Gd^(3+)掺杂增强Ho^(3+)/Yb^(3+)/Y_2O_3纳米晶绿色上转换荧光发射的研究

Enhanced Green Upconversion Emissions in Ho^(3+)/Yb^(3+) Codoped Y_2O_3 Nanocrystals with Gd^(3+) Ions

通过溶胶凝胶法制备了Gd^(3+)、Ho^(3+)和Yb^(3+)共掺的Y_2O_3纳米晶.随着Gd^(3+)掺杂浓度从0 mol%增加到20 mol%,Ho^(3+)的绿色上转换荧光发射强度明显增强,红色上转换荧光发射强度几乎没有发生变化.当掺杂20 mol%Gd^(3+)时,Ho^(3+)的绿色和红色上转换荧光的抑制比增大到了没掺杂Gd^(3+)时的3倍.透射电镜(TEM)实验表明,绿色上转换荧光强度的增强不是由于晶粒尺寸改变引起的.理论研究和时间寿命实验表明绿色上转换荧光强度的增强来自于Ho^(3+)的5I6能级和Yb^(3+)的2F5/2能级寿命的增加.

The Gd3 ＋ , Ho3＋ and Yb3＋ ions doped Y2O3 nanocrystals were prepared by sol -gel method. The green UC emission intensity was obviously enhanced along with an increase in the relative content of Gd3 ＋ ions from 0 to 20 mol%. However, the red UC emission intensity was barely enhanced. The green - to -red intensity ratio of Y1.43sGd0.4Yb0.16Ho0.002O3 nanocrystal was three times higher than that of Y1.838Yb0. 16 Ho0.00203 nanocrystal. TEM confirmed that the enhancement is not from the change of the crystal size. Theoretical calculations and decay time investigations illustrated that the enhancement in the green UC emission resulted from the induction of the Gd3＋ , which increased the lifetimes in the intermediate 2F5/2 （Yb） and 5I6 （Ho） states.