論文

査読有り
2015年

First-principles investigation of hydrous post-perovskite

Physics of the Earth and Planetary Interiors
  • Joshua P. Townsend
  • ,
  • Jun Tsuchiya
  • ,
  • Craig R. Bina
  • ,
  • Steven D. Jacobsen

244
開始ページ
42
終了ページ
48
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1016/j.pepi.2015.03.010

A stable, hydrogen-defect structure of post-perovskite (hy-ppv, Mg1-xSiH2xO3) has been determined by first-principles calculations of the vibrational and elastic properties up to 150GPa. Among three potential hy-ppv structures analyzed, one was found to be stable at pressures relevant to the lower-mantle D<sup>″</sup> region. Hydrogen has a pronounced effect on the elastic properties of post-perovskite due to magnesium defects associated with hydration, including a reduction of the zero-pressure bulk (K<inf>0</inf>) and shear (G<inf>0</inf>) moduli by 5% and 8%, respectively, for a structure containing ~1wt.% H<inf>2</inf>O. However, with increasing pressure the moduli of hy-ppv increase significantly relative to ppv, resulting in a structure that is only 1% slower in bulk compressional velocity and 2.5% slower in shear-wave velocity than ppv at 120GPa. In contrast, the reduction of certain anisotropic elastic constants (C<inf>ij</inf>) in hy-ppv increases with pressure (notably, C<inf>55</inf>, C<inf>66</inf>, and C<inf>23</inf>), indicating that hydration generally increases elastic anisotropy in hy-ppv at D<sup>″</sup> pressures. Calculated infrared absorption spectra show two O-H stretching bands at ~3500cm<sup>-1</sup> that shift with pressure to lower wavenumber by about 2cm<sup>-1</sup>/GPa. At 120GPa the hydrogen bonds in hy-ppv are still asymmetric. The stability of a hy-ppv structure containing 1-2wt.% H<inf>2</inf>O at D<sup>″</sup> pressures implies that post-perovskite may be a host for recycled or primordial hydrogen near the Earth's core-mantle boundary.

リンク情報
DOI
https://doi.org/10.1016/j.pepi.2015.03.010
Scopus Url
http://www.scopus.com/inward/record.url?eid=2-s2.0-84930092243&partnerID=MN8TOARS
URL
http://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84930092243&origin=inward
ID情報
  • DOI : 10.1016/j.pepi.2015.03.010
  • ISSN : 0031-9201
  • ORCIDのPut Code : 49519618
  • SCOPUS ID : 84930092243

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