Tailoring Magnetic Properties and Power Loss in Low-Temperature Sintered NiCuZn Ferrites with BMLS-CaTiO3/BaTiO3 Composite Additives

In this study, NiCuZn ferrites were prepared via a solid-phase method at a reduced sintering temperature of 925 °C. A composite additive system was developed by incorporating Bi2O3-MgO-Li2CO3-SiO2 (BMLS) glass with varying amounts of either CaTiO3 or BaTiO3, aiming to modify the magnetic performance and power loss behavior of the ferrites. The effects of BMLS-CaTiO3 (Group A) and BMLS–BaTiO3 (Group B) on the crystalline structure, density, electrical resistivity, microstructure, magnetic properties, as well as power loss were systematically investigated, and the underlying mechanisms were thoroughly discussed. Magnetic characterization revealed that the addition of BMLS-CaTiO3/BaTiO3 decreased the saturation magnetization (Ms) and permeability, primarily due to the magnetic dilution, as well as a reduction in density and grain size. However, the intrinsic coercivity increased, which can be attributed to the pinning of magnetic domain walls by the glass phase located at the grain boundaries and the reduction in crystallite size. The resistivity increased first and then decreased with the increasing content of CaTiO3/BaTiO3. When x = 0.1, samples in Group A and Group B reached the maximum values of 473.16 MΩ·m and 453.12 MΩ·m, respectively. Nonetheless, with an additive content of 0.05 wt%, samples in Group A and Group B still exhibited comparatively high Ms values of 53.93 emu/g and 54.65 emu/g, as well as high permeability values of 636.95 and 651.55, respectively. Meanwhile, power loss measurements indicated a notable reduction in total power loss across various frequencies and magnetic induction levels for both groups, with losses decreasing by more than 35%. Further analysis attributed these changes to enhanced grain uniformity, improved densification, and increased resistivity resulting from the incorporation of BMLS-CaTiO3/BaTiO3.