Relaxation of optical excitations in crystals of the Y2O3-Al2O3 system with radiation defects

The photoluminescence and short-time persistence (afterglow) kinetics in pure and doped Y2O3-Al2O3 crystals excited with UV laser pulses (12 ns, 337 nm) were studied using samples irradiated with gamma quanta from a 60Co source to a dose from 104 to 107 Gy. The relaxation time of the samples studied increases, with decreasing symmetry of the crystal lattice, in the following order: garnet—orthoaluminate—ruby—yttria. The afterglow duration and intensity significantly decrease in gamma-irradiated crystals, which is explained by the predominant recombination of close electron-hole pairs. Garnet-neodymium crystals are characterized by high radiation stability and fast relaxation kinetics.