Electrical and magnetic properties of low-temperature sintered xBa0.6Sr0.4TiO3 + (1 − x)Ni0.2Cu0.2Zn0.62O(Fe2O3)0.98 composite ceramics

For the purpose of multilayer chip electromagnetic interference (EMI) filters, a series of xBa0.6Sr0.4TiO3 (BST) + (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 composite ceramics can be sintered to a density >95% of theoretical density at 925 °C. The effects of composition x on the sintering behaviors, phase compositions and electromagnetic properties of BST + NiCuZn ferrite composite materials were investigated. X-ray diffraction (XRD) results showed that the composites were composed of BST and NiCuZn phases. The ions’ diffusion was found to take place between NiCuZn ferrite and BST, which affected the electrical properties of the ceramics. With an increase of BST content x, the dielectric constant of the composites increases and the permeability decreases. For the specimens with 40 wt.% Ba0.6Sr0.4TiO3–60 wt.% Ni0.2Cu0.2Zn0.62O(Fe2O3)0.98, the good dielectric (ɛr = 48, tan δ|ɛ = 0.01) and magnetic properties (μ = 20.8, tan δ|10 MHz = 0.03) have been obtained at 950 °C. Meanwhile, it exhibited excellent frequency stability which was up to fr = 100 MHz.