Impact of nickel doping on the optical, magnetic and electrical properties of CMFC ferrite

The multifunctional properties of spinel ferrites can be effectively tailored through Ni substitution, particularly in systems where cation redistribution and electron hopping mechanisms govern the structural, optical, electrical, and magnetic responses. In this work, Cu₀.₇Mg₀.₃₋ₓNiₓFe₁.₇Cr₀.₃O₄ CMFC ferrites (0.05 ≤ x ≤ 0.30) were synthesized and systematically investigated using XRD, SEM, optical and transport properties analysis. Ni incorporation promoted improved lattice ordering and cation redistribution within the spinel structure, leading to modifications in electronic polarizability and charge transport pathways. These changes were reflected in a systematic widening of the optical band gap from 3.2 to 3.7 eV, accompanied by a reduction in the refractive index. Magnetic measurements confirmed the retention of soft ferromagnetic behaviour, although the saturation magnetization gradually decreased from 20.33 to 18.54 emu g⁻¹ due to variations in cation occupancy and superexchange interactions. The saturation magnetization slightly reduced while preserving soft magnetic behavior with low coercivity (44-57 G). The results of the magnetic properties indicated that, the magnetic response for specific applications such as High-Frequency Transformer Cores, Electromagnetic Interference (EMI) Suppression and Magnetic Recording Heads. Dielectric analysis performed over the frequency range 10⁻¹-1 M Hz at 30 °C revealed pronounced low-frequency dispersion associated with Maxwell-Wagner interfacial polarization at low frequency. The combined structural, optical, electrical, and magnetic characteristics indicate that Ni-substituted Cu-Mg ferrites are promising materials for MHz-frequency electronic devices, including high-frequency transformer cores, electromagnetic interference suppression, and magnetic recording components.