Thermoelectric Properties of Ce1−xScxPd3

CePd3 is a well-known intermediate-valence compound with a peak figure of merit, ZT, of approximately 0.2 at 200 K, making it an attractive candidate for use in low-temperature thermoelectric applications. To search for improved thermoelectric behavior, we studied solid solutions of CePd3 and ScPd3. Samples of Ce1−xScxPd3 (0 < x < 0.25) were prepared via arc melting, and their resulting structural and transport properties measured. Refinement of x-ray diffraction (XRD) patterns showed single-phase materials with AuCu3 (Pm3m) structure type for all samples, with the lattice parameter decreasing linearly as a function of increasing scandium content. The Seebeck coefficient, electrical resistivity, and thermal conductivity of the samples were measured, and the corresponding ZT values determined. Although significant variation in the properties of the two CePd3 control samples was observed, the electrical resistivity and Seebeck coefficient of the substituted samples consistently decreased with increasing scandium content, while the thermal conductivity remained essentially unchanged. The net result was a decrease in both the power factor and ZT as the substitution level was increased. The variation observed in the transport properties of the substituted samples was of the same magnitude as that seen between the two controls, suggesting that these properties are generally as sensitive to Ce-site substitutions as they are to the Ce-to-Pd ratio.