Point defects in neutron-irradiated quartz

Point defects formed by irradiation with fast neutrons have been characterized in high-quality synthetic quartz using electron spin resonance and optical absorption techniques. Among the paramagnetic defects generated are the E′1 center, the [AlO4]0 center, and two previously unreported S=1 centers. Production and thermal annealing characteristics of these more prominent defects are described. The two S=1 defects have gc values of 2.0205 and 2.0158 and thermally decay near 250 and 470 °C, respectively. They each consist of a pair of unpaired spins (i.e., holes) separated by approximately 5 Å, and either vacancies or interstitials are a part of their models. These latter two centers, along with the E1 centers, result from direct displacements during the neutron irradiation. An optical absorption band at 210 nm grows at the same rate during irradiation as the E′1 centers and S=1 centers but cannot be definitely assigned to particular defects.