Pressure Dependence of Disaccommodation in Ni-Zn Ferrite with Co Impurity

The initial permeability decay, which is caused by disaccommodation in a polycrystalline Ni-Zn ferrite sample, was measured in a ¿60 ~ ¿40°C range under hydrostatic pressure of 1 bar to 2.5 kbar. The results were analyzed using a Richter-type relaxation hypothesis. The temperature dependence study of the upper limit T2 of the relaxation time spectrum gave the activation energy of 0.58 eV. The activation volume determined from the pressure dependence of T2 was found to be dependent on temperature and its size had an order of magnitude of 1 cm³/mol. These results are compatible with the view that the observed disaccommodation is caused by ionic diffusion, in spite of the widely accepted view that it is due to electron diffusion in this material. From these results, the ionic diffusion model seems to be more favorable than the widely accepted electron diffusion model.