Fluorescence properties of Eu3+ doped lead bearing fluoro-chloro phosphateglasses

Lead bearing glasses belonging to the family PbF2-PbCl2-P2O5 have been prep ared and their absorption edges and Urbach energies reported. The influence of composition on the ratios of red-to-orange emission intensities (R/O) o f EU3+ and yellow-to-blue emission intensities (Y/B) of Dy3+ doped in these glass systems are studied, these ratios being sensitive to covalency and s ite asymmetry effects. The local structure and multiphonon relaxation mecha nisms of Eu3+ ions are investigated by measuring the phonon side band spect ra associated with the F-7(0) --> D-5(2) transition. The phonon energies ar e correlated with vibrational modes observed in the infra-rid spectra consi dering 4-fold coordination of phosphorus ions in the present glass system. The electron-phonon coupling strengths are found to be much higher compared to other phosphate and fluoride glass matrices resulting in larger non-rad iative rates from higher energy states, D-5(f(j = 1,2,3)). The line positio ns of D-5(0) --> F-7(0) emission transition suggest 7-9 coordination of EU3 + ions with the surrounding oxygen ligand atoms. The relatively large line widths of D-5(0) --> F-7(0), emission transition show compositional influen ce of the non-bridged oxygens (NBOs) and phosphate linkages having double b onded oxygens (DBOs) coordinated to Eu3+ ions. (C) 1999 Elsevier Science B. V. All rights reserved.