Effects of Ti Doping on TaFeSb Half‐Heuslers Estimated by a Single Parabolic Band Model

Abstract Recent discovery of new p ‐type Ta 1‐ x Ti x FeSb‐based half‐Heusler thermoelectric alloy has drawn much attention due to its high thermoelectric performance, zT of ∼1.52 near 970 K. However, the electronic band parameters of TaFeSb nor Ti‐doped TaFeSb have not been studied so far. Here we report the band parameters of Ta 1‐ x Ti x FeSb ( x =0–0.16) calculated by the Single Parabolic Band model. Ti doping ( x =0.12) both increases the density‐of‐states effective mass and non‐degenerate mobility by 27 and 29 times compared to those of the pristine TaFeSb ( x =0). This simultaneous increase results in weighted mobility improvement by a factor of 4000 with Ti doping of x =0.12. Based on the estimated weighted mobility and the lattice thermal conductivity, the 300 K zT of Ta 0.88 Ti 0.12 FeSb ( x =0.12) can be further increased by 10% once the carrier concentration is appropriately tuned.