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Phases modulées et centrage du proton dans la glace par diffraction des rayons X à des pressions jusqu'à 170 gigapascals.

Modulated phases and proton centring in ice observed by X-ray diffraction up to 170 gigapascals.

Auteurs : LOUBEYRE P., LETOULLEC R., WOLANIN E., HANFLAND M., HAUSERMANN D.

Type d'article : Article

Résumé

Crystallographic studies had previously been extended to pressures of up to 20 gigapascals, which is however insufficient to permit the investigation of ice X, a "symmetric ice" in which the protons are thought to reside midway between the oxygen atoms. The authors showed that single-crystal X-ray diffraction is able to reveal the signature of hydrogen-bond symmetrization. The 111 reflection can be assigned to the hydrogen atoms alone, and they were able to measure it up to 170 gigapascals in a diamond anvil cell. This diffraction line indicates that the proton centring in ice X occurs from about 60 to 150 gigapascals; at this latter pressure the intensity increases sharply, signalling a further structural change. At lower pressures, they observed ice VII ordering in a sequence of spatially modulated phases between 2.2 and 25 gigapascals.

Détails

  • Titre original : Modulated phases and proton centring in ice observed by X-ray diffraction up to 170 gigapascals.
  • Identifiant de la fiche : 1999-3358
  • Langues : Anglais
  • Source : Nature - vol. 397 - n. 6719
  • Date d'édition : 11/02/1999
  • Document disponible en consultation à la bibliothèque du siège de l'IIF uniquement.

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