Spectroscopic and visible luminescence properties of rare earth ions in lead fluoroborate glasses

The lanthanide doped lead lithium calcium zinc fluoroborate glasses (LLCZFB:Ln) of composition 20PbF2+10Li2O+5Cao+5ZnO+59B2O3+1Ln2O3 (where Ln=Sm, Eu and Dy in mol%) were prepared by conventional melt quench technique. The amorphous nature of these glasses was confirmed by X-ray diffraction studies. The glass transition temperatures (Tg) were studied by DSC analysis. The glass structure and spectroscopic properties were investigated using optical absorption, vibrational and fluorescence spectra. The FT-IR spectra and Raman spectra reveal the presence of BO3, BO4 and non-bridging oxygen׳s. The Judd-Ofelt intensity parameters Ωλ (λ=2, 4, 6) were determined from the spectral intensities of absorption bands. These parameters were used to calculate the radiative parameters such as radiative transition probability (AR), radiative life time (τR) and branching ratio (βr) for various excited luminescent states of rare earth ions. The visible emission spectra for different rare earth ions were recorded by exciting the samples at different wavelengths and the decay rates for the different rare earth ions were measured. Using the emission spectra, full width half maxima (FWFM), stimulated emission cross section (σEp) were evaluated. The nature of decay profiles of 4F9/2, 4G5/2 and 5D0 states of Dy, Sm and Eu ions respectively are analyzed. Comparison of luminescence features of these glasses and also with those reported for different glass hosts indicates that the LLCZFB:Dy glass has strong luminescence in the visible region.