Experimental evidence of superionic conduction in H2O ice

Sugimura, Emiko; Komabayashi, Tetsuya; Ohta, Kenji; Hirose, Kei; Ohishi, Yasuo; Dubrovinsky, Leonid

doi:10.1063/1.4766816

Cited by 62 publications

(39 citation statements)

References 28 publications

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“…The prediction that ice enters a superionic state 162 has been validated experimentally. 69,[163][164][165] Similar predictions have been made for ammonia. 162 Moreover, full ionization of ammonia to contains H À (blue) and H 2 (white), 83 ) (i.e.…”

Section: Predictions For Experimentssupporting

confidence: 74%

Predicting crystal structures and properties of matter under extreme conditions via quantum mechanics: the pressure is on

Zurek

Grochala

2015

Phys. Chem. Chem. Phys.

113

107

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Experimental studies of compressed matter are now routinely conducted at pressures exceeding 1 mln atm (100 GPa) and occasionally at pressures greater than 10 mln atm (1 TPa). The structure and properties of solids that have been so significantly squeezed differ considerably from those of solids at ambient pressure (1 atm), often leading to new and unexpected physics. Chemical reactivity is also substantially altered in the extreme pressure regime. In this feature paper we describe how synergy between theory and experiment can pave the road towards new experimental discoveries. Because chemical rules-of-thumb established at 1 atm often fail to predict the structures of solids under high pressure, automated crystal structure prediction (CSP) methods are increasingly employed. After outlining the most important CSP techniques, we showcase a few examples from the recent literature that exemplify just how useful theory can be as an aid in the interpretation of experimental data, describe exciting theoretical predictions that are guiding experiment, and discuss when the computational methods that are currently routinely employed fail. Finally, we forecast important problems that will be targeted by theory as theoretical methods undergo rapid development, along with the simultaneous increase of computational power.

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Section: Predictions For Experimentssupporting

confidence: 74%

Predicting crystal structures and properties of matter under extreme conditions via quantum mechanics: the pressure is on

Zurek

Grochala

2015

Phys. Chem. Chem. Phys.

113

107

View full text Add to dashboard Cite

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“…This ice phase is thought to be the dominant phase of the interior of giant icy planets and may be responsible for the observed anomalous magnetic moment of Uranus and Neptune. Recent studies showed experimental evidence for superionic conduction at significantly low temperature compared with earlier theoretical estimates (17,18,50). The presence of salt impurities in natural ice, incorporated via ocean-ice interaction, rock-ice interaction at depth, or processes that occurred during accretion (1,2,(23)(24)(25), could strongly modify the thermodynamic conditions and the mechanism for the appearance of change in such an extreme state of matter, and eventually promote novel exotic properties, thus challenging our present description of the physics of these bodies, essentially based on the assumption of the properties of pure ice under high pressure.…”

Section: Resultsmentioning

confidence: 99%

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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“…8 Whether H 2 O is in the superionic or liquid state in the planetary interior is of great importance to understanding the source of the planetary magnetic field. 9,10 Although some experimental studies reported the existence of the superionic phase, 11,12 recent measurements of the melting temperature of H 2 O above the superionic phase show low melting temperatures and a quite gentle melting curve compared with those of the QMD prediction, 13 which implies that H 2 O should remain in the liquid state even at deep interior conditions. This discrepancy between experimental and theoretical studies suggests that the QMD based EOS model is disputable for modeling the planetary interior.…”

Section: Introductionmentioning

confidence: 95%

P-ρ-T measurements of H2O up to 260 GPa under laser-driven shock loading

Kimura

Ozaki

Sano

et al. 2015

The Journal of Chemical Physics

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Pressure, density, and temperature data for H2O were obtained up to 260 GPa by using laser-driven shock compression technique. The shock compression technique combined with the diamond anvil cell was used to assess the equation of state models for the P-ρ-T conditions for both the principal Hugoniot and the off-Hugoniot states. The contrast between the models allowed for a clear assessment of the equation of state models. Our P-ρ-T data totally agree with those of the model based on quantum molecular dynamics calculations. These facts indicate that this model is adopted as the standard for modeling interior structures of Neptune, Uranus, and exoplanets in the liquid phase in the multi-Mbar range.

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Experimental evidence of superionic conduction in H2O ice

Cited by 62 publications

References 28 publications

Predicting crystal structures and properties of matter under extreme conditions via quantum mechanics: the pressure is on

Predicting crystal structures and properties of matter under extreme conditions via quantum mechanics: the pressure is on

Effect of salt on the H-bond symmetrization in ice

P-ρ-T measurements of H2O up to 260 GPa under laser-driven shock loading

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