Unveiling the Thermoelectric Properties of Some Bismuth Based Half Heuslers: A First-Principles Perspective

Half Heusler (hH) materials are considered potential options for thermoelectric technologies, offering potential solutions to the growing global energy demand. This study investigates the electronic, lattice dynamics, mechanical, and thermoelectric properties of 18 VEC Bismuth based hH’s NbRuBi, NbOsBi, and TaFeBi using density functional theory, and semiclassical Boltzmann transport theory. Due to the presence of heavier element bismuth, all calculations are performed with considering SOC. The compounds under study are thermodynamically, dynamically and mechanically stable. They exhibit semiconducting behavior with indirect band gaps of 0.38 eV, 0.27 eV, and 0.86 for NbRuBi, NbOsBi, and TaFeBi respectively. The charge transport parameters w.r.to chemical potential was performed for different temperatures. At 1100 K, the maximum power factors (P F ) for p-type carriers are found to be 73.59 μW/cmK2 for NbOsBi, 66.70 μW/cmK2 for NbRuBi, and 69.70 μW/cmK2 for TaFeBi. The room-temperature lattice thermal conductivity (κl) are found to be less than 12 Wm−1K−1. The combination of high PF and low κl in these compounds results an optimal p-type zT > 1, with NbRuBi achieving the highest value of 1.48 at 1100 K. Our study highlights that these materials have potential for high-temperature thermoelectric applications and may attract experimental interest.