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

摘要

The Mn-Zn ferrite precursor prepared by the hydrometailurgical 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 CaCO_3/SiO_2 can significantly improve the frequency stability of permeability by creating a high resistivity grain-boundary; Bi_2O_3 can promote the ferrite grain growth and affect microstructure development; proper amount of SnO_2 and V_2O_5 can increase the initial permeability effectively, while excessive SnO_2/V_2O_5 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.% CaCO_3,0.03 wt.% Bi_2O_3,0.02 wt.% V_2O_5 and 0.02 wt.% SnO_2 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.