Synthesis, structure and magnetic properties of SiO2-coated Fe nanocapsules

SiO2-coated Fe nanocapsules were synthesized by arc-discharge method using micron-sized powders as the raw materials. It was shown that most of nanocapsules were spherical with a “core/shell” type structure. The shell was an amorphous SiO2 with around 10–20 nm in thickness and the core was a ferromagnetic Fe. The unique morphologies of the nanocapsules implied that the growth was governed by an extended mechanism of the vapor–liquid–solid (VLS) with the existence of stoichiometric oxygen. The Fe core was in a BCC structure and may play as a catalyst. This kind of “core/shell” type nano-composite can involve multi-loss mechanisms for electromagnetic wave absorption and open a way to synthesizing serials of new “core/shell” (metallic/dielectric) type nano-composites.