5D3→7FJ emission in terbium-doped sol–gel glasses

In silicate sol–gel glass doped with trivalent terbium, the intensity of violet and blue fluorescence from the 5D3 level is highly dependent on terbium concentration, on the presence of Al3+ co-dopant, and on annealing conditions. Evidence is presented that aluminum co-doping prevents rare earth clusters from forming, and also modifies the coupling of rare earth ions to the local environment. 5D3 emission is observed in glasses annealed at 750 °C, and increases in intensity with increasing annealing time and with higher temperature. This behavior is shown to be due to the removal of residual hydroxyl ions.