First-Principles Study on Mn-Doped TiFeSb Half-Heusler Thermoelectric Materials

The 8.33at% Mn-doped TiFeSb half-heusler thermoelectric materials were studied by first-principles in this paper. The space occupying of Mn atoms in Mn-doped TiFeSb system was studied according to thermodynamic stability, mechanical stability, and density of states at the Fermi level. The results show that Mn atoms would substitute Ti atoms preferentially at 8.33 at% doping amount. The electronic and phonon transport properties were calculated in TiFeSb and (Ti0.75Mn0.25)FeSb to characterize their electronic and thermal conductivity. The results indicate that Mn-doping can increase the power factor due to improving the electronic conductivity while reducing the lattice thermal conductivity. Therefore, the (Ti0.75Mn0.25)FeSb are expected to show better thermoelectric properties than TiFeSb.