2008年
Postperovskite phase equilibria in the MgSiO3-Al 2O3 system
Proceedings of the National Academy of Sciences of the United States of America
- ,
- 巻
- 105
- 号
- 49
- 開始ページ
- 19160
- 終了ページ
- 19164
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1073/pnas.0805660105
We investigate high-P,T phase equilibria of the MgSiO3-Al 2O3 system by means of the density functional ab initio computation methods with multiconfiguration sampling. Being different from earlier studies based on the static substitution properties with no consideration of Rh2O3(II) phase, present calculations demonstrate that (i) dissolving Al2O3 tends to decrease the postperovskite transition pressure of MgSiO3 but the effect is not significant (≈-0.2 GPa/mol% Al2O3); (ii) Al 2O3 produces the narrow perovskite+postperovskite coexisting P,T area (≈1 GPa) for the pyrolitic concentration (x Al2O3 ≈ 6 mol%), which is sufficiently responsible to the deep-mantle D″ seismic discontinuity; (iii) the transition would be smeared (≈4 GPa) for the basaltic Al-rich composition (xAl2O3 ≈ 20 mol%), which is still seismically visible unless iron has significant effects; and last (iv) the perovskite structure spontaneously changes to the Rh2O3(II) with increasing the Al concentration involving small displacements of the Mg-site cations. © 2008 by The National Academy of Sciences of the USA.
- リンク情報
- ID情報
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- DOI : 10.1073/pnas.0805660105
- ISSN : 0027-8424
- ORCIDのPut Code : 49519629
- PubMed ID : 19036928
- SCOPUS ID : 58149149884