Influence of Ag nanoparticles on luminescent performance of SiO2:Tb3 + nanomaterials

Tb^3 + single-doped SiO₂ (SiO₂:Tb^3 +) and Tb^3 +, Ag co-doped SiO₂ (SiO₂:Tb^3 +–Ag) nanostructured luminescent materials were prepared by a modified Stöber method. Their microstructure and optical property were investigated using scanning electron microscopy, ultraviolet visible absorption and photoluminescence spectrophotometry. Results show that the samples are composed of well-dispersed near-spherical particles with a diameter about 50 nm, the highest fluorescence intensity is obtained when the doping concentration of Tb^3 + is 4.86 mol%, the corresponding internal quantum efficiency is 13.6% and the external quantum efficiency is 8.2%. The experimental results indicate that Ag nanoparticles can greatly enhance the light absorption at 226 nm and the light emission at 543 nm of SiO₂:Tb^3 +–Ag, and the fluorescence lifetime reduces with increasing Ag concentration in SiO₂:Tb^3 +–Ag. Additionally, the present results indicate that fluorescence enhancement is attributed to the local field enhancement and the increased radiative decay rates induced by Ag nanoparticles.