Effect of samarium filling on the lattice thermal conductivity of skutterudite materials

Sm-filled skutterudites SmxCo4Sb12 (x=0.1, 0.2, 0.5) were synthesized via high pressure and high temperature (HPHT) technique. The temperature dependences of electrical resistivity, Seebeck coefficient and thermal conductivity were measured on these compounds in the range of 300–723 K. All samples showed n-type conduction. The thermal conductivity of SmxCo4Sb12 was significantly depressed as compared to unfilled CoSb3. It was believed that Sm atoms “rattled” in the voids of structure and substantially affected the phonon propagation through the lattice. The dimensionless thermoelectric figure of merit, ZT, increased with increasing temperature and reached a maximum value of 0.81 for Sm0.5Co4Sb12 at 723 K.