ELECTRON-IRRADIATION DAMAGE IN QUARTZ

Electron irradiation damage in quartz has been studied by transmission electron microscopy as a function of accelerating voltage from 50-650 kV at room temperature. Black spot damage was observed at all voltages, the damage rate being faster at higher accelerating voltages. In the voltage range 50-100 kV, black spots grew in size with time until they became resolvable as dislocation loops. Additional irradiation at all voltages gradually induced a crystalline-to-amorphous transition when the irradiated area became featureless and the crystalline diffraction pattern was replaced by amorphous rings. It was observed that the dose required for the transformation increased approximately linearly with increasing accelerating voltage. These results are discussed in terms of displacement damage and ionization damage processes.