Effect of Eu-doping on high-frequency electromagnetic performance of Ni0.4Zn0.4-xCu0.2EuxFe2O4+0.5x ferrite toroid core

To meet the demands of modern high-frequency electronic applications, the Eu-doped Ni0.4Zn0.4- xCu0.2EuxFe2O4+0.5x (x = 0, 0.02, 0.04, and 0.06) toroid cores were fabricated via co-precipitation combined with solid-state sintering method in this work. The phase compositions, chemical state, and the hysteresis loops of the ferrite powders were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and vibrating sample magnetometer, respectively. The micromorphology, complex permeability, inductance versus the direct current bias as well as power loss density of the toroid cores were measured by scanning electron microscopy, impedance analyzer, and AC magnetic properties measuring system, respectively. The results demonstrated that appropriate amounts of Eu could replace Zn2+ to form a ferrite solid solution, which promotes grain growth and reduces porosity, thereby enhancing the initial permeability and reducing the power loss density. The optimal performance of toroid core, sintered at 950 degrees C with x = 0.02, exhibits the lowest power loss density under 1 MHz both at 5 mT and 10 mT excitation, which is reduced by 7.74 % and 12.19 % compared with the undoped core, respectively. This work provides a high-performance material design for high-frequency power electronic applications.