Thermoelectric properties of the filled skutterudite in the Ce-Fe-Co-Sb-Sn system

Ribbons with Ce(6-x)/3Fe6Co2Sb24-xSnx compositions were fabricated by spin-casting, and discs were prepared by sintering the powders. The samples were investigated by X-ray diffraction, transmission electron microscopic observation, energy dispersive X-ray (EDX) analysis and measurements of the Seebeck coefficient, electrical conductivity, Hall coefficient, and thermal conductivity at room temperature. Tin addition is effective to form the skutterudite rapidly without annealing. The skutterudite exists as a single phase for x <= 0.25, while if coexists with the FeSb2 phase and Sb or beta-SbSn phase for x >= 0.5. The electrical conductivity, carrier mobility, and thermal conductivity increase with increasing x. The Seebeck coefficient, power factor, and dimensionless figure of merit increase, reach maxima and then decrease as x increases. The phases coexisted with the skutterudite phase are effective to improve the thermoelectric properties.