尖晶石型锌铁氧体的生长调制及其机理的原位研究

发布时间：2018-07-10 00:47

本文选题：锌铁氧体 + 纳米簇　；参考：《扬州大学》2017年硕士论文

【摘要】：尖晶石型铁氧体因其优越的性能而被广泛应用在催化、磁存储、生物医药等领域。如何在保持材料超顺磁性(小颗粒)的同时,有效提高其磁化强度是影响该类型材料研发的一个关键科学问题。本论文以锌铁氧体(ZnFe2O4)为目标产物,通过改变产物中的Fe、Zn离子摩尔比、添加多齿配体等,制备了不同形貌(簇状、纳米片、单分散纳米颗粒)的高饱和磁化强度的锌铁氧体。应用原位微量热技术研究了其相应的形成机理。为研制超顺磁、高饱和磁化强度的尖晶石型纳米材料提供理论指导和科学依据。同时,通过添加六齿配体EDTA,成功制备了 ZnFe2O4/ZnO共存的磁性纳米材料。本文的主要研究内容和结论如下:1、选择组成为Zn0.2Fe2.8O4的超顺磁、高饱和磁化强度的纳米簇作为目标产物,通过原位量热并技术结合XRD、ICP-AES、TEM、XPS、FTIR等表征手段,深入探索纳米簇的形成机理。实验结果表明,体系中的Fe3+首先和HOCH2CH2OH反应生成Fe(OCH2CH2OH)3,然后部分 Fe(OCH2CH2OH)3 中的 Fe3+ 被 Zn2+ 替代,形成Zn(OCH2CH2OH)2。Fe(OCH2CH2OH)3和Zn(OCH2CH2OH)2 聚合作为凝胶因子,形成凝胶。随着反应温度升高,氢键被破坏,凝胶会转化成溶液。该过程发生了取代反应,生成了(Fe,Zn)OOH,其中-OCH2CH2O-作为桥联基团与Fe3+和Zn2+成键,诱导了簇状结构的形成。然后簇状(Fe,Zn)OOH脱水生成了簇状α-Fe203,最后转变为簇状Zn0.2Fe2.8O4。并通过加入EDA抑制醇盐的生成和聚合,进一步证明是聚合物的形成促使产物形成簇状结构,-OCH2CH2O-的桥联作用是形成簇状结构的关键。对磁性纳米簇形成机理的研究,将为研制该类型材料提供思路和理论基础,为类似的科学问题提供实验依据。2、通过简单的一步溶剂热法合成了具有高饱和磁化强度和大表面积的单分散Zn掺杂Fe3O4磁性纳米片。使用原位微量热法,结合XRD、ICP-AES、XPS、FTIR、TEM等表征手段详细研究了 EDA调控下Zn掺杂Fe304磁性纳米片的形成机理。结果表明EDA改变了产物的生成机理。体系中Fe(EDA)3]3+和[Zn(EDA)3]2+配合物的形成,降低了游离Fe3+和Zn2+浓度,抑制了部分反应的发生,并导致部分反应在更高的温度发生。同时,Zn掺杂Fe3O4的(111)面变得稳定,这诱导了纳米片的形成。具有高饱和磁化强度和大表面积的Zn掺杂的Fe304纳米片在不同领域,如吸附、生物分子分离和药物靶向传递中,具有潜在的应用价值。3、通过一步溶剂热法合成了表面积较大的ZnFe204/Zn0磁性复合材料。利用原位微量热法研究了 ZnFe2O4/ZnO复合材料的形成机理。Fe3+-EDTA和Zn2+-EDTA配离子的形成,降低了游离Fe3+和Zn2+浓度,抑制了醇盐的形成。同时,适量的EDTA作为配体,可以吸附在晶体的表面,从而使得临近的晶核在氨基和羧基的作用下,自组装成球,与第二章中-OCH2CH2O-类似。制备的ZnFe2O4/ZnO磁性复合材料因为比表面积较大且分散性好,在吸附、光催化等方面有潜在的应用价值。
[Abstract]:Spinel ferrite is widely used in catalysis, magnetic storage, biomedicine and other fields because of its superior performance. How to improve the magnetization while keeping the material superparamagnetism (small particle) is a key scientific problem that affects the research and development of this kind of material. In this paper, zinc ferrite (ZnFe _ 2O _ 4) was used as the target product. High saturation magnetization zinc ferrites with different morphologies (clusters, nanoparticles and monodisperse nanoparticles) were prepared by changing the molar ratio of Fe ~ (2 +) and polydentate ligands. The formation mechanism was studied by in situ microcalorimetry. It provides theoretical guidance and scientific basis for the development of spinel nanomaterials with super paramagnetic and high saturation magnetization. At the same time, the magnetic nanomaterials of ZnFe2O4 / ZnO were successfully prepared by adding hexagonal ligand EDTA. The main contents and conclusions of this paper are as follows: 1. The ultraparamagnetic and high saturation magnetization nanoclusters composed of Zn0.2Fe2.8O4 are selected as the target products. The formation mechanism of nanoclusters is further explored by means of in-situ calorimetry and in situ calorimetry combined with XRDICP-AESTEMP-TEMPS FTIR. The experimental results show that Fe _ 3 reacts with Hoch _ 2CH _ 2OH to form Fe (OCH _ 2CH _ 2OH) _ 3, and then Fe _ 3 in Fe (OCH _ 2CH _ 2O _ H) _ 3 is replaced