Thermal- and photo-induced transformations of luminescence centers in alpha d-Al2O3 anion-defective crystals

Abstract

The thermal- and photo-induced transformations of luminescence centers in anion-defective crystals of α-Al 2O 3 have been investigated. It has been found that the exposure of crystals to ultraviolet light at temperatures in the range 50-900°C leads to substantial changes in their thermoluminescence and radioluminescence spectra. According to the optical absorption and photoluminescence data, the detected F-type centers have been identified and the temperature ranges of the F → F + → F 2 transformations and their possible mechanisms have been determined. The special attention has been drawn to the detailed similarity in the formation of complex F 2-type centers in the initially perfect α-Al 2O 3 crystals irradiated with fast neutrons and in the studied anion-defective crystals. © 2012 Pleiades Publishing, Ltd.