Phase separation and properties of lithium barium silicate glasses

Lithium barium silicate glasses are phase separated over most of the glass forming region. This study demonstrates that phase separation strongly affects some properties of these glasses, e.g. electrical conductivity, glass transformation temperature and dilatometric softening temperature, while other properties, including density, refractive index and thermal expansion coefficient, are not sensitive to the presence of phase separation. Changes in the morphology of the glass cause sharp changes in electrical conductivity and dilatometric softening temperature, while the glass transformation temperature is not affected by the morphology of the glass. The infrared spectrum of hydroxyl in the glass is also strongly affected by the presence of phase separation. Results of this study emphasise the interaction between effects of atomistic and morphololgic structures in controlling the properties of glasses.