Facile preparation and characterization of glass/α-Fe2O3 core/shell composite hollow spheres with the shell layer assembled by disk-like petals

Novel core/shell composite hollow spheres were successfully synthesized by a facile hydrothermal process. The composite spheres consisted of a hollow glass core and an iron oxide (α-Fe2O3) shell assembled by disk-like petals. By properly tuning the process conditions and the component of the reaction solution, a series of composite spheres with gradient in morphologies of the shell layer could be prepared. The products present wide open M–H loops (hysteresis loops) related to the special shell morphologies. With the building units of the α-Fe2O3 shells varied from spherical nanoparticles to disk-like nanopetals, the coercivity increased from 414.93Oe to 2201.90Oe. Based on a series of contrast experiments, the probable formation mechanism of the products was proposed.