Effects of Bi2O3–CuO additives on microstructure and microwave properties of low-temperature-sintered NiCuZn ferrite ceramics

Abstract

In this study, (Ni0.2Cu0.2Zn0.6O)1.03(Fe2O3)0.97 ferrite ceramics with low microwave loss were synthesized through low-temperature sintering and doped with low eutectic mixture Bi2O3–CuO. Additionally, the influence of Bi2O3–CuO doping amount on phase composition, microstructure, and microwave performance of NiCuZn ferrite ceramics was systematically explored. It was found that all samples exhibited pure spinel phase. Moreover, scanning electron microscopy analysis revealed that appropriate doping amount of the Bi2O3–CuO mixture promoted grain growth and densification, leading to dense dual microstructure in NiCuZn ferrite ceramics. Notably, this microstructure significantly enhanced microwave properties of the material. For Bi2O3–CuO doping amount of 0.5 wt % and at sintering temperature of 910 °C, the NiCuZn ferrite ceramics exhibited low ferromagnetic resonance linewidth (ΔH ≈ 90 Oe), minimal dielectric loss (tanδε ≈ 2.73 × 10−4) at 9.3 GHz, and high saturation magnetization (4πMs ≈ 3644 Gauss). These results highlight the potential of Bi2O3–CuO as promising sintering aid, which could support the application of NiCuZn ferrite ceramics to microwave devices.