Enhancement of magnetic and dielectric properties of low temperature sintered NiCuZn ferrite by Bi₂O₃–CuO additives

Abstract

With a series of 1.0 wt%Bi2O3–x wt% CuO (x = 0.0, 0.2, 0.4, 0.6, and 0.8) serving as sintering additives, Ni0.23Cu0.32Zn0.45Fe2O4 ferrites are successfully synthesized at a low temperature (900 °C) by using the solid state reaction method. The effects of the additives on the phase formation, magnetic and dielectric properties as well as the structural and gyromagnetic properties are investigated. The x-ray diffraction (XRD) results indicate that the added Bi2O3–CuO can lower the synthesis temperature significantly without the appearing of the second phase. The scanning electron microscope (SEM) images confirm that Bi2O3 is an important factor that determines the sintering behaviors, while CuO affects the grain size and densification. With CuO content x = 0.4 or 0.6, the sample shows high saturation magnetization, low coercivity, high real part of magnetic permeability, dielectric permittivity, and small ferromagnetic resonance linewidth (ΔH). The NiCuZn ferrites are a promising new generation of high-performance microwave devices, such as phase shifters and isolators.

Effect of Bi2O3–CuO Flux on the Microstructure, Soft Magnetic Properties, and Gyromagnetic Properties of NiCuZn Ferrites for LTCC Devices

“…Thus, the reduction in ΔH was due to an enhancement of 4πMs and an increase in porosity. The results imply that the reduction in small grains can enhance the uniformity of ferrite grains and lower ΔH via appropriate CuO substitution [19,20]. The ΔH is a macroscopic physical quantity that reflects the damping experienced by the magnetization during its precession.…”