Phase transition in MgSiO3 perovskite in the earth's lower mantle

Taku Tsuchiya; Jun Tsuchiya; Koichiro Umemoto; Renata M. Wentzcovitch

doi:10.1016/j.epsl.2004.05.017

Phase transition in MgSiO₃ perovskite in the earth's lower mantle

Taku Tsuchiya, Jun Tsuchiya, Koichiro Umemoto, Renata M. Wentzcovitch

Chemical Engineering and Materials Science

Research output: Contribution to journal › Article › peer-review

506 Scopus citations

Abstract

A new polymorph of MgSiO₃ more stable than the Pbnm -perovskite phase has been identified by first-principles computations. It has the CaIrO₃ structure with Cmcm symmetry and consists of SiO₃ layers intercalated by eightfold-coordinated Mg ions. High-temperature calculations within the quasiharmonic approximation give a volume change of ∼1.5% and a Clapeyron slope of ∼7.5±0.3 MPa/K at ∼2750 K and ∼125 GPa. These pressure-temperature (P-T) conditions are close to those in which a phase transition in MgSiO₃-perovskite has been observed by in situ angle dispersive X-ray diffraction measurements. This transition appears to be associated with the D″ discontinuity.

Original language	English (US)
Pages (from-to)	241-248
Number of pages	8
Journal	Earth and Planetary Science Letters
Volume	224
Issue number	3-4
DOIs	https://doi.org/10.1016/j.epsl.2004.05.017
State	Published - Aug 15 2004

Bibliographical note

Funding Information:
The authors thank K. Hirose and M. Murakami for supplying experimental data and D. Yuen, M. Akaogi, K. Fujino, E. Ito, and K. Takemura for helpful comments. This research was supported by NSF/EAR 0135533 and 0230319. T.T. and J.T. acknowledge the Japan Society for the Promotion of Science (JSPS) for research fellowships. [SK]

Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.

Keywords

Core-mantle boundary
D″ layer
First principle
MgSiO
Post-perovskite

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title = "Phase transition in MgSiO3 perovskite in the earth's lower mantle",

abstract = "A new polymorph of MgSiO3 more stable than the Pbnm -perovskite phase has been identified by first-principles computations. It has the CaIrO3 structure with Cmcm symmetry and consists of SiO3 layers intercalated by eightfold-coordinated Mg ions. High-temperature calculations within the quasiharmonic approximation give a volume change of ∼1.5% and a Clapeyron slope of ∼7.5±0.3 MPa/K at ∼2750 K and ∼125 GPa. These pressure-temperature (P-T) conditions are close to those in which a phase transition in MgSiO3-perovskite has been observed by in situ angle dispersive X-ray diffraction measurements. This transition appears to be associated with the D″ discontinuity.",

keywords = "Core-mantle boundary, D″ layer, First principle, MgSiO, Post-perovskite",

author = "Taku Tsuchiya and Jun Tsuchiya and Koichiro Umemoto and Wentzcovitch, {Renata M.}",

note = "Funding Information: The authors thank K. Hirose and M. Murakami for supplying experimental data and D. Yuen, M. Akaogi, K. Fujino, E. Ito, and K. Takemura for helpful comments. This research was supported by NSF/EAR 0135533 and 0230319. T.T. and J.T. acknowledge the Japan Society for the Promotion of Science (JSPS) for research fellowships. [SK] Copyright: Copyright 2011 Elsevier B.V., All rights reserved.",

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N1 - Funding Information: The authors thank K. Hirose and M. Murakami for supplying experimental data and D. Yuen, M. Akaogi, K. Fujino, E. Ito, and K. Takemura for helpful comments. This research was supported by NSF/EAR 0135533 and 0230319. T.T. and J.T. acknowledge the Japan Society for the Promotion of Science (JSPS) for research fellowships. [SK] Copyright: Copyright 2011 Elsevier B.V., All rights reserved.

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N2 - A new polymorph of MgSiO3 more stable than the Pbnm -perovskite phase has been identified by first-principles computations. It has the CaIrO3 structure with Cmcm symmetry and consists of SiO3 layers intercalated by eightfold-coordinated Mg ions. High-temperature calculations within the quasiharmonic approximation give a volume change of ∼1.5% and a Clapeyron slope of ∼7.5±0.3 MPa/K at ∼2750 K and ∼125 GPa. These pressure-temperature (P-T) conditions are close to those in which a phase transition in MgSiO3-perovskite has been observed by in situ angle dispersive X-ray diffraction measurements. This transition appears to be associated with the D″ discontinuity.

AB - A new polymorph of MgSiO3 more stable than the Pbnm -perovskite phase has been identified by first-principles computations. It has the CaIrO3 structure with Cmcm symmetry and consists of SiO3 layers intercalated by eightfold-coordinated Mg ions. High-temperature calculations within the quasiharmonic approximation give a volume change of ∼1.5% and a Clapeyron slope of ∼7.5±0.3 MPa/K at ∼2750 K and ∼125 GPa. These pressure-temperature (P-T) conditions are close to those in which a phase transition in MgSiO3-perovskite has been observed by in situ angle dispersive X-ray diffraction measurements. This transition appears to be associated with the D″ discontinuity.

KW - Core-mantle boundary

KW - D″ layer

KW - First principle

KW - MgSiO

KW - Post-perovskite

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