Thermal annealing of neutron irradiation generated paramagnetic defects in transparent Al2O3 ceramics

It is fundamentally important to understand, control, and predict the effect of irradiation on the structure and optical properties of functional materials. In this work, the thermal stability of fast-neutron induced point defects has been investigated in polycrystalline transparent alumina ceramics. The results of a combined study of electron paramagnetic resonance (EPR) and photoluminescence spectroscopy are presented in this paper. The EPR signals related to different trapped-hole centers as well as electron-type F+ centers have been observed after neutron irradiation. Rapid decay of the total EPR signal intensity occurs after annealing in 600–750 K temperature range. The selective luminescence bands related to the F- and F2-type centers are detected under irradiated corundum ceramics photoexcitation within relevant defect absorption bands (i.e. intracenter excitation/emission).