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

Abstract

Polycrystalline Bi 1-x Sb 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 () 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 detail structural analysis of the samples and lattice parameters of polycrystalline Bi 1-x Sb 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-x Sb x alloy system has also been proposed.

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

“…32 The Bi rich semiconducting Bi 1Àx Sb x alloys discussed here possess similar band picture. 27,30 Hence, in accordance with Baraff, it is justified to assume that observed increase of E g in presence of magnetic field for Bi 0.90 Sb 0.10 and Bi 0.86 Sb 0.14 is due to the lifting of degeneracy of energy levels. 32 high as 325% has been obtained for Bi 0.86 Sb 0.14 at 15 T magnetic field without any sign of saturation.…”

“…27,28 In the present work, we report temperature and magnetic field dependent resistivity of a direct band gap (Bi 0.90 Sb 0.10 ) and an indirect band gap (Bi 0.86 Sb 0.14 ) Bi-Sb alloy. Giant non-saturating MR at low temperature has been reported in polycrystalline Bi 1Àx Sb x (x ¼ 0.10 and 0.14) samples.…”

“…27 MR is generally defined as: MR ¼ Dq q ¼ qðHÞÀqð0Þ qð0Þ , where, q(H) and q(0) are resistivities in presence and absence of magnetic field, respectively. Resistivity and MR measurement are performed on rectangular samples in a Closed Cycle Refrigerator (CCR) based 15 T magnet supplied by Cryogenic Ltd., UK in the range 5-300 K, where the standard four-probe technique with silver paste cured at room temperature is used for electrical contacts.…”

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

“…Further, it is observed that, Eg decreases with increasing temperature. It is noteworthy to mention that for pristine Bi0.88Sb0.12 alloy, Eg arises due to the gap between La and Ls bands [1,6,11]. However, impurity levels due to Sb have been postulated to exist between the La and Ls bands [18].…”

“…22) band gap at x = 0.12. These are narrow Eg semiconductors with maximum Eg of about 20 meV [3,11]. However, it should be pointed out that several groups have reported maximum Eg around x=0.15 [12,13,14].…”