Study on the impact of Co-doping on the structural, spectroscopic, and magnetic properties of nano-crystalline MgFe2O4

Mg_1−xCo_xFe₂O₄ (x = 0.0–1.0) ferrites were synthesized through the sol–gel auto-combustion method to investigate their structural, vibrational, and magnetic properties. X-ray diffraction (XRD) pattern indicates the formation of a single-phase cubic spinel structure with space group Fd-3m. XRD revealed a non-linear variation in lattice parameter (8.3841 to 8.3650 Å) and crystallite size (12.27 ± 0.25 to 22.76 ± 0.29 nm) with increasing Co-concentration. FTIR spectra exhibited characteristic metal–oxygen vibrations in both tetrahedral and octahedral sites, supporting Co-substitution through redshift in absorption bands and intensity changes. Raman spectra showed enhanced vibrational ordering and sharper peaks with Co-doping, indicating improved cation distribution and stronger M–O bonding. XPS analysis suggested successful substitution of Mg²⁺ by Co²⁺/Co³⁺ ions as evidenced by the evolution of core-level spectra and binding energy shift. Magnetic measurements revealed a systematic increase in M_S (17.63 to 54.48 emu/g), H_C (20 to 1348 Oe), and magnetic anisotropy with Co-content, suggesting a transition from soft to hard magnetic behavior. The study shows Co-doping enhances structural and magnetic properties of MgFe₂O₄, suggesting potential application in magnetic data storage, permanent magnets, and spintronic devices.