Influence of the temperature on the nucleation of silver nanoparticles in Tm3+/Yb3+ codoped PbO–GeO2 glasses

The influence of the temperature on the nucleation of silver nanoparticles (NPs) in Tm3+/Yb3+ codoped PbO–GeO2 glasses was studied in this work. The infrared-to-visible frequency upconversion (UC) luminescence of Tm3+ ions was used to probe the NPs nucleation and the results were correlated with the increase of the heat-treatment temperature. Emission spectra in the blue–red region were measured by exciting the samples with a cw 980 nm diode laser in resonance with the Yb3+ transition (2F7/2 → 2F5/2). The results were correlated with transmission electron microscopy measurements and revealed the different behavior of the nucleation process as a function of temperature. The enhanced UC emission in the visible region is attributed to the increased local field in the proximity of the silver NPs combined with the Yb3+ → Tm3+ energy transfer.