Preparation and Thermoelectric Properties of Zr1-xTixNiSn0.975Sb0.025 Half-Heusler Alloys

Zr1-xTixNiSn0.975Sb0.025 (x=0, 0.15, 0.25, 0.5) half-Heusler thermoelectric materials have been prepared by levitation melt, melt spinning and hot pressing. X-ray diffraction analysis and scanning electron microscopy observation showed that nearly single phase half-Heusler compounds were obtained for the levitation-melted ingots. The effects of Ti substitution and grain refinement by melt spinning have been studied. It is found that both the Ti substitution on the Zr site and the grain refinement can reduce the lattice thermal conductivity and total thermal conductivity. The maximum figure of merit ZT value achieved is about 0.47, which is comparable with the previously reported value of ～0.5 for Zr0.5Ti0.5NiSn.