Low-temperature synthesis of β-FeSi₂ powder using a sodium melt

β-FeSi₂ powder was prepared by heating a mixture of Fe and Si powders with Fe/Si molar ratios of 1:2.25-2.50 in a Na melt at 773-1073 K for 1.5-24 h under an Ar atmosphere, while no β-FeSi₂ was obtained at 1073 K for 24 h without Na. The β-FeSi₂ phase was identified by powder X-ray diffraction. The primary and secondary grain sizes of β-FeSi₂ powder observed by transmission electron microscopy and scanning electron microscopy were 100-400 nm and 5-80 μm, respectively.