Radiation-induced transformations of luminescence centers in anion-defective alumina crystals under high-dose irradiations

• Alumina crystals (Al2O3:C) were studied after exposures with doses up to 106 Gy.
• PL and PLE spectra of alumina crystals were measured after exposure to high-dose.
• New wide emission band was found in the PL spectra of irradiated crystals.
• High dose irradiations give rise to charged aggregate F2-type centers.
• Aggregate centers are responsible for the change in PL spectra and TL yield.

Luminescent spectroscopy is used to show formation of new trapping centers of charge carriers in anion-defective alumina crystals at radiation-induced transformations of F and F+-centers created by oxygen vacancies when exposed to high-dose gamma-radiation. A new wide band in the range 440–700 nm was registered in the photoluminescence spectrum at excitations with UV photons. High-dose irradiation of the crystals leads to appearance of F2-type aggregate centers in different charged states. These centers are additional traps of charge carriers. The new traps increase a luminescent yield at high-dose irradiation with gamma-rays and an electron beam.