State Key Laboratory of Luminescent Materials and Devices, and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510640, China.
Nanoscale. 2012 Aug 7;4(15):4658-66. doi: 10.1039/c2nr30998j. Epub 2012 Jun 25.
The morphology, size and phase control of luminescent fluoride nanocrystals through doping has become a new research hotspot due to their improved properties. In this work, Yb(3+) ions, as one of the most efficient sensitizers for various lanthanide activators, were doped in NaGd(Y)F(4) nanocrystals. The results show that no obvious influence was observed for Yb(3+)-doped NaYF(4) nanocrystals, while the influence of Yb(3+) doping on NaGdF(4) nanocrystals was remarkable. The NaGd(1-x)Yb(x)F(4) nanocrystals were synthesized by a hydrothermal route and had a morphology of rice-like nanorods. By controlling the synthesis parameters, the average size and slenderness of the nanocrystals increased gradually with addition of Yb(3+) ions. In contrast, the NaGd(1-x)Yb(x)F(4) nanocrystals maintained a hexagonal phase, which is more beneficial for application as a luminescent host, until the content of Yb(3+) ions reached x = 0.9. The growth and transformation mechanism of NaGd(1-x)Yb(x)F(4) nanocrystals was proposed to be a result of the competition between ion diffusion and an Oswald ripening process. Photoluminescence (PL) spectra confirm the efficient up-conversion and near-infrared (NIR) two-model luminescence properties of Er(3+) (Tm(3+)) activated NaGd(Y)(1-x)Yb(x)F(4) nanocrystals. Simulated analysis results indicate that a colloidal solution of mixed luminescent nanocrystals is expected to find application as the activated medium of three dimensional displays and a broadband optical amplifier.
通过掺杂来控制发光氟化物纳米晶体的形态、尺寸和相结构已成为一个新的研究热点，因为这可以改善其性能。在这项工作中，Yb3+离子作为各种镧系元素激活剂最有效的敏化剂之一，被掺杂到 NaGd(Y)F4纳米晶体中。结果表明，Yb3+掺杂对 NaYF4纳米晶体没有明显的影响，而对 NaGdF4纳米晶体的影响则很显著。通过水热法合成了 NaGd1-xYbxF4纳米晶体，其形貌为稻穗状纳米棒。通过控制合成参数，纳米晶体的平均尺寸和长径比随着 Yb3+离子的加入逐渐增大。相比之下，NaGd1-xYbxF4纳米晶体保持了六方相，这更有利于作为发光基质，直到 Yb3+离子的含量达到 x = 0.9。提出了 NaGd1-xYbxF4纳米晶体的生长和转化机制，这是离子扩散和奥斯特熟化过程竞争的结果。光致发光（PL）光谱证实了 Er3+（Tm3+）激活的 NaGd(Y)(1-x)YbxF4纳米晶体具有高效的上转换和近红外（NIR）双模态发光性能。模拟分析结果表明，混合发光纳米晶体的胶体溶液有望作为三维显示的激活介质和宽带光放大器得到应用。
