Morphology Controlled Fabrication And Property Research Of Iron Oxide Nanomaterials

Recently considerable research interest is focused on nanostructured magnetic materials, with the expectation to control their composition, microstructure and morphology due to their wide potential uses. Various iron oxide based materials are still the most important and common magnetic materials. Hence, developing simple process for the preparation of various iron oxides, especially aqueous solution strategy, is of great interest for the simple and low cost synthesis of magnetic materials for their further large-scale applications.In the present work, through exploring the inherent chemical properties of the synthetic systems, several aqueous solution processes are developed for morphology controlled fabrication of iron oxides via substrate selection, nucleation and growth control and changing reaction environment, towards developing new strategies for simple and low cost synthesis of magnetic materials.1. High quality Fe3O4 octahedral particles of ~500nm were successfully synthesized from iron powders by simple hydrothermal treatment with 10 M NaOH at 180°C.2. Uniform hollow hematite spheres were successfully synthesized by a simple polyoxometalate-assisted hydrolysis process of Fe3+ solution under hydrothermal condition. The hollow spheres with diameters of 600-700 nm show a high surface area and weak ferromagnetic behavior due to their porous structure. Formation of the hollow hematite spheres may be attributed to a polyoxometalte-assisted forced hydrolysis and dissolution process.3. Uniform porous p-FeOOH nanorods of 10-20 nm have been sucessfully fabricated by further exploring the polyoxometalate-assisted hydrolysis process of Fe3+ solution. Porous hematite nanorods could be obtained from direct calcination of the P-FeOOH nanorods.4. Uniform ferrite MFe2O4 (M=Mg, Co, Ni, Zn) hollow spheres are successfully prepared by hydrothermal treatment of a mixed solution of glucose, Fe3+ and M2+ and a following calcination process. Formation of the hollow spheres is ascribed to the in situ formed carbon core as template. The shell thickness, crystallinity and consequently magnetic property of the ferrite hollow spheres could be tuned by varying the synthetic parameters.