Specific features of photo and thermoluminescence of Tb3+ ions in BaO-M2O3 (M=Ga, Al, In)-P2O5 glasses

BaO-P2O5 glasses mixed with the three metal oxides viz., Al2O3, Ga2O3 and In2O3 doped with Tb2O3 were prepared. The glasses were characterized by X-ray diffraction and differential thermal analysis. Optical absorption and photoluminescence spectra and thermoluminescence (TL) of these glasses have been studied. From the measured intensities of various absorption bands of these glasses, the Judd-Ofelt parameters Ω2, Ω4 and Ω6 have been evaluated and compared with those of other reported glass systems. The Judd-Ofelt theory could successfully be applied to characterize the absorption and luminescence spectra of these glasses. From this theory various radiative properties like transition probability A, branching ratio βr, the radiative lifetime τr and the emission cross-section σE for various emission levels of these glasses have been determined and reported. An attempt has also been made to throw some light on the relationship between the structural modifications and luminescence efficiencies of all the three glasses. The analysis of TL data indicate high non-radiative losses in In2O3 mixed glasses.