A NOVEL INTERPRETATION OF THE COMPLEX PERMEABILITY IN POLYCRYSTALLINE FERRITES

The complex permeability in polycrystalline ferrites is known to depend strongly on the size of the grains. A model has recently been developed to account for this, which considers a microstructure of crystalline ferrite grains with an intrinsic complex permeability mu-i, each surrounded by thin, non-magnetic grain boundaries. It is demonstrated in the present paper that our model successfully accounts for the observation that in polycrystals the temperature variation of the initial permeability around the secondary maximum is observed to decrease with decreasing grain size. Further consequences of our model relating to such technologically important parameters as the temperature factor and the loss factor are also discussed.