Structural and electrical properties of β-FeSi_2 bulk materials for thermoelectric applications

摘要

P-FeSi_2 bulk materials for thermoelectric applications were prepared from high-purity (99.99 %) β-FeSi_2 powders or mixed Si and Fe powders. First, FeSi_2 powders were milled to reduce the particle size, which can improve the thermoelectric figure of merit by reducing lattice thermal conductivity. Second, they were cold pressed and then sintered by two different sintering methods: a conventional electrical furnace and a Plasma Activated Sintering (PAS) system. The bulk densities and grain sizes were decreased by ball milling of the powders starting materials. The comparison of the two sintering methods showed that, the sample density of the PAS samples was 11%- 23 % higher than that of the samples sintered in the conventional electrical furnace. Moreover, the comparison of the two types of powders, β-FeSi_2 and the mixture of Fe and Si, indicated that, β-FeSi_2 bulk crystals were formed only when β-FeSi_2 powders were used.