Low-temperature sintering LiZnTiMn ferrite ceramics: synthesis, microstructure, and enhanced ferromagnetic properties with CuO–V₂O₅ additive

In this study, a new method was developed for the coexistence of different grain sizes and the densification of low-temperature sintered Li_0.42Zn_0.27Ti_0.11Mn_0.1Fe_2.1O₄ (LiZnTiMn) ferrite ceramics. Excellent gyromagnetic performance was realized for the LiZnTiMn ferrite ceramics by controlling the amount of CuO–V₂O₅ sintering additive. In particular, the appropriate amount of CuO–V₂O₅ sintering additive effectively restrained the abnormal grain growth and enhanced the densification of low-temperature sintering ferrite ceramics. In addition, scanning electron microscopy images indicated different grain sizes (large grains of ~ 10 µm and small grains of ~ 2 µm) because of the existence of V₂O₅–CuV₂O₆ eutectic compounds. The addition of the optimum amount of CuO–V₂O₅ resulted in LiZnTiMn ferrite ceramics with high saturation magnetization and low coercivity (ferromagnetic resonance line width was narrow). For the sample with 0.5 wt% CuO–V₂O₅ additive, a pure spinel phase was synthesized at a low firing temperature (~ 900 °C). In addition, the sample possessed significantly enhanced microwave ferromagnetic properties: M_s = 78.56 emu/g, B_r/B_s = 0.85, H_c = 167 A/m, and △H = 167 Oe, making it useful as a new type of gyromagnetic material. These newly developed ceramic materials could be suitable candidates for microwave low-temperature co-fired ceramic gyromagnetic devices.