Preparation and characterization of core-shell structured α-Fe2O3/SiC spheres

Fe2O3/SiC composite microspheres with a core-shell structure were prepared by the carbothermal reduction reaction between poly(styrene sulfonic acid) iron salt and silica. X-ray diffraction, scanning electron microscope and magnetic properties measurement system were employed to characterize the morphology, structure and magnetic properties of the microspheres. From the results, the microspheres with a diameter of 150–400 μm have an α-Fe2O3 core and a SiC shell of tens of microns in thickness. The magnetism of the core-shell structured spheres at 104 Oe is much larger than that of pure α-Fe2O3 spheres prepared under the same conditions and the increment in magnetism is attributed to the introduction of iron silicides and SiC. By further chemical treatment, the α-Fe2O3/SiC microspheres can change into SiC hollow spheres, which have diameters similar to the magnetic spheres and mainly consist of irregular SiC particles. The formation mechanism of the composite and hollow spheres was also discussed.