Observation of the most H2-dense filled ice under high pressure

Hydrogen hydrates are among the basic constituents of our solar system's outer planets, some of their moons, as well Neptune-like exo-planets. The details of their high-pressure phases and their thermodynamic conditions of formation and stability are fundamental information for establishing the...

Full description

Saved in:
Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2023-12, Vol.120 (52), p.1-e2312665120
Main Authors: Ranieri, Umbertoluca, Cataldo, Simone Di, Rescigno, Maria, Monacelli, Lorenzo, Gaal, Richard, Santoro, Mario, Andriambariarijaona, Leon, Parisiades, Paraskevas, De, Cristiano, Bove, Livia
Format: Article
Language:English
Subjects:
Chemical synthesis
Crystal structure
Density functional theory
Extrasolar planets
First principles
High pressure
Hydrates
Hydrogen
Ice
Raman spectroscopy
Solar system
Stability
Stochasticity
X-ray diffraction
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Hydrogen hydrates are among the basic constituents of our solar system's outer planets, some of their moons, as well Neptune-like exo-planets. The details of their high-pressure phases and their thermodynamic conditions of formation and stability are fundamental information for establishing the presence of hydrogen hydrates in the interior of those celestial bodies, for example, against the presence of the pure components (water ice and molecular hydrogen). Here, we report a synthesis path and experimental observation, by X-ray diffraction and Raman spectroscopy measurements, of the most H2-dense phase of hydrogen hydrate so far reported, namely the compound 3 (or C3). The detailed characterisation of this hydrogen-filled ice, based on the crystal structure of cubic ice I (ice Ic), is performed by comparing the experimental observations with first-principles calculations based on density functional theory and the stochastic self-consistent harmonic approximation. We observe that the extreme (up to 90 GPa and likely beyond) pressure stability of this hydrate phase is due to the close-packed geometry of the hydrogen molecules caged in the ice I
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.2312665120