Electronic structure and thermoelectric properties of half-Heusler alloys NiTZ

We investigated the electronic and thermoelectric properties of half-Heusler alloys NiTZ (T = Sc and Ti; Z = P, As, Sn, and Sb) having an 18 valence electron count. Calculations were performed by means of density functional theory and the Boltzmann transport equation with constant relaxation time approximation, validated by NiTiSn. The chosen half-Heuslers were found to be indirect bandgap semiconductors, and the lattice thermal conductivity was comparable with the state-of-the-art thermoelectric materials. The estimated power factor for NiScP, NiScAs, and NiScSb revealed that their thermoelectric performance can be enhanced by an appropriate doping rate. The value of ZT found for NiScP, NiScAs, and NiScSb is 0.46, 0.35, and 0.29, respectively, at 1200 K.