حسین نیک منش

We report that a high coercivity of CoCr ferrite was achieved via hydrothermal synthesis at low annealing temperatures. In particular, CoCr0.6Fe1.4O4 exhibits a coercivity of 6.841 kOe at an annealing temperature of 150 °C. CoCr0.6Fe1.4O4 nanoparticles were synthesized using a hydrothermal method followed by annealing at 150 °C, 175 °C, 200 °C, and 225 °C to tune their structural and magnetic properties. Vibrating sample magnetometer (VSM) measurements showed that saturation magnetization (Ms=6.43-22.76 emu/g) and remanence (Mr=4.18-15.69 emu/g) increased systematically with grain growth, while the maximum coercivity was obtained at 150 °C due to defect and strain. First-order reversal curve (FORC) analysis revealed multiple interaction mechanisms among nanoparticles, with both positive and negative interaction fields. Also, it shows the coexistence of magnetically soft and hard domains. The Reversal anisotropy parameter, derived from δk/δH as a function of -Hr, exhibited distinct peaks corresponding to hard and soft magnetic phases, confirming anisotropy evolution and consistent trends with hysteresis-derived anisotropy constants. X-ray diffraction (XRD) patterns confirmed a single-phase spinel structure while photoluminescence (PL) spectra results reflecting reduced defect density and recombination. The low PL intensity of the 150 °C sample implies suppressed electron-hole recombination and enhanced photocatalytic efficiency. These results demonstrate that CoCr0.6Fe1.4O4 nanoparticles, with their tunable magnetic and optical responses, are suitable for multifunctional applications such as magnetically separable photocatalysts, magnetic data storage.