Effects of nano-TiO2 dispersion on thermoelectric properties of Co4Sb11.7Te0.3 composites

Nano-TiO₂/Co₄Sb_11.7Te_0.3 composites were prepared by mechanical alloying (MA) and cold isostatic pressing (CIP) process. The phase composition, microstructure, and thermoelectric properties were characterized. The diffraction spectra of all samples well corresponds to CoSb₃ skutterudite diffraction plane. TiO₂ agglomerates into irregular clusters. They locate at the grain boundaries or some are distributed on the surface of Co₄Sb_11.7Te_0.3 particles. For composites with high TiO₂ content (0.6% and 1.0% TiO₂), the phonon scattering by TiO₂ particle, pores, and small size grains can result in a remarkable reduction in thermal conductivity. The maximum value of ZT is 0.79 for sample with 0.6 wt.% TiO₂ at 700 K, which is 11% higher than that of non-dispersed sample.