Photoluminescence of silver in glassy matrices

This work studies the behavior of Ag+ ions incorporated in different silica-based glassy matrices. To this end, Ag-doped silica coatings, prepared via sol-gel and deposited on pure silica and soda-lime glasses, are investigated by means of structural and optical spectroscopy techniques. Silver tends to segregate towards the interface during the annealing process, but in the case of soda-lime glassy substrates the exchange process favors its diffusion into the substrate. The environment of Ag+ ions during the annealing process determines their final oxidation state. In the pure silica matrix, Ag+ ions are found to be unstable and tend to reduce to Ag0, with the subsequent formation of metallic nanoparticles. However, the presence of network formers and modifiers gives rise to the appearance of nonbridging oxygen, which allows the stabilization of Ag+ ions in the matrix.