Relationship Between Structure And Glass Transition Temperature In Low-Silica Calcium Aluminosilicate Glasses: The Origin Of The Anomaly At Low Silica Content

The anomalous behaviour of the glass transition temperature (Tg) in low silica calcium aluminosilicate glasses has been related to the structural modifications observed by neutron and X-ray diffraction. The diffraction data indicate that Al and Si are in tetrahedral sites and that Ca atoms are in distorted octahedral sites. By subtracting the correlation functions for glasses at constant SiO2 or constant Al2O3 content, it is shown that Si and Al atoms are introduced in a different way within the glass structure.