Controlled Synthesis And Properties Characterization Of Magnetic Ferrite Nanomaterials

Magnetic materials have attracted much interest because of their extensive use in many fields.In this paper,the main contents are related to preparation of iron-based magnetic nano-materials by a solvothermal method,including synthesis of magnetic product such as monodisperse ferrite nanoparticles,the water-dispersible Fe₃O₄ nanoparticles;the investigation of controlling mechanism for the size,dispersibility and formation of the nanoparticles.And mass production of magnetic nanoparticles has been carried out by continuous synthesis,which has a certain role in promoting the industrial development of magnetic nano-materials.1.Monodispersed Co,Ni-ferrite Nanoparticles with Tunable Sizes:Controlled Synthesis,Magnetic Properties and Surface ModificationFerrite(Co_xNi_yFe_3-x-yO₄,x=0.6,0.3,0.2,0,y=0,0.6,0.7,0.8)nanoparticles monodispersed in nonpolar solvents have been prepared with different Co,Ni,Fe compositions by heating mixtures of inorganic salts and SDBS in n-octanol.The as-prepared nanoparticles were characterized in detail by XRD,TEM,HR-TEM, SAED,IR,TG analysis and other techniques.The nanoparticle sizes could be tuned by adjusting the reaction time.The formation mechanism of the nanopartieles during the solvothermal process is proposed based on the experimental results.The effects of size and composition of the nanoparticles on magnetic properties were investigated, and the magnetic properties of nanoparticles with the same size but different compositions were compared.Furthermore,water-dispersible nanoparticles were obtained by simply washing the as-prepared nanoparticles with acetic acid.The objective of this work is to develop a route to synthesize monodispersed ferrite nanoparticles in both nonpolar and polar solvents with multiple compositions and precisely controlled sizes using low-cost inorganic salts as precursors.The acetate-modified nanoparticles might have significant broader applications.2.Environmentally-Friendly Preparation of Water-Dispersible Magnetite NanoparticlesHerein,an improved polyol reduction process to water-dispersible Fe₃O₄ nanoparticles using the cost-effective anhydrous FeCl₃ as the iron source and diethylene glycol(DEG) as the reductant and solvent in presence of anhydrous CH₃COONa was designed.Compared to the previous reports,no toxic inorganic ions or organic species existed,no atmosphere potection was needed,and the as-prepared Fe₃O₄ nanoparticles exhibited excellent water-dispersibility,favoring application in biological science.The particle size(3-11 nm) can be tuned by simply adjusting the reaction temperature and time.The formation mechanism of Fe₃O₄ nanoparticles is proposed and their low cytotoxicity has also been proved.3.Mass production of NiFe₂O₄ andγ-Fe₂O₃ nanoparticles by continuous solvothermal synthesisMonodispersed magnetic NiFe₂O₄ andγ-Fe₂O₃ nanoparticles have been prepared by a continuous solvothermal method.We overcame the usual low yield shortcomings for synthesizing high quality nanoparticles by continuous synthesis using the previous system we had reported.Generally,the hourly output of our magnetic product was more than 1g.NiFe₂O₄ nanoparticles we prepared can disperse in cyclohexane, andγ-Fe₂O₃ nanoparticles can be stable in ethanol,which may be caused by the different solvent and surfactant we used in the reaction system.The as-prepared nanoparticles were characterized by XRD,TEM,HR-TEM,IR,TGA,ICP and other techniques.Magnetic properties of the as-prepared magnetic nanoparticles were studied.The effect of the reaction parameters such as temperature,concentrations were also investigated in detail.