Physical aging and phase transitions in polyamorphous glasses

Among the difficulties of studying the glass transition is the presence of underlying first-order transitions, such as crystallization, that must be avoided, or at least accounted for, in order to study the glassy slowing of microscopic rearrangements. Such first-order transitions include not only crystallization, but also more exotic liquid-liquid phase transitions. Such transitions are suspected to occur in common and important glass forming materials including water, silica, and even ordinary window glass. Classical nucleation theory offers insight into the properties of equilibrium crystal-liquid and liquid-liquid transitions but must be modified when the length scales of glassy rearrangements are comparable to the size of the critical nucleus. In this work, we extend the Random First-Order Transition theory (RFOT) of the glass transition to study models with inherent liquid-liquid phase transitions and describe how nucleation occurs in the glassy, aging regime to alternative liquid and crystal phases.