Guo-Guang Yao

ELECTRICAL AND MAGNETIC PROPERTIES OF LOW-TEMPERATURE SINTERED xTiO2+(1-x)Ni0.2Cu0.2Zn0.62O(Fe2O3)0.98 CERAMICS

For the purpose of multi-layer chip electromagnetic interference (EMI) filters, a series of xTiO2 + (1 - x)Ni0.2Cu0.2Zn0.62O(Fe2O3)0.98 (NiCuZn ferrite) (0 ≤ x ≤ 60 wt.%) composite ceramics were primarily prepared by a solid-state reaction method. With addition of 3 wt.% Bi2O3, all the ceramics can be sintered at 900°C. The effects of composition x on the sintering behaviors, phase compositions and electromagnetic properties of TiO2+NiCuZn ferrite ceramics were investigated. The X-ray diffraction (XRD) results showed that the ceramics were composed of NiCuZn, Fe3Ti3O10 and TiO2 phases. Scanning electron micrographs showed that 10 wt.% TiO2 to 90 wt.% Ni0.2Cu0.2Zn0.62O(Fe2O3)0.98 ceramics had small grain size and high density. With an increase of TiO2 content x, the value of er decreased and the component with 10 wt.% TiO2 had maximum relative dielectric constant. The permeability and the saturation magnetization decreased gradually with increasing TiO2 content, and the permeability curve exhibited excellent stability of frequency. The composite materials with 10 wt.% TiO2 showed typical magnetic hysteresis of the magnetic materials. For the specimens with 10 wt.% TiO2 to 90 wt.% Ni0.2Cu0.2Zn0.62O(Fe2O3)0.98, the good dielectric (er = 50) and magnetic properties (μ = 30, tanδ|10 MHz = 0.13) have been obtained at 900°C.