Gamma‐Ray Induced Coloring of Some Phosphate Glasses

The changes in gamma‐ray induced optical absorption in phosphate glasses resulting from changes in composition, conditions during melting, and additions of small amounts of some oxides are discussed. A resolution of the induced spectra showed that the observed absorption is due to the superposition of three bands at 2.3, 2.9, and 5.5 e.v. (540, 425, and 225 mü) and to a fourth band whose absorption peak is beyond 6 e.v. The ultraviolet induced absorption increases, whereas the visible absorption decreases in glasses melted under reducing conditions as opposed to those melted under normal conditions in air and on replacement of K + by Na + or Li + . A similar effect is produced on replacement of Ba ++ by Pb++ and on the addition of T1 2 O to a CaO‐P 2 O 5 glass or the addition of As 2 O 3 to a CaOP 2 O 5 , GeO 2 glass. Additions of large amounts of GeO 2 are accompanied by a decrease in the number of nonbridging oxygens and a decrease in the visible induced absorption. Replacement of Ca ++ by Ba ++ ions showed an over‐all decrease in the induced absorption. The addition of small amounts of the oxides of germanium, titanium, iron, thallium, niobium, and arsenic showed an appreciable effect in inhibiting the visible induced coloration.