Effect of substitutions on the thermoelectric figure of merit of half-Heusler phases at 800°C

The merit of thermally stable MNiSn ( M = Ti , Zr, Hf) half-Heusler phases, as n -type thermoelectric materials, for high-temperature power generation has been examined. Sb doping at the Sn site is shown to increase both the figure of merit, Z T , and the temperature at which Z T is maximized. The benefits of increased alloying at the M and Ni sites, on the thermal conductivity and thermoelectric transport properties, have also been investigated. The thermoelectric figure of merit, Z T ∼ 0.8 at T ∼ 800 ° C , for select Sb-doped MNiSn alloys was found to meet or exceed the industry benchmark set by SiGe alloys.