Filters

1995 - 19983

More filters

20243
Reset filters

Settings

Author: Harder, Ulrike × Publisher: Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Water release behaviour of soda-lime-silica glass melts
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1995) Gaber, Martin; Harder, Ulrike; Hähnert, Manfred; Geißler, Heinz
    Glass with the composiüon (in mol%) 16Na₂O * 10CaO * 74SiO₂ and a water content of 0.12 to 0.005 mol/1 has been investigated by IR spectroscopy. It has been found that at a water content of < 0.01 mol/l the rado of the extincdons of the absorpdon bands at 3550 and 2800 cm⁻¹ is not constant. Through the vacuum hot extraction method it could be shown that the release of bonded water from glass melt does not occur continuously, and is not determined by the kinetics of formadon of molecular water. At concentrations > 0.01 mol/l the largest part of bonded water is released at temperatures < 1000°C. Small amounts of water can be detected at temperatures > 1250°C as well. This high-temperature release of strongly bonded water is caused by changes in the structure of glass melt or by the simultaneous release of other volatile species.
  • Thumbnail Image
    Item
    Vibrational spectroscopic investigations of lead borate and lead aluminoborate glasses
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1996) Witke, Klaus; Harder, Ulrike; Willfahrt, Manfred; Hübert, Thomas; Reich, Peter
    Lead borate (PB) and lead aluminoborate (PBA) glasses in the Systems xPbO · ( 1 0 0 - x)Β₂O₃ (0 ≤ x ≤ 75 mol%) and xPbO · (95 - x)Β₂O₃, 5AI₂O₃ (0 ≤ x ≤ 80 mol%), respectively, have been prepared and investigated by Raman and infrared reflectance spectroscopy to obtain quahtative and quantitative information on the structure of glasses. Using the Martin-Brenig model, structural correlation lengths were determinated from boson peak positions of temperature-reduced Raman spectra and transversal sound velocities. Kramers-Kronig analysis was used to transform the measured infrared reflectance spectra into complex dielectric funcdons. The imaginary part of the complex dielectric funcdon contains the absorption properties of t he material. Α band separadon Computer programme has been used to get more detailed information from the spectra. Far infrared and low-frequency Raman spectra contain information about vibrations of the PbO component within the network.
  • Thumbnail Image
    Item
    Determination of the water content of alkali lime silica glasses by IR spectroscopy using nuclear reaction analysis for calibration
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1998) Harder, Ulrike; Geißler, Heinz; Gaber, Martin; Hähnert, Manfred; Dersch, Oliver; Rauch, Friedrich
    Systematic IR and NRA investigations were performed for two series of glasses with very different water contents. The glasses had the composition (in mol%): 16 R₂O · 10 CaO · 74 SiO₂ (R = sodium, potassium). The IR absorption coefTicients of the OH bands were found to be linearly correlated with the total hydrogen content obtained by the NRA measurements. Using the hydrogen concentration values from NRA, the total water contents were calculated and so-called practical IR extinction coefTicients were deduced. The values found for the soda-lime-silica glasses are 381 · mol¯¹ · cm¯¹ for the band at 3550cm¯¹ and 561 · mol¯¹ · cm¯¹ for the band at 2800cm¯¹. The values for the potassium-lime-silica glasses are 231 · mol¯¹ · cm¯¹ for the band at 3550 cm¯¹ and 78 l · mol¯¹ · cm¯¹ for the band at 2800 cm¯¹ Also, Scholze's two-band method was applied, resulting in good agreement between the water contents of the glasses derived from the IR and the NRA measurements.