Phase separation strategy to facilely form fluorescent [Ag₂]²⁺/[Ag_m]ⁿ⁺ quantum clusters in boro-alumino-silicate multiphase glasses

Abstract

By adjusting the content of ZnF₂-SrF₂/ZnO-SrO, a series of SiO₂-Al₂O₃-B₂O₃-Na₂O-ZnO/ZnF₂-SrO/SrF₂-Ag multiphase glasses was designed and prepared via a melt-quenching method. Under a phase separation strategy, negatively charged tetrahedrons ([BO₄]^-, [ZnO₄]^2-, and [AlO₄]^-) can be generated to stabilize different silver species (Ag⁺ ions; [Ag₂]²⁺ pairs; [Ag_m]ⁿ⁺ quantum clusters ([Ag_m]ⁿ⁺ QCs)) in B₂O₃-rich and ZnO-Al₂O₃ rich sub-phases. The B₂O₃-rich sub-phase has a high solubility for Ag⁺ ions and [Ag_m]ⁿ⁺ QCs. The fluoride-rich phase shows a good ability to extract Na⁺ from the B₂O₃-rich sub-phase, significantly affects the solubility of Ag⁺ in the B₂O₃-rich sub-phase, and eventually determines the aggregation from Ag⁺ ions and Ag⁰ atom to [Ag_m]ⁿ⁺ QCs. The ZnO-Al₂O₃-rich or ZnO-SiO₂-rich (i.e. SiO₂-rich in GZnOSrO) phase has a relatively high solubility for [Ag₂]²⁺ pairs. The Ag⁺/[Ag₂]²⁺/[Ag_m]ⁿ⁺ QC fluorescent centers were identified by spectroscopic analysis, where the fluorescence bands are located in the ultraviolet, green-white and orange spectral regions, respectively. The fluorescent quantum yield (QY) of the [Ag_m]ⁿ⁺ QCs can be improved to 55.7%, and the combination of these three luminescent centers can achieve white light emission.