Bond character and properties of the mixed alkali system Na2OK2OAl2O3SiO2 |
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Authors: | A Klonkowski |
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Institution: | Arbeitsgruppe Glas, Technische Universität Clausthal, Fed. Rep. Germany |
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Abstract: | The mixed alkali glass system Na2OK2OAl2O3SiO2 was investigated. Density, transformation temperature, refractive index, and chemical durability were studied. Optical absorption and ESR spectra of the CuO-doped glasses were determined.Calculations of the polarizability of O2?, bonding parameters of the Cu2+ complex, and the packing density are presented. It was found that for the mixed alkali glasses, the oxygen- alkali bond has a more ionic character than expected from additivity. This fact enables the non-linear changes of the refractive index, of the shift of the Cu2+ absorption band, and of the covalency to be interpreted as the Na mole fraction is varied. It is also possible to explain qualitatively the density, Tg and chemical durability non-linear variations with change of the Na content by the ionicity deviations of the bond character and the postulated pairs of Na+ and K+ ions in the mixed alkali glasses. |
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