Structural and luminescence behaviour of Er3+ doped telluro-fluoroborate glasses

The Er3+ doped telluro-fluoroborate glasses with the chemical composition (30 - x)B2O3 + 30TeO(2) + 16ZnO + 10ZnF(2) + 7CaF(2) + 7BaF(2) + xEr(2)O(3) (x = 0.05, 0.1, 0.5, 0.75, 1.0 and 3 in wt%) have been prepared by melt quenching technique and characterized through XRD, SEM, FTIR, Raman, absorption and luminescence spectral analysis. The XRD and SEM measurements were made to examine the amorphous nature. The presence of various stretching and bending vibration modes of functional groups have been investigated through FTIR and Raman spectra. The bonding parameters ((beta) over bar and delta) were calculated from the absorption spectra to claim the covalent/ionic nature of the metal-ligand bond in the prepared glasses. From the absorption spectra, optical band gap energies (E-opt) corresponding to the direct and indirect allowed transitions were calculated to analyze the electronic band structure. The Urbach energy values have also been estimated and discussed. The Judd-Ofelt (JO) intensity parameters (Omega(lambda) (lambda = 2, 4, 6)) were determined from the absorption spectra in order to study the symmetry around the RE ion site and used to compute the radiative properties such as transition probability (A(R)), stimulated emission cross-section (sigma(E)(P)) and branching ratios (beta(R)) for the different emission transitions. The emission intensities of the prepared glasses were characterized through CIE 1931 chromaticity diagram and the results were discussed and compared with the reported literature. (C) 2014 Elsevier B.V. All rights reserved.