中文摘要：

利用水热法合成了氟化物Y0.795-xGdxYb0.2Tm0.005F3（x=0.0,0.1,0.2,0.5,0.8）纳米晶。研究了退火后系列样品的上转换发光性质以及激发态辐射跃迁寿命。在980nm激发下,Y0.795-xGdxYb0.2Tm0.005F3纳米微晶样品中观察到了Tm3＋的蓝光上转换发射及紫色、紫外发射增强现象,同时还观察到Gd3＋的6D9/2、6IJ、6P5/2及6P7/2到基态8S7/2的发射。实验结果表明：样品半个波长量级的颗粒尺寸是Tm3＋紫外上转换增强以及Tm3＋到Gd3＋发生有效能量传递的重要因素。

英文摘要：

Y0.795-x GdxYb0.2 Tm0.005 F3 nanocrystals were synthesized through a hydrothermal method. After annealing in the air conditions, the upconversion （UC） emission properties under a 980 nm continuous wave semiconductor laser diode excitation were studied. The experimental results suggested that the violet and ultraviolet （UV） UC emission enhancement were observed in Y0.795-xGdxYb0.2Tm0.005F3 nanocrystals, as wall as the UC emissions from ^6D9/2, 6IJ, ^6P5/2, and ^6P7/2 states to the ground state ^8S7/2 of Gd^3＋ were shown, too. The luminescent kinetic analysis implied that, under 980 nm excitation, Yb^3＋ can transfer energy to populate the 3 P2 level of Tm^3＋ , make UV, violet, and blue UC emissions obtained, further, the ^6IJ multiplets of Gd^3＋ were populated through the energy transfer process 3 p2→^ 3 H6 （Tm^3＋ ） ：^8S7/2 →^ 6IJ （ Gd^3＋ ）. At the same time, the energy transfer processes occurred between Gd^3＋ and Yb^3＋ or Tm^3＋ based on the energy matching conditions, leading to the above mentioned UV UC emissions of Gd^3＋.