, Departement de Physique, Faculte des Sciences, Universite de Batna, 05000 Batna (Algeria)]. E-mail: Beldjem@caramail.com; Bouharkat, Malek [Laboratoire des etudes Physico-chimiques des Materiaux, Departement de Physique, Faculte des Sciences, Universite de Batna, 05000 Batna (Algeria); Kerboub, Abdellah [Laboratoire des etudes Physico-chimiques des Materiaux, Departement de Physique, Faculte des Sciences, Universite de Batna, 05000 Batna (Algeria)

    2006-08-10

    The processes of development of semiconductor ceramics made up of bismuth, antimony and zinc often require during their preparation to know the nature of the involved phases. For that, it is always essential to refer to the diagrams of balance between phases of the binary systems or ternary. We presented in this work the study by X-rays diffraction relating to the intermediate compounds SbZn, Sb{sub 3}Zn{sub 4} and Sb{sub 2}Zn{sub 3}. The analysis by X-rays is often useful to give supplement the results of the other experimental methods.

  6. Electronic structures of Si- and Te-doped CoSb3 compounds under high pressures

    Science.gov (United States)

    Kobayashi, Kazuaki; Ullah Khan, Atta; Mori, Takao

    2017-05-01

    The electronic and lattice properties of various Si- and Te-doped CoSb3 compounds under hydrostatic compression conditions were calculated by using the total energy pseudopotential method. The calculated compositions of Si- and Te-doped CoSb3 compounds are Co8Sb22Si2, Co8Sb22Te2, Co8Sb21Si2Te1, and Co8Sb21Si1Te2. The applied pressure P values are 0 (ambient), 10, and 100 GPa. The densities of states (DOSs) of Si- and Te-doped CoSb3 compounds under P = 0, 10, and 100 GPa are investigated to compare them with each other. Their DOS shapes and Fermi level positions vary under pressure. In particular, the variations in DOS shape between P = 10 and 100 GPa in Co8Sb21Si2Te1 and Co8Sb21Si1Te2 are markedly large, although they are relatively small between P = 0 and 10 GPa. The gap states of Co8Sb21Si2Te1 and Co8Sb21Si1Te2 around the Fermi level disappear under P = 100 GPa. Seebeck coefficients do not increase under high pressures.

  7. ZT enhancement in solution-grown Sb(2-x)Bi(x)Te3 nanoplatelets

    OpenAIRE

    Scheele, Marcus; Oeschler, Niels; Veremchuk, Igor; Reinsberg, Klaus-Georg; Kreuziger, Anna-Marlena; Kornowski, Andreas; Broekaert, Jose; Klinke, Christian; Weller, Horst

    2011-01-01

    We report a solution-processed, ligand supported synthesis of 15-20 nm thick Sb(2-x)Bi(x)Te3 nanoplatelets. After complete ligand removal by a facile NH3-based etching procedure, the platelets are spark plasma sintered to a p-type nanostructured bulk material with preserved crystal grain sizes. Due to this nanostructure, the total thermal conductivity is reduced by 60 % in combination with a reduction in electric conductivity of as low as 20 % as compared to the bulk material demonstrating th...

  8. Growth and characterization of MnGa thin films with perpendicular magnetic anisotropy on BiSb topological insulator

    Science.gov (United States)

    Duy Khang, Nguyen Huynh; Ueda, Yugo; Yao, Kenichiro; Hai, Pham Nam

    2017-10-01

    We report on the crystal growth as well as the structural and magnetic properties of Bi0.8Sb0.2 topological insulator (TI)/MnxGa1-x bi-layers grown on GaAs(111)A substrates by molecular beam epitaxy. By optimizing the growth conditions and Mn composition, we were able to grow MnxGa1-x thin films on Bi0.8Sb0.2 with the crystallographic orientation of Bi0.8Sb0.2(001)[1 1 ¯ 0]//MnGa (001)[100]. Using magnetic circular dichroism (MCD) spectroscopy, we detected both the L10 phase ( x 0.6 ) of MnxGa1-x. For 0.50 ≤ x ≤ 0.55 , we obtained ferromagnetic L10-MnGa thin films with clear perpendicular magnetic anisotropy, which were confirmed by MCD hysteresis, anomalous Hall effect as well as superconducting quantum interference device measurements. Our results show that the BiSb/MnxGa1-x bi-layer system is promising for perpendicular magnetization switching using the giant spin Hall effect in TIs.

  9. Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A 3 M 2 I 9 (A = Cs, Rb; M = Bi, Sb)

    Energy Technology Data Exchange (ETDEWEB)

    McCall, Kyle M.; Stoumpos, Constantinos C.; Kostina, Svetlana S.; Kanatzidis, Mercouri G.; Wessels, Bruce W.

    2017-04-26

    The optical and electronic properties of Bridgman grown single crystals of the wide-bandgap semiconducting defect halide perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb) have been investigated. Intense Raman scattering was observed at room temperature for each compound, indicating high polarizability and strong electron–phonon coupling. Both low-temperature and room-temperature photoluminescence (PL) were measured for each compound. Cs3Sb2I9 and Rb3Sb2I9 have broad PL emission bands between 1.75 and 2.05 eV with peaks at 1.96 and 1.92 eV, respectively. The Cs3Bi2I9 PL spectra showed broad emission consisting of several overlapping bands in the 1.65–2.2 eV range. Evidence of strong electron–phonon coupling comparable to that of the alkali halides was observed in phonon broadening of the PL emission. Effective phonon energies obtained from temperature-dependent PL measurements were in agreement with the Raman peak energies. A model is proposed whereby electron–phonon interactions in Cs3Sb2I9, Rb3Sb2I9, and Cs3Bi2I9 induce small polarons, resulting in trapping of excitons by the lattice. The recombination of these self-trapped excitons is responsible for the broad PL emission. Rb3Bi2I9, Rb3Sb2I9, and Cs3Bi2I9 exhibit high resistivity and photoconductivity response under laser photoexcitation, indicating that these compounds possess potential as semiconductor hard radiation detector materials.

  10. Thermoelectric properties of Bi0.5Sb1.5Te3 thin films grown by pulsed laser deposition

    Science.gov (United States)

    Symeou, E.; Pervolaraki, M.; Mihailescu, C. N.; Athanasopoulos, G. I.; Papageorgiou, Ch.; Kyratsi, Th.; Giapintzakis, J.

    2015-05-01

    We report on the pulsed laser deposition of p-type Bi0.5Sb1.5Te3 thin films onto fused silica substrates by ablation of dense targets of Bi0.5Sb1.5Te3 with an excess of 1 wt% Te. We investigated the effect of film thickness, substrate temperature and post-annealing duration on the thermoelectric properties of the films. Our results show that the best power factor (2780 μW/K2m at 300 K) is obtained for films grown at room temperature and then post-annealed in vacuum at 300 °C for 16 h. This is among the highest power factor values reported for Bi0.5Sb1.5Te3 films grown on fused silica substrates.

  11. Mott theory predicted thermoelectric properties based on electronic structure of Bi and Sb atoms substituted PbTe material

    Science.gov (United States)

    Vora-ud, Athorn

    2017-11-01

    In this work, thermoelectric properties of Bi and Sb atoms substituted PbTe material were predicted by Mott theory through electronic structure calculation. This calculation has been carried by the first-principles DV-Xα molecular orbital method based on Hartree-Fock-Slater approximation. The Pb14Te13, Pb13SbTe13 and Pb13BiTe13 small clusters with a cubic rocksalt structure (Fm-3m; 225) were designed to be performed PbTe, Pb0.75Sb0.25Te and Pb0.75Bi0.25Te materials, respectively. The electronic structure showed that the high symmetry crystal structure, spin energy levels, partial spin density of states and electron charge density. The energy gap and Fermi level have been obtained from energy levels and density of state to be evaluated of electrical conductivity and Seebeck coefficient within Mott's theory predication.

  12. Anisotropic magnetoresistance in topological insulator Bi1.5Sb0.5Te1.8Se1.2/CoFe heterostructures

    National Research Council Canada - National Science Library

    Xia, B; Ren, P; Sulaev, Azat; Li, Z. P; Liu, P; Dong, Z. L; Wang, L

    2012-01-01

    ... Bi1.5Sb0.5Te1.8Se1.2/CoFe heterostructures. To explain the novel effect, we propose that the Bi1.5Sb0.5Te1.8Se1.2/CoFe heterostructure forms a spin-valve or Giant magnetoresistance device due to spin-momentum locking...

  13. Electronic structure of InTe, SnAs and PbSb: Valence-skip compound or not?

    Energy Technology Data Exchange (ETDEWEB)

    Hase, Izumi, E-mail: i.hase@aist.go.jp [National Institute of Advanced Industrial Science and Technology, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba 305-8568 (Japan); Yasutomi, Kouki [Graduate School of Pure and Applied Science, Univ. of Tsukuba, Tsukuba, 305-8571 (Japan); Yanagisawa, Takashi; Odagiri, Kousuke [National Institute of Advanced Industrial Science and Technology, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba 305-8568 (Japan); Nishio, Taichiro [Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601 (Japan)

    2016-08-15

    Highlights: • We calculated the electronic structure of InTe, SnAs and PbSb from first principles. • Obtained tight-binding parameters of InTe are close to those of BaBiO3, which suggests that their electronic properties are also alike. • InTe is favorable to emerge valence skip, while PbSb is not favorable for it. SnAs is between the two. • Our findings well agree with the experimental results. - Abstract: InTe, SnAs and PbSb formally have unusual valence states, In{sup 2+}, Sn{sup 3+} and Pb{sup 3+}. All of them have B1 crystal structure at some pressure range. They are candidates of the valence-skip compound, which may have negative effective Coulomb interaction U{sub eff} < 0. Negative-U Hubbard model is known to show charge-density wave or superconductivity in some parameter region. In fact, SnAs becomes superconducting at ambient pressure. InTe has a kind of charge-density wave at ambient pressure, and it becomes superconducting at high pressure. We investigated their electronic structures by ab-initio calculations, and calculated the number of s-electrons at the cation site. We found that InTe is favorable to emerge valence skip, while PbSb is not favorable for valence skip. SnAs is between these two. These findings well agree with the experimental results.

  14. Study of the influence of semiconductor material parameters on acoustic wave propagation modes in GaSb/AlSb bi-layered structures by Legendre polynomial method

    Energy Technology Data Exchange (ETDEWEB)

    Othmani, Cherif, E-mail: othmanicheriffss@gmail.com; Takali, Farid; Njeh, Anouar; Ben Ghozlen, Mohamed Hédi

    2016-09-01

    The propagation of Rayleigh–Lamb waves in bi-layered structures is studied. For this purpose, an extension of the Legendre polynomial (LP) method is proposed to formulate the acoustic wave equation in the bi-layered structures induced by thin film Gallium Antimonide (GaSb) and with Aluminum Antimonide (AlSb) substrate in moderate thickness. Acoustic modes propagating along a bi-layer plate are shown to be quite different than classical Lamb modes, contrary to most of the multilayered structures. The validation of the LP method is illustrated by a comparison between the associated numerical results and those obtained using the ordinary differential equation (ODE) method. The convergency of the LP method is discussed through a numerical example. Moreover, the influences of thin film GaSb parameters on the characteristics Rayleigh–Lamb waves propagation has been studied in detail. Finally, the advantages of the Legendre polynomial (LP) method to analyze the multilayered structures are described. All the developments performed in this work were implemented in Matlab software.

  15. Experimental preparation of lateral Heterojunction Sb2Te3/Bi2Te3 Nanoplates

    Science.gov (United States)

    Fei, Fucong; Song, Fengqi

    For the first time, lateral heterojunction of Sb2Te3-Bi2Te3 was successfully realized using a two-step solvothermal method. The two crystalline components were separated well by a sharp lattice-matched interface when the optimized procedure was used. Inspecting the heterojunction using high-resolution transmission electron microscopy showed that epitaxial growth occurred along the horizontal plane. The semiconducting temperature-resistance curve and crossjunction rectification were observed, which reveal a staggered-gap lateral heterojunction with a small junction voltage. Quantum correction from the weak antilocalization reveals the well-maintained transport of the topological surface state. This is appealing for a platform for spin filters and one-dimensional topological interface states. The relevant works on materials optimization and fabrication of spin devices are already under way. (Nanoletters 2015, 15, 5905 -5911))

  16. Investigations on organoantimony compounds II. Preparation and configuration of organo(oxinato)antimony(V) compounds RnSbCl4−nOx (n = 1−4)

    NARCIS (Netherlands)

    Meinema, H.A.; Rivarola, E.; Noltes, J.G.

    Organo(oxinato)antimony(V) compounds of the types RSbCl3Ox, R2SbCl2Ox, R3SbClOx and R4SbOx (R = alkyl and phenyl) have been synthesized and and investigated by spectroscopic (UV, PMR, IR) methods. All the compounds are monomeric in benzene. In all the compounds except R3SbClOx (R = alkyl), which

  17. Fe-Doping Effect on Thermoelectric Properties of p-Type Bi0.48Sb1.52Te3

    Directory of Open Access Journals (Sweden)

    Hyeona Mun

    2015-03-01

    Full Text Available The substitutional doping approach has been shown to be an effective strategy to improve ZT of Bi2Te3-based thermoelectric raw materials. We herein report the Fe-doping effects on electronic and thermal transport properties of polycrystalline bulks of p-type Bi0.48Sb1.52Te3. After a small amount of Fe-doping on Bi/Sb-sites, the power factor could be enhanced due to the optimization of carrier concentration. Additionally, lattice thermal conductivity was reduced by the intensified point-defect phonon scattering originating from the mass difference between the host atoms (Bi/Sb and dopants (Fe. An enhanced ZT of 1.09 at 300 K was obtained in 1.0 at% Fe-doped Bi0.48Sb1.52Te3 by these synergetic effects.

  18. Extremely Large Magnetoresistance in Bi0.96Sb0.04

    Science.gov (United States)

    Sudesh, Sudesh; Kumar, Pawan; Patnaik, Satyabrata

    Recent experimental evidence for Weyl fermions in topological semimetals has attracted considerable attention. These materials are three-dimensional analogue of graphene. The present work is motivated by the recent prediction of Weyl semi-metallic phase in Bi1-xSbx alloys. In this paper we present the electronic transport properties studied under high applied magnetic fields in Bi0.96Sb0.04 alloys. The sample exhibits extremely high magneto-resistance; MR(5 K, 8 T) = 9.8×104 %. This value is comparable to the MR observed in recently discovered other members of these emergent materials. Most importantly, this composition shows large MR at room temperature, MR (300 K, 8 T) = 435%, which is almost twice to that observed in Dirac semimetal Cd3As2 (= 200 % at 14.5 T) and Weyl semimetal NbP (= 250% at 9 T). We also discuss single crystal growth techniques as well as Hall and Shubnikov de Haas (SdH) oscillation data. References We acknowledge the DIST-FIST supported low temperature-high magnetic field facility at JNU and AIRF, JNU for the access of experimental facilities to carry out this study. Sudesh and P. Kumar thank UGC, (Government of India) for financial support.

  19. Theoretical prediction of thermodynamic activities of liquid Au-Sn-X (X=Bi, Sb, Zn) solder systems

    Energy Technology Data Exchange (ETDEWEB)

    Awe, O.E., E-mail: draweoe2004@yahoo.com [Department of Physics, University of Ibadan, Ibadan (Nigeria); Department of Physics and Engineering Physics, Obafemi Awolowo University, Ile-Ife (Nigeria); Oshakuade, O.M. [Department of Physics, University of Ibadan, Ibadan (Nigeria)

    2017-02-15

    Molecular interaction volume model has been theoretically used to predict the thermodynamic activities of tin in Au-Sn-Bi and Au-Sn-Sb and the thermodynamic activity of zinc in Au-Sn-Zn at experimental temperatures 800 K, 873 K and 973 K, respectively. On the premise of agreement between the predicted and experimental values, we predicted the activities of the remaining two components in each of the three systems. This prediction was extended from three cross-sections to five cross-sections, and to temperature range 400–600 K, relevant for applications. Iso-activities were plotted. Results show that addition of tin reduces the tendency for chemical short range order in both Au-Sb and Au-Zn systems, while addition of gold and bismuth, respectively, reduce the tendency for chemical short range order in Sn-Sb and Au-Sn systems. Also, we found that, in the desired high-temperature region for applications, while a combination of chemical order and miscibility of components exist in both Au-Sn-Bi and Au-Sn-Zn systems, only chemical order exist in the Au-Sn-Sb system. Results, further show that increase in temperature reduces the phase separation tendency in Au-Sn-Bi system.

  20. Potential 2D thermoelectric material ATeI (A = Sb and Bi) monolayers from a first-principles study

    Science.gov (United States)

    Guo, San-Dong; Zhang, Ai-Xia; Li, Hui-Chao

    2017-11-01

    Lots of two-dimensional (2D) materials have been predicted theoretically and further confirmed in experiments, and have wide applications in nanoscale electronic, optoelectronic and thermoelectric devices. In this work, the thermoelectric properties of ATeI (A = Sb and Bi) monolayers are systematically investigated according to semiclassical Boltzmann transport theory. It is found that spin-orbit coupling (SOC) has an important effect on the electronic transport coefficients of p-type doping, but a negative influence on n-type doping. The room-temperature sheet thermal conductance is 14.2 {{W}} {{{K}}}-1 for SbTeI and 12.6 {{W}} {{{K}}}-1 for BiTeI, which is lower than that of most well-known 2D materials, such as the transition-metal dichalcogenide, group IV-VI, group VA and group IV monolayers. The very low sheet thermal conductance of ATeI (A = Sb and Bi) monolayers is mainly due to their small group velocities and short phonon lifetimes. The strongly polarized covalent bonds between A and Te or I atoms induce strong phonon anharmonicity, which gives rise to low lattice thermal conductivity. It is found that the high-frequency optical branches contribute significantly to the total thermal conductivity, which is obviously different from the usual picture, where there is little contribution from the optical branches. According to cumulative lattice thermal conductivity with respect to the phonon mean free path (MFP), it is difficult to further reduce the lattice thermal conductivity using nanostructures. Finally, the possible thermoelectric figure of merit ZT values of the ATeI (A = Sb and Bi) monolayers are calculated. It is found that p-type doping has much better thermoelectric properties than n-type doping. At room temperature, the peak ZT can reach 1.11 for SbTeI and 0.87 for BiTeI, respectively. These results make us believe that ATeI (A = Sb and Bi) monolayers may be potential 2D thermoelectric materials, which could stimulate further experimental work

  1. Evolution of thermoelectric performance for (Bi,Sb)2Te3 alloys from cutting waste powders to bulks with high figure of merit

    Science.gov (United States)

    Fan, Xi‧an; Cai, Xin zhi; Han, Xue wu; Zhang, Cheng cheng; Rong, Zhen zhou; Yang, Fan; Li, Guang qiang

    2016-01-01

    Bi2Te3 based cutting waste powders from cutting wafers were firstly selected as raw materials to prepare p-type Bi2Te3 based thermoelectric (TE) materials. Through washing, reducing, composition correction, smelting and resistance pressing sintering (RPS) process, p-type (Bi,Sb)2Te3 alloy bulks with different nominal stoichiometries were successfully obtained. The evolution of microstructure and TE performance for (Bi,Sb)2Te3 alloys were investigated in detail. All evidences confirmed that most of contaminants from line cutting process such as cutting fluid and oxides of Bi, Sb or Te could be removed by washing, reducing and smelting process used in this work. The carrier content and corresponding TE properties could be adjusted effectively by appropriate composition correction treatment. At lastly, a bulk with a nominal stoichiometry of Bi0.44Sb1.56Te3 was obtained and its' dimensionless figure of merit (ZT) was about 1.16 at 90 °C. The ZT values of Bi0.36Sb1.64Te3 and Bi0.4Sb1.6Te3 alloy bulks could also reach 0.98 and 1.08, respectively. Different from the conventional recycling technology such as hydrometallurgy extraction methods, the separation and extraction of beneficial elements such as Bi, Sb and Te did not need to be performed and the Bi2Te3 based bulks with high TE properties could be directly obtained from the cutting waste powders. In addition, the recycling technology introduced here was green and more suitable for practical industrial application. It can improve material utilization and lower raw material costs of manufacturers.

  2. Triple Bonds Between Iron and Heavier Group 15 Elements in AFe(CO)3-(A=As, Sb, Bi) Complexes.

    Science.gov (United States)

    Wang, Jia-Qi; Chi, Chaoxian; Hu, Han-Shi; Meng, Luyan; Luo, Mingbiao; Li, Jun; Zhou, Mingfei

    2018-01-08

    Heteronuclear transition-metal-main-group-element carbonyl complexes of AsFe(CO) 3 - , SbFe(CO) 3 - , and BiFe(CO) 3 - were produced by a laser vaporization supersonic ion source in the gas phase, and were studied by mass-selected IR photodissociation spectroscopy and advanced quantum chemistry methods. These complexes have C 3v structures with all of the carbonyl ligands bonded on the iron center, and feature covalent triple bonds between bare Group 15 elements and Fe(CO) 3 - . Chemical bonding analyses on the whole series of AFe(CO) 3 - (A=N, P, As, Sb, Bi, Mc) complexes indicate that the valence orbitals involved in the triple bonds are hybridized 3d and 4p atomic orbitals of iron, leading to an unusual (dp-p) type of transition-metal-main-group-element multiple bonding. The σ-type three-orbital interaction between Fe 3d/4p and Group 15 np valence orbitals plays an important role in the bonding and stability of the heavier AFe(CO) 3 - (A=As, Sb, Bi) complexes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Effect of Ga2O3 Nanoparticles Dispersion on Microstructure and Thermoelectric Properties of p-Type BiSbTe Based Alloys

    Directory of Open Access Journals (Sweden)

    Kim E.-B.

    2017-06-01

    Full Text Available In this study, p-type Bi0.5Sb1.5Te3 based nanocomposites with addition of different weight percentages of Ga2O3 nanoparticles are fabricated by mechanical milling and spark plasma sintering. The fracture surfaces of all Bi0.5Sb1.5Te3 nanocomposites exhibited similar grain distribution on the entire fracture surface. The Vickers hardness is improved for the Bi0.5Sb1.5Te3 nanocomposites with 6 wt% added Ga2O3 due to exhibiting fine microstructure, and dispersion strengthening mechanism. The Seebeck coefficient of Bi0.5Sb1.5Te3 nanocomposites are significantly improved owing to the decrease in carrier concentration. The electrical conductivity is decreased rapidly upon the addition of Ga2O3 nanoparticle due to increasing carrier scattering at newly formed interfaces. The peak power factor of 3.24 W/mK2 is achieved for the base Bi0.5Sb1.5Te3 sintered bulk. The Bi0.5Sb1.5Te3 nanocomposites show low power factor than base sample due to low electrical conductivity.

  4. [Spectral study of two Bi (III) contained heteropolymate compounds].

    Science.gov (United States)

    Wang, Yong-Jing; Zhang, Han-Hui; Huang, Chang-Cang; Chen, Yi-Ping; Sun, Rui-Qing

    2006-02-01

    Two Bi (III) contained heteropolymate compounds Cos [Bi2 Co2 W20 O70 (H2O)6] x 44H2O (I)and Na3 H2 [Ce3 (H2O)18 Bi2 W22 O76] x 23H2O (II) have been synthesized under hydrothermal condition. The relationship between their properties and structures was studied by using FTIR, NIR FT-Raman, and UV-Vis DRS etc. The characteristic vibrational frequencies nu(as) (M = O(d)) and nu(s) (M-O(b)-M) is related to the structure of the materials. Nu(as) (M-O(b)-M) is demonstrated to explain why the the oxidative ability becomes stronger when W atoms are substituted by Co atoms. In UV-Vis DRS spectra of compound I and II, there are two characteristic peaks at 254, 319 nm and 220, 310 nm coresponding O(d) --> W and to O(b), c --> W charge transfer, respectively. The wide and weak absorption band of compound I at 529 nm can be assigned as Co2+ d-d transfer. Finally, quantum chemistry calculation of compound I was performed to explain the structure characteristic.

  5. Effect of the spin-orbit interaction on the thermodynamic properties of Bi and Sb

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, Reinhard K.; Cardona, Manuel [Max-Planck-Institut fuer Festkoerperforschung, D-70569 Stuttgart (Germany); Diaz-Sanchez, Luis E.; Romero, Aldo H. [CINVESTAV, Departamento de Materiales, Unidad Queretaro, Queretaro, 76230 (Mexico); Gonze, Xavier [Unite de Physico-Chimie et de Physique des Materiaux Universite Catholique de Louvain B-1348 Louvain-la-Neuve (Belgium); Serrrano, Jorge [ICREA-Dept. Fisica Aplicada, EPSC, Universitat Politecnica de Catalunya, Av. Canal Olimpic 15, 08860 Castelldefels (Spain)

    2009-07-01

    In the past years we have carried out a series of experiments as well as ab initio calculations of the dependence of the specific heat of semiconductors and insulators on T and isotopic masses. First results on the binary lead chalcogenides revealed marked differences between the calculated and the experimental heat capacities and the phonon dispersion relations. This finding raised the question of whether these discrepancies were due to the lack of spin-orbit (s-o) coupling in the ab initio electronic structure calculations. Using the ABINIT code which was recently extended to include s-o interaction we calculated the dispersion relations and the specific heat and compare it with our new low-temperature heat capacity measurements on Bi, Sb and PbX (X=S,Se,Te) and existing experimentally determined phonon dispersion relations. We find that agreement between measurements and calculations significantly improves when s-o interaction is included. Differences for the various investigated elements and binary systems are discussed.

  6. Evolution of thermoelectric performance for (Bi,Sb){sub 2}Te{sub 3} alloys from cutting waste powders to bulks with high figure of merit

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xi' an, E-mail: groupfxa@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China); School of Materials and Metallurgy, Wuhan University of Science and Technology, 947 Heping Road, Qingshan District, Wuhan 430081 (China); Cai, Xin zhi, E-mail: xzcwust@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China); School of Materials and Metallurgy, Wuhan University of Science and Technology, 947 Heping Road, Qingshan District, Wuhan 430081 (China); Han, Xue wu, E-mail: hanxuewu1990@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China); School of Materials and Metallurgy, Wuhan University of Science and Technology, 947 Heping Road, Qingshan District, Wuhan 430081 (China); Zhang, Cheng cheng, E-mail: zcc516990418@live.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China); School of Materials and Metallurgy, Wuhan University of Science and Technology, 947 Heping Road, Qingshan District, Wuhan 430081 (China); and others

    2016-01-15

    Bi{sub 2}Te{sub 3} based cutting waste powders from cutting wafers were firstly selected as raw materials to prepare p-type Bi{sub 2}Te{sub 3} based thermoelectric (TE) materials. Through washing, reducing, composition correction, smelting and resistance pressing sintering (RPS) process, p-type (Bi,Sb){sub 2}Te{sub 3} alloy bulks with different nominal stoichiometries were successfully obtained. The evolution of microstructure and TE performance for (Bi,Sb){sub 2}Te{sub 3} alloys were investigated in detail. All evidences confirmed that most of contaminants from line cutting process such as cutting fluid and oxides of Bi, Sb or Te could be removed by washing, reducing and smelting process used in this work. The carrier content and corresponding TE properties could be adjusted effectively by appropriate composition correction treatment. At lastly, a bulk with a nominal stoichiometry of Bi{sub 0.44}Sb{sub 1.56}Te{sub 3} was obtained and its' dimensionless figure of merit (ZT) was about 1.16 at 90 °C. The ZT values of Bi{sub 0.36}Sb{sub 1.64}Te{sub 3} and Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} alloy bulks could also reach 0.98 and 1.08, respectively. Different from the conventional recycling technology such as hydrometallurgy extraction methods, the separation and extraction of beneficial elements such as Bi, Sb and Te did not need to be performed and the Bi{sub 2}Te{sub 3} based bulks with high TE properties could be directly obtained from the cutting waste powders. In addition, the recycling technology introduced here was green and more suitable for practical industrial application. It can improve material utilization and lower raw material costs of manufacturers. - Graphical abstract: Three kinds of typical morphologies for the fractographs: typical lamellar structure, agglomerated submicron-sized granules and dispersed cubic particles from the initial cutting waste powders. - Highlights: • Bi{sub 2}Te{sub 3} based wastes were directly selected as raw materials

  7. Microstructures and thermoelectric properties of GeSbTe based layered compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yan, F.; Zhu, T.J.; Zhao, X.B. [Zhejiang University, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Hangzhou (China); Dong, S.R. [Zhejiang University, Department of Information and Electronics Engineering, Hangzhou (China)

    2007-08-15

    Microstructures and thermoelectric properties of Ge{sub 1}Sb{sub 2}Te{sub 4} and Ge{sub 2}Sb{sub 2}Te{sub 5} chalcogenide semiconductors have been investigated to explore the possibility of their thermoelectric applications. The phase transformation from the face-centered cubic to hexagonal structure was observed in Ge{sub 2}Sb{sub 2}Te{sub 5} compounds prepared by the melt spinning technique. The Seebeck coefficient and electrical resistivity of the alloys were increased due to the enhanced scattering of charge carriers at grain boundaries. The maximum power factors of the rapidly solidified Ge{sub 1}Sb{sub 2}Te{sub 4} and Ge{sub 2}Sb{sub 2}Te{sub 5} attained 0.975 x 10{sup -3} Wm{sup -1}K{sup -2} at 750 K and 0.767 x 10{sup -3} Wm{sup -1}K{sup -2} at 643 K respectively, higher than those of water quenched counterparts, implying that thermoelectric properties of GeSbTe based layered compounds can be improved by grain refinement. The present results show this class of chalcogenide semiconductors is promising for thermoelectric applications. (orig.)

  8. Synthesis and Thermoelectric Properties of Ni-Doped ZrCoSb Half-Heusler Compounds

    Directory of Open Access Journals (Sweden)

    Degang Zhao

    2018-01-01

    Full Text Available The Ni-doped ZrCo1−xNixSb half-Heusler compounds were prepared by arc-melting and spark plasma sintering technology. X-ray diffraction analysis results showed that all samples were crystallized in a half-Heusler phase. Thermoelectric properties of ZrCo1−xNixSb compounds were measured from room temperature to 850 K. The electrical conductivity and the absolute value of Seebeck coefficient increased with the Ni-doping content increasing due to the Ni substitution at Co. sites. The lattice thermal conductivity of ZrCo1−xNixSb samples was depressed dramatically because of the acoustic phonon scattering and point defect scattering. The figure of merit of ZrCo1−xNixSb compounds was improved due to the decreased thermal conductivity and improved power factor. The maximum ZT value of 0.24 was achieved for ZrCo0.92Ni0.08Sb sample at 850 K.

  9. Electrodeposition of textured Bi{sub 27}Sb{sub 28}Te{sub 45} nanowires with enhanced electrical conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Maksudul, E-mail: maksudul.hasan@tyndall.ie [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Gautam, Devendraprakash [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Enright, Ryan [Thermal Management Research Group, Efficient Energy Transfer Department, Bell Labs Ireland, Alcatel-Lucent Ireland Ltd., Dublin (Ireland)

    2016-04-15

    This work presents the template based pulsed potential electrodeposition technique of highly textured single crystalline bismuth antimony telluride (Bi{sub 1-x}Sb{sub x}){sub 2}Te{sub 3} nanowires from a single aqueous electrolyte. Cyclic voltammetry was used as an electroanalytical tool to assess the effect of the precursor concentrations on the composition of the deposits and to determine the deposition potential for each element. Pulsed potential electrodeposition was then applied on a gold-coated anodised alumina template to examine the effect of the pulse parameters on the composition and texture of Bi{sub 27}Sb{sub 28}Te{sub 45} nanowires. The nanowires are cylindrical in shape formed during the deposition inside the porous template and highly textured as they are decorated with sparse distribution of small crystal domains. The electrical conductivity (24.1 × 10{sup 4} S m{sup −1}) of a single nanowire was measured using a four-point probe technique implemented on a custom fabricated test chip. In this work, we demonstrated that crystal orientation with respect to the transport direction controlled by tuning the pulsed electrodeposition parameters. This allowed us to realise electrical conductivities ∼2.5 times larger than Sb doped bismuth-tellurium based ternary material systems and similar to what is typically seen in binary systems. - Highlights: • Pulsed electrodeposition is described towards fabrication of (Bi{sub 1-x}Sb{sub x}){sub 2}Te{sub 3} nanowires. • The adopted method is compatible with existing CMOS process. • The nanowires were fabricated as highly textured to enhance phonon scattering. • The electrical conductivity is ∼2.5 times larger than the current ternary materials.

  10. Crystal structure of (Bi0.94Sb1.06)S3 and reconsideration of cation distribution over mixed sites in the bismuthinitestibnite solid-solution series

    DEFF Research Database (Denmark)

    Poleti, Dejan; Karanović, Ljiljana; Balic Zunic, Tonci

    2012-01-01

    The intermediate member of the (Bi,Sb)(2)S-3 solid-solution series was prepared by dry synthesis at low temperature (200 degrees C) with a long annealing period in sealed silica tube. The EDS analysis yielded an empirical formula (Bi0.96Sb1.04)S-3, which is very close to the formula (Bi0.94Sb1.06...

  11. Exotic topological insulator states and topological phase transitions in Sb2Se3-Bi2Se3 heterostructures

    KAUST Repository

    Zhang, Qianfan

    2012-03-27

    Topological insulator is a new state of matter attracting tremendous interest due to its gapless linear dispersion and spin momentum locking topological states located near the surface. Heterostructures, which have traditionally been powerful in controlling the electronic properties of semiconductor devices, are interesting for topological insulators. Here, we studied the spatial distribution of the topological state in Sb 2Se 3-Bi 2Se 3 heterostructures by first-principle simulation and discovered that an exotic topological state exists. Surprisingly, the state migrates from the nontrivial Bi 2Se 3 into the trivial Sb 2Se 3 region and spreads across the entire Sb 2Se 3 slab, extending beyond the concept of "surface" state while preserving all of the topological surface state characteristics. This unusual topological state arises from the coupling between different materials and the modification of electronic structure near Fermi energy. Our study demonstrates that heterostructures can open up opportunities for controlling the real-space distribution of the topological state and inducing quantum phase transitions between topologically trivial and nontrivial states. © 2012 American Chemical Society.

  12. Carrier-mediated ferromagnetism in the magnetic topological insulator Cr-doped (Sb,Bi)2Te3

    Science.gov (United States)

    Ye, Mao; Li, Wei; Zhu, Siyuan; Takeda, Yukiharu; Saitoh, Yuji; Wang, Jiajia; Pan, Hong; Nurmamat, Munisa; Sumida, Kazuki; Ji, Fuhao; Liu, Zhen; Yang, Haifeng; Liu, Zhengtai; Shen, Dawei; Kimura, Akio; Qiao, Shan; Xie, Xiaoming

    2015-01-01

    Magnetically doped topological insulators, possessing an energy gap created at the Dirac point through time-reversal-symmetry breaking, are predicted to exhibit exotic phenomena including the quantized anomalous Hall effect and a dissipationless transport, which facilitate the development of low-power-consumption devices using electron spins. Although several candidates of magnetically doped topological insulators were demonstrated to show long-range magnetic order, the realization of the quantized anomalous Hall effect is so far restricted to the Cr-doped (Sb,Bi)2Te3 system at extremely low temperature; however, the microscopic origin of its ferromagnetism is poorly understood. Here we present an element-resolved study for Cr-doped (Sb,Bi)2Te3 using X-ray magnetic circular dichroism to unambiguously show that the long-range magnetic order is mediated by the p-hole carriers of the host lattice, and the interaction between the Sb(Te) p and Cr d states is crucial. Our results are important for material engineering in realizing the quantized anomalous Hall effect at higher temperatures. PMID:26582485

  13. Structural and Thermoelectric Properties of Bi85Sb15 Prepared by Non-equal Channel Angular Extrusion

    Science.gov (United States)

    El-Asfoury, Mohamed S.; Nasr, Mohamed N. A.; Nakamura, Koichi; Abdel-Moneim, Ahmed

    2018-01-01

    We report on the mechanical and transport properties of polycrystalline bulk Bi85Sb15, as a low-temperature thermoelectric material. Bi85Sb15 samples were prepared by mechanical alloying and hot isostatic pressing, followed by sever plastic deformation (SPD). SPD was applied by either equal channel angular extrusion (ECAE) or non-equal channel angular extrusion (NECAE), at two different temperatures (373 K and 423 K). X-ray diffraction and scanning electron microscopy were used to characterize the prepared samples. The transport properties including the electrical conductivity, Seebeck coefficient and thermal conductivity were investigated, and correlated with the microstructure over the temperature range of 160-360 K. NECAE was found to be more effective than ECAE in enhancing bulk density, grain refinement and preferential grain orientation along the extrusion direction, particularly at higher processing temperatures. This is attributed to the better grain alignment and the creation of more intense grain boundaries and dislocation density, which resulted in an enhancement in carrier mobility and phonon scattering and hence a higher Z value. The highest Z value was achieved via NECAE at 423 K, and had a value of 0.39 × 10-3 K-1 at 250 K, which is 55% higher than that of the hot-pressed sample, 0.22 × 10-3 K-1 at 270 K. Also, the micro-hardness of the hot-pressed sample increases by at least 20% by SPD processes. Accordingly, optimized SPD can be classified as an effective processing tool for feasible mass production of bulk Bi85Sb15 alloy with better thermoelectric performance.

  14. Structural and Thermoelectric Properties of Bi85Sb15 Prepared by Non-equal Channel Angular Extrusion

    Science.gov (United States)

    El-Asfoury, Mohamed S.; Nasr, Mohamed N. A.; Nakamura, Koichi; Abdel-Moneim, Ahmed

    2017-09-01

    We report on the mechanical and transport properties of polycrystalline bulk Bi85Sb15, as a low-temperature thermoelectric material. Bi85Sb15 samples were prepared by mechanical alloying and hot isostatic pressing, followed by sever plastic deformation (SPD). SPD was applied by either equal channel angular extrusion (ECAE) or non-equal channel angular extrusion (NECAE), at two different temperatures (373 K and 423 K). X-ray diffraction and scanning electron microscopy were used to characterize the prepared samples. The transport properties including the electrical conductivity, Seebeck coefficient and thermal conductivity were investigated, and correlated with the microstructure over the temperature range of 160-360 K. NECAE was found to be more effective than ECAE in enhancing bulk density, grain refinement and preferential grain orientation along the extrusion direction, particularly at higher processing temperatures. This is attributed to the better grain alignment and the creation of more intense grain boundaries and dislocation density, which resulted in an enhancement in carrier mobility and phonon scattering and hence a higher Z value. The highest Z value was achieved via NECAE at 423 K, and had a value of 0.39 × 10-3 K-1 at 250 K, which is 55% higher than that of the hot-pressed sample, 0.22 × 10-3 K-1 at 270 K. Also, the micro-hardness of the hot-pressed sample increases by at least 20% by SPD processes. Accordingly, optimized SPD can be classified as an effective processing tool for feasible mass production of bulk Bi85Sb15 alloy with better thermoelectric performance.

  15. Quantum spin Hall effect and topological phase transition in InN x Bi y Sb1-x-y /InSb quantum wells

    Science.gov (United States)

    Song, Zhigang; Bose, Sumanta; Fan, Weijun; Zhang, Dao Hua; Zhang, Yan Yang; Shen Li, Shu

    2017-07-01

    Quantum spin Hall (QSH) effect, a fundamentally new quantum state of matter and topological phase transitions are characteristics of a kind of electronic material, popularly referred to as topological insulators (TIs). TIs are similar to ordinary insulator in terms of their bulk bandgap, but have gapless conducting edge-states that are topologically protected. These edge-states are facilitated by the time-reversal symmetry and they are robust against nonmagnetic impurity scattering. Recently, the quest for new materials exhibiting non-trivial topological state of matter has been of great research interest, as TIs find applications in new electronics and spintronics and quantum-computing devices. Here, we propose and demonstrate as a proof-of-concept that QSH effect and topological phase transitions can be realized in {{InN}}x{{Bi}}y{{Sb}}1-x-y/InSb semiconductor quantum wells (QWs). The simultaneous incorporation of nitrogen and bismuth in InSb is instrumental in lowering the bandgap, while inducing opposite kinds of strain to attain a near-lattice-matching conducive for lattice growth. Phase diagram for bandgap shows that as we increase the QW thickness, at a critical thickness, the electronic bandstructure switches from a normal to an inverted type. We confirm that such transition are topological phase transitions between a traditional insulator and a TI exhibiting QSH effect—by demonstrating the topologically protected edge-states using the bandstructure, edge-localized distribution of the wavefunctions and edge-state spin-momentum locking phenomenon, presence of non-zero conductance in spite of the Fermi energy lying in the bandgap window, crossover points of Landau levels in the zero-mode indicating topological band inversion in the absence of any magnetic field and presence of large Rashba spin-splitting, which is essential for spin-manipulation in TIs.

  16. Separation studies of As(III), Sb(III) and Bi(III) by reversed-phase paper chromatographic technique

    Energy Technology Data Exchange (ETDEWEB)

    Raman, B.; Shinde, V.M.

    1987-07-01

    Reversed-phase paper chromatographic separations of As(III), Sb(III) and Bi(III) have been carried out on Whatman No 1 filter paper impregnated with triphenylphosphine oxide as stationary phase and using organic complexing agents such as sodium acetate, sodium succinate and sodium malonate solutions as active mobile phases. Results for the separation of binary and ternary mixtures are reported and the method has been successfully applied to the separation and detection of these elements present in real samples and at ppm level concentration.

  17. Thermoelectric behaviour of (Bi 0.5Sb 0.5) 2Te 3 semiconducting alloy thin films

    Science.gov (United States)

    Damodara Das, V.; Chandra Mallik, Ramesh

    2001-10-01

    The Jain-Verma theory has been applied to the thermoelectric data of vacuum flash-evaporated and annealed polycrystalline thin films of (Bi 0.5Sb 0.5) 2Te 3 alloys of different thicknesses to study the nature of principal carrier scattering mechanism and also to know the extent of other scattering mechanisms, simultaneously. It is found that the value of the energy dependent scattering index parameter lies between -0.45 and -0.4. This indicates that, even though the principal scattering mechanism in the films is the normal lattice scattering, other scattering like 'impurity' scattering, surface scattering and grain boundary scattering may be present.

  18. Crystal structure of Ba2(La0.727Ba0.182M0.091)MO6 (M = Nb, Sb, Bi): symmetry nuance identified in photoluminescence and IR spectroscopy studies.

    Science.gov (United States)

    Phatak, Rohan; Gupta, Santosh K; Maheshwari, Priya; Das, Amitabh; Sali, Sanjay K

    2017-01-31

    A one-third lanthanum deficiency was created in Ba2LaM(5+)O6 compounds (LaM compounds) to form Ba2La2/3M(5+)O5.5 compounds (La2/3M compounds) for M = Nb, Sb, and Bi. The compounds were prepared by a gel-combustion method using citric acid as a fuel. All the compounds were characterized by powder X-ray diffraction (XRD). The XRD analysis showed that the space group of the La2/3M compounds remains the same for the Bi and Sb samples when compared to the reported LaM compounds, except for the Nb sample. La2/3Nb and La2/3Sb adopt a rhombohedral structure with the space group R3[combining macron], whereas La2/3Bi adopts a monoclinic structure with the space group I2/m. As the positron annihilation spectroscopy (PALS) technique is sensitive to cation deficiency, it was used to detect the presence of cation vacancies in the samples, which are formed due to the decrease in the lanthanum concentration. The PALS analyses indicated that the absence of cation deficiency in the La2/3M compounds is similar to that observed in the LaM compound. Thus, the crystal structure of the La2/3M compound was modeled, such that the cation deficiency at the La site is filled by Ba(2+) and M(5+) ions, and the crystal structure formula is given as Ba2(La0.727Ba0.182M0.091)MO6. This model was confirmed by Rietveld refinement of the XRD data. The emission spectra of Eu(3+) showed a strong dependence on its local site symmetry in the host material, in which it is being doped and this can be used as a spectroscopic probe for detecting any differences in the symmetry. Comparison of the local symmetry around La(3+) cation was studied using photoluminescence (PL) by doping 2 atom% Eu(3+) in LaM and La2/3M compounds. Infrared spectroscopy (IRS) analyses were also carried out for LaM and La2/3M compounds. There was complete agreement between the PL and IRS results and they were also in concordance with the predicted crystal structure model. Interestingly in these La2/3M compounds, the equilibrium

  19. Spin-polarized quasi-one-dimensional state with finite band gap on the Bi/InSb(001) surface

    Science.gov (United States)

    Kishi, J.; Ohtsubo, Y.; Nakamura, T.; Yaji, K.; Harasawa, A.; Komori, F.; Shin, S.; Rault, J. E.; Le Fèvre, P.; Bertran, F.; Taleb-Ibrahimi, A.; Nurmamat, M.; Yamane, H.; Ideta, S.; Tanaka, K.; Kimura, S.

    2017-11-01

    One-dimensional (1D) electronic states were discovered on the 1D surface atomic structure of Bi fabricated on semiconductor InSb(001) substrates by angle-resolved photoelectron spectroscopy (ARPES). The 1D state showed steep, Dirac-cone-like dispersion along the 1D atomic structure with a finite direct band gap opening as large as 150 meV. Moreover, spin-resolved ARPES revealed the spin polarization of the 1D unoccupied states as well as that of the occupied states, the orientation of which inverted depending on the wave-vector direction parallel to the 1D array on the surface. These results reveal that a spin-polarized quasi-1D carrier was realized on the surface of 1D Bi with highly efficient backscattering suppression, showing promise for use in future spintronics and energy-saving devices.

  20. A fast synthesis for Zintl phase compounds of Na 3SbTe 3, NaSbTe 2 and K 3SbTe 3 by microwave irradiation

    Science.gov (United States)

    Zhou, Gen-Tao; Pol, V. G.; Palchik, Oleg; Kerner, Riki; Sominski, Elena; Koltypin, Yuri; Gedanken, Aharon

    2004-01-01

    The microwave irradiation technique was used to prepare three Zintl phase compounds Na 3SbTe 3, NaSbTe 2 and K 3SbTe 3. The as-prepared products were analyzed and characterized by XRD, EDX and SEM techniques. Higher microwave oven power and shorter irradiation time are required for the synthesis of Na 3SbTe 3, whereas lower oven power and longer irradiation time are needed for NaSbTe 2. Moderate microwave irradiation conditions facilitate the formation of pure K 3SbTe 3. Pure phase of Na 3SbTe 3 are directly obtained by this technique for the first time. Compared with the traditional high-temperature solid-state synthesis, the microwave reaction required a considerable shortened reaction time for the preparation of the three Zintl compounds. The initial driving force for these reactions originates from the interaction of microwave electric field with alkali metals (Na and K) and Sb powders.

  1. Formation of Dense Pore Structure by Te Addition in Bi0.5Sb1.5Te3: An Approach to Minimize Lattice Thermal Conductivity

    Directory of Open Access Journals (Sweden)

    Syed Waqar Hasan

    2013-01-01

    Full Text Available We herein report the electronic and thermal transport properties of p-type Bi0.5Sb1.5Te3 polycrystalline bulks with dense pore structure. Dense pore structure was fabricated by vaporization of residual Te during the pressureless annealing of spark plasma sintered bulks of Te coated Bi0.5Sb1.5Te3 powders. The lattice thermal conductivity was effectively reduced to the value of 0.35 W m−1 K−1 at 300 K mainly due to the phonon scattering by pores, while the power factor was not significantly affected. An enhanced ZT of 1.24 at 300 K was obtained in spark plasma sintered and annealed bulks of 3 wt.% Te coated Bi0.5Sb1.5Te3 by these synergetic effects.

  2. Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Ni [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Jiang, Shiuh-Jen, E-mail: sjjiang@faculty.nsysu.edu.tw [Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Chen, Yen-Ling [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Sahayam, A.C. [National Centre for Compositional Characterisation of Materials (CCCM), Hyderabad (India)

    2015-02-20

    Highlights: • Determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions in a single run. • Accurate analysis using isotope dilution and standard addition methods. • Vapor generation ICP-MS yielded superior detection limits compared to ETV-ICP-MS. • No sample dissolution increased sample through put. • Analysis of GBW09305 Cosmetic (Cream) reference material for accuracy. - Abstract: A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v L-cysteine, 0.5 μg mL{sup −1} Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng g{sup −1} for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample.

  3. Magnetic susceptibility of Dirac fermions, Bi-Sb alloys, interacting Bloch fermions, dilute nonmagnetic alloys, and Kondo alloys

    Energy Technology Data Exchange (ETDEWEB)

    Buot, Felix A., E-mail: fbuot@gmu.edu [Computational Materials Science Center, George Mason University, Fairfax, VA 22030 (United States); TCSE Center, Spintronics Group, Physics Department, University of San Carlos, Talamban, Cebu 6000 (Philippines); C& LB Research Institute, Carmen, Cebu 6005 (Philippines); Otadoy, Roland E.S.; Rivero, Karla B. [TCSE Center, Spintronics Group, Physics Department, University of San Carlos, Talamban, Cebu 6000 (Philippines)

    2017-03-01

    Wide ranging interest in Dirac Hamiltonian is due to the emergence of novel materials, namely, graphene, topological insulators and superconductors, the newly-discovered Weyl semimetals, and still actively-sought after Majorana fermions in real materials. We give a brief review of the relativistic Dirac quantum mechanics and its impact in the developments of modern physics. The quantum band dynamics of Dirac Hamiltonian is crucial in resolving the giant diamagnetism of bismuth and Bi-Sb alloys. Quantitative agreement of the theory with the experiments on Bi-Sb alloys has been achieved, and physically meaningful contributions to the diamagnetism has been identified. We also treat relativistic Dirac fermion as an interband dynamics in uniform magnetic fields. For the interacting Bloch electrons, the role of translation symmetry for calculating the magnetic susceptibility avoids any approximation to second order in the field. The expressions for magnetic susceptibility of dilute nonmagnetic alloys give a firm theoretical foundation of the empirical formulas used in fitting experimental results. The unified treatment of all the above calculations is based on the lattice Weyl-Wigner formulation of discrete phase-space quantum mechanics. For completeness, the magnetic susceptibility of Kondo alloys is also given since Dirac fermions in conduction band and magnetic impurities exhibit Kondo effect.

  4. Quench hardening of Sb0.2 Bi1.8Te3, Bi2Te2.8Se0.2 and Sn0.2 Bi1.8Te3 single crystals

    Science.gov (United States)

    Soni, P. H.

    2018-02-01

    The V2-VI3 intermetallics are narrow band gap semiconductors and well known for their thermoelectric properties. They therefore offer a convenient route to tune band gap for manipulating thermoelectric parameters. The V group element Sb can be fruitfully used to substitute Bi in various proportions thus forming a psuedobinary solid solution. The electronic in general and the thermoelectric properties in particular of this psuedobinary have been amply reported. However there are no reports found on mechanical properties. I have used Sb0.2 Bi1.8Te3, Bi2Te2.8Se0.2 and Sn0.2 Bi1.8Te3single crystals grown using Bridgman technique for the quenching treatment followed by hardness testing. Vickers hardness tests were conducted on the cleavage planes of the crystals quenched from various high temperatures and the quench hardenening coefficient values have been determined. The hardness tests were carried out at various applied loads also to explore load dependence of the measured hardness. The results are reported in the paper.

  5. A Scanning Tunnelling Microscopy Study on an Alloyed Topological Insulator, Bi1.5Sb0.5Te1.7Se1.3

    Science.gov (United States)

    Ko, Wonhee; Jeon, Insu; Kim, Hyo Won; Kwon, Hyeokshin; Oh, Youngtek; Kahng, Se-Jong; Park, Joonbum; Kim, Jun Sung; Hwang, Sung Woo; Suh, Hwansoo

    2015-03-01

    Efficient doping of topological insulators while protecting its topological nature is key ingredient to realize topological devices. Engineering the chemical potential in the alloyed compound Bi2-xSbxTe3-ySey has been achieved by tuning its chemical composition. However, the effect of alloying in microscopic scale has not yet been fully investigated with local probes. Here we report on the atomic and electronic structures of Bi1.5Sb0.5Te1.7Se1.3 studied using scanning tunnelling microscopy/spectroscopy (STM/STS). Although there is significant surface disorder due to the alloying of constituent atoms, cleaved surfaces of the crystals present a well-ordered hexagonal lattice in STM topographs with 1 nm high quintuple layer steps. STS results reflect the band structure and indicate that the surface state and Fermi energy are both located inside the energy gap. The surface states do not show any electron back-scattering; due to their topological nature they are extremely robust. Landau levels generated by perpendicular magnetic field follow the massless Dirac fermions. This finding demonstrates that alloying is a promising route for efficient doping of topological insulators whilst keeping the topological surface state intact.

  6. Spin ½ Delafossite honeycomb compound Cu5SbO6.

    Science.gov (United States)

    Climent-Pascual, E; Norby, P; Andersen, N H; Stephens, P W; Zandbergen, H W; Larsen, J; Cava, R J

    2012-01-02

    Cu(5)SbO(6) is found to have a monoclinic, Delafossite-derived structure consisting of alternating layers of O-Cu(I)-O sticks and magnetic layers of Jahn-Teller distorted Cu(II)O(6) octahedra in an edge sharing honeycomb arrangement with Sb(V)O(6) octahedra. This yields the structural formula Cu(I)(3)Cu(II)(2)Sb(V)O(6). Variants with ordered and disordered layer stacking are observed, depending on the synthesis conditions. The spin ½ Cu(2+) ions form dimers in the honeycomb layer. The magnetic susceptibility measured between 5 and 300 K is characteristic of the presence of a singlet-triplet spin gap of 189 K. High resolution synchrotron X-ray diffraction studies indicate that changes in the intra- or interdimer distances between 300 and 20 K, such as might indicate an increase in strength of the Peierls-like distortion through the spin gap temperature, if present, are very small. A comparison to the NaFeO(2)-type Cu(2+) honeycomb compounds Na(3)Cu(2)SbO(6) and Na(2)Cu(2)TeO(6) is presented.

  7. Design and fabrication of thin film Bi-Sb and Bi-Cu thermopiles for IR thermal radiation detection

    CERN Document Server

    Afzalzadeh, R

    2003-01-01

    Thin film thermopiles are widely used as small size sensors, in particular to sense infra-red thermal radiations. In this paper a method for designing and fabrication of thin films Bi-Cu thermopiles in linear in linear array of 8 and 11 elements in series and mono-layer is introduced. Also, fabrication of of Bi-Cu thin film thermopiles, which are used as IR radiation sensors, made in multilayer from with 100 series junctions in circular shape are presented. The samples are fabricated on a PCB board with double-side copper laminated as a substrate. The results of our measurements show that the output voltage produced due to temperature difference between junctions, is very sensitive and linear to temperature difference.

  8. Effect of Nano-ZrW2O8 on the Thermoelectric Properties of Bi85Sb15/ZrW2O8 Composites

    Science.gov (United States)

    Zhou, Min; Chen, Zhen; Chu, Xinxin; Li, Laifeng

    2012-06-01

    In this study, Bi85Sb15/ x wt.% ZrW2O8 ( x = 0, 0.1, 0.5, 1) thermoelectric nanocomposites were prepared successfully by ball milling and spark plasma sintering. The effect of ZrW2O8 nanoparticles on the thermoelectric properties of the Bi85Sb15/ZrW2O8 composite was investigated. Thermal conductivity, Seebeck coefficient, and electrical conductivity were measured between 77 K and 300 K. x-Ray diffraction and scanning electron microscopy were adopted for microstructure characterization of the composites. The electrical transport properties are mainly discussed with regard to the microstructures. The results show that nanoinclusions did not grow during sintering. It is found that the thermal conductivity decreases with the addition of a small amount of ZrW2O8 nanoparticles, which serve as additional phonon-scattering centers. The obtained thermal conductivity is 0.5 W/m K for the Bi85Sb15/1 wt.% ZrW2O8 composite at 80 K, which is just half of the value for the Bi85Sb15 matrix. However, the electrical transport properties are degraded with increasing content of ZrW2O8. The calculated ZT is also degraded due to the poor electrical properties.

  9. Interaction between counter-propagating quantum Hall edge channels in the 3D topological insulator BiSbTeSe2

    NARCIS (Netherlands)

    Li, Chuan; De Ronde, Bob; Nikitin, Artem; Huang, Yingkai; Golden, Mark S.; De Visser, Anne; Brinkman, Alexander

    2017-01-01

    The quantum Hall effect is studied in the topological insulator BiSbTeSe2. By employing top- and back-gate electric fields at high magnetic field, the Landau levels of the Dirac cones in the top and bottom topological surface states can be tuned independently. When one surface is tuned to the

  10. Thermoelectric Properties of Alumina-Doped Bi0.4Sb1.6Te3 Nanocomposites Prepared through Mechanical Alloying and Vacuum Hot Pressing

    Directory of Open Access Journals (Sweden)

    Chung-Kwei Lin

    2015-11-01

    Full Text Available In this study, γ-Al2O3 particles were dispersed in p-type Bi0.4Sb1.6Te3 through mechanical alloying to form γ-Al2O3/Bi0.4Sb1.6Te3 composite powders. The composite powders were consolidated using vacuum hot pressing to produce nano- and microstructured composites. Thermoelectric (TE measurements indicated that adding an optimal amount of γ-Al2O3 nanoparticles improves the TE performance of the fabricated composites. High TE performances with figure of merit (ZT values as high as 1.22 and 1.21 were achieved at 373 and 398 K for samples containing 1 and 3 wt % γ-Al2O3 nanoparticles, respectively. These ZT values are higher than those of monolithic Bi0.4Sb1.6Te3 samples. The ZT values of the fabricated samples at 298–423 K are 1.0–1.22; these ZT characteristics make γ-Al2O3/Bi0.4Sb1.6Te3 composites suitable for power generation applications because no other material with a similarly high ZT value has been reported at this temperature range. The achieved high ZT value may be attributable to the unique nano- and microstructures in which γ-Al2O3 nanoparticles are dispersed among the grain boundary or in the matrix grain, as revealed by high-resolution transmission electron microscopy. The dispersed γ-Al2O3 nanoparticles thus increase phonon scattering sites and reduce thermal conductivity. The results indicated that the nano- and microstructured γ-Al2O3/Bi0.4Sb1.6Te3 alloy can serve as a high-performance material for application in TE devices.

  11. Ion beam irradiation effect on thermoelectric properties of Bi2Te3 and Sb2Te3 thin films

    Science.gov (United States)

    Fu, Gaosheng; Zuo, Lei; Lian, Jie; Wang, Yongqiang; Chen, Jie; Longtin, Jon; Xiao, Zhigang

    2015-09-01

    Thermoelectric energy harvesting is a very promising application in nuclear power plants for self-maintained wireless sensors. However, the effects of intensive radiation on the performance of thermoelectric materials under relevant reactor environments such as energetic neutrons are not fully understood. In this work, radiation effects of bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) thermoelectric thin film samples prepared by E-beam evaporation are investigated using Ne2+ ion irradiations at different fluences of 5 × 1014, 1015, 5 × 1015 and 1016 ions/cm2 with the focus on the transport and structural properties. Electrical conductivities, Seebeck coefficients and power factors are characterized as ion fluence changes. X-ray diffraction (XRD) and transmission electron microscopy (TEM) of the samples are obtained to assess how phase and microstructure influence the transport properties. Carrier concentration and Hall mobility are obtained from Hall effect measurements, which provide further insight into the electrical conductivity and Seebeck coefficient mechanisms. Positive effects of ion irradiations from Ne2+ on thermoelectric material property are observed to increase the power factor to 208% for Bi2Te3 and 337% for Sb2Te3 materials between fluence of 1 and 5 × 1015 cm2, due to the increasing of the electrical conductivity as a result of ionization radiation-enhanced crystallinity. However, under a higher fluence, 5 × 1015 cm2 in this case, the power factor starts to decrease accordingly, limiting the enhancements of thermoelectric materials properties under intensive radiation environment.

  12. Structural and optical properties of nano-powder-based (Sb1-x Bi x )2Te3 thin films

    Science.gov (United States)

    Adam, A. M.; Petkov, P.

    2017-08-01

    Sb2Te3-containing alloys can be employed for many applications, including in solar cells, thermoelectric devices, and phase-change devices. For the first time in the literature, Nano-powder-based samples of Bi-doped Sb2Te3 were used as sources to prepare the corresponding films. Such films were expected to show numerous interesting features such as solid-state operation, special scalability, low maintenance, and a long operating lifetime. The crystal structure of the synthesized powders and nano-powder films is studied and investigated in the present manuscript by means of x-ray diffraction, scanning electron microscopy and atomic force microscopy analysis. Better adhesion to the glass substrates is revealed for the films prepared in our work. High absorption in the visible region is observed, confirming potential applications in the field of recording devices. Optical studies confirmed direct and allowed transitions in both films with energy band gaps of 0.78-0.83 eV. Refractive index (n), and dielectric constants (ɛ r) and (ɛ i) are calculated and studied as a function of the wavelength.

  13. Effect of Sb substitution on the topological surface states in Bi2Se3 single crystals: a magneto-transport study

    Science.gov (United States)

    Devidas, T. R.; Amaladass, E. P.; Sharma, Shilpam; Mani, Awadhesh; Rajaraman, R.; Sundar, C. S.; Bharathi, A.

    2017-02-01

    Magneto-transport measurements have been carried out on Bi2-xSbxSe3 (x = 0, 0.05, 0.1, 0.3, 0.5) single crystals at 4.2 K temperature in the magnetic field range of -15 T to 15 T. Shubnikov-de Haas (SdH) oscillations of 2D nature were observed in samples with Sb concentration upto x = 0.3. The analyses of SdH oscillations observed in magneto-resistance data using Lifshitz-Kosevich equation reveal a systematic decrease in the Fermi surface area with Sb substitution. The Berry phase obtained from the Landau level fan diagram suggests the occurrence of 2D oscillations arising from a topological surface state (TSS) for Sb concentrations of x = 0, 0.05 and 0.1; while 2D oscillation seen at higher Sb concentration is attributed to surface 2D electron gas consequent to downward band bending.

  14. Observation of strong ferromagnetism in the half-Heusler compound CoTiSb system

    Energy Technology Data Exchange (ETDEWEB)

    Sedeek, K., E-mail: KamiliaSedeek@yahoo.com; Hantour, H.; Makram, N.; Said, Sh. A.

    2016-06-01

    Strong ferromagnetism has been detected in the semiconducting half-Heusler CoTiSb compound. The synthesis process was carried out by direct fusion of highly pure Co, Ti, and Sb in an evacuated quartz tube. The structural, micro structural and magnetic properties were investigated. The crystal structure was refined from X-ray powder diffraction data by the Rietveld method. Applying the search match program, three nano-crystalline phases of CoTiSb, Ti{sub 3}Sb and CoTi{sub 2} (50%, 33.3% and 16.7% respectively) were identified for the prepared system. The term “phase” is used to address the co-existence of different stable chemical composition for the same half-Heusler alloy. The scanning electron microscope SEM and the high resolution transmission electron microscope HR-TEM were applied to characterize the morphology, size, shape, crystallinity and lattice spacing. A mixture of ordered and disordered arrangement was detected. Well defined nano-crystalline structure with an average interatomic distance equals 0.333 nm and sharp diffraction spots were measured. Contrary to this, the HR-TEM and electron diffraction image shows distorted structured planes and smeared halo surrounded by weak rings. Thermo-magnetic measurements (M–T) have been measured between 640 °K and 920 °K. Clear magnetic phase transition is detected above 900 °K (T{sub c}), in addition to a second possible phase transition (T{sub FF}) around 740 °K. The latter is clarified by plotting ΔM/ΔT vs. T. To determine the type of the detected phase transitions, the field dependence of magnetization was measured at 300 °K and 740 °K. Arrot plots (M{sup 2}−H/M) confirm the ferromagnetic character at both temperatures. It may be reasonable to assume the T{sub FF} transition as an additional ferromagnetic contribution stemming from some sort of exchange interactions. A tentative magnetic phase diagram is given. Overall, the present results suggest that the prepared multiphases CoTiSb system does

  15. Modeling of half-Heusler compound NiMnSb within tight-binding approximation

    Science.gov (United States)

    Sugiyanto, Majidi, M. A.; Nanto, D.

    2017-07-01

    Heusler compounds are families of magnetic materials with general stoichiometry of either X2YZ (full-Heusler compound) or XYZ (half-Heusler compound), with X and Y being transition metal elements, and Z a main-group element. Their various potentials for technology development make them be still relevant as a subject of both experimental and theoretical studies. Half-Heusler compounds are generally crystallized in the C1b-type structure. The magnetic moments of such materials may be predicted using Slater-Pauling rule, giving m = (Nvalence electrons - 18)µB per formula unit. However, this simple counting rule does not always work for all compounds in this group. This motivates us to perform a theoretical study to investigate the mechanism of magnetic moment formation microscopically. As a case study, we focus on NiMnSb, a particular half-Heusler compound, for which comparison between existing experimental results and theoretical predictions of its magnetic moment has not yet been quite convincing. We model the system by constructing a tight-binding-based Hamiltonian, incorporating Hubbard repulsive as well as spin-spin interactions for the electrons occupying the d-orbitals. We solve the model using Green's function approach, and treat the interaction terms within the mean-field approximation. At this stage, we aim to formulate the computational algorithm for the overall calculation process. Our final goal is to compute the total magnetic moment per unit cell of this system and compare it with available experimental data.

  16. Preparation and characterization of Bi 2 S 3 compound semiconductor

    Indian Academy of Sciences (India)

    ... are grown by layer by layer mechanism.We studied the transport properties viz. Hall effect, resistivity, thermoelectric power and thermal conductivity on Bi2S3 pellets. Raman spectroscopy and thermal gravimetric analysis (TGA) were carried out on Bi2S3 single crystal for studying their optical and thermal behaviours.

  17. High Light Absorption and Charge Separation Efficiency at Low Applied Voltage from Sb-Doped SnO2/BiVO4 Core/Shell Nanorod-Array Photoanodes.

    Science.gov (United States)

    Zhou, Lite; Zhao, Chenqi; Giri, Binod; Allen, Patrick; Xu, Xiaowei; Joshi, Hrushikesh; Fan, Yangyang; Titova, Lyubov V; Rao, Pratap M

    2016-06-08

    BiVO4 has become the top-performing semiconductor among photoanodes for photoelectrochemical water oxidation. However, BiVO4 photoanodes are still limited to a fraction of the theoretically possible photocurrent at low applied voltages because of modest charge transport properties and a trade-off between light absorption and charge separation efficiencies. Here, we investigate photoanodes composed of thin layers of BiVO4 coated onto Sb-doped SnO2 (Sb:SnO2) nanorod-arrays (Sb:SnO2/BiVO4 NRAs) and demonstrate a high value for the product of light absorption and charge separation efficiencies (ηabs × ηsep) of ∼51% at an applied voltage of 0.6 V versus the reversible hydrogen electrode, as determined by integration of the quantum efficiency over the standard AM 1.5G spectrum. To the best of our knowledge, this is one of the highest ηabs × ηsep efficiencies achieved to date at this voltage for nanowire-core/BiVO4-shell photoanodes. Moreover, although WO3 has recently been extensively studied as a core nanowire material for core/shell BiVO4 photoanodes, the Sb:SnO2/BiVO4 NRAs generate larger photocurrents, especially at low applied voltages. In addition, we present control experiments on planar Sb:SnO2/BiVO4 and WO3/BiVO4 heterojunctions, which indicate that Sb:SnO2 is more favorable as a core material. These results indicate that integration of Sb:SnO2 nanorod cores with other successful strategies such as doping and coating with oxygen evolution catalysts can move the performance of BiVO4 and related semiconductors closer to their theoretical potential.

  18. The crystal structure of ferdowsiite Ag8Sb4(As,Sb)4S16 and its relations to other ABX2 (A=Ag; B=As,Sb,Bi; X=S,Se) structures

    DEFF Research Database (Denmark)

    Makovicky, Emil; Topa, Dan

    2014-01-01

    site has three short Sb-S bonds 2.503–2.645 Å. As and Sb in the mixed site were refined separately, with isotropic displacement coefficients. As has typical bond length values of 2.248–2.354 Å whereas Sb has 2.443–2.392 Å, i.e., the observed ligand positions are visibly influenced by the predominant...... of ferdowsiite, approximately Ag8Sb4(As,Sb)4S16, contains four distinct cation and four different anion sites in the asymmetric unit, all in general positions. Besides two Ag sites and one Sb site, the crystal structure contains one mixed As-Sb coordination polyhedron (0.63 As and 0.37 Sb in the site). The Sb1...

  19. Origin of the low critical observing temperature of the quantum anomalous Hall effect in V-doped (Bi, Sb)2Te3 film

    Science.gov (United States)

    Li, W.; Claassen, M.; Chang, Cui-Zu; Moritz, B.; Jia, T.; Zhang, C.; Rebec, S.; Lee, J. J.; Hashimoto, M.; Lu, D.-H.; Moore, R. G.; Moodera, J. S.; Devereaux, T. P.; Shen, Z.-X.

    2016-09-01

    The experimental realization of the quantum anomalous Hall (QAH) effect in magnetically-doped (Bi, Sb)2Te3 films stands out as a landmark of modern condensed matter physics. However, ultra-low temperatures down to few tens of mK are needed to reach the quantization of Hall resistance, which is two orders of magnitude lower than the ferromagnetic phase transition temperature of the films. Here, we systematically study the band structure of V-doped (Bi, Sb)2Te3 thin films by angle-resolved photoemission spectroscopy (ARPES) and show unambiguously that the bulk valence band (BVB) maximum lies higher in energy than the surface state Dirac point. Our results demonstrate clear evidence that localization of BVB carriers plays an active role and can account for the temperature discrepancy.

