Contrasting role of bismuth doping on the thermoelectric performance of VFeSb half-Heusler

Isoelectronic heavy elemental substitutions are generally preferred for enhancing the phonon scattering in a material without deteriorating its electrical transport. In this work, we demonstrate efficacy and contrasting role of bismuth, an isoelectronic substitute antimony, thermoelectric transport structurally ordered cubic VFeSb half-Heusler. Despite limited solubility, Bi-substitution at Sb-site, was found to be effective power factor near room temperature. Alongside, synergistic lowering lattice thermal conductivity observed due point defect phonons by Bi-induced mass strain fluctuations. The electronic properties nominal compositions effects Bi-doping induced disorder were evaluated using Korringa–Kohn–Rostoker method with coherent potential approximation (KKR-CPA). A highest figure-of-merit ( zT ) ~ 0.22 478 K attained improved weighted mobility quality optimally doped 0.98 Bi 0.02 half-Heusler alloy making them prospective temperature applications. • Contrasting bismuth as isovalent antimony Sb-based High-power > 3.0 × 10 ?3 Wm ?1 ?2 Lattice reduction Bi-substituted alloys. Enhanced mobility,