Substitution effect on the thermoelectric properties of p-type half-Heusler compounds: ErNi1−xPdxSb

The authors conducted thermoelectric characterizations on polycrystalline samples of ErNi1−xPdxSb (x=0.25, 0.5, and 0.75) to develop p-type half-Heusler thermoelectric materials. All samples prepared here indicated positive Seebeck coefficient (S) values. Variations of the electrical resistivity (ρ) and the S of ErNi1−xPdxSb with x were examined by collecting the carrier concentration, mobility, and density-of-state effective mass. The thermal conductivities (κ) of ErNi1−xPdxSb were approximately one-half of those of ErNiSb and ErPdSb, mainly due to an alloy scattering effect between Ni and Pd. With the alloying of ErNiSb and ErPdSb, the thermoelectric figure of merit ZT (=S2T∕ρκ) was enhanced; the maximum ZT value was 0.29 at 650K, obtained in the composition ErNi0.5Pd0.5Sb.