Kinetic model for phase transformation of noncrystalline solids: Application to permanent densification of SiO2 glass

The phase transformation of noncrystalline solids is quite different from that of crystalline solids. To gain a better understanding, a kinetic model for pressure-induced phase transformation of noncrystalline solids is constructed by formulating activation- and free-energy distributions. The model is applied to permanent densification of $\mathrm{Si}{\mathrm{O}}_{2}$ glass, which occurs as a result of a transformation in the network structure. The model is found to be effective in reproducing interesting behavior, including the existence of an infinite number of intermediate states, each of which has a distinct compression curve like a phase, and a halt in the transformation before completion even at sufficiently high temperatures.