MgSiO3 perovskite has been assumed to be the dominant component of the Earth's lower mantle, although this phase alone cannot explain the discontinuity in seismic velocities observed 200–300 km above the core–mantle boundary (the D″ discontinuity) or the polarization anisotropy observed in the lowermost mantle1. Experimental and theoretical studies that have attempted to attribute these phenomena to a phase transition in the perovskite phase have tended to simply confirm the stability of the perovskite phase2,3,4,5,6. However, recent in situ X-ray diffraction measurements have revealed7 a transition to a ‘post-perovskite’ phase above 125 GPa and 2,500 K—conditions close to those at the D″ discontinuity. Here we show the results of first-principles calculations of the structure, stability and elasticity of both phases at zero temperature. We find that the post-perovskite phase becomes the stable phase above 98 GPa, and may be responsible for the observed seismic discontinuity and anisotropy in the lowermost mantle. Although our ground-state calculations of the unit cell do not include the effects of temperature and minor elements, they do provide a consistent explanation for a number of properties of the D″ layer.
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Poirier, J. P. Introduction to the Physics of the Earth's Interior (Cambridge Univ. Press, Cambridge, 2000)
Fiquet, G., Dewaele, A., Andrault, D., Kunz, M. & Le Bihan, T. Thermoelastic properties and crystal structure of MgSiO3 perovskite at lower mantle pressure and temperature conditions. Geophys. Res. Lett. 27, 21–24 (2000)
Andrault, D. Evaluation of (Mg, Fe) partitioning between silicate perovskite and magnesiowustite up to 120 GPa and 2300 K. J. Geophys. Res. 106, 2079–2087 (2001)
Stixrude, L. & Cohen, R. E. Stability of orthorhombic MgSiO3 perovskite in the Earth's lower mantle. Nature 364, 613–616 (1993)
Wentzcovitch, R. M., Ross, N. L. & Price, G. D. Ab initio study of MgSiO3 and CaSiO3 perovskites at lower-mantle pressures. Phys. Earth Planet. Inter. 90, 101–112 (1995)
Warren, M. C., Ackland, G. J., Karki, B. B. & Clark, S. J. Phase transitions in silicate perovskites from first principles. Mineral. Mag. 62, 585–598 (1998)
Murakami, M., Hirose, K., Kawamura, K., Sata, N. & Ohishi, Y. Post-perovskite phase transition in MgSiO3 . Science 304, 855–858 (2004)
Noel, H. & Padiou, J. Structure crystalline de FeUS3 . Acta Crystallogr. B 32, 1593–1595 (1976)
Narducci, A. A. & Ibers, J. A. The related compounds MThTe3(M = Mn, Mg) and ACuThSe3(A = K, Cs): Syntheses and characterization. Inorg. Chem. 39, 688–691 (2000)
Ijjaali, I., Mitchell, K., Huang, F. Q. & Ibers, J. A. Syntheses and characterization of the actinide manganese selenides ThMnSe3 and UMnSe3 . J. Solid State Chem. 177, 257–261 (2004)
Karki, B. B. et al. Structure and elasticity of MgO at high pressure. Am. Mineral. 82, 51–60 (1997)
Karki, B. B. et al. Elastic properties of orthorhombic MgSiO3 perovskite at lower mantle pressures. Am. Mineral. 82, 635–638 (1997)
Wysession, M. E., et al. in The Core-Mantle Boundary Region (eds Gurnis, M., Wysession, M. E., Knittle, E. & Buffett, B. A.) 273–297 (American Geophysical Union, Washington DC, 1998)
Sidorin, I., Gurnis, M. & Helmberger, D. V. Evidence for a ubiquitous seismic discontinuity at the base of the mantle. Science 286, 1326–1331 (1999)
Lay, T., Williams, Q., Garnero, E. J., Kellogg, L. & Wysession, M. E. in The Core-Mantle Boundary Region (eds Gurnis, M., Wysession, M. E., Knittle, E. & Buffett, B. A.) 299–318 (American Geophysical Union, Washington DC, 1998)
Panning, M. & Romanowicz, B. Inferences on flow at the base of Earth's mantle based on seismic anisotropy. Science 303, 351–353 (2004)
Montagner, J. P. & Nataf, H. C. A simple method for inverting the azimuthal anisotropy of surface waves. J. Geophys. Res. 91, 511–520 (1986)
Wentzcovitch, R. M., Karki, B. B., Karato, S. & Da Silva, C. R. S. High pressure elastic anisotropy of MgSiO3 perovskite and geophysical implications. Earth Planet. Sci. Lett. 164, 371–378 (1998)
Karato, S., Zhang, S. & Wenk, H. R. Superplasticity in Earth's lower mantle: evidence from seismic anisotropy and rock physics. Science 270, 458–461 (1995)
Masters, G. & Laske, G. in Earth's Deep Interior: Mineral Physics and Tomography from the Atomic to the Global Scale (eds Karato, S., Forte, A., Liebermann, R., Masters, G. & Stixrude, L.) 63–87 (American Geophysical Union, Washington DC, 2000)
Oganov, A. R., Brodholt, J. P. & Price, G. D. The elastic constants of MgSiO3 perovskite at pressures and temperatures of the Earth's mantle. Nature 411, 934–937 (2001)
Wentzcovitch, R. M., Karki, B. B., Cococcioni, M. & de Gironcoli, S. Thermoelastic properties of MgSiO3-perovskite: insights on the nature of the Earth's lower mantle. Phys. Rev. Lett. 92, 018501 (2004)
Murakami, M. Phase Transition of Lower Mantle Mineral and its Geophysical Implications Thesis, Tokyo Institute of Technology (2004)
Vanderbilt, D. Soft self-consistent pseudopotentials in a generalized eigenvalue formalism. Phys. Rev. B 41, 7892–7895 (1990)
Civalleri, B. & Harrison, N. M. New ultrasoft pseudopotentials for the study of silicates. Mol. Simulat. 28, 213–237 (2002)
Brodholt, J. P., Organov, A. R. & Price, G. D. Computational mineral physics and the physical properties of perovskite. Phil. Trans. R. Soc. Lond. A 360, 2507–2520 (2002)
Monkhorst, H. J. & Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B 13, 5188–5192 (1976)
Nielsen, O. H. & Martin, R. M. First principles calculation of stress. Phys. Rev. Lett. 50, 697–700 (1983)
Francis, G. P. & Payne, M. C. Finite basis set corrections to total energy pseudopotential calculations. J. Phys. Condens. Matter 2, 4395–4404 (1990)
Iitaka, T. & Ebisuzaki, T. First-principles calculation of elastic properties of solid argon at high pressures. Phys. Rev. B 65, 012103 (2002)
We thank S. Kaneshima for discussions, D.M. Bird for providing CASTEP codes, N.M. Harrison for pseudopotentials and the computer centres of RIKEN and NIG for access to the supercomputers. This work was also supported by JASRI/SPring-8 and IFREE/JAMSTEC.
The authors declare that they have no competing financial interests.
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Iitaka, T., Hirose, K., Kawamura, K. et al. The elasticity of the MgSiO3 post-perovskite phase in the Earth's lowermost mantle. Nature 430, 442–445 (2004). https://doi.org/10.1038/nature02702
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