Low temperature thermoelectric properties of Ca/sub x/Co/sub 4/Sb/sub 12/ skutterudites

Electrical resistivity, thermoelectric power, thermal conductivity, and dimensionless figure of merit of the partially filled skutterudites CaxCo4Sb12, with x = 0, 0.03, 0.05, 0.08, and 0.20, have been studied in the low temperature range, from 4.2 to 300 K. The compounds have been prepared by a powder metallurgy route. We find that the insertion of Ca in the voids of the skutterudite structure has a dramatic effect on all the transport properties. Qualitative analysis of the physical properties was realized and the results are discussed as a function of the Ca filling fraction and compared to data obtained with other CoSb3 partially filled skutterudites.