稀土掺杂钆铝石榴石的晶格稳定化及其荧光性能研究

The fluorescent properties of garnet-based luminscent materials (especially Y3Al5O12,YAG) needed to be further improved with the continuous development of display and lighting technology. Meanwhile, the low theoretical density of YAG hinders its development as scintillator materials. In view of this, pioneer investigations have been done on lattice stabilization of GdAG:Re3+ (Re=Tb/Eu,Tb/Ce) garnet via Lu3+ doping and based on which new phosphors (Gd,Lu)AG:Re3+ were synthesized by multicomponent carbonate technology in this project. Fluorescence parameters were measured using optical emission spectroscopy, fluorescence decay and other means. Combined with the fluorescence properties at low temperature and analysis of phonon band, the effects of crystal defects and microcosmic coordination symmetry on various aspects of luminscent performance were studied, and its action mechnism and Huang-Rhys factor were also determined; The flux impact on the material microstructure was revealed, and then the grain growth kinetics and optimal constitution of flux were determined; Utilizing the non-radiative energy transfer effect in the host lattice and selective excitation, luminescence intensity-tunable and color-tunable effectively have been successfully achieved, and the energy transfer mechanism will be disclosed. The project provides theoretical guidance for further optimization of properties of garnet-based luminscent materials.

随着显示和照明技术的不断发展，石榴石基荧光材料（尤其是Y3Al5O12，YAG）的荧光性能有待进一步提高，且YAG较低的密度亦阻碍了其作为闪烁体材料的发展。针对上述问题，本项目率先提出以Lu掺杂稳定GdAG:Re3+（Re=Tb/Eu, Tb/Ce）的晶格结构，以此为基础采用多组分碳酸盐沉淀技术合成高品质(Gd,Lu)AG:Re3+新型荧光材料。利用光致发射光谱、荧光衰减等手段，测量其荧光性能参数，结合材料的低温荧光特性和声子伴带分析研究晶体缺陷和Re3+的微观配位环境对荧光性能的影响及其作用机理，确定黄昆因子；揭示助熔剂对材料显微结构特征的影响，建立晶粒长大动力学规律，进而确定适于钆铝酸盐体系助熔剂的最佳构成；利用母晶格中稀土离子间的能量传递效应及选择性激发，实现材料荧光强度和荧光色的有效调控，揭示材料内部能量传递机制。该项目为进一步优化石榴石基荧光材料的光学性能提供了理论依据。

针对Y3Al5O12（YAG）石榴石基荧光材料的荧光性能有待提高，其较低的理论密度亦阻碍了其作为闪烁体材料的发展，本项目提出以Lu掺杂稳定GdAG:Re3+（Re= Tb, Eu, Tb/Eu, Tb/Ce）石榴石的晶体结构并以此为基础对(Gd,Lu)AG:Re3+体系进行光功能开发。该项目为进一步优化石榴石基荧光材料的光学性能提供了理论依据。项目的研究结果概述如下：.（1）采用碳酸 氢铵共沉淀法获得了形貌均匀、分散性良好的[(Gd1-xLu0x)1-yTby]AG（x=0.1-0.5, y=0.01-0.15）绿色荧光颗粒。Lu3+掺杂可实现GdAG晶格的有效稳定化，Lu最低掺杂量为～10 at%。 (Gd1-xLux)AG系荧光材料的密度较YAG体系具有较大的提升。该荧光材料的猝灭浓度为～10at%，猝灭机制为Tb3+间的相互作用。1500 ºC煅烧产物[(Gd0.9Lu0.1)0.9Tb0.1]AG具有优异的内部量子效率（83.4%）和外部量子效率（65.6%）。材料的晶格尺寸和荧光发射强度随着Lu3+的添加而降低。以GdAP:Tb3+为例，助熔剂的添加可进一步增强材料的荧光性能，助熔剂最佳配比为5wt%NaCl+95wt%Na2SO4，添加量为前驱体质量的2倍；.（2）对于[(Gd0.8Lu0.2)0.9-xTb0.1Eux]AG体系，Eu3+的橙红色发光因Gd3+→Eu3+和Tb3+→Eu3+能量传递而显著增强。x=0.03时的能量传递效率高达82%，能量传递机制为电偶极子-四偶极子互作用。通过调整Tb3+/Eu3+间的相对含量实现了绿-黄-橙红荧光色的有效调控；对于[(Gd0.8Lu0.2)0.99xCe0.01Tbx]AG体系，在不同激发波长下，材料发光呈现多样性。利用Gd3+→Ce3+和Tb3+→Ce3+能量传递可提高Ce3+的黄光发射，且该系荧光材料拥有更多的红光成份，更适宜用作暖光LED。Tb3+→Ce3+间的能量传递机制为电偶极子-电偶极子互作用；.（3）Al(NO3)3与NH4Al(SO4)2摩尔比为1.0，采用尿素均相沉淀法获得了[(GdxLu1-x)0.95Eu0.05]AG系红色球形荧光颗粒。颗粒尺寸随尿素浓度增加而减小。大尺寸颗粒呈现更优异的荧光性能和更短的荧光寿命。材料的荧光强度因Gd3+→Eu3+能量传递而随Gd含量