Temperature Dependence of the Permeability for MnZn Ferrites with Different Co Contents

Nanocrystalline ferrites Mn_0.4Zn_0.6-xCo_xFe₂O₄(x=0.1,0.2,0.3,0.4) were prepared by auto-combustion method.The effects of Co substitution on microstructure and magnetic properties are investigated.The ferrite powders were prepared by the self-propagating combustion synthesis method and subsequently molded and sintered at 1,150 ℃.As-synthesized ferrites powders,characterized by X-ray diffraction(XRD),had demonstrated the phase of spinel structure.The saturated magnetizations of the MnZn ferrite samples,measured by vibrating sample magnetometer(VSM),are varied with the lattice parameters,which reach the maximum values with the Co content of 0.2 in mole.The initial permeability decreases with the increase of Co content.Meanwhile,the Curie temperatures are constant.The temperature dependence of permeability showed that the temperature stability of initial permeability could be adjusted by the Co content and the sample with the Co content of 0.3 has good temperature stability.The corresponding mechanism was clarified based on the metal ion distribution.