Study of preparation and magnetic properties of silica-coated cobalt ferrite nanocomposites
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The structure and the magnetic properties of silica-coated cobalt ferrite nanoparticles (80 wt% CoFe2O4), prepared by sol–gel method and submitted to thermal treatments in the range 800–1,000 °C, were investigated through XRD, FT-IR, TEM and VSM. The effects of thermal treatment temperatures on the structure and magnetic properties of nanoparticles were examined. A silica shell thickness of about 5 nm was synthesized on top of cobalt ferrite nanoparticles. The non-crystalline silica confines the growth of cobalt ferrite nanoparticles, i.e., the particle sizes are almost independent of the thermal treatment. Saturation magnetization (Ms) was decreased slightly and coercivity (Hc) was increased, when the non-crystalline silica was coated on the surface of cobalt ferrite nanoparticles.
KeywordsFerrite Crystallite Size CoFe2O4 Silica Shell CoFe2O4 Nanoparticles
This work is supported by the National Natural Science Foundation of China (NSFC) (Grant No. 50372025 and 50572033).
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