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

• 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

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+的上转换荧光和电子自旋共振(ESR)结果。 > 离子已被解释为这些材料中Er 3+ 离子的聚集，详细信息如下所述。干燥凝胶的热处理。 100Nb_2O_5-1Er_2O_3在500℃下得到玻璃体，而干燥的凝胶经550℃热处理后结晶成TT-Nb_2O_5相。晶体在805 nm激发下在544 nm处显示弱绿色上转换荧光，而玻璃体在544 nm处显示弱绿色上转换荧光。在晶体和玻璃中，在 4.2 K 下测量的 ESR 光谱都没有显示出信号。由于Er^<3+>在80 mT左右，表明Er^<3+>离子可以很好地分散在这些材料中而不会聚集。在玻璃中xAl_2O_3-(99-x)GeO_2-1Er_2O_3(x=0-5) ），在 525,550 和 660nm 处观察到由 Er^<3+> 离子引起的上转换荧光，这被指定为跃迁分别从激发态 ^2H_<11/2>、^4S_<3/2> 和 ^4F_<9/2> 到基态 ^4I_<15/2> 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> 能级的数量通过能量转移之间的交叉弛豫而增加。簇中紧密排​​列的 Er^<3+> 离子由于 Er^<3+> 而在 80 mT 处产生 ESR 信号，其强度随着 x 值的减小而降低，这意味着它也与聚类相关。由于顺磁偶极子-偶极子相互作用或簇状Er^3+离子之间的反铁磁相互作用，可能会减弱或消失。