High-temperature thermoelectric properties of Ti0.5(ZrHf)0.5−xNbxNi0.9Pd0.1Sn0.98Sb0.02 half-Heusler alloys

The effects of Nb substitution at the IV metal site on the thermoelectric properties of Ti0.5(ZrHf)0.5−xNbxNi0.9Pd0.1Sn0.98Sb0.02 half-Heusler alloy compounds were investigated by measuring the electrical resistivity, Hall effect, Seebeck coefficient and thermal conductivity. Changes in its microstructure were characterized using SEM and X-ray diffraction. It was shown that the substitution of Nb for TiNiSn-based alloys led to a significant reduction in the thermal conductivity due to the increase in defects and an enhancement of the electrical conductivity. The best sample reached a ZT of 0.66 at 900 K with an Nb content of x = 0.01.