Influence of ${\hbox {Fe}}_{2}{\hbox {O}}_{3}$ Stoichiometry on Initial Permeability and Temperature Dependence of Core Loss in MnZn Ferrites

We investigated the relationship between magnetic properties of MnZn ferrites and Fe₂O₃ stoichiometry by measuring magnetic properties, electrical resistivity, and density. We used a scanning electron microscope to observe the fractured surface of sintered samples. MnZn ferrites were prepared by adapting the conventional ceramic technique. Toroidal cores were sintered at 1355degC for 4 h with 4% oxygen. The results show that the initial permeability and power losses of MnZn ferrites strongly depend on the content of Fe₂O₃. And there is an obvious secondary maximum peak in the curve of mu_i versus T at about 100degC. The initial permeability mu_i reaches a maximum value and the power loss is lowest over a wide temperature ranging from 20degC to 180degC when the content of Fe₂O₃ is 52.5 mol%.