Composite way to superior thermoelectric performance in In filled Co4Sb12

Filled skutterudites are known as a promising material for thermoelectric applications owing to their high zT values. The most explored approaches to reduce the thermal conductivity of CoSb₃-based materials are either filling suitable electropositive elements into the voids or the formation of composites. The two approaches were combined in this study by preparing and sintering composites of In_0.2Co₄Sb₁₂ and TiS₂ via a gas-solid reaction method. Phase formation of the composites and their surface morphologies were confirmed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). A high-power factor along with a low thermal conductivity value was observed for the 3 % TiS₂ composition resulting in a maximum zT value of 0.32 at 573 K. This is attributed to the 2D structure of the minor phase acting as effective phonon scatterers thereby reducing the thermal conductivity progressively without greatly affecting the electrical properties.