High-pressure transformations in xenon hydrates | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  High-pressure transformations in xenon hydrates

Type de publication:

Journal Article

Source:

Proceedings of the National Academy of Sciences of the United States of America, Volume 99, Ticket 1, p.25-28 (2002)

URL:

<http://www.pnas.org/cgi/reprint/99/1/25>

Mots-clés:

Physico-chimie des fluides géologiques, UMR 7154

Résumé:

A high-pressure investigation of the Xe·H2O chemical system was conducted by using diamond-anvil cell techniques combined with in situ Raman spectroscopy, synchrotron x-ray diffraction, and laser heating. Structure I xenon clathrate was observed to be stable up to 1.8 GPa, at which pressure it transforms to a new Xe clathrate phase stable up to 2.5 GPa before breaking down to ice VII plus solid xenon. The bulk modulus and structure of both phases were determined: 9 ± 1 GPa for Xe clathrate A with structure I (cubic, a = 11.595 ± 0.003 Å, V = 1,558.9 ± 1.2 Å3 at 1.1 GPa) and 45 ± 5 GPa for Xe clathrate B (tetragonal, a = 8.320 ± 0.004 Å, c = 10.287 ± 0.007 Å, V = 712.1 ± 1.2 Å3 at 2.2 GPa). The extended pressure stability field of Xe clathrate structure I (A) and the discovery of a second Xe clathrate (B) above 1.8 GPa have implications for xenon in terrestrial and planetary interiors.