  20. La{sub 2}NiSb. A ternary ordered version of the Bi{sub 3}Ni type with highly polar bonding

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Konrad; Gerke, Birgit; Schwickert, Christian; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Isaeva, Anna [Technische Universitaet Dresden (Germany). Fachrichtung Chemie und Lebensmittelchemie; Ruck, Michael [Technische Universitaet Dresden (Germany). Fachrichtung Chemie und Lebensmittelchemie; Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany)

    2014-11-15

    The lanthanum-rich antimonide La{sub 2}NiSb was synthesized by annealing a cold-pressed pellet of the elements in a sealed silica glas tube at 1120 K. La{sub 2}NiSb was characterized by powder and single-crystal X-ray diffraction: ordered Bi{sub 3}Ni type, Pnma, Z = 4, a = 825.6(3), b = 452.2(2), c = 1195.5(4) pm, wR = 0.0695, 856 F{sup 2} values, 26 variables. The nickel atoms form infinite zig-zag chains (259 pm Ni-Ni) with trigonal-prismatic lanthanum coordination for each nickel atom. The antimony atoms cap the rectangular faces of the lanthanum prisms (336 pm La-Sb) and thereby coordinate also the nickel atoms (271 pm Ni-Sb). These rods run parallel to the b axis and form a herringbone pattern, similar to the FeB-type structure of GdNi. Although metallic conductivity is expected for La{sub 2}NiSb from DFT-based band structure calculations, the real-space bonding analysis shows prominent localization of electrons on antimonide anions and positively charged lanthanum cations. The chain substructure is strongly bonded by polar covalent Ni-Sb and multicenter Ni-Ni interactions. The nickel atoms, which are involved in multicenter bonding with adjacent nickel and lanthanum atoms, provide a conductivity pathway along the prismatic strands. {sup 121}Sb Moessbauer spectroscopic data at 78 K show a single signal at an isomer shift of -7.62(3) mm s{sup -1}, supporting the antimonide character. La{sub 2}NiSb shows weak paramagnetism with a susceptibility of 2.5 x 10{sup -3} emu mol{sup -1} at room temperature.

  1. Influence of the exchange and correlation functional on the structure of amorphous InSb and In{sub 3}SbTe{sub 2} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gabardi, Silvia; Caravati, Sebastiano; Bernasconi, Marco, E-mail: marco.bernasconi@mater.unimib.it [Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, I-20125 Milano (Italy); Los, Jan H.; Kühne, Thomas D. [Institute of Physical Chemistry and Center for Computational Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 7, D-55128 Mainz (Germany)

    2016-05-28

    We have investigated the structural, vibrational, and electronic properties of the amorphous phase of InSb and In{sub 3}SbTe{sub 2} compounds of interest for applications in phase change non-volatile memories. Models of the amorphous phase have been generated by quenching from the melt by molecular dynamics simulations based on density functional theory. In particular, we have studied the dependence of the structural properties on the choice of the exchange-correlation functional. It turns out that the use of the Becke-Lee-Yang-Parr functional provides models with a much larger fraction of In atoms in a tetrahedral bonding geometry with respect to previous results obtained with the most commonly used Perdew-Becke-Ernzerhof functional. This outcome is at odd with the properties of Ge{sub 2}Sb{sub 2}Te{sub 5} phase change compound for which the two exchange-correlation functionals yield very similar results on the structure of the amorphous phase.

  2. Determination of total Sb,Se Te, and Bi and evaluation of their inorganic species in garlic by hydride-generation-atomic-fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Matos Reyes, M.N.; Cervera, M.L.; Guardia, M. de la [University of Valencia, Department of Analytical Chemistry, Burjassot, Valencia (Spain)

    2009-07-15

    A sensitive and simple analytical method has been developed for determination of Sb(III), Sb(V), Se(IV), Se(VI), Te(IV), Te(VI), and Bi(III) in garlic samples by using hydride-generation-atomic-fluorescence spectrometry (HG-AFS). The method is based on a single extraction of the inorganic species by sonication at room temperature with 1 mol L{sup -1} H{sub 2}SO{sub 4} and washing of the solid phase with 0.1% (w/v) EDTA, followed by measurement of the corresponding hydrides generated under two different experimental conditions directly and after a pre-reduction step. The limit of detection of the method was 0.7 ng g{sup -1} for Sb(III), 1.0 ng g{sup -1} for Sb(V), 1.3 ng g{sup -1} for Se(IV), 1.0 ng g{sup -1} for Se(VI), 1.1 ng g{sup -1} for Te(IV), 0.5 ng g{sup -1} for Te(VI), and 0.9 ng g{sup -1} for Bi(III), in all cases expressed in terms of sample dry weight. (orig.)

  3. High thermoelectric performance of fullerene doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhou; Vemishetti, Aravindkumar; Ejembi, John Idoko; Wei, Guodong [Department of Physics, Southern University and A& M College, Baton Rouge, LA 70813 (United States); Zhang, Boliang; Wang, Li; Zhang, Yi; Guo, Shengmin [Mechanical & Industrial Engineering Department, Louisiana State University, Baton Rouge, LA 70803 (United States); Luo, Jia [Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803 (United States); Chepko, Corin; Dai, Qilin; Tang, JinKe [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Zhao, Guang-Lin, E-mail: guang-lin_zhao@subr.edu [Department of Physics, Southern University and A& M College, Baton Rouge, LA 70813 (United States)

    2016-03-15

    Highlights: • A high thermoelectric ZT 1.47 ± 0.07 (at 358 K) of Bi0.5Sb1.5Te3 bulk alloys was achieved by incorporation of small amount of C60. • The C60 doped Bi0.5Sb1.5Te3 bulk alloys have the potential as high performance thermoelectric materials near room temperature. • The thermal conductivity was dramatically reduced to 0.4 W/(mK) at 358 K after C60 doping. - Abstract: In this paper, we report our recent experimental findings on the enhancement of thermoelectric performance of C{sub 60} doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} bulk alloys. Incorporation of a small amount of C{sub 60} significantly reduces the crystalline particle size and leads to closely packed nanostructure, whilst slightly improve the electric conductivity in the measured temperature range. In addition, a minimum thermal conductivity of 0.4 W/(mK) at 358 K was observed, which is identified to be caused by the strong lattice phonon scattering at grain boundaries, yielding a high figure-of-merit ZT = 1.47 ± 0.07 at 358 K. Our results demonstrate that the materials can be used for the development of advanced thermoelectrics.

  4. Anomalous quantization trajectory and parity anomaly in Co cluster decorated BiSbTeSe2 nanodevices.

    Science.gov (United States)

    Zhang, Shuai; Pi, Li; Wang, Rui; Yu, Geliang; Pan, Xing-Chen; Wei, Zhongxia; Zhang, Jinglei; Xi, Chuanying; Bai, Zhanbin; Fei, Fucong; Wang, Mingyu; Liao, Jian; Li, Yongqing; Wang, Xuefeng; Song, Fengqi; Zhang, Yuheng; Wang, Baigeng; Xing, Dingyu; Wang, Guanghou

    2017-10-17

    Dirac Fermions with different helicities exist on the top and bottom surfaces of topological insulators, offering a rare opportunity to break the degeneracy protected by the no-go theorem. Through the application of Co clusters, quantum Hall plateaus were modulated for the topological insulator BiSbTeSe2, allowing an optimized surface transport. Here, using renormalization group flow diagrams, we show the extraction of two sets of converging points in the conductivity tensor space, revealing that the top surface exhibits an anomalous quantization trajectory, while the bottom surface retains the 1/2 quantization. Co clusters are believed to induce a sizeable Zeeman gap ( > 4.8 meV) through antiferromagnetic exchange coupling, which delays the Landau level hybridization on the top surface for a moderate magnetic field. A quasi-half-integer plateau also appears at -7.2 Tesla. This allows us to study the interesting physics of parity anomaly, and paves the way for further studies simulating exotic particles in condensed matter physics.The topological surface states usually appear in pairs in a topological insulator, with one on the top surface and the other on the bottom surface. Here, Zhang et al. utilize Co cluster to induce a Zeeman gap on one surface through antiferromagnetic exchange coupling, and observe a quasi-half-integer plateau, suggesting the parity anomaly of Dirac fermions.

  5. 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.

  6. CoBi{sub 3}. A binary cobalt-bismuth compound and superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Ulrich; Tence, Sophie; Janson, Oleg; Koz, Cevriye; Krellner, Cornelius; Burkhardt, Ulrich; Rosner, Helge; Steglich, Frank; Grin, Yuri [MPI fuer Chemische Physik fester Stoffe, Dresden (Germany)

    2013-09-09

    The first binary phase in the system Co-Bi was obtained by high-pressure high-temperature synthesis. The NiBi{sub 3}-type structure motif comprises cobalt-centered monocapped bismuth prisms with covalent Co-Bi interactions. The polyhedra are condensed into infinite columns, which are arranged in the form of a distorted hexagonal rod packing. The new compound is a superconductor with a T{sub c} slightly below 0.5 K. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Study of the structural phase transitions of (CH 3NH 3) 3Sb 2Cl 9 (MACA) and (CH 3NH 3) 3Bi 2Cl 9 (MACB) by infrared spectroscopy

    Science.gov (United States)

    Bator, G.; Jakubas, R.; Malarski, Z.

    1991-06-01

    Infrared spectra of polycrystalline (CH 3NH 3) 3Sb 2Cl 9 and (CH 3NH 3) 3Bi 2Cl 9 have been studied in the temperature range 90-300 K. A systematic temperature dependence study of the internal modes has been carried out. We discuss the effects of the dynamic state of methylammonium (MA) cations on their vibrational spectra. The results show that the dynamics of MA cations in both compounds is similar in higher (about 300 K) and lower temperature (in the vicinity of 100 K) regions. Substantial differences are revealed in the intermediate temperature interval. The results are in good agreement with earlier dielectric, calorimetric and 1H NMR studies.

  8. Diffusion coefficients for Tl, Pb, Cd, In, Zn, Bi, As, Mo and Sb in hydrous rhyolite at 100-200 MPa

    Science.gov (United States)

    Berlo, Kim; Brooker, Richard; Wilke, Max

    2014-05-01

    A series of experiments have been conducted to determine the diffusivities of Tl, Pb, Cd, In, Zn, Bi, As, Mo and Sb in hydrous rhyolitic melt. Diffusion experiments used two adjoining glass cylinder of the same hydrous composition, one doped with the elements of interest at ~ 100 ppm. These couples were rapidly heated to 850, 1000 and 1150°C at 100-200 MPa for a few hours. After quenching the sectioned charges were analyzed by both synchrotron XRF (The Diamond Light Source) and LA-ICP-MS (University of Oxford). The data shows excellent correlation between these two techniques. The diffusion profiles were fitted to a 1-D diffusion couple equation to determine the diffusivities and fitting to the different temperature runs defined the Arrhenius parameters. We find that for 850°C the diffusion coefficients follow the trend Tl>Pb>Cd>Zn>In>Bi>As>Sb>Mo. Additional experiments were performed with either S or Cl added (to both sides of the diffusion couple). In general S increases the diffusion rate of all metals except Mo and Sb, which diffuse slower in the presence of S. Chlorine also speeds up the diffusion of metals with the exception of In, Mo and Sb. The systematic change in diffusivities of these metals and their different behaviour in the presence of the ligands that are also observed to be significant in volcanic gases, are important in determining the distribution of these metals during degassing (e.g. MacKenzie and Canil, 2008). This is particularly important in a dynamic environment such as a volcanic conduit. There are also implications for economic exploration and well as hazard mitigation.

  9. Stability enhancement and electronic tunability of two-dimensional SbIV compounds via surface functionalization

    Science.gov (United States)

    Zhou, Wenhan; Guo, Shiying; Liu, Xuhai; Cai, Bo; Song, Xiufeng; Zhu, Zhen; Zhang, Shengli

    2018-01-01

    We propose a family of hydrogenated- and halogenated-SbIV (SbIVX-2) materials that simultaneously have two-dimensional (2D) structures, high stability and appealing electronic properties. Based on first-principles total-energy and vibrational-spectra calculations, SbIVX-2 monolayers are found both thermally and dynamically stable. Varying IV and X elements can rationally tune the electronic properties of SbIVX-2 monolayers, effectively modulating the band gap from 0 to 3.42 eV. Regarding such superior stability and broad band-gap range, SbIVX-2 monolayers are expected to be synthesized in experiments and taken as promising candidates for low-dimensional electronic and optoelectronic devices, such as blue-to-ultraviolet light-emitting diodes (LED) and photodetectors.

  10. Multiband superconductivity in BiS2-based layered compounds

    Science.gov (United States)

    Griffith, M. A.; Puel, T. O.; Continentino, M. A.; Martins, G. B.

    2017-08-01

    A mean-field treatment is presented of a square lattice two-orbital-model for \\text{Bi}{{\\text{S}}2} taking into account intra- and inter-orbital superconductivity. A rich phase diagram involving both types of superconductivity is presented as a function of the ratio between the couplings of electrons in the same and different orbitals (η ={{\\text{V}}\\text{XX}}/{{\\text{V}}\\text{XY}} ) and electron doping x. With the help of a quantity we call orbital-mixing ratio, denoted as R(φ ) , the phase diagram is analyzed using a simple and intuitive picture based on how R(φ ) varies as electron doping increases. The predictive power of R(φ ) suggests that it could be a useful tool in qualitatively (or even semi-quantitatively) analyzing multiband superconductivity in BCS-like superconductors.

  11. Effects of Lu and Tm Doping on Thermoelectric Properties of Bi2Te3 Compound

    Science.gov (United States)

    Yaprintsev, Maxim; Lyubushkin, Roman; Soklakova, Oxana; Ivanov, Oleg

    2017-11-01

    The Bi2Te3, Bi1.9Lu0.1Te3 and Bi1.9Tm0.1Te3 thermoelectrics of n-type conductivity have been prepared by the microwave-solvothermal method and spark plasma sintering. These compounds behave as degenerate semiconductors from room temperature up to temperature T d ≈ 470 K. Within this temperature range the temperature behavior of the specific electrical resistivity is due to the temperature changes of electron mobility determined by acoustic and optical phonon scattering. Above T d, an onset of intrinsic conductivity takes place when electrons and holes are present. At the Lu and Tm doping, the Seebeck coefficient increases, while the specific electrical resistivity and total thermal conductivity decrease within the temperature 290-630 K range. The increase of the electrical resistivity is related to the increase of electron concentration since the Tm and Lu atoms are donor centres in the Bi2Te3 lattice. The increase of the density-of-state effective mass for conduction band can be responsible for the increase of the Seebeck coefficient. The decrease of the total thermal conductivity in doped Bi2Te3 is attributed to point defects like the antisite defects and Lu or Tm atoms substituting for the Bi sites. In addition, reducing the electron thermal conductivity due to forming a narrow impurity (Lu or Tm) band having high and sharp density-of-states near the Fermi level can effectively decrease the total thermal conductivity. The thermoelectric figure-of-merit is enhanced from ˜ 0.4 for undoped Bi2Te3 up to ˜ 0.7 for Bi1.9Tm0.1Te3 and ˜ 0.9 for Bi1.9Lu0.1Te3.

  12. Synthesis and characterization of Bi{sub 1.56}Sb{sub 1.48}Co{sub 0.96}O{sub 7} pyrochlore sun-light-responsive photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Naceur, Benhadria, E-mail: nacer1974@yahoo.fr [Laboratory of Inorganic Materials Chemistry and Application, Department of Materials Engineering, University of Science and Technology of Oran (USTO M.B), BP 1505, El M’naouar, 31000 Oran (Algeria); Abdelkader, Elaziouti, E-mail: elaziouti_a@yahoo.com [Laboratory of Inorganic Materials Chemistry and Application, Department of Materials Engineering, University of Science and Technology of Oran (USTO M.B), BP 1505, El M’naouar, 31000 Oran (Algeria); Dr Moulay Tahar University, Saida (Algeria); Nadjia, Laouedj, E-mail: nlaouedj@yahoo.fr [Laboratory of Inorganic Materials Chemistry and Application, Department of Materials Engineering, University of Science and Technology of Oran (USTO M.B), BP 1505, El M’naouar, 31000 Oran (Algeria); Dr Moulay Tahar University, Saida (Algeria); Sellami, Mayouf, E-mail: Mourad7dz@yahoo.fr [Laboratory of Inorganic Materials Chemistry and Application, Department of Materials Engineering, University of Science and Technology of Oran (USTO M.B), BP 1505, El M’naouar, 31000 Oran (Algeria); Noureddine, Bettahar, E-mail: nbettahar2001@yahoo.fr [Laboratory of Inorganic Materials Chemistry and Application, Department of Materials Engineering, University of Science and Technology of Oran (USTO M.B), BP 1505, El M’naouar, 31000 Oran (Algeria)

    2016-02-15

    Graphical abstract: Heterogeneous photo Fenton process with dye sensitized mechanism of RhB by Bi{sub 1.56}Sb{sub 1.48}Co{sub 0.96}O{sub 7} compound. - Highlights: • Bi{sub 1.56}Sb{sub 1.48}Co{sub 0.96}O{sub 7} (BSCO) catalyst was synthesized by improved solid state reaction method. • BSCO/H{sub 2}O{sub 2}/UVA and BSCO/H{sub 2}O{sub 2}/SL catalyst systems exhibit excellent photocatalytic activities for rhodamine B. • The photocatalytic degradation was preceded via heterogeneous photo Fenton mechanism process. • ·OH radicals are the main reactive species for the degradation of RhB. - Abstract: Novel nanostructure pyrochlore Bi{sub 1.56}Sb{sub 1.48}Co{sub 0.96}O{sub 7} was successfully synthesized via solid state reaction method in air. The as-synthesized photocatalyst was characterized by X-ray diffraction, Scanning electron microscopy and UV–vis diffuse reflectance spectroscopy techniques. The results showed that the BSCO was crystallized with the pyrochlore-type structure, cubic crystal system and space group Fd3m. The average particle size and band gap for BSCO were D = 76.29 nm and E{sub g} = 1.50 eV respectively. Under the optimum conditions for discoloration of the dye: initial concentration of 20 mg L{sup −1} RhB, pH 7, 25 °C, 0.5 mL H{sub 2}O{sub 2} and BSCO/dye mass ration of 1 g L{sup −1}, 97.77 and 90.16% of RhB were removed with BSCO/H{sub 2}O{sub 2} photocatalytic system within 60 min of irradiation time under UVA- and SL irradiations respectively. Pseudo-second-order kinetic model gave the best fit, with highest correlation coefficients (R{sup 2} ≥ 0.99). On the base of these results, the mechanism of the enhancement of the discoloration efficiency was discussed. .

  13. New layered compounds with honeycomb ordering: Li3Ni2BiO6, Li3NiM'BiO6 (M' = Mg, Cu, Zn), and the delafossite Ag3Ni2BiO6.

    Science.gov (United States)

    Berthelot, Romain; Schmidt, Whitney; Muir, Sean; Eilertsen, James; Etienne, Laetitia; Sleight, A W; Subramanian, M A

    2012-05-07

    The new layered compound Li(3)Ni(2)BiO(6) has been prepared by a solid-state reaction. It crystallizes in the monoclinic C2/m space group; its lamellar structure is characterized by a honeycomb ordering between Ni(2+) and Bi(5+) within the slabs, while Li(+) ions occupy octahedral sites in the interslab space. Stacking defects weakly alter the XRD pattern. By substitution of half of the nickel ions, the new phases Li(3)NiM'BiO(6) (M' = Mg, Cu, Zn) isostructural with Li(3)Ni(2)BiO(6) have been synthesized under similar conditions. All these compounds demonstrate paramagnetic behavior at high temperature, and Li(3)Ni(2)BiO(6) exhibits an antiferromagnetic ordering at 5.5 K. By topotactic molten salt ionic exchange, the new delafossite compound Ag(3)Ni(2)BiO(6) has been also obtained and characterized.

  14. Discovery of a superconducting Cu-Bi intermetallic compound by high-pressure synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, Samantha M.; Walsh, James P.S.; Malliakas, Christos D.; Freedman, Danna E. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Amsler, Maximilian; Wolverton, Chris [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Yu, Tony; Wang, Yanbin [Chicago Univ., IL (United States). Center for Advanced Radiation Sources; Goedecker, Stefan [Basel Univ. (Switzerland). Dept. of Physics

    2016-10-17

    A new intermetallic compound, the first to be structurally identified in the Cu-Bi binary system, is reported. This compound is accessed by high-pressure reaction of the elements. Its detailed characterization, physical property measurements, and ab initio calculations are described. The commensurate crystal structure of Cu{sub 11}Bi{sub 7} is a unique variation of the NiAs structure type. Temperature-dependent electrical resistivity and heat capacity measurements reveal a bulk superconducting transition at T{sub c}=1.36 K. Density functional theory calculations further demonstrate that Cu{sub 11}Bi{sub 7} can be stabilized (relative to decomposition into the elements) at high pressure and temperature. These results highlight the ability of high-pressure syntheses to allow for inroads into heretofore-undiscovered intermetallic systems for which no thermodynamically stable binaries are known.

  15. Discovery of a Superconducting Cu-Bi Intermetallic Compound by High-Pressure Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, Samantha M. [Department of Chemistry, Northwestern University, Evanston IL 60208 USA; Walsh, James P. S. [Department of Chemistry, Northwestern University, Evanston IL 60208 USA; Amsler, Maximilian [Department of Materials Science and Engineering, Northwestern University, Evanston IL 60208 USA; Malliakas, Christos D. [Department of Chemistry, Northwestern University, Evanston IL 60208 USA; Yu, Tony [Center for Advanced Radiation Sources, The University of Chicago, Chicago IL 60637 USA; Goedecker, Stefan [Department of Physics, Universität Basel, Kingelbergstr. 82 4056 Basel Switzerland; Wang, Yanbin [Center for Advanced Radiation Sources, The University of Chicago, Chicago IL 60637 USA; Wolverton, Chris [Department of Materials Science and Engineering, Northwestern University, Evanston IL 60208 USA; Freedman, Danna E. [Department of Chemistry, Northwestern University, Evanston IL 60208 USA

    2016-09-26

    A new intermetallic compound, the first to be structurally identified in the Cu-Bi binary system, is reported. This compound is accessed by high-pressure reaction of the elements. Its detailed characterization, physical property measurements, and ab initio calculations are described. The commensurate crystal structure of Cu11Bi7 is a unique variation of the NiAs structure type. Temperature-dependent electrical resistivity and heat capacity measurements reveal a bulk superconducting transition at Tc=1.36 K. Density functional theory calculations further demonstrate that Cu11Bi7 can be stabilized (relative to decomposition into the elements) at high pressure and temperature. These results highlight the ability of high-pressure syntheses to allow for inroads into heretofore-undiscovered intermetallic systems for which no thermodynamically stable binaries are known.

  16. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2.

    Science.gov (United States)

    Liu, Jinyu; Hu, Jin; Cao, Huibo; Zhu, Yanglin; Chuang, Alyssa; Graf, D; Adams, D J; Radmanesh, S M A; Spinu, L; Chiorescu, I; Mao, Zhiqiang

    2016-07-28

    Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm(2)V(-1)S(-1)) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons.

  17. Structural characterization of half-metallic Heusler compound NiMnSb

    Energy Technology Data Exchange (ETDEWEB)

    Nowicki, L. E-mail: lech.nowicki@fuw.edu.pl; Abdul-Kader, A.M.; Bach, P.; Schmidt, G.; Molenkamp, L.W.; Turos, A.; Karczewski, G

    2004-06-01

    High resolution X-ray diffraction (HRXRD) and Rutherford backscattering/channeling (RBS/c) techniques were used to characterize layers of NiMnSb grown by molecular beam epitaxy (MBE) on InP with a In{sub x}Ga{sub 1-x}As buffer. Angular scans in the channeling mode reveal that the crystal structure of NiMnSb is tetragonally deformed with c/a=1.010{+-}0.002, in agreement with HRXRD data. Although HRXRD demonstrates the good quality of the pseudomorphic NiMnSb layers the channeling studies show that about 20% of atoms in the layers do not occupy lattice sites in the [0 0 1] rows of NiMnSb. The possible mechanisms responsible for the observed disorder are discussed.

  18. Multielemental Determination of As, Bi, Ge, Sb, and Sn in Agricultural Samples Using Hydride Generation Coupled to Microwave-Induced Plasma Optical Emission Spectrometry.

    Science.gov (United States)

    Machado, Raquel C; Amaral, Clarice D B; Nóbrega, Joaquim A; Araujo Nogueira, Ana Rita

    2017-06-14

    A microwave-induced plasma optical emission spectrometer with N2-based plasma was combined with a multimode sample introduction system (MSIS) for hydride generation (HG) and multielemental determination of As, Bi, Ge, Sb, and Sn in samples of forage, bovine liver, powdered milk, agricultural gypsum, rice, and mineral fertilizer, using a single condition of prereduction and reduction. The accuracy of the developed analytical method was evaluated using certified reference materials of water and mineral fertilizer, and recoveries ranged from 95 to 106%. Addition and recovery experiments were carried out, and the recoveries varied from 85 to 117% for all samples evaluated. The limits of detection for As, Bi, Ge, Sb, and Sn were 0.46, 0.09, 0.19, 0.46, and 5.2 μg/L, respectively, for liquid samples, and 0.18, 0.04, 0.08, 0.19, and 2.1 mg/kg, respectively, for solid samples. The method proposed offers a simple, fast, multielemental, and robust alternative for successful determination of all five analytes in agricultural samples with low operational cost without compromising analytical performance.

  19. High-performance dispenser printed MA p-type Bi(0.5)Sb(1.5)Te(3) flexible thermoelectric generators for powering wireless sensor networks.

    Science.gov (United States)

    Madan, Deepa; Wang, Zuoqian; Chen, Alic; Wright, Paul K; Evans, James W

    2013-11-27

    This work presents a novel method to synthesize p-type composite thermoelectric materials to print scalable thermoelectric generator (TEG) devices in a cost-effective way. A maximum ZT of 0.2 was achieved for mechanically alloyed (MA) p-type Bi0.5Sb1.5Te3 (8 wt % extra Te additive)-epoxy composite films cured at 250 °C. A 50% increase in Seebeck coefficient as a result of adding 8 wt % extra Te in stoichiometric Bi0.5Sb1.5Te3 contributed to the increase in ZT. To demonstrate cost-effective and scalable manufacturing, we fabricated a sixty element thermoelectric generator prototype with 5.0 mm × 600 μm × 120 μm printed dimensions on a custom designed polyimide substrate with thick metal contacts. The prototype TEG device produced a power output of 20.5 μW at 0.15 mA and 130 mV for a temperature difference of 20 K resulting in a device areal power density of 152 μW/cm(2). This power is sufficient for low power applications such as wireless sensor network (WSN) devices.

  20. Investigation of the Microstructure and Thermoelectric Properties of P-Type BiSbTe Alloys by Usage of Different Revolutions Per Minute (RPM During Mechanical Milling

    Directory of Open Access Journals (Sweden)

    Yoon S.-M.

    2017-06-01

    Full Text Available In this work, p-type Bi0.5Sb1.5Te3 alloys were fabricated by high-energy ball milling (MA and spark plasma sintering. Different revolutions per minute (RPMs were used in the MA process, and their effect on microstructure, and thermoelectric properties of p-type Bi0.5Sb1.5Te3 were systematically investigated. The crystal structure of milled powders and sintered samples were characterized using X-ray diffraction. All the powders exhibited the same morphology albeit with slight differences find at 1100 RPM conditions. A slight grain size refinement was observed on the fracture surfaces from 500 to 1100 RPM specimens. The temperature dependence of Seebeck coefficient, electrical conductivity, and power factors were measured as a function of temperature with different RPM conditions. The power factor shows almost same (~3.5 W/mK2 at RT for all samples due to unchanged Seebeck and electrical conductivity values. The peak ZT of 1.07 at 375K is obtained for 1100 RPM specimen due to low thermal conductivity.

  1. Effects of Matte Grade on the Distribution of Minor Elements (Pb, Zn, As, Sb, and Bi in the Bottom Blown Copper Smelting Process

    Directory of Open Access Journals (Sweden)

    Qinmeng Wang

    2017-11-01

    Full Text Available With increasing impurity contents in concentrates, the control of the minor elements is an important issue for the oxygen bottom blown copper smelting process (Shuikoushan process or SKS process. In this work, the distribution behaviors of the minor elements (such as Pb, Zn, As, Sb, and Bi among the matte, slag, and gas phases as a function of matte grades was investigated by adjusting the ratios of oxygen/ore in the SKS process. With a matte grade around 70%, about 82% As and 70% Bi enters the gas phase, and about 70% Sb and 64% Zn reports to the slag phase, while 55% lead enters the matte phase. The tendency of changes in the distribution of the minor elements in the SKS process is different from that in the Isasmelt process and the Flash smelting process. It may be concluded from this study that the distributions of the minor elements could be optimized to reduce adverse effects in the SKS process by regulating the matte grade.

  2. Magnetic properties of nearly stoichiometric CeAuBi{sub 2} heavy fermion compound

    Energy Technology Data Exchange (ETDEWEB)

    Adriano, C.; Jesus, C. B. R.; Pagliuso, P. G. [Instituto de Física “Gleb Wataghin,” UNICAMP, Campinas-SP, 13083-859 (Brazil); Rosa, P. F. S. [Instituto de Física “Gleb Wataghin,” UNICAMP, Campinas-SP, 13083-859 (Brazil); University of California, Irvine, California 92697-4574 (United States); Grant, T.; Fisk, Z. [University of California, Irvine, California 92697-4574 (United States); Garcia, D. J. [Instituto Balseiro, Centro Atomico Bariloche, CNEA and CONICET, 8400 Bariloche (Argentina)

    2015-05-07

    Motivated by the interesting magnetic anisotropy found in the heavy fermion family CeTX{sub 2} (T = transition metal and X = pnictogen), here, we study the novel parent compound CeAu{sub 1−x}Bi{sub 2−y} by combining magnetization, pressure dependent electrical resistivity, and heat-capacity measurements. The magnetic properties of our nearly stoichiometric single crystal sample of CeAu{sub 1−x}Bi{sub 2−y} (x = 0.92 and y = 1.6) revealed an antiferromagnetic ordering at T{sub N} = 12 K with an easy axis along the c-direction. The field dependent magnetization data at low temperatures reveal the existence of a spin-flop transition when the field is applied along the c-axis (H{sub c} ∼ 7.5 T and T = 5 K). The heat capacity and pressure dependent resistivity data suggest that CeAu{sub 0.92}Bi{sub 1.6} exhibits a weak heavy fermion behavior with strongly localized Ce{sup 3+} 4f electrons. Furthermore, the systematic analysis using a mean field model including anisotropic nearest-neighbors interactions and the tetragonal crystalline electric field (CEF) Hamiltonian allows us to extract a CEF scheme and two different values for the anisotropic J{sub RKKY} exchange parameters between the Ce{sup 3+} ions in this compound. Thus, we discuss a scenario, considering both the anisotropic magnetic interactions and the tetragonal CEF effects, in the CeAu{sub 1−x}Bi{sub 2−y} compounds, and we compare our results with the isostructural compound CeCuBi{sub 2}.

  3. The thermoelectric properties of CoSb3 compound doped with Te and Sn synthesized at different pressure

    Science.gov (United States)

    Jiang, Yiping; Jia, Xiaopeng; Ma, Hongan

    2017-10-01

    The skutterudite CoSb2.75Te0.20Sn0.05 compound was synthesized successfully by high pressure and high temperature (HPHT) method using Co, Sb, Te and Sn powder as raw materials. The effects of pressure on its structure and the thermoelectric properties are investigated systematically from 300 K to 800 K. The electrical resistivity and the absolute value of the Seebeck coefficient for the sample increases with rising synthetic pressure. The thermal conductivity of the sample decreases with synthetic pressure and temperature rising in the range of 300-800 K. In this study, the maximum dimensionless figure of merit (ZT) value of 1.17 has been achieved at 793 K, 3 GPa for this thermoelectric material.

  4. Effect of Mechanical Deformation on Thermoelectric Properties of p-Type (Bi0.225Sb0.7752Te3 Alloys

    Directory of Open Access Journals (Sweden)

    Sung-Jin Jung

    2013-01-01

    Full Text Available The effect of mechanical deformation and annealing on thermoelectric properties of p-type (Bi0.225Sb0.775Te3 was performed. The ingots were prepared by melting, followed by quenching method using source materials with compositions of (Bi0.225Sb0.7752Te3. Rectangular shaped specimens (5×5×12 mm3 were cut from ingots and then cold-pressed at 700 MPa for 2 to 20 times by changing the press direction perpendicular to previous one. The cold-pressed samples have been annealed in a quartz ampoule at 573 K. The grain size of the samples was controlled by the number of cold-pressing process and annealing time. Fine grain structure with a grain size of not more than 10 μm is obtained in highly deformed samples. The Seebeck coefficient of the deformed samples were gradually increased with annealing and converged to the similar value of about 225 μV/K after 30 hrs. The small grain size in highly deformed sample enables a rapid increase of Seebeck coefficient with annealing time (~2 hrs., indicating that the thermal energy needed to recrystallize in highly deformed specimens is lower than that in low deformed specimens. Z values are rapidly increased with annealing time especially in highly deformed alloys, and converge to about 3.0×10−3/K at room temperature. A higher thermoelectric performance could be expected by the optimization of composition and microstructural adjustment. The present study experimentally demonstrates a simple and cost-effective method for fabricating Bi-Te-based alloys with higher thermoelectric performance.

  5. Spin 1/2 Delafossite Honeycomb Compound Cu5SbO6

    DEFF Research Database (Denmark)

    Climent-Pascual, E.; Norby, Poul; Andersen, Niels Hessel

    2012-01-01

    Cu5SbO6 is found to have a monoclinic, Delafossite-derived structure consisting of alternating layers of O–Cu(I)–O sticks and magnetic layers of Jahn–Teller distorted Cu(II)O6 octahedra in an edge sharing honeycomb arrangement with Sb(V)O6 octahedra. This yields the structural formula Cu(I)3Cu(II)2......Sb(V)O6. Variants with ordered and disordered layer stacking are observed, depending on the synthesis conditions. The spin 1/2 Cu2+ ions form dimers in the honeycomb layer. The magnetic susceptibility measured between 5 and 300 K is characteristic of the presence of a singlet–triplet spin gap of 189...

  6. Electrocatalytic property of PtBi and PtPb line compounds via DFT

    Science.gov (United States)

    Wang, Lin-Lin; Johnson, D. D.

    2007-03-01

    A major obstacle to practical, mass market fuel cell (e.g. hydrogen and direct methanol) technology is CO poisoning of Pt anode. Pt alloys, such as disordered PtxRu(1-x), are known to have an increased CO-tolerance. There has been significant effort to understand the mechanism for increased CO- tolerance and to design better catalyst via alloyed nanoparticles and surface alloys. Alternatively, Pt intermetallic compounds, such as with Bi and Pb, have been observed to improve dramatically the CO-tolerance. [E. Casado- Rivera et al. ChemPhysChem 4, 193 (2003) and J. Am. Chem. Soc. 126, 4043 (2004)] Here we use density functional theory to study the adsorptions of CO, H and OH on these materials. We find that (100) and (110) surfaces of PtBi and PtPb line compounds have lower cleavage energy than (001) surface. Adsorption energies and electronic structure are examined to explain the increased CO-tolerance.

  7. Lead-free perovskite solar cells using Sb and Bi-based A3B2X9 and A3BX6 crystals with normal and inverse cell structures

    Science.gov (United States)

    Baranwal, Ajay Kumar; Masutani, Hideaki; Sugita, Hidetaka; Kanda, Hiroyuki; Kanaya, Shusaku; Shibayama, Naoyuki; Sanehira, Yoshitaka; Ikegami, Masashi; Numata, Youhei; Yamada, Kouji; Miyasaka, Tsutomu; Umeyama, Tomokazu; Imahori, Hiroshi; Ito, Seigo

    2017-09-01

    Research of CH3NH3PbI3 perovskite solar cells had significant attention as the candidate of new future energy. Due to the toxicity, however, lead (Pb) free photon harvesting layer should be discovered to replace the present CH3NH3PbI3 perovskite. In place of lead, we have tried antimony (Sb) and bismuth (Bi) with organic and metal monovalent cations (CH3NH3 +, Ag+ and Cu+). Therefore, in this work, lead-free photo-absorber layers of (CH3NH3)3Bi2I9, (CH3NH3)3Sb2I9, (CH3NH3)3SbBiI9, Ag3BiI6, Ag3BiI3(SCN)3 and Cu3BiI6 were processed by solution deposition way to be solar cells. About the structure of solar cells, we have compared the normal (n-i-p: TiO2-perovskite-spiro OMeTAD) and inverted (p-i-n: NiO-perovskite-PCBM) structures. The normal (n-i-p)-structured solar cells performed better conversion efficiencies, basically. But, these environmental friendly photon absorber layers showed the uneven surface morphology with a particular grow pattern depend on the substrate (TiO2 or NiO). We have considered that the unevenness of surface morphology can deteriorate the photovoltaic performance and can hinder future prospect of these lead-free photon harvesting layers. However, we found new interesting finding about the progress of devices by the interface of NiO/Sb3+ and TiO2/Cu3BiI6, which should be addressed in the future study.

  8. Photoemission of heavy fermion superconductor PrOs{sub 4} Sb{sub 12} and other Pr compounds

    Energy Technology Data Exchange (ETDEWEB)

    Imada, S. [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan)]. E-mail: imada@mp.es.osaka-u.ac.jp; Fukuda, Y. [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Yamasaki, A. [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Sekiyama, A. [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan); Sugawara, H. [Faculty of Integrated Arts and Sciences, Tokushima University, Tokushima 770-8502 (Japan); Sato, H. [Graduate School of Science, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Ochiai, A. [Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Suga, S. [Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan)

    2005-06-15

    PrOs{sub 4} Sb{sub 12} and other Pr compounds have been studied by means of bulk sensitive photoemission. The Pr 4f electronic state was probed by means of the Pr 3d->4f resonant photoemission (RPES). RPES spectrum was found to depend upon the photon energy (h{nu}) especially above the Pr 3d{sub 5/2} peak. It seems that the h{nu} dependence is weak enough before the absorption intensity reaches the half of the peak.

  9. [(K0.5Na0.5)NbO3–LiSbO3]– xBiFe0.8Co0.2O3 lead-free ...

    Indian Academy of Sciences (India)

    LiSbO3]–xBiFe0.8Co0.2O3(KNN–. LS–xBFC) were prepared by a conventional sintering technique. The effect of BFC content on the structure, piezo- electric and electrical properties of KNN–LS ceramics was investigated. The results reveal that ...

  10. Radiochemical neutron activation analysis for 36 elements in geological material: Au, Ag, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Sn, Te, Tl, U, and Zn as well as Sc, Y, and REE

    Energy Technology Data Exchange (ETDEWEB)

    Anders, E; Wolf, R; Morgan, J W; Ebihara, M; Woodrow, A B; Janssens, M J; Hertogen, J

    1988-01-01

    In lunar and terrestrial rocks and in meteorites, the radiochemical neutron activation method decribed here enables determination of the 21 trace and ultratrace elements Ag, Au, Bi, Br, Cd, Cs, Ga, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Te, Tl, U, Zn, as well as 13 rare earth elements (REE), Sc and Y. Materials, techniques and procedures are discussed. 81 refs.

  11. Crystal, magnetic, calorimetric and electronic structure investigation of GdScGe1–x Sb x compounds

    Science.gov (United States)

    Guillou, F.; Pathak, A. K.; Hackett, T. A.; Paudyal, D.; Mudryk, Y.; Pecharsky, V. K.

    2017-12-01

    Experimental investigations of crystal structure, magnetism and heat capacity of compounds in the pseudoternary GdScGe-GdScSb system combined with density functional theory projections have been employed to clarify the interplay between the crystal structure and magnetism in this series of RTX materials (R  =  rare-earth, T   =  transition metal and X  =  p-block element). We demonstrate that the CeScSi-type structure adopted by GdScGe and CeFeSi-type structure adopted by GdScSb coexist over a limited range of compositions 0.65 ≤slant x ≤slant 0.9 . Antimony for Ge substitutions in GdScGe result in an anisotropic expansion of the unit cell of the parent that is most pronounced along the c axis. We believe that such expansion acts as the driving force for the instability of the double layer CeScSi-type structure of the parent germanide. Extensive, yet limited Sb substitutions 0 ≤slant x magnetization. With a further increase in Sb content, the first compositions showing the presence of the CeFeSi-type structure of the antimonide, x ≈ 0.7 , coincide with the appearance of an antiferromagnetic phase. The application of a finite magnetic field reveals a jump in magnetization toward a fully saturated ferromagnetic state. This antiferro–ferromagnetic transformation is not associated with a sizeable latent heat, as confirmed by heat capacity measurements. The electronic structure calculations for x = 0.75 indicate that the key factor in the conversion from the ferromagnetic CeScSi-type to the antiferromagnetic CeFeSi-type structure is the disappearance of the induced magnetic moments on Sc. For the parent antimonide, heat capacity measurements indicate an additional transition below the main antiferromagnetic transition.

  12. Comparison of crystal growth and thermoelectric properties of n-type Bi-Se-Te and p-type Bi-Sb-Te nanocrystalline thin films: Effects of homogeneous irradiation with an electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Takashiri, Masayuki, E-mail: takashiri@tokai-u.jp; Imai, Kazuo; Uyama, Masato; Nishi, Yoshitake [Department of Materials Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Hagino, Harutoshi; Miyazaki, Koji [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, 1-1 Sensui, Tobata-ku, Kitakyushu 804-8550 (Japan); Tanaka, Saburo [Department of Mechanical Engineering, College of Engineering, Nihon University, Nakagawara, Tokusada, Tamuramachi, Koriyama, Fukushima 963-8642 (Japan)

    2014-06-07

    The effects of homogenous electron beam (EB) irradiation on the crystal growth and thermoelectric properties of n-type Bi-Se-Te and p-type Bi-Sb-Te thin films were investigated. Both types of thin films were prepared by flash evaporation, after which homogeneous EB irradiation was performed at an acceleration voltage of 0.17 MeV. For the n-type thin films, nanodots with a diameter of less than 10 nm were observed on the surface of rice-like nanostructures, and crystallization and crystal orientation were improved by EB irradiation. The resulting enhancement of mobility led to increased electrical conductivity and thermoelectric power factor for the n-type thin films. In contrast, the crystallization and crystal orientation of the p-type thin films were not influenced by EB irradiation. The carrier concentration increased and mobility decreased with increased EB irradiation dose, possibly because of the generation of defects. As a result, the thermoelectric power factor of p-type thin films was not improved by EB irradiation. The different crystallization behavior of the n-type and p-type thin films is attributed to atomic rearrangement during EB irradiation. Selenium in the n-type thin films is more likely to undergo atomic rearrangement than the other atoms present, so only the crystallinity of the n-type Bi-Se-Te thin films was enhanced.

  13. Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong

    2016-04-10

    tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

  14. Performance calculations of thermoelectric module p-type leg composed of (Bi2Te3x(Sb2Te31-x

    Directory of Open Access Journals (Sweden)

    Musiał Michał

    2016-01-01

    Full Text Available The paper presents the results of numerical and simple analytical performance investigations of p-type leg of thermoelectric module (TEM. Calculations of (Bi2Te3x(Sb2Te31-x p-type leg for different chemical compositions (x=0.16,0.20,0.24,0.26 have been carried out to estimate the power output and conversion efficiency. Study has been performed for constant and temperature dependent thermoelectric parameters: Seebeck coefficient α, electrical resistivity ρ and thermal conductivity k. Results of modelling for constant material parameters fit very well with the analytical solution, pointing that numerical tools can be useful in development of thermoelectric modules and generators.

  15. Spectral and spatial resolving of photoelectric property of femtosecond laser drilled holes of GaSb(1-x)Bi(x).

    Science.gov (United States)

    Pan, C B; Zha, F X; Song, Y X; Shao, J; Dai, Y; Chen, X R; Ye, J Y; Wang, S M

    2015-07-15

    Femtosecond laser drilled holes of GaSbBi were characterized by the joint measurements of photoconductivity (PC) spectroscopy and laser-beam-induced current (LBIC) mapping. The excitation light in PC was focused down to 60 μm presenting the spectral information of local electronic property of individual holes. A redshift of energy band edge of about 6-8 meV was observed by the PC measurement when the excitation light irradiated on the laser drilled holes. The spatial resolving of photoelectric property was achieved by the LBIC mapping which shows "pseudo-holes" with much larger dimensions than the geometric sizes of the holes. The reduced LBIC current with the pseudo-holes is associated with the redshift effect indicating that the electronic property of the rim areas of the holes is modified by the femtosecond laser drilling.

  16. Hydride generation atomic fluorescence spectrometric determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter using multivariate optimization

    Energy Technology Data Exchange (ETDEWEB)

    Moscoso-Perez, Carmen [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Moreda-Pineiro, Jorge [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)]. E-mail: jmoreda@udc.es; Lopez-Mahia, Purificacion [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Muniategui-Lorenzo, Soledad [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Fernandez-Fernandez, Esther [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Prada-Rodriguez, Dario [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)

    2004-11-22

    A highly sensitive and simple method, based on hydride generation and atomic fluorescence detection, has been developed for the determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter samples. Atmospheric particulates matter was collected on glass fiber filters using a medium volume sampler (PM1 particulate matter). Two-level factorial designs have been used to optimise the hydride generation atomic fluorescence spectrometry (HG-AFS) procedure. The effects of several parameters affecting the hydride generation efficiency (hydrochloric acid, sodium tetrahydroborate and potassium iodide concentrations and flow rates) have been evaluated using a Plackett-Burman experimental design. In addition, parameters affecting the hydride measurement (delay, analysis and memory times) have been also investigated. The significant parameters obtained (sodium tetrahydroborate concentration, sodium tetrahydroborate flow rate and analysis time for As; hydrochloric acid concentration and sodium tetrahydroborate flow rate for Se(IV); and sodium tetrahydroborate concentration and sodium tetrahydroborate flow rate for Te(IV)) have been optimized by using 2{sup n} + star central composite design. Hydrochloric acid concentration and sodium tetrahydroborate flow rate were the significant parameters obtained for Sb and Bi determination, respectively. Using a univariate approach these parameters were optimized. The accuracy of methods have been verified by using several certified reference materials: SRM 1648 (urban particulate matter) and SRM 1649a (urban dust). Detection limits in the range of 6 x 10{sup -3} to 0.2 ng m{sup -3} have been achieved. The developed methods were applied to several atmospheric particulate matter samples corresponding to A Coruna city (NW Spain)

  17. Effect of Substitutional Pb Doping on Bipolar and Lattice Thermal Conductivity in p-Type Bi0.48Sb1.52Te₃.

    Science.gov (United States)

    Kim, Hyun-Sik; Lee, Kyu Hyoung; Yoo, Joonyeon; Youn, Jehun; Roh, Jong Wook; Kim, Sang-Il; Kim, Sung Wng

    2017-07-06

    Cation substitutional doping is an effective approach to modifying the electronic and thermal transports in Bi₂Te₃-based thermoelectric alloys. Here we present a comprehensive analysis of the electrical and thermal conductivities of polycrystalline Pb-doped p-type bulk Bi0.48Sb1.52Te₃. Pb doping significantly increased the electrical conductivity up to ~2700 S/cm at x = 0.02 in Bi0.48-xPbxSb1.52Te₃ due to the increase in hole carrier concentration. Even though the total thermal conductivity increased as Pb was added, due to the increased hole carrier concentration, the thermal conductivity was reduced by 14-22% if the contribution of the increased hole carrier concentration was excluded. To further understand the origin of reduction in the thermal conductivity, we first estimated the contribution of bipolar conduction to thermal conductivity from a two-parabolic band model, which is an extension of the single parabolic band model. Thereafter, the contribution of additional point defect scattering caused by Pb substitution (Pb in the cation site) was analyzed using the Debye-Callaway model. We found that Pb doping significantly suppressed both the bipolar thermal conduction and lattice thermal conductivity simultaneously, while the bipolar contribution to the total thermal conductivity reduction increased at high temperatures. At Pb doping of x = 0.02, the bipolar thermal conductivity decreased by ~30% from 0.47 W/mK to 0.33 W/mK at 480 K, which accounts for 70% of the total reduction.

  18. Non-Gaussian resistance noise in misfit layer compounds: Bi-Se-Cr

    Science.gov (United States)

    Peng, Lintao; Freedman, Alex; Clarke, Samantha; Freedman, Danna; Grayson, M.

    Misfit layer ternary compounds Bi-Se-Cr have been synthesized and structurally and magnetically characterized. However, the nature of the magnetic ordering below the transition temperature remains debatable between ferromagnetic and spin-glass. These misfit layer compounds consist of two alternating chalcogenide layers of CrSe2 and BiSe along the c-axis. Whereas the a-axis is lattice matched, the lattice mismatch along the b-axis introduces non-periodic modulation of atomic position leading to quasi-crystalline order along the b-axis alone. We explore unconventional electrical transport properties in the noise spectrum of these compounds. After thinning down the compounds to nanoscale, Van der Pauw devices are fabricated with standard electron beam lithography process. Large resistance noise was observed at temperature below the Cure temperature. The magnitude of resistance noise is much greater than trivial intrinsic noises like thermal Johnson noise and increases as temperature decreases. The probability density function of the relative noise shows 2-4 peaks among different observations which indicate strong non-Gaussian statistic property suggesting glassy behaviors in this material.

  19. Theoretical study of the new zintl phases compounds K{sub 2}ACdSb{sub 2} (A=(Sr, Ba))

    Energy Technology Data Exchange (ETDEWEB)

    Azam, Sikander [New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Reshak, A.H., E-mail: maalidph@yahoo.co.uk [New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia)

    2015-05-01

    The electronic structure and optical properties of K{sub 2}SrCdSb{sub 2} and K{sub 2}BaCdSb{sub 2} compounds are computed using the full potential linearized augmented plane wave (FP-LAPW) method as implemented in WIEN2k code. In this perspective, the local density approximation (LDA), generalized gradient approximation (GGA) and Engel and Vosko approximation (EV-GGA) were used for the exchange correlation potential. The calculated band structure shows a direct band gap of about 0.344/0.20 eV (LDA), 0.463/0.285 eV (GGA) and 0.904/0.707 eV (EV-GGA) for K{sub 2}SrCdSb{sub 2}/K{sub 2}BaCdSb{sub 2} compounds. The part of different bands was scrutinized from total and partial density of states curves. There is strong hybridization between Sr-s and Sr-p states and also between Cd-d and Sb-s states in the valence band. The electronic charge density has also been studied in the (200) crystallographic plane. The K, Sr/Ba, Cd and Sb atoms shows ionic bonding. Besides this, the optical properties, including the dielectric function are obtained and analyzed in details.

  20. Thermoelectric and Transport Properties of N-Type Bi{sub 2−x}Sb{sub x}Te{sub 3−y}Se{sub y} Solid Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Eum, A-Young; Kim, Il-Ho [Korea National University of Transportation, Chungju (Korea, Republic of)

    2017-03-15

    Bi{sub 2−x}Sb{sub x}Te{sub 3−y}Se{sub y} (x = 0.1, 0.2 and y = 0.15, 0.3) solid solutions were prepared using encapsulated melting and hot pressing. The lattice constants decreased with increases in the Sb and the Se contents, which revealed the successful formation of solid solutions. The relative densities of the hot-pressed specimens were 95 - 98%. All specimens exhibited n-type conduction at temperatures from 323 K to 523 K, and the electrical conductivity slightly decreased with increasing temperature. With an increase in the Se content, the Seebeck coefficient increased while the electrical and the thermal conductivities decreased; thus, the dimensionless figure of merit could be improved. The maximum dimensionless figure of merit ZT{sub max} = 0.89 was obtained at 423 K for Bi{sub 1.8}Sb{sub 0.2}Te{sub 2.7}Se{sub 0.3}. An increase in the Sb content resulted in a decrease in the lattice thermal conductivity because of an increase in alloy scattering, but its effect on the electrical properties was not superior to the effect of Se substitution. Therefore, Sb substitution could effectively control the thermal properties while Se substitution could effectively control the electrical properties.

  1. Optimization of Bi2O3, TiO2, and Sb2O3 doped ZnO-based low-voltage varistor ceramic to maximize nonlinear electrical properties.

    Science.gov (United States)

    Dorraj, Masoumeh; Zakaria, Azmi; Abdollahi, Yadollah; Hashim, Mansor; Moosavi, Seyedehmaryam

    2014-01-01

    In ZnO-based low voltage varistor, the two essential features of microstructure determining its nonlinear response are the formation Bi-enriched active grain boundaries as well as a controlled ZnO grain size by secondary spinel-type phases. Besides, the microstructure and phase composition are strongly affected by the dopant concentration during sintering process. In this study, the optimal dopant levels of Bi2O3, TiO2, and Sb2O3 to achieve maximized nonlinear electrical property (alpha) were quantified by the response surface methodology (RSM). RSM was also used to understand the significance and interaction of the factors affecting the response. Variables were determined as the molar ratio of Bi2O3, TiO2, and Sb2O3. The alpha was chosen as response in the study. The 5-level-3-factor central composite design, with 20 runs, was used to conduct the experiments by ball milling method. A quadratic model was established as a functional relationship between three independent variables and alpha. According to the results, the optimum values of Bi2O3, TiO2, and Sb2O3 were obtained 0.52, 0.50, and 0.30, respectively. Under optimal conditions the predicted alpha (9.47) was calculated using optimal coded values from the model and the theoretical value is in good agreement with the value (9.43) obtained by confirmation experiment.

  2. Optimization of Bi2O3, TiO2, and Sb2O3 Doped ZnO-Based Low-Voltage Varistor Ceramic to Maximize Nonlinear Electrical Properties

    Directory of Open Access Journals (Sweden)

    Masoumeh Dorraj

    2014-01-01

    Full Text Available In ZnO-based low voltage varistor, the two essential features of microstructure determining its nonlinear response are the formation Bi-enriched active grain boundaries as well as a controlled ZnO grain size by secondary spinel-type phases. Besides, the microstructure and phase composition are strongly affected by the dopant concentration during sintering process. In this study, the optimal dopant levels of Bi2O3, TiO2, and Sb2O3 to achieve maximized nonlinear electrical property (alpha were quantified by the response surface methodology (RSM. RSM was also used to understand the significance and interaction of the factors affecting the response. Variables were determined as the molar ratio of Bi2O3, TiO2, and Sb2O3. The alpha was chosen as response in the study. The 5-level-3-factor central composite design, with 20 runs, was used to conduct the experiments by ball milling method. A quadratic model was established as a functional relationship between three independent variables and alpha. According to the results, the optimum values of Bi2O3, TiO2, and Sb2O3 were obtained 0.52, 0.50, and 0.30, respectively. Under optimal conditions the predicted alpha (9.47 was calculated using optimal coded values from the model and the theoretical value is in good agreement with the value (9.43 obtained by confirmation experiment.

  3. Heavily Cr-doped (Bi,Sb2Te3 as a ferromagnetic insulator with electrically tunable conductivity

    Directory of Open Access Journals (Sweden)

    Yunbo Ou

    2016-08-01

    Full Text Available With molecular beam epitaxy we have grown Cry(BixSb1-x2-yTe3 thin films with homogeneous distribution of Cr dopants and Curie temperature up to 77 K. The films with Cr concentration y ≥ 0.39 are found to be topologically trivial, highly insulating ferromagnets, whose conductivity can be tuned over two orders of magnitude by gate voltage. The ferromagnetic insulators with electrically tunable conductivity can be used to realize the quantum anomalous Hall effect at higher temperature in topological insulator heterostructures and to develop field effect devices for spintronic applications.

  4. Hole density and acceptor-type defects in MBE-grown GaSb1-x  Bi x

    Science.gov (United States)

    Segercrantz, N.; Slotte, J.; Makkonen, I.; Tuomisto, F.; Sandall, I. C.; Ashwin, M. J.; Veal, T. D.

    2017-07-01

    We study acceptor-type defects in \\text{GaS}{{\\text{b}}1-x} \\text{B}{{\\text{i}}x} grown by molecular beam epitaxy. The hole density of the \\text{GaS}{{\\text{b}}1-x} \\text{B}{{\\text{i}}x} layers, from capacitance-voltage measurements of Schottky diodes, is higher than that of the binary alloys and increases linearly up to 1019 \\text{c}{{\\text{m}}-3} with the Bi content. Positron annihilation spectroscopy and ab initio calculations show that both Ga vacancies and Ga antisites contribute to the hole density and that the proportion of the two acceptor-type defects vary in the layers. The modification of the band gap due to Bi incorporation as well as the growth parameters are suggested to affect the concentrations of acceptor-type defects.

  5. Isothermal section of the phase diagram and crystal structures of the compounds in the ternary system Tm-Cu-Sb at 870 K

    Science.gov (United States)

    Fedyna, L. O.; Fedorchuk, A. O.; Mykhalichko, V. M.; Shpyrka, Z. M.; Fedyna, M. F.

    2017-07-01

    The isothermal section of the Tm-Cu-Sb phase diagram at 870 K was constructed using X-ray phase analysis. The existence of one ternary compound was confirmed - TmCu1-xGe2 (x = 0.109) (structure type HfCuSi2, space group P4/nmm, Pearson code tP8-0.22, a = 4.24170(2), c = 9.73942(9) Å). New ternary copper antimonides Tm3Cu20+xSb11-x (x = 2) (structure type Dy3Cu20+xSb11-x, space group F-43 m, Pearson code cF272, a = 16.55784(4) Å) and TmCu4-xSb2 (x = 1.065) (structure type ErFe4Ge2 (LTM), space group Pnnm, Pearson code oP14-2.13, a = 7.00565(6), b = 7.83582(6), c = 4.25051(3) Å) were found. The crystal structures of compounds were refined by full-profile Rietveld method using X-ray powder diffraction data. The solubility of the third component in all binary phases was found to be negligible. The crystal structures of known ternary antimonides were analyzed and relationship among the crystal structures of compounds in the ternary system Tm-Cu-Sb was illustrated.

  6. Structural and thermomechanical properties of the zinc-blende AlX (X = P, As, Sb) compounds

    Science.gov (United States)

    Ha, Vu Thi Thanh; Hung, Vu Van; Hanh, Pham Thi Minh; Nguyen, Viet Tuyen; Hieu, Ho Khac

    2017-08-01

    The structural and thermomechanical properties of zinc-blende aluminum class of III-V compounds have been studied based on the statistical moment method (SMM) in quantum statistical mechanics. Within the SMM scheme, we derived the analytical expressions of the nearest-neighbor distance, thermal expansion coefficient, atomic mean-square displacement and elastic moduli (Young’s modulus, bulk modulus and shear modulus). Numerical calculations have been performed for zinc-blende AlX (X = As, P, Sb) at ambient conditions up to the temperature of 1000 K. Our results are in good and reasonable agreements with earlier measurements and can provide useful references for future experimental and theoretical works. This research presents a systematic approach to investigate the thermodynamic and mechanical properties of materials.

  7. Single-crystalline study of the ferromagnetic kondo compound UCu{sub 0.9}Sb{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Bukowski, Z. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocIaw (Poland); Troc, R. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocIaw (Poland); Stepien-Damm, J. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocIaw (Poland); SuIkowski, C. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocIaw (Poland); Tran, V.H. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocIaw (Poland)]. E-mail: V.H.Tran@int.pan.wroc.pl

    2005-11-10

    Single crystals of UCu{sub 0.9}Sb{sub 2} have been grown using the self-flux method and studied by means of X-ray diffraction, magnetic and electrical transport measurements. This compound crystallizes in a tetragonal structure of the HfCuSi{sub 2}-type (space group P4/nmm) and orders ferromagnetically below T {sub C} = 113 K with the easy-magnetization direction along the c-axis exhibiting a large magnetocrystalline anisotropy in both the ordered and paramagnetic states. The electrical resistivity, magnetoresistivity and thermoelectric power data are also given. A Kondo-like behaviour of the resistivity in the paramagnetic state is reported.

  8. Theoretical investigation on the magnetic and electric properties in TbSb compound through an anisotropic microscopic model

    Energy Technology Data Exchange (ETDEWEB)

    Ranke, P. J. von, E-mail: von.ranke@uol.com.br; Ribeiro, P. O.; Alho, B. P.; Alvarenga, T. S. T.; Nobrega, E. P.; Caldas, A.; Sousa, V. S. R.; Lopes, P. H. O.; Oliveira, N. A. de [Instituto de Física, Universidade do Estado do Rio de Janeiro–UERJ, Rua São Francisco Xavier, 524, 20550-013 Rio de Janeiro (RJ) (Brazil); Carvalho, A. Magnus G. [Laboratório Nacional de Luz Síncrotron, CNPEM, 13083-970 Campinas, São Paulo (Brazil)

    2016-05-14

    We report the strong correlations between the magnetoresistivity and the magnetic entropy change in the cubic antiferromagnetic TbSb compound. The theoretical investigation was performed through a microscopic model which takes into account the crystalline electrical field anisotropy, exchange coupling interactions between the up and down magnetic sublattices, and the Zeeman interaction. The easy magnetization directions changes from 〈001〉 to 〈110〉 and then to 〈111〉 observed experimentally was successfully theoretically described. Also, the calculation of the temperature dependence of electric resistivity showed good agreement with the experimental data. Theoretical predictions were calculated for the temperature dependence of the magnetic entropy and resistivity changes upon magnetic field variation. Besides, the difference in the spin up and down sublattices resistivity was investigated.

  9. Electrical transport and optical properties of the incommensurate intergrowth compounds (SbS)(1.15)(TiS2)(n) with n=1 and 2

    NARCIS (Netherlands)

    Ren, Y; Ruscher, CH; Haas, C; Wiegers, GA

    2002-01-01

    The in-plane electrical transport and optical properties of the incommensurate intergrowth compounds (SbS)(1.15)(TiS2)(n) with n = 1, 2 have been investigated by means of measurements of the electrical resistivity, Hall coefficient and thermopower in the temperature range from 4.2 to 350 K, and by

  10. Growth behavior of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} thin films on graphene substrate grown by plasma-enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Wan [Thin Film Materials Research Group, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); School of Electrical and Electronic Engineering, Yonsei University, Seoul (Korea, Republic of); Kim, Gun Hwan; Kang, Min A.; An, Ki-Seok; Lee, Young Kuk [Thin Film Materials Research Group, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Kang, Seong Gu [School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Kim, Hyungjun [School of Electrical and Electronic Engineering, Yonsei University, Seoul (Korea, Republic of)

    2017-03-15

    A comparative study of the substrate effect on the growth mechanism of chalcogenide Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} thin films was carried out. Obvious microstructural discrepancy in both the as-deposited Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} thin films was observed when grown on graphene or SiO{sub 2}/Si substrate. Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} thin films deposited on the graphene substrate were observed to be grown epitaxially along c-axis and show very smooth surface compared to that on SiO{sub 2}/Si substrate. Based on the experimental results of this study, the initial adsorption sites on graphene substrate during deposition process, which had been discussed theoretically, could be demonstrated empirically. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Dirac-surface-state-dominated spin to charge current conversion in the topological insulator (Bi0.22Sb0.78)2Te3 films at room temperature

    Science.gov (United States)

    Mendes, J. B. S.; Alves Santos, O.; Holanda, J.; Loreto, R. P.; de Araujo, C. I. L.; Chang, Cui-Zu; Moodera, J. S.; Azevedo, A.; Rezende, S. M.

    2017-11-01

    We report the spin-to-charge current conversion in an intrinsic topological insulator (TI) (Bi0.22Sb0.78) 2T e3 film at room temperature. The spin currents are generated in a thin layer of permalloy (Py) by two different processes, the spin pumping effect (SPE) and the spin Seebeck effect (SSE). In the first, we use microwave-driven ferromagnetic resonance of the Py film to generate a SPE spin current that is injected into the TI (Bi0.22Sb0.78) 2T e3 layer in direct contact with Py. In the second, we use the SSE in the longitudinal configuration in Py without contamination by the anomalous Nernst effect, which was made possible with a thin NiO layer between the Py and (Bi0.22Sb0.78) 2T e3 layers. The spin-to-charge current conversion is dominated by the TI surface states and is attributed to the inverse Edelstein effect (IEE), which is made possible by the spin-momentum locking in the electron Fermi contours due to the Rashba field. The measurements by the two techniques yield very similar values for the IEE parameter, which are larger than the reported values in the previous studies on topological insulators.

  12. Fabrication and Enhanced Thermoelectric Properties of Alumina Nanoparticle-Dispersed Bi0.5Sb1.5Te3 Matrix Composites

    Directory of Open Access Journals (Sweden)

    Kyung Tae Kim

    2013-01-01

    Full Text Available Alumina nanoparticle-dispersed bismuth-antimony-tellurium matrix (Al2O3/BST composite powders were fabricated by using ball milling process of alumina nanoparticle about 10 nm and p-type bismuth telluride nanopowders prepared from the mechanochemical process (MCP. The fabricated Al2O3/BST composite powders were a few hundreds of nanometer in size, with a clear Bi0.5Sb1.5Te3 phase. The composite powders were consolidated into p-type bulk composite by spark plasma sintering process. High-resolution TEM images reveal that alumina nanoparticles were dispersed among the grain boundary or in the matrix grain. The sintered 0.3 vol.% Al2O3/BST composite exhibited significantly improved power factor and reduced thermal conductivity in the temperature ranging from 293 to 473 K compared to those of pure BST. From these results, the highly increased ZT value of 1.5 was obtained from 0.3 vol.% Al2O3/BST composite at 323 K.

  13. First principles study of (Cd, Hg, In, Tl, Sn, Pb, As, Sb, Bi, Se) modified Pt(111), Pt(100) and Pt(211) electrodes as CO oxidation catalysts

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir

    2015-01-01

    CO oxidation is a prototype reaction for studying oxidation of small organic molecules. Certain adatom modified Pt electrodes have a large promotional effect on CO oxidation. However, the effect is often coverage dependent, and has a limited effect due to short lifetimes of the adatoms. The cover......CO oxidation is a prototype reaction for studying oxidation of small organic molecules. Certain adatom modified Pt electrodes have a large promotional effect on CO oxidation. However, the effect is often coverage dependent, and has a limited effect due to short lifetimes of the adatoms....... The coverage dependence as a function of potential for ten different adatom species (Cd, Hg, In, Tl, Sn, Pb, As, Sb, Bi, Se) on bare and CO saturated Pt(111), Pt(100) and Pt(211) surfaces has been established by means of Density Functional Theory calculations. Most of the adatoms are very stable under standard...... conditions and remain anchored to the surface until high potentials in supporting electrolytes. The stability is contingent on the electrode roughness and reduces in the following order: Pt(211) ≈ Pt(100) > Pt(111), except for Se adatoms, in which case the trend is reversed. The activity for CO oxidation...

  14. Improvement of thermoelectric properties of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} films grown on graphene substrate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Wan [Thin Film Materials Research Group, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); School of Electrical and Electronic Engineering, Yonsei University, Seoul (Korea, Republic of); Kim, Gun Hwan; Choi, Ji Woon; An, Ki-Seok; Lee, Young Kuk [Thin Film Materials Research Group, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Kim, Jin-Sang [Center for Electronic Materials, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Kim, Hyungjun [School of Electrical and Electronic Engineering, Yonsei University, Seoul (Korea, Republic of)

    2017-06-15

    A study of substrate effect on the thermoelectric (TE) properties of Bi{sub 2}Te{sub 3} (BT) and Sb{sub 2}Te{sub 3} (ST) thin films grown by plasma-enhanced chemical vapor deposition (PECVD) was performed. Graphene substrates which have small lattice mismatch with BT and ST were used for the preparation of highly oriented BT and ST thin films. Carrier mobility of the epitaxial BT and ST films grown on the graphene substrates increased as the deposition temperature increased, which was not observed in that of SiO{sub 2}/Si substrates. Seebeck coefficients of the as-grown BT and ST films were observed to be maintained even though carrier concentration increased in the epitaxial BT and ST films on graphene substrate. Although Seebeck coefficient was not improved, power factor of the as-grown BT and ST films was considerably enhanced due to the increase of electrical conductivity resulting from the high carrier mobility and moderate carrier concentration in the epitaxial BT and ST films. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Binary Phase Diagrams and Thermodynamic Properties of Silicon and Essential Doping Elements (Al, As, B, Bi, Ga, In, N, P, Sb and Tl)

    Science.gov (United States)

    Mostafa, Ahmad; Medraj, Mamoun

    2017-01-01

    Fabrication of solar and electronic silicon wafers involves direct contact between solid, liquid and gas phases at near equilibrium conditions. Understanding of the phase diagrams and thermochemical properties of the Si-dopant binary systems is essential for providing processing conditions and for understanding the phase formation and transformation. In this work, ten Si-based binary phase diagrams, including Si with group IIIA elements (Al, B, Ga, In and Tl) and with group VA elements (As, Bi, N, P and Sb), have been reviewed. Each of these systems has been critically discussed on both aspects of phase diagram and thermodynamic properties. The available experimental data and thermodynamic parameters in the literature have been summarized and assessed thoroughly to provide consistent understanding of each system. Some systems were re-calculated to obtain a combination of the best evaluated phase diagram and a set of optimized thermodynamic parameters. As doping levels of solar and electronic silicon are of high technological importance, diffusion data has been presented to serve as a useful reference on the properties, behavior and quantities of metal impurities in silicon. This paper is meant to bridge the theoretical understanding of phase diagrams with the research and development of solar-grade silicon production, relying on the available information in the literature and our own analysis. PMID:28773034

  16. Binary Phase Diagrams and Thermodynamic Properties of Silicon and Essential Doping Elements (Al, As, B, Bi, Ga, In, N, P, Sb and Tl).

    Science.gov (United States)

    Mostafa, Ahmad; Medraj, Mamoun

    2017-06-20

    Fabrication of solar and electronic silicon wafers involves direct contact between solid, liquid and gas phases at near equilibrium conditions. Understanding of the phase diagrams and thermochemical properties of the Si-dopant binary systems is essential for providing processing conditions and for understanding the phase formation and transformation. In this work, ten Si-based binary phase diagrams, including Si with group IIIA elements (Al, B, Ga, In and Tl) and with group VA elements (As, Bi, N, P and Sb), have been reviewed. Each of these systems has been critically discussed on both aspects of phase diagram and thermodynamic properties. The available experimental data and thermodynamic parameters in the literature have been summarized and assessed thoroughly to provide consistent understanding of each system. Some systems were re-calculated to obtain a combination of the best evaluated phase diagram and a set of optimized thermodynamic parameters. As doping levels of solar and electronic silicon are of high technological importance, diffusion data has been presented to serve as a useful reference on the properties, behavior and quantities of metal impurities in silicon. This paper is meant to bridge the theoretical understanding of phase diagrams with the research and development of solar-grade silicon production, relying on the available information in the literature and our own analysis.

  17. Confined-path interference suppressed quantum correction on weak antilocalization effect in a BiSbTeSe2 topological insulator

    Science.gov (United States)

    Qin, Lai-Xiang; Pan, Xin-Chen; Song, Feng-Qi; Zhang, Liang; Sun, Zhang-Hao; Li, Ming-Qiang; Gao, Peng; Lin, Ben-Chuan; Huang, Shiu-Ming; Zhu, Rui; Xu, Jun; Lin, Fang; Lu, Hai-Zhou; Yu, Dapeng; Liao, Zhi-Min

    2018-01-01

    We have studied the magnetoconductance in a topological insulator BiSbTeSe2 with different probe lengths. The magnetoconductance correction reduces by a factor of 2 when the probe length is comparable to the phase coherence length, Lφ, and the related weak antilocalization prefactor, α, reduces by a factor of 2. Lφ is independent of the probe length and follows the T-0.5, corresponding to the two-dimensional electron-electron interaction. α shows similar back-gate voltage dependence and Lφ is almost the same in both short and long channels. This indicates that the widely reported surface-to-bulk coupling is not the dominant mechanism of the α reduction. Moreover, non-saturating magnetoresistances are observed and coincided with each other in the short and long channels. The reduced α is deemed to be due to the quantum correction effect caused by the geometries and electrode distribution. The finding here will further the understanding of the transport properties of the topological insulators and unveil exotic quantum phenomena.

