Preparation and characterization of Al and B co-doped cerium containing sol-gel derived silica glasses

Glasses containing Ce were prepared by the sol-gel method at 1000 degrees C. Two parallel series of experiments, one in oxygen and other in nitrogen atmosphere, were carried out for synthesis, where parallel series of glasses were prepared with addition of boron and aluminium. The densification behaviour of the gels has been studied by physical properly measurements, as also UV-Visible-NIR and FTIR spectroscopy. The shifting of the absorption cut-off of the glasses towards shorter wavelengths with change in the atmosphere from oxygen to nitrogen and also with addition of boron or aluminium co-doping indicate that the concentration of Ce4+ ions is decreased. This is proposed to take place through electron trapping by Ce4+ (leading to formation of Ce3+) and hole trapping by non-bridging oxygens. (C) 2000 Elsevier Science B.V. All rights reserved.