HR: 15:10h
AN: MR53A-07    [Abstracts]
TI: Toward a self-consistent pressure scale: elastic moduli and equation of state of MgO by simultaneous x-ray density and Brillouin sound velocity measurements at high-pressure high-temperature conditions
AU: * Sinogeikin, S V
EM: ssinog@hpcat.aps.anl.gov
AF: HPCAT and Geophysical Lab, Carnegie Institution of Washington, 5251 Broad Branch Rd NW, Washington, DC 20015, United States
AU: Lakshtanov, D L
EM: lakshtan@uiuc.edu
AF: University of Illinois, Geology Dept, 1301 W Green St., Urbana, IL 61801, United States
AU: Prakapenka, V B
EM: prakapenka@cars.uchicago.edu
AF: GSECARS, University of Chicago, 9700 S. Cass Ave., Bldg 434A, Argonne, IL 60439, United States
AU: Sanchez-Valle, C
EM: carmen.sanchez@erdw.ethz.ch
AF: Institute for Mineralogy and Petrology, ETH Zurich, Clausiusstrasse 25 NW E83.2, Zurich, CH-8092, Switzerland
AU: Wang, J
EM: jwang11@uiuc.edu
AF: University of Illinois, Geology Dept, 1301 W Green St., Urbana, IL 61801, United States
AU: Chen, B
EM: binchen2@uiuc.edu
AF: University of Illinois, Geology Dept, 1301 W Green St., Urbana, IL 61801, United States
AU: Shen, G
EM: gshen@hpcat.aps.anl.gov
AF: HPCAT and Geophysical Lab, Carnegie Institution of Washington, 5251 Broad Branch Rd NW, Washington, DC 20015, United States
AU: Bass, J D
EM: jaybass@uiuc.edu
AF: University of Illinois, Geology Dept, 1301 W Green St., Urbana, IL 61801, United States
AB: Accurate phase diagrams and PVT equations of state (EOS) of materials strongly depend on the PVT calibrations of standard materials (e.g. MgO, NaCl, Au, Pt), which currently do not predict identical pressures at the same experimental conditions. MgO is commonly used as a pressure standard in a variety of high pressure and high- temperature experiments. Despite being one of the simplest and most studied materials, its accurate EOS is still uncertain, especially at high PT. The direct way of obtaining a self consistent pressure scale is by measuring acoustic velocities (Vp and Vs) and density simultaneously. Such P-V-T-Vp-Vs measurements allow one to determine the pressure directly, without resort to a separate calibration standard. Recently, as part of a major COMPRES initiative, we have constructed a Brillouin spectrometer at GSECARS, APS (13-BM-D) which allows accurate simultaneous sound velocity and lattice parameter measurements at high pressures and high temperatures. Such measurements were performed on single crystal MgO at simultaneously high pressures (up to 30 GPa) and high temperatures (up to 873K) in diamond cells with Ne or Ar as pressure medium. At each PT point we measured the unit cell parameters and the acoustic velocities of MgO in several crystallographic directions, and directly obtained all three single crystal elastic moduli, as well as isotropic adiabatic bulk (K_S) and shear (μ) moduli. Unit cell parameters of pressure medium (Ne, Ar) and additional pressure calibrants (Au, Pt, NaCl) were measured at each PT for cross calibration. The results of these experiments and implications for a self consistent P-V-T(-Vp-Vs) pressure scale will be presented and discussed.
DE: 3909 Elasticity and anelasticity
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3934 Optical, infrared, and Raman spectroscopy
DE: 3994 Instruments and techniques
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting