Electroly Electrolytic Tic Coloration Of Sodium Fluoride Crystals And Mechanism Of Production And Transformation Of Color Centers

Using electrolysis technique, air-grown NaF crystals were successfully colored electrolytically for the first time, and a lot of color centers were produced in the colored crystals. Spectral observation and analysis were performed systematically to the colored crystals, and production and transformation mechanism of color centers were presented; by using measured current-time curves and calculated activation energy of V color centers, the process and mechanism of the color center production of explained further, which lay a foundation for further research and application of color center crystals. For comparison, NaF crystals were irradiated byγ–rays and corresponding productive and transformation of color centers was explained.A lot of O2-, F, M, N1 and N2 color centers were produced in the air-grown NaF crystals after the electrolytic coloration with a pointed cathode, some absorption spectra of the colored crystals were decomposed, and spectral parameters of various color centers were determined accurately. Using traditional electrolysis method, the air-grown NaF crystals are hardly colored because the crystals contain a lot of anions like O2- and O2--Va+. In this work, the electrolysis success should mainly benefit the used unique anode matrix, which makes the V color centers are produced firstly, and the V color centers are converted into F color center under light illumination, then, some F color centers are aggregated into M, N1 and N2 color centers. After many electrolytic colorations at various temperatures and voltages, an optimal coloration condition at about 743 K temperature, 1500 V voltage and 4.0 h electrified time is found. According to the measured data, an activation energy of 0.91 eV for the V color center migration is calculated, and it is presented that the V color center migration is realized through electron exchange of interstitial atom in the V color center with neighboring interstitial halogen ion. Current-time curves were measured. It is pointed that the main component consists of electron exchange between halogen ions and anode matrix, and in the meantime, original V color centers are produced. Formation mechanism explanation of current zones in the current-time curves is presented, and close relationship between the current zones and color center production is given. After electrolytic coloration with a pointed anode, current-time curves in the electrolysis process of air-grown NaF crystals were measured, and it is...