Preparation And Magnetic Properties Of ?-Fe₂O₃ Nanoparticles

With the rapid development of science,there are more and more researches on nanomaterials.Among them,nano-iron oxides have attracted more and more attention from the scientific community because of their considerable application prospects.Due to the superparamagnetic and high saturation magnetization values of some iron oxide phases and the non-toxicity,biocompatibility and other biochemical characteristics,nano iron oxide can be used for medical diagnosis,ferrofluid and other medical applications.And it plays an important role in some studies such as magnetized quantum tunneling.Compared with other nano-oxides,?-phase ferric oxide has been widely used in magnetic recording media,information storage,permanent magnets and other practical applications due to its excellent coercive force,electromagnetic coupling,and ferromagnetic resonance.Therefore,there have been more and more reports on the research of?-Fe₂O₃ in recent years.Because the preparation of?-Fe₂O₃ is very sensitive to experimental conditions.It is stable only in certain sizes and can be easily converted to?-Fe₂O₃.Therefore,the preparation of?-Fe₂O₃ has always been the focus of research.In this thesis,?-Fe₂O₃nanoparticles were synthesized using the reverse micelle-sol-gel method,the ball milling method and the dipping method.1.?-Fe₂O₃ nanoparticles were synthesized by reverse micelle-sol-gel method.The reverse micelle-sol-gel method,the reaction mechanism for preparing?-Fe₂O₃,the structure,morphology and magnetic properties of?-Fe₂O₃ are introduced.From the ratio of the amount of water to cetyltrimethylammonium bromide,the content of ferric nitrate nonahydrate,and the content of barium nitrate,their effects on the morphology of?-Fe₂O₃ were discussed.Transmission electron microscopy showed that the larger the ratio of the amount of water to cetyltrimethylammonium bromide,the larger the particle size of?-Fe₂O₃,the greater the content of iron nitrate nonahydrate,and the larger the particle size of?-Fe₂O₃.The larger the content of barium nitrate,the morphology of?-Fe₂O₃ changes from ellipse to rod.2.?-Fe₂O₃ nanoparticles were prepared by ball milling.?-Fe₂O₃ nanoparticles were prepared by ball milling ferric nitrate nonahydrate and hydrophilic fumed silica and subsequent annealing.The effect of the content of ferric nitrate nonahydrate on the sample product was discussed.The particle size of?-Fe₂O₃ was compared by transmission electron microscopy.The magnetic properties of?-Fe₂O₃ nanoparticles were compared by physical property measurement system.This method is a new synthesis method for synthesizing?-Fe₂O₃ nanoparticles,and has the advantages of simple operation,no pollution,and mass production.3.?-Fe₂O₃ nanoparticles were prepared by dipping method.Iron ions were impregnated into the pores of silica xerogel by dipping technique,and?-Fe₂O₃ is prepared by annealing.The structure and magnetic properties of the samples were analyzed by XRD and PPMS.The particle size of the sample was analyzed by TEM.Discuss the effect of iron nitrate nonahydrate content on?-Fe₂O₃.The?-Fe₂O₃nanoparticles are prepared by the impregnation method.The raw materials are cheap,non-toxic and easy to obtain.At the same time,the experimental process is simple to operate and does not pollute the air.The prepared sample has small particles,narrow size distribution and even distribution in SiO₂.This thesis focuses on experimental preparation,supplemented by characterization.The process of synthesizing?-Fe₂O₃ nanoparticles by three methods is discussed.And a new preparation method of ball milling method is proposed.It is a basic task and an inevitable choice for modern science and industrial development to prepare nanomaterials in large quantities by simple and easy-to-use experimental methods.