【作者】 罗秋玲；

【导师】 卢冠忠；

【作者基本信息】 华东理工大学 ， 工业催化， 2012， 博士

【摘要】 介孔材料以其有序的孔道结构、多样的拓扑方式、可调的孔径尺寸、可控的形貌特征、较高的比表面积和较大的孔容等优势,在催化、生物医药、能源、传感、材料合成等领域得到了广泛的应用。近几年介孔材料与光、电、磁等功能相结合,使其在吸-脱附、贮存、传输、示踪、靶向等方面发挥了更大的作用。稀土元素具有特殊的电子和光学性质,是发光材料的重要组分。本文将稀土材料自身的发光属性与介孔、有序排列的结构性质相结合,开展介孔发光材料的合成研究,以拓展稀土和介孔材料合成的新方法和应用的领域。1、研究了有序介孔结构的稀土磷酸盐的合成和掺杂不同稀土离子的发光性能。在硬模板法制备介孔材料方法的基础上,提出了多组分不溶性固体化合物前驱体溶液制备的新方法,从而使不溶性固体化合物溶解后得到均一稳定的前驱体溶液,通过毛细管作用使前驱体进入硬模板孔道中积累、沉淀,经过焙烧并去除硅模板后得到反相复制的有序介孔磷酸钇,通过掺杂铕、铽、铈不同发光离子,得到发红光、绿光、蓝光三种介孔稀土YPO4: Ln3+(Ln: Eu,Tb和Ce),通过改变Ln离子的掺杂浓度,并可对稀土磷酸盐发光性能进行调控。2、利用改进的硬模板纳米晶化法合成了具有二维六方(p6mm)和三维立方(Ia3d)结构的介孔稀土钒酸盐,研究了不同介孔拓扑结构对介孔钒酸钇(铕)发光性能的影响。研究表明,两种介孔钒酸钇(铕)在达到最强发光时掺Eu3＋的浓度是不同的；在三维立方介孔钒酸钇(铕)中,Eu3＋最适宜浓度为8%(mol)；在二维六方介孔钒酸钇(铕)中,Eu3＋最适宜浓度为5%(mol)。分析了不同介孔结构造成的缺陷、接受光照有效面积等对荧光中心离子(Eu3+)产生的影响。3、研究了有序层状有机-无机杂化稀土磷酸铈(铽)的合成和发光性质。研究表明,在合成过程中用极性较大的水作溶剂时,制备的样品具备良好的结晶性和有序的层状结构,其发光强度远高于用沉淀法制备的固体粉末和用极性较小的乙醇作溶剂制备的样品。说明有序的层状结构和良好的结晶有利于无机部分稀土磷酸铈(铽)的发光。同时,这种长烷基的杂化发光材料还具有亲油性,当分散于有机溶剂时能发出较强的绿光。4、稀土氧化物负载于球形、多面体、棒状多种形貌的介孔二氧化硅的复合物制备。通过改变温度、负载量等因素考察载体二氧化硅的形貌、孔道结构对负载物发光性能的影响,结果发现焙烧温度对几种不同形貌复合物的影响大致相同,温度过高会造成孔道塌陷,经1000℃焙烧后,介孔被破坏和稀土氧化物与模板发生相变。球形载体对稀土氧化物负载能力最小,棒状载体负载能力最大,多面体载体的负载能力介于前两者当中。稀土氧化物在不同的载体上的发光情况具有不同的规律。介孔材料的拓扑结构多种多样,为了适应未来应用中更精细、更专一的需求,不同的结构带来的差异和影响需要进一步研究。本文对具有多种拓扑结构的介孔稀土复合发光材料进行了研究和性能的比较,希望为稀土材料的多功能化制备做些有益的工作。更多还原

【Abstract】 Mesoporous materials with the ordered mesopores, various topologies, tailored pore size, controllable morphologies, high surface and large pore volume, can be wide used in the catalysis, bio-medicine, energy, sensors, material synthesis, and so on. In recent years, mesoporous materials combined with the optical, electrical and magnetic properties play an important role in the absorption/desorption, storage, carrier, tracing, and targeted. Rare earth elements with special electronic and optical properties are the important component of photoluminescent materials. Therefore, in this thesis the synthesis methods for the rare earth mesoporous materials combined with the luminescent property were studied, in order to get a new approach to prepare the rare earth mesoporous materials for more potential application.1. Studies on the synthesis of mesoporous rare earth phosphates and their luminescence properties. Based on the nanocasting route by hard-template, an improved method for preparing mesoporous materials has been brought forward by solving the indiscerptible solid precursor to get a uniform and stable precursor solution with soluble multi-component. During the infiltration process to progressively concentrate the precursor ions, capillarity drives the formation of precipitation inside the channels of silica hard template; after calcination and removing the hard template, mesoporous ordered YPO4 replica by reverse has been prepared. After YPO4 was doped with the appropriate lanthanide ion (such as Eu3+, Tb3+, and Ce3+), mesoporous YPO4:Ln3+ materials with the tunable intense optical properties (such as red, green and blue emission) were obtained.2. Synthesis of hexagonal (p6mm) and cubic (Ia3d) rare earth vanadate by means of improved nanocasting route by hard-template and study on the photoluminescence change between different topology mesostructures of YVO4:Eu3+. The results show that, there are different quenching concentrations for two cubic and hexagonal mesoporous YVO4:Eu3+ samples, for instance, the highest PL intensity of the cubic mesoporous YVO4:Eu3+(8 mol%) can be observed and the hexagonal one is 5 mol% Eu3+, which suggest that the different mesoporous channels of the cubic and hexagonal mesoporous YVO4:Eu3+ lead to different produced defaults and available surfaces for absorption of the UV light by the mutual interaction Eu3+ ions. 3. Study on the synthesis of layered ordered organic-inorganic hybrid rare earth materials and their luminescence properties. The results show that, the sample obtained under polar aqueous solution by template assembly has higher ordered layered structure, better crystallinity and stronger luminescent intensity than the samples obtained in ethanol solvent and the sample prepared by a precipitation method. It suggests that higher ordered layered structure and better crystallinity take benefit of the luminescence of the hybrid rare earth materials. And this long alkyl hybrid luminescent material with lipophilicity shows good green luminescent intensity in oil medium.4. Synthesis of Ln2O3@SiO2 compounds that the rare earth oxide supporting in spherical, polyhedral, and rod-like shape silica. The effect of silica supports with different morphology and channel on Ln2O3 luminescent properties was investigated by changing the temperature and Ln loading concentration. The results show that the effect of calcination temperature is almost same for the different complexes, that is, high temperature results in collapse of mesoporous structure and the phase transition of rare earth oxides and silica support after calcination at 1000℃. The loading amount of rare earth oxides is the minimum on the spherical silica support, the maximum on the rod silica support, and between the former two on the polyhedron silica support. It means that there are different luminescence properties corresponding to the rare earth oxides loaded on the different morphological silica supports.Mesoporous materials will satisfy more ingenious and specific requirement in future applications, and the diversified materials with different topological mesostructures should be further studied. In this thesis, the rare earth materials with multiple topological mesostructures have been studied and compared in the luminescent properties, which is very meaningful for the preparation and utilization of multi-functional rare earth materials.更多还原