【作者】 贾潇；

【导师】 陈代荣；

【作者基本信息】 山东大学 ， 纳米材料化学， 2009， 博士

【摘要】 磁性材料由于其广泛的用途已越来越被人们所重视。本论文主要利用溶剂热方法合成铁基磁性纳米材料,内容包括合成单分散的铁酸盐纳米粒子及其表面改性,水中可分散的四氧化三铁纳米粒子的制备等,对纳米粒子尺寸、分散性的控制及形成机理进行了研究。并通过连续合成方法扩大了产物的产量,对磁性纳米材料的工业化发展有一定的促进作用。1.单分散铁酸盐纳米粒子的控制合成,磁性质及表面改性我们通过加热无机盐和SDBS的辛醇溶液,得到了在非极性溶剂中单分散的不同Co,Ni,Fe组分的Co_xNi_yFe_3-x-yO₄纳米粒子,其中x=0.6,0.3,0.2,0,y=0,0.6,0.7,0.8。合成的纳米粒子通过XRD,TEM,HR-TEM,SAED,IR,TG和其他分析手段进行了详尽的表征。合成纳米粒子的尺寸可通过改变反应时间来调节。通过跟踪反应过程提出了溶剂热反应中纳米粒子的形成机理。研究了纳米粒子的尺寸和组分对磁性质的影响,并对同一尺寸、不同组分的纳米粒子的磁性质进行了比较。此外,通过对合成的纳米粒子进行简单的醋酸洗涤,我们得到了水中分散的纳米粒子。本章的工作在于使用廉价无毒的无机盐前驱体合成了多组分,单分散的铁酸盐纳米粒子,精确控制了纳米粒子的尺寸,并通过表面改性的方法使其在非极性和极性溶剂中分散,扩大了其应用。2.绿色合成水中分散的四氧化三铁纳米粒子在本文中,我们使用无毒廉价的无水三氯化铁（FeCl₃）作为铁源,一缩二乙二醇（DEG）作为还原剂和溶剂,在无水醋酸钠（NaAc）的存在下合成了水中分散的四氧化三铁纳米粒子。和以往的方法比较,我们的合成方法中不存在有毒的无机离子或有机物原料,反应过程中不需要严格的气氛保护,合成出的纳米粒子在水中有很好的分散性,这大大扩大了合成产物在生物领域的应用。并且,我们合成的四氧化三铁纳米粒子的尺寸可通过简单的调节反应温度和时间来调节,尺寸在3-11纳米尺寸范围内可控。同时,为研究产物的形成过程,我们对反应进行了跟踪,提出了形成四氧化三铁纳米粒子的反应机理,并证实了合成产物的低毒性。3.连续溶剂热方法大量合成NiFe₂O₄和γ-Fe₂O₃纳米粒子通过连续溶剂热方法合成了单分散的磁性NiFe₂O₄和γ-Fe₂O₃纳米粒子。连续合成方法克服了以往合成中遇到的低产量的缺点,大大提高了生产效率,生产速率大于1g/h。合成的NiFe₂O₄可在环己烷中分散,而γ-Fe₂O₃纳米粒子则能在乙醇中稳定存在,这和我们使用的反应溶剂及表面活性剂有关。用XRD,TEM,HR-TEM,IR,TGA,ICP和其他技术对合成的磁性纳米粒子进行了表征。并对合成产物的磁性质进行了研究。反应参数如温度、浓度等对反应产物的影响也在文章中进行了详细的跟踪比较。更多还原

【Abstract】 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.更多还原