Thermopower of an Oxide-Alloy Composite System Obtained by In Situ Carbothermal Synthesis

Abstract

A new multiphase thermoelectric material, composed of La(Fe 0.6 Co 0.4 )O 3 oxide and FeCo alloy, has been synthesized by in situ carbothermal synthesis. Polycrystalline samples were prepared by the standard solid-state reaction method using starting materials of La(Fe 0.6 Co 0.4 )O 3 , Co 3 O 4 , Fe 3 O 4 , and carbon. The structure study showed that the resultant sample was a composite system of an oxide and alloy. It was found that the FeCo alloy in the samples was synthesized by the carbothermal reduction method from the starting oxide materials of Co 3 O 4 and Fe 3 O 4 . The composite system exhibited metallic behavior in the temperature dependences of the electrical resistivity and the negative Seebeck coefficient. The Seebeck coefficient values of this composite system were about four times larger than those of the FeCo alloys alone, and the electrical resistivity remained as low as that of the FeCo alloys alone. As a result, the power factor of this composite system was evidently improved compared with both the La(Fe 0.6 Co 0.4 )O 3 oxide and the FeCo alloys.