Structural and spectroscopic investigations on Eu3+-doped alkali fluoroborate glasses

Eu3+-doped alkali fluoroborate glasses B2O3-XCO3-NaF-Eu2O3 (where X = Li-2, Na-2, K-2, and Ca, Mg) have been prepared using the conventional melting technique and their structural and optical properties have been evaluated. The XRD pattern of the glasses confirmed the amorphous nature and the FTIR spectra reveal the presence of BO3 and BO4 units as their local structures along with the strong OH- groups. From the absorption spectra the bonding parameters have been calculated and confirmed that the Eu-O bonds in the studied glasses are of covalent nature. Judd-Ofelt (JO) analysis has been carried out from the emission spectra. The JO parameters have been used to calculate transition probabilities (A), lifetime (tau(R)) and branching ratios (beta(R)) and peak stimulated emission cross-section (sigma(E)(P)) for the D-5(0) -> F-7(J) (J=1, 2,3 and 4) transitions of the Eu3+ ions. The decay from the D-5(0) level of Eu3+ ions in the title glasses has been measured and analysed. The lifetime of the D-5(0) level is found to be shorter than the reported glasses which may be due to the presence of OH- groups. (C) 2009 Elsevier Masson SAS. All rights reserved.