ZnO含量对Tb^(3+)掺杂ZnO-B_2O_3-SiO_2玻璃余辉性能及光致变色的影响

Influence of ZnO Concentration on Persistent Luminescence Properties and Photochromism of ZnO-B_2O_3 - SiO_2 Glasses Doped with Tb^(3+)

选择制备了Tb_(3+)掺杂的不同ZnO含量、组成为xZnO-[(100-x)/2]B_2O_3-[(100-x)/2]SiO_2(x=55,60,65,70)的ZBS玻璃。并通过光致发光光谱、余辉衰减曲线、热释光谱以及紫外-可见吸收光谱系统地研究了该玻璃系统的余辉发光特性和光致变色现象。随着ZnO含量的增加,基质玻璃中Tb^(3+)的~5D_4→~7F_5跃迁对应的余辉发光强度增大、其寿命变长。热释光谱表明ZnO含量的提高没有形成新的陷阱,而是增加了陷阶的浓度导致余辉寿命增长。光致变色实验发现:不同样品在紫外照射后其变色程度随ZnO含量增加而增加。玻璃的变色主要由色心引起,本研究中ZnO含量的增加使玻璃基质中Zn离子相关的氧空位浓度增大,从而在紫外光照射后,具有不同陷阱能级深度的色心浓度也相应增加,最终导致了所观察到的余辉特性和光致变色特性的变化结果。另外,通过对不同温度热处理后样品的透过率变化实验分析认为,陷观能级浅的色心对长余辉有贡献,能级深的将稳定存在于基质中,并对光致变色有较大贡献。

The Tb^(3+)-doped glass with different ZnO concentration of xZnO-[(100-x)/2] B_2O_3-[(100- x)/2] SiO_2(x=55, 60, 65, 70) was prepared. The allerglow and photochromism were systematically investigated by photoluminescence spectra, luminescence decay curves, thermoluminescence spectra and UV-visible absorption spectra. The intensity and time of afterglow corresponding to ~5D_4→~7F_5 transition of Tb^(3+) were found to be increased with in- creasing ZnO concentration. The thermoluminescence spectra for different samples indicate that the increase of ZnO concentration doesn't lead to the formation of new defects but addes to the concentration of original ones and results in longer time of afterglow. It is also found that the color of the glass become darker with the increasing ZnO concentration after UV-illumination irradiation through photochromism phenomena. In general, The photochromism mainly results from the color centers. In the sample with high ZnO concentration, the concentration of oxygen ion vacancy(Vo) is high, thus results in high color centers after UV-illumination, which mainly causes persistent luminescence properties and photochromism observed in the study. Furthermore, those color centers with shallow depth attribute to the long-lasting luminescence, on the other hand, those at deep depth will be stable and mainly responsible for color change.