Enhanced VIS and NIR emissions of Pr3+ ions in TZYN glasses containing silver ions and nanoparticles

TeO2-ZnO-YF3-NaF glasses doped with Pr2O3 and containing AgNO3 were prepared for the first time by single step melt quenching technique. Ag nanoparticles were grown by controlled heat treatment of the glasses during different periods of times (up to 10 h) at 300 °C, which is below the glass transition temperature. TEM images show the presence of Ag NPs with average diameter 10-46 nm and, in agreement, a broad absorption band, peaked around 492 nm, was observed and attributed to the surface plasmon resonance band (SPR) of the NPs in Pr3+ free glasses. UV-Vis absorption, and visible and near-infrared steady state and time-dependent fluorescence techniques were used to characterize the effect of the NPs on the emission properties of Pr3+. The enhancement of Pr3+ Stokes luminescence with the increase in NPs concentration was observed for samples excited in resonance (480 nm) and off-resonance (440 and 470 nm) with the SPR band. An increase of the excited state lifetime value for Pr3+:3P0 level was also observed in the presence of other Ag species (dimmers, trimmers, molecule-like and non plasmonic Ag particles) and NPs. Thus, the results show that besides the possible local field effect of the NPs, the enhancement of luminescence intensity is also likely to be due to energy transfer from the Ag species to Pr3+ ions. These new glasses show interesting properties that could become useful for photonic device applications.