NaLnF4:Yb3+/Er3+ 氟氧微晶玻璃原子尺度析晶机理与上转换发光性能的研究

Rare earth doped oxyfluoride glass ceramics containing NaLnF4 (Ln=Y, La, Lu) nanocrystals have attracted considerable interest in laser, three (3D) display and other fields, due to their low phonon energy, excellent quantum yields, high thermal and chemical stability. The network structure of glasses has significant influence on its up-conversion luminescent properties. Up to now, studies on network structure of oxyfluoride glass ceramics were mainly assumptions based on photoluminescent properties. In this project, we will prepare Er3+/Yb3+ co-doped transparent NaLnF4 (Ln=Y, La, Lu) oxyfluoride glass ceramics by conventional melt quenching method and following heat-treatment. In order to solve the problems that crystallization mechanism and local structural environments of rare earth ion are still unclear in up-converting luminescent glass-ceramics. Glass-ceramics with different compositions will be prepared under different heat treatment processes. And their structures will be studied at atomic level through solid-state NMR and paramagnetic resonance. The microstructure of network formers (Si4+, B3+), network intermediates Al3+, network modifiers Na+, fluoride, rare earth ions, etc. will be quantitatively analyzed. The influence of glass microstructure on the formation and growth of crystals will be systematically investigated. Also, the local environments and distribution of the luminescent ions in glasses will be explored. Finally, the mechanism of crystallization will be proposed. On the basis of fundamental understanding of the structures, the oxyfluoride glass-ceramics with excellent up-conversion quantum yields and high transparency will be expected to be obtained.

稀土掺杂的含NaLnF4 (Ln=Y, La, Lu)纳米晶的上转换发光微晶玻璃具有声子能量低、量子效率高、稳定性好等优异性能，在激光、三维显示等领域有广阔的应用前景。玻璃的微观网络结构对其上转换发光性能有非常重要的影响。目前关于氟氧玻璃的微观结构研究主要是通过光谱性能进行推测。本项目拟通过熔融淬冷及热处理制备NaLnF4氟化物纳米微晶玻璃，针对目前上转换发光微晶玻璃开发中微晶形成机理不清楚及稀土离子原子尺度的局部结构不明确等问题，运用固态核磁共振技术及顺磁共振技术对不同组分、不同热处理工艺的微晶玻璃进行原子级别结构解析，定量解析玻璃网络形成体（Si4+、B3+）、玻璃网络中间体Al3+、玻璃修饰体Na+、氟离子、稀土离子等的原子级微观结构，探讨玻璃微观结构对微晶形成与生长的影响，研究稀土离子在玻璃中的局部化学环境与分布规律，发现微晶形成机理，得到高发光效率、高透过率的上转换发光微晶玻璃。

稀土掺杂的氟氧微晶玻璃因其具有声子能量低、机械性能高、化学稳定性好的特点，在激光、三维显示、显微成像以及光学传感等领域的具有广阔的应用前景。目前对NaLnF4上转换微晶玻璃的研究主要集中在材料的制备及上转换发光性能研究。对微晶玻璃的原子级别网络结构以及稀土离子局部化学环境的研究却鲜有报道。准确地认识玻璃微观结构在原子尺度上的演化，有利于全面掌握析晶机理，实现对晶体的大小和晶型的控制来调控微晶的发光性能。本项目的研究内容包括稀土掺杂氟氧微晶玻璃及铋掺杂玻璃的固体核磁共振结构研究。利用各种先进的一、二维固态NMR技术与XPS技术从多个角度对不同玻璃组分、不同热处理工艺的微晶玻璃进行原子级别结构解析，探讨玻璃的微观结构对微晶的形成与生长的影响，以及稀土离子在玻璃中的局部化学环境与分布规律，并以此指导高发光效率、高透过率、高热稳定性和化学稳定性上转换发光微晶玻璃的设计和开发。