Comparison of Dy3+-doped barium borate and lithium aluminoborate glass

The optical properties of Dy3+ in barium borate (BaB) glass are compared to those of Dy3+ in lithium aluminoborate (LiAlB) glass. Sample series with varying modifier-to-former ratio and different Dy3+ concentration are analyzed for their optical absorption, external quantum efficiency, luminescence yield, and chromaticity. The photoluminescence (PL) spectra are dominated by two emission bands in the visible spectral range, namely at 483 nm and 575 nm. The BaB as well as the LiAlB glass series show a luminescence quenching upon increasing the Dy3+ concentration, though the optical absorption increases linearly. For both, a change in the modifier-to former ratio from 1 : 2 to 1 : 4 leads to an increase in luminescence yield with the maximum at a Dy3+ content of (0.2-0.3) at.%. Compared to LiAlB glass, the absorption coefficient as well as the PL quantum efficiency of Dy3+ are slightly lower in BaB glass. The colour impression of the BaB and the LiAlB glass series are very similar; it changes with the modifier-to-former ratio as well as the Dy3+ concentration. The analysis of the PL lifetime measurements on the basis of the Forster model yield an intrinsic Dy3+ lifetime of slightly above 900 mu s. For a Dy3+ content of 0.5 at.%. and higher, the energy transfer between neighbouring Dy3+ ions is noticably enhanced.