POLYMORPHISM OF SHOCKED WATER

Phase transition phenomena in water under shock compression have been investigated on the basis of the shock-particle velocity correlation obtained by treatment of experimental data. The correlation is split up into three linear parts. The lower and higher pressure parts are identified as liquid phases, while the middle part is identified as the mixture of solid and liquid phases. The calculated values of the liquid phase temperature make it possible to compare a shock adiabat with the melting curve of Ice-VII in the pressure-temperature coordinates. The shock adiabat breaks in the shock-particle velocity correlation corresponding to the points of intersection of the shock water adiabat with the phase equilibrium of water-Ice-VII. Comparison of these data with those of other authors allows one to conclude that the shock adiabat of water is changing into the solid phase field of Ice-VII within the pressure region of 2-16 GPa. On the other hand, the value of the weight fraction of Ice-VII varies, it depends upon the pressure and changes from 0 to 0.25 in the pressure range (2.10) GPa.