A study was made of the formation and decay of lattice defects in wide-bandgap optical crystals of LiB3O5, Li2B4O7 and Li6Gd(BO3)3 with a sub-lattice of mobile lithium cations. By means of thermoluminescence techniques, and luminescent and absorption optical spectroscopy with a nanosecond time resolution under excitation with an electron beam, it was revealed that the optical absorption in these crystals in the visible and ultraviolet spectral ranges was produced by optical hole-transitions from the local defect level to the valence band states. The valence band density of the states determines mainly the optical absorption spectral profile, and the relaxation kinetics was rated by the interdefect non-radiative tunnel recombination between the trapped-hole center and the Li0 trapped-electron centers. At 290K, the Li0 centers were subject to thermally stimulated migration. Based on experimental results, the overall picture of thermally stimulated recombination processes with the participation of shallow traps was established for these crystals.

Radiation Effects and Defects in Lithium Borate Crystals. I.N.Ogorodnikov, N.E.Poryvay, V.A.Pustovarov: IOP Conference Series - Materials Science and Engineering, 2010, 15[1], 012016