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- ItemFormation of radiation defects in Silicate and borosilicate glasses caused by UV lamp and excimer laser Irradiation(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Natura, Ute; Ehrt, DorisSolarization of colourless and coloured glasses of the type AR®, BK7® and DURAN® with high transmission in the UV-B region (280 to 320 nm) was investigated for their use as Container glasses in the solar disinfection of drinking water. The samples were coloured by doping with NiO or CoO. The influence of the Fe³⁺/Fe²⁺ content and of the reducing component Sn²⁺ was investigated on both the initial transmission of the glasses and the solarizadon. The samples were irradiated with a 1 kW Xe lamp and a XeCl excimer laser. The solarization depends on the glass matrix and is enhanced by colouring ions. The influence of Fe³⁺/Fe²⁺ and Sn²⁺ on the defect generation is different for glasses coloured with NiO than for those coloured with CoO. For the samples investigated it was possible to simulate the loss of transmission in the UV-B region due to long-time irradiation with sunlight by a laser experiment.
- ItemRedox behavior of iron and vanadium ions in Silicate melts at temperatures up to 2000 °C(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Leister, Michael; Ehrt, DorisTwo glasses 33Na₂O · 67SiO₂ and 15Na₂O · 85SiO₂ (composition in mol%), doped with Fe₂O₃ and V₂O₅, respectively, were melted under various conditions in the temperature ränge of 1400 to 2000 °C. The redox states in the quenched glasses were investigated by optical absorption spectroscopy. Investigations concerning the redox equilibrium of the polyvalent ions in the glass melts were carried out using square-wave voltammetry. The results of both methods were compared. Furthermore equilibrium experiments were carried out to show the time dependence of redox equilibrium reached.