We report continuous glass formation and glass transition temperatures Tg for the pseudo-binary systems xM2O (1 - x) (0.87B2O30.13Al2O3) to x = 0.675 for M = Na and 0.575 for M = Li. A dependence of both Tg and glass-forming range on starting materials is found at high alkali contents, and attributed to retained CO2. Maxima in Tg for both binary and pseudo-binary systems are quantitatively described in terms of two effects: (i) creation of 4-coordinated borons (increasing Tg), and (ii) creation of non-bridging [BO3] oxygens (decreasing Tg. To first approximation we find the latter imparting a stronger effect on Tg.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry