High frequency magnetic properties and microstructure of NiZn/Co_2Z composite ferrite material

摘要

The NiZn(Ni_(0.4)Zn_(0.6)Fe_2O_4) spinel ferrite and Co_2Z(Ba_3Co_2Fe_(24)O_(41)) hexagonal ferrite composite materials with the various Co_2Z contents have been synthesized by the solid-state reaction method. The phases and microstructures of the sintered ceramics have been analyzed. The results show that Co_2Z grains exist as a secondary phase in composites and remarkably affect the grain size and the static and high-frequency magnetic properties. With the addition ratio of Co_2Z varying from 0 wt. % to 30 wt. %, the saturation magnetization only changes slightly and is closely related to the density of sintered composites. Meanwhile, the initial permeability decreases and the cut-off frequency expands from 7 MHz to 300 MHz. In addition, the product (μ_i - 1)f_r of composites is much larger than that of the pure NiZn spinel ferrite.