Effect of annealing on fluorescence of Ce3+-doped silica prepared by sol-gel process

We prepared Ce3+-doped silica by the sol-gel method and studied the effect of annealing on fluorescence of these samples. Different fluorescence was o bserved for samples annealed at different temperatures, changing gradually from solution like fluorescence to fluorescence similar to that observed in the Ce3+-doped silica prepared by chemical vapor deposition. It was found that the emission intensity first decreased with increasing annealing tempe rature until 500 degreesC, and then increased with the temperature ranging from 500 to 950 degreesC. Meanwhile, the emission peak showed a large red s hift and an obvious broadening. These changes were attributed to the anneal ing-induced structural evolution in silica: Ce3+ ions changed from coordina ting with water and terminal OH-groups to embedding in silica network.