Optical properties of transition-metal ions in zirconium-based metal fluoride glasses andMgF2crystals

The optical properties of the transition-metal ions, ${\mathrm{Ni}}^{2+}$, ${\mathrm{Co}}^{2+}$, and ${\mathrm{Mn}}^{2+}$, in zirconium-barium-lanthanum-aluminum (ZBLA) fluoride glass are reported. Comparisons of the absorption spectra, luminescence spectra, and luminescence lifetimes for these ions in ZBLA and in ${\mathrm{MgF}}_2$ crystals have yielded the following results. The crystal field in the glass is much reduced compared with that in ${\mathrm{MgF}}_2$. The oscillator strengths of the optical transitions for the ions in the glass hosts are almost an order of magnitude larger than similar transitions in ${\mathrm{MgF}}_2$ crystals, but nonradiative transitions are apparently much more pronounced in the glass. This results in luminescence quenching at lower temperatures in the glass.