  18. Energy Trapping Characteristics of Bismuth Layer Structured Compound CaBi4Ti4O15

    Science.gov (United States)

    Kimura, Masahiko; Sawada, Takuya; Ando, Akira; Sakabe, Yukio

    1999-09-01

    Piezoelectric characteristics of bismuth layer structured compound CaBi4Ti4O15 ceramics were studied in terms of the energy trapping phenomenon of the second harmonic thickness extensional (TE2) vibration mode. An electrode-buried-type resonator was prepared by the co-firing technique to generate the TE2 mode, and frequency-lowering-type energy trapping was realized. Favorable resonant characteristics were obtained for piezoelectric filter and oscillator applications with narrow frequency tolerances, which require a small electromechanical coupling coefficient and a high mechanical quality factor. The electromechanical coupling coefficient for the TE2 vibration mode of the resonator was 13.9% and the mechanical quality factor Qm was 2560. The temperature coefficient of the resonance frequency was adequate for the applications. The microstructure of CaBi4Ti4O15 ceramic was also investigated. Marked shape anisotropy of the grain was observed; however, preferential grain orientation was not recognized when the ceramic was prepared by the ordinary firing process.

  19. Electromigration Critical Product to Measure Effect of Underfill Material in Suppressing Bi Segregation in Sn-58Bi Solder

    Science.gov (United States)

    Zhao, Xu; Takaya, Satoshi; Muraoka, Mikio

    2017-08-01

    Recently, we detected length-dependent electromigration (EM) behavior in Sn-58Bi (SB) solder and revealed the existence of Bi back-flow, which retards EM-induced Bi segregation and is dependent on solder length. The cause of the back-flow is attributed to an oxide layer formed on the SB solder. At present, underfill (UF) material is commonly used in flip-chip packaging as filler between chip and substrate to surround solder bumps. In this study, we quantitatively investigated the effect of UF material as a passivation layer on EM in SB solder strips. EM tests on SB solder strips with length of 50 μm, 100 μm, and 150 μm were conducted simultaneously. Some samples were coated with commercial thermosetting epoxy UF material, which acted as a passivation layer on the Cu-SB-Cu interconnections. The value of the critical product for SB solder was estimated to be 38 A/cm to 43 A/cm at 353 K to 373 K without UF coating and 59 A/cm at 373 K with UF coating. The UF material acting as a passivation layer suppressed EM-induced Bi segregation and increased the threshold current density by 37% to 55%. However, at very high current density, this effect became very slight. In addition, Bi atoms can diffuse to the anode side through the Sn phase, hence addition of microelements to the Sn phase to form obstacles, such as intermetallic compounds, may retard Bi segregation in SB solder.

  20. Creating Binary Cu–Bi Compounds via High-Pressure Synthesis: A Combined Experimental and Theoretical Study

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, Samantha M.; Amsler, Maximilian; Walsh, James P.S.; Yu, Tony; Wang, Yanbin; Meng, Yue; Jacobsen, Steven D.; Wolverton, Chris; Freedman, Danna E. (UC); (CIW); (NWU)

    2017-06-13

    Exploration beyond the known phase space of thermodynamically stable compounds into the realm of metastable materials is a frontier of materials chemistry. The application of high pressure in experiment and theory provides a powerful vector by which to explore this uncharted phase space, allowing discovery of complex new structures and bonding in the solid state. We harnessed this approach for the Cu–Bi system, where the realization of new phases offers potential for exotic properties such as superconductivity. This potential is due to the presence of bismuth, which, by virtue of its status as one of the heaviest stable elements, forms a critical component in emergent materials such as superconductors and topological insulators. To fully investigate and understand the Cu–Bi system, we welded theoretical predictions with experiment to probe the Cu–Bi system under high pressures. By employing the powerful approach of in situ X-ray diffraction in a laser-heated diamond anvil cell (LHDAC), we thoroughly explored the high-pressure and high-temperature (high-PT) phase space to gain insight into the formation of intermetallic compounds at these conditions. We employed density functional theory (DFT) calculations to calculate a pressure versus temperature phase diagram, which correctly predicts that CuBi is stabilized at lower pressures than Cu11Bi7, and allows us to uncover the thermodynamic contributions responsible for the stability of each phase. Detailed comparisons between the NiAs structure type and the two high-pressure Cu–Bi phases, Cu11Bi7 and CuBi, reveal the preference for elemental segregation within the Cu–Bi phases, and highlight the unique channels and layers formed by ordered Cu vacancies. The electron localization function from DFT calculations account for the presence of these “voids” as a manifestation of the lone pair orientation on the Bi atoms. Our study demonstrates the power of joint experimental–computational work in exploring the

  1. The Effect of SbI3 Doping on the Structure and Electrical Properties of n-Type Bi1.8Sb0.2Te2.85Se0.15 Alloy Prepared by the Free Growth Method

    Science.gov (United States)

    Wang, Xiaoyu; Yu, Yuan; Zhu, Bin; Gao, Na; Huang, Zhongyue; Xiang, Bo; Zu, Fangqiu

    2017-11-01

    Thermoelectric technology is regarded as one of the most promising direct power generation techniques via thermoelectric materials. However, the batch production and scale-up application are hindered because of the high-cost and poor performance. In this work, we adopt the free growth method to synthesize a series of the bulk materials of SbI3-doped Bi1.8Sb0.2Te2.85Se0.15 alloys. The structural and component investigations as well as the electrical properties characterization are carried out. The results show that SbI3 promotes the formation of Te-rich regions in the matrix. In addition, the synergistically optimized electrical conductivity and Seebeck coefficient are attained by controlling the SbI3 doping concentration. Thus, the sample with 0.30 wt.% SbI3 displays a highly increased power factor of ˜ 13.57 μW cm-1 K-2, which is nearly 21 times higher than that of the undoped one. Moreover, the free growth method is reproducible, convenient and economical. Therefore, it has great potential as a promising technology for the batch synthesis.

  2. Thermodynamic data for the speciation and solubility of Pd, Pb, Sn, Sb, Nb and Bi in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Lothenbach, B.; Ochs, M. [BMG Engineering Ltd., Zuerich-Schlieren (Switzerland); Wanner, H.; Yui, Mikazu

    1999-01-01

    This report provides thermodynamic data for predicting concentrations of palladium, lead, tin, antimony, niobium and bismuth in geologic environments, and contributes to an integration of the JNC chemical thermodynamic database, JNC-TDB (previously PNC-TDB), for the performance analysis of geological isolation system of high-level radioactive wastes. Besides treating hydrolysis in detail, this report focuses on the formation of complexes or compounds with chloride, fluoride, carbonate, nitrate, sulfate and phosphate. Other important inorganic ligands (sulfide for lead and antimony, ammonia for palladium) are also included. In this study, the specific ion interaction theory (SIT) approach is used to extrapolate thermodynamic constants to zero ionic strength at 25degC. (author)

  3. Thermoelectric Properties of Ag-Doped Bi2(Se,Te)3 Compounds: Dual Electronic Nature of Ag-Related Lattice Defects.

    Science.gov (United States)

    Lu, Meng-Pei; Liao, Chien-Neng; Huang, Jing-Yi; Hsu, Hung-Chang

    2015-08-03

    Effects of Ag doping and thermal annealing temperature on thermoelectric transport properties of Bi2(Se,Te)3 compounds are investigated. On the basis of the comprehensive analysis of carrier concentration, Hall mobility, and lattice parameter, we identified two Ag-related interstitial (Agi) and substitutional (AgBi) defects that modulate in different ways the thermoelectric properties of Ag-doped Bi2(Se,Te)3 compounds. When Ag content is less than 0.5 wt %, Agi plays an important role in stabilizing crystal structure and suppressing the formation of donor-like Te vacancy (VTe) defects, leading to the decrease in carrier concentration with increasing Ag content. For the heavily doped Bi2(Se,Te)3 compounds (>0.5 wt % Ag), the increasing concentration of AgBi is held responsible for the increase of electron concentration because formation of AgBi defects is accompanied by annihilation of hole carriers. The analysis of Seebeck coefficients and temperature-dependent electrical properties suggests that electrons in Ag-doped Bi2(Se,Te)3 compounds are subject to a mixed mode of impurity scattering and lattice scattering. A 10% enhancement of thermoelectric figure-of-merit at room temperature was achieved for 1 wt % Ag-doped Bi2(Se,Te)3 as compared to pristine Bi2(Se,Te)3.

  4. Effects of Ni and carbon-coated Ni addition on the thermoelectric properties of 25Bi{sub 2}Te{sub 3}+75Sb{sub 2}Te{sub 3} base composites

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sang Min; Dharmaiah, Peyala; Femi, Olu Emmanuel; Lee, Chul Hee; Hong, Soon-Jik, E-mail: hongsj@kongju.ac.kr

    2017-07-01

    In this paper, we report the effect of nickel (Ni) and carbon coated nickel (C-Ni) on the thermoelectric and mechanical properties of 25Bi{sub 2}Te{sub 3}+75Sb{sub 2}Te{sub 3} (GA) base composites. Ni and C-Ni powders were synthesized using pulse wire evaporation and mixed with 25Bi{sub 2}Te{sub 3}+75Sb{sub 2}Te{sub 3} in a planetary ball mill. The morphology of the Ni and C-Ni powders and GA + x (x = none, Ni, or C-Ni) composites were examined using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The thermoelectric properties of the GA + x (x = none, Ni, or C-Ni) composites shows that the addition of Ni increases the carrier concentration while the presence of C-Ni reduces the carrier concentration to a level comparable to the bare sample (x = 0). Subsequently, the Seebeck coefficient of the GA + C-Ni sample increases by about 18% more than in the bare sample. The thermal conductivity of the GA + Ni and GA + C-Ni samples was considerably lower at room temperature compared to the bare sample. The mechanical properties of the GA + Ni and GA + C-Ni composite samples show a three-fold improvement compared to the bare sample. - Highlights: • Ni and carbon-coated Ni nanoparticles were incorporated into 25Bi{sub 2}Te{sub 3}+75Sb{sub 2}Te{sub 3} (BST) matrix. • Seebeck coefficient increased by 18% for BST/carbon coated Ni composites. • BST/carbon coated Ni composite reduces the thermal conductivity (21%). • The Vickers hardness of the BST/C-Ni composite samples significantly improved.

  5. The Shubnikov-de Haas effect and thermoelectric properties of Tl-doped Sb{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kulbachinskii, V. A., E-mail: kulb@mig.phys.msu.ru; Kudryashov, A. A.; Kytin, V. G. [Moscow State University, Faculty of Physics (Russian Federation)

    2015-06-15

    The influence of doping with Tl on the Shubnikov-de Haas effect at T = 4.2 K in magnetic fields up to 38 T in p-Sb{sub 2−x}Tl{sub x}Te{sub 3} (x = 0, 0.005, 0.015, and 0.05) and n-Bi{sub 2−x}Tl{sub x}Se{sub 3} (x = 0, 0.01, 0.02, 0.04, and 0.06) single crystals is investigated. Extreme cross-sections of the Fermi surface in both materials decrease upon doping with Tl: the hole concentration decreases in Sb{sub 2−x}Tl{sub x}Te{sub 3} due to the donor effect of Tl and the electron concentration in n-Bi{sub 2−x}Tl{sub x}Se{sub 3} decreases due to the acceptor effect of Tl. The temperature dependences of the Seebeck coefficient, electrical conductivity, thermal conductivity, and dimensionless thermoelectric figure of merit in a temperature range of 77–300 K are measured. The thermal conductivity and electrical conductivity decrease upon doping with Tl both in p-Sb{sub 2−x}Tl{sub x}Te{sub 3} and in n-Bi{sub 2−x}Tl{sub x}Se{sub 3}. The Seebeck coefficient increases in all compositions upon an increase in doping over the entire measured temperature range. The thermoelectric figure of merit increases upon doping with Tl.

  6. Synthesis and characterization of (1-x)Bi(Mg{sub 2/3}Sb{sub 1/3})O{sub 3}-xPbTiO{sub 3} piezoceramics

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Ashutosh; Dwivedi, Saurabh; Pandey, Rishikesh; Singh, Akhilesh Kumar, E-mail: akhilesh-bhu@yahoo.com [School of Materials Science & Technology, Indian Institute of Technology, Banaras Hindu University, Varanasi-221005 (India)

    2016-05-23

    We present here the comprehensive x-ray diffraction and polarization-electric field hysteresis studies on (1-x)Bi(Mg{sub 2/3}Sb{sub 1/3})O{sub 3}-xPbTiO{sub 3} piezoceramics with x = 0.52, 0.56 and 0.60. The powder x-ray diffraction data reveals the presence of tetragonal phase for all the compositions. The saturation of hysteresis loop is observed for x ≤ 0.56.

  7. Synthesis, magnetic properties and Moessbauer spectroscopy for the pyrochlore family Bi{sub 2}BB Prime O{sub 7} with B=Cr and Fe and B Prime =Nb, Ta and Sb

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Maria C. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Franco, Diego G. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Centro Atomico Bariloche - CNEA, Av. E. Bustillo 9500, S.C. de Bariloche (8500), R.N. (Argentina); Jalit, Yamile; Pannunzio Miner, Elisa V. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Berndt, Graciele; Paesano, Andrea [Departamento de Fisica, Universidade Estadual de Maringa, Parana (Brazil); Nieva, Gladys [Centro Atomico Bariloche - CNEA, Av. E. Bustillo 9500, S.C. de Bariloche (8500), R.N. (Argentina); Carbonio, Raul E., E-mail: carbonio@mail.fcq.unc.edu.ar [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina)

    2012-08-15

    The samples Bi{sub 2}BB Prime O{sub 7}, with B=Cr and Fe and B Prime =Nb, Ta and Sb were prepared by solid state method. The crystallographic structure was investigated on the basis of X-ray powder diffraction data. Rietveld refinements show that the crystal structure is cubic, space group Fd-3m. The Bi{sup 3+} cation on the eight-coordinate pyrochlore A-site shows displacive disorder, as a consequence of its lone pair electron configuration. There is also a considerable A-site disorder shown by Rietveld Analysis and confirmed in the case of the iron containing samples with Moessbauer spectroscopy. The magnetic measurements show paramagnetic behavior at all temperatures for the Cr oxides. The Fe pyrochlores show antiferromagnetic order around 10 K.

  8. A subgroup of plant aquaporins facilitate the bi-directional diffusion of As(OH3 and Sb(OH3 across membranes

    Directory of Open Access Journals (Sweden)

    Wagner Annemarie

    2008-06-01

    Full Text Available Abstract Background Arsenic is a toxic and highly abundant metalloid that endangers human health through drinking water and the food chain. The most common forms of arsenic in the environment are arsenate (As(V and arsenite (As(III. As(V is a non-functional phosphate analog that enters the food chain via plant phosphate transporters. Inside cells, As(V becomes reduced to As(III for subsequent extrusion or compartmentation. Although much is known about As(III transport and handling in microbes and mammals, the transport systems for As(III have not yet been characterized in plants. Results Here we show that the Nodulin26-like Intrinsic Proteins (NIPs AtNIP5;1 and AtNIP6;1 from Arabidopsis thaliana, OsNIP2;1 and OsNIP3;2 from Oryza sativa, and LjNIP5;1 and LjNIP6;1 from Lotus japonicus are bi-directional As(III channels. Expression of these NIPs sensitized yeast cells to As(III and antimonite (Sb(III, and direct transport assays confirmed their ability to facilitate As(III transport across cell membranes. On medium containing As(V, expression of the same NIPs improved yeast growth, probably due to increased As(III efflux. Our data furthermore provide evidence that NIPs can discriminate between highly similar substrates and that they may have differential preferences in the direction of transport. A subgroup of As(III permeable channels that group together in a phylogenetic tree required N-terminal truncation for functional expression in yeast. Conclusion This is the first molecular identification of plant As(III transport systems and we propose that metalloid transport through NIPs is a conserved and ancient feature. Our observations are potentially of great importance for improved remediation and tolerance of plants, and may provide a key to the development of low arsenic crops for food production.

  9. Effect of deformation on the electronic structure and topological properties of the AIIMg2Bi2 (AII = Mg,Ca,Sr,Ba) compounds

    Science.gov (United States)

    Petrov, E. K.; Silkin, I. V.; Koroteev, Yu. M.; Chulkov, E. V.

    2017-04-01

    The electronic structure and topological properties of the AIIMg2Bi2 (AII = Mg,Ca,Sr,Ba) compounds are theoretically studied with the use of exact exchange. It is found that the Mg3Bi2 compound in the equilibrium state is a semimetal, whereas three other compounds are semiconductors with a direct fundamental band gap. It is predicted that the uniaxial deformation of three-component compounds results in transitions to topologically nontrivial phases: topological insulator and topological and Dirac semimetals. Owing to such a rich variety of topologically nontrivial phases, these compounds may be of interest for further theoretical and experimental studies.

  10. Study of structural and dimensional characteristics of the melt spun p-Bi0.5Sb1.5Te3 powders compacted by vacuum hot pressing and spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Andrei A. Melnikov

    2015-12-01

    Full Text Available P-type thermoelectric Bi0,5Sb1,5Te3 powders were obtained by the melt spinning technique (extremely rapid quenching from the liquid state and their structural and dimensional characteristics were characterized. The crystallographic group and the lattice parameters of the powders correspond to those for Bi0,5Sb1,5Te3 crystallized in equilibrium conditions which suggests the identity of the crystal structure. The powders were compacted by vacuum hot pressing and spark plasma sintering. We found that the partial axial texture [001] directed along the axis of pressure application could be formed during the compacting of the powders. Temperature dependences of the thermoelectric characteristics of the compacted material were measured in a direction perpendicular to the pressure application axis in the 100–700 K range. It is demonstrated that the compacted samples possess low thermal conductivity while retaining the Seebeck coefficient and the electrical conductivity values comparable to crystallized material; therefore ZT reaches 1.05–1.15 in the 330–350 K range which indicates high prospects of applying these technologies.

  11. Enhanced thermoelectric properties in p-type Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} alloy by combining incorporation and doping using multi-scale CuAlO{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Song, Zijun; Liu, Yuan; Zhou, Zhenxing; Lu, Xiaofang; Wang, Lianjun [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai (China); Institute of Functional Materials, Donghua University, Shanghai (China); Zhang, Qihao [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China); University of Chinese Academy of Sciences, Beijing (China); Jiang, Wan [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai (China); Institute of Functional Materials, Donghua University, Shanghai (China); School of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen (China); Chen, Lidong [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China)

    2017-01-15

    Multi-scale CuAlO{sub 2} particles are introduced into the Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} matrix to synergistically optimize the electrical conductivity, Seebeck coefficient, and the lattice thermal conductivity. Cu element originating from fine CuAlO{sub 2} grains diffuses into the Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} matrix and tunes the carrier concentration while the coarse CuAlO{sub 2} particles survive as the second phase within the matrix. The power factor is improved at the whole temperatures range due to the low-energy electron filtering effect on Seebeck coefficient and enhanced electrical transport property by mild Cu doping. Meanwhile, the remaining CuAlO{sub 2} inclusions give rise to more boundaries and newly built interfaces scattering of heat-carrying phonons, resulting in the reduced lattice thermal conductivity. Consequently, the maximum ZT is found to be enhanced by 150% arising from the multi-scale microstructure regulation when the CuAlO{sub 2} content reaches 0.6 vol.%. Not only that, but the ZT curves get flat in the whole temperature range after introducing the multi-scale CuAlO{sub 2} particles, which leads to a remarkable increase in the average ZT. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Nuclear Quadrupole Resonance Measurement of the Ferromagnetic Filled-Skutterudite Compound EuRu4Sb12

    Science.gov (United States)

    Koyama, Takehide; Maeda, Yoshitaka; Ueda, Koichi; Mito, Takeshi; Sugawara, Hitoshi

    2015-08-01

    We report the detailed analysis of the 101Ru nuclear quadrupolar resonance spectrum in the ferromagnetically ordered state of EuRu4Sb121 and propose that Eu 4f moments align in the [111] direction. The localized character of Eu 4f electrons is suggested from the temperature dependence of the nuclear spin-lattice relaxation rate.

  13. From racemic compound to spontaneous resolution: A series of homochiral lanthanide coordination polymers constructed from presynthesized [Sb2(tart)2]2- metalloligands

    Science.gov (United States)

    He, Jianghong; Zhang, Guangju; Xiao, Dongrong; Chen, Haiyan; Yan, Shiwei; Wang, Xin; Yang, Juan; Yuan, Ruo; Wang, Enbo

    2012-06-01

    A series of homochiral 1D lanthanide coordination polymers, namely {Ln(H2O)5(NO3)[Sb2(D-tart)2]}·H2O (Ln = Ce (1), Eu (5)) and {Ln(H2O)5(NO3)[Sb2(L-tart)2]}·H2O (Ln = Pr (2), Nd (3), Sm (4), Dy (6)) (tart = tartaric acid) were obtained by spontaneous resolution from presynthesized racemic [Sb2(tart)2]2- metalloligands (MLs). Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, X-ray powder diffraction, and TG analyses. Compounds 1-6 are isostructural and feature novel 1D homochiral chains. There are three types of hydrogen-bonded helices in the 3D supramolecular network of 1-6. This case is still rare in metal-organic complexes. In addition, the luminescent properties of 4-6 were studied in the solid state at room temperature.

  14. Dielectric and Impedance Characteristics of Nickel-Modified BiFeO3-BaTiO3 Electronic Compound

    Science.gov (United States)

    Das, S. N.; Pardhan, S. K.; Bhuyan, S.; Sahoo, S.; Choudhary, R. N. P.; Goswami, M. N.

    2018-01-01

    The temperature- and field-dependent capacitive, resistive and conducting characteristics of nickel-modified binary electronic systems of bismuth ferrite (BiFeO3) and barium titanate (BaTiO3) have been investigated using dielectric and impedance spectroscopy techniques. The orthorhombic crystal structures of the solid solution (Bi1-2xNixBax)(Fe1-2xTi0.2x)O3 (with x = 0.10, 0.15, 0.20 and 0.25) have been identified from powder x-ray crystallography. The micrographs exhibit the development of dense samples with reduced grain size for higher percentage of Ni in the BiFeO3-BaTiO3. The stoichiometric content of each sample has been realized using the energy dispersive x-ray technique. The relationship between micro-structural study and frequency-temperature-dependent electrical properties of the compound has revealed a negative temperature coefficient of resistance behavior. A non-Debye-type relaxation process is observed from the Niquist plot. The studied compound presents important dielectric properties for the formulation of electronic devices.

  15. Control microestructural en varistores cerámicos basados en el sistema ZnO-Bi2O3-Sb2O3 dopados con TiO2

    Directory of Open Access Journals (Sweden)

    Fernández-Hevia, D.

    2012-02-01

    Full Text Available Typically Titanium oxide is added to the formulation of Bi2O3-doped ZnO based varistors to enhance the growth of ZnO grains, thus allowing their application in low voltage devices. However its incorporation to formulation based on the ZnOBi2O3-Sb2O3 (ZBS system, characteristic of high voltage applications has not been analyzed jet. In this contribution it has been verified that far from promoting the ZnO grain growth, the incorporation of TiO2 to varistor formulations based on this ZBS ternary system leads to a better control of the varistor microstructure, which in turns causes an appreciable improvement of its electrical response.Típicamente el Óxido de Titanio se incorpora a la formulación de varistores basados en ZnO dopado con Bi2O3 para favorecer un crecimiento de los granos de ZnO, lo que determina su aplicación en dispositivos de bajo voltaje. Sin embargo su incorporación en formulaciones basadas en el ternario ZnO-Bi2O3-Sb2O3 (sistema ZBS, características de aplicaciones de alto voltaje, es algo que apenas se ha analizado. En este trabajo se ha comprobado que lejos de favorecer el crecimiento de los granos de ZnO, la incorporación de TiO2 a sistemas basados en dicho ternario ZBS lleva a un mayor control de la microestructura de estos electrocerámicos, y esto además se traduce en una apreciable mejoría de su respuesta eléctrica.

  16. Electronic structure and superconducting behaviour of LuPtBi half-Heusler compound: A first principle study

    Science.gov (United States)

    Shrivastava, Deepika; Sanyal, Sankar P.

    2018-01-01

    The electronic, phonon and superconducting properties of LuPtBi half-Heusler compound in MgAgAs-type cubic structure have been studied by using first principles density functional theory and linear response technique. Electronic and bonding properties have been analysed from electronic band structure, density of states, Fermi surfaces and charge density plot. Positive phonon frequencies confirm the stability of LuPtBi in cubic MgAgAs phase. Superconducting transition temperature (TC) is calculated using Eliashberg spectral function (α2F(ω)). For calculation of TC we have used screened Coulomb repulsion constant (μ*) as 0.15 and found TC = 1.1 K, which agree well with the experimental value (TC = 1.0 K). About 10% error in TC from its experimental value is observed for μ* = 0.15 which increases by 40% when the value of μ* = 0.13 (TC = 1.4 K).

  17. Molecular beam epitaxial growth of layered Bi-Sr-Ca-Cu-O compounds

    Science.gov (United States)

    Schlom, D. G.; Marshall, A. F.; Sizemore, J. T.; Chen, Z. J.; Eckstein, J. N.

    1990-05-01

    The in situ epitaxial growth of Bi-Sr-Ca-Cu-O films by molecular beam epitaxy (MBE) is reported. The suitability of various oxidants for the MBE growth of cuprate superconductors is discussed, and the use of ozone described. Molecular beams of the constituents were periodically shuttered to grow various Bi2Sr2Ca(n-1)Cu(n)O(x) phases, including 2201, 2212, 2223, 2245, and layered 2212/2223 and 2223/2234 mixtures. Some of the films grown in this way were superconducting as grown. The ability of MBE to grow layered, probably metastable Bi2Sr2Ca(n-1)Cu(n)O(x) films is demonstrated.

  18. Coexistence of monochalocogen and dichalocogen ions in BiSe2 and BiS2 crystals prepared at high pressure.

    Science.gov (United States)

    Yamamoto, Ayako; Hashizume, Daisuke; Bahramy, Mohammad Saeed; Tokura, Yoshinori

    2015-04-20

    A single crystal of bismuth diselenide, BiSe2, containing both monochalcogen (Se(2-)) and dichalcogen (Se2(2-)) ions, was prepared at a high pressure of 5.5 GPa. Its crystal structure, substitution chemistry, and physical properties were investigated. X-ray analysis showed that BiSe2 is in a monoclinic system (space group C2/m) with the following lattice parameters: a = 16.740(3) Å, b = 4.1410(11) Å, c = 12.027(3) Å, and β = 127.658(13)°. A crystal structure of BiSe2 can be viewed as a layered structure with stacks of neutral BiSe2 blocks along the c-axis, or alternatively as a quasi-one-dimensional structure with double chains of BiSe5 pyramids along the b-axis. Each Bi is coordinated with three Se(2-) ions and two Se2(2-) ions, and the bond valence analysis indicated that Bi was trivalent. BiSe2 and BiS2 form a solid solution in the whole range while retaining the same structure, and the partial substitution of Sb for Bi is also achieved at 10%. All the compounds show a semiconducting property and diamagnetism that can be attributed to the closed-shell ion core. In spite of the compositional analogy with Bi2Se3, BiSe2 is proven by the first-principles calculations not to be a topological insulator.

  19. Structural phase transitions of (Bi1-xSbx)2(Te1-ySey)3 compounds under high pressure and the influence of the atomic radius on the compression processes of tetradymites.

    Science.gov (United States)

    Zhao, Jinggeng; Yu, Zhenhai; Hu, Qingyang; Wang, Yong; Schneeloch, John; Li, Chunyu; Zhong, Ruidan; Wang, Yi; Liu, Zhiguo; Gu, Genda

    2017-01-18

    Recently, A2B3-type tetradymites have developed into a hot topic in physical and material research fields, where the A and B atoms represent V and VI group elements, respectively. In this study, in situ angle-dispersive X-ray diffraction measurements were performed on Bi2Te2Se, BiSbTeSe2, and Sb2Te2Se tetradymites under high pressure. Bi2Te2Se transforms from a layered rhombohedral structure (phase I) into 7-fold monoclinic (phase II) and body-centered tetragonal (phase IV) structures at about 8.0 and 14.3 GPa, respectively, without an 8-fold monoclinic structure (phase III) similar to that in Bi2Te3. Thus, the compression behavior of Bi2Te2Se is the same as that of Bi2Se3, which could also be obtained from first-principles calculations and in situ high-pressure electrical resistance measurements. Under high pressure, BiSbTeSe2 and Sb2Te2Se undergo similar structural phase transitions to Bi2Te2Se, which indicates that the compression process of tellurides can be modulated by doping Se in Te sites. According to these high-pressure investigations of A2B3-type tetradymites, the decrease of the B-site atomic radius shrinks the stable pressure range of phase III and expands that of phase II, whereas the decrease of the A-site atomic radius induces a different effect, i.e. expanding the stable pressure range of phase III and shrinking that of phase II. The influence of the atomic radius on the compression process of tetradymites is closely related to the chemical composition and the atom arrangement in the quintuple layer.

  20. Speciation analysis of Sb(III) and Sb(V) in antileishmaniotic drug using Dowex 1 x 4 resin from hydrochloric acid solution.

    Science.gov (United States)

    Łukaszczyk, L; Zyrnicki, W

    2010-09-05

    A new and simple method for the direct and simultaneous determination of Sb(III) and Sb(V) in meglumine antimoniate, the first-choice drug for leishmaniasis treatment, was developed. Speciation analysis was carried out using the quantitative separation of inorganic trivalent and pentavalent antimony on Dowex 1 x 4 resin from 1.5 mol l(-1) hydrochloric acid solution. The inductively coupled plasma optical emission spectrometry (ICP-OES) was used for determination of antimony. The interfering effects of As, Bi, Cd, Cu, Mn, Pb and Zn were examined and only Bi was found to be a significant interferent. The liberation of Sb(V) and Sb(III) from organoantimonial compounds without changing of oxidation state was carried out by means of 1.5 mol l(-1) hydrochloric acid solution. The spike recovery values obtained for Sb(III) in pharmaceutical sample varied from 92 to 100%. The method was successfully applied for the direct determination of antimony(III) and of antimony(V) in meglumine antimoniate. 2010 Elsevier B.V. All rights reserved.

  1. High-Pressure Synthesis, Structure, and Magnetic Properties of Ge-Substituted Filled Skutterudite Compounds; LnxCo4Sb12−yGey, Ln = La, Ce, Pr, and Nd

    Directory of Open Access Journals (Sweden)

    Hiroshi Fukuoka

    2017-12-01

    Full Text Available A series of new Ge-substituted skutterudite compounds with the general composition of LnxCo4Sb12−yGey, where Ln = La, Ce, Pr, and Nd, is prepared by high-pressure and high-temperature reactions at 7 GPa and 800 °C. They have a cubic unit cell and the lattice constant for each compound is 8.9504 (3, 8.94481 (6, 8.9458 (3, and 8.9509 (4 Å for the La, Ce, Pr, and Nd derivatives, respectively. Their chemical compositions, determined by electron prove microanalysis, are La0.57Co4Sb10.1Ge2.38, Ce0.99Co4Sb9.65Ge2.51, Pr0.97Co4Sb9.52Ge2.61, and Nd0.87Co4Sb9.94Ge2.28. Their structural parameters are refined by Rietveld analysis. The guest atom size does not affect the unit cell volume. The Co–Sb/Ge distance mainly determines the unit cell size as well as the size of guest atom site. The valence state of lanthanide ions is 3+.

  2. Simultaneous determination of Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe in water samples by differential pulse stripping voltammetry at a hanging mercury drop electrode.

    Science.gov (United States)

    Ghoneim, M M; Hassanein, A M; Hammam, E; Beltagi, A M

    2000-06-01

    A highly sensitive and selective voltammetric procedure is described for the simultaneous determination of eleven elements (Cd, Pb, Cu, Sb, Bi, Se, Zn, Mn, Ni, Co and Fe) in water samples. Firstly, differential pulse anodic stripping voltammetry (DPASV) with a hanging mercury drop electrode (HMDE) is used for the direct simultaneous determination of Cd, Pb, Cu, Sb and Bi in 0.1 M HCI solution (pH = 1) containing 2 M NaCl. Then, differential pulse cathodic stripping voltammetry (DPCSV) is used for the determination of Se in the same solution. Zn is subsequently determined by DPASV after raising the pH of the same solution to pH 4. Next, the pH of the medium is raised to pH 8.5 by adding NH3/NH4Cl buffer solution for the determination of Mn by DPASV. Ni and Co are determined in the same solution by differential pulse adsorptive stripping voltammetry (DPAdSV) after adding DMG (1 x 10(-4) M). Finally, 1 x 10(-5) M 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) is added to the solution for the determination of Fe by DPAdSV. The optimal conditions are described. Relative standard deviations and relative errors are calculated for the eleven elements at three different concentration levels. The lower detection limits for the investigated elements range from 1.11 x 10(-10) to 1.05 x 10(-9)M, depending on the element determined. The proposed analysis scheme was applied for the determination of these eleven elements in some ground water samples.

  3. Control of microstructure in TiO{sub 2}-doped ceramic varistors based in the ZnO-Bi{sub 2}O{sub 3}-Sb{sub 2}O{sub 3} system; Control microestructural en varistores ceramicos basados en el sistema ZnO-Bi{sub 2}O{sub 3}-Sb{sub 2}O{sub 3} dopados con TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, A. M.; Reyes, Y.; Gallego, B.; Fernandez-Hevia, D.; Peiteado, M.

    2012-07-01

    Typically Titanium oxide is added to the formulation of Bi{sub 2}O{sub 3}-doped ZnO based varistors to enhance the growth of ZnO grains, thus allowing their application in low voltage devices. However its incorporation to formulation based on the ZnOBi {sub 2}O{sub 3}-Sb{sub 2}O{sub 3} (ZBS system), characteristic of high voltage applications has not been analyzed jet. In this contribution it has been verified that far from promoting the ZnO grain growth, the incorporation of TiO{sub 2} to varistor formulations based on this ZBS ternary system leads to a better control of the varistor microstructure, which in turns causes an appreciable improvement of its electrical response. (Author)

  4. The electronic and thermoelectric properties of a d2/d0 type tetragonal half-Heusler compound, HfSiSb: a FP-LAPW method

    Science.gov (United States)

    Joshi, H.; Rai, D. P.; Deligoz, E.; Ozisik, H. B.; Thapa, R. K.

    2017-10-01

    We present an implementation of the full-potential linearized augmented plane-wave method for carrying out ab initio calculations of the electronic and thermoelectric properties of d2/d0 type HfSiSb based on the density-functional theory. A most common generalized gradient approximation is taken into consideration for exchange-correlation energy. The electronic calculations show that HfSiSb is metallic in nature because of the overlap between the valence band and the conduction band. The thermoelectric properties, such as Seebeck coefficient, electronic thermal conductivity and electrical conductivity were calculated along the perpendicular and parallel directions with respect to chemical potential (µ) and temperature. In addition, we also included lattice thermal conductivity ({{κ }p} ) to obtain the total thermal conductivity. The presence of total thermal conductivity gave us an exact understanding of the material’s thermodynamics and its efficiency (ZT). A sharp variation in ZT in the range (200–400 K) was seen, which makes this compound suitable at around room temperature.

  5. Thickness dependence of electrical conductivity and thermo-electric power of Bi2.0Te2.7Se0.3/Bi0.4Te3.0Sb1.6 thermo-electric devices

    Science.gov (United States)

    Liao, M.-H.; Huang, K.-C.; Tsai, F.-A.; Liu, C.-Y.; Lien, C.; Lee, M.-H.

    2018-01-01

    The electrical and thermo-electric (TE) properties of the bismuth telluride (BiTe) -based two-dimensional (2D) thermoelectric (TE) devices with different thin film thicknesses are analyzed systematically. The studied thin film thicknesses are covered from 100 nm to 400 nm. The accurate measured systems for the Seebeck coefficient (S) and electrical conductivity (σ) extractions are also built up in this work. When the thickness of the BiTe-based thin film in the TE device is scaled from 400 nm to 100 nm, the occurred optimized temperature (T) for the highest S value in these devices is found to be shifted from 60°C to 100°C. On the other hand, the best σ is observed in the thinner (100 nm) BiTe-based thin film devices under the higher T (130°C). Based on the understanding of S and σ values, the power factor and the figure of merit (ZT) - i.e., the ability of a TE material to efficiently produce electricity - are also investigated further. Compared with the commercial bulk BiTe TE device, we demonstrate that the ZT value can be improved ˜50% with the thinner (100 nm) BiTe-based thin film devices in the higher T (>100°C) region.

  6. Superconductivity dependent on the amount of Bi and Sr in the Bi{sub 2}Sr{sub 2}CuO{sub 6} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.H. [Department of Chemistry, Tamkang University, Tamsui 251, Taiwan (China); Chu, Y.C.; Ling, D.C.; Liu, S.H.; Pong, W.F. [Department of Physics, Tamkang University, Tamsui 251, Taiwan (China); Hseu, H.S.; Chen, J.M.; Lee, J.F. [National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (China); Kao, H.-C.I. [Department of Chemistry, Tamkang University, Tamsui 251, Taiwan (China)], E-mail: kaohci@mail.tku.edu.tw

    2007-09-01

    Two series of samples with nominal compositions of Bi{sub 2+x}Sr{sub 2}CuO{sub y} and Bi{sub 2}Sr{sub 2-x}CuO{sub y} (0 {<=} x {<=} 0.10) were prepared by a conventional solid-state reaction method. Laminar morphology is observed for all the samples under SEM. EDS analysis shows that Bi is slightly volatile, the depletion amount is about 3% in the Bi rich samples, but only about 1% loses in the Sr deficient samples. Hole concentration of the Bi{sub 2}Sr{sub 2-x}CuO{sub y} series increases with increasing x, showing a hole doping effect caused by the depletion of the Sr ions. In contrary, Bi{sub 2+x}Sr{sub 2}CuO{sub y} series has a hole filling effect by introducing the extra Bi ions. These samples show metallic conducting behavior in the normal state and superconducting property at lower temperature. T{sub c} decreases with increasing x on both series. Bi{sub 2}Sr{sub 2}CuO{sub y} has the highest T{sub c} at 7.9 K with an optimal hole concentration of 0.237. Hole concentrations obtained from the O-K edge XANES spectra and the iodometric titration agree well in these samples.

  7. Dirac cone and pseudogapped density of states in the topological half-Heusler compound YPtBi

    Science.gov (United States)

    Kronenberg, A.; Braun, J.; Minár, J.; Elmers, H.-J.; Kutnyakhov, D.; Zaporozhchenko, A. V.; Wallauer, R.; Chernov, S.; Medjanik, K.; Schönhense, G.; Kläui, M.; Chadov, S.; Ebert, H.; Jourdan, M.

    2016-10-01

    Topological insulators (TIs) are exciting materials, which exhibit unprecedented properties, such as helical spin-momentum locking, which leads to large torques for magnetic switching and highly efficient spin current detection. Here we explore the compound YPtBi, an example from the class of half-Heusler materials, for which the typical band inversion of topological insulators was predicted. We prepared this material as thin films by conventional cosputtering from elementary targets. By in situ time-of-flight momentum microscopy, a Dirac conelike surface state with a Dirac point ≃300 meV below the Fermi energy was observed, in agreement with electronic structure-photoemission calculations. Only little additional spectral weight due to other states was observed at EF, which corroborates the identification of the topologically protected surface state and is highly relevant for spintronics applications.

  8. Electrodeposition of Ni on Bi2Te3 and Interfacial Reaction Between Sn and Ni-Coated Bi2Te3

    Science.gov (United States)

    Tseng, Yu-Chen; Lee, Hsuan; Hau, Nga Yu; Feng, Shien-Ping; Chen, Chih-Ming

    2018-01-01

    Bismuth-telluride (Bi2Te3)-based compounds are common thermoelectric materials used for low-temperature applications, and nickel (Ni) is usually deposited on the Bi2Te3 substrates as a diffusion barrier. Deposition of Ni on the p-type (Sb-doped) and n-type (Se-doped) Bi2Te3 substrates using electroplating and interfacial reactions between Sn and Ni-coated Bi2Te3 substrates are investigated. Electrodeposition of Ni on different Bi2Te3 substrates is characterized based on cyclic voltammetry and Tafel measurements. Microstructural characterizations of the Ni deposition and the Sn/Ni/Bi2Te3 interfacial reactions are performed using scanning electron microscopy. A faster growth rate is observed for the Ni deposition on the n-type Bi2Te3 substrate which is attributed to a lower activation energy of reduction due to a higher density of free electrons in the n-type Bi2Te3 material. The common Ni3Sn4 phase is formed at the Sn/Ni interfaces on both the p-type and n-type Bi2Te3 substrates, while the NiTe phase is formed at a faster rate at the interface between Ni and n-type Bi2Te3 substrates.

  9. Electrical and Switching Properties of TlBiSe2 Chalcogenide Compounds

    Science.gov (United States)

    Kalkan, N.; Bas, H.

    2015-11-01

    The electrical conductivity of TlBiSe2 narrow gap semiconductors prepared by the Bridgman-Stockbarger method was investigated. The temperature dependence of the electrical conductivity was measured to establish the dominant conductivity mechanism in a temperature range between 293 K and 373 K. The conduction activation energy has a single value indicating the existence of one type of conduction mechanism in the investigated temperature range. The electrical conductivity of the sample is controlled by a thermally activated mechanism. It was also found that these samples exhibit a current-controlled negative resistance and threshold switching. The value of the threshold voltage decreases exponentially with increasing temperature. The calculated ratio of the threshold energy to the activation energy is one half, and is derived from the electro-thermal model for the switching process. Therefore, the electrical switching in the investigated samples can be explained in terms of the electro-thermal model. A possible conduction mechanism in the pre-switching state of the sample associated with the space charge limited current is described.

  10. Incorporation of Sb and As in MBE grown GaAsxSb1-x layers

    Science.gov (United States)

    Zederbauer, Tobias; Andrews, Aaron Maxwell; MacFarland, Don; Detz, Hermann; Schrenk, Werner; Strasser, Gottfried

    2017-03-01

    With the increasing interest in low effective mass materials for intersubband devices, mixed As-Sb compounds, like GaAsxSb1-x or AlxIn1-xAsySb1-y, gain more and more attention. The growth of these materials, however, still provides significant challenges due to the complex interaction between As and Sb. In this work, we provide an in-depth study on the incorporation of Sb into the GaAsxSb1-x layers and compare our findings to the present literature on this topic. It is found that both the composition and the crystal quality of GaAsxSb1-x layers are strongly influenced by the growth rate due to the As-for-Sb exchange reaction which takes place at the growing surface, and that high crystal quality can be achieved when the growth is performed under Sb limited conditions.

  11. Enhancement of photocatalytic activity over Bi2O3/black-BiOCl heterojunction

    Science.gov (United States)

    Kim, Dahye; Jung, Dongwoon

    2017-04-01

    Several Bi2O3/BiOCl heterojunction compounds with different Bi2O3/BiOCl ratios were prepared by treating Bi2O3 with HCl. Within the Bi2O3/BiOCl heterojunction, white BiOCl was turned into black by thermal treatment. Upon the result, Bi2O3/black-BiOCl heterojunction could be prepared. The photocatalytic activities of samples were tested depending upon the Bi2O3/BiOCl ratio. Basically, Bi2O3/black-BiOCl samples showed advanced photocatalytic activity compared with the original Bi2O3/white-BiOCl. The highest photocatalytic efficiency was found in the Bi2O3/black-BiOCl when Bi2O3/BiOCl ratio was 15/85.

  12. Non-linear Electrical Characteristics of ZnO Modified by Trioxides Sb2O3, Bi2O3, Fe2O3, Al2O3 and La2O3

    Science.gov (United States)

    Mekap, Anita; Das, Piyush R.; Choudhary, R. N. P.

    2016-08-01

    The non-linear behavior of polycrystalline-ZnO-based voltage-dependent resistors is considered in the present study. A high-temperature solid-state reaction route was used to synthesize polycrystalline samples of ZnO modified by small amounts of the trioxides Sb2O3, Bi2O3, Fe2O3, etc. in various proportions. X-ray diffraction and scanning electron microscopy techniques were used to study the structural and microstructural characteristics of modified ZnO. Detailed studies of non-linear phenomena of the I-V characteristics, dielectric permittivity ( ɛ r), impedance ( Z), etc. of the samples have provided many interesting results. All the samples exhibited dielectric anomaly. Non-linear variation in polarization with electric field for all the samples was observed. Moreover, significant non-linearity in the I-V characteristics was observed in the breakdown region of all the samples at room temperature. The non-linear coefficient ( α) in different cases, i.e. for I- V, ɛ r- f, ɛ r- T, and ɛ r- Z, was calculated and found to be appreciable. The frequency dependence of ac conductivity suggests that the material obeys Jonscher's universal power law.

  13. Progress report on neutron beam experiments in Thailand: effects of antimony substitutions on the critical temperature of Bi-Pb-Sr-Ca-Cu-O compounds

    Energy Technology Data Exchange (ETDEWEB)

    Sangariyavanich, A.; Ampornrat, P. [Office of Atomic Energy for Peace, Bangkok (Thailand)

    1998-10-01

    Effects of systematic substitutions of antimony for bismuth in Bi{sub 1.8-x}Pb{sub 0.2}Sb{sub x}Sr{sub 2}Ca{sub 3}Cu{sub 4}O{sub 10} have been investigated. Fabrication of the specimens has been performed by solid state reaction in air. The samples were sintered between 820degC - 843degC for 65 hours and subsequently quenched in liquid nitrogen. The critical temperatures of most specimens as determined by standard four-probe technique was higher than 100 K. Phase identification by X-ray diffraction technique indicated that `2223` and `2234` were the predominant phases in these samples. (author)

  14. As, Bi, Hg, S, Sb, Sn and Te geochemistry of the J-M Reef, Stillwater Complex, Montana: constraints on the origin of PGE-enriched sulfides in layered intrusions

    Science.gov (United States)

    Zientek, M.L.; Fries, T.L.; Vian, R.W.

    1990-01-01

    The J-M Reef is an interval of disseminated sulfides in the Lower Banded series of the Stillwater Complex that is enriched in the platinum group elements (PGE). Palladium and Pt occur in solid solution in base-metal sulfides and as discrete PGE minerals. PGE minerals include sulfides, tellurides, arsenides, antimonides, bismuthides, and alloys with Fe, Sn, Hg, and Au. Several subpopulations can be delineated based on whole-rock chemical analyses for As, Bi, Cu, Hg, Pd, Pt, S, Sb and Te for samples collected from and adjacent to the J-M Reef. In general, samples from within the reef have higher Pt/Cu, Pd/Cu, Pd/Pt, Te/Bi and S/(Te+Bi) than those collected adjacent to the reef. Vertical compositional profiles through the reef suggest that Pd/Cu and Pt/Cu decrease systematically upsection from mineralized to barren rock. The majority of samples with elevated As, Sb and Hg occur adjacent to the reef, not within it, or in sulfide-poor rocks. Neither magma mixing nor fluid migration models readily explain why the minor quantities of sulfide minerals immediately adjacent to the sulfide-enriched layers that form the J-M Reef have different element ratios than the sulfide minerals that form the reef. If all the sulfides formed by exsolution during a magma mixing event and the modal proportion of sulfide now in the rocks are simply the result of mechanical processes that concentrated the sulfides into some layers and not others, then the composition of the sulfide would not be expected to be different. Models that rely upon ascending liquids or fluids are incompatible with the presence of sulfides that are not enriched in PGE immediately below or interlayered with the PGE-enriched sulfides layers. PGE-enriched postcumulus fluids should have reacted to the same extent with sulfides immediately outside the reef as within the reef. One explanation is that some of the sulfide minerals in the rocks outside the reef have a different origin than those that make up the reef. The

  15. A new solid solution compound with the Sr{sub 21}Mn{sub 4}Sb{sub 18} structure type. Sr{sub 13}Eu{sub 8}Cd{sub 3}Mn{sub 1}Sb{sub 18}

    Energy Technology Data Exchange (ETDEWEB)

    Kunz Wille, Elizabeth L.; Cooley, Joya A.; Fettinger, James C.; Kazem, Nasrin; Kauzlarich, Susan M. [California Univ., Davis, CA (United States). Dept. of Chemistry

    2017-09-01

    The title compound with the nominal formula, Sr{sub 13}Eu{sub 8}Cd{sub 3}Mn{sub 1}Sb{sub 18}, was synthesized by Sn-flux. Structure refinement was based on single-crystal X-ray diffractometer data. Employing the exact composition, the formula is Sr{sub 13.23}Eu{sub 7.77}Cd{sub 3.12}Mn{sub 0.88}Sb{sub 18} for the solid solution Sr{sub 21-x}Eu{sub x}Cd{sub 4-y}Mn{sub y}Sb{sub 18}. This phase adopts the Sr{sub 21}Mn{sub 4}Sb{sub 18} type structure with site preferences for both Eu and Cd. The structure crystallizes in the monoclinic system in space group C2/m and Z=4: a=18.1522(11), b=17.3096(10), c=17.7691(10) Aa, β=91.9638(8) , 6632 F{sup 2} values, 216 variables, R1=0.0254 and wR2=0.0563. Site selectivity of the elements in this new compound will be discussed in relationship with the Sr{sub 21}Mn{sub 4}Sb{sub 18} type structure and other related structure types. Temperature dependent magnetic susceptibility data reveal Curie-Weiss paramagnetism with an experimental moment of 19.3 μ{sub B}/f.u. and a Weiss constant of 0.4 K. Magnetic ordering is seen at low temperatures, with a transition temperature of 3.5 K.

  16. Bi-based superconductor

    Directory of Open Access Journals (Sweden)

    S E Mousavi

    2009-08-01

    Full Text Available   In this paper, Bi-Sr-Ca-Cu-O (BCSCCO system superconductor is made by the solid state reaction method. The effect of doping Pb, Cd, Sb, Cu and annealing time on the critical temperature and critical current density have been investigated. The microstructure and morphology of the samples have been studied by X-ray diffraction, scanning electron microscope and energy dispersive X-ray. The results show that the fraction of Bi-2223 phase in the Bi- based superconductor, critical temperature and critical current density depend on the annealing temperature, annealing time and the kind and amount of doping .

  17. Structural, elastic, electronic and optical properties of bi-alkali ...

    Indian Academy of Sciences (India)

    The structural parameters, elastic constants, electronic and optical properties of the bi-alkali antimonides (Na 2 KSb, Na 2 RbSb, Na 2 CsSb, K 2 RbSb, K 2 CsSb and Rb 2 CsSb) were calculated using state-of-the-art density functional theory. Different exchange-correlation potentials were adopted to predict the physical ...

  18. Flux pinning properties in BaPb0.77Bi0.23O3-δ compound

    Science.gov (United States)

    Yin, Peihuan; Xiao, Renfei; Xu, Xiaochun; Duan, Tianfeng; Wang, Zhihe

    2017-11-01

    The superconducting properties of BaPb0.77Bi0.23O3-δ compound were tested by transport and magnetization measurements from 2 to 14 K. The R-T curve at various magnetic fields is similar to that for MgB2 superconductors. The temperature dependence of resistance below 10% of normal state resistance follows Arrhenius law and the field dependence of effective flux pinning energy shows an exponential behavior, Ueff = U(0) exp(- 0.48 H) . The Hc-T line down to 2 K displays a power law, Hc(T) ∝(1 - T / Tc)n . The field dependence of flux pinning force displays two peaks originated from the intragrains and intergrains, respectively. The scaling result of Dew-Hughes model, Fp = Ahp(1 - h)q , suggests that the flux pinning in the sample is the collective pinning of normal surface and point centers. The field dependence of critical current density shows a power law in the low magnetic field region and an exponential behavior, Jc = Jc0 exp(- βH) , in high magnetic field region.

  19. Enzyme-mediated coupling of a bi-functional phenolic compound onto wool to enhance its physical, mechanical and functional properties

    OpenAIRE

    Gaffar Hossain, Kh. M.; Díaz González, María; Riva Juan, Ascensión; Tzanov, Tzanko

    2009-01-01

    Electronic version of an article published as "Enzyme and microbial technology", 08 Desembre 2009, p. 1-5 Wool fibres have been modified with nordihydroguaiaretic acid (NDGA) to improve their performance at use. This water insoluble bi-functional phenolic compound has been grafted on wool through a laccase enzyme catalyzed reaction in an aqueous-ethanol mixture. The capacity of laccase to oxidise NDGA in this aqueous-organic medium has been studied electrochemicaly. The increase of CH2, CH...

  20. IMI - oral biopharmaceutics tools project - evaluation of bottom-up PBPK prediction success part 1: Characterisation of the OrBiTo database of compounds.

    Science.gov (United States)

    Margolskee, Alison; Darwich, Adam S; Pepin, Xavier; Pathak, Shriram M; Bolger, Michael B; Aarons, Leon; Rostami-Hodjegan, Amin; Angstenberger, Jonas; Graf, Franziska; Laplanche, Loic; Müller, Thomas; Carlert, Sara; Daga, Pankaj; Murphy, Dónal; Tannergren, Christer; Yasin, Mohammed; Greschat-Schade, Susanne; Mück, Wolfgang; Muenster, Uwe; van der Mey, Dorina; Frank, Kerstin Julia; Lloyd, Richard; Adriaenssen, Lieve; Bevernage, Jan; De Zwart, Loeckie; Swerts, Dominique; Tistaert, Christophe; Van Den Bergh, An; Van Peer, Achiel; Beato, Stefania; Nguyen-Trung, Anh-Thu; Bennett, Joanne; McAllister, Mark; Wong, Mei; Zane, Patricia; Ollier, Céline; Vicat, Pascale; Kolhmann, Markus; Marker, Alexander; Brun, Priscilla; Mazuir, Florent; Beilles, Stéphane; Venczel, Marta; Boulenc, Xavier; Loos, Petra; Lennernäs, Hans; Abrahamsson, Bertil

    2017-01-01

    Predicting oral bioavailability (Foral) is of importance for estimating systemic exposure of orally administered drugs. Physiologically-based pharmacokinetic (PBPK) modelling and simulation have been applied extensively in biopharmaceutics recently. The Oral Biopharmaceutical Tools (OrBiTo) project (Innovative Medicines Initiative) aims to develop and improve upon biopharmaceutical tools, including PBPK absorption models. A large-scale evaluation of PBPK models may be considered the first step. Here we characterise the OrBiTo active pharmaceutical ingredient (API) database for use in a large-scale simulation study. The OrBiTo database comprised 83 APIs and 1475 study arms. The database displayed a median logP of 3.60 (2.40-4.58), human blood-to-plasma ratio of 0.62 (0.57-0.71), and fraction unbound in plasma of 0.05 (0.01-0.17). The database mainly consisted of basic compounds (48.19%) and Biopharmaceutics Classification System class II compounds (55.81%). Median human intravenous clearance was 16.9L/h (interquartile range: 11.6-43.6L/h; n=23), volume of distribution was 80.8L (54.5-239L; n=23). The majority of oral formulations were immediate release (IR: 87.6%). Human Foral displayed a median of 0.415 (0.203-0.724; n=22) for IR formulations. The OrBiTo database was found to be largely representative of previously published datasets. 43 of the APIs were found to satisfy the minimum inclusion criteria for the simulation exercise, and many of these have significant gaps of other key parameters, which could potentially impact the interpretability of the simulation outcome. However, the OrBiTo simulation exercise represents a unique opportunity to perform a large-scale evaluation of the PBPK approach to predicting oral biopharmaceutics. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Electrocatalytic mechanism and kinetics of SOMs oxidation on ordered PtPb and PtBi intermetallic compounds: DEMS and FTIRS study.

    Science.gov (United States)

    Wang, Hongsen; Alden, Laif; Disalvo, F J; Abruña, Héctor D

    2008-07-07

    The electrocatalytic activities and mechanisms of PtPb and PtBi ordered intermetallic phases towards formic acid, formaldehyde and methanol oxidation have been studied by DEMS and FTIRS, and the results compared to those for a pure polycrystalline platinum electrode. While PtPb exhibits an enhanced electrocatalytic activity for the oxidation of all three organic molecules when compared to a Pt electrode, PtBi exhibits an enhanced catalytic activity towards formic acid and formaldehyde oxidation, but not methanol. FTIRS data indicate that adsorbed CO does not form on PtPb or PtBi intermetallic compounds during the oxidation of formic acid, formaldehyde and methanol, and therefore their oxidation on both PtPb and PtBi intermetallic compounds proceeds via a non-CO(ads) pathway. Quantitative DEMS measurements indicate that only CO(2) was detected as a final product during formic acid oxidation on Pt, PtPb and PtBi electrodes. At a smooth polycrystalline platinum electrode, the oxidation of formaldehyde and methanol produces mainly intermediates (formaldehyde and formic acid), while CO(2) is a minor product. In contrast, CO(2) is the major product for formaldehyde and methanol oxidation at a PtPb electrode. The high current efficiency of CO(2) formation for methanol and formaldehyde oxidation at a PtPb electrode can be ascribed to the complete dehydrogenation of formaldehyde and formic acid due to electronic effects. The low onset potential, high current density and high CO(2) yield make PtPb one of the most promising electrocatalysts for fuel cell applications using small organic molecules as fuels.

  2. Low-temperature synthesis and investigations on photocatalytic activity of nanoparticles BiFeO3 for methylene blue and methylene orange degradation and some toxic organic compounds

    Science.gov (United States)

    Nhiem Dao, Ngoc; Luu, Minh Dai; Chuc Pham, Ngoc; Dung Doan, Trung; Nguyen, Thi Ha Chi; Bac Nguyen, Quang; Lim Duong, Thi

    2016-12-01

    The photocatalytic BiFeO3 perovskite nanoparticles were fabricated by gel combustion method using polyvinyl alcohol and corresponding metal nitrate precursors under the optimum mild conditions such as pH 2, gel formation temperature of 80 °C, metal/polyvinyl alcohol molar ratio of 1/3, metal molar ratio Bi/Fe of 1/1 and calcination temperature at 500 °C for 2 h. The prepared sample was characterized by x-ray diffraction, field scanning electron microscopy, transmission electron microscopy, Brunauer-Emmetl-Teller nitrogen adsorption method at 77 K, energy dispersive x-ray spectroscopy, ultraviolet-visible light spectrophotometry, and thermal analysis. The effects of molar ratios of starting material and calcination temperature on phase formation and morphology were investigated. The degradation of methylene blue, methylene orange and some toxic organic compounds such as phenol and diazinon under visible light irradiation by photocatalytic BiFeO3 nanoparticles were evaluated at different parameters and conditions such as the light intensity determined from the light source to the measured sample, the addition H2O2, reaction time and the regeneration performance. Obtained results showed that the synthesized perovskite BiFeO3 nanoparticles for the optimized sample have a size smaller than 50 nm and the high mean surface area of 50 m2 g-1. Degradation efficiency was almost 90.0% for methylene blue and 80.0% for methylene orange with added H2O2 after 30 min of reaction. After the 3rd time of regeneration, the BiFeO3 nanoparticles still have 92.8% of the degradation performance for removing methylene blue. Phenol and diazinon toxic compound were degraded with the performance of 92.42% and 85.7%, respectively, for 150 min

  3. Imaging Dirac-mass disorder from magnetic dopant atoms in the ferromagnetic topological insulator Crx(Bi0.1Sb0.9)2-xTe3.

    Science.gov (United States)

    Lee, Inhee; Kim, Chung Koo; Lee, Jinho; Billinge, Simon J L; Zhong, Ruidan; Schneeloch, John A; Liu, Tiansheng; Valla, Tonica; Tranquada, John M; Gu, Genda; Davis, J C Séamus

    2015-02-03

    To achieve and use the most exotic electronic phenomena predicted for the surface states of 3D topological insulators (TIs), it is necessary to open a "Dirac-mass gap" in their spectrum by breaking time-reversal symmetry. Use of magnetic dopant atoms to generate a ferromagnetic state is the most widely applied approach. However, it is unknown how the spatial arrangements of the magnetic dopant atoms influence the Dirac-mass gap at the atomic scale or, conversely, whether the ferromagnetic interactions between dopant atoms are influenced by the topological surface states. Here we image the locations of the magnetic (Cr) dopant atoms in the ferromagnetic TI Cr0.08(Bi0.1Sb0.9)1.92Te3. Simultaneous visualization of the Dirac-mass gap Δ(r) reveals its intense disorder, which we demonstrate is directly related to fluctuations in n(r), the Cr atom areal density in the termination layer. We find the relationship of surface-state Fermi wavevectors to the anisotropic structure of Δ(r) not inconsistent with predictions for surface ferromagnetism mediated by those states. Moreover, despite the intense Dirac-mass disorder, the anticipated relationship [Formula: see text] is confirmed throughout and exhibits an electron-dopant interaction energy J* = 145 meV·nm(2). These observations reveal how magnetic dopant atoms actually generate the TI mass gap locally and that, to achieve the novel physics expected of time-reversal symmetry breaking TI materials, control of the resulting Dirac-mass gap disorder will be essential.

  4. FP-APW+lo study of the elastic, electronic and optical properties for the cubic antiperovskite ANSr{sub 3} (A=As, Sb and Bi) under pressure effect

    Energy Technology Data Exchange (ETDEWEB)

    Hichour, M. [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, 29000 Mascara (Algeria); Khenata, R., E-mail: Khenta_rabah@yahoo.f [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, 29000 Mascara (Algeria); Department of Physics, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Rached, D. [Physics Department, Faculty of Science, University of Sidi-Bel-Abbes, 22000 (Algeria); Hachemaoui, M. [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, 29000 Mascara (Algeria); Bouhemadou, A., E-mail: a_bouhemadou@yahoo.f [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria); Department of Physics, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Reshak, Ali. H. [Institute of Physical Biology, University of S. Bohemia, Nove Hrady 373 33 (Czech Republic); Semari, F. [Physics Department, Faculty of Science, University of Sidi-Bel-Abbes, 22000 (Algeria)

    2010-04-01

    Structural, electronic, elastic and optical properties of the cubic-antiperovskite-type ANSr{sub 3,} with A=As, Sb and Bi, are studied under pressure effect using the full-relativistic version of the full-potential augmented plane wave plus local orbitals method (FP-APW+lo). The exchange-correlation potential is treated by the generalized gradient approximation within the scheme of Perdew, Burke and Ernzerhof (GGA-PBE). Also we have used Engel and Vosko GGA formalism (GGA-EV) to improve the band gap results. The calculated bulk properties, including lattice constants, bulk moduli and their pressure derivatives are in reasonable agreement with the available data. The elastic constants C{sub ij} and their pressure dependences are calculated using the total energy-strain technique. The shear modulus, Young's modulus, Poisson's ratio and Lame's coefficients are estimated in the framework of the Voigt-Reuss-Hill approximation for ideal polycrystalline ANSr{sub 3} aggregates. The Debye temperature is estimated from the average sound velocity. Energy band structures show that the investigated materials are direct energy band gap semiconductors. Analysis of the density of states and charge density distribution shows that the bonding is a mixture of covalent and ionic character. For the first time, the real and imaginary parts of the dielectric function epsilon(omega), the refractive index n(omega), the reflectivity R(omega) and the energy loss function L(omega) are calculated for radiation up to 18 eV.

  5. Regional atmospheric deposition patterns of Ag, As, Bi, Cd, Hg, Mo, Sb and Tl in a 188,000 km 2 area in the European arctic as displayed by terrestrial moss samples-long-range atmospheric transport vs local impact

    Science.gov (United States)

    Reimann, Clemens; De Caritat, Patrice; Halleraker, Jo H.; Finne, Tor Erik; Boyd, Rognvald; Jæger, Øystein; Volden, Tore; Kashulina, Galina; Bogatyrev, Igor; Chekushin, Viktor; Pavlov, Vladimir; Äyräs, Matti; Räisänen, Marja Liisa; Niskavaara, Heikki

    The regional atmospheric deposition patterns of Ag, As, Bi, Cd, Hg, Mo, Sb and Tl have been mapped in a 188,000 km2 area of the European Arctic (N Finland, N Norway, NW Russia) using the moss technique. The Russian nickel mining and smelting industry (Nikel and Zapoljarnij (Pechenganikel) and Monchegorsk (Severonikel)) in the eastern part of the survey area represents two of the largest point sources for S0 2 and metal emissions on a world wide basis. In contrast, parts of northern Finland and northern Norway represent still some of the most pristine areas in Europe. The terrestrial mosses Hylocomium splendens and Pleurozium schreberi were used as monitors of airborne deposition. Samples in all three countries were collected during the summer of 1995 and analysed in one laboratory using ICP-MS. Maps for most elements clearly show elevated element concentrations near the industrial sites and delineate the extent of contamination. Pollution follows the main wind and topographical directions in the area (N-S). The gradients of deposition are rather steep. Background levels for all the elements are reached within 150-200 km from the industrial plants. The relative importance of long-range atmospheric transport of air pollutants from industrial point sources on the world wide increase of heavy metals observed in the atmosphere is thus debatable for many elements. Increasing population and traffic density, accompanied by increasing local dust levels, may play a much more important role than industrial emissions. The regional distribution patterns as displayed in the maps show some striking differences between the elements. The regional distribution of Hg and TI in the survey area is completely dominated by sources other than industry.

  6. Properties and Microstructures of Sn-Bi-X Lead-Free Solders

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2016-01-01

    Full Text Available The Sn-Bi base lead-free solders are proposed as one of the most popular alloys due to the low melting temperature (eutectic point: 139°C and low cost. However, they are not widely used because of the lower wettability, fatigue resistance, and elongation compared to traditional Sn-Pb solders. So the alloying is considered as an effective way to improve the properties of Sn-Bi solders with the addition of elements (Al, Cu, Zn, Ga, Ag, In, Sb, and rare earth and nanoparticles. In this paper, the development of Sn-Bi lead-free solders bearing elements and nanoparticles was reviewed. The variation of wettability, melting characteristic, electromigration, mechanical properties, microstructures, intermetallic compounds reaction, and creep behaviors was analyzed systematically, which can provide a reference for investigation of Sn-Bi base solders.

  7. Evidence for Point Nodes in the Superconducting Gap Function in the Filled Skutterudite Heavy-Fermion Compound PrOs4Sb12: 123Sb-NQR Study under Pressure

    Science.gov (United States)

    Katayama, Kouta; Kawasaki, Shinji; Nishiyama, Masahide; Sugawara, Hitoshi; Kikuchi, Daisuke; Sato, Hideyuki; Zheng, Guo-qing

    2007-02-01

    We report 123Sb nuclear quadrupole resonance (NQR) measurements of the filled skutterudite heavy-fermion superconductor PrOs4Sb12 under high pressures of 1.91 and 2.34 GPa. The temperature dependence of NQR frequency and the spin-lattice relaxation rate 1/T1 indicate that the crystal-electric-field splitting ΔCEF between the ground state Γ1 singlet and the first excited state Γ4(2) triplet decreases with increasing pressure. The 1/T1 below Tc = 1.55 K at P = 1.91 GPa shows a power-law temperature variation and is proportional to T5 at temperatures considerably below Tc, which indicates the existence of point nodes in the superconducting gap function. The data can be well fitted by the gap model Δ(θ) = Δ0\\sinθ with Δ0 = 3.08kBTc. The relation between the superconductivity and the quadrupole fluctuations associated with the Γ4(2) state is discussed.

  8. Bismuth chalcogenide compounds Bi 2 × 3 (X=O, S, Se): Applications in electrochemical energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Jiangfeng; Bi, Xuanxuan; Jiang, Yu; Li, Liang; Lu, Jun

    2017-04-01

    Bismuth chalcogenides Bi2×3 (X=O, S, Se) represent a unique type of materials in diverse polymorphs and configurations. Multiple intrinsic features of Bi2×3 such as narrow bandgap, ion conductivity, and environmental friendliness, have render them attractive materials for a wide array of energy applications. In particular, their rich structural voids and the alloying capability of Bi enable the chalcogenides to be alternative electrodes for energy storage such as hydrogen (H), lithium (Li), sodium (Na) storage and supercapacitors. However, the low conductivity and poor electrochemical cycling are two key challenges for the practical utilization of Bi2×3 electrodes. Great efforts have been devoted to mitigate these challenges and remarkable progresses have been achieved, mainly taking profit of nanotechnology and material compositing engineering. In this short review, we summarize state-of-the-art research advances in the rational design of diverse Bi2×3 electrodes and their electrochemical energy storage performance for H, Li, and Na and supercapacitors. We also highlight the key technical issues at present and provide insights for the future development of bismuth based materials in electrochemical energy storage devices.

  9. Partitioning of platinum-group elements (PGE) and chalcogens (Se, Te, As, Sb, Bi) between monosulfide-solid solution (MSS), intermediate solid solution (ISS) and sulfide liquid at controlled fO2-fS2 conditions

    Science.gov (United States)

    Liu, Yanan; Brenan, James

    2015-06-01

    In order to better understand the behavior of highly siderophile elements (HSEs: Os, Ir, Ru, Rh, Pt, Pd, Au, Re), Ag, Pb and chalcogens (As, Se, Sb, Te and Bi) during the solidification of sulfide magmas, we have conducted a series of experiments to measure partition coefficients (D values) between monosulfide solid solution (MSS) and sulfide melt, as well as MSS and intermediate solid solution (ISS), at 0.1 MPa and 860-926 °C, log fS2 -3.0 to -2.2 (similar to the Pt-PtS buffer), with fO2 controlled at the fayalite-magnetite-quartz (FMQ) buffer. The IPGEs (Os, Ir, Ru), Rh and Re are found to be compatible in MSS relative to sulfide melt with D values ranging from ∼20 to ∼5, and DRe/DOs of ∼0.5. Pd, Pt, Au, Ag, Pb, as well as the chalcogens, are incompatible in MSS, with D values ranging from ∼0.1 to ∼1 × 10-3. For the same metal/sulfur ratio, D values for the IPGEs, Rh and Re are systematically larger than most past studies, correlating with higher oxygen content in the sulfide liquid, reflecting the significant effect of oxygen on increasing the activity coefficients for these elements in the melt phase. MSS/ISS partitioning experiments reveal that Ru, Os, Ir, Rh and Re are partitioned into MSS by a factor of >50, whereas Pd, Pt, Ag, Au and the chalcogens partition from weakly (Se, As) to strongly (Ag, Au) into ISS. Uniformly low MSS- and ISS- melt partition coefficients for the chalcogens, Pt, Pd, Ag and Au will lead to enrichment in the residual sulfide liquid, but D values are generally too large to reach early saturation in Pt-Pd-chalcogen-rich accessory minerals, based on current solubility estimates. Instead, these phases likely precipitate at the last dregs of crystallization. Modeled evolution curves for the PGEs and chalcogens are in reasonably good agreement with whole-rock sulfide compositions for the McCreedy East deposit (Sudbury, Ontario), consistent with an origin by crystallization of MSS, then MSS + ISS from sulfide magma.

