Synthesis and thermoelectric properties of Ce z Fe4-x Co x Sb12 skutterudites

P-type Ce-filled skutterudites Ce (z) Fe4-x Co (x) Sb-12 (z = 0.3-1, x = 1-3) were prepared, and their thermoelectric properties were examined at temperatures between 500 K and 800 K. Specimens were synthesized by encapsulated melting at 1323 K for 10 h and were hot pressed after annealing at 873 K for 24 h. Stable skutterudite phases could be obtained by the incorporation of Ce filling and charge compensation with Co for Fe. The electrical conductivity decreased slightly with increasing temperature and Co content. The Seebeck coefficient had positive values (p-type conductivity), increased with increasing temperature until a specific temperature, and then decreased thereafter. The thermal conductivity decreased through the further lattice scattering induced by substituting Co at Fe sites and by Ce filling. The thermoelectric performance of Fe-rich skutterudites was superior to that of Co-rich skutterudites. A dimensionless figure of merit of ZT (max) = 0.7 was achieved at 823 K for CeFe4Sb12.