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If the SrCl2-Tl+ crystals get irradiated with ionizing radiation at a temperature of 80-150 K, the low-temperature color centers appear in them, having surplus electric charge relative to the lattice as a result of capturing electrons and holes by the impurity-vacancy dipoles. If the crystal is irradiated at temperatures above 150 K, when the anionic vacancies can migrate, the high-temperature color centers emerge, which are electrically neutral relative to the lattice. Hence, the coloration of crystal is more effective at high temperatures. However, if the crystal irradiated at high temperatures is cooled down to 80 K, then discolored and re-irradiated with ionizing radiation, both types of color centers are effectively generated in it. Namely, SrCl2-Tl+ crystals have "radiation memory" and, as a result of such modifications, the effectiveness of crystal coloration at low temperatures increases several times. The parameters of radiation sensitivity of the SrCl2-Tl+ crystals were calculated in a one-dimensional model. The limit concentrations of the color centers as a function of the concentration of the Tl+-impurity in the crystal were defined. The calculation results are in good agreement with the experimental data, which confirms the validity of using such a one-dimensional model for predicting the radiation properties of real crystals and searching for ways to increase the effectiveness of crystal coloration. [ABSTRACT FROM AUTHOR]

The parameters of radiation sensitivity of the oxygen-doped fluorite crystals were calculated in a one-dimensional model. The limit concentrations of the color centers as a function of the concentration of the oxygen impurity in the fluorite crystal were defined. Fluorite crystals with anti-Frenkel defects in the anion sublattice of the crystal have a specific property: the discolored after irradiation crystal being irradiated repeatedly with ionizing radiation retains the "memory" of the preceding irradiation. Using an ion chain model this paper studies under what conditions the "radiation memory" effect can arise in the MeF2-O2- crystals as well as the extent of its contribution into the overall radiation sensitivity of the crystal. [ABSTRACT FROM AUTHOR]

In fluorite crystals doped with alkali metals a new electronic FD-center colouring has been discovered. This center is an F-center located in the vicinity of the impurity vacancy dipole. The FD-center occurs in the repeated exposure of optically discoloured crystals in M+A -lines of absorption and is formed due to the localization of zone electrons in the band of two vacancy complexes: e- + V⋅a Me'V⋅a → V0a Me'V⋅a where e- is a band electron; V⋅a is an anion vacancy; Me' is an alkali metal ion; V0a is an F-center; V0a Me'V⋅a is an FD-center. FD-center are thermally stable at the temperatures of T < Tr (Tr is the temperature rotation IVD). At T > Tr FD-centers are transformed into M+A-centers: … [ABSTRACT FROM AUTHOR]