Magnetic properties and microwave absorption of Ni₀.₇Zn_0.3A_0.05Fe₁.₉₅O₄ (A = La, Ce, and Nd) powders within the range of 2–18 GHz

Ni_0.7Zn_0.3A_0.05Fe_1.95O₄ (A = La, Ce, and Nd) powders were obtained by the sol-gel combustion technique. The phase composition, microstructure, and electromagnetic properties of La³⁺, Ce³⁺, and Nd³⁺ substituted Ni_0.7Zn_0.3Fe₂O₄ were investigated. Compared with the Ni_0.7Zn_0.3Fe₂O₄ ferrite, the saturation magnetization of substituted Ni_0.7Zn_0.3Fe₂O₄ powders decreases due to the reduction of the super-exchange interaction by the substitution of La³⁺, Ce³⁺, and Nd³⁺at the Fe site. Furthermore, the enhanced dielectric constant of the substituted Ni_0.7Zn_0.3Fe₂O₄ ferrites prompts to the formation of good impedance matching and thereby improving the microwave absorption performance. The best reflection loss of Ni_0.7Zn_0.3Ce_0.05Fe_1.95O₄ ferrite is −17.5 dB at 13.8 GHz, and the corresponding absorption bandwidth (RL ≤ 5 dB) can be achieved 10.9 GHz. These results suggested that the Ni_0.7Zn_0.3Ce_0.05Fe_1.95O₄ ferrite is a potential composite for electromagnetic applications, particularly for broadband microwave absorption.