Antimonides with the Half-Heusler Structure: New Thermoelectric Materials

The thermoelectric properties near ambient temperature of half-Heusler alloys based on LnPdSb, where Ln=Ho, Er, and Dy, are reported. The Seebeck coefficients are large, between 60 and 250 m V/K. The dominant carriers in the electrical conduction are holes. The resistivities range between 0.6 and 20 mOMEGAcm. Thermal conductivities are between approximately 5.0 and 3.5W mK at 300K, and are smallest in intentionally disordered materials. The highest ambient temperature ZT obtained is 0.06. Band structure calculations are presented for the non-magnetic analog, LuPdSb. It is suggested that half-Heusler alloys with 18 electrons per formula unit may represent a large class of thermoelectric materials.