Study On The Preparation And Application Of Iron Oxide Nano-materials

Controlled synthesis of nano-materials is extensively studied in recent years in materials science. The properties and usabilities of materials not only lie on constitute but relate to its microstructure. It was mainly focused the attention on preparation and application of iron oxides in this dissertation. The effects of controlling crystal type, morphology and mechanism were studied. In addition, a series of solid acid catalysts were prepared and applied to catalyze esterification reaction. The principal results of the dissertation are discussed as follows:Monodispersed α-Fe₂O₃ nano-particles were prepared by refluxing hydrothermal method. If using Fe(NO₃)₃ as staring materials , when initial pH=1, as the elongation of hydrothermal process, spindle-type α-Fe₂O₃ with porous structure would convert to monodispersed rhombhedral single crystal which average particle size was about 45 nm; when Fe(NO₃)₃ was neutralized by NH₃·H₂O to form Fe(OH)₃ gel, as the initial pH values increased, the formation of α-Fe₂O₃ was retarded, particle size decreased, but the structure of product became more perfect. Effects of surfactant on the formation rate of α-Fe₂O₃ using FeCl₃ solution as starting materials were studied. When added a small amount of CTAB into reaction system, the formation rate was significantly promoted; added DMF could also promoted the formation rate; but added SDS to reaction system, the formation rate was retarded.Monodispersed spindle-type α-Fe₂O₃ nano-particles were prepared by microwave hydrothermal gel-sol method using Fe(OH)₃ gel as precursor. The mechanism was Fe(â…¢) sol directly convert to α-Fe₂O₃ under microwave irradiation. It was studied that the effects of initial pH values on morphology of the product using Fe(NO₃)₃ as starting materials by microwave hydrothermal refluxing method. The convert rate of α-Fe₂O₃ was promoted through microwave hydrothermal method.α-Fe₂O₃ nano-particles were prepared by hydrothermal method using Fe(NO₃)₃ solution. The effects of initial pH values on the morphology were studied. When initial pH values were between 3～7, as pH values increased, particle sizes decreased and the spheric shape particles would convert to rhombhedral shape. As initial pH=9, the morphology of product was spheric but particle size became larger. Hydrothermal temperature and time, concentration of precursor had almost no influence on product morphology. Effect of doping metal ions on the preparation of α-Fe₂O₃ by hydrothermal method was also preliminary studied. It was found that the precursors pH=3, when doping Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺ ions, the product particles were rhombhedrol but the sizes increased; when doping...