The non-isothermal devitrification of glasses in the CaO center dot 4GeO(2)-SrO center dot 4GeO2 composition range

The effect of replacing CaO by SrO on the glass transition temperature and on devitrification behaviour in a series of glasses in the calcium tetrager manate-strontium tetragermanate composition range has been studied by diffe rential thermal analysis (DTA), X-ray diffraction (XRD) and Fourier-transfo rm infrared (FTLR) spectra. A similar GeO4/GeO6 molar ratio was found in al l the glasses of the series. The progressive replacing of CaO by SrO caused a decrease of the glass transition temperature. All glasses studied exhibi ted internal crystal nucleation. The crystallizing phases were identified a s CaGe4O9 and SrGe4O9. No solid solutions occur in glass containing both Ca O and SrO. The effect of the specific surface of the glass samples on devit rification processes has been studied. (C) 2001 Elsevier Science B.V. All r ights reserved.