Luminescence of oxyfluoride glasses co-doped with Ag nanoclusters and Yb³⁺ ions

Bulk oxyfluoride glasses co-doped with Ag nanoclusters and Yb³⁺ ions have been prepared by a melt quenching technique. When excited in the absorption band of the Ag nanoclusters between 300 to 500 nm, these glasses emit a broad band characteristic of the Ag nanoclusters between 400 to 750 nm as well as an emission band between 900 to 1100 nm, originating from Yb³⁺ ions. The intensity ratio of the Yb³⁺/Ag emission bands increases with the Ag doping level at a fixed concentration of Yb³⁺, indicating the presence of energy transfer mechanism from the Ag nanoclusters to the Yb³⁺ ions. Comparison of time-resolved decay kinetics of the luminescence in the respectively Ag nanocluster-Yb³⁺ co-doped and single Ag nanocluster doped glasses, hints towards an energy transfer from the red and infrared emitting Ag nanoclusters to the Yb³⁺ ions.