Dimensional changes of silica-, borosilicate- and germania-glasses and quartz under irradiation

Length changes of crystalline SiO2, of two SiO2 glasses (HERASIL1, SUPRASIL1), of two SiO2–B2O3 glasses (DURAN, VYCOR) and of vitreous GeO2 were measured during proton, electron and UV irradiations under various applied tensile stresses at temperatures up to 400 °C. No change was observed under UV irradiation, while proton and electron irradiation initially caused transient compaction and subsequent irradiation induced creep with linear stress dependence (viscous flow). Asymptotic compaction strain is reduced at elevated temperatures due to recovery processes, while creep rate is virtually independent of temperature. Compaction tends to decrease while creep rate increases with decreasing SiO2 content of the glasses. A comparison of flow rates to electronic and nuclear stopping power gives no safe discrimination of the underlying mechanisms. Quartz shows continuous dilatation under proton irradiation, with a very low stress dependence, which allows only determination of an upper limit of viscous flow compliance.