Methods of Preparation and Crystal Chemistry of Ferrites

Abstract

Conventional ceramic methods for pure oxide materials can generally be applied to the processing of ferrites. Specialized techniques such as coprecipitation and hydrostatic pressing are sometimes employed. A process involving nonaqueous milling and forming additives provides dense shapes. The general formula for ferrites is MO·Fe₂O₃ (M is a divalent metallic cation). X-ray diffraction may be used to conduct unit cell and phase relation studies. Metallurgical micrographic techniques are useful in investigating grain and pore structure. A study of the solid state reaction kinetics of an equimolar mixture of MgO and Fe₂O₃ at elevated temperatures showed that the reaction was expressed by the diffusion equation (1- ³√1-.01x)² = K where x is the percentage of reaction at time t, and Kis a constant.