Preparation,Structure And Magnetic Properties Of Carbon-encapsulated Magnetite,Martensite,and Iron Nanoparticles By High Energy Ball Milling Method

Compared with bulk materials,magnetic nanomaterials show more special physical and chemical properties.Fe₃O₄,martensite,and iron are kinds of important magnetic materials and have many excellent properties.The nanomaterials show strong surface activity and inherent magnetic when the nanomaterials become smaller.It is easy to agglomerate to lose the special properties,thereby affecting the performance in the fields of magnetism,electricity and optics.Carbon-encapsulated magnetic nanoparticles exhibit good properties due to the uniformly carbon encapsulation.The composite not only have the unique properties of each component material,but also effectively exert the synergistic properties between carbon and magnetic materials.Carbon-encapsulated magnetic nanoparticles have encouraging wide-range of potential applications in the fields of magnetic recording media,targeted drug delivery,magnetic fluids,and catalysis,and have great potential in Energy,Biosensors.Therefore,it is of great significance to find a more efficient and convenient preparation method,which can form coating on the surface to protect the properties of the magnetic nanoparticles,and can effectively control the crystal structure,morphology,and size.There are many methods to successfully synthesize carbon-encapsulated nanoparticles,such as hydrothermal,pyrolysis,chemical vapor deposition,arc discharge and explosion.Although these methods have been extensively studied,there are still some disadvantages.Commonly,the encapsulation of carbon on the magnetic nanoparticles is associated with use of?i?expensive experimental equipments and complex procedures,?ii?high temperature and high pressure conditions,or?iii?toxic precursors.The high-energy ball milling method mainly used in this paper is an efficient and simple preparation method.It mainly uses continuous collisions and extrusions in the grinding tank between the grinding balls,so that the reaction raw materials are fully mixed and deformed and broken after continuous impact.The huge mechanical energy causes intense chemical reactions and phase changes in the system,and carbon-coated magnetic nanoparticles with small size distribution and uniform dispersion can be prepared in large quantities in a short time.And this process is simple and efficient,environmentally friendly,and suitable for industrial production.The main experimental content is as follows:1.Using iron nitrate as the iron source,dopamine and glucose as the carbon source and reducing agent,high-energy ball milling was used to prepare carbon-encapsulated magnetic nanoparticles with a uniform shape and a diameter of about 10 nm.The results show that dopamine and glucose can not only be used as carbon source materials to form carbon coating,but also have good reducibility to Fe³⁺ions.The main advantages of the method are simple process,low cost,abundant output and suitable for industrial production,which can make up for the shortcomings of the existing experimental methods.The main advantages of the method are simple process,low cost,abundant output and suitable for industrial production.2.By changing the initial amount of carbon source material,carbon-encapsulated Fe₃O₄,martensitic,Fe nanoparticles were prepared,respectively.X-ray diffraction?X-ray?,transmission electron microscopy?TEM?,Raman spectroscopy?Raman?,Thermogravimetric Analysis?TGA?and comprehensive measurement system?ppms?were used to analyze the crystal structure,microstructure and properties of the sample.The results show that as the mass of dopamine added increases,carbon-encapsulated Fe₃O₄,martensitic,Fe nanoparticles are formed,and the mass proportion of carbon also increases.The average size is about 10 nm,and the saturation magnetizations were significantly lower than the bulk material due to the presence of non-magnetic carbon and the small size.3.On the basis of synthetic carbon-encapsulated martensite,by changing the amount of carbon source material added again,the results of synchrotron radiation XRD showed that martensite with different carbon solid solution content was synthesized.Within a certain range,as the amount of glucose added increased,the amount of solid-solution carbon in the martensite nanoparticles also increased.