The effect of Dy and Cu doping on structure and magnetic properties of LiZn ferrites

The microstructure and magnetic properties of Li0.3-y/2Zn0.4DyxCuyFe2.3-x-y/2O4 (x=0, 0.02, 0.04; y=0, 0.1) ferrites, synthesized via the sol-gel auto-combustion method, were systematically studied. It was found that for x<0.04, the samples maintain a pure cubic spinel structure. With increasing Dy content, porosity also increases; however, the codoping of Dy and Cu improves the overall material density. Due to the presence of nonmagnetic Dy and Cu ions, the saturation magnetization decreases as x and y increase. Additionally, the increase in grain size and decrease in magnetocrystalline anisotropy resulting from Dy and Cu doping lead to a significant increase in initial permeability, with a 48% enhancement observed when x=0.04 and y=0.1. Meanwhile, the Curie temperature was reduced by 9.6%. Although the cut-off frequency generally decreases with increasing x, it does not decrease with the introduction of Cu. Among the compositions, Li0.3Zn0.4Dy0.04Fe2.26O4 ferrite demonstrated the best thermal stability at high temperatures, indicating its potential for high-temperature and high-frequency applications.