  10. Fractionation of Li, Be, Ga, Nb, Ta, In, Sn, Sb, W and Bi in the peraluminous Early Permian Variscan granites of the Cornubian Batholith: Precursor processes to magmatic-hydrothermal mineralisation

    Science.gov (United States)

    Simons, Beth; Andersen, Jens C. Ø.; Shail, Robin K.; Jenner, Frances E.

    2017-05-01

    The Early Permian Variscan Cornubian Batholith is a peraluminous, composite pluton intruded into Devonian and Carboniferous metamorphosed sedimentary and volcanic rocks. Within the batholith there are: G1 (two-mica), G2 (muscovite), G3 (biotite), G4 (tourmaline) and G5 (topaz) granites. G1-G2 and G3-G4 are derived from greywacke sources and linked through fractionation of assemblages dominated by feldspars and biotite, with minor mantle involvement in G3. G5 formed though flux-induced biotite-dominate melting in the lower crust during granulite facies metamorphism. Fractionation enriched G2 granites in Li (average 315 ppm), Be (12 ppm), Ta (4.4 ppm), In (74 ppb), Sn (18 ppm) and W (12 ppm) relative to crustal abundances and G1 granites. Gallium (24 ppm), Nb (16 ppm) and Bi (0.46 ppm) are not significantly enriched during fractionation, implying they are more compatible in the fractionating assemblage. Sb (0.16 ppm) is depleted in G1-G2 relative to the average upper and lower continental crust. Muscovite, a late-stage magmatic/subsolidus mineral, is the major host of Li, Nb, In, Sn and W in G2 granites. G2 granites are spatially associated with W-Sn greisen mineralisation. Fractionation within the younger G3-G4 granite system enriched Li (average 364 ppm), Ga (28 ppm), In (80 ppb), Sn (14 ppm), Nb (27 ppm), Ta (4.6 ppm), W (6.3 ppm) and Bi (0.61 ppm) in the G4 granites with retention of Be in G3 granites due to partitioning of Be into cordierite during fractionation. The distribution of Nb and Ta is controlled by accessory phases such as rutile within the G4 granites, facilitated by high F and lowering the melt temperature, leading to disseminated Nb and Ta mineralisation. Lithium, In, Sn and W are hosted in biotite micas which may prove favourable for breakdown on ingress of hydrothermal fluids. Higher degrees of scattering on trace element plots may be attributable to fluid-rock interactions or variability within the magma chamber. The G3-G4 system is more boron

  11. Tuning ferroic states in La doped BiFeO{sub 3}-PbTiO{sub 3} displacive multiferroic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Cótica, L. F., E-mail: lfcotica@dfi.uem.br [Department of Electrical and Computer Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249 (United States); Department of Physics, State University of Maringá, Maringá, PR 87020-900 (Brazil); Freitas, V. F.; Protzek, O. A. [Department of Physics, State University of Maringá, Maringá, PR 87020-900 (Brazil); Eiras, J. A.; Garcia, D. [Department of Physics, Federal University of São Carlos, São Carlos, SP 13565-905 (Brazil); Yokaichiya, F.; Santos, I. A. [Nuclear and Energy Research Institute, São Paulo, SP 05508-000 (Brazil); Guo, R.; Bhalla, A. S. [Department of Electrical and Computer Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249 (United States)

    2014-07-21

    In this manuscript, X-ray and high-resolution neutron powder diffraction investigations, associated with Rietveld refinements, magnetic hysteresis curves and a modeling of electron-density distributions around the ions, are used to describe the driving forces responsible for tuning the ferroic states in La doped (0.6)BiFeO{sub 3}-(0.4)PbTiO{sub 3} compositions. The intrinsic relations between the ferroic orders and the structural arrangements (angles, distances and electron-density distributions around the ions) are revealed, helping in the understanding of some aspects comprising the ferroic properties of perovskite-based displacive multiferroic compounds.

  12. Hydrothermal synthesis and crystal structure of a new lithium copper bismuth oxide, LiCuBiO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kumada, Nobuhiro, E-mail: kumada@yamanashi.ac.jp [Center for Crystal Science and Technology, University of Yamanashi, Miyamae-cho 7-32, Kofu 400-8511 (Japan); Nakamura, Ayumi [Center for Crystal Science and Technology, University of Yamanashi, Miyamae-cho 7-32, Kofu 400-8511 (Japan); Miura, Akira [Center for Crystal Science and Technology, University of Yamanashi, Miyamae-cho 7-32, Kofu 400-8511 (Japan); Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo 060-8628 (Japan); Takei, Takahiro [Center for Crystal Science and Technology, University of Yamanashi, Miyamae-cho 7-32, Kofu 400-8511 (Japan); Azuma, Masaki; Yamamoto, Hajime [Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku Yokohama, Kanagawa 226-8503 (Japan); Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro [Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526 (Japan)

    2017-01-15

    A new lithium copper bismuth oxide, LiCuBiO{sub 4} was prepared by hydrothermal reaction using NaBiO{sub 3}0.1*4H{sub 2}O. The crystal structural model of this compound was refined by using synchrotron X-ray powder diffraction data. This bismuthate has the LiCuSbO{sub 4} related structure with the orthorhombic cell (Space group: Pnma) of a=10.9096(9), b=5.8113(5) and c=5.0073(4) Å, and the final R-factors were R{sub wp}=4.84 and R{sub p}=3.58%. This compound is the first example of a lithium copper bismuthate containing Bi{sup 5+}. An antiferromagnetic ordering of Cu{sup 2+} moment was observed at 6 K. - Graphical abstract: In the crystal structure of LiCuBiO{sub 4} all metal atoms are coordinated octahedrally by six O atoms and LiO{sub 6} and CuO{sub 6} octahedra form the one-dimensional chains by edge-sharing along the b-axis. The LiO{sub 6} and CuO{sub 6} chains form the layer by face-sharing in the bc plane. The Bi atoms are placed in that interlayer and BiO{sub 6} octahedra are edge-sharing with LiO{sub 6} and CuO{sub 6} octahedra. - Highlights: • A new lithium copper bismuth oxide, LiCuBiO{sub 4} is prepared by hydrothermal reaction. • The crystal structure of LiCuBiO{sub 4} is closely related with that of LiCuSbO{sub 4}. • This new compound exhibits an antiferromagnetic ordering of Cu{sup 2+} moment at 6 K.

  13. Structural transformations in intermetallic electrodes for lithium batteries : an in situ XRD study of lithiated MnSb and Mn{sub 2}Sb.

    Energy Technology Data Exchange (ETDEWEB)

    Fransson, L. M. L.; Vaughey, J. T.; Edstrom, K.; Thackeray, M. M.; Chemical Engineering; Uppsala Univ.

    2003-01-01

    The electrochemical reactions of lithium with MnSb (NiAs-type structure) and Mn{sub 2}Sb (Cu{sub 2}Sb-type structure) have been investigated by in situ X-ray diffraction. Lithiation of MnSb proceeds via an intermediate LiMnSb structure before transforming, with Mn extrusion, to Li{sub 3}Sb. The reaction is reversible. On delithiation, the X-ray data show solid-solution behavior between Li{sub 3}Sb and LiMnSb, which is facilitated by the strong structural relationship between these two compounds. MnSb electrodes deliver a rechargeable capacity of 330 mAh/g when cycled between 1.5 and 0 V vs. metallic lithium. By contrast, the initial reaction of Mn{sub 2}Sb with lithium proceeds almost directly to Li{sub 3}Sb with little LiMnSb formation. Thereafter, Mn{sub 2}Sb electrodes behave in an almost identical manner to MnSb electrodes, but deliver a rechargeable capacity of less than 300 mAh/g because of the surplus Mn in the electrode. The electrochemical and structural properties of MnSb and Mn{sub 2}Sb are compared with the structurally related compounds Cu{sub 6}Sn{sub 5} (NiAs-type structure) and Cu{sub 2}Sb, respectively.

  14. Molecular beam epitaxy growth of InSb1−xBix thin films

    DEFF Research Database (Denmark)

    Song, Yuxin; Wang, Shumin; Saha Roy, Ivy

    2013-01-01

    Molecular beam epitaxy growth for InSb1−xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology...

  15. Peculiarities of thermoelectric half-Heusler phase formation in Gd-Ni-Sb and Lu-Ni-Sb ternary systems

    Energy Technology Data Exchange (ETDEWEB)

    Romaka, V.V., E-mail: romakav@lp.edu.ua [Department of Applied Material Science and Materials Engineering, Lviv Polytechnic National University, Ustyyanovycha Str. 5, 79013 Lviv (Ukraine); Romaka, L.; Horyn, A. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv (Ukraine); Rogl, P. [Institute of Materials Chemistry and Research, University of Vienna, Währingerstrasse 42, A-1090 Wien (Austria); Stadnyk, Yu; Melnychenko, N. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mefodiya str. 6, 79005 Lviv (Ukraine); Orlovskyy, M.; Krayovskyy, V. [Department of Applied Material Science and Materials Engineering, Lviv Polytechnic National University, Ustyyanovycha Str. 5, 79013 Lviv (Ukraine)

    2016-07-15

    The phase equilibria in the Gd–Ni–Sb and Lu-Ni-Sb ternary systems were studied at 873 K by X-ray and metallographic analyses in the whole concentration range. The interaction of the elements in the Gd–Ni–Sb system results the formation of five ternary compounds at investigated temperature: Gd{sub 5}Ni{sub 2}Sb (Mo{sub 5}SiB{sub 2}-type), Gd{sub 5}NiSb{sub 2} (Yb{sub 5}Sb{sub 3}-type), GdNiSb (MgAgAs-type), Gd{sub 3}Ni{sub 6}Sb{sub 5} (Y{sub 3}Ni{sub 6}Sb{sub 5}-type), and GdNi{sub 0.72}Sb{sub 2} (HfCuSi{sub 2}-type). At investigated temperature the Lu-Ni-Sb system is characterized by formation of the LuNiSb (MgAgAs-type), Lu{sub 5}Ni{sub 2}Sb (Mo{sub 5}SiB{sub 2}-type), and Lu{sub 5}Ni{sub 0.56}Sb{sub 2.44} (Yb{sub 5}Sb{sub 3}-type) compounds. The disordering in the crystal structure of half-Heusler GdNiSb and LuNiSb was revealed by EPMA and studied by means of Rietveld refinement and DFT modeling. The performed electronic structure calculations are in good agreement with electrical transport property studies. - Graphical abstract: Crystal structure model and electron localization function of Lu{sub 5}Ni{sub 2}Sb. Display Omitted - Highlights: • Gd-Ni-Sb and Lu-Ni-Sb phase diagrams were constructed at 873 K. • GdNiSb and LuNiSb are characterized by disordered crystal structure. • Crystal structure optimization with DFT calculations confirmed crystal structure disorder in GdNiSb and LuNiSb.

  16. Lower lattice thermal conductivity in SbAs than As or Sb monolayers: a first-principles study.

    Science.gov (United States)

    Guo, San-Dong; Liu, Jiang-Tao

    2017-12-06

    Phonon transport in group-VA element (As, Sb and Bi) monolayer semiconductors has been widely investigated in theory, and, of them, monolayer Sb (antimonene) has recently been synthesized. In this work, phonon transport in monolayer SbAs is investigated with a combination of first-principles calculations and the linearized phonon Boltzmann equation. It is found that the lattice thermal conductivity of monolayer SbAs is lower than those of both monolayer As and Sb, and the corresponding sheet thermal conductance is 28.8 W K-1 at room temperature. To understand the lower lattice thermal conductivity in monolayer SbAs than those in monolayer As and Sb, the group velocities and phonon lifetimes of monolayer As, SbAs and Sb are calculated. The calculated results show that the group velocities of monolayer SbAs are between those of monolayer As and Sb, but that the phonon lifetimes of SbAs are smaller than those of both monolayer As and Sb. Hence, the low lattice thermal conductivity in monolayer SbAs is attributed to very small phonon lifetimes. Unexpectedly, the ZA branch has very little contribution to the total thermal conductivity, only 2.4%, which is obviously different from those of monolayer As and Sb with very large contributions. This can be explained by very small phonon lifetimes for the ZA branch of monolayer SbAs. The lower lattice thermal conductivity of monolayer SbAs compared to that of monolayer As or Sb can be understood by the alloying of As (Sb) with Sb (As), which should introduce phonon point defect scattering. We also consider the isotope and size effects on the lattice thermal conductivity. It is found that isotope scattering produces a neglectful effect, and the lattice thermal conductivity with a characteristic length smaller than 30 nm can reach a decrease of about 47%. These results may offer perspectives on tuning the lattice thermal conductivity by the mixture of multiple elements for applications of thermal management and thermoelectricity

  17. Electronic and optical properties of the LiCdX (X = N, P, As and Sb) filled-tetrahedral compounds with the Tran–Blaha modified Becke–Johnson density functional

    Energy Technology Data Exchange (ETDEWEB)

    Bouhemadou, A., E-mail: a_bouhemadou@yahoo.fr [Laboratory for Developing New Materials and their Characterization, University of Setif 1, Setif 19000 (Algeria); Bin-Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Department of Physics, Faculty of Science & Humanitarian Studies, Salman Bin Abdalaziz University, Alkharj 11942 (Saudi Arabia); Allali, D. [Laboratory for Developing New Materials and their Characterization, University of Setif 1, Setif 19000 (Algeria); Al-Otaibi, S.M. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria); Al-Douri, Y. [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, Kangar, Perlis 01000 (Malaysia); Chegaar, M. [Department of Physics, Faculty of Science, University of Setif 1, Setif 19000 (Algeria); Reshak, A.H. [New Technologies-Research Center, University of West Bohemia, Univerzitni 8, Pilson 306 14 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, Kangar, Perlis 01007 (Malaysia)

    2015-04-15

    Highlights: • Electronic and optical properties of the LiCdX compounds have been predicted. • Tran–Blaha-modified Becke–Johnson functional significantly improves the band gap. • We predict a direct band gap in all of the considered LiCdX compounds. • Origin of the peaks in the optical spectra is determined. - Abstract: The structural, electronic and optical properties of the LiCdN, LiCdP, LiCdAs and LiCdSb filled-tetrahedral compounds have been explored from first-principles. The calculated structural parameters are consistent with the available experimental results. Since DFT with the common LDA and GGA underestimates the band gap, we use a new developed functional able to accurately describe the electronic structure of semiconductors, namely the Tran–Blaha-modified Becke–Johnson potential. The four investigated compounds demonstrate semiconducting behavior with direct band gap ranging from about 0.32 to 1.65 eV. The charge-carrier effective masses are evaluated at the topmost valence band and at the bottommost conduction band. The evolution of the value and nature of the energy band gap under pressure effect is also investigated. The frequency-dependent complex dielectric function and some macroscopic optical constants are estimated. The microscopic origins of the structures in the optical spectra are determined in terms of the calculated energy band structures.

  18. The new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} and the role of dimensionality in the Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub n} series

    Energy Technology Data Exchange (ETDEWEB)

    Trump, Benjamin A., E-mail: btrump1@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218 (United States); Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218 (United States); Livi, Kenneth J.T. [HRAEM Facility, Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218 (United States); McQueen, Tyrel M., E-mail: mcqueen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218 (United States); Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2014-01-15

    The synthesis and physical properties of the new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} are reported. Transmission electron microscopy and powder X-ray diffraction show that the structure consists of alternating rock-salt type BiSe layers and hexagonal (TiSe{sub 2}){sub 2} double layers. Resistivity, specific heat, and magnetization measurements show that it has metallic and diamagnetic behaviors. These results are interpreted and discussed in the context of the transition between single-layer (BiSe){sub 1.13}(TiSe{sub 2}), which shows no charge density wave, and infinite-layered (bulk) 1T-TiSe{sub 2}, which undergoes a charge density wave transition at T=202 K. Intercalation with copper, Cu{sub x}(BiSe){sub 1.15}(TiSe{sub 2}){sub 2}, (0≤x≤0.10) is also reported, but unlike Cu{sub x}TiSe{sub 2}, no superconductivity is observed down to T=0.05 K. Thus, the series Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub n} provides an effective approach to elucidate the impact of dimensionality on charge density wave formation and superconductivity. - Graphical abstract: The newly discovered misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2} shown in the series (BiSe){sub 1+δ}(TiSe{sub 2}){sub n}. Display Omitted - Highlights: • Reports the structure and properties of the new misfit compound (BiSe){sub 1.15}(TiSe{sub 2}){sub 2}. • The structure consists of a rock salt type BiSe layer and a double (TiSe{sub 2}){sub 2} layer. • The n=1, 2 misfits (BiSe){sub 1+δ}(TiSe{sub 2}){sub n} are found not to exhibit CDW transitions. • Evidence is presented that there is likely a low-lying CDW excited state. • The series Cu{sub x}(BiSe){sub 1+δ}(TiSe{sub 2}){sub 2} does not superconduct, unlike Cu{sub x}TiSe{sub 2}.

  19. Compound

    Indian Academy of Sciences (India)

    UV-vis spectra showing solvent effects on compounds (6). Figure S4. UV-vis spectra showing solvent effects on compounds (9). Figure S5. UV-vis spectra showing solvent ___, acidic--- and basic -□- effects on compound (8) in CH2Cl2 solution. Table S1. 1H and 13C NMR spectral data of salicylaldimine Schiff bases (5-8).

  20. Electronic structure of R Sb (R =Y , Ce, Gd, Dy, Ho, Tm, Lu) studied by angle-resolved photoemission spectroscopy

    Science.gov (United States)

    Wu, Yun; Lee, Yongbin; Kong, Tai; Mou, Daixiang; Jiang, Rui; Huang, Lunan; Bud'ko, S. L.; Canfield, P. C.; Kaminski, Adam

    2017-07-01

    We use high-resolution angle-resolved photoemission spectroscopy (ARPES) and electronic structure calculations to study the electronic properties of rare-earth monoantimonides RSb (R = Y, Ce, Gd, Dy, Ho, Tm, Lu). The experimentally measured Fermi surface (FS) of RSb consists of at least two concentric hole pockets at the Γ point and two intersecting electron pockets at the X point. These data agree relatively well with the electronic structure calculations. Detailed photon energy dependence measurements using both synchrotron and laser ARPES systems indicate that there is at least one Fermi surface sheet with strong three-dimensionality centered at the Γ point. Due to the "lanthanide contraction", the unit cell of different rare-earth monoantimonides shrinks when changing the rare-earth ion from CeSb to LuSb. This results in the differences in the chemical potentials in these compounds, which are demonstrated by both ARPES measurements and electronic structure calculations. Interestingly, in CeSb, the intersecting electron pockets at the X point seem to be touching the valence bands, forming a fourfold-degenerate Dirac-like feature. On the other hand, the remaining rare-earth monoantimonides show significant gaps between the upper and lower bands at the X point. Furthermore, similar to the previously reported results of LaBi, a Dirac-like structure was observed at the Γ point in YSb, CeSb, and GdSb, compounds showing relatively high magnetoresistance. This Dirac-like structure may contribute to the unusually large magnetoresistance in these compounds.

  1. Point defect balance in epitaxial GaSb

    Energy Technology Data Exchange (ETDEWEB)

    Segercrantz, N., E-mail: natalie.segercrantz@aalto.fi; Slotte, J.; Makkonen, I.; Kujala, J.; Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 14100, FIN-00076 Aalto Espoo (Finland); Song, Y.; Wang, S. [Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Göteborg (Sweden); State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences 865 Changning Road, Shanghai 200050 (China)

    2014-08-25

    Positron annihilation spectroscopy in both conventional and coincidence Doppler broadening mode is used for studying the effect of growth conditions on the point defect balance in GaSb:Bi epitaxial layers grown by molecular beam epitaxy. Positron annihilation characteristics in GaSb are also calculated using density functional theory and compared to experimental results. We conclude that while the main positron trapping defect in bulk samples is the Ga antisite, the Ga vacancy is the most prominent trap in the samples grown by molecular beam epitaxy. The results suggest that the p–type conductivity is caused by different defects in GaSb grown with different methods.

  2. [Direct determination of selenium and bismuth in antimony and antimony compound by hydride generation-atomic fluorescence spectrometry].

    Science.gov (United States)

    Li, Z X; Tong, K Y; Guo, X W

    2001-10-01

    The interference of Sb in determination of Se and Bi in antimony powder and antimony compound has been studied in different acidity, it is found that the interference of antimony has been reduced apparently in high acidity. Simultaneously, according to the difference of hydride generation reaction between Sb5+ and Sb3+, a sensitive and rapid method has been developed and used to determine Se and Bi in real samples. The recovery of the method is 95%-105% for practical samples. Detection limits are 0.00004 x 10(-2) (content) for Se and 0.0001 x 10(-2) mg.L-1 (content) for Bi respectively. The relative standard deviations of Se are 2.4% (content = 0.00169 x 10(-2) mg.L-1) and 5.4% (content = 0.00056 x 10(-2) mg.L-1). The relative standard deviations of Bi are 5.0% (content = 0.00024 x 10(-2) mg.L-1) and 1.3% (content = 0.00229 x 10(-2) mg.L-1). The method has been applied to determination of Se and Bi in practical samples with satisfactory results.

  3. Bismuth-induced restructuring of the GaSb(110) surface

    DEFF Research Database (Denmark)

    Gemmeren, T. van; Lottermoser, L.; Falkenberg, G.

    1998-01-01

    The structure of the GaSb(110)(1 x 2)-Bi reconstruction has been solved using surface x-ray diffraction, scanning tunneling microscopy, and photoelectron spectroscopy. The ideal GaSb(110) surface is terminated with zigzag chains of anions and cations running in the [1 (1) over bar 0] direction. I...

  4. Forced convection by Inclined Rotary Bridgman method for growth of CoSb3 and FeSb2 single crystals from Sb-rich solutions

    Science.gov (United States)

    Pillaca, Mirtha; Harder, Oliver; Miller, Wolfram; Gille, Peter

    2017-10-01

    Sb-based compounds such as CoSb3 and FeSb2 are interesting materials for thermoelectric applications. Their single crystal growth can be achieved from high-temperature solutions that are strongly enriched in Sb. In Bridgman growth using closed ampoules, effective mixing of the solution is an important prerequisite in order to minimize the high risk of liquid inclusion formation. We have successfully grown inclusion-free single crystal of CoSb3 and FeSb2 by rotating the ampoule in a Bridgman-type crystal growth set-up being inclined by 75° with respect to the vector of gravity. Numerical modelling as well as experimental growth studies have demonstrated the strong influence of forced convection that is achieved by this modified directional solidification technique called Inclined Rotary Bridgman method.

  5. Preparation and properties of organo(acetylacetonato)antimony(V) compounds

    NARCIS (Netherlands)

    Meinema, H.A.; Noltes, J.G.

    Organo(acetylacetonato)antimony(V) compounds of the types R2SbCl2Acac, R4SbAcac, PhSbCl3Acac and Cl4SbAcac have been synthesized. The compounds are monomeric in solution. IR and PMR data of these compounds, which contain a chelated Acac ligand have been discussed. Ph2SbCl2Acac shows abnormal

  6. Structure and properties of intermetallic ternary rare earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Casper, Frederick

    2008-12-17

    The so called material science is an always growing field in modern research. For the development of new materials not only the experimental characterization but also theoretical calculation of the electronic structure plays an important role. A class of compounds that has attracted a great deal of attention in recent years is known as REME compounds. These compounds are often referred to with RE designating rare earth, actinide or an element from group 1-4, M representing a late transition metal from groups 8-12, and E belonging to groups 13-15. There are more than 2000 compounds with 1:1:1 stoichiometry belonging to this class of compounds and they offer a broad variety of different structure types. Although many REME compounds are know to exist, mainly only structure and magnetism has been determined for these compounds. In particular, in the field of electronic and transport properties relatively few efforts have been made. The main focus in this study is on compounds crystallizing in MgAgAs and LiGaGe structure. Both structures can only be found among 18 valence electron compounds. The f electrons are localized and therefor not count as valence electrons. A special focus here was also on the magnetoresistance effects and spintronic properties found among the REME compounds. An examination of the following compounds was made: GdAuE (E=In,Cd,Mg), GdPdSb, GdNiSb, REAuSn (RE=Gd,Er,Tm) and RENiBi (RE=Pr,Sm,Gd-Tm,Lu). The experimental results were compared with theoretic band structure calculations. The first half metallic ferromagnet with LiGaGe structure (GdPdSb) was found. All semiconducting REME compounds with MgAgAs structure show giant magnetoresistance (GMR) at low temperatures. The GMR is related to a metal-insulator transition, and the value of the GMR depends on the value of the spin-orbit coupling. Inhomogeneous DyNiBi samples show a small positive MR at low temperature that depends on the amount of metallic impurities. At higher fields the samples show a

  7. Polynuclear Bismuth Oxido Sulfonato Clusters, Polymers, and Ion Pairs from Bi2O3 under Mild Conditions.

    Science.gov (United States)

    Senevirathna, Dimuthu C; Blair, Victoria L; Werrett, Melissa V; Andrews, Philip C

    2016-11-07

    Eight novel bismuth(III) sulfonato compounds have been synthesized and characterized using the sonochemical reaction of Bi2O3 with a range of sulfonic acids, including 2,5-dimethylbenzenesulfonic acid (2,5-DMSH), 2,4-dinitrobenzenesulfonic acid (2,4-DNSH), 2,5-dichlorobenzenesulfonic acid (2,5-DCSH), 1,2-benzenedisulfonic acid (1,2-BDSH2), 1,3-benzenedisulfonic acid (1,3-BDSH2), 2-sulfobenzoic acid (2-SBH2), 3-sulfobenzoic acid (3-SBH2), and 2-naphthalenesulfonic acid (NPSH). Six of the complexes (1, 2, 4, and 6-8) were structurally characterized through single-crystal X-ray crystallography. In the presence of the monosulfonic acids 2,5-DMSH, 2,4-DNSH, and 2,5-DCSH, polynuclear bismuth(III) oxido clusters were isolated: namely, [Bi6O4(OH)4(2,5-DMS)6(H2O)6]·10H2O (1·10H2O), [Bi6O4(OH)4(2,4-DNS)6(H2O)6]·6H2O (2·6H2O), and [Bi6O4(OH)4(2,5-DCS)6(H2O)6] (3). The disulfonic acid 1,3-BDSH2 also produced an oxido cluster: [Bi6O4(OH)4(1,3-BDS)3]·8H2O (5·8H2O). The remaining diacid ligands (1,2-BDSH2, 2-SBH2, and 3-SBH2), upon reaction with Bi2O3, produced polymeric Bi(III) sulfonato complexes: namely [Bi(1,2-BDS)(OH)(H2O)2]∞ (4), [Bi(2-SB)(2-SBH)H2O]∞·2H2O (6·2H2O), and [NH2(Me)2]2[Bi2(3-SB)4]∞ (7). The larger NPSH ligand produced the monomeric contact ion pair [Bi(NPS)2(H2O)6][NPS]·3H2O (8·3H2O), upon sonication with Bi2O3.

  8. Crystal structure of Ba5In4Sb6

    Directory of Open Access Journals (Sweden)

    Ming-Yan Pan

    2015-05-01

    Full Text Available The title compound, pentabarium tetraindium hexaantimony, was synthesized by an indium-flux reaction and its structure features layers composed of edge-sharing In2Sb6 units. The voids between the In4Sb6 layers are filled by Ba2+ cations, which are all surrounded by six Sb atoms and form bicapped octahedral or triangular prismatic coordination geometries. There are five barium ions in the asymmetric unit: one has no imposed crystallographic symmetry, two lie on mirror planes and two have mm2 point symmetry. The two In atoms and four Sb atoms in the asymmetric unit all lie on general crystallographic positions.

  9. Crystal structure, ionic conductivity and dielectric relaxation studies in the (C{sub 5}H{sub 10}N){sub 2}BiBr{sub 5} compound

    Energy Technology Data Exchange (ETDEWEB)

    Masmoudi, W., E-mail: masmoudiwafa1@yahoo.fr [Unite de Recherche de Chimie Industrielle et Materiaux, ENIS, BP 1173, Sfax (Tunisia); Kamoun, S.; Ayedi, H.F. [Unite de Recherche de Chimie Industrielle et Materiaux, ENIS, BP 1173, Sfax (Tunisia); Guidara, K. [Laboratoire de l' Etat Solide, Faculte des Sciences de Sfax 3018, Sfax (Tunisia)

    2012-07-01

    The synthesis and crystal structure of the bis (3-dimethylammonium-1-propyne) pentabromobismuthate(III) salt are given in the present paper. After an X-ray investigation, it has been shown that the title compound crystallizes at 298 K in a centrosymmetric monoclinic system, in the space group C{sub 2}/c with the following lattice parameters a=12.9034(3) A, b=19.4505(6) A, c=8.5188(2) A, {beta}=102.449(2). Not only were the impedance spectroscopy measurements of (C{sub 5}H{sub 10}N){sub 2}BiBr{sub 5} carried out from 209 Hz to 5 MHz over the temperature range of 318 K-373 K, but also its ac conductivity evaluated. Besides, the dielectric relaxation was examined using the modulus formalism. Actually, the near values of activation energies obtained from the impedance and modulus spectra confirms that the transport is of an ion hopping mechanism, dominated by the motion of the H{sup +} ions in the structure of the investigated material.

  10. Composition- and crystallinity-dependent thermoelectric properties of ternary BixSb2-xTey films

    Science.gov (United States)

    Kim, Jiwon; Lim, Jae-Hong; Myung, Nosang V.

    2018-01-01

    BixSb2-xTey films with controlled compositions were synthesized by a simple and cost-effective electrodeposition technique followed by post-annealing, for thermoelectric applications. Tailoring the chemical composition of ternary BixSb2-xTey materials is critical to adjust the carrier concentration and carrier type, which are crucial to determine their thermoelectric performance. Herein, the composition of electrodeposited BixSb2-xTey film was simply tailored by controlling the [Sb]/[Bi] ratio in the electrolytes while maintaining their dense and uniform morphology. Crystallographic properties of the BixSb2-xTey films, such as crystallinity and grain size changes, were confirmed by X-ray diffraction. Room-temperature measurements of electrical conductivity, Hall mobility, and carrier concentration revealed that the substitution of Bi with Sb decreased the carrier concentration, and increased the mobility. The Seebeck coefficient of the ternary BixSb2-xTey films transitioned between p- and n-type characteristics with an increase in the Bi content. Moreover, the mobility-dependent electrical conductivity of the Bi10Sb30Te60 film resulted in a high Seebeck coefficient owing to decreased carrier concentration of the film, leading to a power factor (PF) of ∼490 μW/m K2. This is more than 10 times higher than the PF values of binary nanocrystalline Sb2Te3 films.

  11. Magnetic and thermodynamic properties of the lightly electron-doped manganite compound (Ca,Sr)Mn{sub 0.95}Sb{sub 0.05}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Takahiro [Department of Materials Science and Engineering, Iwate University, Morioka 020-8551 (Japan); Matsukawa, Michiaki, E-mail: matsukawa@iwate-u.ac.jp [Department of Materials Science and Engineering, Iwate University, Morioka 020-8551 (Japan); Aoyagi, Takahiro; Kobayashi, Satoru; Taniguchi, Haruka [Department of Materials Science and Engineering, Iwate University, Morioka 020-8551 (Japan); Nimori, Shigeki [National Institute for Materials Science, Tsukuba 305-0047,Japan (Japan); Suryanarayanan, Ramanathan [Laboratoire de Physico-Chimie de L' état Solide, CNRS, UMR8182, Université Paris-Sud, 91405 Orsay (France)

    2015-03-15

    We report on the dc magnetization and ac magnetic susceptibility of the lightly electron-doped manganite compound (Ca{sub 1−x}{sup 2+}Sr{sub x}{sup 2+})Mn{sub 0.9}{sup 4+}Mn{sub 0.05}{sup 3+}Sb{sub 0.05}{sup 5+}O{sub 3}{sup 2−} (x=0.0, 0.05, 0.10, 0.15, 0.16, 0.17, and 0.2) with a fixed carrier content, to examine the effect of chemical pressure on magnetization reversal of this system. In a weak magnetic-field-cooled measurement, diamagnetic magnetization is observed for x≤15%, which changes to positive values for x>15%. We present a magnetic phase diagram as a function of Sr concentration in several magnetic fields. The ac magnetic susceptibility measurement indicates the existence of magnetic frustration for the Sr substituted samples exhibiting diamagnetic behavior. To better understand the thermodynamic properties of this system, we have measured the specific heat as a function of temperature over a field cooling of 100 Oe. Our data show no anomalies associated with the temperature-dependent magnetization reversal, indicating the absence of long-range magnetic ordering. - Highlights: • We demonstrate the effect of chemical pressure on the magnetic and thermal properties of the lightly electron-doped manganite compound. • The thermodynamic measurements exhibit no magnetic phase transition associated with the magnetization reversal. • The ac magnetic susceptibility data strongly indicate the existence of magnetic frustration between diamagnetic clusters and canted AFM matrix.

  12. The oxygen content of the high-temperature superconducting compound Bi{sub 2+x}Sr{sub 3-y}CayCu{sub 2}O{sub 8+d} with respect to varying Ca and Bi contents

    Energy Technology Data Exchange (ETDEWEB)

    Majewski, P.; Su, H.L.; Aldinger, F. [Max-Planck-Institut fuer Metallforschung, Stuggart (Germany)

    1994-12-31

    The oxygen content of Bi{sub 2+x}Sr{sub 3-y}Ca{sub y}Cu{sub 2}O{sub 8+d} (2212 phase) has been determined as a function of its cation concentration. With increasing Ca and Bi content the oxygen content increases and T{sub c} decreases. The oxygen content of Ca rich 2212 phase increases with decreasing annealing temperatures. The study shows that the T{sub c} of the 2212 phase primarily is controlled by its cation concentration.

  13. Hard and soft X-ray spectroscopy of Sm-based heavy-fermion compounds SmFe{sub 4} P{sub 12} and SmOs{sub 4} Sb{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, A. [Department of Physics, Faculty of Science and Engineering, Konan University, Kobe 658-8501 (Japan)], E-mail: yamasaki@konan-u.ac.jp; Imada, S.; Higashimichi, H.; Fujiwara, H.; Saita, T.; Miyamachi, T.; Sekiyama, A. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Sugawara, H. [Graduate School of Human and Natural Environment Science, University of Tokushima, Tokushima 770-8502 (Japan); Kikuchi, D.; Sato, H. [Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 (Japan); Higashiya, A. [RIKEN, Mikazuki, Sayo, Hyogo 679-5148 (Japan); Yabashi, M. [Japan Synchrotron Research Institute, Mikazuki, Sayo, Hyogo 679-5198 (Japan); Tamasaku, K.; Miwa, D.; Ishikawa, T. [RIKEN, Mikazuki, Sayo, Hyogo 679-5148 (Japan); Suga, S. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2007-05-15

    We have carried out soft and hard X-ray spectroscopy of Sm-based filled skutterudites SmFe{sub 4} P{sub 12} and SmOs{sub 4} Sb{sub 12}. Sm 3d-4f resonant photoemission and Sm 3d-4f X-ray absorption spectra suggest that SmOs{sub 4} Sb{sub 12} has much more strongly mixed Sm valence state than SmFe{sub 4} P{sub 12} in the bulk. On the other hand, the Sm trivalent state is dominant on the surface of SmOs{sub 4} Sb{sub 12}.

  14. Antiferromagnetism in semiconducting SrMn2Sb2 and BaMn2Sb2 single crystals

    Science.gov (United States)

    Sangeetha, N. S.; Smetana, V.; Mudring, A.-V.; Johnston, D. C.

    2018-01-01

    Crystals of SrMn2Sb2 and BaMn2Sb2 were grown using Sn flux and characterized by powder and single-crystal x-ray diffraction, respectively, and by single-crystal electrical resistivity ρ , heat capacity Cp, and magnetic susceptibility χ measurements versus temperature T , and magnetization versus field M (H ) isotherm measurements. SrMn2Sb2 adopts the trigonal CaAl2Si2 -type structure, whereas BaMn2Sb2 crystallizes in the tetragonal ThCr2Si2 -type structure. The ρ (T ) data indicate semiconducting behaviors for both compounds with activation energies of ≳0.35 eV for SrMn2Sb2 and 0.16 eV for BaMn2Sb2 . The χ (T ) and Cp(T ) data reveal antiferromagnetic (AFM) ordering at TN = 110 K for SrMn2Sb2 and 450 K for BaMn2Sb2 . The anisotropic χ (T ≤TN) data also show that the ordered moments in SrMn2Sb2 are aligned in the hexagonal a b plane, whereas the ordered moments in BaMn2Sb2 are aligned collinearly along the tetragonal c axis. The a b -plane M (H ) data for SrMn2Sb2 exhibit a continuous metamagnetic transition at low fields 0 literature for Mn pnictides with the CaAl2Si2 and ThCr2Si2 crystal structures show that the TN values for the CaAl2Si2 -type compounds are much smaller than those for the ThCr2Si2 -type materials.

  15. Manifestation of hopping conductivity and granularity within phase diagrams of LaO1-x F x BiS2, Sr1-x La x FBiS2 and related BiS2-based compounds

    Science.gov (United States)

    Arouca, R.; Silva Neto, M. B.; Chaves, C. M.; Nagao, M.; Watauchi, S.; Tanaka, I.; ElMassalami, M.

    2017-09-01

    Layered BiS 2 -based series, such as LaO 1-x F x BiS 2 and Sr 1-x La x FBiS 2 , offer ideal examples for studying normal and superconducting phase diagram of a solid solution that evolves from a nonmagnetic band-insulator parent. We constructed typical x-T phase diagrams of these systems based on events occurring in thermal evolution of their electrical resistivity, ρ(x, T) . Overall evolution of these diagrams can be rationalized in terms of (i) Mott-Efros-Shklovskii scenario which, within the semiconducting x regime (x_MIT = Mott metal-insulator transition), describes the doping influence on the thermally activated hopping conductivity. (ii) A granular metal (superconductor) scenario which, within x_MITpressure or heat treatment.

  16. Superconductivity induced by external pressure in Eu3-x Sr x Bi2S4F4 (x = 1, 2) compounds

    Science.gov (United States)

    Kannan, M.; Kalai Selvan, G.; Haque, Z.; Thakur, Gohil S.; Wang, B.; Ishigaki, K.; Uwatoko, Y.; Gupta, L. C.; Ganguli, A. K.; Arumugam, S.

    2017-11-01

    We have studied the temperature-pressure phase diagram of two materials Eu3-x Sr x Bi2S4F4 (x = 1 and x = 2) by electrical resistivity and magnetic measurements down to 2 K. Semiconducting resistive behavior observed in both the materials under ambient conditions transforms into metallic behavior as externally applied pressure gradually increases. Superconductivity is observed in both the materials at and above applied pressure P = 2.37 GPa. Under the highest pressure P ˜ 2.9 GPa applied in our measurements, T c is ˜9.8 K in Eu2SrBi2S4F4 (x = 1) and 8.2 K in EuSr2Bi2S4F4 (x = 2). Upper critical field H c2(0) ˜ 3.04 T (x = 1) and 1.17 T (x = 2) is estimated from magnetic field dependent resistivity measurements at 2.9 GPa. Using the Arrhenius equation, we estimate the thermally activated flux flow activation energy U 0 as 116 K in Eu2SrBi2S4F4 and 39 K in EuSr2Bi2S4F4. At 2 K, DC magnetic susceptibility measurements indicate S-type paramagnetic behavior.

  17. The antimony-group 11 chemical bond: dissociation energies of the diatomic molecules CuSb, AgSb, and AuSb.

    Science.gov (United States)

    Carta, V; Ciccioli, A; Gigli, G

    2014-02-14

    The intermetallic molecules CuSb, AgSb, and AuSb were identified in the effusive molecular beam produced at high temperature under equilibrium conditions in a double-cell-like Knudsen source. Several gaseous equilibria involving these species were studied by mass spectrometry as a function of temperature in the overall range 1349-1822 K, and the strength of the chemical bond formed between antimony and the group 11 metals was for the first time measured deriving the following thermochemical dissociation energies (D°(0), kJ/mol): 186.7 ± 5.1 (CuSb), 156.3 ± 4.9 (AgSb), 241.3 ± 5.8 (AuSb). The three species were also investigated computationally at the coupled cluster level with single, double, and noniterative quasiperturbative triple excitations (CCSD(T)). The spectroscopic parameters were calculated from the potential energy curves and the dissociation energies were evaluated at the Complete Basis Set limit, resulting in an overall good agreement with experimental values. An approximate evaluation of the spin-orbit effect was also performed. CCSD(T) calculations were further extended to the corresponding group 11 arsenide species which are here studied for the first time and the following dissociation energies (D°(0), kJ/mol): 190 ± 10 (CuAs), 151 ± 10 (AgAs), 240 ± 15 (AuAs) are proposed. Taking advantage of the new experimental and computational information here presented, the bond energy trends along group 11 and 4th and 5th periods of the periodic table were analyzed and the bond energies of the diatomic species CuBi and AuBi, yet experimentally unobserved, were predicted on an empirical basis.

  18. Synthesis, crystal structure, thermal analysis and dielectric properties of [(C{sub 4}H{sub 9}){sub 4}N]{sub 3}Bi{sub 2}Cl{sub 9} compound

    Energy Technology Data Exchange (ETDEWEB)

    Trigui, W., E-mail: walatrigui@yahoo.fr; Oueslati, A.; Chaabane, I.; Hlel, F.

    2015-07-15

    A new organic–inorganic tri-tetrabutylammonium nonachlorobibismuthate(III) compound was prepared. It was found to crystallize in the monoclinic system (P2{sub 1}/n space group) with the following lattice parameters: a=11.32(2) Å, b=22.30(3) Å, c=28.53(2) Å and β=96.52(0)°. The [Bi{sub 2}Cl{sub 9}]{sup 3−} anions are surrounded by six [(C{sub 4}H{sub 9})N]{sup +} cations, forming an octahedral configuration. These octahedra are sharing corners in order to provide the tri-dimensional network cohesion. The differential scanning calorimetry reveals four order-disorder reversible phase transitions located at 214, 238, 434 and 477 K. The Raman and infrared spectra confirm the presence of both cationic [(C{sub 4}H{sub 9})N]{sup +} and anionic [Bi{sub 2}Cl{sub 9}]{sup 3−} parts. The dielectric parameters, real and imaginary dielectric permittivity (ε′ and ε″), and dielectric loss tangent (tg δ), were measured in the frequency range of 209 kHz–5 MHz at different temperatures. The variations of dielectric dispersion (ε') and dielectric absorption (ε″) with frequency show a distribution of relaxation times, which is probably related to the change in the dynamical state of the [(C{sub 4}H{sub 9}){sub 4}N]{sup +} cations and the [Bi{sub 2}Cl{sub 9}]{sup 3−} anions. - Graphical abstract: Projection of the atomic arrangement of the [(C{sub 4}H{sub 9}){sub 4}N]{sub 3}Bi{sub 2}Cl{sub 9} compound along the b axis. - Highlights: • The structure of the (TBA){sub 3}Bi{sub 2}Cl{sub 9} compound was solved and reported. • The cristal belongs to the monoclinic system with P2{sub 1}/n space group. • DSC discloses four order–disorder reversible phases transitions. • The temperature-dependent permittivity ε' and ε″ has been investigated.

  19. The effect of lanthanides on color properties of the (Bi2O30.7(Ln2O30.3 compounds

    Directory of Open Access Journals (Sweden)

    Šulcová P.

    2008-01-01

    Full Text Available (Bi2O30.7(Ln2O30,3 solid solutions were synthesized as new inorganic yellow and orange pigments and their color properties have been investigated as possible ecological materials. The pigments were prepared by the solid state reaction of mixed oxides (Bi2O30.7(Ln2O30.3 of various rare earth cations (Ln = Eu, Gd, Tm, Yb and Lu. All the synthesized pigment samples were found to have color coordinates, low a* and high b* and exhibit the color from pale light yellow to orange. Reflectance spectra of the samples show high reflectance percentage in the 600 - 700 nm range. Characterization of the (Bi2O30.7(Ln2O30,3 solid solutions suggests that they have a potential to be alternative yellow colorants for paints, inks, plastics, and ceramics.

  20. Growth and thermoelectric properties of FeSb2 films produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Sun, Ye; Canulescu, Stela; Sun, Peijie

    2011-01-01

    Thermoelectric FeSb2 films were produced by pulsed laser deposition on silica substrates in a low-pressure Ar environment. The growth conditions for near phase-pure FeSb2 films were confirmed to be optimized at a substrate temperature of 425°C, an Ar pressure of 2 Pa, and deposition time of 3 h b...... by ablating specifically prepared compound targets made of Fe and Sb powders in atomic ratio of 1:4. The thermoelectric transport properties of FeSb2 films were investigated. Pulsed laser deposition was demonstrated as a method for production of good-quality FeSb2 films....

  1. Breakdown of half-metallic ferromagnetism in zinc-blende II-V compounds: First-principles calculations

    Science.gov (United States)

    Li, Yun; Yu, Jaejun

    2008-10-01

    We investigated the electronic and magnetic properties of a series of zinc-blend II-V compounds by carrying out density-functional theory calculations including spin-orbit couplings. Contrary to the case of CaN and CaP, the half-metallic characteristics of the II-V compounds such as CaBi were found to be destroyed. Our analysis of the valence-band structures of CaAs, CaSb, and CaBi revealed a critical role of the spin-orbit coupling interactions on the exchange-split band structure, thereby leading to breakdown of the half-metallic ferromagnetism for the systems with heavier group V elements in the zinc-blend II-V compounds.

  2. Synthesis and structural characterization of a novel Sillén - Aurivillius bismuth oxyhalide, PbBi3VO7.5Cl, and its derivatives

    Science.gov (United States)

    Charkin, Dmitri O.; Plokhikh, Igor V.; Kazakov, Sergey M.; Kalmykov, Stepan N.; Akinfiev, Victor S.; Gorbachev, Anatoly V.; Batuk, Maria; Abakumov, Artem M.; Teterin, Yury A.; Maslakov, Konstantin I.; Teterin, Anton Yu; Ivanov, Kirill E.

    2018-01-01

    A new Sillén - Aurivillius family of layered bismuth oxyhalides has been designed and successfully constructed on the basis of PbBiO2X (X = halogen) synthetic perites and γ-form of Bi2VO5.5 solid electrolyte. This demonstrates, for the first time, the ability of the latter to serve as a building block in construction of mixed-layer structures. The parent compound PbBi3VO7.5-δCl (δ ≤ 0.05) has been investigated by powder XRD, TEM, XPS methods and magnetic susceptibility measurements. An unexpected but important condition for the formation of the mixed-layer structure is partial (ca. 5%) reduction of VV into VIV which probably suppresses competitive formation of apatite-like Pb - Bi vanadates. This reduction also stabilizes the γ polymorphic form of Bi2VO5.5 not only in the intergrowth structure, but in Bi2V1-xMxO5.5-y (M = Nb, Sb) solid solutions.

  3. First-principles calculation of semiclassical thermoelectric properties of (AgSbSe{sub 2}){sub n}(AgSbTe{sub 2}){sub n} superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Salimi, Marzieh [Department of Physics, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Hashemifar, S. Javad, E-mail: hashemifar@cc.iut.ac.ir [Department of Physics, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Nanotechnology and Advanced Materials Institute, Isfahan University of Technology (Iran, Islamic Republic of)

    2015-11-25

    In this research, we perform density functional – pseudo potential calculation within generalized gradient approximation (GGA) to investigate semiclassical thermoelectric properties of (AgSbSe{sub 2}){sub n}(AgSbTe{sub 2}){sub n} (n = 1,2) thin film superlattices. It is seen that GGA, GGA + U, and the modified Becke Johnson (mBJ) functionals as well as full-relativistic corrections are not able to describe properly the electronic structure of bulk AgSbSe{sub 2} and AgSbTe{sub 2}, hence a scissor correction is used throughout this study. The Seebeck coefficient, electrical conductivity, and electronic part of the thermal conductivity of bulk compounds as well as superlattices are computed at different values of hole doping, in the fixed relaxation time approximation. It is argued that the (AgSbSe{sub 2}){sub 1}(AgSbTe{sub 2}){sub 1} superlattice may exhibits improved Seebeck coefficient compared with the bulk compounds and (AgSbSe{sub 2}){sub 2}(AgSbTe{sub 2}){sub 2} superlattice. - Highlights: • Ab initio study of (AgSbTe2)/(AgSbSe2) superlattice as a new thermoelectric system. • Computing Seebeck coefficient and power factor in relaxation time approximation. • Stable structure of the superlattices is determined. • Thermoelectric parameters of the superlattices are compared with the bulk materials.

  4. Synthesis of new (Bi, La) 3MSb2O11 phases (M= Cr, Mn, Fe) with ...

    Indian Academy of Sciences (India)

    The magnetic measurements on Bi2LaCrSb2O11 and Bi2LaMnSb2O11 show paramagnetic behaviour with magnetic moments close to the expected spin only magnetic moments of Cr+3 and Mn+3. The UV-Visible diffuse reflectance spectra are broad and indicate that these materials possess a bandgap of ∼ 2 eV.

  5. Novel use of BiOCl as an efficient and selective reagent for cleavage of 2,4-dinitrophenylhydrazones to carbonyl compounds

    Directory of Open Access Journals (Sweden)

    Manesh Abbas Amini

    2016-01-01

    Full Text Available A novel use of bismuth oxychloride (BiOCl as an efficient and selective oxidative catalyst for the clean cleavage of 2,4-dinitrophenyl-hydrazones under mild conditions is reported. The reactions proceed very smoothly, and the yields are good to excellent. Over oxidation of aldehydes to carboxylic acid and the formation of by-products were not observed. The catalyst could be recovered and reused for at least four reaction cycles without considerable loss of reactivity.

  6. Superconductivity up to 114 K in the Bi-Al-Ca-Sr-Cu-O compound system without rare-earth elements

    Science.gov (United States)

    Chu, C. W.; Bechtold, J.; Gao, L.; Hor, P. H.; Huang, Z. J.

    1988-01-01

    Stable superconductivity up to 114 K has been reproducibly detected in Bi-Al-Ca-Sr-Cu-O multiphase systems without any rare-earth elements. Pressure has only a slight positive effect on T(c). These observations provide an extra material base for the study of the mechanism of high-temperature superconductivity and also the prospect of reduced material cost for future applications of superconductivity.

  7. Bulk Superconductivity Induced by Se Substitution in BiCh2-Based Layered Compounds Eu0.5Ce0.5FBiS2-xSex

    Science.gov (United States)

    Goto, Yosuke; Sogabe, Ryota; Mizuguchi, Yoshikazu

    2017-10-01

    We report the effect of Se substitution on the crystal structure and superconductivity of BiCh2-based (Ch: S, Se) layered compounds Eu0.5Ce0.5FBiS2-xSex (x = 0-1). Crystal structure analysis showed that both lattice constants, a and c, increased with increasing x, which is different from the related La-doped system Eu0.5La0.5FBiS2-xSex. This is due to Se substitution at both in-plane and out-of-plane Ch sites in the present Ce-doped system. Zero resistivity was observed for x = 0.2-1 above 2 K. The superconducting properties of Eu0.5Ce0.5FBiS2-xSex were investigated by magnetic susceptibility measurement, and the highest superconducting transition temperature of 3.5 K was obtained for x = 0.6 with a large shielding volume fraction. The emergence of bulk superconductivity and metallic conductivity can be qualitatively described in terms of the increased in-plane chemical pressure effect. A magnetic anomaly below 8 K, probably because of the ferromagnetic order of the magnetic moment of Ce3+ ions, coexists with bulk superconductivity in the BiCh2 layer. Since the effect of Se substitution on the magnetic transition temperature is ignorable, we suggest that the coupling between the magnetic order at the (Eu,Ce)F layer and the superconductivity at the Bi(S,Se)2 layer is weak.

  8. Role of interlayer coupling for the power factor of CuSbS2 and CuSbSe2

    KAUST Repository

    Alsaleh, Najebah Mohammed Abdullah

    2017-01-08

    The electronic and transport properties of bulk and monolayer CuSbS2 and CuSbSe2 are determined by using density functional theory and semiclassical Boltzmann transport theory, in order to investigate the role of interlayer coupling for the thermoelectric properties. The calculated band gaps of the bulk compounds are in agreement with experiments and significantly higher than those of the monolayers, which thus show lower Seebeck coefficients. Since also the electrical conductivity is lower, the monolayers are characterized by lower power factors. Therefore, interlayer coupling is found to be essential for the excellent thermoelectric response of CuSbS2 and CuSbSe2, even though it is weak.

  9. Role of interlayer coupling for the power factor of CuSbS2 and CuSbSe2

    KAUST Repository

    Alsaleh, Najebah M.

    2016-09-26

    The electronic and transport properties of bulk and monolayer CuSbS2 and CuSbSe2 are determined by using density functional theory and semiclassical Boltzmann transport theory, in order to investigate the role of interlayer coupling for the thermoelectric properties. The calculated band gaps of the bulk compounds are in agreement with experiments and significantly higher than those of the monolayers, which thus show lower Seebeck coefficients. Since also the electrical conductivity is lower, the monolayers are characterized by lower power factors. Therefore, interlayer coupling is found to be essential for the excellent thermoelectric response of CuSbS2 and CuSbSe2, even though it is weak.

  10. Unusual Phase Diagram of CeOs4Sb12

    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 MT4X12, 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 CeOs4Sb12, PrOs4Sb12, and NdOs4Sb12, 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 CeOs4Sb12.

  11. Atomic structure of the SbCu surface alloy: A surface X-ray diffraction study

    DEFF Research Database (Denmark)

    Meunier, I.; Gay, J.M.; Lapena, L.

    1999-01-01

    The dissolution at 400 degrees C of an antimony layer deposited at room temperature on a Cu(111) substrate leads to a surface alloy with a p(root 3x root 3)R 30 degrees x 30 degrees superstructure and a Sb composition of 1/3.We present here a structural study of this Sb-Cu compound by surface X...

  12. Study of the yttrium and zinc substitutions effects in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} compounds by transport measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pignon, B. [Laboratoire d' Electrodynamique des Materiaux Avances, UMR 6157 CNRS-CEA, Universite Francois Rabelais, Faculte des Sciences et Techniques, Parc de Grandmont, 37200 Tours (France)], E-mail: pignon@univ-tours.fr; Autret-Lambert, C.; Ruyter, A. [Laboratoire d' Electrodynamique des Materiaux Avances, UMR 6157 CNRS-CEA, Universite Francois Rabelais, Faculte des Sciences et Techniques, Parc de Grandmont, 37200 Tours (France); Decourt, R.; Bassat, J.M. [Institut de Chimie de la Matiere Condensee de Bordeaux, UPR 9048 CNRS, Universite de Bordeaux I, 87 Av. du Dr Schweizer, 33608 Pessac cedex (France); Monot-Laffez, I.; Ammor, L. [Laboratoire d' Electrodynamique des Materiaux Avances, UMR 6157 CNRS-CEA, Universite Francois Rabelais, Faculte des Sciences et Techniques, Parc de Grandmont, 37200 Tours (France)

    2008-06-15

    The effects of yttrium Y and zinc Zn substitution on calcium Ca and cupper Cu sites in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} compounds have been investigated by resistivity measurements. At high temperature, after a superconducting transition, the electrical behaviour evolves from a metallic state in compounds with a weak Y concentration into a semi-conducting state (hopping conduction) in compounds with a large Y concentration. Similarly, the Zn substitution modifies the electrical behaviour from metallic to insulating with a much lower concentration comparatively to Y. In the two cases, the semi-conducting behaviour is described by hopping between localised states in the conduction band. This localization is explained by the random distribution of the doping elements which originates from the Y/Zn and Cu wave-functions overlap. The obtained results show the localization is improved in the case of Zn. Consequently, it is suggested that the direct substitution of Zn into the planes leads to a greater overlap. Moreover, the superconducting transition (critical temperature: T{sub C}) shows an irregular depression when Zn is substituted. According to an X-Ray diffraction study, this result can be interpreted by internal micro-strains in the structure.

  13. Hydrothermal synthesis and crystal structure analysis of two new cadmium bismuthates, CdBi2O6 and Cd0.37Bi0.63O1.79

    Directory of Open Access Journals (Sweden)

    N. Kumada

    2015-09-01

    Full Text Available Two new cadmium bismuthates, CdBi2O6 and Cd0.37Bi0.63O1.79, were prepared by hydrothermal reaction using NaBiO3·nH2O as one of the starting compounds. The crystal structures of these compounds were refined by using synchrotron X-ray powder diffraction data. The former bismuthate has a MnSb2O6-type structure with a hexagonal cell (space group: P321; the cell parameters were a = 9.3641(7 and c = 4.9523(3 Å, and the final R-factors were Rwp = 4.59% and Rp = 3.04%. The latter bismuthate has a fluorite-type structure with a cubic cell (space group: Fm3¯m of a = 5.4110(4 Å, and the final R-factors were Rwp = 4.79% and Rp = 3.57%. These new bismuthates exhibit no photocatalytic activity under visible light.

  14. Crystal growth and characterization of the dilutable frustrated spin-ladder compound Bi(Cu 1- xZn x) 2PO 6

    Science.gov (United States)

    Wang, S.; Pomjakushina, E.; Shiroka, T.; Deng, G.; Nikseresht, N.; Rüegg, Ch.; Rønnow, H. M.; Conder, K.

    2010-12-01

    High quality centimeter size single crystals of Bi(Cu 1- xZn x) 2PO 6 ( x=0%, 1%, 5%) have been successfully grown by the Travelling Solvent Floating Zone (TSFZ) technique. The crystals were grown with a rate of 1 mm/h in a gas mixture of 20% O 2 in Ar. Characterization of the single crystal samples by means of optical microscopy, X-ray powder diffraction, X-ray Laue diffraction, neutron diffraction and magnetization measurement are reported. The magnetic susceptibility χspin(T), measured from 2 to 300 K, passes a broad maximum around 60 K, followed by an exponential decrease towards lower T, and confirm the formation of a spin singlet ground state at low temperature. At low-temperature a paramagnetic Curie-like upturn quantitatively reflect the increasing Zn-doping level.

  15. Electrochemical studies of CNT/Si–SnSb nanoparticles for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Nithyadharseni, P. [Department of Physics, Bannari Amman Institute of Technology, Sathyamangalam 638402 (India); Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore); Reddy, M.V., E-mail: phymvvr@nus.edu.sg [Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore); Nalini, B., E-mail: lalin99@rediffmail.com [Department of Physics, Avinashilingam University for Women, Coimbatore 641043 (India); Ravindran, T.R. [Centre for Research in Nanotechnology, Karunya University, Coimbatore 641114 (India); Pillai, B.C.; Kalpana, M. [Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Chowdari, B.V.R. [Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore)

    2015-10-15

    Highlights: • Si added SnSb and CNT exhibits very low particle size of below 30 nm • A strong PL quenching due to the addition of Si to SnSb. • Electrochemical studies show CNT added SnSb shows good capacity retention. - Abstract: Nano-structured SnSb, SnSb–CNT, Si–SnSb and Si–SnSb–CNT alloys were synthesized from metal chlorides of Sn, Sb and Si via reductive co-precipitation technique using NaBH{sub 4} as reducing agent. The as prepared compounds were characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), Raman, Fourier transform infra-red (FTIR) and photoluminescence (PL) spectroscopy. The electrochemical performances of the compounds were characterized by galvanostatic cycling (GC) and cyclic voltammetry (CV). The Si–SnSb–CNT compound shows a high reversible capacity of 1200 mAh g{sup −1}. However, the rapid capacity fading was observed during cycling. In contrast, SnSb–CNT compound showed a high reversible capacity of 568 mAh g{sup −1} at 30th cycles with good cycling stability. The improved reversible capacity and cyclic performance of the SnSb–CNT compound could be attributed to the nanosacle dimension of SnSb particles and the structural advantage of CNTs.

  16. Optoelectronic Structure and Related Transport Properties of Ag2Sb2O6 and Cd2Sb2O7

    Science.gov (United States)

    Irfan, Muhammad; Hussain, Safdar; Khan, Saleem Ayaz; Goumri-Said, Souraya; Azam, Sikander

    2018-02-01

    Using the full-potential linearized augmented-plane wave method, the electronic structure and thermoelectric properties of Ag2Sb2O6 and Cd2Sb2O7 compounds have been explored. The modified Becke-Johnson potential was applied to treat the exchange-correlation energy term. The electronic band structures reveal that the valence-band maximum and conduction-band minimum occur at Γ point, indicating that Ag2Sb2O6 and Cd2Sb2O7 are direct energy bandgap semiconductors. Strong hybridization appeared between Ag (Cd)- s/ p and O- s/ p states. The optical properties, i.e., complex dielectric function, reflectivity, refractive index, and energy loss function, reveal high reflectivity in the ultraviolet energy range, indicating usefulness of these materials in shields from high-energy radiation. Combining transport theory and the outputs from the full-potential linearized augmented-plane wave calculations, the thermoelectric properties were analyzed as functions of temperature. Due to their high thermopower and narrow bandgap, Ag2Sb2O6 and Cd2Sb2O7 are suitable materials for application in optoelectronic and thermoelectric devices.

  17. S123b -NQR study of unconventional superconductivity in the filled skutterudite heavy-fermion compound PrOs4Sb12 under high pressure up to 3.82 GPa

    Science.gov (United States)

    Kawasaki, S.; Katayama, K.; Sugawara, H.; Kikuchi, D.; Sato, H.; Zheng, Guo-Qing

    2008-08-01

    We report S123b nuclear-quadrupole-resonance (NQR) measurements of the filled skutterudite heavy-fermion superconductor PrOs4Sb12 under high pressure. The temperature dependence of NQR frequency and the spin-lattice relaxation rate 1/T1 indicate that the crystal-electric-field splitting ΔCEF between the ground-state Γ1 singlet and the first-excited-state Γ4(2) triplet decreases with increasing pressure. ac-susceptibility measurements indicate that the superconducting transition temperature (Tc) also decreases with increasing pressure. However, above Ptilde 2GPa , both ΔCEF and Tc do not depend on external pressure up to P=3.82GPa . These pressure dependences of ΔCEF and Tc suggest an intimate relationship between quadrupole excitations associated with the Γ4(2) level and unconventional superconductivity in PrOs4Sb12 . In the superconducting state, 1/T1 below Tc=1.55 and 1.57 K at P=1.91 and 2.63 GPa shows a power-law temperature variations and is proportional to T5 at temperatures considerably below Tc . These data can be well fitted by the gap model Δ(θ)=Δ0sinθ , with Δ0=3.08kBTc and 3.04kBTc for P=1.91 and 2.63 GPa, respectively. The results indicate that there exist point nodes in the gap function.

  18. The highest bond order between heavier main-group elements in an isolated compound? Energetics and vibrational spectroscopy of S2I4(MF6)2 (M = As, Sb).

    Science.gov (United States)

    Brownridge, Scott; Cameron, T Stanley; Du, Hongbin; Knapp, Carsten; Köppe, Ralf; Passmore, Jack; Rautiainen, J Mikko; Schnöckel, Hansgeorg

    2005-03-21

    The vibrational spectra of S2I4(MF6)2(s) (M = As, Sb), a normal coordinate analysis of S2I4(2+), and a redetermination of the X-ray structure of S2I4(AsF6)2 at low temperature show that the S-S bond in S2I4(2+) has an experimentally based bond order of 2.2-2.4, not distinguishably different from bond orders, based on calculations, of the Si-Si bonds in the proposed triply bonded disilyne of the isolated [(Me3Si)2 CH]2 (iPr)SiSiSiSi(iPr)[CH(SiMe3)2]2 and the hypothetical trans-RSiSiR (R = H, Me, Ph). Therefore, both S2I4(2+) and [(Me3Si)2 CH]2 (iPr)SiSiSiSi(iPr)[CH(SiMe3)2]2 have the highest bond orders between heavier main-group elements in an isolated compound, given a lack of the general acceptance of a bond order > 2 for the Ga-Ga bond in Na2[{Ga(C6H3Trip2-2,6)}2] (Trip = C6H2Pr(i)3-2,4,6) and the fact that the reported bond orders for the heavier group 14 alkyne analogues of formula REER [E = Ge, Sn, or Pb; R = bulky organic group] are ca. 2 or less. The redetermination of the X-ray structure gave a higher accuracy for the short S-S [1.842(4) A, Pauling bond order (BO) = 2.4] and I-I [2.6026(9) A, BO = 1.3] bonds and allowed the correct modeling of the AsF6- anions, the determination of the cation-anion contacts, and thus an empirical estimate of the positive charge on the sulfur and iodine atoms. FT-Raman and IR spectra of both salts, obtained for the first time, were assigned with the aid of density functional theory calculations and gave a stretching frequency of 734 cm(-1) for the S-S bond and 227 cm(-1) for the I-I bond, implying bond orders of 2.2 and 1.3, respectively. A normal-coordinate analysis showed that no mixing occurs and yielded force constants for the S-S (5.08 mdyn/A) and I-I bonds (1.95 mdyn/A), with corresponding bond orders of 2.2 for the S-S bond and 1.3 for the I-I bond, showing that S2I4(2+) maximizes pi bond formation. The stability of S2I4(2+) in the gas phase, in SO2 and HSO3F solutions, and in the solid state as its AsF6- salts was

  19. Polar intermetallic compounds of the silicon and arsenic family elements and their ternary hydrides and fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Leon-Escamilla, E.A.

    1996-10-17

    An investigation has been made on the effects of hydrogen and fluoride in the solid state chemistry of alkaline-earth and divalent rare-earth metal pnictide (Pn) and tetrelide (Tt) phases A{sub 5}(Pn,Tt,){sub 3}Z{sub x}, where A = Ca, Sr, Ba, Sm, Eu, Yb; Pn = As, Sb, Bi; Tt = Si, Ge, Sn, Pb and Z = H, F. Several trivalent rare-earth-metal pnictides, RE{sub 5}Pn{sub 3} (RE = Y, La, Gd, Tb, Dy, Ho, Er, Tm) and alkaline-earth-metal trielides, A{sub 5}Tr{sub 3}Z{sub x} (Tr = Ga, In, Tl) have been included in an effort to complete observed structural trends. Two main experimental techniques were followed throughout this work, (a) reactions in absence of hydrogen or under continuous high vacuum, and (b) reactions with binary metal hydrides, AH{sub x}, in closed containers. The results demonstrate that all the phases reported with the {beta}-Yb{sub 5}Sb{sub 3}-type structure in the A{sub 5}Pn{sub 3} systems are hydrogen-stabilized compounds. Reactions in absence of hydrogen lead to compounds with the Mn{sub 5}Si{sub 3}-type structure. The structure type {beta}-Yb{sub 5}Sb{sub 3} (= Ca{sub 5}SB{sub 3}F) was found to be characteristic of ternary systems and inaccurately associated with phases that form in the Y{sub 5}Bi{sub 3}-type. A new series of isomorphous Zintl compounds with the Ca{sub 16}Sb{sub 11}-type structure were prepared and studied as well. All the alkaline-earth-metal tetrelides, A{sub 5}Tt{sub 3}, that crystallize in the Cr{sub 5}B{sub 3}-type structure can be interstitially derivatized by hydrogen or fluoride. Binary and ternary compounds were characterized by Guinier powder patterns, single crystal X-ray and powder neutron diffraction techniques. In an effort to establish property-structure relationships, electrical resistivity and magnetic measurements were performed on selected systems, and the results were explained in terms of the Zintl concepts, aided by extended Hueckel band calculations.

  20. The Effect of Sb Addition on Sn-Based Alloys for High-Temperature Lead-Free Solders: an Investigation of the Ag-Sb-Sn System

    Science.gov (United States)

    Li, D.; Delsante, S.; Watson, A.; Borzone, G.

    2012-01-01

    Today there is renewed interest in alloys belonging to the Sb-Sn-X (X = Cu, Ag, Bi) ternary systems and their phase equilibria, phase transformations, and thermodynamic properties because of their possible use as high-temperature lead-free solders in the electronics industry. The integral mixing enthalpy of Ag-Sb-Sn liquid alloys has been measured along five different sections (Ag0.25Sn0.75, Ag0.50Sn0.50, Sb0.30Sn0.70, Sb0.50Sn0.50, and Sb0.70Sn0.30) at 530°C, 600°C, and 630°C, using a high-temperature Calvet calorimeter by dropping pure elements (Ag or Sb) in the binary alloy liquid bath. The ternary extrapolation models of Muggianu and Toop were used to calculate the integral enthalpy of mixing and to compare measured and extrapolated values. Selected ternary alloys have been prepared for thermal investigation by using a differential scanning calorimeter at different heating/cooling rates in order to clarify the temperature of the invariant reactions and the crystallization path.

