Thermoelectric Properties of Half-Heusler Type LaPdBi and GdPdBi

Abstract

The authors studied the thermoelectric properties of LaPdBi and GdPdBi half-Heusler compounds. Polycrystalline samples were prepared by a spark plasma sintering (SPS) technique, and their thermoelectric properties were measured above room temperature. The electrical resistivities of both samples show a semiconductor like behavior and are on the order of 10⁻⁶ Ω m. The estimated band gap energies of LaPdBi and GdPdBi are 0.05 and 0.07 eV, respectively. The values of the thermoelectric power are positive and decrease with increasing temperature. The thermal conductivities increase with increasing temperature because of the increase of the carrier contribution to the thermal conductivity. The maximum values of the dimensionless figure of merit ZT are 0.085 at 615 K for LaPdBi and 0.084 at 469 K for GdPdBi, respectively.