ESR and luminescent properties of anion-deficient α-Al2O3 single crystals after high-dose irradiation by a pulsed electron beam

Electron spin resonance (ESR) and photoluminescence (PL) spectra of anion-deficient alumina single crystals were measured. High-dose irradiation by a pulsed electron beam (130 keV) causes an absorption line with g(perpendicular to) = 2.008 +/- 0.002 in the ESR spectrum. In contrast to the irradiation by the beta-source, there is no overlapping of this line with another one in the obtained ESR spectrum, which allowed to investigate the thermal stability of this line more in details and to prove that it consists of several elementary components. A drop in PL intensity of F+-centers (3.8 eV) and F-centers (3.0 eV) is observed with increasing of ESR absorption line with g(perpendicular to) = 2.008 +/- 0.002. Parallel studies of ESR and PL spectra under stepped annealing in the temperature range of 523-973 K showed that the radiation-induced paramagnetic center was stable up to 873-973 K. A possible association of the disappearance of the ESR absorption line with the destruction of F-type aggregate defect and with changing charge state of the paramagnetic center caused by emptying of deep electron and hole traps at T = 773-973 K is discussed in the paper.