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

摘要

Dy-doped borate glasses with PbO and PbX_2 (X = F, Cl) were examined using Raman and luminescence spectroscopy. The Raman spectra show the structural changes of a glass network with B_2O_3/PbO ratios and presence of PbX_2 (X = F or Cl). The photoluminescence spectra measured in the visible range present two bands located at 480 and 573 nm, which correspond to ~4F_(9/2-)~6H_(15/2) (blue) and ~4F_(9/2-)-~6H_(13/2) (yellow) transitions of Dy~(3+). Luminescence decays from the~ 4F_(9/2) state and yellow/ blue luminescence intensity ratios (Y/B) were analyzed as a function of glass composition (B_2O_3/PbO) and PbX_2 (X = F, Cl) content. The branching ratios of yellow/blue luminescence increase, whereas the ~4F_(9/2) lifetime of Dy~(3+) ions decreases with increasing PbO concentration. An introduction of PbX_2 to the borate glass results in the increasing of ~4F_(9/2) lifetime and decreasing of the yellow-to-blue luminescence intensity ratio. These phenomena are related to reduction of covalency between Dy~(3+) and O~(2-)/X~- ions.