Structural and optical characterization of Dy-doped heavy-metal oxide and oxyhalide borate glasses.

Dy-doped borate glasses with PbO and PbX2 (X = F, Cl) were examined using Raman and luminescence spectroscopy. The Raman spectra show the structural changes of a glass network with B2O3/PbO ratios and presence of PbX2 (X = F or Cl). The photoluminescence spectra measured in the visible range present two bands located at 480 and 573 nm, which correspond to 4F9/2-6H15/2 (blue) and 4F9/2-6H13/2 (yellow) transitions of Dy3+. Luminescence decays from the 4F9/2 state and yellow/blue luminescence intensity ratios (Y/B) were analyzed as a function of glass composition (B2O3/PbO) and PbX2 (X = F, Cl) content. The branching ratios of yellow/blue luminescence increase, whereas the 4F9/2 lifetime of Dy3+ ions decreases with increasing PbO concentration. An introduction of PbX2 to the borate glass results in the increasing of 4F9/2 lifetime and decreasing of the yellow-to-blue luminescence intensity ratio. These phenomena are related to reduction of covalency between Dy3+ and O2−/X− ions. [ABSTRACT FROM AUTHOR]