Influence of additives on the magnetic properties, microstructure and densification of Mn–Zn soft ferrites

Mn–Zn ferrites are very important ferromagnetic ceramics and widely used for high-frequency magnetic core materials because they have low power loss and high initial permeability up to several MHz range. Magnetic properties of Mn–Zn ferrites are strongly dependent on the processing. Small amounts of additives can greatly affect the properties of ferrites. Additives can be divided into three categories. The first group consists of additives that segregates to the grain boundaries and affect the grain-boundary resistivity. The second group consists of additives that affect microstructure development. The third group consists of additives that are dissolved into the grains and alter the magnetic properties. With expanded applications of soft magnetic materials expected in the future, it is appropriate to review the influence of additives (SiO2, CaO, V2O5, Bi2O3, MoO3, Nb2O5 and TiO2) on the magnetic properties and microstructure of these materials.