Skip to Main content Skip to Navigation
Journal articles

Dissociative melting of ice VII at high pressure

Abstract : We have used x-ray diffraction to determine the structure factor of water along its melting line to a static pressure of 57 GPa (570 kbar) and a temperature of more than 1500 K, conditions which correspond to the lower mantle of the Earth, and the interiors of Neptune and Uranus up to a depth of 7000 km. We have also performed corresponding first principles and classical molecular dynamics simulations. Above a pressure of 4 GPa the O-O structure factor is found to be very close to that of a simple soft sphere liquid, thus permitting us to determine the density of liquid water near the melting line. By comparing these results with the density of ice, also determined in this study, we find that the enthalpy of fusion (ΔHf) increases enormously along the melting line, reaching approximately 120 kJ/mole at 40 GPa (compared to 6 kJ/mole at 0 GPa), thus revealing significant molecular dissociation of water upon melting. We speculate that an extended two-phase region could occur in planetary processes involving the adiabatic compression of water.
Document type :
Journal articles
Complete list of metadata

https://hal-insu.archives-ouvertes.fr/insu-03604911
Contributor : Nathalie POTHIER Connect in order to contact the contributor
Submitted on : Thursday, March 10, 2022 - 4:43:16 PM
Last modification on : Thursday, June 9, 2022 - 8:20:09 AM

Identifiers

Citation

Alexander F. Goncharov, Chrystele Sanloup, Nir Goldman, Jonathan C. Crowhurst, Sorin Bastea, et al.. Dissociative melting of ice VII at high pressure. Journal of Chemical Physics, 2009, 130, pp.124514-124514. ⟨10.1063/1.3100771⟩. ⟨insu-03604911⟩

Share

Metrics

Record views

5