Microstructure and Magnetic Property of Polycrystalline ZiZn Ferrite

NiZn ferrite groups of a constant grain size with the relative density ranging from 50 to 98% and the groups of a constant density with the grain size from 0.6 to 80μ were fabricated by the hot-pressing and the ordinary firing method. For each group, initial permeability and BH characteristics were systematically measured as a function of density and grain size.The results obtained are summerized as follows:(1) The relation between the density and permeability follows the logarithmic mixing rule.(2) The maximum initial permeability increases linearly with increase of the grain size.(3) Coercive force is in the linear relation with the reciprocal of grain size, but is almost independent of density.(4) Remanent magnetic flux density depends strongly on density, but is almost independent of grain size.