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GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L03306, doi:10.1029/2005GL024955, 2006

Crystal structure and equation of state of MgSiO3 perovskite

C. B. Vanpeteghem

Crystallography Laboratory, Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA


J. Zhao

Crystallography Laboratory, Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA


R. J. Angel

Crystallography Laboratory, Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA


N. L. Ross

Crystallography Laboratory, Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA


N. Bolfan-Casanova

Laboratoire Magmas et Volcans, Université Clermont-Ferrand, CNRS, Clermont-Ferrand, France


Abstract

We have re-examined the crystal structure and equation of state of MgSiO3 perovskite by single-crystal X-ray diffraction up to 10 GPa. We have determined an isothermal bulk modulus K0 = 253(1) GPa with K′0 = 4, which is in excellent agreement with the adiabatic bulk moduli reported in recent studies by Brillouin spectroscopy and ultrasonic interferometry. We confirm that the compressibility of perovskite is anisotropic with the b-axis being the least compressible direction. On compression, the bond lengths and angles on Mg-site and Si-site decrease continuously, indicating that the structure gets more distorted as pressure increases. This is supported by a general model for perovskites that predicts that the octahedra become more tilted at lower mantle pressures.

Received 14 October 2005; accepted 28 December 2005; published 4 February 2006.

Index Terms: 1042 Geochemistry: Mineral and crystal chemistry (3620); 3620 Mineralogy and Petrology: Mineral and crystal chemistry (1042); 3919 Mineral Physics: Equations of state; 3924 Mineral Physics: High-pressure behavior.

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Citation: Vanpeteghem, C. B., J. Zhao, R. J. Angel, N. L. Ross, and N. Bolfan-Casanova (2006), Crystal structure and equation of state of MgSiO3 perovskite, Geophys. Res. Lett., 33, L03306, doi:10.1029/2005GL024955.