  1. Interfacial Reaction and Mechanical Properties of Sn-Bi Solder joints.

    Science.gov (United States)

    Wang, Fengjiang; Huang, Ying; Zhang, Zhijie; Yan, Chao

    2017-08-09

    Sn-Bi solder with different Bi content can realize a low-to-medium-to-high soldering process. To obtain the effect of Bi content in Sn-Bi solder on the microstructure of solder, interfacial behaviors in solder joints with Cu and the joints strength, five Sn-Bi solders including Sn-5Bi and Sn-15Bi solid solution, Sn-30Bi and Sn-45Bi hypoeutectic and Sn-58Bi eutectic were selected in this work. The microstructure, interfacial reaction under soldering and subsequent aging and the shear properties of Sn-Bi solder joints were studied. Bi content in Sn-Bi solder had an obvious effect on the microstructure and the distribution of Bi phases. Solid solution Sn-Bi solder was composed of the β-Sn phases embedded with fine Bi particles, while hypoeutectic Sn-Bi solder was composed of the primary β-Sn phases and Sn-Bi eutectic structure from networked Sn and Bi phases, and eutectic Sn-Bi solder was mainly composed of a eutectic structure from short striped Sn and Bi phases. During soldering with Cu, the increase on Bi content in Sn-Bi solder slightly increased the interfacial Cu₆Sn₅ intermetallic compound (IMC)thickness, gradually flattened the IMC morphology, and promoted the accumulation of more Bi atoms to interfacial Cu₆Sn₅ IMC. During the subsequent aging, the growth rate of the IMC layer at the interface of Sn-Bi solder/Cu rapidly increased from solid solution Sn-Bi solder to hypoeutectic Sn-Bi solder, and then slightly decreased for Sn-58Bi solder joints. The accumulation of Bi atoms at the interface promoted the rapid growth of interfacial Cu₆Sn₅ IMC layer in hypoeutectic or eutectic Sn-Bi solder through blocking the formation of Cu₆Sn₅ in solder matrix and the transition from Cu₆Sn₅ to Cu₃Sn. Ball shear tests on Sn-Bi as-soldered joints showed that the increase of Bi content in Sn-Bi deteriorated the shear strength of solder joints. The addition of Bi into Sn solder was also inclined to produce brittle morphology with interfacial fracture, which

  2. Realization of single and double axial InSb-GaSb heterostructure nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ghalamestani, Sepideh Gorji [Solid State Physics, Lund University, Lund (Sweden); Ek, Martin [Center for Analysis and Synthesis, Lund University, Lund (Sweden); Dick, Kimberly A. [Solid State Physics, Lund University, Lund (Sweden); Center for Analysis and Synthesis, Lund University, Lund (Sweden)

    2014-03-15

    Heteroepitaxial growth of III-Sb nanowires allows for the formation of various interesting complex structures and enables the combination of their remarkable properties. In this Letter, we investigate the heteroepitaxial growth of Au-seeded InSb and GaSb nanowires using metalorganic vapor phase epitaxy. We demonstrate successful single and double axial InSb-GaSb heterostructures in both directions. The formation properties of the grown nanowires including the compositional change of the particle and the interface sharpness are further discussed. In addition, the decomposition of InSb and GaSb segments and their side facet evolution are explained. XEDS compositional line scans overlaid on STEM HAADF image along the InSb-GaSb-InSb nanowire indicating sharp interface from GaSb to InSb segment and graded interface in the opposite direction. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Synthesis, crystal structure, electronic structure, and photoelectric response properties of KCu2SbS3.

    Science.gov (United States)

    Wang, Ruiqi; Zhang, Xian; He, Jianqiao; Zheng, Chong; Lin, Jianhua; Huang, Fuqiang

    2016-02-28

    Copper thioantimonates have received enormous attention due to their potential for applications in photovoltaic devices. In this work, a new layered compound KCu2SbS3 was synthesized via a reactive flux method using thiourea as a reactive flux. The compound crystallizes in the triclinic space group P1[combining macron]. The structure features two-dimensional [Cu2SbS3](-) layers stacking along the c axis with K(+) ions intercalated between the layers. Each [Cu2SbS3](-) layer is composed of two single graphene-like layers connected via interlayer Cu-S bonds and CuSb contacts. The optical measurements indicate that the compound has a band gap of 1.7 eV. The Hall effect measurement shows that KCu2SbS3 is a p-type semiconductor with a carrier concentration of 7 × 10(16) cm(-3). First-principles calculations reveal that the direct transition occurs between Cu-3d-S-3p orbitals (VBM) to Sb-5p-S-3p orbitals (CBM). The photoelectric response properties of KCu2SbS3 under visible light irradiation were analyzed. The photocurrent is 3.7 μA cm(-2) at 10 V bias, demonstrating its potential for applications in photoelectric devices.

  4. Crystal structures of a pentavalent bismuthate, SrBi2O6 and a lead bismuth oxide (Pb1/3Bi2/3O1.4

    Directory of Open Access Journals (Sweden)

    Nobuhiro Kumada

    2014-06-01

    Full Text Available The crystal structures of a pentavalent bismuthate, SrBi2O6 with the PbSb2O6-type structure and a lead bismuth oxide, (Pb1/3Bi2/3O1.4 with the fluorite-type structure were refined by using neutron diffraction data. The final R-factors were Rwp = 4.49, Rp = 3.46, RI = 4.50 and RF = 1.70% for SrBi2O6 and Rwp = 5.04, Rp = 3.93, RI = 5.47 and RF = 4.26% for (Pb1/3Bi2/3O1.4. SrBi2O6 prepared from NaBiO3·1.4H2O is the first example of the bismuthate with the PbSb2O6-type structure. The fluorite-type lead bismuth oxide, (Pb1/3Bi2/3O1.4 was obtained by heating the PbSb2O6-type lead bismuthate, PbBi2O5.9·H2O which was prepared also from NaBiO3·1.4H2O.

  5. Transformation/dissolution examination of antimony and antimony compounds with speciation of the transformation/dissolution solutions.

    Science.gov (United States)

    Skeaff, James M; Beaudoin, Robert; Wang, Ruiping; Joyce, Barry

    2013-01-01

    Speciation is held to be a key factor in controlling the ecotoxicity of metals in solution. Using the United Nations transformation/dissolution protocol (T/DP) for metals and sparingly soluble metal compounds, we have examined the transformation/dissolution (T/D) characteristics in terms of the concentrations of total dissolved Sb at pH 6 and 8.5 in 1, 10, and 100 mg/L loadings over 7 d as well as the concentrations of Sb(III) and Sb(V) at the 1 mg/L loadings over 28 d, of sodium hexahydroxoantimonate (NaSb(OH)(6)), antimony metal (Sb), antimony trioxide (Sb(2) O(3)), antimony sulfide (Sb(2) S(3)), sodium antimonate (NaSbO(3)), antimony tris(ethylene glycolate) (Sb(2) (C(2) H(4) O(2) )(3)), antimony trichloride (SbCl(3)), antimony triacetate (Sb(CH(3) COO)(3)), and antimony pentoxide (Sb(2) O(5) ). We also measured the concentrations of the dissolved Sb(III) and Sb(V) species at the 1 mg/L loadings. Because of complexing, the trivalent organic Sb compounds exhibited little or no oxidation of Sb(III) to Sb(V). However, oxidation of Sb(III) to Sb(V) was evident for the trivalent inorganic Sb compounds. Conversely, with pentavalent Sb compounds, there was no reduction of Sb(V) to Sb(III). Based on the percentage of Sb in the compound dissolved or metal reacted at 28 d and 1 mg/L loadings, the solubility rankings at pH 6 are NaSb(OH)(6)  > Sb(CH(3) COO)(3)  > Sb metal > Sb(2) (C(2) H(4) O(2))(3)  > Sb(2) S(3)  > Sb(2) O(3)  > NaSbO(3)  ≈ SbCl(3)  > Sb(2) O(5). For pH 8.5 the order is NaSb(OH)(6)  > Sb(CH(3) COO)(3)  > Sb metal > Sb(2) (C(2) H(4) O(2) )(3)  > SbCl(3)  > Sb(2) O(3)  > Sb(2) S(3)  > NaSbO(3)  > Sb(2) O(5) . We provide worked examples of how the T/D data have been used to derive hazard classification proposals for Sb metal and these selected compounds for submission to the European Chemicals Agency under the Registration, Evaluation, Authorization and Restriction of CHemicals (REACH

  6. Thermoelectric Property of Ag-doped ZnSb/Few-Layer-Graphene Composites

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kwang Min; Lee, Eunsil; Ko, Jieun; Kim, Jong-Young [Korea Institute of Ceramic Engineering and Technology, Icheon (Korea, Republic of); Lee, Soonil; Seo, Won-Seon [Korea Institute of Ceramic Engineering and Technology, Jinju (Korea, Republic of); Choi, Soon-Mok [Korea University of Technology and Education, Cheonan (Korea, Republic of); Lee, Kyu Hyoung [Kangwon National University, Chuncheon (Korea, Republic of); Kim, Seung Joo [Ajou University, Suwon (Korea, Republic of)

    2016-05-15

    We have successfully synthesized the composites of Ag-doped zinc antimonide (Ag-ZnSb) and few-layer-graphene (FLG) by high-energy-mechanical milling and spark plasma sintering using Ag-ZnSb ingot and FLG as raw materials. The FLG/Ag-ZnSb shows 22%-reduced lattice thermal conductivity by increased phonon boundary scattering due to embedded FLG. The electrical conductivity of the composites was decreased due to reduced carrier concentration, while the Seebeck coefficient of the composites was increased by electron donating effect of FLG. The maximum figure of merit, ZT, of 0.86 was observed at 630 K. The peak ZT temperature in the FLG/Ag-ZnSb cases (⁓630 K) were higher than the pristine Ag-ZnSb compound (⁓580 K) resulting in advantages for the higher temperature power generation.

  7. Magnetic and dielectric properties in the langasite-type compounds: A3BFe3D2O14 (A=Ba,Sr,Ca;B=Ta,Nb,Sb;D=Ge,Si)

    Science.gov (United States)

    Marty, Karol; Bordet, Pierre; Simonet, Virginie; Loire, Mickael; Ballou, Rafik; Darie, Céline; Kljun, Jakob; Bonville, Pierre; Isnard, Olivier; Lejay, Pascal; Zawilski, Bartosz; Simon, Charles

    2010-02-01

    The Fe-based langasites are the only reported compounds presenting a magnetic ordering in this rich family, besides being well known for piezoelectric properties and optical activity. The structural, magnetic, and dielectric properties of the Fe-langasite compounds, with various substitution of nonmagnetic cations, have been studied with x-ray and neutron-diffraction, magnetostatic measurements, Mössbauer spectroscopy, and dielectric measurements. The title compounds (trigonal space group P321 ) display a helical magnetic order with signatures of frustration below TN≈24-35K , where an anomaly of the dielectric permittivity is observed. The influence of the cationic substitutions and the nature of the magnetoelectric coupling are hereafter addressed.

  8. Structural study of modified Bi{sub 4}V{sub 2}O{sub 10+{delta}} phases ({delta} = 0, 0.5, 1): Influence of antimony contribution

    Energy Technology Data Exchange (ETDEWEB)

    Sorokina, S.; Enjalbert, R.; Baules, P.; Galy, J. [CNRS, Toulouse (France). Centre d`Elaboration de Materiaux et d`Etudes Structurales; Castro, A. [CSIC, Cantoblanco, Madrid (Spain). Inst. de Ciencia de Materiales

    1999-05-01

    Three solid solutions of general composition Bi{sub 4{minus}x}Sb{sub x}V{sub 2}O{sub 10}, Bi{sub 4}V{sub 2{minus}y}{sup 4+}V{sub y}{sup 5+}O{sub 10+y/2}, and Bi{sub 4}V{sub 2{minus}z}Sb{sub z}O{sub 11} have been investigated in the fivefold Bi{sub 2}O{sub 3}-V{sub 2}O{sub 5}-V{sub 2}O{sub 4}-Sb{sub 2}O{sub 3}-Sb{sub 2}O{sub 5} system. These oxides have been characterized by X-ray diffraction and electron microscopy techniques. Single phases have been isolated for values ranging from 0 to x, z = 0.8 and y = 2. Single crystals of Bi{sub 3.2}Sb{sub 0.8}V{sub 2}O{sub 10}, Bi{sub 4}V{sub 2}O{sub 10.5}, and Bi{sub 4}V{sub 1.2}Sb{sub 0.8}O{sub 11} have been grown and their structures determined by X-ray diffraction methods. The three oxides crystallize in the orthorhombic system, space groups F222, Amam, and Fmmm, respectively. Their structures keep the classical two-dimensional array of Aurivillius-like oxides with (Bi, Sb)-O layers interleaved with (V, Sb)-O sheets. It has been found that Sb{sup 3+} is introduced into the bismuth layer, due to its similar sterical behavior, by the presence of a 5s{sup 2} lone pair associated with Sb{sup 3+} and 6s{sup 2} associated with Bi{sup 3+}, whereas Sb{sup 5+} substitutes for the V{sup 5+} cation. All of the substitutions carried out mainly act on the vanadium layer, which can accommodate different coordination polyhedra for cations: tetrahedra for V{sup 5+}, square pyramids and distorted trigonal bipyramids or octahedra for V{sup 4+} and V{sup 5+}, and octahedra for Sb{sup 5+}. This fact can be related to the electrical properties, such as high ionic conduction and ferroelectricity, shown by these types of materials.

  9. Solution route synthesis of InSb, Cu 6Sn 5 and Cu 2Sb electrodes for lithium batteries

    Science.gov (United States)

    Sarakonsri, T.; Johnson, C. S.; Hackney, S. A.; Thackeray, M. M.

    A solution method was used to prepare InSb, Cu 6Sn 5 and Cu 2Sb intermetallic compounds that are of interest as negative electrode materials for lithium batteries. The compounds were synthesized by the reduction of dissolved transition metal- and metalloid salts with fine Zn powder. Heterogeneous redox reactions at the surface of the Zn particles resulted in fern-like dendritic structures with high surface areas. Powder X-ray diffraction and lattice imaging by transmission electron microscopy showed that the intermetallic products were highly crystalline with preferred crystallographic orientations. Mild heat-treatment of the products under argon improved their phase purity. Electrodes prepared by this method exhibited a large irreversible capacity loss on the first charge/discharge cycle. Cu 2Sb electrodes showed the greatest cycling stability; after the initial cycle, they delivered more than 230 mAh g -1 when cycled between 1.2 and 0.0 V versus metallic lithium, consistent with previously reported data for ball-milled Cu 2Sb electrodes.

  10. Alternative anode materials for lithium-ion batteries: a study of Ag 3Sb

    Science.gov (United States)

    Vaughey, J. T.; Fransson, L.; Swinger, H. A.; Edström, K.; Thackeray, M. M.

    Silver antimonide, Ag 3Sb, in which silver and antimony are both electrochemically active toward lithium, has been studied as an anode for lithium-ion batteries. The rate of capacity fade on cycling was monitored as a function of the voltage window, which has provided further information about the causes of capacity fade in intermetallic electrode systems. From the voltage profiles, and by comparison with the behavior of SnSb, InSb and Cu 2Sb electrodes, the electrochemical reaction of Li/Ag 3Sb cells was determined to take place in several discrete stages: first, by a displacement reaction in which lithium replaces Ag in the Ag 3Sb structure in a two-step process between 0.9 and 0.7 V to form Li 3Sb via Li 2AgSb; and second, by reaction of lithium with the extruded silver between 0.2 and 0.0 V to form Li xAg compounds (1≤ x≤4). The rate of capacity fade that occurs when cells are cycled between 1.2 and 0.0 V was significantly reduced by limiting the reaction to either: (1) the low voltage region (0.7-0.0 V), which provided a stable capacity of ˜300 mAh/g; or (2) to a wider operating window (1.2-0.1 V, 250 mAh/g), in which the formation of Li xAg phases was suppressed.

  11. Ionothermal Synthesis, Structure, and Bonding of the Catena -Heteropolycation 1 ∞ [Sb 2 Se 2 ] +

    KAUST Repository

    Groh, Matthias F.

    2015-01-26

    The reaction of antimony and selenium in the Lewis-acidic ionic liquid 1-butyl-3-methyl-imidazolium tetrachloridoaluminate, [BMIm]Cl•4.7AlCl3, yielded dark-red crystals of [Sb2Se2]AlCl4. The formation starts above 160 ° C; at about 190 ° C, irreversible decomposition takes place. The compound crystallizes in the triclinic space group P 1¯ with a = 919.39(2) pm, b = 1137.92(3) pm, c = 1152.30(3) pm, α = 68.047(1)° , β = 78.115(1)° , γ = 72.530(1)° , and Z = 4. The structure is similar to that of [Sb2Te2]AlCl4 but has only half the number of crystallographically independent atoms. Polycationic chains 1∞ [Sb2Se2]+ form a pseudo-hexagonal arrangement along [011¯] ], which is interlaced by tetrahedral AlCl4 - groups. The catena-heteropolycation 1∞ [Sb2Se2]+ is a sequence of three different four-membered [Sb2Se2 ] rings. The chemical bonding scheme, established from the topological analysis of the real-space bonding indicator ELI-D, includes significantly polar covalent bonding in four-member rings withinthepolycation.Theringsareconnectedintoaninfinitechainbyhomonuclear non-polar Sb-Sb bonds and highly polar Sb-Se bonds. Half of the selenium atoms are three-bonded.

  12. Biocompatibility of GaSb thin films grown by RF magnetron sputtering

    Science.gov (United States)

    Nishimoto, Naoki; Fujihara, Junko; Yoshino, Katsumi

    2017-07-01

    GaSb may be suitable for biological applications, such as cellular sensors and bio-medical instrumentation because of its low toxicity compared with As (III) compounds and its band gap energy. Therefore, the biocompatibility and the film properties under physiological conditions were investigated for GaSb thin films with or without a surface coating. GaSb thin films were grown on quartz substrates by RF magnetron sputtering, and then coated with (3-mercaptopropyl) trimethoxysilane (MPT). The electrical properties, surface morphology, and crystal structure of the GaSb thin film were unaffected by the MPT coating. The cell viability assay suggested that MPT-coated GaSb thin films are biocompatible. Bare GaSb was particularly unstable in pH9 buffer. Ga elution was prevented by the MPT coating, although the Ga concentration in the pH 9 buffer was higher than that in the other solutions. The surface morphology and crystal structure were not changed by exposure to the solutions, except for the pH 9 buffer, and the thin film properties of MPT-coated GaSb exposed to distilled water and H2O2 in saline were maintained. These results indicate that MPT-coated GaSb thin films are biocompatible and could be used for temporary biomedical devices.

  13. Bonding in ZnSb

    DEFF Research Database (Denmark)

    Bjerg, Lasse; Madsen, Georg K. H.; Iversen, Bo Brummerstedt

    Thermoelectric materials are capable of converting waste heat into usable electric energy. The conversion efficiency depends critically on the electronic band structure. Theoretical calculations predict the semiconducting ZnSb to have a promising efficiency if it is n-doped. The details of the lo......Thermoelectric materials are capable of converting waste heat into usable electric energy. The conversion efficiency depends critically on the electronic band structure. Theoretical calculations predict the semiconducting ZnSb to have a promising efficiency if it is n-doped. The details...

  14. The crystal structure of Cu9.1(1)TeSb3, a stuffed derivative of Cr3Si

    DEFF Research Database (Denmark)

    Søtofte, Inger; Makovicky, E.; Karup-Møller, Sven

    1998-01-01

    The intermetallic compound Cu9.1(1)TeSb3 prepared at 973 K is an ordered member of the solid solution Cu64Te31Sb5-Cu70Te8Sb22 which also exists, for more limited composition ranges, between 673 K and 1173 K. It is a stuffed derivative of the structure type A15 (Cr3Si). Te is surrounded by twelve ....../4-occupied Cu-positions in the vertices of a cubically-deformed icosahedron (Cu-Te = 2.614 Å) which itself is nested in an Sb-icosahedron (Cu-Sb = 2.777 Å (x2) and 2.603 Å). The Sb array corresponds to the Cr array in Cr3Si....

  15. High pressure synthesis of BiS2

    DEFF Research Database (Denmark)

    Søndergaard-Pedersen, Simone; Nielsen, Morten Bormann; Bremholm, Martin

    crystal structures and electrical properties.1,2 Up until now, the most sulfur rich phase in the Bi-S phase diagram was Bi2S3.3 For BiS2 the Bi atoms have anisotropic charge distribution and more complex structures are expected when comparing the layered structures of transition metal dichalcogenides....... The possibilities of using high pressure synthesis to discover new phases in the Bi-S binary system were investigated as early as the 1960’s.4 The research led to discovery of a compound with BiS2 stoichiometry, but no structure solution of BiS2 was reported. A reason behind making this new phase is to study...

  16. Time reversal symmetry breaking in superconducting(Pr,La)Os{sub 4}Sb{sub 12} and Pr(Os,Ru){sub 4}Sb{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Shu, L. [Department of Physics, University of California, Riverside, CA 92521 (United States)]. E-mail: lei.shu@email.ucr.edu; Higemoto, W. [Japan Atomic Energy Agency, Tokai-Mura, Ibaraki 319-1195 (Japan); Aoki, Y. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Frederick, N.A. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); Yuhasz, W.M. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Heffner, R.H. [Japan Atomic Energy Agency, Tokai-Mura, Ibaraki 319-1195 (Japan); Ohishi, K. [Japan Atomic Energy Agency, Tokai-Mura, Ibaraki 319-1195 (Japan); Ishida, K. [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Kadono, R. [Meson Science Laboratory, KEK, Tsukuba, Ibaraki 305-0801 (Japan); Koda, A. [Meson Science Laboratory, KEK, Tsukuba, Ibaraki 305-0801 (Japan); Kikuchi, D. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Sato, H. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Sugawara, H. [Faculty of the Integrated Arts and Sciences, University of Tokushima, Minami-jousanjima-machi 1-1, Tokushima 770-8502 (Japan); Ito, T.U. [Japan Atomic Energy Agency, Tokai-Mura, Ibaraki 319-1195 (Japan); Sanada, S. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Tunashima, Y. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Yonezawa, Y. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Maple, M.B. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); MacLaughlin, D.E. [Department of Physics, University of California, Riverside, CA 92521 (United States)

    2007-03-15

    Zero-field muon spin relaxation ({mu}SR) experiments have been carried out in the Pr(Os{sub 1-x}Ru{sub x}){sub 4}Sb{sub 12} and Pr{sub 1-y}La{sub y}Os{sub 4}Sb{sub 12} alloy systems to investigate the time-reversal symmetry (TRS) breaking found in an earlier ZF-{mu}SR study of the end compound PrOs{sub 4}Sb{sub 12}. Our results suggest that Ru doping is considerably more efficient than La doping in suppressing TRS-breaking superconducting pairing in PrOs{sub 4}Sb{sub 12}.

  17. Role of the interlayer coupling for the thermoelectric properties of CuSbS2 and CuSbSe2

    Science.gov (United States)

    Alsaleh, Najebah; Singh, Nirpendra; Schwingenschlogl, Udo

    The electronic and transport properties of bulk and monolayer CuSbS2 and CuSbSe2 are determined using density functional theory and semi-classical Boltzmann transport theory, in order to investigate the role of the interlayer coupling for the thermoelectric properties. The calculated band gaps of the bulk compounds are in agreement with experiments and significantly higher than those of the monolayers, which thus show lower Seebeck coefficients. Since also the electrical conductivity is lower, the monolayers are characterised by lower power factors. Therefore, the interlayer coupling is found to be essential for the excellent thermoelectric response of CuSbS2 and CuSbSe2 even though it is of weak van der Waals type. The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST).

  18. Structural, elastic and magnetic properties of Mn and Sb doped chromium nitride – An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Ikram Un Nabi Lone; Sheik Sirajuddeen M Mohamed, E-mail: msheiksiraj@bsauniv.ac.in; Shameem Banu, I.B.; Sathik Basha, S.

    2017-05-01

    Structural, magnetic and elastic properties of Mn and Sb doped CrN were investigated by the electronic band structure calculations using Full Potential Linear Augmented Plane Wave (FP-LAPW) method. The host compound CrN was doped with Mn and Sb separately, in the doping concentration of 12.5% to replace Cr atoms. The introduction of Mn and Sb atoms replacing the Cr atoms does not change the structural stability of the compound. The changes in magnetic and elastic properties were investigated and compared in GGA and GGA+U methods. The doped CrN undergoes a relative increase in the magnetic order with the substitution of Mn and Sb atoms. In GGA method, the magnetic moments are found to be greater in Mn doped CrN than that found in Sb doped Cr{sub 0.875}NSb{sub 0.125}. When doped with Sb, the elastic moduli such as Young’s modulus, bulk modulus and rigidity modulus show a relative increase in comparison with that in Mn doped CrN. Using Hubbard model in GGA+U method, both the magnetic and elastic properties increase in Mn and Sb doped compounds. - Highlights: • Mn and Sb doped Chromium Nitride. • Structural properties. • Magnetic properties. • Elastic properties.

  19. Structural and magnetic properties of GaSb:MnSb granular layers

    Energy Technology Data Exchange (ETDEWEB)

    Dynowska, E., E-mail: dynow@ifpan.edu.pl [Institute of Physics Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Bak-Misiuk, J.; Romanowski, P.; Domagala, J.Z. [Institute of Physics Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Sadowski, J. [Institute of Physics Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); MAX-Lab, Lund University P.O. Box. 118, S-22100 Lund (Sweden); Wojciechowski, T.; Kret, S.; Kurowska, B. [Institute of Physics Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Kwiatkowski, A. [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Hoza 69, PL-00681 Warsaw (Poland); Caliebe, W. [Hasylab at DESY, Notkestr. 85, D-22607 Hamburg (Germany)

    2011-10-15

    The results of structural and magnetic characterization of GaMnSb layers grown on GaSb(0 0 1) and GaAs(1 1 1) substrates are presented. The presence of hexagonal, highly oriented MnSb inclusions embedded in GaSb matrix has been demonstrated. The lattice parameters of these inclusions were the same as those for bulk MnSb for the layers grown on GaSb(1 0 0) substrate while for the layers grown on GaAs(1 1 1) the MnSb inclusions were strained. The influence of a presence of MnSb clusters on the lattice parameter of GaSb matrix has been demonstrated. It was confirmed that in all cases the MnSb clusters exhibit a ferromagnetic behavior at room temperature.

  20. LPEE Growth and Characterization of InxGa(1-x)ASySb(1-y) Lattice Matched to GaSb and InAs for Photodetectors

    Science.gov (United States)

    1994-06-01

    S. Nishiyama, S. Isozumi and K.Nakajima, Appl.Phys.Lett. 56, 239 (1990). 25. S.J.Eglash and H.K. Choi , Gallium Arsenide and Related Compounds. 1991...51 (1986). 3*S. J, Eglash and H. K. Choi , in Gallium Arsenide and Related Compounds, 1991, edited by G. B. Stringfellow (IOP, London, 1992), p...GalnAsSb layers on a (100) GaSb substrate. Considering the fact that this is a quater- nary alloy system and hence even a small statistical inho

  1. Controllable topological transformation from BiOCl hierarchical microspheres to Bi{sub 2}WO{sub 6} superstructures in the Bi–W–Cl–O system

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jiao [National Engineering Research Center for Manufacturing Equipment Digitization, Department of Mechanical Science and Engineering, Huazhong University of Science and Technology (HUST), No. 1037, Luoyu Road, Wuhan 430074 (China); State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Shi, Songxin, E-mail: shisx@hust.edu.cn [National Engineering Research Center for Manufacturing Equipment Digitization, Department of Mechanical Science and Engineering, Huazhong University of Science and Technology (HUST), No. 1037, Luoyu Road, Wuhan 430074 (China); Tang, Tengteng [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Tian, Shouqin [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Yang, Wenjuan [State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Zeng, Dawen [Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China)

    2015-09-15

    Graphical abstract: The three-dimensional (3D) Bi{sub 2}WO{sub 6} superstructures assembled by nanosheets were directly transformed topologically from BiOCl hierarchical microspheres via a facile one-pot solvothermal method. Furthermore, the crystal growth of Bi{sub 2}WO{sub 6} superstructure was confirmed to occur at the exposed plane (0 0 1) of BiOCl nanosheets with WO{sub 6}{sup 6−} units replacing the interlaminar Cl atoms. Their similar layered structures favored the controllable transformation of BiOCl to Bi{sub 2}WO{sub 6} through the substitution process. And this topological transformation may provide a new prospective to the synthesis of other 3D compounds. - Highlights: • Bi{sub 2}WO{sub 6} superstructures were prepared by topological transformation of BiOCl assembly. • Transformation process experienced three stages of BiOCl, BiOCl/Bi{sub 2}WO{sub 6} and Bi{sub 2}WO{sub 6}. • Bi{sub 2}WO{sub 6} superstructures grew at the exposed (0 0 1) facets of BiOCl nanosheets. • The growth mechanism was revealed from thermodynamic and kinetic dynamic aspects. - Abstract: In this work, three-dimensional (3D) Bi{sub 2}WO{sub 6} superstructures assembled by nanosheets were prepared using the topological transformation of BiOCl hierarchical microspheres via a facile one-pot solvothermal method. Interestingly, it was found that the transformation process experienced three stages including BiOCl, BiOCl/Bi{sub 2}WO{sub 6} composites and Bi{sub 2}WO{sub 6} with increasing solvothermal time at 150 °C, which was confirmed by X-Ray Diffraction (XRD), Raman spectrometer and Transmission Electron Microscopy (TEM) results. Importantly, the crystal growth of Bi{sub 2}WO{sub 6} superstructures occurred at the exposed (0 0 1) facets of BiOCl nanosheets with WO{sub 6}{sup 6−} units replacing the interlaminar Cl atoms. Also, the growth mechanism was revealed and discussed in the thermodynamic and kinetic dynamic aspects. Compared with BiOCl superstructures, the BiOCl/Bi

  2. Behavior of GaSb (100) and InSb (100) surfaces in the presence of H{sub 2}O{sub 2} in acidic and basic cleaning solutions

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Dongwan; Na, Jihoon; Lee, Seunghyo; Lim, Sangwoo, E-mail: swlim@yonsei.ac.kr

    2017-03-31

    Highlights: • Surface behavior of GaSb and InSb was investigated in acidic and basic solutions. • H{sub 2}O{sub 2} plays a key role in the surface oxidation of GaSb and InSb in acidic hydrochloric acid/hydrogen peroxide mixture (HPM) solution. • GaSb and InSb surfaces were hardly oxidized in basic ammonium hydroxide/hydrogen peroxide mixture (APM) solution in the presence of H{sub 2}O{sub 2}. • The effect of dilution of APM solution on the oxidation of the InSb surface was minimal. • Surface characteristics of GaSb and InSb in HPM and APM solutions are mainly determined by the behaviors of the group III elements rather than the group V element. - Abstract: Gallium antimonide (GaSb) and indium antimonide (InSb) have attracted strong attention as new channel materials for transistors due to their excellent electrical properties and lattice matches with various group III–V compound semiconductors. In this study, the surface behavior of GaSb (100) and InSb (100) was investigated and compared in hydrochloric acid/hydrogen peroxide mixture (HPM) and ammonium hydroxide/hydrogen peroxide mixture (APM) solutions. In the acidic HPM solution, surface oxidation was greater and the etching rates of the GaSb and InSb surfaces increased when the solution is concentrated, which indicates that H{sub 2}O{sub 2} plays a key role in the surface oxidation of GaSb and InSb in acidic HPM solution. However, the GaSb and InSb surfaces were hardly oxidized in basic APM solution in the presence of H{sub 2}O{sub 2} because gallium and indium are in the thermodynamically stable forms of H{sub 2}GaO{sub 3}{sup −} and InO{sub 2}{sup −}, respectively. When the APM solution was diluted, however, the Ga on the GaSb surface was oxidized by H{sub 2}O, increasing the etching rate. However, the effect of dilution of the APM solution on the oxidation of the InSb surface was minimal; thus, the InSb surface was less oxidized than the GaSb surface and the change in the etching rate of InSb

  3. Surface Collective Modes in the Topological Insulators Bi2Se3 and Bi0.5Sb1.5Te3-xSex

    Energy Technology Data Exchange (ETDEWEB)

    Kogar, A.; Vig, S.; Thaler, A.; Wong, M. H.; Xiao, Y.; Reig-i-Plessis, D.; Cho, G. Y.; Valla, T.; Pan, Z.; Schneeloch, J.; Zhong, R.; Gu, G. D.; Hughes, T. L.; MacDougall, G. J.; Chiang, T. -C.; Abbamonte, P.

    2015-12-01

    We used low-energy, momentum-resolved inelastic electron scattering to study surface collective modes of the three-dimensional topological insulators Bi2Se3 and Bi0.5Sb1.5Te3-xSex . Our goal was to identify the “spin plasmon” predicted by Raghu and co-workers [Phys. Rev. Lett. 104, 116401 (2010)]. Instead, we found that the primary collective mode is a surface plasmon arising from the bulk, free carriers in these materials. This excitation dominates the spectral weight in the bosonic function of the surface χ '' ( q , ω ) at THz energy scales, and is the most likely origin of a quasiparticle dispersion kink observed in previous photoemission experiments. Our study suggests that the spin plasmon may mix with this other surface mode, calling for a more nuanced understanding of optical experiments in which the spin plasmon is reported to play a role.

  4. Low-energy spin fluctuations in filled skutterudites YbFe{sub 4}Sb{sub 12} and LaFe{sub 4}Sb{sub 12} investigated through {sup 121}Sb nuclear quadrupole and {sup 139}La nuclear magnetic resonance measurements

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, A; Iemura, S; Wada, S [Department of Physics, Graduate School of Science, Kobe University, Kobe 657-8501 (Japan); Ishida, K [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Shirotani, I; Sekine, C [Faculty of Engineering, Muroran Institute of Technology, Mizumoto, Muroran 050-8585 (Japan)

    2008-05-14

    We have elucidated low-energy spin fluctuations in the new filled skutterudites YbFe{sub 4}Sb{sub 12} and LaFe{sub 4}Sb{sub 12} synthesized at high pressures, through {sup 121}Sb nuclear quadrupole resonance (NQR) and {sup 139}La nuclear magnetic resonance (NMR) measurements. The longitudinal spin-lattice relaxation rate 1/T{sub 1} of {sup 121}Sb in YbFe{sub 4}Sb{sub 12} provides evidence that upon cooling below {approx}20 K, the compound transforms from the localized 4f electron state of Yb{sup 3+} ions to a nonmagnetic heavy Fermi liquid state, originating from the mixing of 4f electrons with conduction electrons. Whereas, the Curie-Weiss type behaviour of the {sup 139}La Knight shift and {sup 121}Sb- 1/T{sub 1} in LaFe{sub 4}Sb{sub 12} indicate that the compound remains in the localized electron state down to 1.4 K, it in fact originates from 3d electrons of Fe in [Fe{sub 4}Sb{sub 12} ] anions. In both compounds, the transversal nuclear spin-spin relaxation rate 1/T{sub 2} exhibits a clear peak at T*{approx_equal}32 and {approx_equal}23K respectively. The origin of the 1/T{sub 2} peak is discussed in terms of the freezing of the thermal vibration of Sb cages or rare-earth ions filled in each Sb cage. By comparing the experimental results of the present study with those previously reported for the compounds synthesized at ambient pressure, it is pointed out that both the strongly correlated electron properties and the thermal vibrations are greatly modified with the increase of rare-earth atom deficiency.

  5. Effect of Sb and As spray on emission characteristics of InAs quantum dots with AlAs capping layer

    Science.gov (United States)

    Zhang, Z.; Tan, S.; Kim, Y.; Liu, Z.; Reece, P. J.; Bremner, S. P.

    2017-10-01

    We report on the influence of an Sb/As combined spray on the physical and optical characteristics of AlAs-capped InAs/GaAs quantum dots grown by Molecular Beam Epitaxy. Photoluminescence emission from the quantum dots shows a significant peak position shift under different Sb/As spray sequences. A blue-shifted quantum dot emission peak with an initial Sb rest indicates a large-to-small quantum dots transition process, with a bi-modal quantum dot size distribution inferred. High-resolution Transmission Electron Microscopy results reveal a large density of small quantum dots when the Sb spray is treated first. Furthermore, defect passivation in the vicinity of the quantum dots by use of Sb spray was detected.

  6. Brief Review of Epitaxy and Emission Properties of GaSb and Related Semiconductors

    Directory of Open Access Journals (Sweden)

    Shouzhu Niu

    2017-11-01

    Full Text Available Groups III–V semiconductors have received a great deal of attention because of their potential advantages for use in optoelectronic and electronic applications. Gallium antimonide (GaSb and GaSb-related semiconductors, which exhibit high carrier mobility and a narrow band gap (0.725 eV at 300 K, have been recognized as suitable candidates for high-performance optoelectronics in the mid-infrared range. However, the performances of the resulting devices are strongly dependent on the structural and emission properties of the materials. Enhancement of the crystal quality, adjustment of the alloy components, and improvement of the emission properties have therefore become the focus of research efforts toward GaSb semiconductors. Molecular beam epitaxy (MBE is suitable for the large-scale production of GaSb, especially for high crystal quality and beneficial optical properties. We review the recent progress in the epitaxy of GaSb materials, including films and nanostructures composed of GaSb-related alloys and compounds. The emission properties of these materials and their relationships to the alloy components and material structures are also discussed. Specific examples are included to provide insight on the common general physical and optical properties and parameters involved in the synergistic epitaxy processes. In addition, the further directions for the epitaxy of GaSb materials are forecasted.

  7. Crystal structure control in Au-free self-seeded InSb wire growth

    Energy Technology Data Exchange (ETDEWEB)

    Mandl, Bernhard; Dick, Kimberly A; Deppert, Knut [Department of Solid State Physics, Lund University, S-22 100 Lund (Sweden); Kriegner, Dominik; Keplinger, Mario; Bauer, Guenther; Stangl, Julian, E-mail: Bernhard.Mandl@jku.at [Institute of Solid State- and Semiconductor Physics, Johannes Kepler University Linz, A-4040 Linz (Austria)

    2011-04-08

    In this work we demonstrate experimentally the dependence of InSb crystal structure on the ratio of Sb to In atoms at the growth front. Epitaxial InSb wires are grown by a self-seeded particle assisted growth technique on several different III-V substrates. Detailed investigations of growth parameters and post-growth energy dispersive x-ray spectroscopy indicate that the seed particles initially consist of In and incorporate up to 20 at.% Sb during growth. By applying this technique we demonstrate the formation of zinc-blende, 4H and wurtzite structure in the InSb wires (identified by transmission electron microscopy and synchrotron x-ray diffraction), and correlate this sequential change in crystal structure to the increasing Sb/In ratio at the particle-wire interface. The low ionicity of InSb and the large diameter of the wire structures studied in this work are entirely outside the parameters for which polytype formation is predicted by current models of particle seeded wire growth, suggesting that the V/III ratio at the interface determines crystal structure in a manner well beyond current understanding. These results therefore provide important insight into the relationship between the particle composition and the crystal structure, and demonstrate the potential to selectively tune the crystal structure in other III-V compound materials as well.

  8. Dielectric and piezoelectric properties of Bi0⋅ 5 (Na0⋅ 82K0⋅ 18) 0 ...

    Indian Academy of Sciences (India)

    The (1–)Bi0.5(Na0.82K0.18)0.5TiO3–LiSbO3 ( = 0−0.03) lead-free piezoelectric ceramics were fabricated by a conventional solid-state reaction method and the effect of LiSbO3 addition on microstructure and electrical properties of the ceramics was investigated. The results of XRD measurement show that Li+ and ...

  9. MOVPE deposition of Sb2Te3 and other phases of Sb-Te system on sapphire substrate

    Science.gov (United States)

    Kuznetsov, P. I.; Shchamkhalova, B. S.; Yapaskurt, V. O.; Shcherbakov, V. D.; Luzanov, V. A.; Yakushcheva, G. G.; Jitov, V. A.; Sizov, V. E.

    2017-08-01

    The films of Sb-Te system have been deposited by MOVPE on (0 0 0 1) Al2O3 substrates with thin ZnTe buffer layers at different temperatures and Te/Sb ratios in the vapor phase. X-ray diffractometry, SEM microscopy, Raman and EDX spectroscopy were used to study as-grown films. The surface morphology and stoichiometry of Sb-Te films strongly depend on Te/Sb ratio in vapor phase. We have deposited the phases of homologous series nSb2·mSb2Te3 with following stoichiometries: Sb2Te3, Sb4Te5, Sb8Te9, Sb10Te9, Sb4Te3, Sb2Te, Sb8Te3, Sb10Te3, Sb16Te3, Sb18Te3 and Sb. Transport properties of Sb2Te3, Sb4Te5, Sb8Te9, Sb4Te3, Sb2Te were evaluated using Van der Pauw technique at 300 K.

  10. Study on the synthesis and formation mechanism of flower-like Cu{sub 3}SbS{sub 4} particles via microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Guilin, E-mail: glchen@fjnu.edu.cn [Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials, College of Physics and Energy, Fujian Normal University, Fuzhou, 350007 (China); Fujian Provincial Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen, 361005 (China); Wang, Weihuang; Zhao, Jifu; Yang, Wenyu [Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials, College of Physics and Energy, Fujian Normal University, Fuzhou, 350007 (China); Chen, Shuiyuan; Huang, Zhigao [Fujian Provincial Key Laboratory of Quantum Manipulation and New Energy Materials, College of Physics and Energy, Fujian Normal University, Fuzhou, 350007 (China); Fujian Provincial Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Xiamen, 361005 (China); Jian, Rongkun; Ruan, Huirong [Department of Materials Science and Engineering, Fujian Normal University, Fuzhou, 350007 (China)

    2016-09-15

    The future development of Cu{sub 3}SbS{sub 4} as an alternative absorber for low cost and high efficiency thin film solar cell depends strongly on the understanding of the formation of mechanism in this system. With this aim, a detailed characterization of Cu{sub 3}SbS{sub 4} particles prepared by microwave irradiation is presented, combining XRD, SEM, and EDX. The development of Cu{sub 3}SbS{sub 4} formation with the increasement of temperature and the prolongation of time are investigated by depth-resolved analysis. Under such conditions, a reaction pathway for the formation of Cu{sub 3}SbS{sub 4} from binary and CuSbS{sub 2} compounds as intermediates is proposed. The experimental data supports a formation mechanism of Cu{sub 3}SbS{sub 4} that proceeds rapidly when the CuSbS{sub 2} react with the remaining binary phases CuS. During reaction Cu is completely consumed, while Sb is lost through the way of Sb{sub 2}S{sub 3} vapor. - Highlights: • Flower-like Cu{sub 3}SbS{sub 4} particles were synthesized by microwave irradiation route. • A series of time-dependent experiments were designed to study the growth mechanism of the Cu{sub 3}SbS{sub 4}. • During reaction, the phase content transitions from rich-Sb{sub 2}S{sub 3} and CuS, through to CuSbS{sub 2}, and finally Cu{sub 3}SbS{sub 4}. • This work provides a solid platform for further preparation of pure Cu{sub 3}SbS{sub 4}.

  11. The electronic structure of MnBi

    NARCIS (Netherlands)

    Coehoorn, R.; Groot, R.A. de

    1985-01-01

    The first self-consistent spin-polarised band-structure calculation of the ferromagnetic compound MnBi in its low-temperature phase has been performed. The spin-orbit interaction was treated as a perturbation using scalar-relativistic wavefunctions. On the Mn atoms an effective 3d5.5 configuration

  12. Design and Simulated Characteristics of Nanosized InSb Based Heterostructure Devices

    Directory of Open Access Journals (Sweden)

    T. D. Subash

    2014-01-01

    Full Text Available Indium antimonide nanoparticles were synthesized at room temperature. X-ray diffraction measurements are utilized to characterize the nanocomposites. The InSb nanoparticle has an average particle size in a range of 47 mm to 99 mm which is observed using the XRD result. The InSb is a material which is used to design the transistor. For designing purpose the simulator TCAD is used, by which the HEMT device is structured and its performance is analyzed and it is found that transistor operates as normal devices. This designed device is more valuable since a nanocomposite InSb material is used as a channel in HEMT device, thereby leading to the nanosized HEMT device. In addition, InSb has the property of high saturation velocity and mobility which results in higher performance of the device than any other materials in III-V compounds.

  13. A double-blind study of SB-220453 (Tonerbasat) in the glyceryltrinitrate (GTN) model of migraine

    DEFF Research Database (Denmark)

    Tvedskov, Jesper Filtenborg; Iversen, H K; Olesen, J

    2004-01-01

    , scored 0-10, was registered for 12 h, and fulfillment of International Headache Society (IHS) criteria was recorded until 24 h. Four subjects had a hypotensive episode after SB-220453 plus GTN but none after GTN alone. The reaction was unexpected, since animal models and previous human studies had shown......The need for experimental migraine models increases as therapeutic options widen. In the present study, we investigated SB-220453 for efficacy in the glyceryltrinitrate (GTN) human experimental migraine model. SB-220453 is a novel benzopyran compound, which in animal models inhibits neurogenic...... towards reduction after SB-220453 compared with placebo (median 4 vs. 7, P = 0.15). However, no reduction was seen in the number of subjects experiencing delayed headache (8 vs. 8), number of subjects reporting migraine (6 vs. 8), migraine attacks fulfilling IHS criteria 1.1 or 1.7 (6 vs. 7) or IHS 1...

  14. A model for the composition modifications in the Cu-Sb-O system

    Energy Technology Data Exchange (ETDEWEB)

    Stan, M.

    1997-05-01

    THE SN-SB-CU-O SYSTEM HAS BEEN EXTENSIVELY STUDIED BUT SYSTEMATIC PHASE EQUILIBRIUM STUDIES HAVE NOT BEEN APPROACHED. THE SYSTEM CONTAINS USEFUL CERAMICS WITH SPECIFIC ELECTRICAL AND MAGNETIC PROPERTIES, EMPLOYED AS SENSORS, ELECTRODES AND CATALYSTS. AS A PRELIMINARY STEP TO THE PHASE DIAGRAM CALCULATION, THE PAPER AIMS TO PRESENT A MODEL FOR THE COMPOSITION MODIFICATIONS IN THE CU-SB-O SYSTEM, WHICH IS THE MOST COMPLEX OF ALL SUBSYSTEMS. EXOTHERMIC EFFECTS ALONG WITH MASS INCREASES CAN BE OBSERVED IN DTA/GA CURVES, WERE ASSIGNED, FOR ALL SAMPLES, TO SB2O3 AND SB2O4 OXIDATION AND TO CUSB2O6 FORMATION: (1) APPROX. EQUAL 500 DIG C SB2O3 + 1/2 O2 DOUBLE RIGHT ARROW SB2O4; (2) {gt} 750 DIG C SB2O4 + CUO + 1/2 O2 DOUBLE RIGHT ARROW CUSB2O6. FOR THE SAMPLES HAVING CUO IN EXCESS, THE REDUCTION OF CUO TO CUO AND THE FORMATION OF THE CU4SBO4.5 COMPOUND SIMULTANEOUSLY OCCUR: {gt} 950 dig C CUSB2O6 + 7CuO double right arrow (1-r) CUSB2O6+7(1-r)cow+ 2rCu4SbO4.5 + 2rO2 where rEpsilon (0, 1) is the fraction of CUSB2O6 that transforms into Cu4SbO4.5. All the experimental evidences show that the Equations (1), (2) and (3) are good descriptions of the transformations that occurs in the CuO-Sb2O3 system along with the temperature. If the reactions are considered as completed, including a=1 in IQ. (3), then the quantity of oxygen that is gained or lost can be calculated for each sample. It is important to note that Equations (2) and (3) should be carefully solved because of the excess quantities of cow or SB2O4 that can be found in some samples. The calculated values of mass variation are in a good agreement with those obtained from the experimental GT diagrams. The atomic fractions of Cu, Sb and Awe content change in the system and they can be also calculated. The model assumes that at room temperature the compositions lay on the CuO-Sb2O3 line as shown in Fig. 1.

  15. Development in Zn4Sb-based thermoelectric materials

    DEFF Research Database (Denmark)

    Yin, Hao

    Thermoelectric material, as a functional material which has the dual ability of electrical-thermal energy conversion, has attracted tremendous interests in the last decades, especially against the background of global energy shortage and surging of new materials. The present work focuses...... on the notable Zn4Sb3, with the effort to further the basic understanding of the compound, as well as improve the thermoelectric performance to meet the commercial use. The maximum efficiency of a thermoelectric material is determined by its figure of merit, zT=TS2/ where S is the Seebeck coefficient...... or thermopower,  the electrical conductivity, the thermal conductivity and T the absolute temperature. The best thermoelectrics are heavily doped semiconductors with high thermoelectric power factors and low thermal conductivities, known as “Phonon Glasses Electrical Crystals”. Zn4Sb3 is one such material...

  16. The fire ant social chromosome supergene variant Sb shows low diversity but high divergence from SB.

    Science.gov (United States)

    Pracana, Rodrigo; Priyam, Anurag; Levantis, Ilya; Nichols, Richard A; Wurm, Yannick

    2017-06-01

    Variation in social behaviour is common, yet little is known about the genetic architectures underpinning its evolution. A rare exception is in the fire ant Solenopsis invicta: Alternative variants of a supergene region determine whether a colony will have exactly one or up to dozens of queens. The two variants of this region are carried by a pair of 'social chromosomes', SB and Sb, which resemble a pair of sex chromosomes. Recombination is suppressed between the two chromosomes in the supergene region. While the X-like SB can recombine with itself in SB/SB queens, recombination is effectively absent in the Y-like Sb because Sb/Sb queens die before reproducing. Here, we analyse whole-genome sequences of eight haploid SB males and eight haploid Sb males. We find extensive SB-Sb differentiation throughout the >19-Mb-long supergene region. We find no evidence of 'evolutionary strata' with different levels of divergence comparable to those reported in several sex chromosomes. A high proportion of substitutions between the SB and Sb haplotypes are nonsynonymous, suggesting inefficacy of purifying selection in Sb sequences, similar to that for Y-linked sequences in XY systems. Finally, we show that the Sb haplotype of the supergene region has 635-fold less nucleotide diversity than the rest of the genome. We discuss how this reduction could be due to a recent selective sweep affecting Sb specifically or associated with a population bottleneck during the invasion of North America by the sampled population. © 2017 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  17. Mo(3)Sb(7-x)Te(x) for Thermoelectric Power Generation

    Science.gov (United States)

    Snyder, G. Jeffrey; Gascoin, Frank S.; Rasmussen, Julia

    2009-01-01

    Compounds having compositions of Mo(3)Sb(7-x)Te(x) (where x = 1.5 or 1.6) have been investigated as candidate thermoelectric materials. These compounds are members of a class of semiconductors that includes previously known thermoelectric materials. All of these compounds have complex crystalline and electronic structures. Through selection of chemical compositions and processing conditions, it may be possible to alter the structures to enhance or optimize thermoelectric properties.

  18. The atomistic mechanism for Sb segregation and As displacement of Sb in InSb(001) surfaces

    Science.gov (United States)

    Anderson, Evan M.; Millunchick, Joanna M.

    2018-01-01

    Interfacial broadening occurs in mixed-anion alloy heterostructures such as InAs/InAsSb due to both Sb-segregation and As-for-Sb exchange. In order to determine the atomistic mechanisms for these processes, we conduct ab initio calculations coupled with a cluster expansion formalism to determine the surface reconstructions of the pure and As-exposed InSb(001) surfaces. This approach provides a predicted phase diagram for pure InSb that is in better agreement with experiments. Namely, the α2(2 × 4) and α3c(4 × 4) structures are ultimately stable at 0K, but the α(4 × 3) and α2c(2 × 6) are within 1 meV/Å2. Exposure of the InSb(001) surface to As results in the As atoms infiltrating into the crystal and displacing subsurface Sb, thus providing the atomistic mechanisms for experimental observations of the As-for-Sb exchange reaction and Sb segregation. Experiments show that the widely reported A-(1 × 3) reconstruction is actually comprised of multiple reconstructions, which is consistent with the prediction of several nearly stable possible reconstructions.

  19. Large magnetoresistance of MnBi/Bi/MnBi spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Tarawneh, Khaldoun, E-mail: Khaldoun@psut.edu.jo [Princess Sumaya University for Technology, Amman 11941 (Jordan); Al-Aqtash, Nabil; Sabirianov, Renat [University of Nebraska at Omaha, Omaha, NE 68182 (United States)

    2014-08-01

    A transport magetoresistance (MR) of MnBi/Bi/MnBi spin valve device was calculated using density functional theory coupled with nonequilibrium Green's function method. The calculated transmission MR of the MnBi/Bi/MnBi spin valve device is around 750%, Obtained MR is very large compared with MR observed experimentally in MnBi junctions at room temperature (MR∼70%). Large MR is consistent with a large transport spin polarization was demonstrated in MnBi films by the point contact Andreev reflection spectroscopy. MR of experimental point contacts is observed to be low is probably due to the rough interfaces that increased scattering and contact resistance. Consequently, a spin-valve MnBi/Bi/MnBi device could potentially have large MR that could be controlled by varying the thickness of the Bi spacer. Thus, MnBi is a promising candidate for high MR devices with tunable spacer properties. - Highlights: • We calculate the transport magetoresistance (MR) of MnBi/Bi/MnBi spin valve device. • The calculated transmission MR of the MnBi/Bi/MnBi spin valve device is around 750%. • MR depend on the thickness of Bi layer. • MnBi is a promising candidate for high MR devices using spin polarizing current.

  20. Magnetic, electrochemical and thermoelectric properties of P 2 -Nax (Co7/8Sb1/8)O2

    Science.gov (United States)

    Assadi, M. H. N.; Li, S.; Zheng, R. K.; Ringer, S. P.; Yu, A. B.

    2017-11-01

    We theoretically investigated the electronic, electrochemical and magnetic properties of Sb doped NaxCoO2 (x = 1, 0.75 and 0.50). SbCo dopants adopt 5+ oxidation state in NaxCoO2 host lattice for all Na concentrations (x). Due to high oxidation states, Sb5+ strongly repels Na ions and therefore it decreases the Na+/Na electrochemical potential. The electrons introduced by Sb5+ localize on nearby Co ions creating Co2+ species which are absent in undoped NaxCoO2. Co2+ ions reduce the spin entropy flow decreasing the Seebeck coefficient in the Sb doped compounds. The results can be generalized to other dopants with high oxidation state.

  1. Electrical properties of GaSb/InAsSb core/shell nanowires.

    Science.gov (United States)

    Ganjipour, Bahram; Sepehri, Sobhan; Dey, Anil W; Tizno, Ofogh; Borg, B Mattias; Dick, Kimberly A; Samuelson, Lars; Wernersson, Lars-Erik; Thelander, Claes

    2014-10-24

    Temperature dependent electronic properties of GaSb/InAsSb core/shell and GaSb nanowires have been studied. Results from two-probe and four-probe measurements are compared to distinguish between extrinsic (contact-related) and intrinsic (nanowire) properties. It is found that a thin (2-3 nm) InAsSb shell allows low barrier charge carrier injection to the GaSb core, and that the presence of the shell also improves intrinsic nanowire mobility and conductance in comparison to bare GaSb nanowires. Maximum intrinsic field effect mobilities of 200 and 42 cm(2) Vs(-1) were extracted for the GaSb/InAsSb core/shell and bare-GaSb NWs at room temperature, respectively. The temperature-dependence of the mobility suggests that ionized impurity scattering is the dominant scattering mechanism in bare GaSb while phonon scattering dominates in core/shell nanowires. Top-gated field effect transistors were fabricated based on radial GaSb/InAsSb heterostructure nanowires with shell thicknesses in the range 5-7 nm. The fabricated devices exhibited ambipolar conduction, where the output current was studied as a function of AC gate voltage and frequency. Frequency doubling was experimentally demonstrated up to 20 kHz. The maximum operating frequency was limited by parasitic capacitance associated with the measurement chip geometry.

  2. The Sandbridge SB3011 Platform

    Directory of Open Access Journals (Sweden)

    Daniel Iancu

    2007-03-01

    Full Text Available This paper describes the Sandbridge Sandblaster real-time software-defined radio platform. Specifically, we describe the SB3011 system-on-a-chip multiprocessor. We describe the software development system that enables real-time execution of communications and multimedia applications. We provide results for a number of interesting communications and multimedia systems including UMTS, DVB-H, WiMAX, WiFi, and NTSC video decoding. Each processor core achieves 600 MHz at 0.9 V operation while typically dissipating 75 mW in 90 nm technology. The entire chip typically dissipates less than 500 mW at 0.9 V.

  3. Thermoelectric properties of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 skutterudites prepared by HPHT method

    Directory of Open Access Journals (Sweden)

    Kong Lingjiao

    2017-10-01

    Full Text Available N-type polycrystalline skutterudite compounds Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 with the bcc crystal structure were synthesized by high pressure and high temperature (HPHT method. The synthesis time was sharply reduced to approximately half an hour. Typical microstructures connected with lattice deformations and dislocations were incorporated in the samples of Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 after HPHT. Electrical and thermal transport properties were meticulously researched in the temperature range of 300 K to 700 K. The Fe0.2Ni0.15Co3.65Sb12 sample shows a lower thermal conductivity than that of Ni0.15Co3.85Sb12. The dimensionless thermoelectric figure-of-merit (zT reaches the maximal values of 0.52 and 0.35 at 600 K and 700 K respectively, for Ni0.15Co3.85Sb12 and Fe0.2Ni0.15Co3.65Sb12 samples synthesized at 1 GPa.

  4. Dynamic reconfiguration of van der Waals gaps within GeTe-Sb2Te3based superlattices.

    Science.gov (United States)

    Momand, Jamo; Wang, Ruining; Boschker, Jos E; Verheijen, Marcel A; Calarco, Raffaella; Kooi, Bart J

    2017-06-29

    Phase-change materials based on GeSbTe show unique switchable optoelectronic properties and are an important contender for next-generation non-volatile memories. Moreover, they recently received considerable scientific interest, because it is found that a vacancy ordering process is responsible for both an electronic metal-insulator transition and a structural cubic-to-trigonal transition. GeTe-Sb 2 Te 3 based superlattices, or specifically their interfaces, provide an interesting platform for the study of GeSbTe alloys. In this work such superlattices have been grown with molecular beam epitaxy and they have been characterized extensively with transmission electron microscopy and X-ray diffraction. It is shown that the van der Waals gaps in these superlattices, which result from vacancy ordering, are mobile and reconfigure through the film using bi-layer defects and Ge diffusion upon annealing. Moreover, it is shown that for an average composition that is close to GeSb 2 Te 4 a large portion of 9-layered van der Waals systems is formed, suggesting that still a substantial amount of random vacancies must be present within the trigonal GeSbTe layers. Overall these results illuminate the structural organization of van der Waals gaps commonly encountered in GeSbTe alloys, which are intimately related to their electronic properties and the metal-insulator transition.

  5. Ferromagnetism in Cr-doped topological insulator TlSbTe2

    Directory of Open Access Journals (Sweden)

    Zhiwei Wang

    2015-08-01

    Full Text Available We have synthesized a new ferromagnetic topological insulator by doping Cr to the ternary topological-insulator material TlSbTe2. Single crystals of Tl1−xCrxSbTe2 were grown by a melting method and it was found that Cr can be incorporated into the TlSbTe2 matrix only within the solubility limit of about 1%. The Curie temperature θC was found to increase with the Cr content but remained relatively low, with the maximum value of about 4 K. The easy axis was identified to be the c-axis and the saturation moment was 2.8 μB (Bohr magneton at 1.8 K. The in-plane resistivity of all the samples studied showed metallic behavior with p-type carriers. Shubnikov-de Hass oscillations were observed in samples with the Cr-doping level of up to 0.76%. We also tried to induce ferromagnetism in TlBiTe2 by doping Cr, but no ferromagnetism was observed in Cr-doped TlBiTe2 crystals within the solubility limit of Cr which turned out to be also about 1%.

  6. Tunnel switch diode based on AlSb/GaSb heterojunctions

    OpenAIRE

    Cheng, X.-C.; Cartoixà, X.; Barton, M. A.; Hill, C. J.; McGill, T. C.

    2000-01-01

    We report on tunnel switch diodes based on AlSb barriers and GaSb p–n junctions grown by molecular beam epitaxy. These were the devices with thyristor like switching in the GaSb/AlSb system. The characteristic "S" shaped current–voltage curve was found to occur for structures with AlSb barriers less than 300 Å thick. The switching voltage and current density exhibited less sensitivity to barrier and epilayer thickness than was predicted by the punch-through model. The results were correlated ...

  7. Design of a Thermoelectric Material Using the CALPHAD Technique: Thermodynamic Reassessment of the Al-Sb-Zn System

    Science.gov (United States)

    Wang, Wei; Yang, Lili; Wang, Nan; Zhang, Haifeng; Jia, Yanping

    2017-09-01

    The β-Sb3Zn4 intermetallic compound, one of the most promising thermoelectric materials in the mid-1990s, has attracted much interest due to its high thermoelectric performance in the intermediate temperature range. To improve the thermoelectric properties of the compound β-Sb3Zn4, Al doping is an effective method. Therefore, accurate theoretical analysis of the Al-Sb-Zn system is essential for the design of such thermoelectric materials. In this work, the Al-Sb-Zn system was reassessed by means of the calculation of phase diagram (CALPHAD) technique. A set of self-consistent thermodynamic parameters was obtained and can be used to extrapolate to related high-order systems. Some phase equilibria and thermochemical properties can be predicted using the present thermodynamic description.

  8. Improvement of Microstructure and Wear Property of Al-Bi Alloys by Nd Addition

    Science.gov (United States)

    Man, Tiannan; Zhang, Lin; Xiang, Zhaolong; Wang, Wenbin; Huang, Minghao; Wang, Engang

    2017-10-01

    The fabrication of immiscible alloys with a homogeneous microstructure remains a challenge owing to the liquid-liquid phase separation. The microstructure and mechanical properties of Al-Bi immiscible alloys with the addition of rare-earth Nd are investigated in this work. Scanning electron microscopy analyses show the formation of intermetallic compound NdBi2 during solidification. The rod-like NdBi2 compounds act as heterogeneous nucleation sites for the Bi-rich droplets, which impedes the segregation of the Bi phase and refines the microstructure of the Al-Bi alloys. The results of a wear test show that the addition of Nd in Al-Bi immiscible alloys results in improved wear resistance, which is useful for the development of high-performance self-lubrication materials.

  9. Optical parameters of diode lasers based on an InAsSb/InAsSbP heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Astakhova, A. P. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Bez' yazychnaya, T. V. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus); Burov, L. I.; Gorbatsevich, A. S.; Ryabtsev, A. G. [Belarussian State University (Belarus); Ryabtsev, G. I. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus); Shchemelev, M. A. [Belarussian State University (Belarus); Yakovlev, Yu. P., E-mail: Yak@iropt1.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

    2008-02-15

    The rates of radiative recombination (including transitions induced by enhanced luminescence) and nonradiative recombination, internal quantum yield of luminescence, and the matrix element for band-to-band optical transitions were determined for the first time for InAsSb/InAsSbP diode lasers oscillating at wavelengths of 3.1-3.2 {mu}m. It is established that the contribution of nonradiative recombination to the lasing threshold can be as large as 97%. The internal quantum yield of luminescence for the InAs{sub 0.97}Sb{sub 0.03} compound is no higher than 3%. Most likely, the nonradiative channel is formed with involvement of Auger recombination with the constant C = 4.2 Multiplication-Sign 10{sup -38} m{sup 6}s{sup -1} (T = 77 K). The studied samples of lasers feature relatively low optical losses {rho} = 900 m{sup -1} and internal quantum efficiency of emission at the level of 0.6. The spontaneous lifetime of nonequilibrium charge carriers as determined from the radiative-recombination rate is equal to 6 Multiplication-Sign 10{sup -8} s, which is consistent with known published data.

  10. Band Structure and Fermi Surface of Cu2Sb by the LMTO Method

    DEFF Research Database (Denmark)

    Jan, J. P.; Skriver, Hans Lomholt

    1977-01-01

    The linear muffin-tin orbital (LMTO) method of bandstructure calculation has been applied to the simple tetragonal compound Cu2Sb. The d bands of Cu lie substantially below the Fermi level, and the Fermi surface is a recognizable distortion of the free-electron model. The Fermi surface has sheets...

  11. Exploratory Bi-Factor Analysis

    Science.gov (United States)

    Jennrich, Robert I.; Bentler, Peter M.

    2011-01-01

    Bi-factor analysis is a form of confirmatory factor analysis originally introduced by Holzinger. The bi-factor model has a general factor and a number of group factors. The purpose of this article is to introduce an exploratory form of bi-factor analysis. An advantage of using exploratory bi-factor analysis is that one need not provide a specific…

  12. New sulfido antimonates of the heavy alkali metals. Synthesis, crystal structure and chemical bonding of (K/Rb/Cs){sub 3}SbS{sub 3} and Cs{sub 3}SbS{sub 4} . H{sub 2}O; Neue Sulfido-Antimonate der schweren Alkalimetalle. Synthese, Kristallstruktur und chemische Bindung von (K/Rb/Cs){sub 3}SbS{sub 3} und Cs{sub 3}SbS{sub 4} . H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Lisa V.; Schwarz, Michael; Roehr, Caroline [Freiburg Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2013-12-15

    The new sulfido antimonates(III) (Rb/Cs){sub 3}SbS{sub 3} were prepared from the alkali metal sulfides Rb{sub 2}S/Cs{sub 2}S{sub 2} and elemental antimony and sulfur or Sb{sub 2}S{sub 3} at reaction temperatures of about 700 C. The known isotypic potassium compound was similarly synthesized from the elements. The structures of the light-yellow crystals were refined using single-crystal X-ray data. Both compounds are isotypic to the respective Na salt forming the Na{sub 3}AsS{sub 3} structure type (cubic, space group P2{sub 1}3, K/Rb/Cs: a = 947.21(7)/982.28(5)/1025.92(5) pm, Z = 4, R1 = 0.0159/0.0560/0.0582). The {psi}-tetrahedral SbS{sub 3}{sup 3-} anions with Sb-S bond lengths of 242 pm are arranged in a cubic face centered packing, in which the three crystallographically different A{sup +} cations occupy the tetrahedral and octahedral voids, overall exhibiting a distorted octahedral sulfur coordination. The chemical bonding and the characteristics of the stereochemically active lone electron pair have been investigated by means of FP-LAPW band structure calculations. Needle-shaped crystals of the monohydrate of the antimony(V) salt Cs{sub 3}SbS{sub 4} . H{sub 2}O were obtained from a suspension of Sb{sub 2}O{sub 3}, CsOH and elemental sulfur. Cs{sub 3}SbS{sub 4} . H{sub 2}O crystallizes in a new structure type (monoclinic, space group P2{sub 1}/c, a = 987.17(10), b = 994.83(7), c = 1600.46(14) pm, {beta} = 126.895(8) , Z = 4, R1 = 0.0234). As expected, the Sb-S distances (233.1-234.7 pm) in the nearly ideally tetrahedral anion SbS{sub 4}{sup 3-} are considerably shorter than in the antimonates(III) but match the bond lengths in the anhydrous sulfido antimonate(V) Cs{sub 3}SbS{sub 4}. Due to their similar fcc-like anion packing and the stereochemically active lone electron pair of Sb in the antimonates(III), the whole series of compounds A{sub 3}Sb{sup III,V}S{sub 3/4} shows a uniform structure relation, which is elucidated using crystallographic group

  13. Exploratory Bi-factor Analysis

    OpenAIRE

    Jennrich, Robert I.; Bentler, Peter M.

    2011-01-01

    Bi-factor analysis is a form of confirmatory factor analysis originally introduced by Holzinger. The bi-factor model has a general factor and a number of group factors. The purpose of this paper is to introduce an exploratory form of bi-factor analysis. An advantage of using exploratory bi-factor analysis is that one need not provide a specific bi-factor model a priori. The result of an exploratory bi-factor analysis, however, can be used as an aid in defining a specific bi-factor model. Our ...

  14. On atomic mechanisms governing the oxidation of Bi2Te3.

    Science.gov (United States)

    Music, Denis; Chang, Keke; Schmidt, Paul; Braun, Felix N; Heller, Martin; Hermsen, Steffen; Pöllmann, Peter J; Schulzendorff, Till; Wagner, Cedric

    2017-10-18

    Oxidation of Bi2Te3 (space group R-3m) has been investigated using experimental and theoretical means. Based on calorimetry, x-ray photoelectron spectroscopy and thermodynamic modelling, Bi2Te3 is at equilibrium with Bi2O3 and TeO2, whereby the most stable compound is Bi2Te3, followed by Bi2O3. Hence, the reactivity of Bi towards oxygen is expected to be higher than that of Te. This notion is supported by density functional theory. The strongest bond is formed between Bi and Te, followed by Bi - O. This gives rise to unanticipated atomic processes. Dissociatively adsorbed oxygen diffuses through Bi and Te basal planes of Bi2Te3(0001) and preferably interacts with Bi. The Te termination considerably retards this process. These findings may clarify conflicting literature data. Any basal plane off-cut or Bi terminations trigger oxidation, but a perfect basal cleavage, where only Te terminations are exposed to air, may be stable for a longer period of time. These results are of relevance for applications in which surfaces are of key importance, such as nanostructured Bi2Te3 thermoelectric devices. © 2017 IOP Publishing Ltd.

  15. Solution route synthesis of InSb, Cu{sub 6}Sn{sub 5} and Cu{sub 2}Sb electrodes for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sarakonsri, T.; Hackney, S.A. [Department of Metallurgical and Materials Engineering, Michigan Technological University, Houghton, MI 49931 (United States); Johnson, C.S.; Thackeray, M.M. [Electrochemical Technology and Basic Sciences Program, Chemical Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2006-02-28

    A solution method was used to prepare InSb, Cu{sub 6}Sn{sub 5} and Cu{sub 2}Sb intermetallic compounds that are of interest as negative electrode materials for lithium batteries. The compounds were synthesized by the reduction of dissolved transition metal- and metalloid salts with fine Zn powder. Heterogeneous redox reactions at the surface of the Zn particles resulted in fern-like dendritic structures with high surface areas. Powder X-ray diffraction and lattice imaging by transmission electron microscopy showed that the intermetallic products were highly crystalline with preferred crystallographic orientations. Mild heat-treatment of the products under argon improved their phase purity. Electrodes prepared by this method exhibited a large irreversible capacity loss on the first charge/discharge cycle. Cu{sub 2}Sb electrodes showed the greatest cycling stability; after the initial cycle, they delivered more than 230mAhg{sup -1} when cycled between 1.2 and 0.0V versus metallic lithium, consistent with previously reported data for ball-milled Cu{sub 2}Sb electrodes. (author)

  16. Mechanism of Pb and Sb role on the 2223 phase of BSCCO system superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Sukirman, E.; Sulisworo, P.; Prasuad, W.; Wuryanto [Material Science Research Centre, National Atomic Energy Agency, Kawasan Puspiptek Serpong Tangerang (Indonesia)

    1998-10-01

    The mechanism of Pb and Sb role on the 2223 phase of Bi-Sr-Ca-Cu-O (BSCCO) system superconductor has been investigated. The 2223 phase samples without doping and with doping: Pb, and Sb have been synthesized by solid state reaction method. The samples characterization have been carried out through a susceptibility-, resistivity-, neutron diffraction profile-, and microstructure measurements. Crystal structure of the samples have been analyzed using RIETAN software. The analysis results show that relative content of the 2223 phase increase from 28% in the non-doped sample (TDP) to 75% in Pb-doped (DPB) and 44% in Sb-doped (DSB) samples. When, Pb, or Sb enter into the 2223 phase crystal system, then the oxygen atoms on SrO layers shift toward the copper atoms position on Cu(2)O{sub 2} layers as far as 0.1(1) and 0.1(1) A in DPB, and DSB, respectively. BiO layers shift away from SrO layers as far as 0.3(1) and 0.1(1) A in DPB, and DSB, respectively. The critical current density Jc increase from 3 A/cm{sup 2} in TDP to 210 and 35 A/cm{sup 2} in DPB, and DSB, respectively. The onset point of Tc also increase from 99 K in TDP to 103 and 107 K in DPB and DSB, respectively. It is concluded that the enhancement of the 2223 phase, Jc and onset point are due to improvement on the structure stability, improvement on the connection between unit-cells, and shortening the apical oxygen-Cu chains, respectively. (author)

  17. The New Superconductor tP-SrPd2Bi2: Structural Polymorphism and Superconductivity in Intermetallics.

    Science.gov (United States)

    Xie, Weiwei; Seibel, Elizabeth M; Cava, Robert J

    2016-04-04

    We consider a system where structural polymorphism suggests the possible existence of superconductivity through the implied structural instability. SrPd2Bi2 has two polymorphs, which can be controlled by the synthesis temperature: a tetragonal form (CaBe2Ge2-type) and a monoclinic form (BaAu2Sb2-type). Although the crystallographic difference between the two forms may, at first, seem trivial, we show that tetragonal SrPd2Bi2 is superconducting at 2.0 K, whereas monoclinic SrPd2Bi2 is not. We rationalize this finding and place it in context with other 1-2-2 phases.

