Abstract
Filled-skutterudite materials are promising candidates for thermoelectric applications in the intermediate-temperature range to recover waste heat. In this work, mechanical alloying and spark plasma sintering (SPS) techniques were used to consolidate double-filling InxLa0.25Co4Sb12 (x = 0, 0.1, 0.3, 0.5) samples. X-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray spectroscopy were used to analyze the microstructure of the InxLa0.25Co4Sb12 SPS-ed samples. The microstructure results revealed the main phase of the CoSb3 skutterudite structure with a small amount of InSb and CoSb2 attributed to secondary phases. Electrical resistivity remarkably decreased to 9.7 mu omega m at room temperature for the In0.5La0.25Co4Sb12 sample, mainly due to the effective impurity of the InSb nanoinclusions. Moreover, the InSb nanoinclusions yielded a substantial depression in lattice thermal conductivity due to phonon scattering. The reduction in lattice thermal conductivity was approximately 62% for the In0.5La0.25Co4Sb12 sample compared with the La0.25Co4Sb12 sample, resulting in a remarkable enhancement in the dimensionless figure-of-merit (ZT) of 1.25.