Long- and Short- Range Order in Silicate Glasses Following Silver Ion Exchange

Infrared reflectance spectra have been shown to be sensitive to the intermediate-range order (IRO, 2-5 nm) and short-range order (SRO, 1-2 nm) of silica and silicates due to changes in fictive temperature and the diffusion of ions like Ag into the silica matrix. As the diffusion of metal ions in silica is affected by the IRO and SRO, knowledge of the structure changes induced provides us with how the metal ions can be expected to nucleate and grow into metal nanoparticles (MNPs) with thermal or laser annealing. Understanding this process may provide pathways to control the formation and growth of the MNPs, their location in the substrate, and their optical properties. Because of the very small scale of the SRO and IRO, these changes in the SRO-IRO order are difficult to measure except by the changes it brings to the more global matrix responses such as to the infrared and Raman spectra of the silica matrix. Using FTIR and optical measurements, we show that silicates can behave like an effective sponge, keeping their structure while loading the matrix with metal nanoparticles of Ag using the ion exchange process