Abstract
Ni-Zn ferrites with graded magnetic anisotropy for high frequency of megahertz order were prepared by the addition of CoO. When the CoO content increased, resonance frequency was expanded. However, initial permeability was decreased and anisotropy field was increased. Therefore we tried to prepare Ni-Zn ferrite with high initial permeability and high resonance frequency by the addition of graded CoO content. Troidal core samples were made to layer Ni-Zn ferrite with different CoO content. As the result, the sample which had large CoO content with inner layer, steep gradation and little Ni-Zn ferrite with outer layer showed excellent high frequency characteristics. The Ni-Zn ferrite added CoO with graded CoO content 0, 5, 0 wt.% had initial permeability of 80 for 20-60 MHz.
