Analyses on the dispersion spectra of permeability and permittivity for NiZn spinel ferrites doped with SiO2

The permeability spectra of NiZn spinel ferrites with different amounts of SiO2 (0,0.3,0.5wt%) aggregated at the grain boundaries have been resolved into two contribution components: domain wall resonance and spin rotation relaxation. The fitting results of permeability dispersion show that the spin rotation relaxation mechanism makes major contributions to the dispersion. With increasing the contents of SiO2, the fitting results of permittivity dispersion spectra show a wider distribution of relaxation time and a longer relaxation time.