Spectroscopic features of Pr3+, Nd3+, Sm3+ and Er3+ ions in Li2O-MO (Nb2O5, MoO3 and WO3)-B2O3 glass systems

Li2O-MO (Nb2O5, MoO3 and WO3)-B2O3 glasses doped with four rare earth ions, viz., Pr3+, Nd3+, Sm3+ and Er3+ (of 1.0 mol% each) were prepared. The glasses were characterized by X-ray diffraction, differential scanning calorimetry, ESR, optical absorption and photoluminescence spectra. From the measured intensities of various absorption bands of these glasses, the Judd-Ofelt parameters Ω2, Ω4 and Ω6 have been evaluated. 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 life time 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 the data indicated high non-radiative losses in Nb2O5 mixed glasses.