Studies on optimizing sesquioxide contents to enhance luminescence efficiency of Pr3+ ions in PbO-PbF2-B2O3 glass system

Pr3+ doped lead oxy fluoro borate glasses mixed with three sesquioxides (M2O3) viz. Y2O3, Sc2O3, Al2O3 of different concentrations (0-10 mol%) have been synthesized. The preliminary understanding over the structural modifications due to the insertion of the sesquioxides in the glass network could be obtained by IR spectral investigations. The optical absorption, luminescence spectra and fluorescence decay curves of these glasses were studied as functions of concentration of M2O3. The luminescence spectra of these glasses have exhibited the bands due to P-3(0) -> F-3(2), F-3(3), H-3(6), H-3(4), H-3(5) transitions of Pr3+ ions. From these spectra, the radiative parameters viz., spontaneous emission probability A, the total emission probability A(T), the radiative lifetime tau, the fluorescent branching ratio beta of different transitions originated from P-3(0) level of Pr3+ ions have been evaluated. A considerable enhancement in the luminescence emission corresponding to P-3(0) -> H-3(6), F-3(2) transitions has been observed with increase in the concentraion of M2O3 up to 8.0 mol%. The increase has been attributed to the possible declusterization of Pr3+ ions by M3+ ions in the glass network. The comparison of emissive characteristics of the glasses mixed with three sesquioxides indicated the highest luminescence efficiency for Y2O3 mixed glasses among the three series glasses studied and this has been explained in terms of different degrees of variations in the structural modifications in the vicinity of Pr3+ ion in the glass network. (C) 2014 Elsevier B.V. All rights reserved.