4: Immiscibility/Phase Separation

Liquid–liquid immiscibility is a common phenomenon in glass forming melts. Understanding of immiscibility is based on the thermodynamics of regular solutions. The separation process can yield glasses with either droplet/matrix or interconnected microstructures. Immiscibility diagrams are used to indicate the regions of immiscibility and the compositions and concentrations of the co-existing phases. A number of commercial products are based on phase separated glasses, especially those in the sodium borosilicate system.