Research On Elements’ Valence Of MnZn Ferrite

This paper expounds a relatively complete quantitative analysis method applicable to Fe²⁺and Mn³⁺of MnZn ferrite,and the stability of this method was investigated.Based on the automatic potential titration method,the influence of Fe₂O₃ and SnO₂contents on Fe²⁺and Mn³⁺concentration were investigated respectively of MnZn ferrites prepared by oxide ceramic technology,and deduced the conductive mechanism of MnZn ferrites through the measurement of power loss,initial permeability and electrical resistivity.The main conclusions in this work are listed as follows.1.Research of automatic potential titration technology.This work illustrated the titration technology completely from theory,equipment and procedure.Influence of the nitrogen concentration on the results was exploded through three samples with different Fe²⁺concentration.The results indicate 1.0².0 L/min of nitrogen gas velocity are applicable.Stability experiment shows the results of samples titrated in one day are more stable.2.Effects of Fe₂O₃ content on the Fe²⁺concentrations and magnetic properties.Magnetic properties of MnZn ferrites were measured together with the Fe²⁺and Mn³⁺concentrations for MnZn ferrite samples with the formula of（Fe₂O₃）_a（MnO）_b（ZnO）_c（52.55≤a≤53.35,38.33≥b≥37.52）.We investigated the relationship between content of Fe₂O₃,MnO and Fe²⁺concentration of MnZn ferrites,and analyzed the conductive mechanism of MnZn ferrites.The results indicates that both Fe²⁺and Mn³⁺contents increase withincreasing Fe₂O₃ content.With the increase of Fe²⁺concentration,both P_cv（min）and P_cv（20/70/100oC）decrease first and then increase over the Fe²⁺concentration of about 1.55%,butμ_i changes in the opposite way.In addition,fortheconductivemechanismofaMnZnferriteformulated Zn_?^2（10）Mn_?-x^2（10）Mn_x^3（10）Fe_y^2（10）Fe_?-y^3（10）O_4（10）?（0.1794≥α≥0.1786,0.754≥β≥0.734,0.0031≤x≤0.0040,0.051≤y≤0.070）,the influence of polaron binding energy is expected to be important at y?0.064,while Coulomb interaction between carriers is dominant when y?0.064.3.Effects of SnO₂ addition on the Fe²⁺concentrations and magnetic properties.The results indicates that with increasing SnO₂ addition from none to 0.4 wt%,Fe²⁺concentration increase from 1.755 wt%to 1.860 wt%linearly,but Mn³⁺concentration decrease from 0.091 wt%to 0.006 wt%.With the increase of Fe²⁺concentration,μ_i increases,electrical resistivity and P_evv remain unchanged,but P_cvv and P_hvv decrease.Furthermore,the bottom temperature of P_cvv moves to lower steadily.The automatic potential titration technology which is suitable for measuring Fe²⁺and Mn³⁺concentration has a lot of advantages,such as stable,accurate,easy to operate and low costs.It will be important for deeper understanding of MnZn ferrites and the development of high-grade ferrite in the future.