Synthesis and Thermoelectric Properties of SnzCo3.7Ni0.3Sb12 Skutterudites

SnzCo3.7Ni0.3Sb12 skutterudites were synthesized by induction melting followed by annealing at 823 K for 120 h in a vacuum. The effects of Sn filling on the transport and the thermoelectric properties were examined at temperatures from 300 K to 700 K. The Seebeck coefficient and Hall coefficient revealed a change in electrical conduction type from n-type to p-type when the filling fraction (z) was higher, than 0.4. The temperature dependence of the electrical resistivity suggests that SnzCo3.7Ni0.3Sb12 is a highly degenerate semiconducting material. The electrical resistivity increased with increasing Sn content, which is related to the bipolar thermoelectric effect. The thermal conductivity was reduced by Sn filling, with Sn0.2Co3.7Ni0.3Sb12 showing the lowest value.