Time Decrease of Magnetic Permeability in Some Mixed Ferrites

抄録

The time decrease of the magnetic permeability after demagnetization, or disaccomodation, was measured for Mn-Zn, Ni-Zn, Cu-Zn and Mg-Zn ceramic ferrites. Considerable disaccomodation was observed with samples containing Fe₂O₃ over the stoichiometric composition. In the case of Mg-Zn ferrites, the disaccomodation is remarkable on both sides of the stoichiometric composition, where it is fairly small. For the specimens sintered in air, the disaccomodation is larger for higher electrical-conductive specimens, while such a correlation to the conductivity disappeared after the specimens were annealed in the nitrogen atmosphere. A single crystal of Ni-Zn ferrite, which is supposed to contain a very small amount of vacancies, also shows a very small disaccomodation. The activation energy determined from the disaccomodation measurements is about 0.5–0.8 eV for Mg-Zn ferrites. It is suggested that the displacement of either vacancies or interstitial ions may possibly be a main origin of the phenomenon.