Color Centers in X-Irradiated Soda-Silica Glasses

The coloration produced by X-irradiation in silicate glasses prepared under oxidizing and reducing conditions was studied. These glasses differed both in the position of the absorption maximums and in the thermal stability of the color centers formed. Maximums were observed at 4.10, 2.70, and 1.96 ev in oxidized glasses and at 2.15 ev in reduced glasses. Additions of a wide variety of cations to the basic glasses modified the coloration produced by X-irradiation. These modifications appeared as new centers or in the enhancement or reduction of coloration produced by X-irradiation in the base glasses. The reduction of ions such as Ce⁴⁺, Eu³⁺, and Yb³⁺ by X-irradiation is observed. Although several of the color centers appeared to be associated with the glass network itself, there was some correlation between the added cations and the coloration of the glass by X-irradiation.