Phase-morphology evolution and magnetic properties during the annealing process of SrFe12O19 ferrites obtained using cubic α-Fe2O3 particles

Hard magnetic magnetoplumbite-type SrFe₁₂O₁₉ ferrite is widely used due to its fine chemical stability, high cost-effectiveness and good magnetic properties. Figuring out the phase-morphology evolution and magnetic properties during annealing at high temperatures is essential for establishing structure–property relationships for SrFe₁₂O₁₉ ferrites. In this study, a traditional ceramic method was used to prepare SrFe₁₂O₁₉ ferrites using cubic α-Fe₂O₃ nanoparticles obtained via a hydrothermal method as Fe sources, and the phase-morphology evolution and magnetic properties at different annealing stages were studied. With the increase of annealing temperature, the morphology changes of cubic α-Fe₂O₃ accompanied with the phase evolution were found to critically determine the magnetic properties. A morphology model was built to elaborate the relationship between phase-morphology and magnetic properties for SrFe₁₂O₁₉ ferrites. It was found that the specimen annealed at 1100℃ exhibited the best comprehensive magnetic properties in this study, whose saturation magnetization and coercivity are 68.89 emu/g and 256.34 kA/m, respectively.