Phase-Controlled Synthesis of Iron Silicide (Fe₃Si and FeSi₂) Nanoparticles in Solution

In this study, a high-temperature reduction method is developed to prepare iron silicide nanoparticles in solution phase. The synthesis applies a reaction of silicon tetrachloride with iron pentacarbonyl in the presence of 1,2-hexadecanediol to form iron silicide nanoparticles. Under iron-rich synthetic conditions, superparamagnetic Fe 3 Si nanoparticles form. The saturation magnetization of Fe 3 Si nanoparticles has been found to be 60 emu/g by superconducting quantum interference device (SQUID) magnetometry technique. The value is close to that of iron oxide (Fe 3 O 4 ) nanoparticles but less than that of iron nanoparticles. When silicon-rich conditions are used, mainly β-FeSi 2 nanoparticles form. The nanoparticle size, size distribution, and crystallinity are characterized by transmission electron microscopy (TEM), electron diffraction (ED), X-ray diffraction (XRD), and atomic force microscopy (AFM).