Synthesis of core-shell α-Fe2O3 hollow micro-spheres by a simple two-step process

Core-shell Fe2O3 hollow micro-spheres have been fabricated by a simple two-step method. Firstly, compound of carbon and iron hydrate were synthesized by hydrothermal process. The obtained products were characterized by X-ray diffraction (XRD), which exhibit the diffraction peaks of orthorhombic phase of iron oxide hydroxide. Energy dispersive X-ray spectroscopy (EDS) measurement indicates the existence of carbon. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results show flake-based urchin-like architecture. Secondly, core-shell hollow micro-spheres were obtained by subsequent annealing process. XRD pattern of the final sample is well in agreement with the standard pattern of the hexagonal rhomb-centered alpha-Fe2O3. FE-SEM and TEM images reveal that those hollow spheres are of core-shell architecture with holes on the surfaces. Magnetic hysteresis measurement carried out on vibrant sample magnetometer (VSM) shows weak ferromagnetic property at room temperature. On the basis of the obtained experimental results, the possible formation mechanism was discussed. (C) 2009 Elsevier B.V. All rights reserved.