Structural and luminescence behavior of Er3+ ions doped Barium tellurofluoroborate glasses

Er3+ doped Barium tellurofluoroborate glasses (BTFBxE) with the chemical composition (30 - x)TeO2 + 30B(2)O(3) + 20BaO + 20BaF + xEr(2)O(3) (where x = 0.01, 0.05, 0.1, 0.5, 1.0 and 2.0 in wt%) were prepared following the melt quenching technique. The different vibrational modes of borates and tellurites in the prepared glasses were explored through FTIR and Raman spectra. The optical absorption spectra have been used to determine the ionic/covalent nature of the metal ligand bond in the prepared glasses with the help of Nephelauxetic ratio (beta) and bonding parameter (delta) studies. The optical band gap of direct and indirect allowed transitions were determined from Tauc's plot and the variations of band gap energy with structural arrangements were discussed. The Urbach energy values were determined and the relatively lower values of the Urbach's energy reveal the minimal degree of disordemess in the prepared glasses. The oscillator strengths (f(exp) and f(cal)) and Judd-Ofelt (JO) intensity parameters (Omega(2), Omega(4) and Omega(6)) were calculated with the application of JO theory and the trends of the JO intensity parameters are found to be Omega(2) > Omega(6) > Omega(4) for all the prepared glasses with a minimum variation in 02 intensity parameter values. A bright green emission was observed from the H-2(11/2) + S-4(3/2) -> I-4(15/2) transition and the radiative properties such as transition probability (A), stimulated emission cross-section (sigma(E)(P),), branching ratio (beta(r)) and radiative lifetime (tau) were calculated using the JO parameters. The suitability of the prepared glasses for the fabrication of photonic devices were also discussed and reported in the present work. (C) 2014 Elsevier B.V. All rights reserved.