HR: 1340h
AN: MR23A-1024    [Abstracts]
TI: Phase Stability and Melting Temperature of Epsilon Oxygen at Half a Megabar
AU: * Benedetti, L
EM: benedetti3@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550, United States
AU: Mezouar, M
EM: mezouar@esrf.fr
AF: European Synchrotron Radiation Facility, Polygone Scientifique Louis Néel 6, rue Jules Horowitz, Grenoble, 38000, France
AU: Antonangeli, D
EM: antonangeli3@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550, United States
AU: Aracne, C
EM: aracneruddle1@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550, United States
AU: Farber, D L
EM: farber2@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550, United States
AB: Measurements of the chemistry and physics of the pure endmembers of the C-O-H-N-S system are important building blocks in the study of planetary ices. To that end, we performed x-ray diffraction measurements on pure oxygen using the laser-heated diamond anvil cell. Using a novel experimental setup and a combined interpretation of the diffraction patterns in conjunction with spectroradiometric observations, the temperature and pressure stability field of the ε -phase has been studied. We also present measurements of the melting temperature of oxygen at 47 and 55 GPa, pressures more than twice as high as previously achieved. The ensemble of our experimental evidence highlights the remarkable thermodynamic stability of the O₈ cluster structure with respect to lower pressure molecular arrangements and points to non-magnetic ordering as one of the main reasons for that.
DE: 3924 High-pressure behavior
DE: 3934 Optical, infrared, and Raman spectroscopy
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
DE: 5724 Interiors (8147)
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting