Comparison of Magnetic Properties of SrFe12O19/Co0.8Fe2.2O4 Composite Materials Prepared by Sol-gel and Hydrothermal Processes

Abstract

The preparation process of composite magnetic materials may affect the phase composition and microstructure, thereby affecting their magnetic properties. However, a systematic comparison of the properties and the correlation between process parameters and magnetic properties has not been sufficiently elucidated. Herein, SrFe12O19/Co0.8Fe2.2O4 composite magnetic materials with a mass ratio of 5:5 were prepared by both the sol-gel and hydrothermal methods using SrFe12O19 as the hard magnetic phase and Co0.8Fe2.2O4 as the soft magnetic phase. The influences of heat treatment temperature on the phase formation, morphology, and magnetic properties were studied by various analytical techniques, and the results were compared. The analyses indicate the hydrothermal method is capable of producing samples with pure phase, particle size of approximately 25 nm, and excellent dispersion at temperatures from 120 to 160°C. By comparison, the sol-gel method requires annealing at 1200°C to eliminate impurities and yield micron-sized samples with obvious agglomeration. In terms of magnetic properties, the sol-gel method induces higher coercivity and saturation magnetization in samples, with the coercivity reaching 2648 Oe after annealing at 1000°C, while the hydrothermal method ensures better control at low temperatures for finer particle size production. In summary, the sol-gel method suits scenarios pursuing high magnetic properties, while the hydrothermal method suits scenarios pursuing low temperature and small particle size requirements. The provided pros and cons of each preparation method would have great potential for process optimization and performance regulation of composite magnetic materials.