稀土氢氧化物二维及三维结构调控及其光致发光性能

The studies on the synthesis, structure, and luminance property of rare-earth hydroxides that can be used as, or as the precursors for, luminescent materials are in the ascendant. Because the rare-earth ions bond with hydroxyl/H2O/oxygen ions in a high coordination number, the structures of the rare-earth hydroxides would be more complicated and changeable as compared with other metal hydroxides, eg. layered double hydroxides (LDHs). This project proposes to investigate extensively and intensively the design and control of the 2- and 3-dimensional structures and the photoluminescence properties of the rare-earth hydroxides, in order to clarify that (1) what other else structures could be there in the compounds besides the known layered and tunneled ones; (2) structural changes and “solidifications” of the 2-dimensional crystals (nanosheets) delaminated from layered rare-earth hydroxides (LRHs), as well as construction of 3-dimensionally structured luminescent materials; (3) structures and their changes as rare-earth elements are doping into each other or into other layered compounds that are represented by LDHs; and (4) the relationship between the structure and photoluminescence behavior for the products heated from the three kinds of the abovementioned ones as precursors and those transferred to rare-earth metal fluoride, and to obtain color-tunable, including white light, luminescent Materials. This study would increase the accumulation of knowledge in the areas such as inorganic materials chemistry, crystallography, soft chemistry, and photochemistry, concerning rare-earth compounds， and be, consequently, of theoretical and practical values.

作为发光材料及其前驱体的稀土氢氧化物的合成、结构、发光性能的研究方兴未艾。由于稀土金属离子通常采取高配位数与羟基/H2O/氧离子结合，因此与其他金属氢氧化物（如层状双金属氢氧化物，LDHs）相比，稀土氢氧化物的结构更为复杂多变。本项目提出从二维及三维结构上对稀土氢氧化物进行调控，并对其光致发光性能进行广泛深入研究，旨在厘清①稀土金属氢氧化物除了已知层状、通道状外，模板法合成还会有其他何种结构；②由层状稀土氢氧化物（LRHs）剥离得到的二维晶体（纳米片）的结构变化、自身的“固化”，及由其构筑三维结构的发光材料；③稀土元素互掺以及向其他以LDHs为代表的层状化合物中掺杂时的结构及其变化；④上述3种前驱物煅烧产物及向氟化物转化产物的结构与发光行为的关系；并获得颜色可调的、包括白光的稀土发光材料。研究将增加稀土化合物在无机材料化学、结晶学、软化学、光化学等领域的知识积累，具有理论和实际应用价值。

本项目针对稀土氢氧化物（LRHs）中稀土金属（Ln）通常采取高配位数而与羟基/H2O中的氧离子结合造成与其他金属氢氧化物（例如，层状双金属氢氧化物，LDHs）相比结构上更为复杂多变的问题，提出LRHs二维、三维结构及其发光性能调控的解决方案，并进行较为广泛深入地研究。项目的实施达成了研究目标：发明了制备多种稀土层状发光材料的新技术；结合层状材料及稀土的优势，获得具有特定性能的稀土发光材料；合成纳米片复合体；揭示稀土层状化合物种类、结构、以及配位与其发光性质之间的密切关系，为开发优良的稀土发光材料提供理论依据和实践指导。主要结果为，（1）搞清了Ln共掺杂的LRHs中的Ln的分布，发现能量传递主要在相邻层间进行而非层板内部；（2）研究了有机敏化剂在LRHs中的取向和能量传递，发现LEuH对MoO42ˉ的光学灵敏性检测；（3）研究了有机离子插层的LRHs一步法合成、结构及其发光性能；（4）搞清了LRHs剥离成二维晶体后的发光行为改变原因在于Ln配位状态的变化；（5）研究了LRHs、LDHs二维晶体的“固化”技术，获得了多种稀土发光材料，例如，固化了LDyH二维晶体的近白光发射，获得了LRHs的二维、三维胶体/光子晶体等；（6）研究了LRHs二维晶体的改性及其配列成三维晶体的结构、发光性能；（7）研究了Ln的掺杂对于层状钙钛矿结构和光学性能的影响，研究了LRHs与石墨烯等的纳米复合体；（8）还研究了LDHs等氢氧化物和MXenes等二维材料的制备和结构、三维晶体的组装、其他体系材料的制备，研究了相关的电化学、催化、吸附等性能。这些成果多数反映在标注基金资助的29篇学术论文和申请的28项发明专利中。培养了多名研究生、本科生，进行了国内外学术交流合作。本项目研究内容涉及无机合成化学、结晶学、软化学、胶体化学、光化学等领域，增加这些领域对LRHs、二维晶体有关的知识积累。