Effects of Cobalt Substitution for Fe on the Thermoelectric Properties of p-Type CeFe4-xCoxSb12 Skutterudites

-Type CeFe4- Co Sb-12 ( = 0 to 0.5) compounds with different Co contents have been synthesized by a melt-quench-anneal-spark plasma sintering method. The substitution of iron by cobalt has a significant impact on the thermoelectric transport properties, where the electrical conductivity decreases monotonically and the Seebeck coefficient exhibits an opposite variation with increasing Co content. Overall, the power factor remains unchanged for the low-Co-content samples and gradually decreases while is larger than 0.2. Co substitution markedly suppresses the carrier thermal conductivity due to the declining electrical conductivity, but it has no significant influence on the lattice thermal conductivity, thereby lowering the total thermal conductivity. When combining high power factor with low thermal conductivity, the samples with Co substitution show enhanced thermoelectric performance compared with that of the Co-free sample. The maximum reaches 0.9 at 800 K for the CeFe3.8Co0.2Sb12 sample, making it a promising candidate for intermediate-temperature power generation.