Electron irradiation damage effects in hydrothermal grown quartz crystals

Abstract

Electron irradiation effects in synthetic quartz single crystals were investigated to determine the extent of damage of the crystals during transmission electron microscopy examination, as the rapid deterioration is of major concern. On exposure of the quartz crystals to electron flux of 3.0 x 108 e/cm2/s at 200 kV accelerating voltage, irradiation damage in the form of black beam spots, defect clusters, prismatic dislocation loops, and long segments of dislocation appeared. The microstructure indicated that during irradiation, the primary defects in quartz attained sufficiently high mobility, thereby permitting large-scale recombination and clustering leading to rapid creation of secondary defects. The rate of damage was dependent on the annealing temperature, initial defect density and hydroxyl (OH) content. Channeling effect in the open structures of quartz lattice enhanced electron collision leading to very long defect trajectories. The number of electrons lost by the recombination process was dependent on the density of the recombination centers and the probability that an electron would interact with the centre. Geometric models were presented to illustrate the processes of radiation damage assoc-iated with the quartz tetrahedral structures.