Synthesis and thermoelectric properties of double-filled skutterudites CeyYb0.5−yFe1.5Co2.5Sb12

Ce–Yb double-filled skutterudites Ce0.5−yYbyFe1.5Co2.5Sb12 (y = 0.1, 0.2, 0.4 and 0.5) were synthesized by a melting method with subsequent annealing. The thermal conductivity, electrical conductivity and Seebeck coefficient were measured from room temperature up to 773 K. The thermal conductivities of all the double-filled skutterudites were found to be lower than the Yb single-filled skutterudites. An enhancement in the dimensionless thermoelectric figure of merit ZT was also observed in all the double-filled skutterudites as compared to the Yb single-filled skutterudite. Ce0.3Yb0.2Fe1.5Co2.5Sb12 has the highest dimensionless figure of merit ZT of 0.32 at 723 K, which is 55% higher than the Yb single-filled skutterudite at the same temperature.