Ice VII is the only disordered phase of ice that can be ordered by simple cooling. (While ice I h theoretically transforms into proton-ordered ice XI on geologic timescales, in practice it is necessary to add small amounts of KOH catalyst.) It forms …

Ice-eight (ice VIII) forms from ice-seven (ice VII) on lowering its temperature (see Phase Diagram). The hydrogen bonding is ordered and fixed as ice-seven undergoes a proton disorder-order transition to ice eight when cooled at about 5 °C; ice-seven and ice-eight having identical structures apart from the proton ordering.

Jul 16, 2003 · Substitution of hydrogen with deuterium pushes the boundary between the molecular (VII, VIII) and nonmolecular (X) ice phases toward higher pressures by 12–14 GPa, indicating clearly isotope effect on the phase transition due to dynamical translational disordering.

Ice-eight (ice VIII) is formed from ice-seven (ice VII) by lowering its temperature (see Phase Diagram).The hydrogen bonding is ordered and fixed as ice-seven undergoes a proton disorder- order transition to ice eight when cooled at about 5 °C; ice-seven and ice-eight having identical

Nov 14, 2016 · Here, we present a potential model for this hidden force opposing ice compression of ice VIII-X phase transition based on the density functional theory (DFT) and neutron scattering...

Mar 19, 1998 · We find that the proton-ordered structure at low pressure, with asymmetric hydrogen bonds (ice VIII), transforms on increasing pressure to a proton-disordered asymmetric phase (ice VII) owing...

Jan 31, 2024 · The phonon dispersion of ice VII and that of its proton-ordered analog ice VIII are investigated through a combination of inelastic x-ray scattering (IXS) measurements and first-principles calculations of the oxygen sublattice dynamic structure factor.

Oct 1, 2022 · Water is known to have a complex phase diagram with numerous solid polymorphs, one of which is ice VIII, a proton ordered high pressure form of ice. In this work the mechanical properties of ice VIII were studied through the use of first principles density functional theory (DFT) simulations.

May 22, 2019 · Ice IX, ice XV and ice VIII are three of at least 17 ice phases realized when molecules reorganize into a stable crystalline structure at varying super-low temperatures and very high pressures, conditions that don’t occur naturally on Earth.

May 1, 1994 · Variations of the a and c parameters of tetragonal ice VIII, as well as those of the internal atomic coordinates of oxygen and deuterium are reported and discussed. Isothermal equations of state for ice VIII between 0 and 300 K are established.