Oxyhalide lead borate glasses doped with rare earth ions have been studied before and after thermal
treatment. The rare earths as optically active ions were limited to the Er3+ ions. Near-infrared
luminescence due to the main 4I13/2–4I15/2 laser transition of Er3+ was registered. The introduction
of PbX2 to the borate glass results in a reduction of spectral linewidth and an increase of luminescence lifetime of 4I13/2 state of Er3+ ions. The unusual large spectral linewidth for 4I13/2–4I15/2 transition of Er3+ in the oxide glass host was obtained, whereas the luminescence decay from 4I13/2 state is longer for a sample with PbF2 than PbCl2 and PbBr2. Heat treatment introduces transformation from a glass to transparent glass-ceramic (TGC). The coordination sphere around Er3+ ions is changed, giving important contribution to the luminescence characteristics. The spectroscopic consequence of this transformation is the increase of
luminescence lifetime and the narrowing of spectral lines of Er3+