Optical absorption and photoluminescence studies of Dy3+ doped alkaline earth bismuth borate glasses

Dy3+ doped alkaline earth bismuth borate glasses were prepared by the conventional melt-quenching method. The prepared glasses were characterized by absorption, excitation, emission and decay curves. Judd-Ofelt parameters were obtained from the absorption spectra recorded at 400-2000 nm. All the samples were excited at different wavelengths from UV (350 nm) to blue (450--470 nm) light and respective emission spectra are recorded. The intensity ratio of yellow to blue (Y/B) indicates that Dy3+ ions are present in low symmetry site. B2O3-Bi2O3RO (R = Ba, Sr & Ca) glasses emit efficient white light under different excitation wavelengths, which match well with the emission of commercial GaN-based blue LEDs and InGaN-based LEDs respectively. CIE coordinates were calculated from the emission spectra and found that they fall in white light region. Decay curves show single exponential nature up to 1 mol% of Dy3+ concentrations and then turn into non-exponential for 2 mol% of Dy3+ ions. Lifetime of these glasses decreases with increase of Dy3+ ion concentration.