Emission and excitation spectra and decay kinetics are studied for the luminescence of undoped LuAG and YAG crystals. Two emission bands are located at 4.8 eV and 3.95 eV in YAG and 4.9 eV and 3.65 eV in LuAG, excited in the E exc >6.5 eV energy region. ). The corresponding excitation band, peaking at 6.9 eV in YAG and 7.2 eV in LuAG, is ascribed to the exciton perturbed by the antisite defect. Besides the two slow emissions, the weak fast (ns) emission of the self-trapped exciton, strongly overlapping with the high-energy emission band, is also observed. In Ce 3+ -doped garnets, the presence of the antisite defects results in a considerable decrease of energy transfer efficiency from the host lattice to Ce 3+ ions. The possibilities of improvement of scintillation charactristics of this material are discussed.

PACS 78.55.Hx, 78.60.Kn Luminescence, energy transfer and defects creation processes were studied at 4.2 -300 K for Ce 3+ -doped Lu 3 Al 5 O 12 crystals under excitation in the 2.5 -11.5 eV energy range. The results obtained were compared with the characteristics of Y 3 Al 5 O 12 : Ce crystals. It was concluded that in both systems the efficiency of energy transfer from the host lattice to the impurity ion can be noticeably increased by the decrease of concentration of the defects responsible for their intrinsic luminescence. The origin of the optically created defects and possible mechanisms of their formation are discussed.

Luminescence, energy transfer and defects creation processes were studied for the Ce 3+ -doped YAlO 3 and Lu x Y 1-x AlO 3 (x = 0.3) crystals in the temperature range 4.2 -300 K under selective photoexcitation in the energy range 3.5 -11.5 eV. For the first time, defects creation spectra were measured and analyzed. Influence of the charge and ionic radii of co-doping ions on the luminescence and defects creation efficiency was considered. The origin of the defects created and possible mechanisms of their formation were discussed.

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