Influence of Al declustering on the photoluminescent properties of Pr3+ ions in PbO-SiO2 glasses

Pr3+ doped lead alumino silicate glasses with varying concentrations of Al2O3 (from 5 to 10 mol%) have been synthesized. The IR and Raman spectral studies of these glasses have indicated that there is a gradual increase in the depolymerization of the glass network with an increase in the concentration of Al2O3. The optical absorption, luminescence spectra and fluorescence decay curves of these glasses were recorded at room temperature. 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. From these spectra, the radiative parameters viz., spontaneous emission probability A, the total emission probability A(T), the radiative lifetime T, the fluorescent branching ratio p of different transitions that originated from the P-3(0) level of Pr3+ ions have been evaluated. A considerable enhancement in the luminescence emission, especially in the red region corresponding to P-3(0)-> H-3(6), F-3(2) transitions has been observed. The increase has been attributed to the possible admixing of wavefunctions of opposite parities and due to the declusterization of Pr3+ ions by Al3+ ions in the glass network. The branching ratio beta has been observed to be the highest for the transition P-3(0)-> F-3(2) and it is found to be similar to 50% for the glass mixed with 10 mol% of Al2O3. The CIE color coordinates for three glasses have been evaluated and found to be in the bright red region. (C) 2012 Elsevier B.V. All rights reserved.