Ceramics-Silikáty 46, (2) 74 - 78 (2002) |
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MEASUREMENT OF OPTICAL TRANSMITTANCE - A NOVEL METHOD FOR DETERMINATION OF THE GLASS TRANSITION TEMPERATURE OF TRANSPARENT GLASSES
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Lichvár Peter 1, Galusek Dušan 1, Majling Ján 2,
Liška Marek 1
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1 Joint Laboratory of Glass of the Institute of Inorganic Chemistry of Slovak Academy of Sciences and of the Trenčín University
Študentská 2, 911 50 Trenčín, Slovak Republic
2 Department of Ceramics, Glass and Cement, Faculty of Chemical Technology, Slovak Technical University
Radlinského 9, 842 36 Bratislava, Slovak Republic
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Keywords: Glass transition temperature, Optical transmittance, Measurement
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A light beam thermal analysis (LBTA) has been applied for determination of the glass transition region (Tg) of Y₂O₃-Al₂O₃-
SiO₂ glasses containing between 0 and 20 mol.% of CaO. The temperature dependence of the optical transmittance of glass
plates with parallel surfaces and with controlled surface roughness was determined. Healing of defects on the glass surface
by viscous flow in the temperature region close to Tg was observed, resulting in increased transmission of visible light through
the specimen. The Tg values measured by LBTA are in a comparatively good agreement with the results obtained by differential
thermal analysis (DTA). |
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