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Transformations in methane hydrates

delete2000-11-21
delete179
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OA
AI
I
I‐Ming Chou *
A
Anurag Sharma
R
Robert C. Burruss
J
Jinfu Shu
H
Ho‐kwang Mao
R
Russell J. Hemley
A
Alexander F. Goncharov
L
Laura A. Stern
S
S. H. Kirby
DOI:10.1073/pnas.250466497delete
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Abstract

Abstract

En 中文
Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure Il methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) Angstrom and volume V = 5051.3(13) Angstrom (3); structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A, c = 9.992(3) Angstrom, and V = 1241.9(5) Angstrom (3). The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure Ii phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.
Keywords:
HIGH-PRESSURE PHASE
DIAMOND-ANVIL CELL
X-RAY-DIFFRACTION
CLATHRATE HYDRATE
ICE
SYSTEM
GAS
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Journal

P
Proceedings of the National Academy of Sciences of the United States of America
IF:
9.1
Papers:
10.8W
Citations:
73.5W

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