Effect of Yb3+ concentration on Er3+ luminescence properties of sol-gelderived silica-alumina xerogels

Abstract:

Er³⁺ / Yb³⁺ co-doped silica-alumina monolithic xerogels were prepared with the same concentration on 2 000 Er/Si ppm and 6 000 Al/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 Er³⁺ ions by co-doping with Yb³⁺ 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 up-conversion emission. It is found that the intensity of up-conversion luminescence increases with increasing Yb³⁺ doping concentration. An opposite behavior is observed for the⁴l_13/2 luminescence of the Er³⁺ ions. This research is performed in the context of the Italy-Vietnam research project 6 BS 2 MAE 2006–2008. MIUR-FIRB RBNE012 N3X, PAT FAPVU2004–2006, MIUR-PRIN 2004–2006.