Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 288

This condition is best exemplified by the x Na₂O·(1 − x) SiO₂ system where addition of Na₂O leads to conversion of bridging oxygens (with C = 2) into non‐bridging oxygens (with C = 1). The average value of degrees of freedom increases with increase in x:

(7)

It is well known that glass formation in alkali‐silicate systems becomes difficult for large value of x, especially when x > 0.5.