Visible to near-infrared down-conversion luminescence in Tb3 + and Yb3 + co-doped lithium–lanthanum–aluminosilicate oxyfluoride glass and glass-ceramics

Tb3 + and Yb3 + co-doped oxyfluoride glasses were fabricated in a lithium–lanthanum–aluminosilicate matrix (LLAS) by a melt-quench technique. Glass-ceramics were obtained by appropriate heat treatment of the as-prepared glasses. Visible to near-infrared down-conversion luminescence was studied for glass and glass-ceramic samples with different Yb3 + concentrations. It has been found that the luminescence intensity at 940–1020 nm from Yb3 + ions increases while the emission lifetime of Tb3 + ions decreases in the glass-ceramic compared to that in the as-prepared glass, which indicates that the energy transfer efficiency increases in the glass-ceramics compared to that in the as-prepared glass. The down-conversion luminescence also increased for increasing Yb3 + concentration from 1 mol% to 2 mol%, but decreased for the sample with a high Yb3 + co-doping concentration of 8 mol%, which is attributed to the concentration quenching.