Phase separation strategy to facilely form fluorescent [Ag2]2+/[Agm]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; [Agm]n+ quantum clusters ([Agm]n+ QCs)) in B2O3-rich and ZnO-Al2O3 rich sub-phases. The B2O3-rich sub-phase has a high solubility for Ag+ ions and [Agm]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 [Agm]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+/[Agm]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 [Agm]n+ QCs can be improved to 55.7%, and the combination of these three luminescent centers can achieve white light emission.