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Preparation of Upconversion Fluorescent Glasses by the Sol-Gel Method and Their Properties

溶胶-凝胶法制备上转换荧光玻璃及其性能

基本信息

批准号：
08650790
负责人：
KOJIMA Kazuo
金额：
$ 0.77万
依托单位：
Ritsumeikan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650790/
关键词：
Sol-Gel Method Erbium Ion Niobium Oxide Germanium Oxide Aluminum Oxide Upconversion Fluorescence ESR Clustering 酸化ゲルマニウムガラス

项目摘要

Near infrared to visible upconversion fluorescence has been observed in Er^<3+> doped polycrystalline Nb_2O_5 and Al_2O_3-GeO_2 glasses prepared by the sol-gel method. The results of upconversion fluorescence and electron spin resonance (ESR) for Er^<3+> ions have been interpreted in terms of clustering of Er^<3+> ions in these materials. The details are described below.Heat-treatment of a dried gel 100Nb_2O_5-1Er_2O_3 at 500ﾟC gave a glass, whereas the dried gel crystallized into the TT-Nb_2O_5 phase by the heat-treatment at 550ﾟC.The crystal showed weak green upconversion fluorescence at 544 nm under 805 nm excitation, while the glass did not. In both the crystal and glass, ESR spectra measured at 4.2 K showed signals due to Er^<3+> at about 80 mT,indicating that Er^<3+> ions may be well dispersed in these materials without clustering.In glasses xAl_2O_3-(99-x)GeO_2-1Er_2O_3(x=0-5), upconversion fluorescence due to Er^<3+> ions was observed at 525,550, and 660nm, which is assigned to the transition to the ground state ^4I_<15/2> from excited states ^2H_<11/2>, ^4S_<3/2>, and ^4F_<9/2>, respectively. The relative intensity of the 660-nm fluorescence increases with decreasing the value of x. This is because clustering of Er^<3+> ions occurs and then the populations of the ^4F_<9/2> level increases by the energy transferring cross relaxation between close-lying Er^<3+> ions in a cluster. An ESR signal at 80 mT due to Er^<3+> decreases in intensity with decreasing the value of x, implying that it is also associated with clustering. The ESR signal may weaken or disappear due to the paramagnetic dipole-dipole interaction or the antiferromagnetic interaction between clustered Er^<3+> ions.

采用溶胶-凝胶法制备的Er^3+掺杂多晶Nb_2O_5和Al_2O_3-GeO_2玻璃中观察到近红外到可见光的上转换荧光。 Er 3+ 离子的上转换荧光和电子自旋共振(ESR)结果已根据这些材料中Er 3+ 离子的聚集来解释。详细情况如下所述。干燥凝胶100Nb_2O_5-1Er_2O_3在500℃下热处理得到玻璃体，而干燥凝胶在550℃下热处理结晶成TT-Nb_2O_5相。在805nm激发下，晶体在544nm处显示弱绿色上转换荧光，而玻璃则没有。在晶体和玻璃中，在4.2 K下测量的ESR光谱在约80 mT处显示出由Er^<3+>引起的信号，表明Er^<3+>离子可能很好地分散在这些材料中而没有聚集。在玻璃xAl_2O_3-(99-x)GeO_2-1Er_2O_3(x=0-5)中，观察到由Er^<3+>离子引起的上转换荧光 525,550 和 660nm，分别指定从激发态 ^2H_<11/2>、^4S_<3/2> 和 ^4F_<9/2> 到基态 ^4I_<15/2> 的跃迁。 660 nm 荧光的相对强度随着 x 值的减小而增加。这是因为Er^<3+>离子发生聚集，然后^4F_<9/2>能级的数量通过簇中紧密分布的Er^<3+>离子之间的能量转移交叉弛豫而增加。由于Er ^ 3+ 导致的80mT的ESR信号强度随着x值的减小而减小，这意味着它也与聚类相关。 ESR信号可能由于顺磁偶极-偶极相互作用或簇状Er 3+ 离子之间的反铁磁相互作用而减弱或消失。