| Fe3O4 is a kind of typical materials in magnetic materials, and has unique physical and chemical properties. So the Fe3O4 nanoparticles have been widely used in electronic, magnetic, mechanical, chemical and biomedical fields, especially the Fe3O4 nanoparticles have good biocompatibility, and have a great influence on the development of the biological medicine field. And decentralized state and surface properties of Fe3O4 magnetic nanoparticles have a great influence on its application. In recent years, with the deepening of the research, surface modification of Fe3O4 nanoparticles and design of Fe3O4 composite nanoparticles with specific surface properties become the research frontiers and focuses for the Fe3O4.Research work of this article is mainly about the good performance of Fe3O4 magnetic nanoparticles preparation, surface modification and functionalization, relates to the preparation of magnetic Fe3O4 nanoparticles by chemical coprecipitation method,dispersion, surfactant to improve the surface properties and morphology of nanoparticles, the core-shell structure superparamagnetic Fe3O4@Si O2 composite nanoparticles was prepared with the improved St?ber method, and the products were characterized by FT-IR, SEM, XRD, PPMS and other testing methods. The concrete contents include: 1 Fe3O4 magnetic nanoparticles was surface modificated with small molecular and characterizationFe3O4 nanoparticles with the average particle size of 16.5 nm have superparamagnetism, morphology of irregular spherical was preparated with chemical coprecipitation; Fe3O4 nanoparticles were surface modified with citric acid and oleic acid as surfactant respectively, describes the mechanism.The results show that: investigate the citric acid concentration and reaction temperature on the effects of the ferroferric oxide modified found that citric acid concentration and reaction temperature will affect the Fe3O4 nanoparticles morphology, crystalline and magnetism performance;when using citric acid modified Fe3O4 nanoparticles, the reaction temperature is 40℃, citric acid and total iron ion of the amount of substance ratio is 0.2, the morphology and properties of the modified nanoparticles obtained is the best.Studied the effect of reaction temperature on the Fe3O4 modification effect,when the reaction temperature on 60℃, the oleic acid modified Fe3O4 nanoparticles better dispersion, small particle size and uniform has observed by scanning electron microscope. 2 Fe3O4 magnetic nanoparticles were coated with inorganic small molecule(Si O2) and characterizedWith citric acid modified Fe3O4 nanoparticles as the seed, with the improved St?ber method of preparation of magnetic strength, high thermal stability of Fe3O4@ Si O2 composite nanoparticles. Set different parameters in the process of the experiment, to study the effect of TEOS concentration, magnetic fluid concentration, ammonia concentration and alcohol water ratio of experimental conditions on the morphology and properties of Fe3O4@Si O2 composite nanoparticles, respectively. The results show that: the Si O2 layer can obviously improve the dispersion of Fe3O4 nanoparticles; size and magnetic properties of Fe3O4@Si O2 composite particles can by changing the concentration of TEOS、magnetic fluid and ammonia to adjust; when the concentration of TEOS is 0.02mol/L, Fe3O4 particles are completely coated, the saturation magnetization intensity of composite particles reached 30.9emu/g, and gradually reduce with increase of TEOS concentration, the coercive force constant, maintain good superparamagnetism; The concentration of Fe3O4 had over the general assembly will reduce the dispersion of Fe3O4@Si O2 composite particles; when the ammonia concentration is 0.3mol/L, the preparation of composite particles saturated magnetization intensity maximum is 38.6emu/g, the concentration is too high or too low, the saturation magnetization of composite particles will reduce; The size of ethanol water ratio affects the polarity of solution, and then affects the stability of the Fe3O4 particles; when the Fe3O4 nanoparticles and Fe3O4@Si O2 composite particles after heat treatment, according to the X ray diffraction diagram, compared with the pure Fe3O4 nanoparticles, the thermal stability of the composite particles is better. |
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