HR: 0830h
AN: S21E-0366    [PDF]
TI: P-V-T Equation of State of Al-bearing Silicate Perovskite and its Implications for Mantle Composition Models
AU: * Fei, Y
EM: fei@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC 20015 United States
AU: Frank, M
EM: mfrank@niu.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC 20015 United States
AU: Frank, M
EM: mfrank@niu.edu
AF: Department of Geology and Environmental Geosciences, Northern Illinois University DeKalb, Dekalb, IL 01115 United States
AU: Mibe, K
EM: k.mibe@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC 20015 United States
AU: Shen, G
EM: shen@cars.uchicago.edu
AF: Center for Advanced Radiation Sources, Argonne National Lab, Buldg 434A, APS, 9700 S. Cass Ave, Argonne, IL 60439 United States
AU: Prakapenka, V
EM: Prakapenka@cars.uchicago.edu
AF: Center for Advanced Radiation Sources, Argonne National Lab, Buldg 434A, APS, 9700 S. Cass Ave, Argonne, IL 60439 United States
AB: Accurate measurements of P-V-T equations-of-state of mantle minerals are of fundamental importance for developing compositional and mineralogical models of the Earth's interior. Recent studies on Al-bearing silicate perovskites reported significantly different bulk moduli for Al-bearing perovskites. The discrepancy among the measured bulk moduli for the Al-bearing perovskite may be related to its defect chemistry and the substitution mechanism of Al in MgSiO$_{3}$ perovskite. In this study, we report new compression data on Al-bearing perovskites up to 65 GPa. The experiments were performed at the GSECARS 13-ID-D beamline (Advanced Photon Source), using monochromatic X-radiation and a CCD area detector. The Al-bearing perovskite starting materials were synthesized in a multi-anvil apparatus at 27 GPa and 2023 K. The synthesized perovsites mixed with Pt powder were compressed to 65 GPa in an externally-heated diamond anvil cell with neon or NaCl as the pressure medium. The samples were annealed in the stability field of perovskite by laser heating. The experiments were designed to examine the compression behavior of Al-bearing perovskites synthesized in the multi-anvil apparatus and re-synthesized by laser-heating in the diamond anvil cell. The results provide direct observations to address the effect of defect structure on the unit cell parameters at high pressures. In addition to the room-temperature compression data, we also obtained isothermal compression curves for Al-bearing perovskite at 700, 800, 900, and 1000 K. The data were used to establish a reliable thermal equation of state for Al-bearing silicate perovskite, which is critical for modeling the density profile of the lower mantle.
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3949 Thermal expansivity
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 8124 Earth's interior--composition and state (old 8105)
SC: Seismology [S]
MN: 2003 Fall Meeting