Thermoelectric Transport Properties of Double-Filling InxLa0.25Co4Sb12 Skutterudite Materials

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.

Automated summary

In this study, filled-skutterudite materials InxLa0.25Co4Sb12 were synthesized using mechanical alloying and spark plasma sintering techniques. The presence of InSb nanoinclusions was found to significantly reduce the electrical resistivity and lattice thermal conductivity, leading to an enhancement in the dimensionless figure-of-merit (ZT).