The role of ligand coordination on the spectral features of Yb3+ ions in lead aluminum silicate glasses

The glasses of the composition (40 − x)PbO–(5 + x)Al2O3–54SiO2:1.0Yb2O3 (in mol%) with x ranging from 5 to 10 have been synthesized. The IR spectral studies of these glasses have indicated that there is a gradual transformation of Al3+ ions from tetrahedral to octahedral coordination with increase of Al2O3 content in the glass network. The optical absorption and luminescence spectra have exhibited bands originating from 2F7/2 → 2F5/2 and 2F5/2 → 2F7/2 transitions, respectively. From these spectra, the absorption and emission cross-sections and fluorescence lifetime of Yb3+ ions have been evaluated. Quantitative analysis of these data indicated a decreasing radiative trapping and increasing fluorescence lifetime of Yb3+ ions with increasing Al2O3 content. This may be explained by structural variations in the vicinity of Yb3+ ions due to variation in the concentration of Al2O3 in the glass network.