  18. First-principles comparison of the cubic and tetragonal phases of Mo3Sb7

    KAUST Repository

    Nazir, Safdar

    2011-03-01

    Using ab initio density functional based methods, we study the normal metal state properties of the ∼3 K Mo3Sb7 superconductor, in its high temperature cubic and low temperature tetragonal structures. Although the density of states at the Fermi energy is reasonably high in both structures, our calculations unequivocally show that there exists no long range magnetic ordering in this system. We also address the optical properties of the compound. The magnetism in Mo3Sb7 is studied by fixed spin moment calculations, which yield a shallow non-magnetic minimum, thus inferring propensity to a magnetic instability. © 2011 Elsevier B.V. All rights reserved.

  19. Direct electrodeposition of Cu2Sb for lithium-ion battery anodes.

    Science.gov (United States)

    Mosby, James M; Prieto, Amy L

    2008-08-13

    We describe the direct single potential electrodeposition of crystalline Cu2Sb, a promising anode material for lithium-ion batteries, from aqueous solutions at room temperature. The use of citric acid as a complexing agent increases the solubility of antimony salts and shifts the reduction potentials of copper and antimony toward each other, enabling the direct deposition of the intermetallic compound at pH 6. Electrodeposition of Cu2Sb directly onto conducting substrates represents a facile synthetic method for the synthesis of high quality samples with excellent electrical contact to a substrate, which is critical for further battery testing.

  20. Orbital-dependent Rashba coupling in bulk BiTeCl and BiTeI

    KAUST Repository

    Zhu, Zhiyong

    2013-02-06

    By all-electron ab initio calculations, the layered polar semiconductor BiTeCl is shown to host giant bulk Rashba spin splitting, similar to the recently reported compound BiTeI. In both materials, the standard Rashba–Bychkov model is no longer applicable, because of huge band extrema shifts even in the absence of spin–orbit coupling and a strong momentum dependence of the Rashba coupling constant (αR). By assuming αR to be orbital dependent, a phenomenological extension of the Rashba–Bychkov model is proposed which explains the splitting behavior of states with small in-plane momentum.

  1. High-Current GaSb/InAs(Sb) Nanowire Tunnel Field-Effect Transistors

    OpenAIRE

    Dey, Anil; Borg, Mattias; Ganjipour, Bahram; Ek, Martin; Dick Thelander, Kimberly; Lind, Erik; Thelander, Claes; Wernersson, Lars-Erik

    2013-01-01

    We present electrical characterization of GaSb/InAs(Sb) nanowire tunnel field-effect transistors. The broken band alignment of the GaSb/InAs(Sb) heterostructure is exploited to allow for interband tunneling without a barrier, leading to high ON-current levels. We report a maximum drive current of 310 μA/μm at Vds = 0.5 V. Devices with scaled gate oxides display transconductances up to gm = 250 mS/mm at Vds = 300 mV, which are normalized to the nanowire circumference at the axial heterojunction...

  2. IR cut filters for optoelectronic devices, based on CdSb, ZnSb single crystals

    Directory of Open Access Journals (Sweden)

    Ashcheulov A. A.

    2009-02-01

    Full Text Available Interference-adsorptive filters on the base of the CdSb and ZnSb semiconductor single crystals are proposed as a new type of cooling cut optical filters used in modern optoelectronics. Computer simulation of the structure of interference multilayer coatings has shown the availability of design and application of cut filters on CdSb with optimized parameters. Experimental results demonstrate high optical characteristics and mechanical strength of two-channel cut CdSb filters used in various devices.

  3. Hydrazine-hydrothermal syntheses, characterizations and photoelectrochemical properties of two quaternary chalcogenidoantimonates(III) BaCuSbQ{sub 3} (Q = S, Se)

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chang; Hou, Peipei [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Chai, Wenxiang [College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Tian, Jiawei; Zheng, Xuerong; Shen, Yaying; Zhi, Mingjia; Zhou, Chunmei [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Liu, Yi, E-mail: liuyimse@zju.edu.cn [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2016-09-15

    Two isostructural quaternary chalcogenidoantimonates(III) BaCuSbQ{sub 3} (Q = S, Se): BaCuSbS{sub 3} (1) and BaCuSbSe{sub 3} (2) have been successfully synthesized through a facile hydrazine-hydrothermal method. Both two compounds crystallize in the orthorhombic space group and feature a three-dimensional (3D) channeled [Cu{sub 2}Sb{sub 2}Q{sub 6}]{sup 4-} framework, which is constructed by the distorted tetrahedral CuQ{sub 4} and pyramid SbQ{sub 3} units via vertex sharing. Both optical properties and theoretical studies show 1 and 2 are semiconductors with narrow band gaps. In addition, their photoelectrochemical properties have been investigated. - Highlights: • BaCuSbQ{sub 3} (Q = S, Se) were synthesized through a hydrazine-hydrothermal method. • BaCuSbQ{sub 3} (Q = S, Se) feature a 3D framework by single-crystal X-ray diffraction. • Experimental and theoretical studies confirm BaCuSbQ{sub 3} (Q = S, Se) are semiconductors. • Photoelectrochemical properties of BaCuSbQ{sub 3} (Q = S, Se) have been investigated.

  4. Nebulization during spontaneous breathing, CPAP, and bi-level positive-pressure ventilation: a randomized analysis of pulmonary radioaerosol deposition.

    Science.gov (United States)

    Maccari, Juçara Gasparetto; Teixeira, Cassiano; Savi, Augusto; de Oliveira, Roselaine Pinheiro; Machado, André Sant'ana; Tonietto, Tulio Frederico; Ludwig, Eduardo; Teixeira, Paulo José Zimermann; Knorst, Marli Maria

    2014-04-01

    There have been few reports of factors affecting aerosol delivery during noninvasive ventilation (NIV). Nebulization is a standard practice, and our objective was to determine the effect of spontaneous breathing (SB) and NIV mode on lung technetium-99m ((99m)Tc) deposition in subjects with normal lungs. Thirteen health care volunteers were submitted to a randomized radioaerosol nebulization with (99m)Tc during SB, CPAP (10 cm H2O), and bi-level positive-pressure ventilation (bi-level; inspiratory-expiratory pressures of 15/5 cm H2O). NIV was performed via a ventilator (VPAP II ST-A, ResMed, Sydney, Australia). The radioaerosol deposition was evaluated by pulmonary scintigraphy after 10 min of inhalation. Regions of interest (ROIs) were outlined on the left lung (LL), right lung (RL), and trachea (TRQ). The average number of counts/pixel in each ROI was determined, and the ratio of lung and trachea was calculated. The three techniques showed comparable lung deposition. Analysis of radioaerosol deposition in the lungs showed a mean count at RL of 108.7 ± 40 with CPAP, 111.5 ± 15 with bi-level, and 196.6 ± 167 with SB. At LL, the values were 92.7 ± 15 with CPAP, 98.4 ± 14 with bi-level, and 225.0 ± 293 with SB. There was no difference between the means of radioaerosol deposition in RL, LL, or TRQ, as well as the lung calculated ratio (LCR = [RL + LL]/TRQ), which was similar in comparing ventilatory strategies. Based on our data, there is an equivalent deposition of inhaled substances in individuals with healthy lungs when SB, CPAP, and bi-level are compared.

  5. Phase transition in SbCl 5 - graphite studied by spin resonance experiments

    Science.gov (United States)

    Rolla, S.; Walmsley, L.; Suematsu, H.; Torriani, I.; Rettori, C.; Yosida, Y.

    1986-05-01

    Conduction Carrier Spin Resonance (CCSR) experiments in stage 3 and 4 acceptor SbCl 5 - Graphite Intercalated Compounds (GICs) reveal an almost stage independent phase transition at T c ≋ 225K. The CCSR linewidth shows an anomalous broadening below T c, which is observable only when the sample is kept in a region close to T c (190-225K); the broadening was not observed for rapid cooling. This broadening has a much faster kinetics for heating than for cooling rum. These thermal hysteresis and kinetics are quite similar to those found in AlCl 3-GICs. We attribute this phase transition to the quasi-2D "solid liquid" transformation experienced by the minority molecules of SbCl 3 present among the intercalated species in SbCl 5-GICs, proposed by Homma and Clarke. For stage 2 data does not show evidences of this phase transition.

  6. Alternative synthetic route for the heterometallic CO-releasing [Sb@Rh12(CO27]3− icosahedral carbonyl cluster and synthesis of its new unsaturated [Sb@Rh12(CO24]4− and dimeric [{Sb@Rh12Sb(CO25}2Rh(CO2PPh3]7− derivatives

    Directory of Open Access Journals (Sweden)

    Cristina Femoni

    2016-10-01

    Full Text Available The hetero-metallic [Sb@Rh12(CO27]3− cluster has been known as for over three decades thanks to Vidal and co-workers, and represents the first example of an E-centered (E=heteroatom icosahedral rhodium carbonyl cluster. However, its synthesis required high temperature (140–160 °C and elevated CO pressure (400 atm. Applying the redox condensation method for cluster preparation, we herein report a new synthetic, high-yield route for preparing [Sb@Rh12(CO27]3− under much milder conditions of temperature and pressure. Notably, when the same synthesis was carried out under N2 instead of CO atmosphere, the new isostructural but unsaturated derivative [Sb@Rh12(CO24]4− was obtained, for which we report the full X-ray structural characterization. This species represents one of the few examples of an icosahedral cluster disobeying the electron-counting Wade-Mingos rules, possessing less than the expected 170 cluster valence electrons (CVEs. Judging from IR monitoring, the two species can be obtained one from the other by switching between N2 and CO atmosphere, making [Sb@Rh12(CO27]3− a spontaneous CO-releasing molecule. Finally, the study of the chemical reactivity of [Sb@Rh12(CO27]3− with PPh3 allowed us to obtain the new [{Sb@Rh12Sb(CO25}2Rh(CO2PPh3]7− dimeric compound, for which we herein report the full X-ray structural and 31P NMR analyses.

  7. Structural, chemical, and thermoelectric properties of Bi{sub 2}Te{sub 3} Peltier materials. Bulk, thin films, and superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Peranio, Nicola

    2008-07-01

    In this work, the nature of the natural nanostructure (nns) was analysed and the correlations to the transport coefficients, particularly the lattice thermal conductivity, is discussed. Experimental methods are presented for the first time, yielding an accurate quantitative analysis of the chemical composition and of stress fields in Bi{sub 2}Te{sub 3} and in compounds with similar structural and chemical microstructures. This work can be subdivided as follows: (I) N-type Bi{sub 2}(Te{sub 0.91}Se{sub 0.09}){sub 3} and p-type (Bi{sub 0.26}Sb{sub 0.74}){sub 1.98}(Te{sub 0.99}Se{sub 0.01}){sub 3.02} bulk materials synthesised by the Bridgman technique. (II) Bi{sub 2}Te{sub 3} thin films and Bi{sub 2}Te{sub 3}/Bi{sub 2}(Te{sub 0.88}Se{sub 0.12}){sub 3} superlattices epitaxially grown by molecular beam epitaxy (MBE) on BaF{sub 2} substrates with periods of {delta}-12 nm at the Fraunhofer-Institut fuer Physikalische Messtechnik (IPM). (III) Experimental methods, i.e., TEM specimen preparation, high-accuracy quantitative chemical analysis by EDX in the TEM, and image simulations of dislocations and the nns according to the two-beam dynamical diffraction theory. The nns was analysed in detail by stereomicroscopy and by image simulation and was found to be a pure sinusoidal displacement field with (i) a displacement vector parallel to <5,-5,1> and an amplitude of about 10 pm and (ii) a wave vector parallel to {l_brace}1,0,10{r_brace} and a wavelength of 10 nm. The results obtained here showed a significant amount of stress in the samples, induced by the nns which was still not noticed and identified. Both kinds of nanostructures, artificial (ans) and natural (nns) nanostructures, yielded in thermoelectric materials a low lattice thermal conductivity which was beneficial for the thermoelectric figure of merit ZT. (orig.)

  8. Ternary and quaternary oxides of Bi, Sr and Cu

    Science.gov (United States)

    Casais, M. T.; Millan, P.; Rasines, I.; Campa, J. A.

    1991-01-01

    Before the discovery of superconductivity in an oxide of Bi, Sr, and Cu, the system Bi-Sr-Cu-O had not been studied, although several solid phases had been identified in the two-component regions of the ternary system Bi2O3-Si-O-CuO. The oxides Sr2CuO3, SrCu2O2, SrCuO2, and Bi2CuO4 were then well known and characterized, and the phase diagram of the binary system Bi2O3-SrO had been established in the temperature range 620 to 1000 C. Besides nine solutions of compositions Bi(2-2x) Sr(x) O(3-2x) and different symmetries, this diagram includes three definite compounds of stoichiometries Bi(2)BrO4. Bi2Sr2O5, and Bi2Sr3O6 (x - 0.50, 0.67 and 0.75 respectively), only the second of which with known unit-cell of orthorhombic symmetry, dimensions (A) a = 14.293(2), b = 7.651(2), c = 6.172(1), and z = 4. The first superconducting oxide in the system Bi-Sr-Cu-O was initially formulated as Bi2Sr2Cu2O(7+x), with an orthorhombic unit-cell of parameters (A) a = 5.32, b = 26.6, c = 48.8. In a preliminary study the same oxide was formulated with half the copper content, Bi(2)Sr(2)CuO(6+x), and index its reflections assuming an orthorhombic unit-cell of dimensions (A) a = 5.390(2), b = 26.973(8), c = 24.69(4). Subsequent studies by diffraction techniques have confirmed the composition 2:2:1. A new family of oxygen-deficient perovskites, was characterized, after identifying by x ray diffraction the phases present in the products of thermal treatments of about 150 mixtures of analytical grade Bi2O3, Sr(OH)2-8H2O and CuO at different molar ratios. X ray diffraction data are presented for some other oxides of Bi and Sr, as well as for various quaternary oxides, among them an oxide of Bi, Sr, and Cu.

  9. Single Crystal Growth and Superconducting Properties of Antimony-Substituted NdO0.7F0.3BiS2

    Directory of Open Access Journals (Sweden)

    Satoshi Demura

    2017-12-01

    Full Text Available Antimony (Sb substitution of less than 8% was examined on a single crystal of a layered superconductor NdO0.7F0.3BiS2. The superconducting transition temperature of the substituted samples decreased as Sb concentration increased. A lattice constant along the c-axis showed a large decrease compared with that along the a-axis. Since in-plane chemical pressure monotonically decreased as Sb concentration increased, the suppression of the superconductivity is attributed to the decrease in the in-plane chemical pressure.

  10. Diluted ferromagnetic semiconductor (LaCa)(ZnMn)SbO isostructural to ``1111'' type iron pnictide superconductors

    Science.gov (United States)

    Han, Wei; Zhao, Kan; Wang, XianCheng; Liu, QingQing; Ning, FanLong; Deng, Zheng; Liu, Ying; Zhu, JinLong; Ding, Cui; Man, HuiYuan; Jin, ChangQing

    2013-11-01

    We report discovery of ferromagnetism in (LaCa)(ZnMn)SbO isostructural to the well-studied iron-based superconductor LaFeAs(O1- x F x ). Spin is induced by partial substitution of Mn2+ for Zn2+, while charge is induced by substitution of Ca2+ for La3+ within the parent compound LaZnSbO. Ferromagnetism with Curie temperature ( T C) is observed up to 40 K at the spin doping 0.15 by introducing Mn2+ into the Zn2+ sites for (La0.95Ca0.05)(Zn1- x Mn x )SbO. The Hall coefficient measurement indicates p-type carrier for (La0.95Ca0.05)(Zn0.9Mn0.1)SbO with concentration of n˜1020 cm-3 showing anomalous Hall effect below T C.

  11. Room-Temperature Indentation Creep and the Mechanical Properties of Rapidly Solidified Sn-Sb-Pb-Cu Alloys

    Science.gov (United States)

    Kamal, Mustafa; El-Bediwi, A.; Lashin, A. R.; El-Zarka, A. H.

    2016-05-01

    In this paper, we study the room-temperature indentation creep and the mechanical properties of Sn-Sb-Pb-Cu alloys. Rapid solidification from melt using the melt-spinning technique is applied to prepare all the alloys. The experimental results show that the magnitude of the creep displacement increases with the increase in both time and applied load, and the stress exponent increases with the increase in the copper content in the alloys which happens primarily due to the existence of the intermetallic compounds SbSn and Cu6Sn5. The calculated values of the stress exponent are in the range of 2.82 to 5.16, which are in good agreement with the values reported for the Sn-Sb-Pb-Cu alloys. We have also studied and analyzed the structure, elastic modulus, and internal friction of the Sn-Sb-Pb-Cu alloys.

  12. The influence of replacing the pnicogens As by Sb on the optical properties of the Zintl phases Ba{sub 2}Cd{sub 2}Pn{sub 3} (Pn = As and Sb)

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H., E-mail: maalidph@yahoo.co.uk [New Technologies – Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia)

    2015-11-05

    We explored the influence of changing the pnicogens by substituting As by Sb on the optical properties of Ba{sub 2}Cd{sub 2}Pn{sub 3} (Pn = As and Sb). Calculation show that there exists subtle difference in the electronic structures when we substitute As by Sb, which lead to significant influence on the optical properties, taking into account the size and the electro-negativity differences between As and Sb atoms. The full potential method within the recently modified Becke-Johnson potential explore that the Ba{sub 2}Cd{sub 2}Pn{sub 3} (Pn = As and Sb) compounds are narrow band gap semiconductors of about 0.49 and 0.32 eV. The optical properties explore that these material have negative uniaxial anisotropy, negative birefringence and considerable anisotropy between the optical components in the polarization directions [100], [010] and [001] with respect to the crystal axis. Furthermore, the optical properties confirm that Ba{sub 2}Cd{sub 2}Sb{sub 3} possess a band gap which is smaller than that of Ba{sub 2}Cd{sub 2}As{sub 3}. The optical properties helps to get deep insight into the electronic structure. - Highlights: • The optical properties of Ba{sub 2}Cd{sub 2}Pn{sub 3} (Pn = As and Sb) were investigated. • The subtle difference in electronic structures influence the optical properties. • Ba{sub 2}Cd{sub 2}Pn{sub 3} (Pn = As and Sb) are narrow band gap semiconductors. • The investigated compounds exhibit negative uniaxial anisotropy and birefringence.

  13. The single crystal structure determination of Ln{sub 6}MnSb{sub 15} (Ln=La, Ce), Ln{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), and Ln{sub 6}ZnSb{sub 15} (Ln=La-Pr)

    Energy Technology Data Exchange (ETDEWEB)

    Benavides, Katherine A.; McCandless, Gregory T.; Chan, Julia Y. [Texas Univ., Dallas, Richardson, TX (United States). Dept. of Chemistry and Biochemistry

    2017-09-01

    Single crystals of Ln{sub 6}MnSb{sub 15} (Ln=La, Ce), Ln{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), and Ln{sub 6}ZnSb{sub 15} (Ln=La-Pr) have been successfully grown and the compounds adopt the orthorhombic Ln{sub 6}MnSb{sub 15} structure type (space group Immm), with a∝4.3 Aa, b∝15 Aa, and c∝19 Aa. This structure is comprised of antimony nets and antimony ribbons which exhibit positional disorder at connecting points between antimony substructures, in addition to two partially occupied transition metal sites. The unit cell volumes of the La analogs displayed a systematic decrease upon Zn substitution. However, for the Ce{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} and Pr{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), the volumes deviate from linearity as observed in the parent compounds.

  14. On atomic mechanisms governing the oxidation of Bi2Te3

    Science.gov (United States)

    Music, Denis; Chang, Keke; Schmidt, Paul; Braun, Felix N.; Heller, Martin; Hermsen, Steffen; Pöllmann, Peter J.; Schulzendorff, Till; Wagner, Cedric

    2017-12-01

    Oxidation of Bi2Te3 (space group R \\overline{3} m) has been investigated using experimental and theoretical means. Based on calorimetry, x-ray photoelectron spectroscopy and thermodynamic modelling, Bi2Te3 is at equilibrium with Bi2O3 and TeO2, whereby the most stable compound is Bi2Te3, followed by Bi2O3. The reactivity of Bi towards oxygen is expected to be higher than that of Te. This notion is supported by density functional theory. The strongest bond is formed between Bi and Te, followed by Bi–O. This gives rise to unanticipated atomic processes. Dissociatively adsorbed oxygen diffuses through Bi and Te basal planes of Bi2Te3(0 0 0 1) and preferably interacts with Bi. The Te termination considerably retards this process. These findings may clarify conflicting literature data. Any basal plane off-cut or Bi terminations trigger oxidation, but a perfect basal cleavage, where only Te terminations are exposed to air, may be stable for a longer period of time. These results are of relevance for applications in which surfaces are of key importance, such as nanostructured Bi2Te3 thermoelectric devices.

  15. Multiferroic Compounds with Double-Perovskite Structures

    Directory of Open Access Journals (Sweden)

    Noriya Ichikawa

    2011-01-01

    Full Text Available New multiferroic compounds with double-perovskite structures were synthesized. Bi2NiMnO6 was synthesized in bulk form by high-pressure synthesis and also in a thin-film form by epitaxial growth. The material showed both ferromagnetic and ferroelectric properties, i.e., the multiferroic property at low temperature. Bi2FeCrO6 was also fabricated in a (1 1 1 oriented BiFeO3/BiCrO3 artificial superlattice, with a 1/1 stacking period. The superlattice film showed ferromagnetic behavior and polarization switching at room temperature. In the compounds, Bi3+ ion, located at the A site in the perovskite structure, caused ferroelectric structural distortion, and the B-site ordering of the Ni2+ and Mn4+ ions (Fe3+ and Cr3+ ions in a rock-salt configuration led to ferromagnetism according to the Kanamori-Goodenough rule.

  16. Ambipolar field effect in the ternary topological insulator (BixSb1–x)2Te3 by composition tuning

    KAUST Repository

    Kong, Desheng

    2011-10-02

    Topological insulators exhibit a bulk energy gap and spin-polarized surface states that lead to unique electronic properties 1-9, with potential applications in spintronics and quantum information processing. However, transport measurements have typically been dominated by residual bulk charge carriers originating from crystal defects or environmental doping 10-12, and these mask the contribution of surface carriers to charge transport in these materials. Controlling bulk carriers in current topological insulator materials, such as the binary sesquichalcogenides Bi 2Te 3, Sb 2Te 3 and Bi 2Se 3, has been explored extensively by means of material doping 8,9,11 and electrical gating 13-16, but limited progress has been made to achieve nanostructures with low bulk conductivity for electronic device applications. Here we demonstrate that the ternary sesquichalcogenide (Bi xSb 1-x) 2Te 3 is a tunable topological insulator system. By tuning the ratio of bismuth to antimony, we are able to reduce the bulk carrier density by over two orders of magnitude, while maintaining the topological insulator properties. As a result, we observe a clear ambipolar gating effect in (Bi xSb 1-x) 2Te 3 nanoplate field-effect transistor devices, similar to that observed in graphene field-effect transistor devices 17. The manipulation of carrier type and density in topological insulator nanostructures demonstrated here paves the way for the implementation of topological insulators in nanoelectronics and spintronics. © 2011 Macmillan Publishers Limited. All rights reserved.

  17. InSb semiconductors and (In,Mn)Sb diluted magnetic semiconductors. Growth and properties

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Lien

    2011-04-13

    This dissertation describes investigations of the growth by molecular beam epitaxy and the characterization of the semiconductor InSb as well as the diluted magnetic semiconductor (DMS) In{sub 1-x}Mn{sub x}Sb. The InSb films were grown on GaAs (001) substrate and Si (001) offcut by 4 toward (110) substrate up to a thickness of about 2 {mu}m, in spite of a large lattice mismatch between the epi-layer and substrate (14.6% between InSb and GaAs, and 19.3% between InSb and Si). After optimizing the growth conditions, the best InSb films grown directly on GaAs without any special technique results in a high crystal quality, low noise, and an electron mobility of 41100 cm{sup 2}/V s Vs with associated electron concentration of 2.9.10{sup 6} cm{sup -3} at 300 K. Such structures could be used, for example, for infrared detector structures. The growth of InSb on Si, however, is a challenge. In order to successfully grow InSb on Si, tilted substrates and the insertion of buffer layers were used, which helps to reduce the lattice mismatch as well as the formation of defects, and hence to improve the crystal quality. An electron mobility of 24000 cm{sup 2}/V s measured at 300 K, with an associated carrier concentration of 2.6.10{sup 1}6 cm{sup -3} is found for the best sample that was grown at 340 C with a 0.06 {mu}m-thick GaSb/AlSb superlattice buffer layer. The smaller value of electron mobility (compared to the best GaAsbased sample) is related to a higher density of microtwins and stacking faults as well as threading dislocations in the near-interface region as shown by transmission electron microscopy. Deep level noise spectra indicate the existence of deep levels in both GaAs and Si-based samples. The samples grown on Si exhibit the lowest Hooge factor at 300 K, lower than the samples grown on GaAs. Taking the optimized growth conditions of InSb/GaAs, the diluted magnetic semiconductor In{sub 1-x}Mn{sub x}Sb/GaAs (001) is prepared by adding a few percent of Mn into the

  18. Polarity-dependent resistance switching in GeSbTe phase-change thin films : The importance of excess Sb in filament formation

    NARCIS (Netherlands)

    Pandian, Ramanathaswamy; Kooi, Bart J.; Oosthoek, Jasper L. M.; van den Dool, Pim; Palasantzas, George; Pauza, Andrew

    2009-01-01

    We show that polarity-dependent resistance switching in GeSbTe thin films depends strongly on Sb composition by comparing current-voltage characteristics in Sb-excess Ge(2)Sb(2+x)Te(5) and stoichiometric Ge(2)Sb(2)Te(5) samples. This type of switching in Ge(2)Sb(2+x)Te(5) films is reversible with

  19. Electrostatic performance of InSb, GaSb, Si and Ge p-channel nanowires

    Science.gov (United States)

    Martinez-Blanque, C.; Marin, E. G.; Toral, A.; Gonzalez-Medina, J. M.; Ruiz, F. G.; Godoy, A.; Gámiz, F.

    2017-12-01

    The electrostatic performance of p-type nanowires (NWs) made of InSb and GaSb, with special focus on their gate capacitance behaviour, is analysed and compared to that achieved by traditional semiconductors usually employed for p-MOS such as Si and Ge. To do so, a self-consistent \

  20. Synthesis and Characterization of Sn2+- based and Bi3+- based metal oxides for photocatalytic applications

    KAUST Repository

    Noureldine, Dalal

    2016-07-01

    The main challenge of water splitting technology is to develop stable, visible responsive photocatalysts that satisfy the thermodynamic requirements to achieve water redox reactions. This study investigates development of the semiconductors containing metals with s2d10 electronic configuration such as Sn2+ or Bi3+ which shifts the valence band position negatively. Efficient water splitting can, however, be only achieved by understanding the fundamental semiconductor properties of underlying processes. This work elucidates the semiconductor properties through two approaches: the first is to synthesize the materials of various stoichiometry in various forms (powders, thin film etc.) and the second is to perform a combined experimental-theoretical studies to determine the optoelectronic properties of the synthesized materials. The study includes the synthesis and characterization of a series of Bi3+ based semiconductors (Bi2Ti2O7, Bi12TiO20, and Bi4Ti3O12) to resolve inconsistencies in their optoelectronic properties. The crystal parameters and stoichiometry were confirmed by the Rietveld refinement and XRD measurements. These compounds showed a UV responsive absorption, high dielectric constants, and low electron and hole effective masses in one crystallographic reflecting their good charge separation and carrier diffusion properties. The approach showed to be accurate in determining the optoelectronic properties due to good agreement between experimental and theoretical values. The second study investigated the synthesis of SnNb2O6 and using flux assisted method which afforded control over the surface. Increasing the flux to reactant molar ratio resulted in a 2D platelets with anisotropic growth along bc plane as confirmed by XRD and SEM. The photocatalytic activity increased while increasing the flux to reactant ratio exceeding solid state synthesis. This method minimized the oxidation of the surface and formation of grain boundaries and enabled the synthesis of

  1. Few-Layer Nanoplates of Bi 2 Se 3 and Bi 2 Te 3 with Highly Tunable Chemical Potential

    KAUST Repository

    Kong, Desheng

    2010-06-09

    A topological insulator (TI) represents an unconventional quantum phase of matter with insulating bulk band gap and metallic surface states. Recent theoretical calculations and photoemission spectroscopy measurements show that group V-VI materials Bi2Se3, Bi2Te3, and Sb2Te3 are TIs with a single Dirac cone on the surface. These materials have anisotropic, layered structures, in which five atomic layers are covalently bonded to form a quintuple layer, and quintuple layers interact weakly through van der Waals interaction to form the crystal. A few quintuple layers of these materials are predicted to exhibit interesting surface properties. Different from our previous nanoribbon study, here we report the synthesis and characterizations of ultrathin Bi2Te3 and Bi2Se3 nanoplates with thickness down to 3 nm (3 quintuple layers), via catalyst-free vapor-solid (VS) growth mechanism. Optical images reveal thickness-dependent color and contrast for nanoplates grown on oxidized silicon (300 nm SiO2/Si). As a new member of TI nanomaterials, ultrathin TI nanoplates have an extremely large surface-to-volume ratio and can be electrically gated more effectively than the bulk form, potentially enhancing surface state effects in transport measurements. Low-temperature transport measurements of a single nanoplate device, with a high-k dielectric top gate, show decrease in carrier concentration by several times and large tuning of chemical potential. © 2010 American Chemical Society.

  2. Shape and size control of InAs/InP (113)B quantum dots by Sb deposition during the capping procedure.

    Science.gov (United States)

    Lu, W; Bozkurt, M; Keizer, J G; Rohel, T; Folliot, H; Bertru, N; Koenraad, P M

    2011-02-04

    The role of Sb atoms present on the growth front during capping of InAs/InP (113)B quantum dots (QDs) is investigated by cross-sectional scanning tunnelling microscopy, atomic force microscopy, and photoluminescence spectroscopy. Direct capping of InAs QDs by InP results in partial disassembly of InAs QDs due to the As/P exchange occurring at the surface. However, when Sb atoms are supplied to the growth surface before InP capping layer overgrowth, the QDs preserve their uncapped shape, indicating that QD decomposition is suppressed. When GaAs(0.51)Sb(0.49) layers are deposited on the QDs, conformal growth is observed, despite the strain inhomogeneity existing at the growth front. This indicates that kinetics rather than the strain plays the major role during QD capping with Sb compounds. Thus Sb opens up a new way to control the shape of InAs QDs.

  3. Study of vortex dynamics with local magnetic relaxation measurements in the superconducting compound Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}; Etude de la dynamique des vortex par des mesures locales de relaxation magnetique dans le compose supraconducteur Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Berry, St

    2000-07-01

    This experimental study of the magnetic field-temperature phase diagram and of the vortex dynamics in high- T{sub c} superconductors focuses on Bismuth-based cuprates: Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}. In type-II superconductors, mixed state characterized by the presence of vortices (quanta of magnetic flux) is divided by a transition line determined by two features of magnetization loops. For T > 40 K, magnetization loops vs applied field show a step evidence of a first order transition. From 20 to 40 K, a second peak replacing the step correspond to an abrupt increase of irreversibility interpreted as a bulk current. We want to understand the nature of the second peak (thermodynamic or nonequilibrium property) and separate phenomena contributing to irreversibility (flux pinning, geometrical or surface effects). Magnetic measurement techniques are nondestructive and have a resolution of few microns. Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} single crystals are optimized by localizing defectives regions with a magneto-optic technique for flux imaging and elimination of these regions with a wire saw. Local magnetization loops and relaxation measurements performed with a microscopic Hall probe array allow to distinguish irreversibility sources. The shape of induction profiles indicates which current dominate between surface current and bulk pinning induced current. Two crossover with time and a direct observation of two phases coexistence in induction profiles enlighten phenomena in play. The measured electric field-current density characteristics lead to barrier energy U(j) controlling thermally activated flux motion. Three relations (U(j) (surface, bulk low and high field) explain second peak. (author)

  4. DWPF simulant CPC studies for SB8

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D. C.; Zamecnik, J. R.

    2013-06-25

    The Savannah River National Laboratory (SRNL) accepted a technical task request (TTR) from Waste Solidification Engineering to perform simulant tests to support the qualification of Sludge Batch 8 (SB8) and to develop the flowsheet for SB8 in the Defense Waste Processing Facility (DWPF). These efforts pertained to the DWPF Chemical Process Cell (CPC). Separate studies were conducted for frit development and glass properties (including REDOX). The SRNL CPC effort had two primary phases divided by the decision to drop Tank 12 from the SB8 constituents. This report focuses on the second phase with SB8 compositions that do not contain the Tank 12 piece. A separate report will document the initial phase of SB8 testing that included Tank 12. The second phase of SB8 studies consisted of two sets of CPC studies. The first study involved CPC testing of an SB8 simulant for Tank 51 to support the CPC demonstration of the washed Tank 51 qualification sample in the SRNL Shielded Cells facility. SB8-Tank 51 was a high iron-low aluminum waste with fairly high mercury and moderate noble metal concentrations. Tank 51 was ultimately washed to about 1.5 M sodium which is the highest wash endpoint since SB3-Tank 51. This study included three simulations of the DWPF Sludge Receipt and Adjustment Tank (SRAT) cycle and Slurry Mix Evaporator (SME) cycle with the sludge-only flowsheet at nominal DWPF processing conditions and three different acid stoichiometries. These runs produced a set of recommendations that were used to guide the successful SRNL qualification SRAT/SME demonstration with actual Tank 51 washed waste. The second study involved five SRAT/SME runs with SB8-Tank 40 simulant. Four of the runs were designed to define the acid requirements for sludge-only processing in DWPF with respect to nitrite destruction and hydrogen generation. The fifth run was an intermediate acid stoichiometry demonstration of the coupled flowsheet for SB8. These runs produced a set of processing

  5. Thin films in ternary Bi-Mn-O system obtained by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Langenberg, E. [Departament de Fisica Aplicada i Optica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Catalunya (Spain)], E-mail: eric.langenberg@ub.edu; Varela, M.; Garcia-Cuenca, M.V.; Ferrater, C. [Departament de Fisica Aplicada i Optica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Catalunya (Spain); Sanchez, F.; Fontcuberta, J. [Institut de Ciencia de Materials de Barcelona, CSIC, Campus de la UAB, 08193 Bellaterra, Catalunya (Spain)

    2007-11-25

    We have explored the influence of deposition temperature and the deposition rate on the growth of the ternary Bi-Mn-O system onto (0 0 1) SrTiO{sub 3} substrates by pulsed laser deposition. The studies were performed with a fixed oxygen pressure of 10 Pa (0.1 mbar) and substrate temperatures between 600 and 680 deg. C. The films were obtained from non-stoichiometric targets with 10 and 15% Bi excess in order to compensate for Bi volatility. The fact that the compound is metastable together with the high volatility of Bi induces different Bi and Mn oxides apart from BiMnO{sub 3}. Stabilisation of epitaxial BiMnO{sub 3} is therefore very elusive and only in a narrow temperature window around 630 deg. C the presence of spurious phases is reduced to traces. X-ray diffraction results reveal a correlation between the Bi-Mn-O compounds and the deposition temperature. Reciprocal space maps show that the BiMnO{sub 3} grows completely strained on SrTiO{sub 3} substrates. The unit cell has a reduced volume, which could be due to the presence of Bi vacancies. The surface of the films is rough, but they flatten when the films are obtained at lower deposition rates.

  6. bi tule

    Index Scriptorium Estoniae

    2004-01-01

    8.-18. IV 2004 Eesti Tarbekunsti- ja Disainimuuseumis Eesti Kunstiakadeemia keraamikaosakonna magistrantide grupinäitus "Läbi tule". Reeli Haamer, Kadri Kivi, Annika Vilippus, Ingrid Allik, Mathew Graziano ja Milvi Korela kaitsevad 12. IV oma magistritööd. 23. IV-15. VI näitus Leesi Ermi loomingust sarjas "Klassikud"

  7. Photocharged BiVO

    NARCIS (Netherlands)

    Trzesniewski, B.J.; Smith, W.A.

    2016-01-01

    Bismuth vanadate (BiVO4) is a promising semiconductor material for the production of solar fuels via photoelectrochemical water splitting, however, it suffers from substantial recombination losses that limit its performance to well below its theoretical maximum. Here we demonstrate for the first

  8. Sonochemical preparation of SbSI gel.

    Science.gov (United States)

    Nowak, M; Szperlich, P; Bober, L; Szala, J; Moskal, G; Stróz, D

    2008-07-01

    A novel sonochemical method for direct preparation of nanocrystalline antimony sulfoiodide (SbSI) has been established. The SbSI gel was synthesized using elemental Sb, S and I in the presence of ethanol under ultrasonic irradiation (35 kHz, 2 W/cm2) at 50 degrees C for 2 h. The products were characterized by using techniques such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and optical diffuse reflection spectroscopy (DRS). The SEM and HRTEM investigations exhibit that the as-prepared samples are made up of large quantity nanowires with diameters of about 10-50 nm and lengths reaching up to several micrometers and single-crystalline in nature.

  9. Adsorption of Sb(III) and Sb(V) on Freshly Prepared Ferric Hydroxide (FeOxHy).

    Science.gov (United States)

    He, Zan; Liu, Ruiping; Liu, Huijuan; Qu, Jiuhui

    2015-02-01

    This study prepared fresh ferric hydroxide (in-situ FeOxHy) by the enhanced hydrolysis of Fe3+ ions, and investigates its adsorptive behaviors toward Sb(III) and Sb(V) through laboratory and pilot-scale studies. A contact time of 120-min was enough to achieve adsorption equilibrium for Sb(III) and Sb(V) on the in-situ FeOxHy, and the Elovich model was best to describe the adsorption kinetics of Sb(III) and Sb(V). The Freundlich model was better than Langmuir model to describe the adsorption of Sb(III) and Sb(V) on the in-situ FeOxHy, and the maximum adsorption capacity of Sb(III) and Sb(V) was determined to be 12.77 and 10.21 mmol/g the in-situ FeOxHy as Fe, respectively. Adsorption of Sb(V) decreased whereas that of Sb(III) increased with elevated pH over pH 3-10, owing to the different electrical properties of Sb(III) and Sb(V). Adsorption of Sb(III) and Sb(V) was slightly affected by ionic strength, and thus indicated the formation of inner sphere complexes between Sb and the adsorbent. Sulfate and carbonate showed little effect on the adsorption of Sb(III) and Sb(V). Phosphate significantly inhibited the adsorption of Sb(V), whereas slightly effected that of Sb(III) due to its similar chemical structure to Sb(V). Pilot-scale continuous experiment indicated the feasibility of using in-situ FeOxHy to remove Sb(V), and equilibrium adsorption capacity at the equilibrium Sb(V) concentration of 10 μg/L was determined to be 0.11, 0.07, 0.07, 0.11, and 0.12 mg/g the in-situ FeOxHy as Fe at equilibrium pH of 7.5-7.7, 6.9-7.0, 6.3-6.6, 5.9-6.4, and 5.2-5.9, respectively.

  10. Variation of properties of glasses along the 3Bi2O3 X 5B2O3-4PbO X B2O3 and PbO X 2B2O3-2PbO X Bi2O3 sections of the PbO-Bi2O3-B2O3 ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zargarova, M.I.; Shuster, N.S.

    1985-07-01

    Already published data on the phase diagrams of Pb-B2O3, Bi2O3-B2O3, and PbO-Bi2O3 systems serve as the basis of this investigation, together with original experiments on the PbO-Bi2O3-B2O3 ternary system. The authors establish the quasi binary nature of the 3Bi2O3 X 5B2O3 - 4PbO X B2O3 section with the formation of the congruently melting ternary compound 3Bi2O3 X 8PbO X 7B2O3, and they demonstrate the role of the ternary compound 3Bi2O3 X 8PbO X 7B2O3 as a glass former in the PbO-Bi2O3 - B2O3 system.

  11. Determining the effect of Ru substitution on the thermal stability of CeFe[subscript 4-x]Ru[subscript x]Sb[subscript 12

    Energy Technology Data Exchange (ETDEWEB)

    Sigrist, Jessica A.; Walker, James D.S.; Hayes, John R.; Gaultois, Michael W.; Grosvenor, Andrew P. (Saskatchewan)

    2011-11-14

    The ternary, rare-earth filled (RE) Skutterudites (REM{sub 4}Pn{sub 12}; M = Fe-Os; Pn = P-Sb) have been proposed for use in high-temperature thermoelectric devices to convert waste heat to useful power. CeFe{sub 4}Sb{sub 12} has been one of the most popular materials proposed for this application; however, it oxidizes at relatively low temperatures. The thermal stability of Skutterudites can be enhanced by selective substitution of the constituent elements and Eu(Fe,Ru){sub 4}Sb{sub 12} variants have been found to oxidize at temperatures above that of CeFe{sub 4}Sb{sub 12}. Unfortunately, these materials have poor thermoelectric properties. In this study, the thermal stability of CeFe{sub 4-x}Ru{sub x}Sb{sub 12} was examined depending on the value of x. (These compounds have similar thermoelectric properties to those of CeFe{sub 4}Sb{sub 12}.) It has been found by use of TGA and XANES that the temperature at which point CeFe{sub 4-x}Ru{sub x}Sb{sub 12} oxidizes increases with greater Ru substitution. XANES was also used to confirm the general charge assignment of Ce{sup 3+}Fe{sub 4-x}{sup 2+}Ru{sub x}{sup 2+}Sb{sub 12}{sup 1-}.

  12. Determining the effect of Ru substitution on the thermal stability of CeFe 4- xRu xSb 12

    Science.gov (United States)

    Sigrist, Jessica A.; Walker, James D. S.; Hayes, John R.; Gaultois, Michael W.; Grosvenor, Andrew P.

    2011-11-01

    The ternary, rare-earth filled (RE) Skutterudites (REM 4Pn12; M = Fe-Os; Pn = P-Sb) have been proposed for use in high-temperature thermoelectric devices to convert waste heat to useful power. CeFe 4Sb 12 has been one of the most popular materials proposed for this application; however, it oxidizes at relatively low temperatures. The thermal stability of Skutterudites can be enhanced by selective substitution of the constituent elements and Eu(Fe,Ru) 4Sb 12 variants have been found to oxidize at temperatures above that of CeFe 4Sb 12. Unfortunately, these materials have poor thermoelectric properties. In this study, the thermal stability of CeFe 4- xRu xSb 12 was examined depending on the value of x. (These compounds have similar thermoelectric properties to those of CeFe 4Sb 12.) It has been found by use of TGA and XANES that the temperature at which point CeFe 4- xRu xSb 12 oxidizes increases with greater Ru substitution. XANES was also used to confirm the general charge assignment of Ce 3+Fe 4- x2+Ru x2+Sb 121-.

  13. Lithium diffusion in a new cathode material Li0.8[Ni0.6Sb0.4]O2 studied by 7Li NMR

    Directory of Open Access Journals (Sweden)

    Salikhov T., Klysheva E., Zvereva E., Nalbandyan V., Shukaev I., Medvedev B., Vavilova E.

    2016-12-01

    Full Text Available A rhombohedral layered α-NaFeO2-type compound, Lix[Ni(1+x/3Sb(2-x/3]O2 (x=0.8 has been prepared from the sodium analogue by ion exchange at 570 K. In contrast to the stoichiometric composition Li3Ni2SbO6, it shows considerable Li/Ni inversion and no long-range Ni/Sb ordering. The temperature dependence of the 7Li NMR spin-lattice relaxation rate and linewidth data measured at temperature range from 30-450 K show the sharp increase of lithium ions mobility comparing to the stoichiometric compound Li3Ni2SbO6. From the NMR data the activation energy was estimated by different methods.

  14. GaAs/GaSb nanowire heterostructures grown by MOVPE

    DEFF Research Database (Denmark)

    Jeppsson, Mattias; Dick, Kimberly A.; Wagner, Jakob Birkedal

    2008-01-01

    to most other III–V nanowire systems, the GaSb nanowire growth is Group V-limited under most conditions. We found that depending on the TMSb molar fraction, the seed particle is either supersaturated AuGa or AuGa2 during GaSb growth. The high Ga content in the particle gives a characteristic diameter...... increase between the GaAs and GaSb segment. From TEM and XEDS measurements we conclude that the GaSb nanowire growth occurs along either the AuGa–GaSb or AuGa2–GaSb pseudo-binaries of the Au–Ga–Sb ternary phase diagram. Finally, the GaSb nanowires exhibit untapered radial growth on the {1 1¯ 0} side facets....

  15. Synthesis, impedance and dielectric properties of LaBi5Fe2Ti3O18

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The compound, LaBi5Fe2Ti3O18, is a five-layered material belonging to the family of bismuth .... compound. The maximum intensity was observed at ~ 30o of 2θ value, corresponding to (1, 1, 11) reflection, which was also observed in the parent compound. ... lated from the area under the curve (figure 7) is plotted.

  16. Electronic structure and physical properties of Heusler compounds for thermoelectric and spintronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Ouardi, Siham

    2012-03-19

    This thesis focuses on synthesis as well as investigations of the electronic structure and properties of Heusler compounds for spintronic and thermoelectric applications. The first part reports on the electronic and crystal structure as well as the mechanical, magnetic, and transport properties of the polycrystalline Heusler compound Co{sub 2}MnGe. The crystalline structure was examined in detail by extended X-ray absorption fine structure spectroscopy and anomalous X-ray diffraction. The low-temperature magnetic moment agrees well with the Slater-Pauling rule and indicates a half-metallic ferromagnetic state of the compound, as is predicted by ab-initio calculations. Transport measurements and hard X-ray photoelectron spectroscopy (HAXPES) were performed to explain the electronic structure of the compound. A major part of the thesis deals with a systematical investigation of Heusler compounds for thermoelectric applications. This thesis focuses on the search for new p-type Heusler compounds with high thermoelectric efficiency. The substitutional series NiTi{sub 1-x}M{sub x}Sn (where M=Sc, V and 0compound. The pure compounds showed n-type behavior, while under Sc substitution the system switched to p-type behavior. A maximum Seebeck coefficient of +230 {mu}V/K (350 K) was obtained for NiTi{sub 0.26}Sc{sub 0.04}Zr{sub 0.35}Hf{sub 0.35}Sn. HAXPES valence band measurement show massive in gap states for the parent compounds NiTiSn, CoTiSb and NiTi{sub 0.3}Zr{sub 0.35}Hf{sub 0.35}Sn. This proves that the electronic states close to the Fermi energy play a key role for the behavior of the transport properties. Furthermore, the electronic structure of the gapless Heusler compounds PtYSb, PtLaBi and PtLuSb were investigated by bulk

  17. Codoping of Sb2Te3 thin films with V and Cr

    Science.gov (United States)

    Duffy, L. B.; Figueroa, A. I.; van der Laan, G.; Hesjedal, T.

    2017-11-01

    Magnetically doped topological insulators (TIs) are key to realizing the quantum anomalous Hall (QAH) effect, with the prospect of enabling dissipationless electronic devices in the future. Doping of the well-established three-dimensional TIs of the (Bi,Sb) 2(Se,Te) 3 family with the transition metals Cr and V is now an established approach for observing the QAH state at very low temperatures. While the magnetic transition temperatures of these materials are on the order of tens of degrees Kelvin, full quantization of the QAH state is achieved below ˜100 mK, governed by the size of the magnetic gap and thus the out-of-plane magnetic moment. In an attempt to raise the size of the magnetic moment and transition temperature, we carried out a structural and magnetic investigation of codoped (V,Cr):Sb2Te3 thin films. Starting from singly doped Cr:Sb2Te3 films, free of secondary phases and with a transition temperature of ˜72 K, we introduced increasing fractions of V and found a doubling of the transition temperature, while the magnetic moment decreases. In order to separate the properties and contributions of the two transition metals in the complex doping scenario independently, we employed spectroscopic x-ray techniques. Surprisingly, already small amounts of V lead to the formation of the secondary phase Cr2Te3 . No V was detectable in the Sb2Te3 matrix. Instead, it acts as a surfactant and can be found in the near-surface layers at the end of the growth. Our paper highlights the importance of x-ray-based studies for the doping of van der Waals systems, for which the optimization of magnetic moment or transition temperature alone is not necessarily a good strategy.

  18. Sulfuric Acid Corrosion of Low Sb - Pb Battery Alloys | Ntukogu ...

    African Journals Online (AJOL)

    The corrosion properties of low Sb - Pb alloys developed for maintenance free motive power industrial batteries was studied by a bare grid constant current method and compared to those of the conventional Pb- 6% Sb alloy. Low Sb-Pb alloys with Se and As grain refiners were found to have higher corrosion rates than the ...

  19. Structure and properties of (1− x)[(K0. 5Na0. 5) NbO3–LiSbO3 ...

    Indian Academy of Sciences (India)

    Lead-free piezoelectric ceramics ( 1 − x ) [0.95(K 0.5 Na 0.5 )NbO 3 –0.05LiSbO 3 ]– x BiFe 0.8 Co 0.2 O 3 (KNN–LS– x BFC) were prepared by a conventional sintering technique. The effect of BFC content on the structure, piezoelectricand electrical properties of KNN–LS ceramics was investigated. The results reveal that ...

  20. High current density Esaki tunnel diodes based on GaSb-InAsSb heterostructure nanowires.

    Science.gov (United States)

    Ganjipour, Bahram; Dey, Anil W; Borg, B Mattias; Ek, Martin; Pistol, Mats-Erik; Dick, Kimberly A; Wernersson, Lars-Erik; Thelander, Claes

    2011-10-12

    We present electrical characterization of broken gap GaSb-InAsSb nanowire heterojunctions. Esaki diode characteristics with maximum reverse current of 1750 kA/cm(2) at 0.50 V, maximum peak current of 67 kA/cm(2) at 0.11 V, and peak-to-valley ratio (PVR) of 2.1 are obtained at room temperature. The reverse current density is comparable to that of state-of-the-art tunnel diodes based on heavily doped p-n junctions. However, the GaSb-InAsSb diodes investigated in this work do not rely on heavy doping, which permits studies of transport mechanisms in simple transistor structures processed with high-κ gate dielectrics and top-gates. Such processing results in devices with improved PVR (3.5) and stability of the electrical properties.

  1. First-principles study lone-pair effects of Sb (III)-S chromophore influence on SHG response in quaternary potassium containing silver antimony sulfides

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Junben [Key Laboratory of Functional Materials and Devices for Special Environments of CAS,, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, 40-1 South Beijing Road, Urumqi 830011 (China); School of Physics Science and Technology, Xinjiang University, Urumqi 830046 (China); Su, Xin; Hou, Dianwei; Lei, Binghua [Key Laboratory of Functional Materials and Devices for Special Environments of CAS,, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, 40-1 South Beijing Road, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yang, Zhihua, E-mail: zhyang@ms.xjb.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS,, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, 40-1 South Beijing Road, Urumqi 830011 (China); Pan, Shilie, E-mail: slpan@ms.xjb.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS,, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, 40-1 South Beijing Road, Urumqi 830011 (China)

    2017-05-15

    First-principles studies of the geometric structures, electronic structures and optical properties of non-centrosymmetrical (NCS) KAg{sub 2}SbS{sub 4}, K{sub 2}AgSbS{sub 4} and K{sub 2}Ag{sub 3}Sb{sub 3}S{sub 7} and centrosymmetrical (CS) KAg{sub 2}SbS{sub 3} and K{sub 3}Ag{sub 9}Sb{sub 4}S{sub 12} have been performed by means of density functional theory. It is indicated that although they have similarity in their anionic groups and, the electronic structures, prominent features of the optical anisotropy or second-order nonlinear optical (NLO) susceptibilities are apparently different. The calculated birefringences are 0.0537, 0.0343, 0.1324, 0.2217 and 0.0604 which are attributed to the different anionic groups [SbS{sub 3}] and triangles [AgS{sub 3}]. Also, the calculated NLO responses are about 0.5×, 1.0× and 2.0× times than that commercial AgGaS{sub 2} (AGS, d{sub 36}=11 pm/V) for K{sub 2}AgSbS{sub 4}, KAg{sub 2}SbS{sub 4} and K{sub 2}Ag{sub 3}Sb{sub 3}S{sub 7}, respectively. In comparison with the absolute magnitude of second harmonic generation (SHG) coefficients, the order K{sub 2}Ag{sub 3}Sb{sub 3}S{sub 7}>KAg{sub 2}SbS{sub 4}>K{sub 2}AgSbS{sub 4} is clearly established in the SHG response. Further analysis based on the real-space atom-cutting method reveals that the main sources of the SHG properties of these compounds are from the Sb-S group, especially K{sub 2}Ag{sub 3}Sb{sub 3}S{sub 7} is mainly attributed to the lone pair stereochemical activity of Sb (III)-S group. - Graphical abstract: Compounds K{sub 2}AgSbS{sub 4}, KAg{sub 2}SbS{sub 4} and K{sub 2}Ag{sub 3}Sb{sub 3}S{sub 7} exhibit second-order NLO response: 15×, 30× and 62× times than that KDP (KH{sub 2}PO{sub 4}, d{sub 36}=0.39 pm/V), respectively. First-principles methods reveal that the large SHG response of K{sub 2}Ag{sub 3}Sb{sub 3}S{sub 7} is dominated by the Sb-S chromophore with lone pairs.

  2. Adsorption behavior and mechanism of ibuprofen onto BiOCl microspheres with exposed {001} facets.

    Science.gov (United States)

    Li, Jian; Sun, Shiye; Chen, Rong; Zhang, Tuqiao; Ren, Bangxing; Dionysiou, Dionysios D; Wu, Zhejian; Liu, Xiaowei; Ye, Miaomiao

    2017-04-01

    BiOCl microspheres with exposed {001} facets have been synthesized through a simple solvothermal method. The adsorption and photocatalytic activities of BiOCl microspheres were evaluated by removal of ibuprofen (IBP) as the model reaction. Parameters including IBP concentration, BiOCl dosage, and inorganic ions were investigated to reveal the role of adsorption in BiOCl-based photocatalysis. We found that the high IBP removal rate by BiOCl is not due to photocatalytic oxidation but to surface adsorption. The combination of ICP/MS, IC, XPS, and FT-IR results directly proved that anion exchange between dissociated IBP and Cl accompanied by the formation of surface complex (O-Bi-OOC-C 12 H 17 ) onto the BiOCl surface is the main adsorption mechanism. In addition, we also demonstrated that organic compounds with carboxyl group (-COOH) such as diclofenac, benzoic acid, and p-phthalic acid can be adsorbed by BiOCl while organic compounds without carboxyl group such as carbamazepine, nitrobenzene, and p-chloronitrobenzene cannot be adsorbed. We believe that the BiOCl adsorption behavior and mechanism should be considered when discussing its photocatalytic mechanism.

  3. The fire ant social chromosome supergene variant Sb shows low diversity but high divergence from SB

    OpenAIRE

    Pracana, Rodrigo; Priyam, Anurag; Levantis, Ilya; Nichols, Richard A.; Wurm, Yannick

    2017-01-01

    Abstract Variation in social behaviour is common, yet little is known about the genetic architectures underpinning its evolution. A rare exception is in the fire ant Solenopsis invicta: Alternative variants of a supergene region determine whether a colony will have exactly one or up to dozens of queens. The two variants of this region are carried by a pair of ?social chromosomes?, SB and Sb, which resemble a pair of sex chromosomes. Recombination is suppressed between the two chromosomes in t...

  4. The microstructure and properties of as-cast Sn-Zn-Bi solder alloys

    Directory of Open Access Journals (Sweden)

    Mladenović Srba A.

    2012-01-01

    Full Text Available Research on the lead-free solders has attracted wide attention, mostly as the result of the implementation of the Directive on the Restriction of the Use of Hazardous Substances in Electrical and Electronic Equipment. The Sn-Zn solder alloys have been considered to be one of the most attractive lead-free solders due to its ability to easily replace Sn-Pb eutectic alloy without increasing the soldering temperature. Furthermore, the mechanical properties are comparable or even superior to those of Sn-Pb solder. However, other problems still persist. The solution to overcoming these drawbacks is to add a small amount of alloying elements (Bi, Ag, Cr, Cu, and Sb to the Sn-Zn alloys. Microstructure, tensile strength, and hardness of the selected Sn-Zn-Bi ternary alloys have been investigated in this study. The SEM-EDS was used for the identification of co-existing phases in the samples. The specimens’ microstructures are composed of three phases: Sn-rich solid solution as the matrix, Bi-phase and Zn-rich phase. The Bi precipitates are formed around the Sn-dendrit grains as well as around the Zn-rich phase. The amount of Bi segregation increases with the increase of Bi content. The Sn-Zn-Bi alloys exhibit the high tensile strength and hardness, but the values of these mechanical properties decrease with the increase of Bi content, as well as the reduction of Zn content. The results presented in this paper may offer further knowledge of the effects various parameters have on the properties of lead-free Sn-Zn-Bi solders.

  5. Comportamiento eléctrico del compuesto Bi5FeTi3O15 y de sus soluciones sólidas con CaBi4Ti4O15

    Directory of Open Access Journals (Sweden)

    Durán, P.

    1999-12-01

    Full Text Available Bi5FeTi3O15 (BiFT compound has been prepared by solid state reaction between the corresponding oxides. Its crystalline structure has been established by X ray Diffraction, (XRD. Ceramic samples with apparent density > 95% Dth have been sintered. On these samples, electrical conductivity and Curie temperature have been measured. Solid solutions of Bi5FeTi3O15 (BiFT and CaBi4Ti4O15 (CBiT have been prepared. On poled samples of these solid solutions, piezoelectric parameters have been established. The BiFT compound shows electrical conductivity values very similar to those of the Bi4Ti3O12 (BiT compound. The electrical conductivity of solid solutions is a function of CBiT amount. A possible electrical conductivity mechanism which is different of that accepted for the BiT compound is discussed.Se ha preparado Bi5FeTi3O15 (BiFT por reacción en estado sólido de los óxidos correspondientes. Se ha determinado su estructura cristalina por Difracción de Rayos X (DRX. Se han preparado compactos sinterizados con densidades superiores al 95%. Se ha determinado su temperatura de Curie, y la conductividad eléctrica entre 150 y 850ºC. Se han preparado soluciones sólidas de Bi5FeTi3O15 con CaBi4Ti4O15, (CBiT y se han determinado los mismos parámetros de temperatura de Curie y de conductividad para ellas. En las soluciones sólidas se han determinado los parámetros Piezoeléctricos de muestras polarizadas Debe destacarse que el compuesto Bi5FeTi3O15 presenta unos valores de conducción eléctrica más próximos a los correspondientes al Bi4Ti3O12 (BiT que a los de los compuestos MeBi4Ti4O15. La conductividad eléctrica de las soluciones sólidas varía con el contenido de CBiT. Se discute la posible existencia de un modelo de conducción eléctrica que difiere del aceptado hasta el momento para el BiT, basado en los defectos localizados en las capas Bi2O2 2-.

  6. Ordering of La sup 3+ ions in the Bi sup 3+ sublattice of layered oxychloride catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Wuzong (Royal Institute of Great Britain, London (England) Univ. of Cambridge (England)); Jones, R.H.; Thomas, J.M.; Bieber, D. (Royal Institute of Great Britain, London (England))

    Although the ionic radii of trivalent bismuth and lanthanum are similar (96 and 106 pm, respectively), the structures of many pairs of corresponding ternary compounds (Bi{sub 2}CuO{sub 4} and La{sub 2}CuO{sub 4}, for instance) are quite different from one another. The authors interest in the solid solutions Bi{sub 1{minus}x}La{sub x}OCl stems from two sources. First, several compounds derived from BiOCl are good catalysts for the selective oxidation of methane. Second, many solid solutions of mixed oxides containing bismuth display remarkably wide varieties of superlattice ordering. They have examined, by selected area electron diffraction, specimens of the 1:3 and 1:1 solid solution (Bi{sub 0.25}La{sub 0.75}OCl and Bi{sub 0.5}La{sub 0.5}OCl, respectively).

  7. Moessbauer spectroscopic study of half-Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ksenofontov, V., E-mail: v.ksenofontov@uni-mainz.de; Kroth, K.; Reiman, S.; Casper, F.; Jung, V. [Johannes Gutenberg Universitaet, Institut fuer Anorganische Chemie und Analytische Chemie (Germany); Takahashi, M.; Takeda, M. [Toho University, Department of Chemistry, Faculty of Science (Japan); Felser, C. [Johannes Gutenberg Universitaet, Institut fuer Anorganische Chemie und Analytische Chemie (Germany)

    2006-02-15

    The family of half-Heusler compounds offers a variety of half-metallic ferromagnetic materials. We have applied the Moessbauer spectroscopy to study the atomic order, local surroundings and hyperfine fields to several half-Heusler compounds. {sup 121}Sb Moessbauer study of the compound CoMnSb revealed the presence of two nonequivalent antimony positions in the elementary cell and enabled to identify the structure. {sup 119m}Sn, {sup 155}Gd and {sup 197}Au Moessbauer spectroscopic studies were used to characterize the properties of ferromagnetic granular material based on the half-Heusler ferromagnet MnAuSn in the antiferromagnetic GdAuSn matrix.

  8. Electrochemistry and in-situ x-ray diffraction of InSb in lithium batteries.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C. S.; Vaughey, J. T.; Thackeray, M. M.; Sarakonsri, T.; Hackney, S. A.; Fransson, L.; Edstrom, K.; Thomas, J. O.; Chemical Engineering

    2000-08-01

    The electrochemical reactions of lithium with the intermetallic compound, InSb, were studied in lithium coin cells using laminate electrodes fabricated from either single-crystal InSb wafers or ball-milled samples. In-situ X-ray diffraction data show that the InSb zinc-blende framework is unstable to extensive reaction with lithium; In is extruded from a fixed Sb lattice during 'discharge' and is partially incorporated back into the lattice during 'charge'. Despite the loss of some In from the structure, the indium antimonide electrode provides capacities in excess of 300 mAh/g with excellent reversibility. Cyclic voltammetry was used to study the electrochemical processes in greater detail. Lithiated indium products are formed below {approx}600 mV versus Li. The electrode can be discharged at high rates, delivering 150 mAh/g at 3.6 mA/cm{sub 2} between 1.2 and 0.2 V versus Li. These data hold exciting prospects for the development of intermetallic insertion electrodes for practical room-temperature Li-ion cells.

  9. Structural transformation of Sb-based high-speed phase-change material.

    Science.gov (United States)

    Matsunaga, Toshiyuki; Kojima, Rie; Yamada, Noboru; Kubota, Yoshiki; Kifune, Kouichi

    2012-12-01

    The crystal structure of a phase-change recording material (the compound Ag(3.4)In(3.7)Sb(76.4)Te(16.5)) enclosed in a vacuum capillary tube was investigated at various temperatures in a heating process using a large Debye-Scherrer camera installed in BL02B2 at SPring-8. The amorphous phase of this material turns into a crystalline phase at around 416 K; this crystalline phase has an A7-type structure with atoms of Ag, In, Sb or Te randomly occupying the 6c site in the space group. This structure was maintained up to around 545 K as a single phase, although thermal expansion of the crystal lattice was observed. However, above this temperature, phase separation into AgInTe(2) and Sb-Te transpired. The first fragment, AgInTe(2), reliably maintained its crystal structure up to the melting temperature. On the other hand, the atomic configuration of the Sb-Te gradually varied with increasing temperature. This gradual structural transformation can be described as a continuous growth of the modulation period γ.

  10. Lattice location of the group V elements Sb, As, and P in ZnO

    CERN Document Server

    Wahl, Ulrich; Mendonça, Tânia; Decoster, Stefan

    2010-01-01

    Modifying the properties of ZnO by means of incorporating antimony, arsenic or phosphorus impurities is of interest since these group V elements have been reported in the literature among the few successful p-type dopants in this technologically promising II-VI compound. The lattice location of ion-implanted Sb, As, and P in ZnO single crystals was investigated by means of the electron emission channeling technique using the radioactive isotopes $^{124}$Sb, $^{73}$As and $^{33}$P and it is found that they preferentially occupy substitutional Zn sites while the possible fractions on substitutional O sites are a few percent at maximum. The lattice site preference is understandable from the relatively large ionic size of the heavy mass group V elements. Unfortunately the presented results cannot finally settle the interesting issue whether substitutional Sb, As or P on oxygen sites or Sb$_{Zn}$−2V$_{Zn}$, As$_{Zn}$−2V$_{Zn}$ or P$_{Zn}$−2V$_{Zn}$ complexes (as suggested in the literature) are responsible f...

  11. Determination of traces of Sb(III) using ASV in Sb-rich water samples affected by mining

    Energy Technology Data Exchange (ETDEWEB)

    Cidu, Rosa, E-mail: cidur@unica.it; Biddau, Riccardo; Dore, Elisabetta

    2015-01-07

    Highlights: • Antimony speciation affects the toxicity of this element. • A simple method for Sb(III) analyses in Sb-rich waters was developed. • Sb(III) was determined by ASV in water stabilized with tartaric and nitric acids. • Pre-concentration and/or separation of Sb(III) prior to analysis are not required. - Abstract: Chemical speciation [Sb(V) and Sb(III)] affects the mobility, bioavailability and toxicity of antimony. In oxygenated environments Sb(V) dominates whereas thermodynamically unstable Sb(III) may occur. In this study, a simple method for the determination of Sb(III) in non acidic, oxygenated water contaminated with antimony is proposed. The determination of Sb(III) was performed by anodic stripping voltammetry (ASV, 1–20 μg L{sup −1} working range), the total antimony, Sb(tot), was determined either by inductively coupled plasma mass spectrometry (ICP-MS, 1–100 μg L{sup −1} working range) or inductively coupled plasma optical emission spectrometry (ICP-OES, 100–10,000 μg L{sup −1} working range) depending on concentration. Water samples were filtered on site through 0.45 μm pore size filters. The aliquot for determination of Sb(tot) was acidified with 1% (v/v) HNO{sub 3}. Different preservatives, namely HCl, L(+) ascorbic acid or L(+) tartaric acid plus HNO{sub 3}, were used to assess the stability of Sb(III) in synthetic solutions. The method was tested on groundwater and surface water draining the abandoned mine of Su Suergiu (Sardinia, Italy), an area heavily contaminated with Sb. The waters interacting with Sb-rich mining residues were non acidic, oxygenated, and showed extreme concentrations of Sb(tot) (up to 13,000 μg L{sup −1}), with Sb(III) <10% of total antimony. The stabilization with L(+) tartaric acid plus HNO{sub 3} appears useful for the determination of Sb(III) in oxygenated, Sb-rich waters. Due to the instability of Sb(III), analyses should be carried out within 7 days upon the water collection. The main

  12. Synergy effects in mixed Bi2O3, MoO3 and V2O5 catalysts for selective oxidation of propylene

    DEFF Research Database (Denmark)

    Nguyen, Tien The; Le, Thang Minh; Truong, Duc Duc

    2012-01-01

    % Bi2Mo3O12 and 78.57 mol% BiVO4), corresponding to the compound Bi1-x/3V1-xMoxO4 with x = 0.45 (Bi0.85V0.55Mo0.45O4), exhibited the highest activity for the selective oxidation of propylene to acrolein. The mixed sample prepared chemically by a sol–gel method possessed higher activity than...

  13. Phase composition of Bi2O3 specimens doped with Ti, Zr and Hf

    Directory of Open Access Journals (Sweden)

    Poleti Dejan

    2012-01-01

    Full Text Available Powder mixtures of α-Bi2O3 containing 2, 5 and 10 mole % of TiO2, ZrO2 or HfO2 were homogenized, heated at 820ºC for 24 h and quenched in air. X-ray powder diffraction technique was used to characterize the prepared samples. In all cases metastable Bi2O3 polymorphs, γ-Bi2O3 or β-Bi2O3, are found as single or major phases. Addition of Ti4+ ions stabilizes γ-Bi2O3 polymorph, while either Zr4+ or Hf4+ ions stabilize β-Bi2O3 polymorph. In the samples with 2 and 5 mole % of TiO2 the presence of even two γ-Bi2O3 phases (Bi12TiO20 compound and a very low Ti-doped γ-Bi2O3 was established. Similarly, in the sample with 2 mole % of HfO2 two β-Bi2O3 phases were found. Phase composition of prepared samples, values of unit cell parameters and the appearance of two polymorphs with identical crystal structure but different unit cell parameters are discussed and compared with known data.

  14. BiOCl nanowire with hierarchical structure and its Raman features

    Energy Technology Data Exchange (ETDEWEB)

    Tian Ye [National Center for Nanoscience and Technology, No. 11, Beiyitiao, Zhongguancun, Beijing 100190 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Guo Chuanfei; Guo Yanjun; Wang Qi [National Center for Nanoscience and Technology, No. 11, Beiyitiao, Zhongguancun, Beijing 100190 (China); Liu Qian, E-mail: liuq@nanoctr.cn [National Center for Nanoscience and Technology, No. 11, Beiyitiao, Zhongguancun, Beijing 100190 (China)

    2012-01-01

    BiOCl is a promising V-VI-VII-compound semiconductor with excellent optical and electrical properties, and has great potential applications in photo-catalysis, photoelectric, etc. We successfully synthesize BiOCl nanowire with a hierarchical structure by combining wet etch (top-down) with liquid phase crystal growth (bottom-up) process, opening a novel method to construct ordered bismuth-based nanostructures. The morphology and lattice structures of Bi nanowires, {beta}-Bi{sub 2}O{sub 3} nanowires and BiOCl nanowires with the hierarchical structure are investigated by scanning electron microscope (SEM) and transition electron microscope (TEM). The formation mechanism of such ordered BiOCl hierarchical structure is considered to mainly originate from the highly preferred growth, which is governed by the lattice match between (1 1 0) facet of BiOCl and (2 2 0) or (0 0 2) facet of {beta}-Bi{sub 2}O{sub 3}. A schematic model is also illustrated to depict the formation process of the ordered BiOCl hierarchical structure. In addition, Raman properties of the BiOCl nanowire with the hierarchical structure are investigated deeply.

