Elasticity of (Mg, Fe)(Si, Al)O-3-perovskite at high pressure

Li, L. and Brodholt, J.P. and Stackhouse, S. and Weidner, D.J. and Alfredsson, M. and Price, G.D. (2005) Elasticity of (Mg, Fe)(Si, Al)O-3-perovskite at high pressure. Earth and Planetary Science Letters, 240 (2). pp. 529-536. ISSN 0012-821X. (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/10.1016/j.epsl.2005.09.030

Abstract

The most abundant mineral on Earth has a perovskite crystal structure and a chemistry that is dominated by MgSiO3 with the next most abundant cations probably being aluminum and ferric iron. The dearth of experimental elasticity data for this chemically complex mineral limits our ability to calculate model seismic velocities for the lower mantle. We have calculated the single crystal elastic moduli (c(ij)) for (Mg, Fe3+)(Si, Al)O-3 perovskite using density functional theory in order to investigate the effect of chemical variations and spin state transitions of the Fe3+ ions. Considering the favored coupled substitution of Mg2+-Si4+ by Fe3+-Al3+, we find that the effect of ferric iron on seismic properties is comparable with the same amount of ferrous iron. Ferric iron lowers the elastic moduli relative to the Al charge-coupled substitution. Substitution of Fe3+ for Al3+, giving rise to an Fe/Mg ratio of 6%, causes 1.8% lower longitudinal velocity and 2.5% lower shear velocity at ambient pressure and 1.1% lower longitudinal velocity and 1.8% lower shear velocity at 142 GPa. The spin state of the iron for this composition has a relatively small effect (<0.5% variation) on both bulk modulus and shear modulus. (C) 2005 Elsevier B.V. All rights reserved.

Item Type: Article
Additional information: ISI Document Delivery No.: 000NX Times Cited: 8 Cited Reference Count: 47
Uncontrolled keywords: elasticity perovskite ferric iron density functional theory MAGNESIUM-SILICATE PEROVSKITE EARTHS LOWER MANTLE AUGMENTED-WAVE METHOD EQUATION-OF-STATE MGSIO3 PEROVSKITE (MG,FE)SIO3 PEROVSKITE AB-INITIO THERMAL-EXPANSION CRYSTAL-STRUCTURE SINGLE-CRYSTAL
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Physical Sciences > Functional Materials Group
Depositing User: Maria Alfredsson
Date Deposited: 03 Sep 2008 14:18
Last Modified: 14 Jan 2010 14:17
Resource URI: http://kar.kent.ac.uk/id/eprint/4782 (The current URI for this page, for reference purposes)
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