Impact of Cr³⁺ substitution on Co_0.5Ni_0.25Mg_0.25Fe_2−xCr_xO₄ nano ferrites: structural and magnetic characteristics

Co_0.5Ni_0.25Mg_0.25Fe_2−xCr_xO₄ (x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.25) nano ferrites are studied with different Cr³⁺ concentrations in terms of their synthesis, magnetic properties, and crystal structure. The doped and undoped nanoferrites were prepared using sol-gel auto-combustion. Structural and magnetic research used XRD, FESEM, FTIR, and magnetic data. X-ray diffraction (XRD) patterns of the synthetic samples confirm the presence of a cubic symmetry, crystalline, single-phase spinel structure (Fd-3 m space group). The lattice constant is 8.452 to 8.384 A, and the typical crystallite size is 34 to 24 nm. According to morphology studies conducted with field emission scanning electron microscopy (FESEM), grain size increases with concentration. The FTIR spectra observed vibrational bands identify the tetrahedral and octahedral interstitial complexes in the spinel structure, hence validating the creation of the spinel phase. Additionally, the magnetic hysteresis loop data shows that the saturation magnetization decreases with increasing Cr³⁺ content.