Stress Build-up in Binary Borate Glasses by Ultra-violet Irradiation Stress in Glass Caused by Ultra-violet Irradiation (Part 6)

Abstract

As the first step to determine the kinds or the compositions of glasses that show the stress build up caused by ultra-violet irradiation, binary borate glasses containing respectively oxides of Li, Na, K, Ca, Sr, Ba, Cd, La, Bi, Pb, Tl, Si, and Zn, were prepared and subjected to ultra-violet irradiation. The irradiated surface layers of the glasses were examined photoelastically. Stress build-up was observed only in the glasses containing Li₂O, Na₂O and K₂O. Possible mechanisms of the stress build-up and the behaviour of alkali ions or change of coordination number of B³⁺ ions were discussed.
With alkali germanate glasses, although change of coordination number of Ge⁴⁺ ions seems possible with change of glass composition, stress buildup was not found by ultra-violet irradiation.