The distorted close-packed crystal structure of methane A

H. E. Maynard-Casely, C. L. Bull, M. Guthrie, I. Loa, M. I. McMahon, E. Gregoryanz, R. J. Nelmes, John Loveday, Malcolm McMahon

Research output: Contribution to journalArticlepeer-review

Abstract

We have determined the full crystal structure of the high-pressure phase methane A. X-ray single-crystal diffraction data were used to determine the carbon-atom arrangement, and neutron powder diffraction data from a deuterated sample allowed the deuterium atoms to be located. It was then possible to refine all the hydrogen positions from the single-crystal x-ray data. The structure has 21 molecules in a rhombohedral unit cell, and is quite strongly distorted from the cubic close-packed structure of methane I, although some structural similarities remain. Full knowledge of this structure is important for modeling of methane at higher pressures, including in relation to the mineralogy of the outer solar system. We discuss interesting structural parallels with the carbon tetrahalides. (C) 2010 American Institute of Physics. [doi:10.1063/1.3455889]

Original languageEnglish
Article number064504
Pages (from-to)-
Number of pages10
JournalThe Journal of Chemical Physics
Volume133
Issue number6
DOIs
Publication statusPublished - 14 Aug 2010

Keywords

  • crystal structure
  • neutron diffraction
  • organic compounds
  • X-ray diffraction
  • X-RAY-DIFFRACTION
  • HIGH-PRESSURE
  • SOLID METHANE
  • CARBON TETRAFLUORIDE
  • NEUTRON-DIFFRACTION
  • PHASE-TRANSITIONS
  • TEMPERATURE
  • GPA
  • CRYSTALLOGRAPHY
  • TETRACHLORIDE

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