PREPARATION AND THERMOELECTRIC PROPERTIES OF BETA-FE1-XRUXSI2

beta-Fe1-xRuxSi2 solid solution was synthesized by solid state reaction at 1100 degrees C for 48 h and subsequent annealing at 850 degrees C for 168 h in an evacuated silica tube. Single phase solid solution was obtained in the composition range 0 less than or equal to x less than or equal to 0.1. The thermal stability range of the beta-phase is extended to higher temperature region by partial substitution of Ru atom. The thermoelectric properties of Cr or Co-doped beta-Fe1-xRuxSi2 strongly depend on the sintering conditions. The samples with optimum thermoelectric properties are obtained by high-pressure sinistering at 3 GPa and 800 degrees C for 1 h. The optimum compositions are found to be Fe0.92Ru0.05Cr0.03Si2 and Fe0.92Ru0.05Co0.03Si2 for p-type and n-type materials, respectively. The power factors (sigma alpha(2)) of these materials are higher than that of beta-FeSi2 based materials.