Improvement Study of Iron Disilicide Thermoelectric Materials

Abstract

Abstract : In many applications at high temperature, the semiconducting compound beta - Fe Si2 has been already proposed for power generation. The goal of this part of the study is to obtain pure semiconducting beta - Fe Si2 phase as a material of reference for thermoelectric properties. The melting of elemental Iron and Silicon powders is done at 1250 C and the transition of the metallic (alpha) to semiconducting beta phase is obtained by annealing. This classical preparation of beta - Fe Si2 was time consuming and because of the phase diagram results in the production of inhomogeneous alloys. Mechanical alloying was considered as an alternate method of producing beta - Fe Si2. This method for elaborating the compound from lower temperature must avoid the difficulties of sublimation and evaporation of the components. It also allows the optimization of beta - Fe Si2. The results of the two elaborating methods are compared by x ray diffraction measurements. These results on beta - Fe Si2 obtained by mechanical alloying, were original. This process now appears to be a reliable method to introduce amounts of dopant in the material. It must now be developed.