Effect of Co₂O₃Addition on Stability of Permeability to an Impulse Magnetic Field in NiCuZn Ferrites

The NiCuZn ferrites doped with Bi2O3and Co2O3were prepared by the solid-state reaction method. Micrographs were obtained by SEM. The complex permeability spectra were measured by Agilent E4991A and 16454A. Variation of the permeability under a magnetic field impulse was measured by Agilent 4284A. Effect of the Co2O3content on the permeability spectra of the NiCuZn ferrite samples before and after exposing to an impulse magnetic field was discussed. The corresponding permeability spectra of the samples were decomposed into the domain wall motion component and the spin rotation component. The results show that the permeability at 1 MHz decreases and the resonance frequency increases with more Co2O3content, and Co2+have different effect on the two kinds of magnetic susceptibility components. Different variation was revealed for the domain wall motion component and the spin rotation component after exposing to an impulse magnetic field. The decline rate of susceptibility by domain wall motion is smaller than that of susceptibility by spin rotation.