Experimental study of the NaCl–H2O system up to 28GPa: Implications for ice-rich planetary bodies

Frank, Mark R.; Runge, Claire E.; Scott, H. P.; Maglio, S.; Olson, Jessica; Prakapenka, Vitali B.; Shen, Guoyin

doi:10.1016/j.pepi.2005.12.001

Cited by 36 publications

(59 citation statements)

References 54 publications

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“…Due to its high vitrification ability, LiCl-water also represents the ideal system to produce the salty amorphous ice phases serving as precursors for salty ice VII crystallization under pressure (37-39) (details are given in Sample Preparation). Despite a different ability to vitrify (47)(48)(49) and to undergo polyamorphic transitions at ambient and moderate pressures (39), LiCl and more naturally abundant NaCl produce very similar modifications on water structure and equations of state at high pressure (39)(40)(41)(42).…”

Section: Resultsmentioning

confidence: 99%

“…Recently, unexpected evidence has emerged that high-pressure water polymorphs can contain a substantial amount of small ions in salty ice structures (37)(38)(39)(40)(41)(42), and, similarly to what is observed in ice clathrates (43,44), they transform under pressure into bcc O lattices with ions either occupying interstices (37) or being substitutional to water molecules (37,39). These "filled" ice structures can be stable over several gigapascals and hundreds of Kelvins, conditions encountered in large ice bodies in the universe.…”

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confidence: 89%

“…These "filled" ice structures can be stable over several gigapascals and hundreds of Kelvins, conditions encountered in large ice bodies in the universe. Combined neutron scattering experiments and molecular dynamics simulations have allowed sketching of the pressure and Temperature (p-T) phase diagram of LiCl-water and NaCl-water mixtures up to a few gigapascals, and have shown that the presence of salt suppresses the ordered ice VIII phase and modifies the boundary of the proton-disordered ice VII phase (37)(38)(39)(40)(41)(42). Orientational disorder of water molecules is also enhanced by the presence of salt, as demonstrated by the Significance Ice-VII and ice-X phases are the most stable forms of ice at high temperature and extreme pressures, typical of the interiors of satellites and planets.…”

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confidence: 99%

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Effect of salt on the H-bond symmetrization in ice

Bove

Gáal

Raza

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The richness of the phase diagram of water reduces drastically at very high pressures where only two molecular phases, protondisordered 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.salty ices | extreme conditions | ice bodies | H-bond symmetrization | proton quantum effects A ll models of the interior of ice bodies in the universe rely on our knowledge of the behavior of a few simple molecules under high pressure and temperature (1-22), water being the most intriguing of them, due to its abundance and its connection to life existence.New data delivered by various space missions, such as the Voyager, Galileo, and Cassini-Huygens missions, have greatly improved our understanding of the icy bodies within the solar system (23-25), and recent discoveries of extrasolar planets with significant water ice content have highlighted the importance of high-pressure H 2 O-rich phases in planetary physics beyond the solar system (26).Water displays an unusually rich pressure-temperature phase diagram, which mainly derives from the open geometry of the water molecule, which favors tetrahedral arrangements, and from the possibility of configurational disorder of the protons in the lattice. However, at high pressure (above about 2 GPa), the system experiences a large densification as a result of the interpenetration of low-pressure structures, and only two molecular phases are known, ice VIII and VII (3, 4). Ice VII is composed of two interpenetrating but not interconnected tetrahedral hydrogen-bonded networks of water molecules of normal cubic ice, Ic, with a body-centered-cubic (bcc) oxygen structure. The orientation of the water molecules is disordered, resulting in a paraelectric phase. In the antiferroelectric ice VIII phase, the water molecules and the associated dipole moments on the two sublattices possess long-range order and point in opposite directions, promoting a slight tetragonal distortion of the cubic unit cell along the staggered polarization (3, 4). In these two phases, the hydrogen bonds are characterized by a pronounced double-well proton transfer potential. Upon reducing the distance between donor and acceptor oxygens, the proton potential degenerate...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 89%

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confidence: 99%

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Effect of salt on the H-bond symmetrization in ice

Bove

Gáal

Raza

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Frank et al (2006) presented a systematic study detailing the influence of charged species, Na + and Cl − , on the unit cell and OH bond length of ice VII. Based on the combination of the Raman and X-ray diffraction data, they hypothesized that the incorporation of those ions into ice VII resulted in a partial ordering of the protons by interionic attractions (Na + with O and Cl − with H), which resulted in a transition to an ice X-like structure, where the protons are equidistant between the oxygen atoms (Frank et al, 2006). However, their work was restricted to room temperature and, hence, did not cover a large enough PT range for confident application to planetary systems.…”

Section: Experimental and Analytical Methodsmentioning

confidence: 99%

“…This study examined an H 2 O-rich portion of the NaCl-H 2 O system at high pressure and high temperature to provide an improved first-order approximation of impurity-rich high-pressure H 2 O phases to be used in the next generation of phase stability and density profile models of H 2 O-rich bodies. The NaCl-H 2 O system was chosen due to its relative simplicity, well documented behavior over a large range of pressure and temperature, applicability to other ionic impurities, and as an extension of the room temperature, high-pressure work of Frank et al (2006). Although the direct applicability of this system to a specific planetary body is limited, this study will serve as a good first-order approximation on the impacts of impurities on the equation of state and melting curve of high-pressure phases of H 2 O and can be used as analogues for more complicated planetary systems.…”

Section: Introductionmentioning

confidence: 99%