Influence of modifier oxides on spectroscopic properties of Sm3+ doped lithium fluoroborate glass

Sm3+ doped lithium fluoro-borate glasses with different modifier oxides (Li2B4O7–BaF2–NaF–MO where M = Mg, Ca, Cd and Pb) and combinations of modifier oxides (Li2B4O7–BaF2–NaF–MgO+CaO, Li2B4O7–BaF2–NaF–CdO+PbO) were prepared by means of melt quenching method. These samples were characterized by XRD, FTIR, optical absorption and fluorescence techniques at room temperature. The XRD profiles of all the glasses confirm their amorphous nature and the FTIR spectra reveal the presence of BO3 and BO4 units along with the strong OH− groups in the glass matrices. The influence of modifier oxides on Judd–Ofelt (J–O) intensity parameters and intensity of the emission lines are reported. Judd–Ofelt theory is used to study the spectral properties and to calculate the radiative transition probabilities (AT), branching ratios (βR), integrated absorption cross sections (Σ) and radiative lifetimes (τR) for certain spectral transitions. From the emission spectral analysis, emission cross-sections (σP) are calculated for the four emission transitions, 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and 4G5/2 → 6H11/2 of Sm3+ ion in different lithium fluoro-borate glasses. Among the four transitions, it is observed that the transition 4G5/2 → 6H7/2 has higher emission cross-section (σP) in all the glass matrices, except in Mg, Cd and Mg–Ca glass matrices. The non-exponential nature of the luminescence decay curves of 4G5/2 level of Sm3+ doped glass matrices are also reported.