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. (C) 2006 Elsevier B.V. All rights reserved.