Monitoring Ag nanoparticles growth in undoped and Er3+-doped glasses by in-situ UV-Vis spectroscopy and its luminescent properties

Heavy metal germanate glass compositions containing silver and erbium were prepared using the melt -quenching methodology. Ag nanoparticle formation was achieved by controlled thermal treatment and the growth was monitored by in-situ UV-Vis spectroscopy. After treatment, TEM images revealed that Ag nucleation begins after 60 min reaching an average size of 4.3 nm after 210 min. The photoluminescent properties were studied through nanoclusters Ag emission and visible upconversion of Er3+, which point out a clear dependence on the Ag nanoparticles size on the luminescent properties of the material. Furthermore, Judd-Ofelt parameters were calculated and significantly varied in respect to Ag addition and heat treatment conditions, corroborating with the proposed tunable emission, and the presence of Ag aggregates. Therefore, these results highlight the importance of the Ag nanoparticles size to control the luminescent properties of these glasses, demonstrating their potential for development of optical applications including white and green/red tunable emitting devices.