Thermoelectric properties of the Skutterudite-related phase CoSn 1.5Te1.5

A new skutterudite-related phase CoSn_1.5Te_1.5 was prepared. This new phase is one of a large family of skutterudites which have shown a good potential for thermoelectric applications. Polycrystalline samples were prepared by the spark plasma sintering method and were characterized by x-ray diffractometry. CoSn_1.5Te_1.5 has a cubic lattice, space group Im3. With a=9.121 Å. The electrical conductivity, the Seebeck coefficient, and the thermal conductivity were measured over the temperature range 300-900 K. The temperature dependence of the electrical conductivity revealed that CoSn_1.5Te_1.5 was a semiconductor with a band gap of 0.7 eV. The electrical conductivity increased by doping with Ni. Large Seebeck coefficients up to -450 μV/K were obtained on the n-type undoped samples. The thermal conductivity of CoSn_1.5Te_1.5 was substantially lower than that of the binary isostructural compounds CoSb₃ and IrSb₃. The potential of this material for thermoelectric applications is discussed