Water-carbon dioxide solid phase equilibria at pressures above 4 GPa

• Published in: Scientific Reports
• Main Authors: Abramson, E. H., Bollengier, O., Brown, J. M.
• Language: unknown
• Published: 2023
• Subjects: 54 ENVIRONMENTAL SCIENCES; Anvil; Carbonic acid
• Online Access: http://www.osti.gov/servlets/purl/1624284; https://www.osti.gov/biblio/1624284; https://doi.org/10.1038/s41598-017-00915-0

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 4.4GPa 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 6.5GPa and 20°C) of a=5.88Å, b=6.59Å, c=6.99Å, α=88.7°, β=79.7°, and γ=67.7°. Raman spectra exhibit a major line at ~1080cm-1 and lattice modes below 300cm-1.