Microstructure and magnetic properties of Ni–Zn ferrite ceramics with different Ni²⁺ contents

A series of Ni_xZn_1−xFe₂O₄ ( NiZn, x = 0.15, 0.25, 0.35, 0.45, 0.65, 0.7, 0.8, 0.85) ferrites were prepared via a solid-phase sintering method. The microstructure, phase, and gyromagnetic properties of the NiZn samples were studied in depth. It was found that the lattice constants, density, and hardness of the samples gradually decreased with increasing Ni²⁺ content. X-ray diffraction confirmed that all of the samples were in the spinel phase. Scanning electron microscopy indicated that the grain sizes were more uniformly distributed when x = 0.65. Raman analysis showed that the variation of Ni²⁺ content affected the occupancy distribution of ferrite ions. The results indicated that Zn²⁺ mainly occupied the A-site and that Ni²⁺ mainly occupied the B-site. The coercivity (H_c) of NiZn increased with increasing Ni²⁺ content. Meanwhile, the saturation magnetization (M_s) initially increased and then decreased. When x = 0.65, the total molecular magnetic moment started decreasing because of the decrease in the net A-site magnetic moment. The sample that had a composition of Ni_0.65Zn_0.35Fe₂O₄ had the highest M_s intensity with a value of 78.68 emu/g and a maximum value of 4πM_s = 4780 Gs.