Effect of aluminum and copper addition to the thermoelectric properties of FeSi2 sintered in the atmosphere

Abstract

Thermoelectric materials with composition of Fe0.92Mn 0.08Si2.1 + X mass% CU+ Y mass% Al (0 ≤ X, Y ≤ 5) were produced by sintering in air, and their thermoelectric properties and structures were examined. The samples showed fairly good thermoelectric properties. Moreover they were covered with an oxidation resistance layer. The samples without addition of Cu and/or Al did not show any effective thermoelectric properties. In the case of copper addition, the thermoelectric power of the copper added sample was approximately 75% of the sample prepared in a vacuum, while the resistivity was drastically increased. The oxidation of the copper added samples was much less than that without copper. In the case of 2 mass% or more aluminum addition, a silicon oxide layer was formed on the surface of the samples. The oxide layer had much more dense and smooth surface, which was confirmed by an optical microscope and a scanning electron microscope (SEM). The samples, which were added both copper and more than 2 mass% aluminum, showed about 80% of thermoelectric power of the samples prepared in a vacuum. ©2009 The Thermoelectrics Society of Japan.