Thermoelectric Properties of Half-Heusler Alloys: A First-Principles and Boltzmann Transport Approach

Abstract

Half-Heusler alloys are promising thermoelectric materials due to their favorable electrical conductivity and mechanical stability. In this work, first-principles calculations combined with Boltzmann transport theory were used to investigate the thermoelectric performance of TiCoSb-based half-Heusler alloys. Electronic structure analysis revealed an indirect band gap of 0.95 eV, suitable for thermoelectric applications. Doping with Sn at the Sb site was found to reduce lattice thermal conductivity by enhancing phonon scattering, while electrical conductivity remained stable. Seebeck coefficient calculations showed values exceeding 240 μV/K at 800 K, with the maximum power factor observed in TiCoSb₀.₉₅Sn₀.₀₅. The predicted figure of merit (ZT) reached 1.1 at 900 K, demonstrating significant enhancement over pristine alloys. These results suggest that chemical substitution is an effective strategy for optimizing the thermoelectric performance of half-Heusler compounds. The findings provide a theoretical foundation for guiding experimental synthesis of high-efficiency thermoelectric materials for waste heat recovery and sustainable energy applications.