铁基化合物纳米材料的控制合成及其性能研究

发布时间：2018-05-22 11:51

本文选题：氟化亚铁 + 碳化铁　；参考：《浙江工业大学》2017年硕士论文

【摘要】：铁基化合物纳米材料因其独特的磁性能、电化学性能和良好的生物相容性,被广泛应用于电极材料、药物输送、磁共振成像与生物分离等领域。其中,氟化亚铁纳米颗粒是常用的反铁磁性材料,碳化铁纳米颗粒是一种典型的铁磁性纳米材料。制备这两种纳米材料并研究其各方面性能对于理解铁基化合物纳米材料具有重要作用。纳米材料的物理化学性能与其颗粒的形貌、尺寸有着密切的关系。因此,可控制备具有特殊结构的单分散铁基化合物纳米材料并研究其结构依赖的性能成为近几年的热点。液相热分解法能通过控制形核、生长过程调控纳米材料的形貌,是目前制备单分散纳米材料常用手段之一。因此,本文采用液相热分解法制备氟化亚铁、碳化铁两种纳米材料。本论文旨在通过合理的技术路线设计,合成形貌结构新颖的氟化亚铁和碳化铁纳米材料,并研究其在磁共振成像与电池方面的应用。懫用X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、能谱仪(EDS)、等离子体电感耦合-原子发射光谱(ICP-AES)、磁共振成像(MRI)、循环伏安(CV)、电化学阻抗(EIS)等测试手段对合成的材料的结构、形貌、性能进行研究。本文的具体研究内容如下:(1)采用液相热分解法制备得到了尺寸形貌可控的FeF_2纳米颗粒。以乙酰丙酮铁为前驱体,氟化铵为反应物,油胺同时作为溶剂、表面活性剂与还原剂,在惰性气体保护下调节反应时间与温度,制备得到尺寸为100-200 nm的FeF_2纳米立方团簇。其中,氟离子在体系中充当交联剂。在反应体系中加入适量油酸,可得到粒径为十几纳米大小的FeF_2纳米颗粒。作为T_1加权磁共振成像(MRI)造影剂,粒径为100 nm的FeF_2纳米颗粒表现出较好的成像效果,其纵向弛豫效能值为1.08 m M~(-1)s~(-1)。(2)研究了FeF_2纳米团簇作为锂离子电池正极材料的性能,探讨了碳材料的引入对其电池性能的影响。分别采用有机物混合烧结和石墨烯超声物理吸附两种手段对材料表面进行碳层包覆。聚苯乙烯(PS)与FeF_2混合烧结成功在FeF_2表面形成碳层,提高了导电性和循环稳定性,电荷转移反应电阻降为140Ω,并在30次循环后保有65%的初始放电容量。但由于高温烧结氧化铁相的引入,FeF_2/C的初始放电容量降低为213 m Ah g~(-1),约为理论容量的37%(571 m Ah g~(-1))。超声负载石墨烯使材料电荷转移反应电阻降为60Ω。FeF_2/G复合物的初始放电容量475 m Ah g~(-1),约为理论容量的83%。(3)采用卤素离子诱导的液相热分解法,以羰基铁为前驱体,油胺为表面活性剂,十八胺为溶剂在合成bcc-Fe晶核的基础上碳化,两步法制备了Fe_2C(六方晶系、单斜晶系)和Fe_5C_2(单斜晶系)纳米颗粒。卤素离子的加入是碳化过程中调控Fe-C相的关键。Fe_2C可在碳化过程无卤素参与下得到,其相转化受热力学控制,在260-300℃范围内得到的为六方晶系,310℃后转化为单斜晶系。碳化过程中卤素离子的引入使得Fe原子与C原子之间的结合力减小,故可得到Fe_5C_2。实验发现,改变羰基铁加入量、碳化时间、卤素离子添加量对产物相结构无显著影响,但会部分改变产物形貌。对Fe_2C与Fe_5C_2两种碳化铁纳米材料进行T_2加权磁共振成像性能研究,发现其均表现出良好的成像效果,其横向弛豫效能值分别为357 m M~(-1)s~(-1)和192 m M~(-1)s~(-1),均高于商用氧化铁纳米颗粒造影剂,是有前景的T_2磁共振成像造影剂。
[Abstract]:Iron based compound nanomaterials are widely used in the fields of electrode materials, drug delivery, magnetic resonance imaging and biological separation because of their unique magnetic properties, electrochemical properties and good biocompatibility. Among them, ferrous fluoride nanoparticles are commonly used antiferromagnetic materials, and iron carbide nanoparticles are a typical ferromagnetic nano material. It is important to prepare these two nanomaterials and study their properties for understanding the iron based compound nanomaterials. The physical and chemical properties of the nanomaterials are closely related to the morphology and size of the particles. Therefore, the mono dispersed iron based nanocomposites with special structures can be controlled and their structural dependence can be studied. Performance has become a hot spot in recent years. Liquid phase thermal decomposition (liquid-phase thermal decomposition) can control the morphology of nanomaterials by controlling the nucleation and growth process. Therefore, the liquid phase thermal decomposition method is used to prepare ferrous fluoride and two kinds of nanomaterials. The purpose of this paper is to establish a reasonable technical route. To synthesize the novel morphologies of ferrous fluoride and iron carbide nanomaterials, and to study their applications in magnetic resonance imaging and batteries. X ray diffraction (XRD), transmission electron microscopy (TEM), X ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), plasma inductively coupled atomic emission spectroscopy (ICP-AES), magnetic resonance imaging (MRI), and circulation Voltammetry (CV), electrochemical impedance (EIS) and other testing methods have been used to study the structure, morphology and properties of the synthesized materials. The specific contents of this paper are as follows: (1) the