  15. Rich stoichiometries of stable Ca-Bi system: Structure prediction and superconductivity

    Science.gov (United States)

    Dong, Xu; Fan, Changzeng

    2015-03-01

    Using a variable-composition ab initio evolutionary algorithm implemented in the USPEX code, we have performed a systematic search for stable compounds in the Ca-Bi system at different pressures. In addition to the well-known tI12-Ca2Bi and oS12-CaBi2, a few more structures were found by our calculations, among which phase transitions were also predicted in Ca2Bi (tI12 --> oI12 --> hP6), Ca3Bi2 (hP5 --> mC20 --> aP5) and CaBi (tI2 --> tI8), as well as a new phase (Ca3Bi) with a cF4 structure. All the newly predicted structures can be both dynamically and thermodynamically stable with increasing pressure. The superconductive properties of cF4-CaBi3, tI2-CaBi and cF4-Ca3Bi were studied and the superconducting critical temperature Tc can be as high as 5.16, 2.27 and 5.25 K, respectively. Different superconductivity behaviors with pressure increasing have been observed by further investigations.

  16. Liquidus Projection and Isothermal Section of the Sb-Se-Sn System

    Science.gov (United States)

    Chang, Jui-shen; Chen, Sinn-wen

    2017-12-01

    Sb-Se-Sn ternary alloys are promising chalcogenide materials. The liquidus projection and 673.2 K (400 °C) isothermal section of the Sb-Se-Sn ternary system are determined. Numerous Sb-Se-Sn alloys are prepared, and their primary solidification phases are examined. In addition to the three terminal phases, (Sb), (Se) and (Sn), there are Sb2Sn3, SbSn, SnSe, SnSe2, Sb2Se3, Sn2Sb9Se9, and SnSb2Se4 phases. In addition, there are two miscibility gaps along the Sb-Se and Se-Sn and sides. There are ten invariant reactions in the Sb-Se-Sn ternary system, and seven of them are experimentally determined in this study. The lowest reaction temperature of determined invariant reaction is L + SbSn = (Sn) + SnSe at 515.4 K ± 5 K (242.2 °C ± 5 °C). There are nine tie-triangles, which are Liquid + SbSn + SnSe, SbSn + SnSe + (Sb), SnSe + (Sb) + Sn2Sb9Se9, (Sb) + Sb2Se3 + Sn2Sb9Se9, SnSe + Sn2Sb9Se9 + SnSb2Se4, Sb2Se3 + Sn2Sb9Se9 + SnSb2Se4, SnSe + SnSe2 + SnSb2Se4, SnSe2 + SnSb2Se4 + Sb2Se3, and SnSe2 + Sb2Se3 + Liquid in the 673.2 K (400 °C) isothermal section of the Sb-Se-Sn ternary system.

  17. Diffusion couple studies of the Ni-Bi-Sn system

    Directory of Open Access Journals (Sweden)

    Vassilev G.

    2012-01-01

    Full Text Available Investigations of Ni-Bi-Sn system were performed in order to inquire the phase diagram and to assess some diffusion kinetic parameters. For this purpose diffusion couples consisting of solid nickel (preliminary electroplated with tin and liquid Bi-Sn phase were annealed at 370 °C. Three compositions (0.8, 0.6 and 0.4 mole fractions Sn of the Bi-Sn melts were chosen. Annealing times from 24 to 216 h were applied. The phase and chemical compositions of the contact zone were determined by means of electron scanning microscope. It was confirmed that the diffusion layers consist mainly of Ni3Sn4 but other intermetallic phases grow as well. For the first time metastable Ni-Sn phases as NiSn and NiSn8 (NiSn9 were observed in metallurgical alloys (i.e. not in electroplated samples. The existence of a ternary compound previously reported in the literature was confirmed. More than one ternary Ni-Bi-Sn compounds might possibly be admitted. A growth coefficient of (2.29 ± 0.02 x 10-15 m2 s-1 was obtained. It was found that the apparent activation energy for diffusion layers growth (18 ± 8 kJ mol-1 is inferior to that one assessed at growth from solid state Bi-Sn mixtures (88 ± 12 kJ mol-1.

  18. Gold and palladium minerals (including empirical PdCuBiSe3) from the former Roter Bär mine, St. Andreasberg, Harz Mountains, Germany: a result of low-temperature, oxidising fluid overprint

    Science.gov (United States)

    Cabral, Alexandre Raphael; Ließmann, Wilfried; Lehmann, Bernd

    2015-10-01

    At Roter Bär, a former underground mine in the polymetallic deposits of St. Andreasberg in the middle-Harz vein district, Germany, native gold and palladium minerals occur very locally in clausthalite-hematite pockets of few millimetres across in carbonate veinlets. The native gold is a Au-Ag intermetallic compound and the palladium minerals are characterised as mertieite-II [Pd8(Sb,As)3] and empirical PdCuBiSe3 with some S. The latter coexists with bohdanowiczite (AgBiSe2), a mineral that is stable below 120 °C. The geological setting of Roter Bär, underneath a post-Variscan unconformity, and its hematite-selenide-gold association suggest that oxidising hydrothermal brines of low temperature were instrumental to the Au-Pd mineralisation. The Roter Bär Au-Pd mineralisation can be explained by Permo-Triassic, red-bed-derived brines in the context of post-Variscan, unconformity-related fluid overprint.

  19. Sorghum Phytochrome B Inhibits Flowering in Long Days by Activating Expression of SbPRR37 and SbGHD7, Repressors of SbEHD1, SbCN8 and SbCN12

    Science.gov (United States)

    Yang, Shanshan; Murphy, Rebecca L.; Morishige, Daryl T.; Klein, Patricia E.; Rooney, William L.; Mullet, John E.

    2014-01-01

    Light signaling by phytochrome B in long days inhibits flowering in sorghum by increasing expression of the long day floral repressors PSEUDORESPONSE REGULATOR PROTEIN (SbPRR37, Ma1) and GRAIN NUMBER, PLANT HEIGHT AND HEADING DATE 7 (SbGHD7, Ma6). SbPRR37 and SbGHD7 RNA abundance peaks in the morning and in the evening of long days through coordinate regulation by light and output from the circadian clock. 58 M, a phytochrome B deficient (phyB-1, ma3R) genotype, flowered ∼60 days earlier than 100 M (PHYB, Ma3) in long days and ∼11 days earlier in short days. Populations derived from 58 M (Ma1, ma3R, Ma5, ma6) and R.07007 (Ma1, Ma3, ma5, Ma6) varied in flowering time due to QTL aligned to PHYB/phyB-1 (Ma3), Ma5, and GHD7/ghd7-1 (Ma6). PHYC was proposed as a candidate gene for Ma5 based on alignment and allelic variation. PHYB and Ma5 (PHYC) were epistatic to Ma1 and Ma6 and progeny recessive for either gene flowered early in long days. Light signaling mediated by PhyB was required for high expression of the floral repressors SbPRR37 and SbGHD7 during the evening of long days. In 100 M (PHYB) the floral activators SbEHD1, SbCN8 and SbCN12 were repressed in long days and de-repressed in short days. In 58 M (phyB-1) these genes were highly expressed in long and short days. Furthermore, SbCN15, the ortholog of rice Hd3a (FT), is expressed at low levels in 100 M but at high levels in 58 M (phyB-1) regardless of day length, indicating that PhyB regulation of SbCN15 expression may modify flowering time in a photoperiod-insensitive manner. PMID:25122453

  20. Sorghum phytochrome B inhibits flowering in long days by activating expression of SbPRR37 and SbGHD7, repressors of SbEHD1, SbCN8 and SbCN12.

    Directory of Open Access Journals (Sweden)

    Shanshan Yang

    Full Text Available Light signaling by phytochrome B in long days inhibits flowering in sorghum by increasing expression of the long day floral repressors PSEUDORESPONSE REGULATOR PROTEIN (SbPRR37, Ma1 and GRAIN NUMBER, PLANT HEIGHT AND HEADING DATE 7 (SbGHD7, Ma6. SbPRR37 and SbGHD7 RNA abundance peaks in the morning and in the evening of long days through coordinate regulation by light and output from the circadian clock. 58 M, a phytochrome B deficient (phyB-1, ma3R genotype, flowered ∼60 days earlier than 100 M (PHYB, Ma3 in long days and ∼11 days earlier in short days. Populations derived from 58 M (Ma1, ma3R, Ma5, ma6 and R.07007 (Ma1, Ma3, ma5, Ma6 varied in flowering time due to QTL aligned to PHYB/phyB-1 (Ma3, Ma5, and GHD7/ghd7-1 (Ma6. PHYC was proposed as a candidate gene for Ma5 based on alignment and allelic variation. PHYB and Ma5 (PHYC were epistatic to Ma1 and Ma6 and progeny recessive for either gene flowered early in long days. Light signaling mediated by PhyB was required for high expression of the floral repressors SbPRR37 and SbGHD7 during the evening of long days. In 100 M (PHYB the floral activators SbEHD1, SbCN8 and SbCN12 were repressed in long days and de-repressed in short days. In 58 M (phyB-1 these genes were highly expressed in long and short days. Furthermore, SbCN15, the ortholog of rice Hd3a (FT, is expressed at low levels in 100 M but at high levels in 58 M (phyB-1 regardless of day length, indicating that PhyB regulation of SbCN15 expression may modify flowering time in a photoperiod-insensitive manner.

  1. Thermal analysis and phase diagrams of the LiF BiF{sub 3} e NaF BiF{sub 3} systems; Analise termica e diagramas de fase dos sistemas LiF-BiF{sub 3} e NaF-BiF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Gerson Hiroshi de Godoy

    2013-07-01

    Investigations of the binary systems LiF-BiF{sub 3} and NaF-BiF{sub 3} were performed with the objective of clarifying the thermal behavior and phase equilibria of these systems and their intermediary phases, an important requisite for high-quality crystal growth. Several samples in the entire range of compositions (0 to 100 mol% BiF{sub 3}) of both systems were subjected to experiments of differential thermal analysis (DTA) and thermogravimetry (TG), and also of differential scanning calorimetry (DSC). A few specific compositions were selected for X-ray diffraction to supplement the experimental data. Due to the high vulnerability of BiF{sub 3} to oxygen contamination, its volatility and propensity to destroy metal parts upon heating, it was necessary to determine the optimal conditions for thermal analysis before investigating the systems themselves. Phase relations in the system LiF-BiF{sub 3} were completely clarified and a phase diagram was calculated and evaluated via the commercial software Factsage. The diagram itself consists in a simple peritectic system in which the only intermediary compound, LiBiF{sub 4}, decomposes into LiF and a liquid phase. The NaF-BiF{sub 3} system could not be completely elucidated and the phase relations in the NaF poor side (> 50% BiF{sub 3}) are still unknown. In the NaF rich side, however, the possible peritectoid decomposition of the compound NaBiF{sub 4} was identified. In both systems X-ray diffraction yielded crystal structures discrepant with the literature for the intermediary phases, LiBiF{sub 4}, NaBiF{sub 4} and a solid solution of NaF and BiF{sub 3} called {sup I.} The observed structures remain unknown and explanations for the discrepancies were proposed. (author)

  2. [Determination of 24 metal elements and their compounds in air of workplace by ICP-AES].

    Science.gov (United States)

    Wang, Xiang; Qiu, Jianguo; Zhao, Zhonglin; Guo, Ying

    2014-06-01

    To establish a method for determination of the levels of 24 metal elements and their compounds in the air of workplace by inductively coupled plasma-atomic emission spectroscopy (ICP- AES). Sampling filters were digested by microwave, and diluted to 25 ml. Twenty-four elements (Mg, Ni, K, Mo, Zn, Ca, Ba, Pb, Mn, Cd, Cr, Co, Cu, Sr, Bi, Tl, Sn, Li, Sb, Zr, In, V, Y, and Be) were simultaneously measured by ICP-AES. The detection limits for 24 elements were 0.001∼0.029 mg/L; liner correlation coefficient r values were all equal to or above 0.9994; the relative standard derivations were less than 5%; the recovery rates were 91.2%∼103.9%; the degradation rates in 7 days were less than 9.7%. ICP-AES technique is a simple, rapid, accurate, and reliable method, which can be used to measure 24 metal elements and their compounds in the air of workplace.

  3. In As{sub 1–x}Sb{sub x} heteroepitaxial structures on compositionally graded GaInSb and AlGaInSb buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Guseynov, R. R.; Tanriverdiyev, V. A. [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan); Kipshidze, G., E-mail: gela.kishidze@stonybrook.ede [Stony Brook, Stony Brook University (United States); Aliyeva, Ye. N.; Aliguliyeva, Kh. V.; Abdullayev, N. A., E-mail: abnadir@mail.ru; Mamedov, N. T. [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan)

    2017-04-15

    Unrelaxed InAs{sub 1–x}Sb{sub x} (x = 0.43 and 0.38) alloy layers are produced by molecular-beam epitaxy on compositionally graded GaInSb and AlGaInSb buffer layers. The high quality of the thin films produced is confirmed by the results of high-resolution X-ray diffraction analysis and micro-Raman studies. The twomode type of transformation of the phonon spectra of InAs{sub 1–x}Sb{sub x} alloys is established.

  4. Effect of InSb/In0.9Al0.1Sb superlattice buffer layer on the structural and electronic properties of InSb films

    Science.gov (United States)

    Zhao, Xiaomeng; Zhang, Yang; Guan, Min; Cui, Lijie; Wang, Baoqiang; Zhu, Zhanping; Zeng, Yiping

    2017-07-01

    The effect of InSb/In0.9Al0.1Sb buffer layers on InSb thin films grown on GaAs (0 0 1) substrate by molecular beam epitaxy (MBE) is investigated. The crystal quality and the surface morphology of InSb are characterized by XRD and AFM. The carrier transport property is researched through variable temperature hall test. The sharp interface between InSb/In0.9Al0.1Sb is demonstrated important for the high quality InSb thin film. We try different superlattice buffer layers by changing ratios, 2-0.5, thickness, 300-450 nm, and periods, 20-50. According to the function of the dislocation density to the absolute temperature below 150 K with different periods of SL buffers, we can find that the number of periods of superlattice is a major factor to decrease the density of threading dislocations. With the 50 periods SL buffer layer, the electron mobility of InSb at the room temperature and liquid nitrogen cooling temperature is ∼63,000 and ∼4600 cm2/V s, respectively. We deduce that the interface in the SL structure works as a filter layer to prevent the dislocation propagating to the upper InSb thin films.

  5. Physico-chemical properties of Sb-rich (Sb, In)–Te thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hromádko, L., E-mail: Ludek.Hromadko@upce.cz [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10 (Czech Republic); Přikryl, J.; Střižík, L. [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10 (Czech Republic); Košt’ál, P. [Department of Inorganic Technology, Faculty of Chemical Technology, University of Pardubice, Doubravice 41, Pardubice 532 10 (Czech Republic); Beneš, L. [Joint Laboratory of Solid State Chemistry of Institute of Macromolecular Chemistry of the Academy of Sciences of the Czech Republic and University of Pardubice, Faculty of Chemical Technology, Studentská 95, Pardubice 532 10 (Czech Republic); Frumar, M. [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 532 10 (Czech Republic)

    2014-12-25

    Highlights: • The difference of electrical sheet resistance between amorphous and crystalline state is more than 3 orders. • The crystallization temperature T{sub c} of the prepared films increases with increasing content of indium. • The activation energy of crystallization E{sub a} increased with increasing content of indium. • The prepared thin films could be applied for electrical non-volatile phase change memories. - Abstract: The phase change materials of the system Sb{sub 70−x}In{sub x}Te{sub 30} (x = 0, 7 and 14) were studied. The thin films prepared by thermal flash evaporation were amorphous with high electrical sheet resistance (R{sub s}) (≈10{sup 6} Ω/sqr., T = 300 K). When heated, the resistance dropped to 10–10{sup 2} Ω/sqr. due to crystallization of the films. The crystallization temperatures were 113, 158 and 183 °C for Sb{sub 70}Te{sub 30}, Sb{sub 63}In{sub 7}Te{sub 30} and Sb{sub 56}In{sub 14}Te{sub 30}, respectively. The activation energies of crystallization as evaluated by Kissinger’s plot were 2.42, 2.72 and 3.15 eV for Sb{sub 70}Te{sub 30}, Sb{sub 63}In{sub 7}Te{sub 30} and Sb{sub 56}In{sub 14}Te{sub 30}, respectively. The optical band gap of amorphous films increases with increasing content of indium from 0.38 to 0.47 eV. Values of refractive index were found in range of 5.43–4.77 (λ = 1500 nm) for amorphous state and 7.06–5.89 for crystalline state in dependence on composition. They decreased with increasing content of indium.

  6. Magnetic, dielectric properties, and scaling behaviors of Aurivillius compounds Bi{sub 6−x∕3}Fe{sub 2}Ti{sub 3−2x}(WCo){sub x}O{sub 18} (0 ≤ x ≤ 0.15)

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, X. Z.; Yang, J., E-mail: jyang@issp.ac.cn; Yuan, B.; Tang, X. W.; Zhang, K. J.; Zhu, X. B.; Song, W. H.; Dai, J. M., E-mail: jmdai@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Song, D. P. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Sun, Y. P. [High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031 (China); Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-03-21

    We investigate the structural, magnetic, dielectric properties, and scaling behaviors of Aurivillius compounds Bi{sub 6−x∕3}Fe{sub 2}Ti{sub 3−2x}(WCo){sub x}O{sub 18} (0 ≤ x ≤ 0.15). The room-temperature weak ferromagnetism is observed for the W/Co co-doped samples. The results of the dielectric constant ε{sub r}, complex impedance Z″, the dc conductivity σ{sub dc}, and hopping frequency f{sub H} manifest that the dielectric relaxation of the x = 0 sample and the doped samples in the dielectric anomaly region (450–750 K) can be ascribed to the trap-controlled ac conduction around the doubly ionized oxygen vacancies and the localized hopping process of oxygen vacancies, respectively. The scaling behaviors reveal that the dynamic process of both electrons in the x = 0 sample and oxygen vacancies in the doped samples is temperature independent. The ferroelectric Curie-temperature T{sub c} decreases slightly from 973 K to 947 K with increasing the doping level of W/Co. In addition, the dielectric loss exhibits a dielectric relaxation above 800 K with the rather large activation energies (1.95 eV ≤ E{sub a} ≤ 2.72 eV)

  7. Quantitative HPLC-ICP-MS analysis of antimony redox speciation in complex sample matrices: new insights into the Sb-chemistry causing poor chromatographic recoveries.

    Science.gov (United States)

    Hansen, Claus; Schmidt, Bjørn; Larsen, Erik H; Gammelgaard, Bente; Stürup, Stefan; Hansen, Helle Rüsz

    2011-03-07

    In solution antimony exists either in the pentavalent or trivalent oxidation state. As Sb(III) is more toxic than Sb(V), it is important to be able to perform a quantitative speciation analysis of Sb's oxidation state. The most commonly applied chromatographic methods used for this redox speciation analysis do, however, often show a low chromatographic Sb recovery when samples of environmental or biological origin are analysed. In this study we explored basal chemistry of antimony and found that formation of macromolecules, presumably oligomeric and polymeric Sb(V) species, is the primary cause of low chromatographic recoveries. A combination of HPLC-ICP-MS, AFFF-ICP-MS and spin-filtration was applied for analysis of model compounds and biological samples. Quantitative chromatographic Sb redox speciation analysis was possible by acidic hydrolysis of the antimony polymers prior to analysis. Sample treatment procedures were studied and the optimum solution was acidic hydrolysis by 1 M HCl in the presence of chelating ligands (EDTA, citrate), which stabilise the trivalent oxidation state of Sb.

  8. Large-format multi-wafer production of 5" GaSb-based photodetectors by molecular beam epitaxy

    Science.gov (United States)

    Loubychev, Dmitri; Fastenau, Joel M.; Kattner, Michael; Frey, Phillip; Liu, Amy W. K.; Furlong, Mark J.

    2017-02-01

    GaSb and its heterostructures grown by molecular beam epitaxy (MBE) have received much attention given their application in a wide range of mid-wave and long-wave IR photodetector applications. With the maturation of the MBE growth process, focus is now turned to improving manufacturing readiness and the transition to the production of large-format wafers. We will discuss the transition from the development of early detector layer structures on 2" diameter GaSb substrates, through today's 3"/4" production standard, and to the onset of 5" pilot production from the perspective of volume compound semiconductor manufacturing. We will report on the growth of 5" GaSb-based MWIR nBn detector structures using a large format 5×5" production MBE platform. Structural and optical properties, as well as electrical data from large-area mesa diodes will be presented and compared with results achieved with smaller batch size MBE reactor platform.

  9. Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

    Directory of Open Access Journals (Sweden)

    M. Ruiz-Osés

    2014-12-01

    Full Text Available Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100 substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 Å . The antimony crystalline structure dissolved upon potassium deposition, eventually recrystallizing upon further deposition into K-Sb crystalline modifications. This transition, as well as the conversion of potassium antimonide to K2CsSb upon cesium deposition, is correlated with changes in the quantum efficiency.

  10. Microbiological reduction of Sb(V) in anoxic freshwater sediments

    Science.gov (United States)

    Oremland, Ronald S.; Kulp, Thomas R.; Miller, Laurence G.; Braiotta, Franco; Webb, Samuel M.; Kocar, Benjamin D; Blum, Jodi S.

    2014-01-01

    Microbiological reduction of millimolar concentrations of Sb(V) to Sb(III) was observed in anoxic sediments from two freshwater settings: (1) a Sb- and As-contaminated mine site (Stibnite Mine) in central Idaho and 2) an uncontaminated suburban lake (Searsville Lake) in the San Francisco Bay Area. Rates of Sb(V) reduction in anoxic sediment microcosms and enrichment cultures were enhanced by amendment with lactate or acetate as electron donors but not by H2, and no reduction occurred in sterilized controls. Addition of 2-14C-acetate to Stibnite Mine microcosms resulted in the production of 14CO2 coupled to Sb(V) reduction, suggesting that this process proceeds by a dissimilatory respiratory pathway in those sediments. Antimony(V) reduction in Searsville Lake sediments was not coupled to acetate mineralization and may be associated with Sb-resistance. The microcosms and enrichment cultures also reduced sulfate, and the precipitation of insoluble Sb(III)-sulfide complexes was a major sink for reduced Sb. The reduction of Sb(V) by Stibnite Mine sediments was inhibited by As(V), suggesting that As(V) is a preferred electron acceptor for the indigenous community. These findings indicate a novel pathway for anaerobic microbiological respiration and suggest that communities capable of reducing high concentrations of Sb(V) commonly occur naturally in the environment.

  11. Non-equilibrium Green's function calculation of AlGaAs-well-based and GaSb-based terahertz quantum cascade laser structures

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, H., E-mail: yasuda@nict.go.jp; Hosako, I. [National Institute of Information and Communications Technology, 4-2-1 Nukui-Kitamachi, Koganei, Tokyo 184-8795 (Japan)

    2015-03-16

    We investigate the performance of terahertz quantum cascade lasers (THz-QCLs) based on Al{sub x}Ga{sub 1−x}As/Al{sub y}Ga{sub 1−y}As and GaSb/AlGaSb material systems to realize higher-temperature operation. Calculations with the non-equilibrium Green's function method reveal that the AlGaAs-well-based THz-QCLs do not show improved performance, mainly because of alloy scattering in the ternary compound semiconductor. The GaSb-based THz-QCLs offer clear advantages over GaAs-based THz-QCLs. Weaker longitudinal optical phonon–electron interaction in GaSb produces higher peaks in the spectral functions of the lasing levels, which enables more electrons to be accumulated in the upper lasing level.

  12. Using the Semiconductors Materials of InSb-ZnTe System in Sensors for Gas Control

    Science.gov (United States)

    Shubenkova, E. G.

    2017-04-01

    The samples of thin film semiconductor compounds InSb, ZnTe and solid solutions based on them were obtained by vapor deposition of components on a dielectric substrate in a vacuum, followed by annealing and their surface properties in CO, O2 and NH3 gas atmospheres were investigated. Identification of the samples was carried out by X-ray diffraction techniques. In the temperature range 253 ÷ 403 K and a pressure range of 1÷12 Pa the gas adsorption was measured by piezoelectric microbalance technique. In order to establish the basic regularities of processes flowing on samples surface in addition to the electrophisical were used Infrared and Raman spectroscopic measurements. The resulting addiction “surface property - composition” is extreme and have allowed to determine solid solution InSb0,95-ZnTe0,05 as the most sensitive to the presence of ammonia, selective and this sample exhibits a negligible oxidation of surface.

  13. BiI3 Crystals for High Energy Resolution Gamma-Ray Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nino, Juan C. [Univ. of Florida, Gainesville, FL (United States); Baciak, James [Univ. of Florida, Gainesville, FL (United States); Johns, Paul [Univ. of Florida, Gainesville, FL (United States); Sulekar, Soumitra [Univ. of Florida, Gainesville, FL (United States); Totten, James [Univ. of Florida, Gainesville, FL (United States); Nimmagadda, Jyothir [Univ. of Florida, Gainesville, FL (United States)

    2017-04-12

    BiI3 had been investigated for its unique properties as a layered compound semiconductor for many decades. However, despite the exceptional atomic, physical, and electronic properties of this material, good resolution gamma ray spectra had never been reported for BiI3. The shortcomings that previously prevented BiI3 from reaching success as a gamma ray sensor were, through this project, identified and suppressed to unlock the performance of this promising compound. Included in this work were studies on a number of methods which have, for the first time, enabled BiI3 to exhibit spectral performance rivaling many other candidate semiconductors for room temperature gamma ray sensors. New approaches to crystal growth were explored that allow BiI3 spectrometers to be fabricated with up to 2.2% spectral resolution at 662 keV. Fundamental studies on trap states, dopant incorporation, and polarization were performed to enhance performance of this compound. Additionally, advanced detection techniques were applied to display the capabilities of high quality BiI3 spectrometers. Overall, through this work, BiI3 has been revealed as a potentially transformative material for nuclear security and radiation detection sciences.

  14. Optical and structural properties of MOVPE-grown GaInSb/GaSb quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, Viera, E-mail: viera.wagener@nmmu.ac.z [Physics Department, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Olivier, E.J.; Botha, J.R. [Physics Department, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2009-12-15

    This paper reports on the optical and structural properties of strained type-I Ga{sub 1-x}In{sub x}Sb quantum wells embedded in GaSb from a metal-organic vapour phase epitaxial growth perspective. Photoluminescence measurements and transmission electron microscopy were used to evaluate the effect of the growth temperature on the quality of Ga{sub 1-x}In{sub x}Sb strained layers with varied alloy compositions and thicknesses. Although the various factors contributing to the overall quality of the strained layers are difficult to separate, the quantum well characteristics are significantly altered by the growth temperature. Despite the high growth rates (approx2 nm/s), quantum wells grown at 607 deg. C display photoluminescence emissions with full-width at half-maximum of 3.5-5.0 meV for an indium solid content (x) up to 0.15.

  15. Optical Characterization of AlAsSb Digital Alloy and Random Alloy on GaSb

    Directory of Open Access Journals (Sweden)

    Bor-Chau Juang

    2017-10-01

    Full Text Available III-(As, Sb alloys are building blocks for various advanced optoelectronic devices, but the growth of their ternary or quaternary materials are commonly limited by spontaneous formation of clusters and phase separations during alloying. Recently, digital alloy growth by molecular beam epitaxy has been widely adopted in preference to conventional random alloy growth because of the extra degree of control offered by the ordered alloying. In this article, we provide a comparative study of the optical characteristics of AlAsSb alloys grown lattice-matched to GaSb using both techniques. The sample grown by digital alloy technique showed stronger photoluminescence intensity, narrower peak linewidth, and larger carrier activation energy than the random alloy technique, indicating an improved optical quality with lower density of non-radiative recombination centers. In addition, a relatively long carrier lifetime was observed from the digital alloy sample, consistent with the results obtained from the photoluminescence study.

  16. Preparation and optimization of thermoelectric properties of Bi2Te3 based alloys using the waste particles as raw materials from the cutting process of the zone melting crystal rods

    Science.gov (United States)

    Xiang, Qiusheng; Fan, Xi'an; Han, Xuewu; Zhang, Chengcheng; Hu, Jie; Feng, Bo; Jiang, Chengpeng; Li, Guangqiang; Li, Yawei; He, Zhu

    2017-12-01

    The p-type Bi2Te3 alloys were prepared using the waste particles from the cutting process of the zone melting crystal rods as the main raw materials by impurity removal process including washing, carbon monoxide reduction and vacuum metallurgical process. The thermoelectric properties of the Bi2Te3 based bulk materials were optimized by component adjustment, second smelting and resistance pressing sintering (RPS) process. All evidences confirmed that most of impurities from the line cutting process and the oxidation such as Sb2O3, Bi2O3 and Bi2Te4O11 could be removed by carbon monoxide reduction and vacuum metallurgical process adopted in this work, and the recycling yield was higher than 97%. Appropriate component adjustment treatment was used to optimize the carrier content and corresponding thermoelectric properties. Lastly, a Bi0.36Sb1.64Te3 bulk was obtained and its power factor (PF) could reach 4.24 mW m-1 K-2 at 300 K and the average PF value was over 3.2 mW m-1 K-2 from 300 K to 470 K, which was equivalent with the thermoelectric performance of the zone melting products from high purity elements Bi, Te and Sb. It was worth mentioning that the recovery process introduced here was a simple, low-cost, high recovery rate and green recycling technology.

  17. Electronic structure and transport properties of Ba{sub 2}Cd{sub 2}Pn{sub 3} (Pn = As and Sb): An efficient materials for energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H., E-mail: maalidph@yahoo.co.uk [New Technologies - Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia)

    2016-06-15

    The full potential method within the recently modified Becke-Johnson potential explore that the Ba{sub 2}Cd{sub 2}Pn{sub 3} (Pn = As and Sb) compounds are narrow band gap semiconductors of about 0.49 and 0.32 eV, which confute the finding of the previous TB-LMTO-ASA calculation that Ba{sub 2}Cd{sub 2}Sb{sub 3} is a poor metal. It has been found that there are subtle difference in band desperations of the two compounds, resulting in significant influence on the electronic and transport properties, taking into account the size and the electro-negativity differences between As and Sb atoms. Calculation show that there exists a strong hybridization between the orbitals which may lead to form covalent bonding which is more favorable for the transport of the carriers than ionic one. The electronic structure, the anisotropy and the inter-atomic interactions are further analyzed by calculating the valence electronic charge density distribution in two crystallographic planes. The semi-classical Boltzmann theory as incorporated in BoltzTraP code was used to calculate the transport properties of Ba{sub 2}Cd{sub 2}As{sub 3} and Ba{sub 2}Cd{sub 2}Sb{sub 3} at different temperatures and chemical potentials to ascertain the influence of temperatures and substituting As by Sb on the transport properties. The carries mobility decreases with increasing the temperature also with increasing the carriers concentration. We have observed that substituting As by Sb lead to increase the carries mobility of Ba{sub 2}Cd{sub 2}Sb{sub 3} along the whole temperature interval and the carries concentration range. It has been found that Ba{sub 2}Cd{sub 2}As{sub 3} exhibit higher carriers concentration, electronic electrical conductivity and Seebeck coefficient than that of Ba{sub 2}Cd{sub 2}Sb{sub 3} along the investigated temperature range. The highest value of Seebeck coefficient occurs at 300 K, which show good agreement with the experimental data. The power factor increases linearly with

  18. SB223412, a neurokinin-3 receptor-selective antagonist, suppresses testosterone secretion in male guinea pigs.

    Science.gov (United States)

    Nakamura, Sho; Ito, Yoshiko; Yamamoto, Koki; Takahashi, Chudai; Dai, Mingdao; Tanahashi, Miyu; Uenoyama, Yoshihisa; Tsukamura, Hiroko; Oishi, Shinya; Maeda, Kei-Ichiro; Matsuda, Fuko

    2017-10-15

    Guinea pigs are important zoo animals and have been recommended for animal-assisted activities or therapy, however there are problems concerning testosterone inducing aggressive or sexual behaviors in male guinea pigs. Testicular testosterone secretion is regulated by pulsatile gonadotropin releasing hormone (GnRH)/luteinizing hormone (LH) release in mammals. The mechanism generating GnRH/LH pulses is thought to be governed by kisspeptin neurons, which coexpress neurokinin B (NKB) and dynorphin A (Dyn), in the arcuate nucleus (ARC). Kisspeptin neurons in the ARC are frequently referred to as KNDy neurons. The purpose of this study was to examine whether the antagonization of NKB-neurokinin-3 receptor (NK3R) signaling can manipulate testosterone secretion in male guinea pigs. A single subcutaneous administration or 7 days of oral administration of an NK3R-selective antagonist, SB223412 (50 mg/body), significantly decreased plasma testosterone levels in male guinea pigs. In vitro binding assays confirmed that SB223412 has a high affinity to guinea pig NK3R. These results suggest that SB223412 could be used as an orally-available compound to suppress testosterone levels in male guinea pigs. Double labeling in situ hybridization of kisspeptin and either NKB or Dyn showed that kisspeptin-expressing neurons contained NKB (77.9%) or Dyn (62.3%) in the ARC, suggesting the presence of KNDy neurons in the ARC of guinea pigs. In conclusion, the present study shows that SB223412 could be a candidate compound to suppress testosterone secretion in male guinea pigs for controlling sexual and aggressive behaviors in the species. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Study of dual color infrared photodetection from n-GaSb/n-InAsSb heterostructures

    Directory of Open Access Journals (Sweden)

    Jinchao Tong

    2016-02-01

    Full Text Available We report detailed investigation of n-GaSb/n-InAsSb heterostructure photodetectors for infrared photodetection at different temperatures and biases. Our results show that the heterostructure photodetectors are capable of dual color photodetections at a fixed forward bias with its highest responsivity occurred at room temperature; With the decrease of the forward bias, a turning point, at which the photocurrent changes its direction, exist and the corresponding voltage values increases with the decrease of temperature; At all reverse biases, the photocurrents flow in the same direction but the maximum current occurs at about 205 K. A new model is proposed, which can well explain all the observations.

  20. Anisotropic magnetization and transport properties of RAgSb2 (R=Y, La-Nd, Sm, Gd-Tm)

    Energy Technology Data Exchange (ETDEWEB)

    Myers, Kenneth D. [Iowa State Univ., Ames, IA (United States)

    1999-11-08

    This study of the RAgSb2 series of compounds arose as part of an investigation of rare earth intermetallic compounds containing antimony with the rare earth in a position with tetragonal point symmetry. Materials with the rare earth in a position with tetragonal point symmetry frequently manifest strong anisotropies and rich complexity in the magnetic properties, and yet are simple enough to analyze. Antimony containing intermetallic compounds commonly possess low carrier densities and have only recently been the subject of study. Large single grain crystals were grown of the RAgSb2 (R=Y, La-Nd, Sm, Gd-Tm) series of compounds out of a high temperature solution. This method of crystal growth, commonly known as flux growth is a versatile method which takes advantage of the decreasing solubility of the target compound with decreasing temperature. Overall, the results of the crystal growth were impressive with the synthesis of single crystals of LaAgSb2 approaching one gram. However, the sample yield diminishes as the rare earth elements become smaller and heavier. Consequently, no crystals could be grown with R=Yb or Lu. Furthermore, EuAgSb2 could not be synthesized, likely due to the divalency of the Eu ion. For most of the RAgSb2 compounds, strong magnetic anisotropies are created by the crystal electric field splitting of the Hund's rule ground state. This splitting confines the local moments to lie in the basal plane (easy plane) for the majority of the members of the series. Exceptions to this include ErAgSb2 and TmAgSb2, which have moments along the c-axis (easy axis) and CeAgSb2, which at intermediate temperatures has an easy plane, but exchange coupling at low temperatures is anisotropic with an easy axis. Additional anisotropy is also observed within the basal plane of DyAgSb2, where the moments are restricted to align along one of the <110> axes. Most of

  1. Elastic properties of the filled and unfilled skutterudite compounds

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Y [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Fujino, T [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Kikuchi, F [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Tanizawa, T [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Sun, P [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Nakamura, M [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Yoshino, G [Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Ochiai, A [Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan); Sugawara, H [Faculty of Integrated Arts and Sciences, University of Tokushima, Tokushima, 770-8502 (Japan); Kikuchi, D [Department of Physics, Tokyo Metropolitan University, Hachioji, 192-0397 (Japan); Sato, H [Department of Physics, Tokyo Metropolitan University, Hachioji, 192-0397 (Japan); Yoshizawa, M [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan)

    2007-12-15

    Ultrasonic measurements were made on a single crystal of the unfilled skutterudite compounds RhSb{sub 3} and IrSb{sub 3} and compare with that of the filled skutterudite PrOs{sub 4} Sb{sub 12} to elucidate the role of the guest ions Pr. A characteristic increase was observed around 30 K in the temperature dependence of elastic constants (C{sub 11}-C{sub 12})/2 and C{sub 44} which is ascribed to unusual vibration 'rattling' of Pr ions in an atomic cage formed by Sb-'icosahedron. On the other hand, the elastic constants C{sub 11} (C{sub 11}-C{sub 12})/2 and C{sub 44} increase monotonically with decreasing temperature in the case of RhSb{sub 3} and IrSb{sub 3}. No such a characteristic increase was observed. These results give us a piece of evidence that the guest ions would play a crucial role for 'rattling motion' in filled skutterudite compounds.

  2. Electrical and ferroelectric studies of the 2-layered SrBi{sub 2}Ta{sub 2}O{sub 9} based ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Swain, Sridevi [Department of Physics & Astronomy, National Institute of Technology, Rourkela 769008 (India); Kumar, Pawan, E-mail: pawankumar@nitrkl.ac.in [Department of Physics & Astronomy, National Institute of Technology, Rourkela 769008 (India); Choudhary, Ram Bilash [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India)

    2015-11-15

    SrBi{sub 2}Ta{sub 2}O{sub 9}/SBT, Sr{sub 0.8}Bi{sub 2.15}Ta{sub 2}O{sub 9}/SB{sub ex}T and SrBi{sub 2}(Ta{sub 0.925}W{sub 0.075}){sub 2}O{sub 9}/SBTW, 2-layered perovskite ferroelectric ceramic samples were prepared in single phase by solid-state reaction technique. Similar crystal structure was observed from the XRD study of the calcined powders of all the SBT based systems. Enhanced transition temperature (T{sub c}), dielectric constant (ε{sub r}) and ferroelectric properties were observed in both the SB{sub ex}T and SBTW ceramic samples compared to the pure SBT ceramic samples. The higher remnant polarization (P{sub r})~8.07 μC/cm{sup 2} and lower coercive field (E{sub c})~15.18 kV/cm were observed in the SB{sub ex}T ceramic samples. The bipolar fatigue study was carried out and the normalized polarization vs. number of cycles (up to 10{sup 9}) behavior confirmed the fatigue resistant nature of all the SBT based ceramic samples. In comparison to the pure SBT ceramic samples, decreased leakage current with increased piezoelectric properties were observed in both the SB{sub ex}T and SBTW ceramic samples.

  3. Metal–organic deposition of YBa2 Cu3 Ox and Bi2 Sr2 Ca1 Cu2 Ox ...

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. YBa2Cu3Ox (Y-123 ) and Bi2Sr2Ca1Cu2Ox (Bi-2212) films on various substrates have been prepared by Metal-Organic Deposition starting from different metallorganic fluorine-free compounds and using a very simple instrumentation. The processing conditions include a rapid pyrolysis step in air and.

  4. Potential Thermoelectric Performance from Optimization of Hole-Doped Bi_{2}Se_{3}

    Directory of Open Access Journals (Sweden)

    David Parker

    2011-10-01

    Full Text Available We present an analysis of the potential thermoelectric performance of hole-doped Bi_{2}Se_{3}, which is commonly considered to show inferior room temperature performance when compared to Bi_{2}Te_{3}. We find that if the lattice thermal conductivity can be reduced by nanostructuring techniques (as have been applied to Bi_{2}Te_{3} in Refs. [W. Xie, X. Tang, Y. Yan, Q. Zhang, and T. M. Tritt, Unique Nanostructures and Enhanced Thermoelectric Performance of Melt-Spun BiSbTe Alloys, Appl. Phys. Lett. 94, 102111 (2009; APPLAB0003-695110.1063/1.3097026B. Poudel et al., High-Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys, Science 320, 634 (2008.SCIEAS0036-807510.1126/science.1156446] the material may show optimized ZT values of unity or more in the 300–500 K temperature range and thus be suitable for cooling and moderate temperature waste heat recovery and thermoelectric solar cell applications. Central to this conclusion are the larger band gap and the relatively heavier valence bands of Bi_{2}Se_{3}.

  5. Multiferroic properties of the Y2BiFe5O12 garnet

    Science.gov (United States)

    Durán, A.; Ostos, C.; Arnache, O.; Siqueiros, J. M.; García-Guaderrama, M.

    2017-10-01

    Multiferroic properties are found in the Yttrium iron garnet (YIG) modified with Bi3+. The X-ray diffraction pattern shows that the Bi3+ ion is completely soluble up to one-third of the Y molar content forming the Y2BiFe5O12 compound as a single phase. Structural analysis did not show signals of other incipient non-centrosymmetric phases in the compound. However, the dielectric and polarization studies clearly exhibit a typical relaxor ferroelectric behavior at room temperature where the maxima of the broad permittivity peaks shift with frequency. The quadratic diffuseness coefficient obtained from the modified Curie-Weiss law suggests polar nanoregion switching in a broad temperature range. Using the Vogel-Fulcher relationship, the activation energy and freezing temperature were found to be 243.1 meV and 322.6 K, respectively. Here, the main contribution to relaxation comes from thermally activated reorientation of the dipole moments, as confirmed by the well-defined hysteresis loops in the P-E measurements. The dipole fluctuations arise from the compositional disorder induced by Bi3+ ions randomly distributed in the lattice, having thermally active polarization fluctuations above the freezing temperature, Tf. Furthermore, it is found that Bi3+ preserves the magnetization features of this compound. Thus, the Bi3+ modified YIG compound is found to be a multiferroic material at room temperature.

  6. Synthesis and structural characterisation of the new K2NiF4-type phases, A2In0.5Sb0.5O4 (A=Sr, Ba)

    OpenAIRE

    Heap, Richard; Islam, Saiful; Slater, Peter

    2004-01-01

    In this paper we report the synthesis and structural characterisation of two new K2NiF4-type phases, Ba2In0.5Sb0.5O4 and Sr2In0.5Sb0.5O4. To our knowledge these are the first examples of K2NiF4 compounds of general formula A2MIII0.5M'V0.5O4 with both 3+ and 5+ cations in the octahedral sites. Ba2In0.5Sb0.5O4 is shown to have a tetragonal cell (space group I4/mmm, a=4.1651(1), c=13.299(1) Å) with an essentially disordered arrangement of In and Sb. In the case of Sr2In0.5Sb0.5O4, however, order...

  7. Temperature-driven topological quantum phase transitions in a phase-change material Ge2Sb2Te5.

    Science.gov (United States)

    Eremeev, S V; Rusinov, I P; Echenique, P M; Chulkov, E V

    2016-12-13

    The Ge2Sb2Te5 is a phase-change material widely used in optical memory devices and is a leading candidate for next generation non-volatile random access memory devices which are key elements of various electronics and portable systems. Despite the compound is under intense investigation its electronic structure is currently not fully understood. The present work sheds new light on the electronic structure of the Ge2Sb2Te5 crystalline phases. We demonstrate by predicting from first-principles calculations that stable crystal structures of Ge2Sb2Te5 possess different topological quantum phases: a topological insulator phase is realized in low-temperature structure and Weyl semimetal phase is a characteristic of the high-temperature structure. Since the structural phase transitions are caused by the temperature the switching between different topologically non-trivial phases can be driven by variation of the temperature. The obtained results reveal the rich physics of the Ge2Sb2Te5 compound and open previously unexplored possibility for spintronics applications of this material, substantially expanding its application potential.

  8. Overexpression of SbMyb60 impacts phenylpropanoid biosynthesis and alters secondary cell wall composition in Sorghum bicolor.

    Science.gov (United States)

    Scully, Erin D; Gries, Tammy; Sarath, Gautam; Palmer, Nathan A; Baird, Lisa; Serapiglia, Michelle J; Dien, Bruce S; Boateng, Akwasi A; Ge, Zhengxiang; Funnell-Harris, Deanna L; Twigg, Paul; Clemente, Thomas E; Sattler, Scott E

    2016-02-01

    The phenylpropanoid biosynthetic pathway that generates lignin subunits represents a significant target for altering the abundance and composition of lignin. The global regulators of phenylpropanoid metabolism may include MYB transcription factors, whose expression levels have been correlated with changes in secondary cell wall composition and the levels of several other aromatic compounds, including anthocyanins and flavonoids. While transcription factors correlated with downregulation of the phenylpropanoid biosynthesis pathway have been identified in several grass species, few transcription factors linked to activation of this pathway have been identified in C4 grasses, some of which are being developed as dedicated bioenergy feedstocks. In this study we investigated the role of SbMyb60 in lignin biosynthesis in sorghum (Sorghum bicolor), which is a drought-tolerant, high-yielding biomass crop. Ectopic expression of this transcription factor in sorghum was associated with higher expression levels of genes involved in monolignol biosynthesis, and led to higher abundances of syringyl lignin, significant compositional changes to the lignin polymer and increased lignin concentration in biomass. Moreover, transgenic plants constitutively overexpressing SbMyb60 also displayed ectopic lignification in leaf midribs and elevated concentrations of soluble phenolic compounds in biomass. Results indicate that overexpression of SbMyb60 is associated with activation of monolignol biosynthesis in sorghum. SbMyb60 represents a target for modification of plant cell wall composition, with the potential to improve biomass for renewable uses. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  9. Bi-Cell Unit for Fuel Cell.

    Science.gov (United States)

    The patent concerns a bi-cell unit for a fuel cell . The bi-cell unit is comprised of two electrode packs. Each of the electrode packs includes an...invention relates in general to a bi-cell unit for a fuel cell and in particular, to a bi-cell unit for a hydrazine-air fuel cell .

  10. Higher critical current density achieved in Bi-2223 High-Tc superconductors

    Directory of Open Access Journals (Sweden)

    M.S. Shalaby

    2016-07-01

    Full Text Available Bi2Sr2Ca2Cu3Ox (Bi-2223 were prepared using a solid state reaction method at different sintering times and temperatures. Structural phase identifications have been done using X-Ray analysis and refinement by Reitveld method which proves the coexistence of Bi-2223 and Bi-2212 phases. The critical transition temperature Tc and critical current density Jc values were measured using superconducting quantum interference device magnetometer (SQUID and by the magneto-optics technique. A remarkable rapid decrease to the diamagnetic signal in the magnetization versus temperature M(T at 110 K and Jc around 1.2 × 107 A/m2 at 5 K are confirmed for the Bi-2223 compound.

  11. Electronic structure, ferroelectricity and optical properties of CaBi2Ta2O9

    Science.gov (United States)

    Xu, B.; Li, X.; Sun, J.; Yi, L.

    2008-12-01

    Using first-principles calculations based on density-functional theory in its local-density approximation, we investigated the Electronic structure, ferroelectricity and optical properties of CaBi2Ta2O9 (CBT) for the first time. It is found that CBT compound has an indirect band gap of 3.114 eV and the O 2s and 2p states are strongly hybridized with the 6s states of Bi which belong to the (Bi2O2)2+ planes. The quite strong Ta-O and Bi-O hybridization is the primary source for ferroelectricity. Our results imply that the interaction between Bi and O is highly covalent. The anisotropy occurs mainly above 4 eV in the optical properties. The different optical properties have been discussed.

  12. Synthesis of B–Sb by rapid thermal annealing of B/Sb multilayer films

    Indian Academy of Sciences (India)

    layer with predetermined thickness of boron and antimony and subsequently subjecting the multilayer to rapid thermal annealing. The films were characterized by measuring microstructural, optical and compositional properties. 2. Experimental. Multilayer films of B and Sb were deposited onto Si and fused silica substrates ...

  13. Strained InGaSb/AlGa(As)Sb Quantum Wells for p-Channel Transistors

    Science.gov (United States)

    Bennett, Brian R.; Podpirka, Adrian A.; Boos, J. B.; Kumar, Satvika L.

    2016-06-01

    Quantum wells of InGaSb clad by AlGa(As)Sb were grown by molecular beam epitaxy. Well and barrier compositions were chosen to yield biaxial compressive strain and enhanced hole mobility in the InGaSb. Wells with thickness of 7.5 nm exhibited room-temperature mobilities of 1000 cm2/V s to 1100 cm2/V s, with the surface-layer material influencing two-dimensional hole densities. The introduction of As into the barrier material allows a wider range of p-channel well/barrier combinations and lattice constants. These could be compatible with n-channel InGaAs wells for complementary field-effect transistor circuits which utilize a common buffer layer. InGaSb wells with thicknesses of 20 nm to 30 nm and compressive strains of 1.0% to 1.5% exhibited hole mobilities of 700 cm2/V s to 900 cm2/V s.

  14. Improved structural and electrical properties in native Sb2Te3/GexSb2Te3+x van der Waals superlattices due to intermixing mitigation

    NARCIS (Netherlands)

    Cecchi, Stefano; Zallo, Eugenio; Momand, Jamo; Wang, Ruining; Kooi, Bart J.; Verheijen, Marcel A.; Calarco, Raffaella

    Superlattices made of Sb2Te3/GeTe phase change materials have demonstrated outstanding performance with respect to GeSbTe alloys in memory applications. Recently, epitaxial Sb2Te3/GeTe superlattices were found to feature GexSb2Te3+x blocks as a result of intermixing between constituting layers.

  15. Structure and Thermoelectric Properties of Bi2−xSbxTe3 Nanowires Grown in Flexible Nanoporous Polycarbonate Templates

    Directory of Open Access Journals (Sweden)

    Anuja Datta

    2017-05-01

    Full Text Available We report the room-temperature growth of vertically aligned ternary Bi2−xSbxTe3 nanowires of diameter ~200 nm and length ~12 µm, within flexible track-etched nanoporous polycarbonate (PC templates via a one-step electrodeposition process. Bi2−xSbxTe3 nanowires with compositions spanning the entire range from pure Bi2Te3 (x = 0 to pure Sb2Te3 (x = 2 were systematically grown within the nanoporous channels of PC templates from a tartaric–nitric acid based electrolyte, at the end of which highly crystalline nanowires of uniform composition were obtained. Compositional analysis showed that the Sb concentration could be tuned by simply varying the electrolyte composition without any need for further annealing of the samples. Thermoelectric properties of the Bi2−xSbxTe3 nanowires were measured using a standardized bespoke setup while they were still embedded within the flexible PC templates.

  16. The highly enhanced visible light photocatalytic degradation of gaseous o-dichlorobenzene through fabricating like-flowers BiPO{sub 4}/BiOBr p-n heterojunction composites

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Xuejun [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Dong, Yuying, E-mail: dongy@dlnu.edu.cn [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Zhang, Xiaodong, E-mail: fatzhxd@126.com [Environment and Low-Carbon Research Center, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, 200093 (China); Cui, Yubo; Ou, Xiaoxia [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Qi, Xiaohui [College of Life Science, Dalian Nationalities University, Dalian, 116600 (China)

    2017-01-01

    Highlights: • Like-flowers BiPO{sub 4}/BiOBr was fabricated by mixing in solvent method. • o-Dichlorobenzene removal efficiency was 53.6% using BiPO{sub 4}/BiOBr. • The p–n junction improved o-dichlorobenzene degradation activity. - Abstract: In this paper, in order to enhance photo-induced electron-hole pairs separation of BiOBr, flowers-like BiPO{sub 4}/BiOBr p-n heterojunction composites was fabricated by a mixing in solvent method. The as-prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV–vis absorption spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and N{sub 2} adsorption-desorption. Meanwhile, their photocatalytic properties were investigated by the degradation of gaseous o-dichlorobenzene under visible light irradiation. Due to its strong adsorption capacity and the formation of p-n heterojunction, compared with BiPO{sub 4} and BiOBr, the BiPO{sub 4}/BiOBr composites showed higher photocatalytic activity in the degradation of gaseous o-DCB under visible light. Among them, 2% BiPO{sub 4}/BiOBr showed the maximum value of the activity, whose degradation rate was about 2.6 times as great as the pure BiOBr. Furthermore, the OH· was confirmed the main active species during the photocatalytic process by the trapping experiments. The outstanding performance indicated that the photocatalysts could be applied to air purification for chlorinated volatile organic compound.

  17. Features of high-temperature electroluminescence in an LED n-GaSb/n-InGaAsSb/p-AlGaAsSb heterostructure with high potential barriers

    Energy Technology Data Exchange (ETDEWEB)

    Danilov, L. V., E-mail: danleon84@mail.ru; Petukhov, A. A.; Mikhailova, M. P.; Zegrya, G. G.; Ivanov, E. V.; Yakovlev, Yu. P. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2016-06-15

    The electroluminescent properties of a light-emitting diode n-GaSb/n-InGaAsSb/p-AlGaAsSb heterostructure with high potential barriers are studied in the temperature range of 290–470 K. An atypical temperature increase in the power of the long-wavelength luminescence band with an energy of 0.3 eV is experimentally observed. As the temperature increases to 470 K, the optical radiation power increases by a factor of 1.5–2. To explain the extraordinary temperature dependence of the radiation power, the recombination and carrier transport processes are theoretically analyzed in the heterostructure under study.

  18. Electronic structure and thermoelectric properties of half-Heusler compounds with eight electron valence count—KScX (X = C and Ge)

    Energy Technology Data Exchange (ETDEWEB)

    Ciftci, Yasemin O. [Department of Physics, Gazi University, Teknikokullar, Ankara 06500 (Turkey); Mahanti, Subhendra D. [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)

    2016-04-14

    Electronic band structure and structural properties of two representative half-Heusler (HH) compounds with 8 electron valence count (VC), KScC and KScGe, have been studied using first principles methods within density functional theory and generalized gradient approximation. These systems differ from the well studied class of HH compounds like ZrNiSn and ZrCoSb which have VC = 18 because of the absence of d electrons of the transition metal atoms Ni and Co. Electronic transport properties such as Seebeck coefficient (S), electrical conductivity (σ), electronic thermal conductivity (κ{sub e}) (the latter two scaled by electronic relaxation time), and the power factor (S{sup 2}σ) have been calculated using semi-classical Boltzmann transport theory within constant relaxation time approximation. Both the compounds are direct band gap semiconductors with band extrema at the X point. Their electronic structures show a mixture of heavy and light bands near the valance band maximum and highly anisotropic conduction and valence bands near the band extrema, desirable features of good thermoelectric. Optimal p- or n-type doping concentrations have been estimated based on thermopower and maximum power factors. The optimum room temperature values of S are ∼1.5 times larger than that of the best room temperature thermoelectric Bi{sub 2}Te{sub 3}. We also discuss the impact of the band structure on deviations from Weidemann-Franz law as one tunes the chemical potential across the band gap.

  19. Bilinguismes ou bi- appartenances

    Directory of Open Access Journals (Sweden)

    Jean-Charles Vegliante

    2012-10-01

    Full Text Available Dans cet essai, l’auteur évoque son sentiment de bi-appartenance lorsqu’il séjourne à Sienne, une de ses villes de prédilection. A l’occasion d’un congrès sur le thème : « Repenser la Méditerranée », ou de la projection d’un film évoquant les lendemains de massacres, il soulève des questions existentielles, en particulier la nécessité de « se parler ». Le bilinguisme se définit selon l’auteur comme une nécessité, une volonté de mieux entendre l’autre. Il évoque les exemples des poètes italiens Giuseppe Ungaretti (parfaitement francophone et Gabriele D’Annunzio, de l’allemand Franz Kafka et de l’anglais Milton. L’auteur passe du français à l’italien : « Lost in translation ?», comme il le dit plaisamment en conclusion.

  20. Epitaxial growth of GaSb on V-grooved Si (001) substrates with an ultrathin GaAs stress relaxing layer

    Science.gov (United States)

    Li, Qiang; Lai, Billy; Lau, Kei May

    2017-10-01

    We report epitaxial growth of GaSb nano-ridge structures and planar thin films on V-groove patterned Si (001) substrates by leveraging the aspect ratio trapping technique. GaSb was deposited on {111} Si facets of the V-shaped trenches using metal-organic chemical vapor deposition with a 7 nm GaAs growth initiation layer. Transmission electron microscopy analysis reveals the critical role of the GaAs layer in providing a U-shaped surface for subsequent GaSb epitaxy. A network of misfit dislocations was uncovered at the GaSb/GaAs hetero-interface. We studied the evolution of the lattice relaxation as the growth progresses from closely pitched GaSb ridges to coalesced thin films using x-ray diffraction. The omega rocking curve full-width-at-half-maximum of the resultant GaSb thin film is among the lowest values reported by molecular beam epitaxy, substantiating the effectiveness of the defect necking mechanism. These results thus present promising opportunities for the heterogeneous integration of devices based on 6.1 Å family compound semiconductors.

  1. BiOBr/BiOI Photocatalyst Based on Fly Ash Cenospheres with Improved Photocatalytic Performance.

    Science.gov (United States)

    Lin, Li; Huang, Manhong; Chen, Donghui

    2016-05-19

    A series of BiOBr/BiOI photocatalysts supported on fly-ash cenospheres (FACs) were successfully prepared via a facile one-pot alcoholysis method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectrometer (XPS) and UV-visible diffuse reflectance spectroscopy (DRS). The results indicate that pH value plays a critical role in BiOBr/BiOI loading. Based on the photodegradation tests under visible light irradiation (blue LED irradiation), the photocatalytic property of BiOBr/BiOI/FACs photocatalysts obtained under alkaline conditions is superior to that prepared under neutral or acidic conditions, and higher than those of BiOB/FACs and BiOI//FACs. The improved photocatalytic performance of BiOBr/BiOI/FACs can be attributed to more BiOBr/BiOI loaded on the surface of FACs and the efficient photogenerated electron-hole separation.

  2. Specific heat and Hall effect of the ferromagnetic Kondo lattice UCu0.9Sb2

    Science.gov (United States)

    Tran, V. H.; Bukowski, Z.

    2017-06-01

    We have investigated the electrical resistivity ρ, specific heat C p and Hall coefficient R H on a single crystal of a ferromagnetic Kondo lattice UCu0.9Sb2. The experimental ρ (T) , C p (T) and {{R}\\text{H}}(T) data evidence a bulk magnetic phase transition at {{T}\\text{C}}=113 K, and additionally exhibit an unexpected bump located in the temperature range T C/10-T C/3. UCu0.9Sb2 has an enhanced electronic specific heat coefficient γ ˜ 71 mJ molK-2, corresponding to Kondo temperature {{T}\\text{K}}˜ 6.8 K. An analysis of the Hall effect data for j//(a, b)-plane and H// c-axis reveals that the low-temperature ordinary Hall coefficient R 0 is positive, suggesting that p-type electrical conductivity is dominant. The density of the carriers at 2 K is about 0.6 holes f.u.-1, which may categorize the studied compound into class of low carrier density compounds. Combined γ and R 0 data divulge an effective mass of charge carriers {{m}\\ast}˜ 27 m e . This finding together with quite low Hall mobility {μ\\text{H}}=25 cm2 Vs-1 and Kadowaki-Woods ratio {{r}\\text{KW}}=0.98× ~{{10}-5} μ Ω cm (mol K2 mJ-1)2, manifest the development of heavy-fermion state in the ferromagnetic UCu0.9Sb2 compound at low temperatures.

  3. Mid-IR InAsSb photovoltaic detectors

    Science.gov (United States)

    Rakovska, Anna; Berger, Vincent; Marcadet, Xavier; Glastre, Genevieve; Vinter, Borge; Bouzehouane, K.; Kaplan, Daniel; Oksehendler, T.

    2000-04-01

    We describe a mid-IR photovoltaic detector using InAsSb as active material, grown by MBE on a GaSb substrate. The purpose of this study is to show that quantum detectors can offer an alternative to thermal detectors for high temperature operation. With a 9 percent Sb content, InAsSb is lattice matched to GaSb and thus provides an excellent material quality, with Shokley-Read lifetimes of the order of 200 ns as measured by photoconductive gain measurements as well as time resolved photoconductivity experiments. The band gap of InAsSb corresponds to a wavelengths as well as time resolved photoconductivity experiments. The band gap of InAsSb corresponds to a wavelength of 5 microns at room temperature. This makes InAsSb an ideal candidate for rom temperature detection in the 3-5 microns atmospheric window. Photovoltaic structures are characterized by current voltage characteristics as a function of temperature. Using the absorption value obtained on the test samples, a detectivity of 7 by 109 Jones can be obtained at a temperature of 250 K, which can easily be reached with Peltier cooling. This leads to a NETD lower than 80 mK.

  4. Reduction of [Cp*Sb]4 with Subvalent Main-Group Metal Reductants: Syntheses and Structures of [(L1 Mg)4 (Sb4 )] and [(L2 Ga)2 (Sb4 )] Containing Edge-Missing Sb4 Units.

    Science.gov (United States)

    Ganesamoorthy, Chelladurai; Krüger, Julia; Wölper, Christoph; Nizovtsev, Anton S; Schulz, Stephan

    2017-02-16

    [Cp*Sb]4 (Cp*=C5 Me5 ) reacts with [L1 Mg]2 and L2 Ga with formation of [(L1 Mg)4 (μ4 ,η1:2:2:2 -Sb4 )] (L1 =iPr2 NC[N(2,6-iPr2 C6 H3 )]2 , 1) and [(L2 Ga)2 (μ,η2:2 -Sb4 )] (L2 =HC[C(Me)N(2,6-iPr2 C6 H3 )]2 , 2). The cleavage of the Sb-Sb and Sb-C bonds in [Cp*Sb]4 are the crucial steps in both reactions. The formation of 1 occurred by elimination of the Cp* anion and formation of Cp*MgL1 , while 2 was formed by reductive elimination of Cp*2 and oxidative addition of L2 Ga to the Sb4 unit. 1 and 2 were characterized by heteronuclear NMR spectroscopy and single-crystal X-ray diffraction, and their bonding situation was studied by quantum chemical calculations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. SULFURIC ACID CORROSION OF LOW Sb - Pb BATTERY ALLOYS

    African Journals Online (AJOL)

    user

    1 SEPTEMBER 1983 NTUKOGU. 42. SULFURIC ACID CORROSION OF LOW Sb - Pb BATTERY ALLOYS by. T. O. Ntukogu. Mechanical Engineering Department. University of Nigeria, Nsukka. (Manuscript received February,1983). ABSTRACT. The corrosion properties of low Sb - Pb alloys developed for maintenance free ...

  6. Undoped InSb radiation detector for radiation measurement

    CERN Document Server

    Hishiki, S; Sugiura, O; Murase, Y; Nakamura, T; Katagiri, M

    2003-01-01

    A Schottky type detector was fabricated with undoped InSb wafer. We could measure the energy of sup 2 sup 4 sup 1 Am alpha particles with this InSb detector at the operating temperature from 2 K to 65 K.

  7. Nanotubes from Misfit Layered Compounds: A New Family of Materials with Low Dimensionality.

    Science.gov (United States)

    Panchakarla, Leela S; Radovsky, Gal; Houben, Lothar; Popovitz-Biro, Ronit; Dunin-Borkowski, Rafal E; Tenne, Reshef

    2014-11-06

    Nanotubes that are formed from layered materials have emerged to be exciting one-dimensional materials in the last two decades due to their remarkable structures and properties. Misfit layered compounds (MLC) can be produced from alternating assemblies of two different molecular slabs with different periodicities with the general formula [(MX)1+x]m[TX2]n (or more simply MS-TS2), where M is Sn, Pb, Bi, Sb, rare earths, T is Sn, Nb, Ta, Ti, V, Cr, and so on, and X is S, Se. The presence of misfit stresses between adjacent layers in MLC provides a driving force for curling of the layers that acts in addition to the elimination of dangling bonds. The combination of these two independent forces leads to the synthesis of misfit layered nanotubes, which are newcomers to the broad field of one-dimensional nanostructures and nanotubes. The synthesis, characterization, and microscopic details of misfit layered nanotubes are discussed, and directions for future research are presented.

  8. Study on the Reliability of Carbon Nanotube-Reinforced Sn-58Bi Lead-Free Solder Joints

    Science.gov (United States)

    Yang, Li; Liu, Haixiang; Zhang, Yaocheng; Yu, Huakuan

    2017-10-01

    The wettability, microstructure and mechanical properties of multi-walled carbon nanotube (CNT)-reinforced Sn-58Bi composite solder joints were investigated. The results indicate that the wettability of the Sn-58Bi solder is improved and the growth of interfacial intermetallic (IMC) compounds for solder joints is restrained by CNTs. The thickness of the IMC layers is decreased with increasing CNTs concentration. The microstructure of the Sn-58Bi composite solders is refined, the maximum tensile strength and shear strength are obtained by adding the optimum CNTs content about 0.01 wt.%. However, excessive content of CNTs addition can deteriorate the properties. The creep rupture life of Sn-58Bi solder joint and Sn-58Bi-0.01CNTs solder joint is decreased with increasing load, temperature and current density. The average creep rupture life of Sn-58Bi-0.01CNTs composite solder joint is 60% higher than that of the plain solder joint.

  9. Indium doped BiOI nanosheets: Preparation, characterization and photocatalytic degradation activity

    Science.gov (United States)

    Li, Haibo; Yang, Zujin; Zhang, Jingnan; Huang, Yongchao; Ji, Hongbing; Tong, Yexiang

    2017-11-01

    Semiconductor photocatalysis is a promising method to remove the harmful compounds into harmless molecules. Herein, In-doped BiOI (In-BiOI) photocatalysts with highly exposed dominant {001} facets were synthesized through a facile hydrothermal method. The XRD, SEM and TEM determinations revealed the high crystallinity structure of the samples, and the XPS results confirmed the doping of In. The In-BiOI nanosheets exhibited a higher activity in the photodegradation of p-chloroaniline (PCA) than that of pristine BiOI, among which the In-2 BiOI sample (feed mole ratio of In:Bi = 2%) possessed the best performance. Doping with In didn't alter the structure, morphology, specific surface area or light absorption capacity of BiOI, but significantly improved its charge separation efficiency and transport capability, which were verified by the results of the lower PL emission, larger photocurrent intensity and smaller arc radius of EIS plots. More importantly, the mechanism of photocatalytic degradation is studied systematically, revealing that rad O2- and h+ were the major reactive species during the photodegradation process. Finally, the possible role of In-doping in enhancing the photocatalytic performance of BiOI is proposed.

  10. RuBi-Glutamate: Two-photon and visible-light photoactivation of neurons and dendritic spines

    Directory of Open Access Journals (Sweden)

    Elodie Fino

    2009-05-01

    Full Text Available We describe neurobiological applications of RuBi-Glutamate, a novel caged-glutamate compound based on ruthenium photochemistry. RuBi-Glutamate can be excited with visible wavelengths and releases glutamate after one- or two-photon excitation. It has high quantum efficiency and can be used at low concentrations, partly avoiding the blockade of GABAergic transmission present with other caged compounds. Two-photon uncaging of RuBi-glutamate has a high spatial resolution and generates excitatory responses in individual dendritic spines with physiological kinetics. With laser beam multiplexing, RuBi-Glutamate uncaging can also be used to depolarize and fire pyramidal neurons with single-cell resolution. RuBi-Glutamate therefore enables the photo-activation of neuronal dendrites and circuits with visible or two-photon light sources, achieving single spine, or single cell, precision.

  11. Structural and Thermoelectronic Properties of Chalcopyrite MgSiX2 (X = P, As, Sb)

    Science.gov (United States)

    Kocak, B.; Ciftci, Y. O.; Surucu, G.

    2017-01-01

    We have explored the structural, electronic, optical, and mechanical properties of the magnesium-based chalcopyrites MgSiP2, MgSiAs2, and MgSiSb2 using density functional theory with five different generalized gradient approximation (GGA) functionals: Perdew-Wang (1991), Perdew-Burke-Ernzerhof, revised Perdew-Burke-Ernzerhof, modified Perdew-Burke-Ernzerhof for solids, and Armiento-Mattson (2005) as well as the local density approximation. Change of the constituent element from P to Sb significantly affected the lattice constants, elastic constants, and thermal and dielectric properties. Our theoretically computed results are in reasonable agreement with experiments and other theoretical calculations. The electronic band structure results imply that all three considered compounds are semiconductors. MgSiP2 has the highest value of elastic constants, and bulk and shear moduli compared with the other two binary chalcopyrites. Furthermore, the optical response in terms of the dielectric functions, optical reflectivity, refractive index, extinction coefficient, and electron energy loss of the compounds were also investigated in the energy range from 0 eV to 15 eV. The calculated optical results reveal optical polarization anisotropy for all three compounds, making them useful for optoelectronic device applications. Moreover, specific focus is also given to quantify the dependence of various thermal properties on finite pressure/temperature within the quasiharmonic approximation.

  12. Structure and magnetic interactions in (Sr, Sb)-doped lanthanum manganites

    Energy Technology Data Exchange (ETDEWEB)

    Karpinsky, D.V., E-mail: karpinsky@physics.by [National Research University of Electronic Technology “MIET”, 124498 Moscow, Zelenograd (Russian Federation); Scientific-Practical Materials Research Centre of NAS of Belarus, 220072 Minsk (Belarus); Troyanchuk, I.O.; Silibin, M.V.; Gavrilov, S.A. [National Research University of Electronic Technology “MIET”, 124498 Moscow, Zelenograd (Russian Federation); Bushinky, M.V. [Scientific-Practical Materials Research Centre of NAS of Belarus, 220072 Minsk (Belarus); Sikolenko, V. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Frontzek, M. [Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, 5232 Villigen (Switzerland)

    2016-05-15

    Ceramic samples La{sub 1−2x}Sr{sub 2x}Mn{sub 1−x}Sb{sub x}O{sub 3} (x≤0.2) have been studied by X-ray and neutron powder diffraction, magnetization measurements and charge density calculations have also been performed. The compounds are characterized by the rhombohedral structure at room temperature; temperature decrease causes structural transition to the orthorhombic structure. La{sub 1−2x}Sr{sub 2x}Mn{sub 1−x}Sb{sub x}O{sub 3} ceramics are characterized by homovalent manganese ions and have long range ferromagnetic order which gradually diminishes with the chemical substitution. It is considered that magnetic properties of the compounds are determined by the dominance of ferromagnetic superexchange interactions stabilized in the orbital disordered orthorhombic phase. Significant covalent component of the Mn–O chemical bonds contributes to the long-range ferromagnetic order of the compounds, the covalency of the chemical bonds is assumed to be isotropically distributed over the orthorhombic phase.

