(Zr,Hf)Co(Sb,Sn) half-Heusler phases as high-temperature (>700°C) p-type thermoelectric materials

Abstract

By substituting Sn for Sb, the potential of stable (Zr,Hf)Co(Sb,Sn) half-Heusler phases, as p-type thermoelectric materials, for high-temperature power generation has been examined. Sn concentration as much as ∼20%–30% is required to realize high power factor values. Substitution of heavier Hf, which reduces the thermal conductivity (κ) via mass fluctuation scattering, nonetheless maintains high mobility. As a result, the thermoelectric figure of merit ZT, for these not-yet-optimized materials, which we found to be ZT=0.5 at 1000K (measured) and ZT=0.6 at 1100K (extrapolated), surpasses the industry benchmark for a p-type material set by SiGe alloys.