The Research Of The Fe₂O₃Hollow Spheres Prepared By The Modified Carbon Template Method

Since the21st century, the synthesis of various functional materials has been made a great of achievements, especially the nanoscale materials. The hollow structure in the nanoscale material has become an important way to realize the function of the materials. Fe2O3, as one of the normal metal compound, is used as the raw materials of magnetic ferrites. The preparation of the hollow Fe2O3spheres extends the application.In this article, the ammonia was added in the hydrothermal process of produce carbon spheres templates. The addition of the ammonia can promote the growth of the spheres efficiently. Because the NH4+reacts with the decomposition product of the glucose and the intermediate products form, which accelerate the carbonization reaction and form the3D network structure. At the same time, the NH4+is absorbed on the surface of the sphere, which provides the same charge and prevents the reunion and crosslinking between the microspheres. This produces the good dispersivity.The spheres were used as the template to synthesis the Fe2O3 hollow sphere. Two methods containing the layer by layer method and the chemical deposition method were used in this thesis to produce the Fe2O3and ZnFe2O4. The results were characterized by XRD and SEM. The results show that the process of the chemical deposition method was more complex than the layer by layer method. However the former process can well be controlled to adjust the thickness of the spherical shell and the diameter of the hollow spheres. In addition, the diameter of the hollow spheres was smaller than the template and has a wrinkled surface.The process of one step way to produce Fe2O3was improved in this article. The Fe (NO3)3·9H20, glucose and ammonia were added in the kettle together. After the hydrothermal reaction and burned, the hollow spheres were achieved. With the help of the XRD and SEM analysis, the mechanism was discussed. The results show that the morphology of the hollow spheres was influenced by the initial contents of raw materials and the pH values. After the addition of the ammonia, the absorption action of the Fe2O3precursor on the carbon balls is changed from the electrostatic interaction to the chemical interaction. It decreases the reaction time and improves the efficiency of the preparation. During this course, the stable pH value with the range of3-7can benefit making the precursor cover the sphere better and producing homogeneous hollow spheres.