Thermal transport properties of IrSbSe

TL;DR

This study investigates the thermal transport properties of IrSbSe, revealing polaronic and variable-range hopping conduction mechanisms, low thermal conductivity, and high defect tolerance, with implications for thermoelectric applications.

Contribution

It provides the first detailed analysis of IrSbSe's thermal transport, highlighting its conduction mechanisms, low thermal conductivity, and defect tolerance, suggesting potential for thermoelectric improvements.

Findings

IrSbSe exhibits polaronic and variable-range hopping conduction.

Thermal conductivity is approximately 1.65 W/K·m at 100 K.

High defect tolerance suggests potential for enhanced thermoelectric performance.

Abstract

We report a thermal transport study of IrSbSe, which crystallizes in a noncentrosymmetric cubic structure with the $P2_13$ space group and shows a narrow-gap semiconducting behavior. The large discrepancy between the activation energy for conductivity [$E_\rho$ = 128(2) meV] and for thermopower [$E_S$ = 17.7(9) meV] from 200 to 300 K indicates the polaronic transport mechanism. Electrical resistivity varies as $exp(T_0/T)^{1/4}$ and thermopower varies as $T^{1/2}$ at low temperatures, indicating that it evolves into the Mott's variable-range hopping dominant conduction with decreasing temperature. IrSbSe shows relatively low value of thermal conductivity ($\sim$ 1.65 W/K$\cdot$m) and thermopower of about 0.24 mV/K around 100 K, yet poor electrical conductivity. On the other hand, high vacancy defect concentration on both Ir and Sb atomic sites of up to 15\%, suggests high defect tolerance and points to possibility of future improvement of carrier density by chemical substitution or defect optimization.