Abstract
Emission spectra of photoluminescence (PL) and thermoluminescence (TL) in pure Al 2O 3 and in Al 2O 3 doped with Si and Ti impurities have been studied. Ti impurity is shown to be correlated with a broad emission band at 3 eV which is attributed to crystal field transitions resulting from recombination of electrons with Ti 3+. The recombining electrons originate from F-centres and TL traps for PL and TL emission respectively. A sharp emission band at 1.78 eV in PL and TL results from Cr 3+ impurity present in pure Al 2O 3. The optical absorption spectra of Al 2O 3:Si, Ti studied by reflectance technique show a prominent F-band at 5.5 eV. A broad absorption band at 2.9-3.5 eV is produced by the optical bleaching of the F-band and also by gamma irradiation. This band is correlated with TL traps in Al 2O 3:Si, Ti.
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