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

Author(s) : LOUBEYRE P., LETOULLEC R., WOLANIN E., HANFLAND M., HAUSERMANN D.

Type of article: Article

Summary

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.

Details

  • Original title: Modulated phases and proton centring in ice observed by X-ray diffraction up to 170 gigapascals.
  • Record ID : 1999-3358
  • Languages: English
  • Source: Nature - vol. 397 - n. 6719
  • Publication date: 1999/02/11
  • Document available for consultation in the library of the IIR headquarters only.

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