Magnetic properties of cobalt ferrite/SiO2 nanocomposite

Nanocrystalline cobalt ferrite dispersed in silica was prepared by mechanical alloying and subsequent heat-treatment. For Coferrite with 15 wt% silica, a high coercivity of up to 3.3 kOe and a magnetization of 68 emu/g were obtained after an optimized heat treatment (in air at 900°C). Experiments were conducted to study the optimum amount of silica required to obtain optimum magnetic properties. It was found that a small amount of 4.5 wt% silica (SiO2) allows the composite to possess good magnetic properties (coercivity of 3 kOe and saturation magnetization of 72 emu/g).