Preparation And Thermoelectric Properties Of Skutterudite/InSb Nanocomposites

Thermoelectric materials are functional semiconductor materials , which can interconvert heat and electricity directly via carrier's movement. Due to its advantages of high reliability, secure, no environmental pollution and without moving parts, thermoelectric power generation and cooling devices have drawn much attention.Binary skutterudite compound, which has high Seebeck coefficient and appropriate electrical resistivity, is promising thrmoelectric materials, however, its thermal conductivity is high. In order to reduce the lattice thermal conductivity and increase the figure-of-merit, filling the structural voids with rare-earth etc. atoms to obtain filled skutterudite has been explored and proved very effective to decrease lattice thermal conductivity and enhance thermoelelctric figure of merit. In recent years,nanocomposite has become one of the hot field of thermoelectrics. A study on preparation and thermoelectric properties of skutterudite/InSb nanocomposites is carried out and presented here.N-type In_0.2Co₄Sb₁₂(InSb)_x(x=0,0.2,0.4,0.6),In_0.2Yb_0.1Co₄Sb₁₂(InSb)_y(y=0,0.2,0.4,0.6)have been successfully prepared via vacuum melting - annealing - hot pressing process. The microstructure of composites has been characterized and the effect of InSb phase on the thermoelectric properties of the nanocomposites been investigated. The results show that:By vacuum melting - isothermal annealing- hot pressing process main nanocomposites with skutterudite matrix and a small amount of InSb second-phase have been obtained. With the increasing of InSb content, thermoelectric properties of composites are increasing. Within In_0.2Co₄Sb₁₂(InSb)_x ZTmax of 0.93 has been achieved when x = 0.6, T = 673k; and within In_0.2Yb_0.1Co₄Sb₁₂(InSb)_y series, ZTmax of 0.77 has been obtained when y = 0.4, T = 573k.For the In_0.2Co₄Sb₁₂(InSb)_x series, the electrical conductivity increases and Seebeck coefficient decreases with InSb content increasing. At the same time, the lattice thermal conductivity decreases though the total thermal conductivity increases. As for the In_0.2Yb_0.1Co₄Sb₁₂(InSb)_y series, when y=0.4, 0.6, grain sizes of about 20～100nm are obtained. With increasing of InSb content, the electrical conductivity firstly increased, then after x = 0.4, the electrical conductivity begans to decrease, at the same time, the thermal conductivity increases.