Kinetics and magnetic properties of sol-gel derived NiZn ferrite-SiO_2 composites

摘要

NiZn ferrite―SiO_2 composites are synthesized by a sol-gel method. The chemical and structural changes of gels during heat treatment are analyzed using DTA, infrared spectra (IR) spectra and XRD. Several kinetic models in predicting the formation of ferrite are assessed. The result indicates that the rate of ferrite formation in sol-gel derived composites is best represented by Blum and Li's equation, dx/dt=(k―x)/t. Variation of initial permeability with composition is discussed and possible magnetic mechanisms are investigated. Grain size and the continuity of magnetic circuit are the main factors to determine magnetic properties of ferrite composite materials.