The phase diagram of high-pressure superionic ice

Jiming Sun, Bryan K. Clark, Salvatore Torquato, Roberto Car

Research output: Contribution to journalArticle

Abstract

Superionic ice is a special group of ice phases at high temperature and pressure, which may exist in ice-rich planets and exoplanets. In superionic ice liquid hydrogen coexists with a crystalline oxygen sublattice. At high pressures, the properties of superionic ice are largely unknown. Here we report evidence that from 280 GPa to 1.3 TPa, there are several competing phases within the close-packed oxygen sublattice. At even higher pressure, the close-packed structure of the oxygen sublattice becomes unstable to a new unusual superionic phase in which the oxygen sublattice takes the P21/c symmetry. We also discover that higher pressure phases have lower transition temperatures. The diffusive hydrogen in the P21/c superionic phase shows strong anisotropic behaviour and forms a quasi-two-dimensional liquid. The ionic conductivity changes abruptly in the solid to close-packed superionic phase transition, but continuously in the solid to P21/c superionic phase transition.

Original languageEnglish (US)
Article number8156
JournalNature communications
Volume6
DOIs
StatePublished - Aug 28 2015

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pressure ice
Ice
Phase diagrams
ice
sublattices
phase diagrams
Pressure
Oxygen
Phase Transition
oxygen
Hydrogen
Phase transitions
Planets
liquid hydrogen
Transition Temperature
Liquids
extrasolar planets
Ionic conductivity
ion currents
planets

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Chemistry(all)
  • Physics and Astronomy(all)

Cite this

The phase diagram of high-pressure superionic ice. / Sun, Jiming; Clark, Bryan K.; Torquato, Salvatore; Car, Roberto.

In: Nature communications, Vol. 6, 8156, 28.08.2015.

Research output: Contribution to journalArticle

Sun, Jiming ; Clark, Bryan K. ; Torquato, Salvatore ; Car, Roberto. / The phase diagram of high-pressure superionic ice. In: Nature communications. 2015 ; Vol. 6.
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