Thermoelectric performance of half-Heusler compounds TiNiSn and TiCoSb

The electronic structures of half-Heusler compounds TiNiSn and TiCoSb are investigated by using the full-potential linearized augmented plane-wave method. When the spin-orbital coupling is included in the calculations, there is only a slight change in the energy band structures. The transport coefficients (Seebeck coefficient, electrical conductivity, and power factor) are then calculated within the Boltzmann theory, and further evaluated as a function of chemical potential assuming a rigid band picture. Our calculations offer a valuable insight on how to improve the thermoelectric performance of these two compounds.