Controlled atmosphere annealing of high-permeability Manganese Zinc Ferrite

The annealing of sintered (MnZn)Fe
2
O
4
in a controlled atmosphere improves the apparent electrical resistivity through the reduction of the ferrous ion content. The initial permeability, however, is degraded as a result of annealing. It is suggested that stringent control of the oxygen partial pressure at an earlier stage of processing rather than post sintering annealing is necessary to raise the intrinsic electrical resistivity of the bulk materials by reducing the ferrous ion concentration without affecting the magnetic permeability detrimentally.