title: Water-carbon dioxide solid phase equilibria at pressures above 4 GPa.
abstract: A solid phase in the mixed water-carbon dioxide system, previously identified as carbonic acid, was observed in the high-pressure diamond-anvil cell. The pressure-temperature paths of both its melting and peritectic curves were measured, beginning at 4.4 GPa and 165 °C (where it exists in a quadruple equilibrium, together with an aqueous fluid and the ices H2O(VII) and CO2(I)) and proceeding to higher pressures and temperatures. Single-crystal X-ray diffraction revealed a triclinic crystal with unit cell parameters (at 6.5 GPa and 20 °C) of a = 5.88 Å, b = 6.59 Å, c = 6.99 Å, α = 88.7°, β = 79.7°, and γ = 67.7°. Raman spectra exhibit a major line at ~1080 cm-1and lattice modes below 300 cm-1.
authors.affiliation: Department of Earth and Space Sciences, University of Washington, Seattle, WA, 98195-1310, USA. evan@ess.washington.edu.
authors.forename: E H
authors.identifier: http://orcid.org/0000-0001-5278-0836
authors.initials: EH
authors.lastname: Abramson
authors.affiliation: Department of Earth and Space Sciences, University of Washington, Seattle, WA, 98195-1310, USA.
authors.forename: O
authors.initials: O
authors.lastname: Bollengier
authors.affiliation: Department of Earth and Space Sciences, University of Washington, Seattle, WA, 98195-1310, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Brown