Magnetic properties of exchange-coupled permanent magnets based on barium hexaferrite and cobalt ferrite nanocomposites

The strategy of blending hard and soft magnetic materials to synthesize nanocomposites offers new possibilities for magnetic materials. We focus on synthesizing and optimizing BaFe12O19-CoFe2O4 nanocomposites using a co-precipitation method to enhance the magnetic properties through exchange coupling. The synthesis conditions including pH, annealing temperature, and blending ratio were systematically investigated. The precursor synthesized at pH 13 produced uniform precipitates, and upon annealing at 1000 °C, barium hexaferrite (BH) and cobalt ferrite (CF) with hexagonal and spinel structure were each formed. The nanocomposite with a blending ratio of 0.75BH-0.25CF exhibited enhanced saturation magnetization and the highest remanent magnetization compared to the individual components. The crystal structure, morphology, and magnetic properties were characterized using X-ray diffraction, field-emission scanning electron microscopy, and vibrating sample magnetometry.