Anomalous luminescence properties in Dy³⁺-doped Bi₂O₃-B₂O₃-SiO₂ glasses at high silver concentrations

Silver-containing glasses combine chemical versatility and optical functionality, making them attractive platforms for photonic applications where surface plasmon resonance (SPR) can be exploited to manipulate local electromagnetic fields. When silver species coexist with rare-earth activators, plasmonic near-fields can markedly influence excitation and radiative processes, but the outcome depends sensitively on silver speciation, size distribution, and spatial relationships to the emitters. Bi₂O₃-B₂O₃-SiO₂ glasses are particularly well suited to such studies because their high polarizability and structural tolerance allow relatively large dopant loadings while maintaining glass stability. Most prior studies have predominantly focused on the low silver doping range (<5mol%), where silver nanoparticles can serve as plasmonic sensitization centers to enhance rare-earth luminescence. However, within the high silver doping range, Ag⁰ nanoparticles, Ag⁺ ions, and sub-nanoclusters may coexist simultaneously, and their influence on optical behavior has yet to be systematically elucidated. In this study, we define "anomalous luminescence" as the non-monotonic variation in Dy³⁺ luminescence intensity and fluorescence lifetime observed in Dy³⁺-doped Bi₂O₃-B₂O₃-SiO₂ glasses with AgCl concentrations as high as 9 mol%, relative to their low-concentration behavior. We focus on investigating the aforementioned anomalous luminescence behavior of Dy³⁺ under high Ag content conditions (AgCl up to 9 mol%), along with its correlation to microstructure, chemical state, and energy transfer mechanisms. This study elucidates the competitive mechanism between plasmon-enhanced luminescence and concentration quenching.