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Licensed Unlicensed Requires Authentication Published by De Gruyter March 28, 2015

First-principles study of hydrogen bond symmetrization of phase D under high pressure

  • Jun Tsuchiya EMAIL logo , Taku Tsuchiya and Shinji Tsuneyuki
From the journal American Mineralogist


We have investigated the physical and structural properties of phase D (MgSi2O6H2) at high pressure by means of a first-principles calculation method. Phase D is important as a dense hydrous magnesium silicate with high stability under pressure, and as one of the most likely candidates for a water reservoir in the Earth’s lower mantle. The calculated compression behavior of phase D is in very good agreement with experimental results. We found a distinct but continuous change from asymmetric to symmetric hydrogen bonding in phase D at 40 GPa. This pressure-induced hydrogen bond symmetrization has a significant effect on the compression behavior of phase D. The bulk modulus increases by about 20% with this structural change. This behavior of pressure-induced hydrogen bond symmetrization is very similar to that previously reported by us for δ-AlOOH. The transition is reversible and second-order, and thus the high-pressure state is probably unquenchable.

Received: 2004-2-20
Accepted: 2004-6-28
Published Online: 2015-3-28
Published in Print: 2005-1-1

© 2015 by Walter de Gruyter Berlin/Boston

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