Microstructure, Electrical, and Magnetic Properties of ZrO $_{2}$ Added MnZn Ferrites

We investigated the influence of ZrO₂ on the microstructure and electromagnetic properties of MnZn ferrites by characterizing fracture surface micrographs, magnetic properties, and dc resistivity. Powders of Mn _0.68Zn _0.25Fe _2.07O ₄ composition were prepared by the conventional ceramic technique. Toroidal cores were sintered at 1350degC for 4 h in N₂/O₂ atmosphere with 4% oxygen. The results show that the lattice constant and average grain size increase with ZrO₂ concentration, but excessive ZrO ₂ concentration will result in exaggerated grain growth and porosity increase. The dc resistivity, activation energy, saturation magnetic flux density, and initial magnetic permeability increase monotonically when the ZrO₂ concentration is not more than 0.04 wt% and then decrease with further increase of ZrO₂ concentration. On the other hand, the porosity, drift mobility, resonance frequency, and core loss decrease initially and then increase with the increase of ZrO₂ concentration.