HR: 16:30h
AN: T54A-03 INVITED     [Abstracts]
TI: Elastic anisotropy and texture of iron at high pressure
AU: * Mao, W L
EM: wmao@uchicago.edu
AF: University of Chicago, Department of the Geophysical Sciences 5734 S. Ellis Avenue, Chicago, IL 60637 United States
AU: * Mao, W L
EM: wmao@uchicago.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington 5251 Broad Branch Road, Washington, DC 20015 United States
AU: Wenk, H
EM: wenk@seismo.berkeley.edu
AF: University of California, Berkeley, Department of Earth and Planetary Science McCone Hall, Berkeley, CA 94720 United States
AU: Tommaseo, C
EM: tommaseo@eps.berkeley.edu
AF: University of California, Berkeley, Department of Earth and Planetary Science McCone Hall, Berkeley, CA 94720 United States
AU: Baron, A
EM: baron@spring8.or.jp
AF: SPring-8/JASRI, 1-1-1 Kouto, Mikazuki-cho , Sayo-gun, Hyogo, 679-5198 Japan
AU: Chow, P
EM: pchow@hpcat.aps.anl.gov
AF: HPCAT, Advanced Photon Source Argonne National Laboratory 9700 South Cass Avenue, Argonne, IL 60439 United States
AU: Heinz, D L
EM: heinz@geosci.uchicago.edu
AF: University of Chicago, Department of the Geophysical Sciences 5734 S. Ellis Avenue, Chicago, IL 60637 United States
AU: Heinz, D L
EM: heinz@geosci.uchicago.edu
AF: University of Chicago, James Franck Institute 5640 S. Ellis Avenue, Chicago, IL 60637 United States
AU: Struzhkin, V V
EM: struzhkin@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington 5251 Broad Branch Road, Washington, DC 20015 United States
AU: Hemley, R J
EM: hemley@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington 5251 Broad Branch Road, Washington, DC 20015 United States
AU: Mao, H
EM: mao@gl.ciw.edu
AF: University of Chicago, Department of the Geophysical Sciences 5734 S. Ellis Avenue, Chicago, IL 60637 United States
AU: Mao, H
EM: mao@gl.ciw.edu
AF: HPCAT, Advanced Photon Source Argonne National Laboratory 9700 South Cass Avenue, Argonne, IL 60439 United States
AU: Mao, H
EM: mao@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington 5251 Broad Branch Road, Washington, DC 20015 United States
AU: Mao, H
EM: mao@gl.ciw.edu
AF: University of Chicago, James Franck Institute 5640 S. Ellis Avenue, Chicago, IL 60637 United States
AB: Understanding the elastic anisotropy and texture of relevant core materials at high pressure is crucial to interpreting seismic observations of inner core anisotropy. Conventional measurements of elastic moduli require large, single crystals which have not yet been synthesized for hcp iron. However, with the development of new synchrotron techniques, we are able to get equivalent information via the combination of texture studies and directional phonon measurements. Radial diffraction conducted at Sector 16 of the Advanced Photon Source, Argonne National Laboratory, was used to determine the preferred orientation in polycrystalline iron samples under the presence of differential stress. Here a diamond anvil cell with a large ($150\deg$) side opening and x-ray transparent gasket (e.g. beryllium or amorphous boron) allowed access to the complete strain field. The intensity variations around the resulting Debye-Scherrer rings for different reflections were used to determine pole figures. We then conducted inelastic x-ray studies at BL35XU of SPring-8 on the same, textured iron samples at high pressure and measured phonon energy as a function of momentum transfer. The initial slope of that curve was used to calculate the acoustic velocities, allowing determination of elastic anisotropy in a well-characterized textured hcp iron sample.
DE: 3900 MINERAL PHYSICS
DE: 3909 Elasticity and anelasticity
DE: 3924 High-pressure behavior
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting