The crystal structure of methane B at 8 GPa—An α-Mn arrangement of molecules

Journal Article · Sun Dec 21 00:00:00 EST 2014 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4903813· OSTI ID:22413342

Lundegaard, L. F.; Loa, I.; McMahon, M. I.; Gregoryanz, E.; Nelmes, R. J.; Loveday, J. S. ^[1]

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1. SUPA, School of Physics and Astronomy and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)

From a combination of powder and single-crystal synchrotron x-ray diffraction data we have determined the carbon substructure of phase B of methane at a pressure of ∼8 GPa. We find this substructure to be cubic with space group I4{sup ¯}3m and 58 molecules in the unit cell. The unit cell has a lattice parameter a = 11.911(1) Å at 8.3(2) GPa, which is a factor of √2 larger than had previously been proposed by Umemoto et al. [J. Phys.: Condens. Matter 14, 10675 (2002)]. The substructure as now solved is not related to any close-packed arrangement, contrary to previous proposals. Surprisingly, the arrangement of the carbon atoms is isostructural with that of α-manganese at ambient conditions.

• OSTI ID: 22413342
• Journal Information: Journal of Chemical Physics, Vol. 141, Issue 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON
CRYSTAL STRUCTURE
LATTICE PARAMETERS
MANGANESE
METHANE
MOLECULES
MONOCRYSTALS
POWDERS
PROPOSALS
SPACE GROUPS
SYNCHROTRONS
X-RAY DIFFRACTION