Influence of redox synthesis conditionson the spectral and luminescent properties of germanate glass activated by bismuth ions

The spectral and luminescent properties of bismuth-containing germanate glass (0.1 and 1.0 mol % Bi 2 O 3 ) were studied as a function of redox synthesis conditions. CeO 2 and CaF 2 were introduced into the glass charge as oxidants. The temperature of glass synthesis (1500–1600°C) was a factor that stimulated the reduction processes in the melt. It was shown that the absorption coefficient of glass in the spectral visible region decreased with an increased concentration of oxidants in the charge; and the narrowing of the luminescence band in the region of 1100 nm at excitation at 532 nm was observed. Similar effects were observed at a decrease of the temperature of the glass synthesis to 1500°C. It is assumed that the optically active centers in the resulting glass are the bismuth ions in the oxidation state below 3+. The concentration of these centers in the glass can be controlled by changing the redox balance of the synthesis conditions.