  13. Structural characterization of [(μ-H)Os 3(CO) 10(μ-NH 2)] and a new polymorphic form of [(μ-H)Os 3(CO) 10(μ-SH)]. Influence of the bridging group on the geometry of compounds [(μ-H)Os 3(CO) 10(μ-X)] (X = NH 2, NRH, PRH, SbR 2, OH, SH, SR, SeR, Cl, Br). Reactions of [(μ-H)Os 3(CO) 10(μ-X)] (X = OH and SH) with proton sponge

    Science.gov (United States)

    Reyes-López, Ottmar R.; Leyva, Marco A.; Rosales-Hoz, María J.

    2011-01-01

    Compounds [(μ-H)Os 3(CO) 10(μ-NH 2)] and a new polymorphic form of [(μ-H)Os 3(CO) 10(μ-SH)] were obtained from the reaction of [H 2Os 3(CO) 10] with 1,3,5-N,N,N,-trimethyl-triazinane and 1,3,5-trithiane respectively. The structures show the same geometry described for other doubly bridged triangular clusters. A comparison of these type of compounds show that the bridging group does not affect significantly the dihedral angle between Os 3 and Os 2X planes (X = NH 2, NRH, PRH, SbR 2, OH, OR, SH, SR, SeR, Cl and Br). The presence of a hydrogen atom on the bridge could favor a possible interaction between groups so the crystal packing is analyzed. Since intermolecular interactions could also be occurring in solution, reactions of [(μ-H)Os 3(CO) 10(μ-OH)] and [(μ-H)Os 3(CO) 10(μ-SH)] with proton sponge were carried out in order to determine if the OH or SH protons had acidic character and could react with a base. These results and other structural characteristics will be discussed.

  14. Effects of Y, Nd and Sb on microstructure of Mg-6Al alloy

    Science.gov (United States)

    Li, Ke-jie

    2017-09-01

    Effects of Y, Nd and Sb on the microstructure of Mg-6Al magnesium alloy were investigated by optical microscope, SEM, EDS, XRD and TEM. The results showed that, with the increase of Sb content from 0.5% to 2.0wt%, the formation of Sb3Y5 (at 1.0% Sb) or YSb (at 2.0% Sb) phase is observed. Sb3Y5 nano-phase and dispersed Al2Y, SbY phases are found in the alloy when the content of Sb reaches 2.0%.

  15. Preparation and characterization of Bi2S3 compound semiconductor

    Indian Academy of Sciences (India)

    orthorhombic phase with calculated lattice constant a = 11.14 Å, b = 11.30 Å and c = 3.96 Å. Scanning electron microscopy (SEM) pictures indicate the presence of layer lines on the surface of crystals thereby proving that these crystals are grown by layer by layer mechanism. We studied the transport properties viz.

  16. Quantum mechanical computation of structural, electronic, and thermoelectric properties of AgSbSe2

    Directory of Open Access Journals (Sweden)

    M Salimi

    2015-07-01

    Full Text Available In this work, density functional calculations and Boltzmann semiclassical theory of transport are used to investigate structural, electronic, and thermoelectric properties of AgSbSe2 crystal. According to the published experimental measurements, five more likely structures of this compound are considered and their structural and electronic properties are calculated and compared together. Then, thermoelectric properties (electrical conductivity, electronic contribution to the thermal conductivity, power factor, and Seebeck coefficient of three more stable structures are investigated in the constant relaxation time approximation. Finally, the calculated temperature dependence of Seebeck coefficient is compared with the corresponding experimental measurements of others.

  17. Characterization of Cr-doped Sb{sub 2}Te{sub 3} films and their application to phase-change memory

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qing; Xia, Yangyang; Zheng, Yonghui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); University of the Chinese Academy of Sciences, Beijing, 100049 (China); Shanghai Key Laboratory of Nanofabrication Technology for Memory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Liu, Bo; Zhu, Min; Song, Sannian; Lv, Shilong; Cheng, Yan; Song, Zhitang; Feng, Songlin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Shanghai Key Laboratory of Nanofabrication Technology for Memory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Huo, Ruru [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Shanghai Key Laboratory of Nanofabrication Technology for Memory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050 (China); Shanghaitech University, Shanghai, 200031 (China)

    2015-08-15

    Phase-change memory (PCM) is regarded as one of the most promising candidates for the next-generation nonvolatile memory. Its storage medium, phase-change material, has attracted continuous exploration. Along the traditional GeTe-Sb{sub 2}Te{sub 3} tie line, the binary compound Sb{sub 2}Te{sub 3} is a high-speed phase-change material matrix. However, the low crystallization temperature prevents its practical application in PCM. Here, Cr is doped into Sb{sub 2}Te{sub 3}, called Cr-Sb{sub 2}Te{sub 3} (CST), to improve the thermal stability. We find that, with increase of the Cr concentration, grains are obviously refined. However, all the CST films exhibit a single hexagonal phase as Sb{sub 2}Te{sub 3} without phase separation. Also, the Cr helps to inhibit oxidation of Sb atoms. For the selected film CST{sub 1}0.5, the resistance ratio between amorphous and crystalline states is more than two orders of magnitude; the temperature for 10-year data retention is 120.8 C, which indicates better thermal stability than GST and pure Sb{sub 2}Te{sub 3}. PCM cells based on CST{sub 1}0.5 present small threshold current/voltage (4 μA/0.67 V). In addition, the cell can be operated by a low SET/RESET voltage pulse (1.1 V/2.4 V) with 50 ns width. Thus, Cr-Sb{sub 2}Te{sub 3} with suitable composition is a promising novel phase-change material used for PCM with high speed and good thermal stability performances. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Antimony (Sb) and arsenic (As) in Sb mining impacted paddy soil from Xikuangshan, China: differences in mechanisms controlling soil sequestration and uptake in rice.

    Science.gov (United States)

    Okkenhaug, Gudny; Zhu, Yong-Guan; He, Junwen; Li, Xi; Luo, Lei; Mulder, Jan

    2012-03-20

    Foods produced on soils impacted by antimony (Sb) mining activities are a potential health risk due to plant uptake of the contaminant metalloids (Sb) and arsenic (As). Here we report for the first time the chemical speciation of Sb in soil and porewater of flooded paddy soil, impacted by active Sb mining, and its effect on uptake and speciation in rice plants (Oryza sativa L. cv Jiahua). Results are compared with behavior and uptake of As. Pot experiments were conducted under controlled conditions in a climate chamber over a period of 50 days. In pots without rice plants, flooding increased both the concentration of dissolved Sb (up to ca. 2000 μg L(-1)) and As (up to ca. 1500 μg L(-1)). When rice was present, Fe plaque developing on rice roots acted as a scavenger for both As and Sb, whereby the concentration of As, but not Sb, in porewater decreased substantially. Dissolved Sb in porewater, which occurred mainly as Sb(V), correlated with Ca, indicating a solubility governed by Ca antimonate. No significant differences in bioaccumulation factor and translocation factor between Sb and As were observed. Greater relative concentration of Sb(V) was found in rice shoots compared to rice root and porewater, indicating either a preferred uptake of Sb(V) or possibly an oxidation of Sb(III) to Sb(V) in shoots. Adding soil amendments (olivine, hematite) to the paddy soil had no effect on Sb and As concentrations in porewater.

  19. Electronic structure and thermoelectricity of filled skutterudite CeRu{sub 4}Sb{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Shankar, A., E-mail: amitshan2009@gmail.com [Department of Physics, University of North Bengal, Darjeeling, 734013 (India); Rai, D.P. [Department of Physics, Pachhunga University College, Aizawl, 796001 (India); Sandeep [Condensed Matter Theory Research Group, Department of Physics, Mizoram University, Aizawl, 796004 (India); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, 29000 (Algeria); Thapa, R.K. [Condensed Matter Theory Research Group, Department of Physics, Mizoram University, Aizawl, 796004 (India); Mandal, P.K. [Department of Physics, University of North Bengal, Darjeeling, 734013 (India)

    2016-07-05

    First-principles calculations of the energy band structure and density of states of filled skutterudite CeRu{sub 4}Sb{sub 12} have been performed to understand the origin of thermoelectricity. The calculations are carried out using the full potential linear augmented plane wave (FP-LAPW) method within a framework of LDA approach. CeRu{sub 4}Sb{sub 12} is a metal with bands crossing Fermi energy level more than twice with indirect energy band gap of ∼0.09 eV above the Fermi energy level. The study of the elastic properties suggests the ductile nature of the material with covalent contribution in the atomic bonding. Our calculations performed for the density of electronic states near the Fermi energy level show that the large thermo-power at room temperature originates from the hybridized Ru-d and Sb-p orbitals. The study of the thermal transport properties suggests the high value of Seebeck coefficient with figure of merit (ZT) = 0.12, which is consistent to the values obtained for the analogous compounds. - Highlights: • CeRu{sub 4}Sb{sub 12} is ductile material with covalent contribution in bonding. • An indirect energy bandgap of 0.09 eV is present above the Fermi energy level. • The crossing of E{sub F} by the energy bands increases the number of DOS at E{sub F}. • Fermi level is situated within the valence region. • The thermal efficiency of the material is 0.12 at room temperature.

  20. Effects of pressure and strain on spin polarization of IrMnSb

    Science.gov (United States)

    Tutic, Ibrica; Herran, Juliana; Staten, Bradley; Gray, Paul; Paudel, Tula R.; Sokolov, Andrei; Tsymbal, Evgeny Y.; Lukashev, Pavel V.

    2017-02-01

    A high degree of spin polarization in electron transport is one of the most sought-after properties of a material which can be used in spintronics—an emerging technology utilizing a spin degree of freedom in electronic devices. An ideal candidate to exhibit highly spin-polarized current would be a room temperature half-metal, a material which behaves as an insulator for one spin channel and as a conductor for the other spin channel. In this paper, we explore a semi-Heusler compound, IrMnSb, which has been reported to exhibit pressure induced half-metallic transition. We confirm that the bulk IrMnSb is a spin-polarized metal, with dominant contribution to electronic states at the Fermi energy from majority-spin electrons. Application of a uniform pressure shifts the Fermi level into the minority-spin energy gap, thus demonstrating pressure induced half-metallic transition. This behavior is explained by the reduction of the exchange splitting of the spin bands consistent with the Stoner model for itinerant magnetism. We find that the half-metallic transition is suppressed when instead of uniform pressure the bulk IrMnSb is exposed to biaxial strain. This suppression of half-metallicity is driven by the epitaxial strain induced tetragonal distortion, which lifts the degeneracy of the Mn 3d t 2g and e g orbitals and reduces the minority-spin band gap under compressive strain, thus preventing half-metallic transition. Our calculations also indicate that in thin film geometry, surface states emerge in the minority-spin band gap, which has detrimental for practical applications impact on the spin polarization of IrMnSb.

  1. Rare-earth atom motions in ROs{sub 4}Sb{sub 12} (R = La, Pr, Nd, Sm)

    Energy Technology Data Exchange (ETDEWEB)

    Tsutsui, S; Uchiyama, H; Sutter, J P; Baron, A Q R [Japan Synchrotron Radiation Research Institute, SPring-8, Sayo, Hyogo 679-5198 (Japan); Sugawara, H [Graduate School of Integrated Arts and Sciences, the University of Tokushima, Tokushima, Tokushima 770-8502 (Japan); Yamaura, J; Hiroi, Z [Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 (Japan); Ochiai, A; Sato, H, E-mail: satoshi@spring8.or.j [Center for Low Temperature Science, Tohoku University, Sendai, Miyagi 980-8578 (Japan)

    2010-01-15

    High-resolution inelastic x-ray scattering (IXS) was carried out in the filled-skutterudites ROs{sub 4}Sb{sub 12} (R = La, Pr, Nd, Sm). Low-energy rare-earth modes were found in these compounds. They show significant rare-earth dependence, suggesting a correlation with lanthanide contraction. We discuss the relation between the present IXS measurements and reported other experiments.

  2. Tailoring the Composition and Properties of Sprayed CuSbS2 Thin Films by Using Polymeric Additives

    Directory of Open Access Journals (Sweden)

    Ionut Popovici

    2012-01-01

    Full Text Available CuSbS2 thin films were obtained by spray pyrolysis deposition, using polymeric additives for controlling the surface properties and film’s composition. Ternary crystalline chalcostibite compounds have been obtained without any postdeposition treatments. XRD spectra and IR spectroscopy were used to characterize films composition and interactions between components. Films morphology and surface energy were investigated using AFM microscopy and contact angle measurements. Hydrophobic and hydrophilic polymers strongly influence the composition and film morphology.

  3. Un nouvel oxyde naturel de Au et Sb

    Science.gov (United States)

    Johan, Zdenek; Šrein, Vladimir

    1998-04-01

    A gold-antimony X-ray amorphous oxide, resulting from a hydrothermal alteration of aurostibite, AuSb 2, occurs in the Krásná Hora gold deposit, Czech Republic. Its reflectivity is close to that of goethite. The average composition obtained by electron microprobe analyses (wt. %) is: Au - 68.32; Cu - 0.10; Sb - 21.26; As - 0.30; Si - 0.21; O - 8.44; total 98.63. This yields the empirical formula (Au 0.677Cu 0.003Sb 0.341As 0.008) 1.029O. The[(Au + Cu)/(Sb + As)] at ratio varies from 1.86 to 1.95. Among possible formulae satisfying the equilibrium of charges, that implying unique valence states for Au and/or Sb was retained. It can be written Au 1+2Sb 3+O 2(OH) with the theoretical composition (wt, %): Au - 69.76; Sb - 21.54; O - 8.50; H - 0.20. This Au- and Sb-bearing oxide is associated with native gold, electrum, aurostibite, arsenopyrite and pyrite in a quartz gangue. The powder pattern of AuSbO 3 was indexedon an orthorhombic unit-cell with a = 5.00(2); b = 12.46(4); c = 5.43(2) Å, Z = 4, Q calc = 7.20 g.cm 3, assuming a replacement of Sb 3+ by Au 3+ in the valentinite-type crystal structure.

  4. Electrodeposition and electrochemical characterisation of thick and thin coatings of Sb and Sb/Sb{sub 2}O{sub 3} particles for Li-ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Bryngelsson, Hanna; Eskhult, Jonas; Edstroem, Kristina; Nyholm, Leif [Department of Materials Chemistry, The Aangstroem Laboratory, Uppsala University, P.O. Box 538, SE-751 21 Uppsala (Sweden)

    2007-12-20

    The possibilities to electrodeposit thick coatings composed of nanoparticles of Sb and Sb{sub 2}O{sub 3} for use as high-capacity anode materials in Li-ion batteries have been investigated. It is demonstrated that the stability of the coatings depends on their Sb{sub 2}O{sub 3} concentrations as well as microstructure. The electrodeposition reactions in electrolytes with different pH and buffer capacities were studied using chronopotentiometry and electrochemical quartz crystal microbalance measurements. The obtained deposits, which were characterised with XRD and SEM, were also tested as anode materials in Li-ion batteries. The influence of the pH and buffer capacity of the deposition solution on the composition and particle size of the deposits were studied and it is concluded that depositions from a poorly buffered solution of antimony-tartrate give rise to good anode materials due to the inclusion of precipitated Sb{sub 2}O{sub 3} nanoparticles in the Sb coatings. Depositions under conditions yielding pure Sb coatings give rise to deposits composed of large crystalline particles with poor anode stabilities. The presence of a plateau at about 0.8 V versus Li{sup +}/Li due to SEI forming reactions and the origin of another plateau at about 0.4 V versus Li{sup +}/Li seen during the lithiation of thin Sb coatings are also discussed. It is demonstrated that the 0.4 V plateau is present for Sb coatings for which the (0 1 2) peak is the main peak in the XRD diffractogram. (author)

  5. Extrinsic doping of the half-Heusler compounds.

    Science.gov (United States)

    Stern, Robin; Dongre, Bonny; Madsen, Georg K H

    2016-08-19

    Controlling the p- and n-type doping is a key tool to improve the power-factor of thermoelectric materials. In the present work we provide a detailed understanding of the defect thermochemistry in half-Heusler compounds. We calculate the formation energies of intrinsic and extrinsic defects in state of the art n-type TiNiSn and p-type TiCoSb thermoelectric materials. It is shown how the incorporation of online repositories can reduce the workload in these calculations. In TiNiSn we find that Ni- and Ti-interstitial defects play a crucial role in the carrier concentration of TiNiSn. Furthermore, we find that extrinsic doping with Sb can substantially enhance the carrier concentration, in agreement with experiment. In case of TiCoSb, we find ScTi, FeCo and SnSb being possible p-type dopants. While experimental work has mainly focussed on Sn-doping of the Sb site, the present result underlines the possibility to p-dope TiCoSb on all lattice sites.

  6. Auger recombination in {GaSb}/{AlSb} multi quantum well heterostructures

    Science.gov (United States)

    Zielinski, E.; Schweizer, H.; Griffiths, G.; Kroemer, H.; Subbanna, S.

    The experimental determination of Auger coefficients in {GaSb}/{AlSb} multi quantum well heterostructures is reported for the first time. The luminescence at E g and E g+ Δ0, recorded under the same experimental conditions, is used to monitor the carrier recombination channels. A quantitative determination of the recombination coefficients is achieved applying coupled carrier rate equations for the conduction and the valence subbands including the split-off valence band. Information on the actual carrier density is obtained by line shape analysis of the E g-emission. Two dimensional carrier densities up to 10 12cm -2 are determined. Auger coefficients exhibit a pronounced well width dependence: above 100Å C ˜- 4·10 -27s -1cm 6 whereas at 50Å values are 10 times smaller. No resonance of the Auger recombination is observed tuning the band gap energy over the spin-orbit splitting with temperature.

  7. Structural, mechanical, electronic and magnetic properties of a new series of quaternary Heusler alloys CoFeMnZ (Z=Si, As, Sb): A first-principle study

    Energy Technology Data Exchange (ETDEWEB)

    Elahmar, M.H.; Rached, H.; Rached, D. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences, Université Djillali Liabès de SidiBel-Abbès, SidiBel-Abbès 22000 (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria); Murtaza, G. [Materials Modeling Lab, Department of Physics, Islamia College Peshawar, KPK (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Ahmed, W.K. [ERU, College of Engineering, United Arab Emirates University, Al Ain, Abu Dhabi (United Arab Emirates)

    2015-11-01

    The structural, mechanical, electronic and magnetic properties of the series of Heusler alloys CoFeMnZ (Z=Si, As, and Sb) have been investigated theoretically. The objective is to seek for stable half-metallic ferromagnets materials with Curie temperatures higher than room temperature. The series of CoFeMnZ (Z=Si, As and Sb) is found to exhibit half-metallic ferromagnetism with high magnetic moment and the localized moment in these magnetic compounds resides at the Mn atom. It has been observed that all our compounds have high Curie temperatures with high spin polarizations. - Highlights: • Density functional calculations for CoFeMnZ (Z=Si, As, Sb) compounds are performed. • Half-metallic ferromagnetism in CoFeMnZ (Z=Si, As, Sb) compounds is established. • The magnetic and mechanical properties for CoFeMnZ (Z=As, Sb) are studied for the first time. • The studied compounds possess high Curie temperatures with high spin polarizations.

  8. Effects of the selective 5-HT(7) receptor antagonist SB-269970 in animal models of psychosis and cognition.

    Science.gov (United States)

    Waters, Kerry A; Stean, Tania O; Hammond, Beverley; Virley, David J; Upton, Neil; Kew, James N C; Hussain, Ishrut

    2012-03-01

    The 5-hydroxytryptamine7 (5-HT7) receptor is a G-protein coupled receptor for serotonin that has been implicated in the pathophysiology of psychiatric and neurological disorders including anxiety, depression and schizophrenia. A number of studies have attempted to evaluate the potential role of the 5-HT7 receptor in schizophrenia by utilising genetic or pharmacological tools but to date these have provided conflicting results. Here we investigate the effect of a selective 5-HT7 receptor antagonist, SB-269970, in in vivo psychosis and cognition models and relate efficacy to brain exposures of the compound. SB-269970 significantly attenuated amphetamine-induced rearing and circling in rats. A similar effect was observed in an N-methyl d-aspartic acid (NMDA) receptor antagonist driven psychosis model, where SB-269970 significantly reversed phencyclidine-induced hyperlocomotion, rearing and circling; although the effect was not as robust as with the 5-HT2a receptor antagonist positive control, MDL100,907. SB-269970 also attenuated a temporal deficit in novel object recognition (NOR), indicative of an improvement in recognition memory. Pharmacokinetic analysis of plasma and brain samples taken after behavioural testing confirmed that efficacy was achieved at doses and pre-treatment times where receptor occupancy was substantial. These findings highlight the anti-psychotic and pro-cognitive potential of 5-HT7 receptor antagonists and warrant further studies to explore their therapeutic potential in schizophrenia. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Unusual crystallization behavior in Ga-Sb phase change alloys

    Directory of Open Access Journals (Sweden)

    Magali Putero

    2013-12-01

    Full Text Available Combined in situ X-ray scattering techniques using synchrotron radiation were applied to investigate the crystallization behavior of Sb-rich Ga-Sb alloys. Measurements of the sheet resistance during heating indicated a reduced crystallization temperature with increased Sb content, which was confirmed by in situ X-ray diffraction. The electrical contrast increased with increasing Sb content and the resistivities in both the amorphous and crystalline phases decreased. It was found that by tuning the composition between Ga:Sb = 9:91 (in at.% and Ga:Sb = 45:55, the change in mass density upon crystallization changes from an increase in mass density which is typical for most phase change materials to a decrease in mass density. At the composition of Ga:Sb = 30:70, no mass density change is observed which should be very beneficial for phase change random access memory (PCRAM applications where a change in mass density during cycling is assumed to cause void formation and PCRAM device failure.

  10. SbSI Nanosensors: from Gel to Single Nanowire Devices.

    Science.gov (United States)

    Mistewicz, Krystian; Nowak, Marian; Paszkiewicz, Regina; Guiseppi-Elie, Anthony

    2017-12-01

    The gas-sensing properties of antimony sulfoiodide (SbSI) nanosensors have been tested for humidity and carbon dioxide in nitrogen. The presented low-power SbSI nanosensors have operated at relatively low temperature and have not required heating system for recovery. Functionality of sonochemically prepared SbSI nanosensors made of xerogel as well as single nanowires has been compared. In the latter case, small amount of SbSI nanowires has been aligned in electric field and bonded ultrasonically to Au microelectrodes. The current and photocurrent responses of SbSI nanosensors have been investigated as function of relative humidity. Mechanism of light-induced desorption of H2O from SbSI nanowires' surface has been discussed. SbSI nanosensors have been tested for concentrations from 51 to 10(6) ppm of CO2 in N2, exhibiting a low detection limit of 40(31) ppm. The current response sensitivity has shown a tendency to decrease with increasing CO2 concentration. The experimental results have been explained taking into account proton-transfer process and Grotthuss' chain reaction, as well as electronic theory of adsorption and catalysis on semiconductors.

  11. SbSI Nanosensors: from Gel to Single Nanowire Devices

    Science.gov (United States)

    Mistewicz, Krystian; Nowak, Marian; Paszkiewicz, Regina; Guiseppi-Elie, Anthony

    2017-02-01

    The gas-sensing properties of antimony sulfoiodide (SbSI) nanosensors have been tested for humidity and carbon dioxide in nitrogen. The presented low-power SbSI nanosensors have operated at relatively low temperature and have not required heating system for recovery. Functionality of sonochemically prepared SbSI nanosensors made of xerogel as well as single nanowires has been compared. In the latter case, small amount of SbSI nanowires has been aligned in electric field and bonded ultrasonically to Au microelectrodes. The current and photocurrent responses of SbSI nanosensors have been investigated as function of relative humidity. Mechanism of light-induced desorption of H2O from SbSI nanowires' surface has been discussed. SbSI nanosensors have been tested for concentrations from 51 to 106 ppm of CO2 in N2, exhibiting a low detection limit of 40(31) ppm. The current response sensitivity has shown a tendency to decrease with increasing CO2 concentration. The experimental results have been explained taking into account proton-transfer process and Grotthuss' chain reaction, as well as electronic theory of adsorption and catalysis on semiconductors.

  12. Detailed DFT studies of the electronic structure and optical properties of KBaMSe{sub 3} (M = As, Sb)

    Energy Technology Data Exchange (ETDEWEB)

    Azam, Sikander; Khan, Saleem Ayaz; Khan, Wilayat [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Muhammad, Saleh; Udin, Haleem [Materials Modeling Lab, Department of Physics, Hazara University, Mansehra (Pakistan); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Laboratory, Department of Physics, Islamia College University, Peshawar (Pakistan); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria); Shah, Fahad Ali [Materials Modeling Lab, Department of Physics, Hazara University, Mansehra (Pakistan); Minar, Jan [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Ahmed, W.K. [ERU, College of Engineering, United Arab Emirates University, Al Ain (United Arab Emirates)

    2015-09-25

    Highlights: • The compounds are studied by FP-LAPW method within LDA, GGA, EV-GGA approximations. • All the compounds show indirect band gap nature. • Bonding nature is mixed covalent and ionic. • High absorption peaks and reflectivity ensures there utility in optoelectronic devices. - Abstract: Bonding nature as well as the electronic band structure, electronic charge density and optical properties of KBaMSe{sub 3} (M = As, Sb) compounds have been calculated using a full-potential augmented plane wave (FP-LAPW) method within the density functional theory. The exchange–correlation potential was handled with LDA and PBE-GGA approximations. Moreover, the Engel–Vosko generalized gradient approximation (EV-GGA) and the modified Beck–Johnson potential (mBJ) were also applied to improve the electronic band structure calculations. The study of band structure shows that KBaAsSe{sub 3}/KBaSbSe{sub 3} compounds have an indirect band gap of 2.08/2.10 eV which are in close agreement with the experimental data. The bonding nature has been studied as well using the electronic charge density (ECD) contour in the (1 0 1) crystallographic plane. It has been revealed that As/Sb–O atoms forms a strong covalent, while Ba–Se atoms form weak covalent bonding and the ionic bonding is mainly found between K and Ba atoms. Moreover, the complex dielectric function, absorption coefficient, refractive index, energy-loss spectrum and reflectivity have been estimated. From the reflectivity spectra, we found that KBaAsSe{sub 3} compound shows greater reflectivity than KBaSbSe{sub 3}, which means that KBaAsSe{sub 3} compound can be used as shielding material in visible and also in ultra violet region.

  13. Bandgap engineering of lead-free double perovskite Cs{sub 2}AgBiBr{sub 6} through trivalent metal alloying

    Energy Technology Data Exchange (ETDEWEB)

    Du, Ke-zhao; Mitzi, David B. [Department of Mechanical Engineering and Materials Science, and Department of Chemistry, Duke University, Durham, NC (United States); Meng, Weiwei; Wang, Xiaoming; Yan, Yanfa [Department of Physics and Astronomy and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, OH (United States)

    2017-07-03

    The double perovskite family, A{sub 2}M{sup I}M{sup III}X{sub 6}, is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH{sub 3}NH{sub 3}PbI{sub 3}. Given the generally large indirect band gap within most known double perovskites, band-gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs{sub 2}AgBiBr{sub 6} as host, band-gap engineering through alloying of In{sup III}/Sb{sup III} has been demonstrated in the current work. Cs{sub 2}Ag(Bi{sub 1-x}M{sub x})Br{sub 6} (M=In, Sb) accommodates up to 75 % In{sup III} with increased band gap, and up to 37.5 % Sb{sup III} with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs{sub 2}Ag(Bi{sub 0.625}Sb{sub 0.375})Br{sub 6}. Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Towards Next Generation BI Systems

    DEFF Research Database (Denmark)

    Varga, Jovan; Romero, Oscar; Pedersen, Torben Bach

    2014-01-01

    Next generation Business Intelligence (BI) systems require integration of heterogeneous data sources and a strong user-centric orientation. Both needs entail machine-processable metadata to enable automation and allow end users to gain access to relevant data for their decision making processes....... Although evidently needed, there is no clear picture about the necessary metadata artifacts, especially considering user support requirements. Therefore, we propose a comprehensive metadata framework to support the user assistance activities and their automation in the context of next generation BI systems...

  15. Modelling And Manufacturing GaSb TPV Converters

    Science.gov (United States)

    Algora, Carlos; Martín, Diego

    2003-01-01

    A complete model for GaSb TPV converters considering multiple real conditions (spectra, temperature, ARC, size, number and characteristics of grid fingers, size of busbar, etc.) is presented. The model has been applied to GaSb TPV converters fabricated in our laboratory by single zinc diffusion. The agreement between theory and experiments is very good. Future guides of performance improvement like the passivation of the surface together with the correspondent structure optimisation and the achievement of a better GaSb quality available more widespread are suggested.

  16. Synthesis, crystal structure, and magnetic properties of novel 2D kagome materials RE{sub 3}Sb{sub 3}Mg{sub 2}O{sub 14} (RE = La, Pr, Sm, Eu, Tb, Ho): Comparison to RE{sub 3}Sb{sub 3}Zn{sub 2}O{sub 14} family

    Energy Technology Data Exchange (ETDEWEB)

    Sanders, M.B.; Baroudi, K.M.; Krizan, J.W.; Mukadam, O.A.; Cava, R.J. [Department of Chemistry, Princeton University, Princeton, NJ (United States)

    2016-10-15

    The crystal structures and magnetic properties of RE{sub 3}Sb{sub 3}Mg{sub 2}O{sub 14} (RE = La, Pr, Sm, Eu, Tb, Ho) with a perfect kagome lattice are presented and compared to RE{sub 3}Sb{sub 3}Zn{sub 2}O{sub 14}. Rietveld structure refinements were performed using X-ray diffraction data, indicating that the layered compounds are fully structurally ordered. The compounds crystallize in a rhombohedral supercell of the cubic pyrochlore structure, in the space group R-3m. Magnetic susceptibility measurements show no signs of magnetic ordering above 2 K. The RE{sub 3}Sb{sub 3}Mg{sub 2}O{sub 14} family is similar to that of RE{sub 3}Sb{sub 3}Zn{sub 2}O{sub 14}; however, the series reported here features a fully ordered distribution of cations in both the nonmagnetic antimony and magnetic rare earth kagome lattices. Unlike the offsite disorder that Zn{sup 2+} experiences in RE{sub 3}Sb{sub 3}Zn{sub 2}O{sub 14}, the magnesium sites in RE{sub 3}Sb{sub 3}Mg{sub 2}O{sub 14} are completely ordered. Here we compare the magnetic properties in both series of kagome compounds to determine how significant Zn{sup 2+}'s positional ordering is within this structure type. The compounds reported here appear to be relatively defect-free and are therefore model systems for investigating magnetic frustration on an ideal 2D rare earth kagome lattice. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. From Bi-facial Truth to Bi-facial Proofs

    NARCIS (Netherlands)

    Wintein, S.; Muskens, R.A.

    2014-01-01

    In their recent paper Bi-facial truth: a case for generalized truth values Zaitsev and Shramko [7] distinguish between an ontological and an epistemic interpretation of classical truth values. By taking the Cartesian product of the two disjoint sets of values thus obtained, they arrive at four

  18. Fast reversible laser-induced crystallization of Sb-rich Zn-Sb-Se phase change material with excellent stability

    Directory of Open Access Journals (Sweden)

    Yimin Chen

    2015-07-01

    Full Text Available We present a new reversible phase-change medium Sb-rich Zn-Sb-Se film, which possesses a large difference in both optical and electrical constant. The doped-ZnSb, sub-formed Zn-Se, and exhausted Sb-Se3/2 co-influence the physical properties. Typically, there is ∼105 resistance ratio and ∼14% relative reflectivity change in Zn19Sb45.7Se35.3 film when switched by electricity or laser pulses between amorphous and crystalline states. The higher Tc (∼250°C, larger Ea (∼8.57eV, better 10-yr data retention (∼200.2°C, higher crystallization resistance (∼3 × 103Ω/□ at 300°C-annealled and relative lower melting temperature (∼550.2°C are exhibited in Zn19Sb45.7Se35.3 film. Importantly, a short crystalline time (∼80ns at 70mW of the ideal Zn19Sb45.7Se35.3 film can be obtained without sacrificing room-temperature stability.

  19. Centrosymmetry vs noncentrosymmetry in La{sub 2}Ga{sub 0.33}SbS{sub 5} and Ce{sub 4}GaSbS{sub 9} based on the interesting size effects of lanthanides: Syntheses, crystal structures, and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hua-Jun, E-mail: cszzl772002@yeah.net [Laboratory of Applied Research on the Characteristic Resources in the North of Guizhou Province, School of Chemistry and Chemical Engineering, Zunyi Normal College, Zunyi, Guizhou 563002 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2016-05-15

    Two new quaternary sulfides La{sub 2}Ga{sub 0.33}SbS{sub 5} and Ce{sub 4}GaSbS{sub 9} have been prepared from stoichiometric elements at 1223 K in an evacuated silica tube. Interestingly, La{sub 2}Ga{sub 0.33}SbS{sub 5} crystallizes in the centrosymmetric structure, while Ce{sub 4}GaSbS{sub 9} crystallizes in the noncentrosymmetric structure, which show obvious size effects of lanthanides on the crystal structures of these two compounds. Ce{sub 4}GaSbS{sub 9} belongs to RE{sub 4}GaSbS{sub 9} (RE=Pr, Nd, Sm, Gd–Ho) structure type with a=13.8834(9) Å, b=14.3004(11) Å, c=14.4102(13) Å, V=2861.0(4) Å{sup 3}. The structure features infinite chains of [Ga{sub 2}Sb{sub 2}S{sub 11}{sup 10–}]{sub ∞} propagating along a direction separated by Ce{sup 3+} cations and S{sup 2−} anions. La{sub 2}Ga{sub 0.33}SbS{sub 5} adopts the family of La{sub 4}FeSb{sub 2}S{sub 10}-related structure with a=7.5193(6) Å, c=13.4126(17) Å, V=758.35(13) Å{sup 3}. Its structure is built up from the alternate stacking of La/Sb/S and La/Ga/S 2D building blocks. The La/Sb/S slabs consist of teeter-totter chains of Sb1S{sub 4} seesaws, which are connected via sharing the apexes of μ{sub 4}-S1. Moreover, La1 is positionally disordered with Sb1 and stabilized in a bicapped trigonal prismatic coordination sphere. Between these La/Sb/S slabs, La2S{sub 8} square antiprisms are connected via edge-sharing into 2D building blocks, creating tetrahedral sites partially occupied by the Ga1 atoms. UV/Vis diffuse reflectance spectroscopy study shows that the optical gap of La{sub 2}Ga{sub 0.33}SbS{sub 5} is about 1.76 eV. - Graphical abstract: Two new quaternary sulfides La{sub 2}Ga{sub 0.33}SbS{sub 5} and Ce{sub 4}GaSbS{sub 9} have been prepared by solid-state reactions. Ce{sub 4}GaSbS{sub 9} crystallizes in RE{sub 4}GaSbS{sub 9} (RE=Pr, Nd, Sm, Gd–Ho) structure type, while La{sub 2}Ga{sub 0.33}SbS{sub 5} belongs to the family of La{sub 4}FeSb{sub 2}S{sub 10}-related structure and exhibits an

  20. New Insight on Tuning Electrical Transport Properties via Chalcogen Doping in n-type Mg3Sb2-Based Thermoelectric Materials

    DEFF Research Database (Denmark)

    Zhang, Jiawei; Song, Lirong; Borup, Kasper

    2018-01-01

    effective mass resulting from the enhancing chemical bond covalency, which is supported by the decreasing theoretical density of states. According to the above trends, a simple guiding principle based on electronegativity is proposed to shed new light on n-type doping in Zintl antimonides.......n-type Mg3Sb1.5Bi0.5 has recently been discovered to be a promising thermoelectric material, yet the effective n-type dopants are mainly limited to the chalcogens. This may be attributed to the limited chemical insight into the effects from different n-type dopants. By comparing the effects...

  1. Influence of Bi2O3 on sintering and crystallization of cordierite ceramics

    Directory of Open Access Journals (Sweden)

    Đorđević N.

    2005-01-01

    Full Text Available The influence of Bi2O3 on the process of cordierite ceramics preparation, 2MgO-2Al2O3-5SiO2 (MAS was investigated. The following binary systems were used for the presented research: MgO/Bi2O3 (sintered at 820ºC and 1100ºC, Al2O3/Bi2O3 and SiO2/Bi2O3 (sintered at 1100ºC. The composition of these systems consisted of 80% of oxide and 20% Bi2O3. The effects of sintering, composition and morphology were investigated by X-ray diffraction, scanning electron microscopy and EDS analysis. It has been found that Bi2O3, besides a liquid phase, forms intermediary unstable compounds with MgO and Al2O3. MAS ceramics were sintered with 10% Bi2O3 at 1000ºC, 1100ºC and 1200ºC. .

  2. Sb{sub 7}Te{sub 3}/ZnSb multilayer thin films for high thermal stability and long data retention phase-change memory

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shiyu; Wu, Weihua [Functional Materials Research Laboratory, School of Materials Science & Engineering, Tongji University, Shanghai 201804 (China); Zhai, Jiwei, E-mail: apzhai@tongji.edu.cn [Functional Materials Research Laboratory, School of Materials Science & Engineering, Tongji University, Shanghai 201804 (China); Song, Sannian; Song, Zhitang [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Science, Shanghai 200050 (China)

    2017-04-15

    Highlights: • Sb{sub 7}Te{sub 3} (ST) provides a fast crystallization speed, low melting temperature. • The Sb{sub 7}Te{sub 3}/ZnSb films exhibits faster crystallization speed, high thermal stability. • The calculated temperature for 10-year data retention is about 127 {sup o}C. • The Sb{sub 7}Te{sub 3}/ZnSb multilayer configuration with low power consumption. - Abstract: Phase-change memory is regard as one of the most promising candidates for the next-generation non-volatile memory. In this work, we proposed a Sb{sub 7}Te{sub 3}/ZnSb multilayer thin films to improve the thermal stability of Sb-rich Sb{sub 3}Te{sub 7}. The sheet resistance ratio between amorphous and crystalline states reached up to 4 orders of magnitude. With regard to the thermal stability, the calculated temperature for 10-year data retention is about 127 °C. The threshold current and threshold voltage of a cell based on Sb{sub 7}Te{sub 3}/ZnSb are 6.9 μA and 1.9 V, respectively. The lower RESET power is presented in the PCM cells of Sb{sub 7}Te{sub 3}/ZnSb films, benefiting from its high resistivity.

  3. Design, fabrication, and characterization of InSb avalanche photodiode

    Science.gov (United States)

    Abautret, J.; Evirgen, A.; Perez, J. P.; Christol, P.; Rouvié, A.; Cluzel, R.; Cordat, A.; Rothman, J.

    2013-12-01

    In this communication, the potentiality of InSb material as an avalanche photodiode (APD) device is investigated. Current density-voltage (J-V) characteristics at 77K of InSb pin photodiodes were simulated by using ATLAS software from SILVACO, in dark conditions and under illumination. In order to validate parameter values used for the modeling, theoretical J-V results were compared with experimental measurements performed on InSb diodes fabricated by molecular beam epitaxy. Next, assuming a multiplication process only induced by the electrons (e-APD), different designs of separate absorption and multiplication (SAM) APD structure were theoretically investigated and the first InSb SAM APD structure with 1μm thick multiplication layer was then fabricated and characterized.

  4. Modeling the AgInSbTe Memristor

    Directory of Open Access Journals (Sweden)

    J. Yu

    2015-09-01

    Full Text Available The AgInSbTe memristor shows gradual resistance tuning characteristics, which makes it a potential candidate to emulate biological plastic synapses. The working mechanism of the device is complex, and both intrinsic charge-trapping mechanism and extrinsic electrochemical metallization effect are confirmed in the AgInSbTe memristor. Mathematical model of the AgInSbTe memristor has not been given before. We propose the flux-voltage controlled memristor model. With piecewise linear approximation technique, we deliver the flux-voltage controlled memristor model of the AgInSbTe memristor based on the experiment data. Our model fits the data well. The flux-voltage controlled memristor model and the piecewise linear approximation method are also suitable for modeling other kinds of memristor devices based on experiment data.

  5. Hall Mobility of Amorphous Ge2Sb2Te5

    National Research Council Canada - National Science Library

    Baily, S. A; Emin, David; Li, Heng

    2006-01-01

    The electrical conductivity, Seebeck coefficient, and Hall coefficient of 3 micron thick films of amorphous Ge2Sb2Te5 have been measured as functions of temperature from room temperature down to as low as 200 K...

  6. Low-energy surface states in the normal state of α -PdBi2 superconductor

    Science.gov (United States)

    Choi, Hongchul; Neupane, Madhab; Sasagawa, T.; Chia, Elbert E. M.; Zhu, Jian-Xin

    2017-08-01

    Topological superconductors as characterized by Majorana surface states have been actively searched for their significance in fundamental science and technological implication. The large spin-orbit coupling in Bi-Pd binaries has stimulated extensive investigations on the topological surface states in these superconducting compounds. Here we report a study of normal-state electronic structure in a centrosymmetric α -PdBi2 within density functional theory calculations. By investigating the electronic structure from the bulk to slab geometries in this system, we predict that α -PdBi2 can host orbital-dependent and asymmetric Rashba surface states near the Fermi energy. This study suggests that α -PdBi2 will be a good candidate to explore the relationship between superconductivity and topology in condensed matter physics.

  7. Supplementary X-ray studies of the Ni-Sn-Bi system

    Directory of Open Access Journals (Sweden)

    Vassilev G.P.

    2007-01-01

    Full Text Available Phase equilibria were studied in the system Ni-Sn-Bi. Special attention has been paid to the identification of the recently found ternary phase. For this purpose samples were synthesized using intimately mixed powders. After annealing and quenching, all alloys were analyzed by scanning electron microscope and by X-ray diffraction. The results give evidences about the existence of a ternary compound with approximate formula Ni6Sn2Bi to Ni7Sn2Bi. Overlapping of some neighboring diffraction peaks of this phase with NiBi and Ni3Sn_LT is the reason for the difficulties related to the X-ray diffraction identification of the ternary phase.

  8. Valence Band Structure of InAs1-xBix and InSb1-xBix Alloy Semiconductors Calculated Using Valence Band Anticrossing Model

    Directory of Open Access Journals (Sweden)

    D. P. Samajdar

    2014-01-01

    Full Text Available The valence band anticrossing model has been used to calculate the heavy/light hole and spin-orbit split-off energies in InAs1-xBix and InSb1-xBix alloy systems. It is found that both the heavy/light hole, and spin-orbit split E+ levels move upwards in energy with an increase in Bi content in the alloy, whereas the split E− energy for the holes shows a reverse trend. The model is also used to calculate the reduction of band gap energy with an increase in Bi mole fraction. The calculated values of band gap variation agree well with the available experimental data.

  9. Interplay of Dirac electrons and magnetism in CaMnBi2 and SrMnBi2.

    Science.gov (United States)

    Zhang, Anmin; Liu, Changle; Yi, Changjiang; Zhao, Guihua; Xia, Tian-Long; Ji, Jianting; Shi, Youguo; Yu, Rong; Wang, Xiaoqun; Chen, Changfeng; Zhang, Qingming

    2016-12-16

    Dirac materials exhibit intriguing low-energy carrier dynamics that offer a fertile ground for novel physics discovery. Of particular interest is the interplay of Dirac carriers with other quantum phenomena such as magnetism. Here we report on a two-magnon Raman scattering study of AMnBi2 (A=Ca, Sr), a prototypical magnetic Dirac system comprising alternating Dirac carrier and magnetic layers. We present the first accurate determination of the exchange energies in these compounds and, by comparison with the reference compound BaMn2Bi2, we show that the Dirac carrier layers in AMnBi2 significantly enhance the exchange coupling between the magnetic layers, which in turn drives a charge-gap opening along the Dirac locus. Our findings break new grounds in unveiling the fundamental physics of magnetic Dirac materials, which offer a novel platform for probing a distinct type of spin-Fermion interaction. The results also hold great promise for applications in magnetic Dirac devices.

  10. Monte Carlo calculation of electron transport in InSb

    CERN Document Server

    Mallick, P S

    2002-01-01

    The velocity field characteristics of InSb have been obtained at 77 K by the Monte Carlo simulation technique. The results agree with the experimental data and also with those obtained by using the displaced Maxwellian distribution function. The effects of the various simulation parameters as well as that of the ionized impurity concentration on the mobility values for InSb have been discussed and results presented. (author)

  11. Wafer-scale processing technology for monolithically integrated GaSb thermophotovoltaic device array on semi-insulating GaAs substrate

    Science.gov (United States)

    Kim, Jung Min; Dutta, Partha S.; Brown, Eric; Borrego, Jose M.; Greiff, Paul

    2013-06-01

    This paper presents the entire fabrication and processing steps necessary for wafer scale monolithic integration of series interconnected GaSb devices grown on semi-insulating GaAs substrates. A device array has been fabricated on complete 50 mm (2 inch) diameter wafer using standard photolithography, wet chemical selective etching, dielectric deposition and single-sided metallization. For proof of concept of the wafer-scale feasibility of this process, six large-area series interconnected GaSb p-n junction thermophotovoltaic cells with each cell consisting of 24 small-area devices have been fabricated and characterized for its electrical connectivity. The fabrication process presented in this paper can be used for optoelectronic and electronic device technologies based on GaSb and related antimonide based compound semiconductors.

  12. Structural and optoelectronic properties of BxAl1-xSb ternary alloys: first principles calculations

    Science.gov (United States)

    Benchehima, Miloud; Abid, Hamza; Chaouche, Abdallah Chabane; Resfa, Abbes

    2017-03-01

    In this paper, the full potential linearized augmented plane wave (FP-LAPW) formalism based on density functional theory (DFT) has been performed. To study the structural properties of BxAl1-xSb at different boron concentrations x (0 ≤ x ≤ 1), we have used the local density approximation (LDA) and the generalized gradient approximation of Wu and Cohen (GGA-WC). The phase stability of AlSb and BSb binary compounds in zinc-blend and rock salt phases has been investigated. The equilibrium lattice constant (a), bulk modulus (B) and pressure derivative of bulk modulus B' have been evaluated in both phases. We observe a small deviation from the linear concentration dependence (LCD) of the lattice constant parameter, while an important deviation of bulk modulus from "LCD" has been remarked. We have compared the results obtained to the available theoretical and experimental data for the binaries. The optoelectronic properties of BxAl1-xSb are studied in the most stable determined phase. In addition to the "GGA-WC", the GGA of Engel and Vosko, and the recent developed Tran-Blaha-modified Becke-Johnson (TB-mBJ) schemes were used to study the electronic properties of BxAl1-xSb ternary alloys. It is found that the band gap of BxAl1-xSb vary non-linearly with the boron concentrations, giving a negative deviation from Vegard's law. In addition, the optical properties such as the dielectric function, complex refractive index, absorption coefficient, optical conductivity and absorption coefficient are discussed in detail.

  13. First-principles study of new series of quaternary Heusler alloys CsSrCZ (Z=Si, Ge, Sn, P, As, and Sb)

    Energy Technology Data Exchange (ETDEWEB)

    Bouabça, A. [Condensed Matter and Sustainable Development Laboratory (LMCDD), University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria); Rozale, H., E-mail: hrozale@yahoo.fr [Condensed Matter and Sustainable Development Laboratory (LMCDD), University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria); Amar, A. [Condensed Matter and Sustainable Development Laboratory (LMCDD), University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria); Wang, X.T. [School of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400044 (China); Sayade, A. [UCCS, CNRS-UMR 8181, Université d’Artois, Faculté des Sciences Jean Perrin, Rue Jean Souvraz, SP 18, 62307 Lens Cedex (France); Chahed, A. [Condensed Matter and Sustainable Development Laboratory (LMCDD), University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria)

    2016-12-01

    The structural, electronic, magnetic, and thermal properties of new quaternary Heusler alloys CsSrCZ (Z=Si, Ge, Sn, P, As, and Sb) were investigated using the full-potential linearized augmented plane wave (FPLAPW) within the generalized gradient approximation (GGA) and GGA plus modified Becke and Johnson as the exchange correlation. The results showed that all Heusler compounds were stable in Type (I) structure. The CsSrCZ (Z=Si, Ge, Sn) compounds had a nearly HM characteristic, and CsSrCZ (Z=P, As, Sb) compounds were true half-metallic (HM) ferromagnets. The strong spin polarization of p orbital for C, Si, Ge, Sn, P, As, and Sb atoms is found to be the origin of ferromagnetic. The half-metallicity is preserved up to a lattice contraction of 3.45%, 1.69%, 1.69%, 7.16%, 7.16%, and 11.2% for all six quaternary Heusler compounds. We also investigated the thermal effects using the quasi-harmonic Debye model. - Highlights: • Electronic, magnetic, and thermodynamic properties of CsSrCZ (Z=Si, Ge, Sn, P, As, and Sb) are investigated. • Until now, there have been no reports theoretical and experimental studies on d{sup 0} half-metals with quaternary structures. • The strong spin polarization of p orbital for C, Si, Ge, Sn, P, As, and Sb atoms is found to be the origin of ferromagnetic. • The half-metallicity is preserved up to a lattice contraction.

  14. Synthesis and characterization of O3-Na{sub 3}LiFeSbO{sub 6}: A new honeycomb ordered layered oxide

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Whitney; Berthelot, Romain [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States); Etienne, Laetitia; Wattiaux, Alain [CNRS, Université de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, 33608 F-Pessac (France); Subramanian, M.A., E-mail: mas.subramanian@oregonstate.edu [Department of Chemistry, Oregon State University, Corvallis, OR 97331 (United States)

    2014-02-01

    Highlights: • A new honeycomb ordered layered oxide Na{sub 3}LiFeSbO{sub 6} was synthesized. • This compound crystallizes in the C2/c space group. • Disorder in the honeycomb arrangement of Li and Fe is present. - Abstract: A new compound Na{sub 3}LiFeSbO{sub 6} has been synthesized by conventional solid state methods and investigated using X-ray diffraction, DC magnetic susceptibility, {sup 57}Fe Mössbauer spectroscopy and optical measurements. This compound crystallizes in a monoclinic unit cell and is related to a family of honeycomb ordered layered oxide materials where Na{sup +} fills octahedral interlayer sites between Li{sub 1/3}Fe{sub 1/3}Sb{sub 1/3}O{sub 2} slabs of edge sharing octahedra. Each SbO{sub 6} octahedron is surrounded by LiO{sub 6} and FeO{sub 6} octahedra creating a honeycomb arrangement within the slabs. Powder X-ray diffraction indicates the presence of stacking faults. This compound exhibits Curie–Weiss behavior at high temperatures and the effective magnetic moment verifies the presence of high spin Fe{sup 3+}. The {sup 57}Fe Mössbauer spectroscopy confirms Fe{sup 3+} in an octahedral position and indicates disorder in the arrangement of LiO{sub 6} and FeO{sub 6} octahedra in the Li{sub 1/3}Fe{sub 1/3}Sb{sub 1/3}O{sub 2} slabs.

  15. Improvement of reliability and speed of phase change memory devices with N7.9(Ge46.9Bi7.2Te45.9 films

    Directory of Open Access Journals (Sweden)

    J. H. Park

    2015-08-01

    Full Text Available In this study, we propose a nitrogen-incorporated GeBiTe ternary phase of N7.9(Ge46.9Bi7.2Te45.9 as a phase change material for reliable PCM (Phase Change Memory with high speed operation. We found that the N7.9(Ge46.9Bi7.2Te45.9 film shows the resistance value of 40 kΩ after annealing at 440oC for 10 minutes, which is much higher than the value of 3.4 kΩ in the case of conventional N7.0(Ge22.0Sb22.0Te56.0 films. A set operation time of 14 nsec was achieved in the devices due to the increased probability of the nucleation by the addition of the elemental Bi. The long data retention time of 10 years at 85oC on the base of 1% failure was obtained as the result of higher activation energy of 2.52 eV for the crystallization compared to the case of N7.0(Ge22.0Sb22.0Te56.0 film, in which the activation energy is 2.1 eV. In addition, a reset current reduction of 27% and longer cycles of endurance as much as 2 order of magnitude compared to the case of N7.0(Ge22.0Sb22.0Te56.0 were observed at a set operation time of 14 nsec. Our results show that N7.9(Ge46.9Bi7.2Te45.9 is highly promising for use as a phase change material in reliable PCMs with high performance and also in forthcoming storage class memory applications, too.

  16. Electronic structure and photocatalytic activities of (Bi2-δYδ)Sn2O7 solid solution

    Science.gov (United States)

    Fan, Wenjie; Hu, Jinli; Huang, Jing; Wu, Xin; Lin, Sen; Huang, Caijin; Qiu, Xiaoqing

    2015-12-01

    A series of (Bi2-δYδ)Sn2O7 solid solutions were prepared by a one-step hydrothermal method to investigate the correlation between the electronic structures and photocatalytic activity. All the (Bi2-δYδ)Sn2O7 samples were characterized by X-ray diffraction, transmission electron microscopy, infrared and UV-vis absorption spectroscopy, and the Brunauer-Emmett-Teller technique. The effects of Bi 6s orbitals in (Bi2-δYδ)Sn2O7 solid solutions on the electronic structures and photogradation of colorless 2-naphthol solution were investigated experimentally and theoretically. It is found that the introduction of Y3+ induces the shrinkage of the lattice of (Bi2-δYδ)Sn2O7 solid solutions. Consequently, the contribution of Bi 6s orbitals to electronic structures of (Bi2-δYδ)Sn2O7 solid solutions can be continuously tuned by Y3+ substitution for Bi3+. Density function theory calculations reveal that the Bi 6s and O 2p states dominate the top of valence band of Bi2Sn2O7, while the bottom of conduction band mainly consists of the states of Sn 5s, O 2p and Bi 6p. Once the Bi3+ ions are substituted by Y3+, the intensity of Bi 6s states is weakening at the top of valence band while the bottom of conduction band retains the same feature observed for pure Bi2Sn2O7. Moreover, the band dispersions of valence band and conduction band become narrower after Y3+ introduction into the lattice of (Bi2-δYδ)Sn2O7 solid solutions. As a result, the photocatalytic performance for decomposition of 2-naphthol has been suppressed by the Y3+ substitution, since the electronic structure limits the mobility of the photoinduced charge carriers. Our results suggest that high photocatalytic activity of Bi-containing compounds should originate from the good band dispersions of valence band and conduction band involving the Bi 6s orbitals.

  17. Etanercept (SB4): A Review in Autoimmune Inflammatory Diseases.

    Science.gov (United States)

    Burness, Celeste B; Duggan, Sean T

    2016-08-01

    Etanercept (SB4) [Benepali(®)], a tumour necrosis factor inhibitor that is a biosimilar of reference etanercept (Enbrel(®)), is approved in the EU for use in all adult indications for which reference etanercept is approved, namely rheumatoid arthritis, axial spondyloarthritis (ankylosing spondylitis and non-radiographic axial spondyloarthritis), psoriatic arthritis, and plaque psoriasis. The approval of etanercept (SB4) was based on the results of stringent comparability exercises designed to demonstrate similarity to reference etanercept in terms of quality, biological activity, efficacy, safety, and immunogenicity. In two well-designed clinical trials, etanercept (SB4) was equivalent to reference etanercept with regard to pharmacokinetic properties in healthy volunteers and in terms of efficacy in patients with moderate to severe rheumatoid arthritis despite methotrexate therapy. Longer-term efficacy (up to 52 weeks) was also similar in both treatment groups. Etanercept (SB4) was generally well tolerated, with a similar safety profile to that of reference etanercept. Preliminary results of the open-label extension period (100 weeks) suggest that transitioning from reference etanercept to etanercept (SB4) was associated with sustained efficacy and no change in the adverse event profile or immunogenicity. In conclusion, etanercept (SB4) provides therapeutically equivalent alternative in adult patients with autoimmune inflammatory diseases requiring treatment with etanercept.

  18. High Current Density InAsSb/GaSb Tunnel Field Effect Transistors

    OpenAIRE

    Dey, Anil; Borg, Mattias; Ganjipour, Bahram; Ek, Martin; Dick Thelander, Kimberly; Lind, Erik; Nilsson, Peter; Thelander, Claes; Wernersson, Lars-Erik

    2012-01-01

    Steep-slope devices, such as tunnel field-effect transistors (TFETs), have recently gained interest due to their potential for low power operation at room temperature. The devices are based on inter-band tunneling which could limit the on-current since the charge carriers must tunnel through a barrier to traverse the device. The InAs/GaSb heterostructure forms a broken type II band alignment which enables inter-band tunneling without a barrier, allowing high on-currents. We ha...

  19. Ferro electrical properties of GeSbTe thin films; Propiedades ferroelectricas de peliculas delgadas de GeSbTe

    Energy Technology Data Exchange (ETDEWEB)

    Gervacio A, J. J.; Prokhorov, E.; Espinoza B, F. J., E-mail: jgervacio@qro.cinvestav.m [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico)

    2011-07-01

    The aim of this work is to investigate and compare ferro electrical properties of thin GeSbTe films with composition Ge{sub 4}Sb{sub 1}Te{sub 5} (with well defined ferro electrical properties) and Ge{sub 2}Sb{sub 2}Te{sub 5} using impedance, optical reflection, XRD, DSc and Piezo response Force Microscopy techniques. The temperature dependence of the capacitance in both materials shows an abrupt change at the temperature corresponding to ferroelectric-paraelectric transition and the Curie-Weiss dependence. In Ge{sub 2}Sb{sub 2}Te{sub 5} films this transition corresponds to the end from a NaCl-type to a hexagonal transformation. Piezo response Force Microscopy measurements found ferroelectric domains with dimension approximately equal to the dimension of grains. (Author)

  20. Magnetic properties of GdPdSb and GdNiSb studied by {sup 155}Gd-Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bielemeier, B. [Department Physik, Universitaet Paderborn, D-33098 Paderborn (Germany); Wortmann, G. [Department Physik, Universitaet Paderborn, D-33098 Paderborn (Germany)], E-mail: Wortmann@physik.upb.de; Casper, F.; Ksenofontov, V.; Felser, C. [Institut fuer Anorg. und Analyt. Chemie, Johannes Gutenberg-Universitaet, D-55099 Mainz (Germany)

    2009-07-01

    {sup 155}Gd-Moessbauer spectroscopy was applied to study the magnetic properties of GdPdSb with hexagonal LiGaGe structure and of GdNiSb in the cubic MgAgAs-type structure as well as in the hexagonal AlB{sub 2}-type structure. In GdPdSb magnetic ordering is observed at 13.0 K with indications of a tilted spin structure at lower temperatures. In the cubic phase of GdNiSb magnetic ordering is observed at 9.5 K and in the hexagonal phase around 3.5 K. These results are discussed in conjunction with previous investigations of these samples.

  1. Crystal structure, magnetism, {sup 89}Y solid state NMR, and {sup 121}Sb Moessbauer spectroscopic investigations of YIrSb

    Energy Technology Data Exchange (ETDEWEB)

    Benndorf, Christopher [Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Heletta, Lukas; Block, Theresa; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Eckert, Hellmut [Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Institute of Physics in Sao Carlos, University of Sao Paulo, Sao Carlos (Brazil)

    2017-02-15

    The ternary antimonide YIrSb was synthesized from the binary precursor YIr and elemental antimony by a diffusion controlled solid-state reaction. Single crystals were obtained by a flux technique with elemental bismuth as an inert solvent. The YIrSb structure (TiNiSi type, space group Pnma) was refined from single-crystal X-ray diffractometer data: a = 711.06(9), b = 447.74(5), c = 784.20(8) pm, wR{sub 2} = 0.0455, 535 F{sup 2} values, 20 variables. {sup 89}Y solid state MAS NMR and {sup 121}Sb Moessbauer spectra show single resonance lines in agreement with single-crystal X-ray data. YIrSb is a Pauli paramagnet. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Design of medium band gap Ag-Bi-Nb-O and Ag-Bi-Ta-O semiconductors for driving direct water splitting with visible light.

    Science.gov (United States)

    Wang, Limin; Cao, Bingfei; Kang, Wei; Hybertsen, Mark; Maeda, Kazuhiko; Domen, Kazunari; Khalifah, Peter G

    2013-08-19

    Two new metal oxide semiconductors belonging to the Ag-Bi-M-O (M = Nb, Ta) chemical systems have been synthesized as candidate compounds for driving overall water splitting with visible light on the basis of cosubstitution of Ag and Bi on the A-site position of known Ca2M2O7 pyrochlores. The low-valence band edge energies of typical oxide semiconductors prevents direct water splitting in compounds with band gaps below 3.0 eV, a limitation which these compounds are designed to overcome through the incorporation of low-lying Ag 4d(10) and Bi 6s(2) states into compounds of nominal composition "AgBiM2O7". It was found that the "AgBiTa2O7" pyrochlores are in fact a solid solution with an approximate range of Ag(x)Bi(5/6)Ta2O(6.25+x/2) with 0.5 semiconductors with the onset of strong direct absorption at 2.72 and 2.96 eV, respectively. Electronic structure calculations for an ordered AgBiNb2O7 structure show that the band gap reduction and the elevation of the valence band primarily result from hybridized Ag d(10)-O 2p orbitals that lie at higher energy than the normal O 2p states in typical pyrochlore oxides. While the minimum energy gap is direct in the band structure, the lowest energy dipole allowed optical transitions start about 0.2 eV higher in energy than the minimum energy transition and involve different bands. This suggests that the minimum electronic band gap in these materials is slightly smaller than the onset energy for strong absorption in the optical measurements. The elevated valence band energies of the niobate and tantalate compounds are experimentally confirmed by the ability of these compounds to reduce 2 H(+) to H2 gas when illuminated after functionalization with a Pt cocatalyst.

  3. An unusual ligand in copper chemistry: coordination oligomers and polymers containing the [[CpMo(CO)2]2(mu,eta2-Sb2)] cluster.

    Science.gov (United States)

    Ly, Hanh V; Parvez, Masood; Roesler, Roland

    2006-01-09

    The coordination behavior of [[CpMo(CO)(2)}(2)(mu,eta(2)-Sb(2))] (1; Cp = cyclopentadiene) toward Cu(I) was investigated. Its reaction with CuX (X = Br, Cl, and I) produced oligomers or polymers of the general formula [[CpMo(CO)(2)](2)(mu,eta(2)-Sb(2))(mu-CuX)](n). While 2 (X = Cl, n = 2) and 3 (X = Br, n = 2) proved to be halogen-bridged dimers in both solution and solid state, the molecules of 4 (X = I, n = infinity) self-assembled in the crystal forming a linear polymer with a Cu-I skeleton supported by Sb-Cu bonds. The reaction of 1 with Cu[GaCl(4)] resulted in the formation of the ionic complex [[CpMo(CO)(2)](2)(mu,eta(2)-Sb(2))](4)Cu(2)[GaCl(4)](2) (5). Its dication contains four [[CpMo(CO)(2)](2)(mu,eta(2)-Sb(2))] ligands arranged around a Cu-Cu dumbbell. All new compounds were characterized using IR, electrospray ionization mass spectrometry, (1)H NMR, elemental analysis, and single-crystal X-ray diffraction. The ligand was oxidized by both silver(I) and copper(II), and a cyclovoltammetric study revealed that 1 suffered irreversible reduction and oxidation in a dichloromethane solution at -2.04 and 0.10 V, respectively, versus ferrocene.

  4. AgSbSe{sub 2} and AgSb(S,Se){sub 2} thin films for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Garza, J.G. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Shaji, S. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Facultad de Ingenieria Mecanica y Electrica, CIIDIT - Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Rodriguez, A.C.; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Krishnan, B., E-mail: kbindu_k@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Facultad de Ingenieria Mecanica y Electrica, CIIDIT - Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2011-10-01

    Silver antimony selenide (AgSbSe{sub 2}) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb{sub 2}S{sub 3}), silver selenide (Ag{sub 2}Se), selenium (Se) and silver (Ag). Sb{sub 2}S{sub 3} thin film was prepared from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3}, Ag{sub 2}Se from a solution containing AgNO{sub 3} and Na{sub 2}SeSO{sub 3} and Se thin films from an acidified solution of Na{sub 2}SeSO{sub 3}, at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 deg. C in vacuum (10{sup -3} Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe{sub 2} or AgSb(S,Se){sub 2} depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe{sub 2}/Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed V{sub oc} = 435 mV and J{sub sc} = 0.08 mA/cm{sup 2} under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe{sub 2} as an absorber material by a non-toxic selenization process is achieved.

  5. Phase transitions in double perovskite Sr2ScSbO6: An Ab-initio study

    Science.gov (United States)

    Ray, Rajyavardhan; Himanshu, Ajay K.; Brajesh, Kumar; Bandyopadhyay, S. K.; Kumar, Uday; Sinha, T. P.

    2014-04-01

    First Principles study of the electronic properties of recently synthesized double perovskite Sr2ScSbO6 have been performed using density functional theory. With increasing temperature, the Sr compound undergoes three structural phase transitions at 400K, 550K and 650K approximately, leading to the following sequence of phases: P21/n → I2/m → I4/m → Fm-3m. Starting from the monoclinic phase P21/n at room temperature, resulting from the Sc/Sb ordering, the electronic structure for the tetragonal I4/m at 613K and cubic Fm-3m for T≥660K has been studied in terms of the density of states and band-structure. Presence of large band gap, both direct and indirect, has been reported and analyzed.

  6. Phase transitions in double perovskite Sr{sub 2}ScSbO{sub 6}: An Ab-initio study

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Rajyavardhan, E-mail: rajyavardhanray@gmail.com [Department of Physics, Indian Institute of Technology Kanpur, Kanpur-208016, India and Nanostructured and Advanced Material Laboratory, Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Saltlake, Kolkata-700064 (India); Himanshu, Ajay K.; Bandyopadhyay, S. K. [Nanostructured and Advanced Material Laboratory, Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Saltlake, Kolkata-700064 (India); Brajesh, Kumar [Department of Physics, Veer Kunwar Singh University, Ara-802301, Bihar (India); Kumar, Uday [Department of Physical Sciences, IISER, Mohanpur Campus, Mohanpur-741252, West Bengal (India); Sinha, T. P. [Department of Physics, Bose Institute, Kolkata-700042 (India)

    2014-04-24

    First Principles study of the electronic properties of recently synthesized double perovskite Sr{sub 2}ScSbO{sub 6} have been performed using density functional theory. With increasing temperature, the Sr compound undergoes three structural phase transitions at 400K, 550K and 650K approximately, leading to the following sequence of phases: P21/n → I2/m → I4/m → Fm-3m. Starting from the monoclinic phase P21/n at room temperature, resulting from the Sc/Sb ordering, the electronic structure for the tetragonal I4/m at 613K and cubic Fm-3m for T≥660K has been studied in terms of the density of states and band-structure. Presence of large band gap, both direct and indirect, has been reported and analyzed.

  7. On the possibility of thermoelectricity in half Heusler XRuSb (X = V, Nb, Ta) materials: A first principles prospective

    Science.gov (United States)

    Kaur, Kulwinder; Kumar, Ranjan

    2017-11-01

    In this study, we explored the electronic and thermoelectric properties of three semiconducting half Heusler compounds XRuSb (X = V, Nb, Ta) using density functional theory and semi-classical Boltzmann transport theory. We calculated the Seebeck coefficient and the electrical, electronic, and lattice thermal conductivity with changes in the temperature. These materials were identified as good thermoelectric materials with narrow band gaps and flat electronic bands in the valence band. The Seebeck coefficient and electronic thermal conductivity increased with temperature. The electrical conductivity and lattice thermal conductivity decreased as the temperature increased. The calculations indicated that p-type doping had a higher power factor than n-type doping. The spin orbit coupling (SOC) effect on the thermoelectric properties was also considered. The relaxation time (τ) decreased as the temperature increased. The maximum value for the figure of merit was equal to 0.13, which was achieved by VRuSb.

  8. Observation of Sb sub 2 O sub 3 nanocrystals in SiO sub 2 after Sb ion implantation

    CERN Document Server

    Ignatova, V A; Gijbels, R; Adams, F; Lebedev, O I; Landuyt, J V; Waetjen, U

    2002-01-01

    Antimony nanocrystals were formed in thin SiO sub 2 films using low-energy ion implantation of Sb followed by annealing. Using Fourier transform laser microprobe mass spectrometry (FT LMMS), we observed for the first time the presence of antimony oxide in the intermediate phase (as-implanted layer of Sb) by means of signals referring to the intact Sb sub 2 O sub 3 molecules. Only SbO sup + fragments, but no adduct ions of Sb sub 2 O sub 3 could be detected in annealed samples. The size and the distribution of the nanocrystals formed around the initial depth of implantation were studied in the as-implanted samples by high-resolution electron microscopy (HREM). The crystalline structure of these nanocrystals was also studied and the presence of antimony trioxide Sb sub 2 O sub 3 in the form of valentinite was proven. After the annealing step, the implanted material had spread into a wider band. The method introduced here, based on combining TEM (transmission electron microscopy) and FT LMMS results, offers the ...

  9. Gel-combustion synthesis of CoSb2O6 and its reduction to powdery Sb2Co alloy

    Directory of Open Access Journals (Sweden)

    MAJA JOVIC

    2009-01-01

    Full Text Available Sb2Co alloy in powdery form was synthesized via reduction with gaseous hydrogen of the oxide CoSb2O6, obtained by the citrate gel-combustion technique. The precursor was an aqueous solution of antimony nitrate, cobalt nitrate and citric acid. The precursor solution with mole ratio Co(II/Sb(V of 1:2 was gelatinized by evaporation of water. The gel was heated in air up to the temperature of self-ignition. The product of gel combustion was a mixture of oxides and it had to be additionally thermally treated in order to be converted to pure CoSb2O6. The reduction of CoSb2O6 by gaseous hydrogen yielded powdery Sb2Co as the sole phase. The process of oxide reduction to alloy was controlled by thermogravimetry, while X-ray diffractometry was used to control the phase compositions of both the oxides and alloys.