Luminescence of F+ and F centers in AI2O3-Y2O3 oxide compounds

We summarize the results of investigation of spectral-kinetic characteristics of the luminescence of F+ and F-centers in Al2O3, YAlO3 (YAP) and Y3Al5O12 (YAG) crystals under excitation by synchrotron radiation in the transmittance and fundamental absorption ranges of these oxides. We show that the luminescence of F+ and F centers in the mentioned crystals can be excited via the corresponding intrinsic 1A?2A, 2B and 3P (F+) and 1S?3P, 1P (F) transitions of these centers, as well as via the radiative relaxation of excitons localized around F+ and F centers. In YAG crystal fast (2.3 ns) emission in the 400 nm band, excited at 3.33, 5.37 and 6.56 eV, arises from the F+-type centers, localized around YAl antisite defects (ADs). In Al2O3 and YAP crystals, the luminescence of excitons localized around F+ centers (LE(F+) centers) is revealed and the energies of formation of such excitons are determined as well. In YAG crystal the observation of the luminescence of LE(F+) centers is obscured due to presence of the large content (~0.2 at.%) of YAl ADs and formation of an excitons localized around YAl ADs and dimer F+-ADs centers.