Sb concentration dependent Structural and Transport properties of Polycrystalline (Bi1-xSbx)2Te3 Mixed crystal

TL;DR

This study investigates how varying Sb concentration affects the structural, thermal, and transport properties of polycrystalline (Bi1-xSbx)2Te3 mixed crystals, revealing a disorder-induced phase transition and thermoelectric performance insights.

Contribution

It provides a detailed analysis of the disorder to order transition and thermoelectric properties in (Bi1-xSbx)2Te3 crystals across different Sb concentrations.

Findings

Disorder-induced iso-structural phase transition at x=0.70.

Samples are confirmed to be p-type via Hall and thermopower measurements.

Figure of Merit (ZT) calculated, indicating thermoelectric potential.

Abstract

(Bi1-xSbx)2Te3 (x=0.60, 0.65, 0.68, 0.70, 0.75 and 0.80) mixed crystals have been synthesized by solid state reaction. In depth structural, thermal, transport and electronic properties are reported. Defect and disorder play a crucial role in structural and transport behaviour. Disorder induced iso-structural phase transition is observed at x=0.70, which is supported by the structural and transport properties data. Debye temperature has been estimated from the powder diffraction data. Differential scanning calorimetry (DSC) data confirms the glass transition in the material. Low temperature resistivity data shows Variable range hopping mechanism whereas high temperature data follows activated behaviour. Activation energy is calculated from the semiconducting region of resistivity data. Both Hall measurement and temperature dependent thermopower data (S(T)) confirms that samples are p-type in nature. Density of state effective mass has been estimated from Pisarenko relation and corroborated with resistivity data. Thermal conductivity (k) is estimated using experimentally obtained data. Figure of Merit (ZT) of the synthesized samples are calculated using resistivity, S(T) and k. Structural and transport properties are correlated, confirms the transition from disorder to order state. Defect and disorder are corroborated with structural and Thermoelectric properties of the synthesized samples.