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

Abstract Recent discovery of new p‐type Ta_1‐xTi_xFeSb‐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‐xTi_xFeSb (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_0.88Ti_0.12FeSb (x=0.12) can be further increased by 10% once the carrier concentration is appropriately tuned.