Electrical and thermal properties of Fe substituted double-filled BaxYbyFezCo4−zSb12 skutterudites

Fe-substituted double-filled BaxYbyFezCo4−zSb12 (x=0.1, y=0.2 and z=0.0–0.4 nominal) compounds were synthesized using a melting-annealing-spark plasma sintering (SPS) method. Their thermoelectric properties were assessed by measuring the Seebeck coefficient, electrical conductivity, thermal conductivity and the Hall coefficient. The sign of the Hall coefficient indicates that electrons are the dominant carriers in all compounds except Ba0.1Yb0.2Fe0.4Co3.6Sb12. The temperature dependence of the electrical conductivity and the carrier concentration reflect the transition from extrinsic to intrinsic behavior depending on the amount of Fe substituted for Co. Jonker and Ioffe analyses are applied to Fe-substituted double-filled BaxYbyFezCo4−zSb12 compounds in order to evaluate the range of minimum and maximum power factors achievable in n-type filled skutterudite compounds at room temperature (300 K). The predicted maximum room temperature power factor values in the range of 15–45 μW/K2 cm are comparable to experimentally reported values of n-type skutterudite compounds.