High temperature thermoelectric properties of TiNiSn-based half-Heusler compounds

A class of intermetallics of TiNiSn half-Heusler compound with MgAgAs structure type is currently of interest as a potential high temperature thermoelectric material. The ternary TiNiSn compound has showed promising thermoelectric properties, a high Seebeck coefficient and low electrical resistivity. The present study reports the effect of Hf alloying on Ti site, Pt and Pd alloying on Ni site, and Sb doping on Sn site for the optimization of thermoelectric properties of TiNiSn-based compounds. Also, to achieve a low thermal conductivity, a powder metallurgy technique is used for the fabrication of the compounds. These efforts result in the dimensionless figure of merit, ZT as 0.78 for the hot-pressed (Ti0.95Hf0.05)Ni(Sn0.99Sb0.01) sample at 770 K with a large power factor (4.1 mW/mK2), which makes these materials very attractive for potential power generation applications.