Electrolytic Coloration And Mechanism Of Natural Grytals Crystals And Potassium Alum Crystals

In this thesis, natural gypsum crystals and potassium alum crystals were successfully colored electrolytically for the first time, and many 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.Before electrolysis, a color center adsorption band was observed at approx210nm. in the absorption spectra of uncolored gypsum crystals. This absorption band is not associated with any known color center, it may be caused by impurity or crystal properties. Color center adsorption band was not be found in potassium alum crystals.Under electrolytic coloration using a pointed cathode, at the proper temperature, voltage and time combination, a lot of SO4-, SO3-, SO2-, O3-and O-color centers were produced in natural fibrous gypsum crystals;a lot of SO3-, SO2-, O3-and O-color centers were produced in potassium alum crystals. The electrolysis success of natural fibrous gypsum crystals and potassium alum crystals should mainly benefit appropriate conditions and the used unique anode matrix. Color centers were produced firstly in crystal region near the anode matrix, and color centers diffuse to other region of natural fibrous gypsum through exchanging electrons with neighboring SO42-radicals. Through many experiments, the most effective coloration condition of natural gypsum crystals is at temperature363K, voltage1100V and electrolysis time60min was found the most effective coloration of potassium alum crystals is at temperature353K, voltage1100V and electrolysis time45min.Under electrolytic coloration using a pointed anode, at the proper temperature, voltage and time combination, and crystals were successfully coloration. the most effective coloration condition of natural gypsum crystals is at temperature363K, voltage1100V and electrolysis time90min was found the most effective coloration of potassium alum crystals is at temperature353K, voltage1100V and electrolysis time80min. The color center types and formation mechanism were similar to those using a pointed cathode.Current-time curves. Some electrons and small charged color centers such as O- O2-and O3-will be generated during the electrolysis, which were moving freely in the crystals. They exchange electrons with anode matrix. These can form current. Current-time curves were closely related to color center generation mechanism, so it is very necessary to record the current and time data, draw the current-time curves.