Crystal structure-physical properties correlation in Ni–Cu–Zn spinel ferrite

Ni/Zn co-substituted copper ferrites (Cu_1−3xNi_xZn_2xFe₂O₄) with a step interval of 0.01 and 0.0 ≤ x ≤ 0.06 were synthesized using the sol–gel method. The microstructural, elastic, and magnetic properties of the samples were investigated using Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometry. Structural results revealed a phase transition from tetragonal (I41/amd space group) to cubic ( \(Fd\overline{3 }M\) $Fd\overline{3}M$ space group) with increasing Ni/Zn co-substitution, which was corroborated by Raman and FTIR spectroscopies. The elastic properties of the samples were found to increase with Ni/Zn co-substitution. A hard-to-soft magnetic phase transition was observed with increasing Ni/Zn co-substitution, characterized by a sharp decrease in the coercive field from 745.61 to 41.21 Oe and an increase in saturation magnetization from 22.51 to 50.65 emu/g. Overall, this study provides valuable insights into the correlations between structural phase transitions and physical properties in Ni/Zn co-substituted copper ferrites, opening up possibilities for tailoring these materials for data storage, spintronics, magnetic refrigeration, and biomedicine applications.