Glasses with the base composition 16Na2O.10CaO.74SiO2 doped solely with CuO or additionally with SnO or Sb2O3 were studied by means of high temperature UV-vis-NIR spectroscopy. Increasing temperatures led to a shift of the Cu2+ absorption band from 12600cm-1 at room temperature to 11700cm-1 at 800 deg C. In glasses, doped solely with CuO, the intensity of the absorption band decreases slightly with temperature. Glasses doped with CuO and SnO showed a similar behaviour, while glasses doped with CuO and Sb2O3 showed an increase in intensity of the absorption band at temperatures >600 deg C. This was explained by the redox reaction. Decreasing temperature leads to a shift of the redox reaction to the left and hence, to a decrease in the Cu2+ concentration.
