Influence of Mn2+ sensitizers on orange-red emission of Pr3+ ions in BaO-Al2O3-B2O3-SiO2 glass system

Emission characteristics of Pr3+ ions sensitized with different concentrations Mn2+ ions in BaO-Al2O3-B2O3-SiO2 (BaA1BS) glass host were investigated. To have some pre-understanding over the structural modifications taking place in the glass network (which may help in understanding the variations the PL emission) due to the variation in the concentration of MnO, the spectroscopic studies like IR, EPR were also undertaken. The analysis of the results of IR spectral studies have indicated a gradual increase in the degree of depolymerisation of the glass network with increase in the concentration of MnO, whereas the EPR spectral studies have revealed a gradual increase in the concentration of octahedral positions of Mn2+ ions in the glass network. The luminescence emission spectrum of Pr3+ ions (individually) doped glass when excited at 476 nm exhibited conventional emission bands due to P-3(o)-> H-3(4), H-3(3),H-3(6); P-3(1)-> H-3(3),F-3(3) and D-1(2)-> H-3(4) transitions in the visible region. The emission spectrum of Mn2+ ions (individually) doped glasses when excited at the same wavelength also exhibited a distinct emission band at about 600 nm identified as being due to T-4(1g) ->(6)A(1g) octahedral transition s of Mn2+ ions. When the Pr3+ ions are codoped with Mn2+ ions, a substantial hike in the orange emission band of Pr3+ ions could be visualized. When the glasses are co-doped with 1.0 mol% of MnO, nearly 4 fold increase in the intensity of P-3(o)-> H-3(6) (orange emission band) is observed. The increase is attributed to the transfer of energy from T-4(1g)->(6)A(1g) emission transition of Mn2+ ions to P-3(o)-> H-3(6) emission transition of Pr3+ ions. The results were further quantitatively analyzed using IR and EPR spectral studies and finally concluded that Mn2+ ions are efficient sensitizers in improving the orange red emission of Pr(3+)ions in the titled glass host.