Predicting the band structure, transport properties, electronic fitness function and effective mass of PdTiSn indirect band-gap half-Heusler semiconductor

Abstract

This work presents the report of density functional theory investigations into PdTiSn Half Heusler alloy using Boltzmann theory of BoltzTraP codes as incorporated in quantum ESPRESSO package with plane-wave pseudo-potentials to investigate the electronic band structure and transport properties of this compound. Also, transport effective mass and electronic fitness function for this system were computed from results of Boltzmann transport theory based calculations via transM code. A probe into the obtained band structure, classified PdTiSn as an indirect semiconductor with estimated band gap of 0.47 eV. This material possessed notable high conductivity values at carrier concentration (CC) of 1022 cm−3 in temperature range of 100–800 K. It was observed that within the investigated temperature range, for n- and p-types, there were sharp decreases in Seebeck coefficients, which later increased for the n-type. Power factors per relaxation time for both the n- and p-types increased as temperature increases with peak values recorded at 800 K beyond 1021 cm−3 CC and is higher for the p-type. The calculated electronic fitness function has a maximum value of 7 × 1020 W5/3m-s−1/3K−2, where the electron's and hole's concentrations are zero. This material also exhibited light effective mass, this responsible for its higher conductivity. The thermoelectric properties, effective mass and electron fitness function for pure PdTiSn half Heusler alloy are extensively reported here. The results of this study predict PdTiSn as a p-type semiconductor, which will provide better thermoelectric performance.