by Zn _ 2 to form a gel by polymerization of Zn (OCH2CH2OH) _ 2.Fe (OCH2CH2OH) _ 3 and Zn (OCH2CH2OH) _ 2 as gel factors. As the reaction temperature increases, the hydrogen bond is broken and the gel is converted into a solution. The substitution reaction took place in this process, resulting in the formation of (Fezn) OOH, in which -OCH _ 2CH _ 2O- was used as a bridging group to bond with Fe _ 3 and Zn _ 2, which induced the formation of cluster structure. Then a cluster 伪 -Fe 203 was formed by dehydration of cluster (Feo Zn) OOH, and finally transformed into cluster Zn 0.2Fe 2.8O 4. By adding EDA to inhibit the formation and polymerization of alcohol salt, it is further proved that the bridging action of the product to form cluster structure is the key to the formation of cluster structure. The study of the formation mechanism of magnetic nanoclusters will provide a theoretical basis for the development of this type of materials. In order to provide experimental basis for similar scientific problems, monodisperse Zn doped Fe _ 3O _ 4 magnetic nanocrystals with high saturation magnetization and large surface area were synthesized by a simple solvothermal method. In situ microcalorimetry was used to study the formation mechanism of Zn doped Fe 304 magnetic nanocrystals under the control of EDA by means of in situ microcalorimetry combined with XRDX ICP-AESX FTIR TEM. The results showed that EDA changed the formation mechanism of the product. The formation of Fe (EDA) _ 3] _ 3 and [Zn (EDA) _ 3] _ 2 complexes decreases the concentration of free Fe _ 3 and Zn _ 2, inhibits the occurrence of partial reactions and results in partial reactions at higher temperatures. At the same time, the (111) surface of Zn doped Fe _ 3O _ 4 becomes stable, which induces the formation of nanocrystals. Zn doped Fe 304 nanocrystals with high saturation magnetization and large surface area are found in various fields, such as adsorption, biomolecular separation and drug targeting transport. ZnFe204 / Zn0 magnetic composites with large surface area were synthesized by one step solvothermal method. In situ microcalorimetry was used to study the formation mechanism of ZnFe _ 2O _ 4 / ZnO composites. The formation of Fe _ 3-EDTA and Zn _ 2-EDTA complex ions decreased the concentration of free Fe _ 3 and Zn _ 2 and inhibited the formation of alcohol salts. At the same time, the appropriate amount of EDTA as ligand can be adsorbed on the surface of the crystal, so that the adjacent nuclei can self-assemble into spheres under the action of amino and carboxyl groups, which is similar to that of -OCH2CH2O- in Chapter 2. The ZnFe _ 2O _ 4 / ZnO magnetic composites have potential applications in adsorption and photocatalysis because of their large specific surface area and good dispersion.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1

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