Enhanced thermoelectric figure of merit of Co4Sb11.5Te0.5 via a two-pronged strategy combining grain refinement and nano-inclusions

In this study, a strategy combining grain refinement and nano-inclusion is presented to enhance the thermoelectric figure of merit (ZT) of Co4Sb11.5Te0.5. Homogeneously dispersed nano-TiN particles are introduced into the different grain-size skutterudite compounds Co4Sb11.5Te0.5 through ball milling and spark plasma sintering. The phase purity, microstructures, and thermoelectric properties of all the samples are characterized. The results prove that the sample consisted of the finest grain (∼220 nm) Co4Sb11.5Te0.5 and nano-TiN demonstrates a much lower thermal conductivity of 2.34 Wm−1 K−1 at room temperature and a highest ZT value of 1.07 at 800 K. Furthermore, annealing this sample at 500 °C for 50 h shows minor changes in structure and ZT value, indicating an excellent thermal stability.