Elasticity of MgSiO3 in the ilmenite phase |
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| Authors: | Donald J Weidner Eiji Ito |
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| Institution: | Department of Earth and Space Sciences, State University of New York, Stony Brook, NY 11794 U.S.A.;Institute for Study of the Earth''s Interior, Okayama University, Misasa, Tottori-ken 682-02 Japan |
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| Abstract: | The single-crystal elastic moduli of the ilmenite phase of MgSiO3 have been determined from Brillouin spectroscopy. They are: C11 = 472, C12 = 168, C33 = 382, C13 = 70, C44 = 106, C14 = ?27, C66 = 152 and C25 = ?24 in GPa. These elastic properties are consistent with a structural mechanical model where the silicon octahedra are very stiff under compression and shear. This latter property yields an unexpectedly high shear modulus for the magnesium silicate ilmenite as compared with analogue compounds. The further transformation to perovskite will probably be associated with a significant increase in elastic properties since the strong silicon polyhedra form a structural network in this phase. The transformation of spinel and stishovite to ilmenite is associated with a slight density increase and a slight decrease in acoustic velocities. This transformation will probably not produce a seismic discontinuity even if it does occur in the Earth's mantle. |
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