7: Density and Thermal Expansion

Density, molar volume, and thermal expansion coefficients are determined by the structure and bonding within a glass, and are therefore strongly affected by changes in glass composition. Phase separation has little effect on these properties. The glass transformation and dilatometric softening temperatures are related to the viscosity of the melt, and are strongly affected by both the composition of the glass and by the microstructure of phase separated glasses. All of these properties are altered by crystallization.