title: Effect of salt on the H-bond symmetrization in ice.
abstract: The richness of the phase diagram of water reduces drastically at very high pressures where only two molecular phases, proton-disordered ice VII and proton-ordered ice VIII, are known. Both phases transform to the centered hydrogen bond atomic phase ice X above about 60 GPa, i.e., at pressures experienced in the interior of large ice bodies in the universe, such as Saturn and Neptune, where nonmolecular ice is thought to be the most abundant phase of water. In this work, we investigate, by Raman spectroscopy up to megabar pressures and ab initio simulations, how the transformation of ice VII in ice X is affected by the presence of salt inclusions in the ice lattice. Considerable amounts of salt can be included in ice VII structure under pressure via rock-ice interaction at depth and processes occurring during planetary accretion. Our study reveals that the presence of salt hinders proton order and hydrogen bond symmetrization, and pushes ice VII to ice X transformation to higher and higher pressures as the concentration of salt is increased.
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR 7590, Université Pierre et Marie Curie, F-75252 Paris, France; Institute of Condensed Matter Physics, Ecole Polytechnique Federal de Lausanne, CH-1015 Lausanne, Switzerland; livia.bove@impmc.jussieu.fr.
authors.forename: Livia Eleonora
authors.initials: LE
authors.lastname: Bove
authors.affiliation: Institute of Condensed Matter Physics, Ecole Polytechnique Federal de Lausanne, CH-1015 Lausanne, Switzerland;
authors.forename: Richard
authors.initials: R
authors.lastname: Gaal
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR 7590, Université Pierre et Marie Curie, F-75252 Paris, France; Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linkoping, Sweden;
authors.forename: Zamaan
authors.initials: Z
authors.lastname: Raza
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR 7590, Université Pierre et Marie Curie, F-75252 Paris, France;
authors.forename: Adriaan-Alexander
authors.initials: AA
authors.lastname: Ludl
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR 7590, Université Pierre et Marie Curie, F-75252 Paris, France;
authors.forename: Stefan
authors.initials: S
authors.lastname: Klotz
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR 7590, Université Pierre et Marie Curie, F-75252 Paris, France;
authors.forename: Antonino Marco
authors.initials: AM
authors.lastname: Saitta
authors.affiliation: Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015.
authors.forename: Alexander F
authors.initials: AF
authors.lastname: Goncharov
authors.affiliation: Institute of Condensed Matter Physics, Ecole Polytechnique Federal de Lausanne, CH-1015 Lausanne, Switzerland;
authors.forename: Philippe
authors.initials: P
authors.lastname: Gillet
keywords: H-bond symmetrization; extreme conditions; ice bodies; proton quantum effects; salty ices