High Saturated-Magnetization-Realization Induced by Zinc Substitution in Cobalt Ferrite Nanoparticles Synthesized via Sol-Gel Method

Cobalt ferrite (CoFe2O4) is a promising spinel ferrite material due to its high chemical stability, moderate saturation magnetization, and significant coercivity, making it attractive for various technological applications such as magnetic data storage, sensors, and photocatalysis. Tailoring its properties via cationic substitution enables precise tuning of both structural and magnetic characteristics. In this study, zinc-substituted cobalt ferrite nanoparticles with Zn2+ concentrations of x = 0, 0.2 and 0.4 were synthesized via the sol-gel method and thermally annealed at 450 °C for 6 h. X-ray diffraction (XRD) patterns confirmed a single-phase face-centered cubic spinel structure (space group Fd-3m), corroborated by Rietveld refinement. FTIR spectra revealed characteristic vibrational bands at tetrahedral (v1) and octahedral (v2) sites, confirming spinel formation. Magnetic measurements showed a significant reduction in coercivity from 1,130 Oe (x = 0) to 247 Oe (x = 0.4), attributed to a domain transition from single- to multi-domain structure. Meanwhile, saturation magnetization increased from 75.77 to 104.74 emu/g, linked to the redistribution of non-magnetic Zn2+ ions to tetrahedral sites, replacing magnetic Co2+, and the migration of Fe3+ to octahedral positions. Additionally, the emergence of spin reverse-orientation of Fe3+ at tetrahedral sublattice contributed to the enhancement in magnetization. These interpretations were further supported by magnetic structure simulations using the BasIreps program, confirming the presence of spin-down ordering in trivalent cation of tetrahedral site. This study provides insights into Zn’s role in modulating the magneto-structural behavior of cobalt ferrite for advanced magnetic materials. HIGHLIGHTS Zn substitution effectively tailors structural and magnetic properties. Magnetization (Ms) increases while coercivity (Hc) decreases with higher Zn content. BasIreps confirms spin reverse-orientation correlated with rising saturation magnetization. GRAPHICAL ABSTRACT