Preparation and thermoelectric properties of some phosphide skutterudite compounds

Thermoelectric properties of CoP₃ and CeFe₄P₁₂ have been measured. These compounds were synthesized by a flux technique using Sn as the solvent. The samples were characterized by x-ray diffractometry and electron microprobe analyses. The Seebeck coefficient, the electrical resistivity, the Hall effect, and the thermal conductivity were measured over a wide range of temperatures. The results indicate that CoP₃ and CeFe₄P₁₂ are semiconductors, in agreement with theoretical predictions. The thermal conductivity of CeFe₄P₁₂ is about 10 times larger than that for CeFe₄Sb₁₂ which is primarily due to both reduced motion of the Ce ions in smaller voids and lower hole-phonon scattering. The results are analyzed and discussed to provide guidelines for optimization of the thermoelectric properties of these materials.