Similarity between Shock-Induced Polymorphic Transitions in the Silica System

A set of experimental data on the thermodynamic parameters of polymorphic transitions in the silica system is considered. Analysis of these parameters in dimensionless form is performed. A fundamental result of the analysis is that the thermodynamic parameters of all silica polymorphs after transitions are described by a single universal Hugoniot of polymorphic transition. It is shown that the two-shock model of polymorphic transformations proposed earlier by the author describes all the results obtained in the analysis. A joint consideration of the experimental data and model calculations leads to the conclusion that during a polymorphic transformation, the density of the new phase is determined from the condition that the elastic pressure components after the first shock and after the polymorphic transition are equal.