Eco-Fabrication Process and Thermoelectric Properties of β-FeSi₂

Abstract

  The thermoelectric material β-FeSi₂ was produced by a rapid eco-process involving induction-field-activated combustion synthesis / static pseudo-isostatic compaction (IFACS/SPIC). A dense Fe-Si alloy (Fe/Si = 3/7) was synthesized by IFACS/SPIC using a powder compact of high purity Fe and Si. An induction time (5 min) of IFACS/SPIC and the annealing time (at 1123 K for 5 min) for β-transformation were extremely shorter than those of conventional synthesis. When the Fe/Si ratio of the alloy used in the eutectoid reaction α-FeSi₂→β-FeSi₂+Si was 3/7, the main annealing product was β-FeSi₂ with a small amount of free Si, and the formation of metallic ε-FeSi was prevented. The relative density and the β-transformation ratio were 95% and 96%, respectively. The thermoelectric properties of the p-type Mn-doped (Fe_2.94Mn_0.06Si₇) and the n-type Co-doped (Fe_2.94Co_0.06Si₇) products were investigated from room temperature to 1123 K.