Thermoelectric properties of Sn-doped CoSb3 prepared by encapsulated induction melting

Encapsulated induction melting was attempted to prepare the Sn-doped CoSb3 skutterudites (CoSb3−ySny) and their thermoelectric properties were investigated. Single phase δ-CoSb3 was successfully obtained by the encapsulated induction melting and subsequent annealing at 773 K for 24 h. However, if the Sn content (y) was larger than 0.4, δ-CoSb3 was decomposed to γ-CoSb2 and Sn. Sn atoms successfully acted as electron acceptors by substituting Sb atoms. Seebeck coefficients of the Sn-doped samples showed positive values, and electrical resistivity was remarkably reduced by Sn doping. Thermal conductivity was considerably reduced by doping due to the phonon scattering. Thermoelectric properties were improved by the appropriate post-annealing and Sn doping, and they were closely related to phase transitions and dopant activation.