Effect of Fe substitution on the thermoelectric transport properties of CoSb3-based Skutterudite compound

Co4−xFexSb12 (x ≤ 1) substituted Skutterudites have been synthesized by mechanical alloying–hot pressing method, their thermoelectric properties have been investigated and phonon scattering mechanism discussed in this paper. There is a maximal Fe substitution at about x = 0.65 and all samples exhibit p-type behavior. Both the electrical resistivity and Seebeck coefficient of the substituted Skutterudite decrease with increasing Fe content, and the thermal conductivity is lowered dramatically with Fe substitution. The resultant dimensionless figure of merit ZT increases with Fe substitution and a maximal ZT is obtained as 0.32 for Co3.35Fe0.65Sb12 at 773 K. Analysis on thermal transport mechanism reveals that disorder scattering is not the main reason for decrease of the lattice thermal conductivity with Fe substitution, while carrier–phonon scattering could not be ignored in these heavily doped semiconductors and some other mechanism may exist.