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

H. E. Maynard-Casely; L. F. Lundegaard; I. Loa; M. I. McMahon; E. Gregoryanz; R. J. Nelmes; J. S. Loveday

doi:10.1063/1.4903813

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

H. E. Maynard-Casely^*, L. F. Lundegaard, I. Loa, M. I. McMahon, E. Gregoryanz, R. J. Nelmes, J. S. Loveday

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract / Description of output

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 similar to 8 GPa. We find this substructure to be cubic with space group I (4) over bar 3m and 58 molecules in the unit cell. The unit cell has a lattice parameter a = 11.911(1) angstrom at 8.3(2) GPa, which is a factor of root 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 a-manganese at ambient conditions. (C) 2014 AIP Publishing LLC.

Original language	English
Article number	234313
Number of pages	7
Journal	The Journal of Chemical Physics
Volume	141
Issue number	23
DOIs	https://doi.org/10.1063/1.4903813
Publication status	Published - 21 Dec 2014

Keywords / Materials (for Non-textual outputs)

X-RAY-DIFFRACTION
HIGH-PRESSURE
SOLID METHANE
SINGLE-CRYSTAL
ROOM-TEMPERATURE
DISSOCIATION
VOYAGER-2
INTERIORS
MANGANESE
CH4

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10.1063/1.4903813

2014_MLLM14_Methane-BFinal published version, 1.16 MB

John Loveday
- j.lovedayed.acuk
- School of Physics and Astronomy - Personal Chair of High-Pressure Chemical Physics
Person: Academic: Research Active

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title = "The crystal structure of methane B at 8 GPa-An alpha-Mn arrangement of molecules",

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 similar to 8 GPa. We find this substructure to be cubic with space group I (4) over bar 3m and 58 molecules in the unit cell. The unit cell has a lattice parameter a = 11.911(1) angstrom at 8.3(2) GPa, which is a factor of root 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 a-manganese at ambient conditions. (C) 2014 AIP Publishing LLC.",

keywords = "X-RAY-DIFFRACTION, HIGH-PRESSURE, SOLID METHANE, SINGLE-CRYSTAL, ROOM-TEMPERATURE, DISSOCIATION, VOYAGER-2, INTERIORS, MANGANESE, CH4",

author = "Maynard-Casely, {H. E.} and Lundegaard, {L. F.} and I. Loa and McMahon, {M. I.} and E. Gregoryanz and Nelmes, {R. J.} and Loveday, {J. S.}",

year = "2014",

month = dec,

day = "21",

doi = "10.1063/1.4903813",

language = "English",

volume = "141",

journal = "The Journal of Chemical Physics",

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T1 - The crystal structure of methane B at 8 GPa-An alpha-Mn arrangement of molecules

AU - Maynard-Casely, H. E.

AU - Lundegaard, L. F.

AU - Loa, I.

AU - McMahon, M. I.

AU - Gregoryanz, E.

AU - Nelmes, R. J.

AU - Loveday, J. S.

PY - 2014/12/21

Y1 - 2014/12/21

N2 - 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 similar to 8 GPa. We find this substructure to be cubic with space group I (4) over bar 3m and 58 molecules in the unit cell. The unit cell has a lattice parameter a = 11.911(1) angstrom at 8.3(2) GPa, which is a factor of root 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 a-manganese at ambient conditions. (C) 2014 AIP Publishing LLC.

AB - 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 similar to 8 GPa. We find this substructure to be cubic with space group I (4) over bar 3m and 58 molecules in the unit cell. The unit cell has a lattice parameter a = 11.911(1) angstrom at 8.3(2) GPa, which is a factor of root 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 a-manganese at ambient conditions. (C) 2014 AIP Publishing LLC.

KW - X-RAY-DIFFRACTION

KW - HIGH-PRESSURE

KW - SOLID METHANE

KW - SINGLE-CRYSTAL

KW - ROOM-TEMPERATURE

KW - DISSOCIATION

KW - VOYAGER-2

KW - INTERIORS

KW - MANGANESE

KW - CH4

U2 - 10.1063/1.4903813

DO - 10.1063/1.4903813

M3 - Article

SN - 0021-9606

VL - 141

JO - The Journal of Chemical Physics

JF - The Journal of Chemical Physics

IS - 23

M1 - 234313

ER -

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

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