Effects of Heat Treatment and Yb 3+ Concentration on the Downconversion Emission of Er 3+ /Yb 3+ Co-Doped Transparent Silicate Glass-Ceramics

The SiO2-Al2O3-BaF2-TiO2-CaF2 transparent silicate glass-ceramics containing BaF2 nanocrystals were successfully prepared by heat treatment process through conventional melting method. Effects of heat treatment processes and Yb3+ concentration on the downconversion (DC) emission of the co-doped Er3+/Yb3+ transparent silicate glass-ceramics were investigated. With the increase of temperatures and times of heat treatment process, the DC emission intensity of the co-doped Er3+/Yb3+ glass-ceramics was significantly enhanced. At the same time, with the increase of Yb3+ concentration, the value of DC intensity of Er3+/Yb3+ co-doped bands centered at 849, 883 and 1533 nm is maximized when the concentration of Yb3+ reaches 2.5 mol.%. When the concentration exceed 2.5 mol. %, the DC emission intensity of Er3+/Yb3+ co-doped bands centered at 849, 883 and 1533 nm was decreased, owing to the self-quenching effect. It’s interesting that the DC emission intensity of Er3+/Yb3+ co-doped band centered at 978 nm didn’t quench when the Yb3+ concentration exceed 2.5 mol. %. At the same time, the DC mechanism and ET processes between Yb3+ and Er3+ ions were discussed.

采用传统熔融法结合热处理工艺，成功制备出含有BaF₂纳米晶的SiO₂-Al₂O₃-BaF₂-TiO₂-CaF₂系透明硅酸盐微晶玻璃。研究了热处理工艺与Yb³+掺杂浓度对共掺Er³+/Yb³+透明硅酸盐微晶玻璃下转换（downconversion, DC）发光性能的影响。结果表明，随着热处理温度升高与保温时间延长，共掺Er³+/Yb³+微晶玻璃的下转换发光强度显著提升。同时，随着Yb³+掺杂浓度升高，中心位于849 nm、883 nm与1533 nm处的Er³+/Yb³+共掺杂发光波段的下转换强度先增后降，在Yb³+掺杂浓度为2.5 mol.%时达到峰值；当Yb³+掺杂浓度超过2.5 mol.%时，上述波段的下转换发光强度因自猝灭效应出现下降。值得注意的是，中心位于978 nm处的Er³+/Yb³+共掺杂发光波段的下转换发光强度，在Yb³+掺杂浓度超过2.5 mol.%时并未发生猝灭。此外，本文还探讨了Yb³+与Er³+离子间的下转换发光机制与能量传递（energy transfer, ET）过程。