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Title: Structure and stability of solid Xe(H{sub 2}){sub 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(H{sub 2}){sub 8} crystallizes in a P3{sup -}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{sup -}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:H{sub 2} stoichiometry fixed at 1:8. 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. Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015-1305 (United States)
  2. GSECARS, Advanced Photon Source, University of Chicago, Argonne, Illinois 60439 (United States)
  3. HPCAT, Advanced Photon Source, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States)
Publication Date:
OSTI Identifier:
22415510
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 10; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ATOMS; HYDROGEN; MIXTURES; MONOCRYSTALS; PHASE STABILITY; PHASE STUDIES; PRESSURE DEPENDENCE; RAMAN SPECTROSCOPY; SOLIDS; STOICHIOMETRY; TEMPERATURE DEPENDENCE; VAN DER WAALS FORCES; XENON; X-RAY DIFFRACTION