The results were presented of a study of the radiation-induced processes and defects in non-linear optical crystals Li2B4O7, LiB3O5, CsLiB6O10, KB5O8·4H2O, β-BaB2O4. It was revealed that a pulsed electron beam irradiation at 290K formed radiation-induced pairs of the vacancy-interstitial atom defect-type in the cation sub-lattice. This gave rise to the creation of metastable electronic (interstitial atom) and hole (small-radius polaron near the cation vacancy) centers in high concentrations. Optical hole-transitions from the local level of the trapped hole centers to the valence band states were responsible for the transient optical absorption of borates in the visible and UV spectral ranges. A sub-lattice of the weakly bound mobile Li cations in Li2B4O7 and LiB3O5 favored a spatial separation of the radiation-induced pair defects; the so-called hole polaron near Li-vacancy-mobile interstitial Li0 atom.

Radiation-Induced Processes and Defects in Alkali and Alkaline-Earth Borate Crystals. I.N.Ogorodnikov, V.Y.Yakovlev, L.I.Isaenko: Radiation Measurements, 2004, 38[4-6], 659-62