Departamento de Física, Universidad de La Laguna, 38206 La Laguna, Spain.
Phys Chem Chem Phys. 2018 Aug 15;20(32):20910-20918. doi: 10.1039/c8cp03808b.
RE-doped (Yb3+, Er3+ and Tm3+) nano-glass-ceramics (nGCs) comprising BaGdF5 nanocrystals have been developed under thermal treatment of precursor sol-gel glasses. Structural analysis by means of X-ray diffraction patterns, high-resolution transmission electron microscopy images, and energy dispersive X-ray spectroscopy measurements, confirmed the precipitation and distribution of cubic BaGdF5 nanocrystals (around 10 nm in size) in the silica glass matrix. Under near-IR excitation at 980 nm, up-conversion (UC) emissions have been studied as a function of selected dopants, the doping level and the pump power. In addition to the characteristic NIR, vis and UV UC emissions of Er3+ and Tm3+ dopant ions, the studied nGCs present intense UV UC emissions of the host fluoride nanocrystal, Gd3+. It was also observed that the relative Yb3+ content tended to improve the UC emission intensities. Corresponding UC mechanisms and energy transfer processes were analysed in terms of their energy level diagrams and confirmed by transient emission and pump power measurements. Moreover, power dependence analysis revealed that these emissions present saturation effects with the increase of Yb3+ content, even at low pump power. Results suggest that these high-efficiency UC nGCs have potential applications in UV solid state laser materials, solid state lighting and photovoltaics.
重新掺杂（Yb3+、Er3+ 和 Tm3+）纳米玻璃陶瓷（nGCs）是在热预处理先驱溶胶-凝胶玻璃的条件下制备的。通过 X 射线衍射图、高分辨率透射电子显微镜图像和能量色散 X 射线能谱测量的结构分析，证实了立方 BaGdF5 纳米晶（约 10nm 大小）在二氧化硅玻璃基质中的沉淀和分布。在 980nm 的近红外激发下，研究了上转换（UC）发射作为选定掺杂剂、掺杂水平和泵浦功率的函数。除了 Er3+和 Tm3+掺杂离子的特征近红外、可见光和紫外 UC 发射之外，研究的 nGCs 还表现出主体氟化物纳米晶 Gd3+的强烈紫外 UC 发射。还观察到相对 Yb3+含量趋于提高 UC 发射强度。根据能级图分析了相应的 UC 机制和能量转移过程，并通过瞬态发射和泵浦功率测量进行了验证。此外，功率依赖性分析表明，随着 Yb3+含量的增加，这些发射呈现出饱和效应，即使在低泵浦功率下也是如此。结果表明，这些高效 UC nGCs 在紫外固态激光材料、固态照明和光伏领域具有潜在应用。
