摘要
Er^3- / Yb^3＋ co - doped silica - alumina monolithic xerogels were prepared with the same concentration on 2 000 Er/Si ppm and 6 000 AI/Si ppm. The Yb/Si content was varied from 0 to 4 000 ppm. Densification of the samples was achieved by thermal treatment in air at 950 ~C for 120 hours with a heating rate 0.1 ~C / min. Photoluminescence spectroscopy was used to obtain information about the effective excitation efficiency of Er^3＋ ions by co-doping with Yb^3- ions. The infrared-to-visible up-conversion luminescence has been investigated upon continuous wave excitation at 980 nm. The samples exhibit red, green and blue upconversion emission. It is found that the intensity of up-conversion luminescence increases with increasing Yb3- doping concentration. An opposite behavior is observed for the 4 I13/2 luminescence of the Er^3＋ ions.
基金
This research is performed in the context of the Italy-Vietnamre-search project 6 BS 2 MAE2006-2008 .MIUR-FIRB RBNE012N3X,PAT FAPVU2004-2006 ,MIUR-PRIN2004-2006 .
