High-thermoelectric figure of merit realized in p-type half-Heusler compounds:: ZrCoSnxSb1-x

We studied the thermoelectric properties of heavily Sn-doped ZrCoSb half-Heusler compounds, ZrCoSnxSb1-x (x <= 0.15), to develop p-type thermoelectric materials. With increasing Sn content x, electrical resistivity decreased and the sign of the thermoelectric power changed from negative to positive. Thermal conductivity was reduced by an alloy scattering effect between Sn and Sb. A high figure of merit (ZT) was obtained: ZT = 0.45 at 958 K in ZrCoSn0.1Sb0.9. This ZT is approximately 2-fold higher than those of the p-type half-Heusler compounds that have been reported to date.