size and morphology controlled FeF_2 nanoparticles were prepared by the liquid phase thermal decomposition method. A FeF_2 nanocluster with a size of 100-200 nm was prepared by adjusting the reaction time and temperature under the protection of inert gas with the active agent and reducing agent. Among them, the fluorine ion acted as a crosslinker in the system. A suitable amount of oleic acid was added to the reaction system, and the size of FeF_2 nanoparticles with a size of more than ten nanometers was obtained. As a T_1 weighted magnetic resonance formation Like (MRI) contrast agent, FeF_2 nanoparticles with a particle size of 100 nm showed good imaging results, and their longitudinal relaxation efficiency was 1.08 m M~ (-1) s~ (-1). (2) the performance of FeF_2 nanoclusters as cathode materials for lithium ion batteries was studied. The effects of the introduction of carbon materials on their battery performance were investigated. Organic compound sintering and stone were used respectively. The surface of the material is coated with carbon layer by two means of ultrasonic physical adsorption. The mixed sintering of polystyrene (PS) and FeF_2 has successfully formed carbon layer on the surface of FeF_2. The conductivity and cyclic stability are improved, the charge transfer reaction resistance is reduced to 140 Omega, and the initial discharge capacity of 65% after 30 cycles is preserved. But due to the high temperature sintering of iron oxide phase The initial discharge capacity of FeF_2/C was reduced to 213 m Ah g~ (-1), about 37% of the theoretical capacity (571 m Ah g~ (-1)). The ultrasonic load graphene made the charge transfer reaction resistance of the material to the initial discharge capacity of 60 Omega.FeF_2/G compound 475 m Ah (3), about the theoretical capacity (3) using halogen induced liquid thermal decomposition method. Carbonyl iron is a precursor, oleamine is a surfactant, eighteen amine is used as a solvent to carbonization on the basis of the synthesis of bcc-Fe nucleation. Fe_2C (six square crystal system, monoclinic system) and Fe_5C_2 (monoclinic) nanoparticles are prepared by two step method. The addition of halogen ions is the key to the regulation of Fe-C phase in carbonization process, which can be obtained by the participation of halogen free process in carbonization process. When the phase transformation is controlled by thermodynamics, the six square crystal system is obtained in the range of 260-300 C and converted to monoclinic system at 310 C. The introduction of halogen ions in the carbonization process reduces the binding force between the Fe atom and the C atom. Therefore, the Fe_5C_2. experiment can be found to change the amount of carbonyl iron, the carbonization time, and the addition of halogen ions to the products. The phase structure has no significant influence, but the morphology of the product is partly changed. The T_2 weighted magnetic resonance imaging properties of two kinds of Fe_2C and Fe_5C_2 nano materials are studied. It is found that both of them exhibit good imaging results, and their transverse relaxation efficiency values are 357 m M~ (-1) s~ (-1) and 192 m M~ (-1) s~, respectively, which are higher than those of commercial iron oxide nanoparticles. The shadow agent is a promising T_2 magnetic resonance imaging contrast agent.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;TQ138.11

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