HR: 1340h
AN: MR23C-1529    [Abstracts]
TI: First-Principles Study of Elasticity and Decomposition of Phase D
AU: * LI, L
EM: lilli@ic.sunysb.edu
AF: Stony Brook University, Dept of Geosciences Stony Brook University, Stony Brook, NY 11794, United States
AU: Kiefer, B
EM: bkiefer@physics.nmsu.edu
AF: New Mexico State University, Department of Physics New Mexico State University, Las Cruces, NM 88003, United States
AB: We have investigated the compressional behavior and elastic properties of phase D (MgSi2H2O6) for pressures up to 60 GPa using first-principles calculations. The calculated bulk modulus K0 is 156.2 GPa; shear modulus G0 is 122.6GPa; p wave velocity Vp is 9.6 Km/s; shear wave velocity Vs is 5.9 Km/s. Their pressure derivative dK/dP and dG/dP are 4.88 and 2.29; dVp/dP and dVs/dP are 0.083 and 0.041. At 0 GPa, Phase D has an elastic anisotropy of 1.21 and 1.19 percent, for compressional and shear waves, respectively, which decreases to 1.03 and 1.07 percent at 45 GPa, our alculated decomposition pressure of phase D. We find that phase D is most likely decomposes by absorbing MgO to form MgSiO3 perovskite and H2O at 45 GPa; we also find that it is unlikely that phase D produces free SiO2 upon decomposition. The decomposition of phase D causes a 1 percent increase in compressional velocity and the shear wave velocity remains unaffected.
DE: 3909 Elasticity and anelasticity
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3999 General or miscellaneous
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting