Preparation and characterization of Fe/SiO2 core/shell nanocomposites

In a simple ethanol-water system, the magnetic α-Fe nanoparticles (with an average diameter of 10–40 nm) were prepared by reduction of Fe2+ using potassium borohydride in the presence of surfactant. Then the shell was formed by hydrolysis-condensation polymerization of tetraethylorthosilicate (TEOS) on the surface of the Fe particles. The samples were characterized by XRD, TEM, SAED, TG-DSC and VSM. The results indicate that a thin film of silica is coated on the surface of Fe particles through a Si—O—Fe bond. The coated shell of silica can effectively protect the Fe cores from being oxidized.