Effect of partial La filling on high-temperature thermoelectric properties of IrSb₃-based skutterudite compounds

We previously reported that IrSb₃-based ternary compounds showed good electrical properties and that relatively high thermal conductivity prevented the enhancement of the efficiency of these compounds.¹ Recently, we have investigated the high-temperature thermoelectric properties of La-filled IrSb₃-based skutterudite compounds from the viewpoint of a decrease in lattice thermal conductivity. It has been confirmed from Rietveld analysis that the La ions are partially placed in cages of La-filled and Ge-charge-compensated La_YIr₄Ge_3YSb _12-3Y compounds and 53% filling of La ions is obtained. Owing to the rattling effect of La ions in cages, the La-filled and Ge-charge-compensated La_YIr₄Ge_3YSb_12-3Y compounds exhibit tremendously decreased lattice thermal conductivity at room temperature, 1.8 W/mK from 10.2 W/mK of binary IrSb₃.