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

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Date
2014-12-18
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AIP Scitation
Abstract
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 ¯ 3m I4¯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. Matter14, 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. © 2014, AIP Publishing LLC.
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Keywords
X-ray diffraction, Synchrotrons, Data, Molecules, Carbon, Atoms
Citation
Maynard-Casely, H. E., Lundegaard, L. F., Loa, I., McMahon, M. I., Gregoryanz, E., Nelmes, R. J., & Loveday, J. S. (2014). The crystal structure of methane B at 8 GPa—an α-Mn arrangement of molecules. The Journal of Chemical Physics, 141(23), 234313. doi: doi:10.1063/1.4903813
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