Li Ji-Guang, Wang Xuejiao, Liu Weigang, Zhu Qi, Li Xiaodong, Sun Xudong
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning, 110819, China.
Institute of Ceramics and Powder Metallurgy, School of Materials Science and Engineering, Northeastern University, Shenyang, Liaoning, 110819, China.
Nanoscale Res Lett. 2017 Aug 24;12(1):508. doi: 10.1186/s11671-017-2277-4.
Phase-pure (LaREYb)OS upconversion (UC) nanophosphors (average crystallite size ~ 45 nm; RE=Ho, Er) were annealed from their hydrothermally crystallized layered hydroxyl sulfate precursors in flowing hydrogen at 1200 °C for 1 h, with water vapor as the only exhaust. Under 978-nm laser excitation (up to 2.0 W), the Ho-doped phosphor exhibited green (medium), red (weak), and near-infrared (strong) emissions at ~ 546 (F → I), 658 (F → I), and 763 nm (F → I), respectively, and has the stable chromaticity coordinates of about (0.30, 0.66) in the visible-light region (400-700 nm). The Er-doped UC phosphor, on the other hand, showed weak green (~ 527/549 nm, H,S → I), weak red (668/672 nm, F → I), and strong near-infrared ( 807/58 nm, I → I) luminescence, whose emission color in the visible region drifted from yellowish-green [(0.36, 0.61)] to green [(0.32, 0.64)] with increasing excitation power. Analysis of the power-dependent UC luminescence found three- and two-photon processes for RE=Ho and Er, respectively, and the possible UC mechanisms were proposed.
纯相（LaREYb）OS上转换（UC）纳米磷光体（平均微晶尺寸约45纳米；RE = Ho、Er）由其水热结晶的层状羟基硫酸盐前驱体在1200℃的流动氢气中退火1小时，唯一的废气是水蒸气。在978纳米激光激发（高达2.0瓦）下，掺Ho磷光体分别在约546（F→I）、658（F→I）和763纳米（F→I）处表现出绿色（中等）、红色（弱）和近红外（强）发射，并且在可见光区域（400 - 700纳米）具有约（0.30，0.66）的稳定色度坐标。另一方面，掺Er的UC磷光体表现出弱绿色（约527/549纳米，H，S→I）、弱红色（约668/672纳米，F→I）和强近红外（约807/58纳米，I→I）发光，其在可见光区域的发射颜色随着激发功率的增加从黄绿色[(0.36, 0.61)]漂移到绿色[(0.32, 0.64)]。对功率依赖的UC发光分析发现，对于RE = Ho和Er分别存在三光子和双光子过程，并提出了可能的UC机制。
