Optimizing the magnetic properties of nickel ferrite nanoparticles prepared by Co-precipitation method

Abstract In this study, soft magnetic nickel ferrite (NiFe 2 O 4 ) nanoparticles were successfully synthesized using a simple, low-cost, and eco-friendly co-precipitation method. The structural properties of the samples were enhanced through post-synthesis annealing at 400, 600, and 800 °C. X-ray diffraction (XRD) analysis revealed improved crystallinity and phase purity with increasing annealing temperature, as evidenced by the growth in crystallite size from 16.94 nm (as-prepared) to 42.57 nm at 800 °C and an increase in lattice constant from 8.294 to 8.344 Å. Field emission scanning electron microscopy (FESEM) images showed a significant increase in particle size from 20.04 nm to 146.60 nm with annealing. Energy-dispersive x-ray spectroscopy (EDS) confirmed enhanced compositional purity after heat treatment. Magnetically, the saturation magnetization (Ms) rose markedly from 0.567 to 80.851 emu g −1 , highlighting the impact of crystallite growth and improved magnetic ordering induced by thermal treatment.