Thermoelectric and thermophysical properties of TiCoSb, ZrCoSb, HfCoSb prepared by SPS

Half-Heusler compounds TiCoSb, ZrCoSb, HfCoSb were prepared by a spark plasma sintering (SPS) technique. Their thermoelectric and thermophysical properties were measured. The band gap energy estimated from the electrical resistivity becomes small in the following order: TiCoSb (0.16 and 0.40 eV), ZrCoSb (0.14 eV), HfCoSb (0.07 eV). The largest thermoelectric power is obtained as -304 mu V/K at 641 K for TiCoSb. The thermal conductivity and Debye temperature become small in the following order: TiCoSb, ZrCoSb, HfCoSb. The contribution to the thermal conductivity is mainly due to the lattice contribution. The maximum value of ZT is 0.020 at 986 K for ZrCoSb.