Optical properties of Europium doped gels during densification

Base catalyzed porous silica sol-gel monoliths fired at 1000 degrees C were used to prepare Eu and Eu-Al co-doped glasses by post doping and subsequen t densification around 1125-1150 degrees C in air. Both Eu3+ and Eu2+ ions were found to coexist in densified Al co-doped glasses. The absorption, emi ssion and excitation spectra of the Eu-doped glasses are significantly depe ndent on the alumina content. The densification temperature of the doped ge l also played a major role in the reduction process. The UV excitation effi ciency for the D-5(0) --> F-7(2) transition of Eu3+ ions (614 nm) was incre ased in the presence of Eu2+ ions due to energy transfer from Eu2+ to Eu3ions. (C) 2000 Elsevier Science B.V. All rights reserved.