Formation of Cerium-Filled Skutterudite Thermoelectric Materials Sintered from Gas-Atomized Powder

Abstract

A process for forming the Ce-filled skutterudite thermoelectric materials sintered from gas-atomized powder has been investigated. The rapidly cooled particles obtained by the Ar gas-atomizing method consist of the phases of CeFe₃CoSb₁₂ (skutterudite), FeSb₂, FeSb and Sb. The differential scanning calorimetry curve indicates that sintering proceeded through the two exothermic reactions: one due to the oxidation of Sb at low temperatures and the other due to the skutterudite phase formation from three phases of FeSb₂, FeSb and Sb at high temperatures. On the basis of these results, sintering conditions were best tuned to reduce the oxidation of Sb while ensuring the skutterudite phase formation. Consequently, it becomes possible to increase the Seebeck coefficient, and to decrease the thermal conductivity in the temperature range of 300–850 K. We consider the achievement of favorable results to be mainly attributed to a decrease in the Sb phase remaining in sintered materials.