Equation of state of ice VII up to 106 GPa

Abstract

Using angle-dispersive x-ray powder diffraction and image plate detector, the equations of state of ${\mathrm{H}}_{2}\mathrm{O}$ and ${\mathrm{D}}_{2}\mathrm{O}$ ice VII, corrected for deviatoric strain, were determined up to 106 GPa, and 60 GPa, respectively. Our data were analyzed on the basis of the universal equation of state of Vinet et al. This treatment indicates the occurrence of two second- or higher-order phase transitions at about 15 and 66 GPa, in agreement with the pressure ranges where the nature of the proton disorder is expected to change.