Fluorescence line narrowing and Judd-Ofelt theory analyses of Eu3+-doped low-silica calcium aluminosilicate glass and glass-ceramic

Eu-doped calcium aluminosilicate glass and glass-ceramic were synthesized and studied by site-selective spectroscopy. Using both broadband excitation and fluorescence line narrowing techniques, the D-5(0) -> F-7(1) emission transition was studied under resonant excitation at different wavelengths within the F-7(0) -> D-5(0) band. In order to explore the local structure of the systems, crystal-field analysis was applied assuming C-2v site symmetry. Moreover, from the emission spectra of glass and glass-ceramic systems, Judd-Ofelt parameters Omega(t) (t= 2, 4) were considered. Transition probability (A), stimulated emission cross-section (sigma), radiative lifetime (tau(R)) and branching ratios (beta) due to the transition D-5(0) -> F-7(J) (J = 1, 2, 3 and 4) of Eu3+ ions were evaluated in different local fields and their relative variations were discussed. The crystallization process, which converted the glass into glass-ceramic, promoted an important enhancement in the quantum efficiency, which was improved from 45% to 60%.