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Title: Structure and stability of solid Xe(H2)n

Mixtures of xenon and molecular hydrogen form a series of hexagonal, van der Waals compounds at high pressures and at 300 K. Synchrotron, x-ray, single crystal diffraction studies reveal that below 7.5 GPa, Xe(H2)8 crystallizes in a P3¯m1 structure that displays pressure-induced occupancy changes of two pairs of xenon atoms located on the 2c and 2d sites (while the third pair on yet another 2c site remains fully occupied). The occupancy becomes 1 at the P3¯m1 to R3 transition and all the xenon atoms occupy the 3d sites in the high-pressure structure. These pressure-induced changes in occupancy coincide with volume changes that maintain the average Xe:H2 stoichiometry fixed at 1:8. Furthermore, the synchrotron x-ray diffraction and Raman measurements show that this unique hydrogen-bearing compound that can be synthesized at 4.2 GPa and 300 K, quenched at low temperatures to atmospheric pressure, and retained up to 90 K on subsequent warming.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Carnegie Institution of Washington, Washington, D.C. (United States)
  2. Univ. of Chicago, Argonne, IL (United States)
  3. Carnegie Institution of Washington, Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
NA0002006; AC02-06CH11357; FG02-06ER46280; FG02-99ER45775; NA-0002006; NA0001974
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 142; Journal Issue: 10; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Carnegie Institution of Washington, Washington, D.C. (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1335840
Alternate Identifier(s):
OSTI ID: 1228238