Permeability Dispersion and Magnetic Loss of ${\rm Fe}/{\rm Ni}_{\rm x}{\rm Zn}_{1-{\rm x}}{\rm Fe}_{2}{\rm O}_{4}$ Soft Magnetic Composites

${\rm Fe}/{\rm Ni}_{\rm x}{\rm Zn}_{1-{\rm x}}{\rm Fe}_{2}{\rm O}_{4}$
(
${\rm x}=0.1$
, 0.3, 0.5, 0.7, 0.9) soft magnetic composites were prepared by the chemical co-precipitation method. The effect of Ni content on the magnetic properties was discussed. The results of SEM, EDS and X-ray diffraction analysis indicate that an uniform and dense Ni-Zn ferrite was coated on the surface of bared Fe. The maximum of saturation magnetization of soft magnetic composites was obtained at
${\rm x}=0.7$
, however its magnetic loss is largest at 10–100 kHz. Analyzes of permeability spectra of the soft magnetic composites show that the contribution of spin rotation to the spectra becomes comparable with that of domain wall movement due to the magnetic insulating ferrite coating, which helps improve the working frequency of the soft magnetic composites drastically.