SnzCo4Sb11.2Te0.8 skutterudites with various filling fractions (0 ≤ z ≤ 0.4) were synthesized by encapsulated induction melting, and their thermoelectric properties were examined from 300 K to 700 K. A single δ-phase was successfully obtained by subsequent heat treatment at 773 K for 5 days. Sn-filled/Te-doped SnzCo4Sb11.2Te0.8 showed n-type conductivity at all temperatures examined, which suggests that Te atoms act as electron donors by substituting for Sb atoms. The thermal conductivity was reduced by filling and doping due to impurity-phonon scattering, and the dimensionless figure of merit (ZT) was improved. However, the ZT value decreased when the filling level was z ≥ 0.2 due to an increase in electrical resistivity and thermal conductivity.

Keywords: Thermoelectric, Skutterudite, Filling, Doping.