Ab Initio Prediction of Large Thermoelectric Effect in Distorted Heusler Alloy Ti-Fe-Sb Compound

TL;DR

This study uses first-principles calculations to predict that the distorted Heusler alloy TiFe$_{1.5}$Sb exhibits a high thermoelectric figure of merit due to its low thermal conductivity and high Seebeck coefficient, indicating its potential for thermoelectric applications.

Contribution

The paper provides the first ab initio prediction of large thermoelectric effects in TiFe$_{1.5}$Sb, highlighting its stability and promising thermoelectric properties.

Findings

Low lattice thermal conductivity of 0.703 W/mK at 300 K.

High Seebeck coefficient of 359.4 μV/K at 300 K.

High thermoelectric figure of merit (ZT) of 0.88 at 300 K and 0.91 at 500 K.

Abstract

The thermoelectric figure of merit of the Heusler alloy TiFe$_{1.5}$Sb was investigated by first-principles calculations of lattice thermal conductivity. The electronic thermal conductivity, electrical conductivity, and Seebeck coefficient are calculated by semi-classical Boltzmann transport theory. TiFe$_{1.5}$Sb was found to be thermally and dynamically stable, as confirmed by its phonon dispersion. Additionally, the small phonon band gap between acoustic and optical modes enhances phonon scattering, leading to a low lattice thermal conductivity of 0.703 W/mK at 300 K. Our study also reveals that TiFe$_{1.5}$Sb is a non-magnetic semiconductor. Notably, it demonstrates a significant longitudinal thermoelectric effect, with a Seebeck coefficient of 359.4 $\mu$V/K at 300 K. The combination of low lattice thermal conductivity and a high Seebeck coefficient results in a high thermoelectric figure of merit (ZT) of 0.88 and 0.91 at 300 K and 500 K, respectively. These findings highlight the considerable potential of TiFe$_{1.5}$Sb as a promising material for thermoelectric device applications.