Temperature-dependent structural studies of polycrystalline Bi1-xSbx alloys were carried out using synchrotron x-ray diffraction. In-depth powder diffraction analysis reveals that an iso-structural phase transition takes place in the rhombohedral Bi-Sb alloy around 200 K, which is accompanied by anomalous behavior in the temperature-dependent linear thermal expansion data. In addition, the thermal variation of refined isotropic thermal parameters or Debye-Waller factor (B iso), ratio of the lattice parameters and Debye temperature indicates that anisotropy, arising due to local structural disorder, plays a significant role in this material. © 2016, EPLA.

ARITRA BANERJEE

Physics

SUDIPTA BANDYOPADHYAY

K MALIK

D DAS

A K DEB

V SRIHARI

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Evidence of iso-structural phase transition in rhombohedral Bi-Sb alloy

The phonon anharmonicity in Se-doped Sb2Te3 system is probed both macroscopically and microscopically using temperature-dependent synchrotron powder diffraction, Raman spectroscopic studies, and heat-capacity measurements. Gruneisen parameter (γG) is calculated to explain anharmonicity in the polycrystalline Sb2Te3-xSex samples. The thermal variation of structural parameters, structural anisotropy, Debye temperature, velocity of sound, and isothermal compressibility of Sb2Te3-xSex at room temperature are estimated. Analysis revealed that structural anisotropy and phonon anharmonicity are correlated. Further, lattice thermal conductivities (κL), evaluated in the Umklapp scattering limit in terms of γG, indicate that the phonon anharmonicity increasing with Se(x) content reduces κL. A plausible explanation is provided on the basis of Se-doped softening of transverse optical phonon mode. © 2017 American Physical Society.

Physical Review B

Evolution of phonon anharmonicity in Se-doped S b2 T e3 thermoelectrics

Structural, thermal, resistive and magnetic properties of melt quenched Bi0.88Sb0.12 alloys are reported. The samples are heated at three different temperatures, followed by rapid quenching in liquid nitrogen. Large temperature difference between liquidus and solidus lines, led to microscopic in-homogeneity in the alloy. The effect of quenching from different temperatures in polycrystalline Bi0.88Sb0.12 alloy has been studied. The parameters such as strain, unit cell volume, and resistivity are found to increase with temperature. Thermal variation of resistivity depicts non-monotonic temperature dependence. The total negative susceptibility increases and band gap of semiconducting Bi0.88Sb0.12 samples decreases with increasing temperature. © 2015 Elsevier Ltd. All rights reserved.

Fulltext

Journal of Physics and Chemistry of Solids

The effect of quenching from different temperatures on Bi0.88Sb0.12 alloy

We report magneto-resistive properties of direct and indirect band gap Bismuth-Antimony (Bi-Sb) alloys. Band gap increases with magnetic field. Large positive magnetoresistance (MR) approaching to 400% is observed. Low field MR experiences quadratic growth and at high field it follows a nearly linear behavior without sign of saturation. Carrier mobility extracted from low field MR data depicts remarkable high value of around 5 m2V -1s-1. Correlation between MR and mobility is revealed. We demonstrate that the strong nearly linear MR at high field can be well understood by classical method, co-build by Parish and Littlewood, Nature 426, 162 (2003) and Phys. Rev. B 72, 094417 (2005). © 2014 AIP Publishing LLC.

Applied Physics Letters

Magneto-resistive property study of direct and indirect band gap thermoelectric Bi-Sb alloys

Thermal variation of structural property, linear thermal expansion coefficient (α), resistivity (ρ), thermopower (S), and power factor (PF) of polycrystalline Bi1-xSbx (x = 0.10 and 0.14) samples are reported. Temperature-dependent powder diffraction experiments indicate that samples do not undergo any structural phase transition. Rietveld refinement technique has been used to perform detailed structural analysis. Temperature dependence of α is found to be stronger for Bi 0.90Sb0.10. Also, PF for direct band gap Bi 0.90Sb0.10 is higher as compared to that for indirect band gap Bi0.86Sb0.14. Role of electron-electron and electron-phonon scattering on ρ, S, and PF has been discussed. © 2013 AIP Publishing LLC.

Temperature-dependent structural property and power factor of n type thermoelectric Bi0.90Sb0.10 and Bi0.86Sb 0.14 alloys

Polycrystalline Bi 1-xSb x alloys have been synthesized over a wide range of antimony concentration (0.08 ≤ x ≤ 0.20) by solid state reaction method. In depth structural analysis using x-ray diffraction (XRD) and temperature dependent resistivity (ρ) measurement of synthesized samples have been performed. XRD data confirmed single phase nature of polycrystalline samples and revealed that complete solid solution is formed between bismuth and antimony. Rietveld refinement technique, utilizing maud software, has been used to perform detailed structural analysis of the samples and lattice parameters of polycrystalline Bi 1-xSb x alloys have been estimated. Lattice parameter and unit cell volume decreases monotonically with increasing antimony content. The variation of lattice parameters with antimony concentration depicts a distinct slope change at x 0.12. Band gap (E g) has been estimated from the thermal variation of resistivity data, with the 12 Sb content sample showing maximum E g. It has been observed that with increasing antimony concentration the transition from direct to indirect gap semiconductor is intimately related to the variation of the estimated lattice parameters. Band diagram for the polycrystalline Bi 1-xSb x alloy system has also been proposed. © 2012 American Institute of Physics.

Journal of Applied Physics

Sb concentration dependent structural and resistive properties of polycrystalline Bi-Sb alloys

We report on a study of electronic transport in semimetallic Bi 0.96Sb0.04. At zero field, the system is a very dilute Fermi liquid displaying a T2 resistivity with an enhanced prefactor. Quantum oscillations in resistivity as well as in Hall, Nernst, and Seebeck responses of the system are detectable and their period quantifies the shrinking of the Fermi surface with antimony doping. For a field along the trigonal axis, the quantum limit was found to occur at a field as low as 3 T. An ultraquantum anomaly at twice this field was detected in both charge transport and Nernst response. Its origin appears to lie beyond the one-particle picture and linked to unidentified many-body effects. © 2008 The American Physical Society.

Journal	EPL
Publisher	Institute of Physics Publishing
ISSN	0295-5075