Electrolytic Coloration Of Lithum Fluoride Crystals And Mechanism Of Production And Transformation Of Color Centers

In this thesis, oxygen-doped lithium fluoride crystals were successfully colored electrolytically for the first time, and a lot of color centers were produced in the colored crystals. Spectral measurement and analysis were performed systematically to the colored crystals, and production and transformation mechanisms of the color centers were presented. By using measured current-time curves, the production and transformation mechanisms of the color centers were further explained. For comparison, lithium fluoride crystals were irradiated by gamma ray and the production and transformation of the color centers were explained.After the electrolytic coloration using a pointed cathode, a lot of O^2--V_a⁺, O^2--V_a⁺ complex, magnesium-related impurity, Cu⁺, F, M, R₁, colloid, F₂⁺( Mg_c⁺), F₂⁺ :O^2- and F3 -centers were produced in oxygen-doped lithium fluoride crystals. In this work, the electrolysis success of the oxygen-doped lithium fluoride crystals should mainly benefit appropriate conditions and the used unique anode matrix, which makes the V centers are produced firstly inside the crystals nearby the anode. Therefore, the original color center produced by the electrolysis is the V color center and not the previous F color center. The migration of the V center is realized through electron exchange of interstitial atom in the V center with neighboring interstitial halogen ion, the V centers are converted into the F centers under light illumination, and then some F centers are aggregated into the M and F2+ centers etc. With measured current-time curves, it is known by reasoning that the current of the zone one mainly results from the ionic motion, and the current component produced by the electron exchanges is also included in the present first-zone current. The currents of the zones after the zone one mainly result from the electron exchanges, and the current components produced by the ionic motion are also included in the currents.In the case of the electrolytic coloration of the oxygen-doped lithium fluoride crystal using a pointed anode, several typical absorption spectra and current-time curves were offered. The formation mechanism of current zones in herein current-time curves is basically similar to that in above current-time curves using a pointed cathode.Lithium fluoride crystals were colored by gamma-ray irradiation with various doses. Experiment results showed that the species and concentration of the color centers were different with the difference of the irradiation dose. The required species and concentration of the color centers can be obtained according to the requirement in the actual application.