Thermoelectric Properties of p-Type Half-Heusler Compounds FeNb_0.9M_0.1Sb (M = Ti, Zr, Hf)

Abstract

Recently, it has been reported that Hf-substituted Fe(Nb_1−xHf_x)Sb-based p-type half-Heusler compound exhibits exceptionally high thermoelectric (TE) figure of merit zT = 1.5 at 1200 K [C. Fu et al.: Nat. Commun. 6 (2015) 8144.]. However, the effect of substitute elements on the TE properties of FeNbSb is still unclear. Here, we synthesized polycrystalline samples of Fe(Nb_0.9M_0.1)Sb (M = Ti, Zr, Hf) by arc-melting followed by spark plasma sintering, and examined their high-temperature TE properties. The Ti-substituted sample was nearly single phase while the Zr- and Hf-substituted samples contained small amounts of secondary phase. The Ti-substituted sample exhibited the best TE performance. In the present case, Ti is better substituted element than Zr and Hf for enhancement of TE properties of FeNbSb.