Magnetic properties of cobalt ferrite/SiO2 nanocomposite

Nanocrystalline cobalt ferrite dispersed in silica was prepared by mechanic al alloying and subsequent heat-treatment. For Co-ferrite with 15 wt% silic a, 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 degrees C). Exper iments were conducted to study the optimum amount of silica required to obt ain optimum magnetic properties. It was found that a small amount of 4.5 wt % silica (SiO2) allows the composite to possess good magnetic properties (c oercivity of .3 kOe and saturation magnetization of 72 emu/g). (C) 2000 Els evier Science S.A. All rights reserved.