Enhancement of high temperature thermoelectric properties of intermetallic compounds based on a Skutterudite IrSb3 and a half-Heusler TiNiSb

Phonon glass and electron crystal (PGEC) thermoelectric materials have been expected to be a new class of thermoelectric materials for high temperature applications. Among the efforts to optimize the high temperature thermoelectric properties of various PGEC thermoelectric materials, recent experimental works on the Skutterudite IrSb3 and half-Heusler TiNiSb intermetallic compounds are presented herein by which the material design concept for high energy conversion efficiency, i.e. a high figure of merit, is suggested. It is revealed that the thermoelectric efficiency of IrSb3 can be increased by the decrease of lattice thermal conductivity due to the rattling effect of La atoms filled in the structural vacancies of the Skutterudite crystal structure. In the half-Heusler TiNiSn, high temperature thermoelectric properties are improved by Hf substitution to the Ti sites by reducing lattice thermal conductivity and also by Sb doping to increase power factor. It is concluded that the proper alloy designing for controlling crystal structure and carrier concentration could enable these intermetallic compounds to exhibit a high potential for elevated temperature thermoelectric applications. (C) 2004 Elsevier Ltd. All rights reserved.