Effect of multi-additives on the microstructure and magnetic properties of high permeability Mn–Zn ferrite

The Mn–Zn ferrite precursor prepared by the hydrometallurgical route is used as raw material to prepare high permeability Mn–Zn ferrite through traditional ceramic process. The influences of three different categories of additives on the initial permeability and microstructure of Mn–Zn ferrites are investigated. Meanwhile the corresponding possible mechanisms are proposed to interpret the effect of the dopants on the magnetic properties of ferrite materials. The results show that additives CaCO3/SiO2 can significantly improve the frequency stability of permeability by creating a high resistivity grain-boundary; Bi2O3 can promote the ferrite grain growth and affect microstructure development; proper amount of SnO2 and V2O5 can increase the initial permeability effectively, while excessive SnO2/V2O5 concentration results in the abnormal grain growth and the decrease of initial permeability. Based on the doping experiment, the Mn–Zn ferrite sample doped with 0.02 wt.% CaCO3,0.03 wt.% Bi2O3, 0.02 wt.% V2O5 and 0.02 wt.% SnO2 displays higher magnetic properties including high initial permeability, wide frequency stability and temperature stability of permeability, indicating that the sample can compete with the R12K (a competitive product) made in Hengdian corporation of China.

► CaCO3/SiO2 can significantly improve the frequency stability of permeability.
► Bi2O3 can promote the grain growth and affect microstructure development.
► SnO2/V2O5 can effectively increase the initial permeability.
► The prepared Mn–Zn ferrite has advantage over R12K product.