Synthesis and magnetic characterization of Mn and Co spinel ferrite-silica nanoparticles with tunable magnetic core

A method for coating silica on CoFe2O4 and MnFe2O4 spinel ferrite nanoparticles has been developed by using a reverse micelle microemulsion approach. The ability to controllably synthesize magnetic nanoparticulate cores independent of encapsulation provides great flexibility in tuning the magnetic properties of this magnetic nanocomposite system by controlling the magnetic properties of nanoparticulate cores. For these spinel ferrite nanoparticles, the saturation and remnant magnetizations decrease upon silica coating. The coercivity of silica-coated CoFe2O4 nanoparticles; does not show any change after coating, while the coercivity of MnFe2O4 nanoparticles decreases by 10% after they have been coated with silica.