Chemistry and Physics of Minerals and Rocks/Volcanology

Hydrogen bond symmetrization and equation of state of phase D

  1. Anwar Hushur1,
  2. Murli H. Manghnani1,
  3. Joseph R. Smyth2,
  4. Quentin Williams3,
  5. Eric Hellebrand4,
  6. Dayana Lonappan1,
  7. Yu Ye5,
  8. Przemyslaw Dera6,
  9. Daniel J. Frost7

Article first published online: 9 JUN 2011

DOI: 10.1029/2010JB008087

Issue

Journal of Geophysical Research: Solid Earth (1978–2012)

Journal of Geophysical Research: Solid Earth (1978–2012)

Additional Information

How to Cite

Hushur, A., M. H. Manghnani, J. R. Smyth, Q. Williams, E. Hellebrand, D. Lonappan, Y. Ye, P. Dera, and D. J. Frost (2011), Hydrogen bond symmetrization and equation of state of phase D, J. Geophys. Res., 116, B06203, doi:10.1029/2010JB008087.

Author Information

  1. 1

    Hawai'i Institute of Geophysics, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA

  2. 2

    Department of Geological Sciences, University of Colorado at Boulder, Boulder, Colorado, USA

  3. 3

    Department of Earth Sciences, University of California, Santa Cruz, California, USA

  4. 4

    School of Ocean and Earth Science and Technology, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA

  5. 5

    Department of Physics, University of Colorado at Boulder, Boulder, Colorado, USA

  6. 6

    Argonne National Laboratory, Center for Advanced Radiation Sources, University of Chicago, Argonne, Illinois, USA

  7. 7

    Bayerisches Geoinstitut, Universitaet Bayreuth, Bayreuth, Germany

Publication History

  1. Issue published online: 9 JUN 2011
  2. Article first published online: 9 JUN 2011
  3. Manuscript Accepted: 17 MAR 2011
  4. Manuscript Revised: 8 MAR 2011
  5. Manuscript Received: 5 NOV 2010

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Keywords:

  • DHMS;
  • hydrogen bond;
  • equation of state;
  • phase D;
  • hydrous mineral;
  • XRD

[1] We have synthesized phase D at 24 GPa and at temperatures of 1250–1100°C in a multianvil press under conditions of high silica activity. The compressibility of this high-silica-activity phase D (Mg1.0Si1.7H3.0O6) has been measured up to 55.8 GPa at ambient temperature by powder X-ray diffraction. The volume (V) decreases smoothly with increasing pressure up to 40 GPa, consistent with the results reported in earlier studies. However, a kink is observed in the trend of V versus pressure above ∼40 GPa, reflecting a change in the compression behavior. The data to 30 GPa fit well to a third-order Birch-Murnaghan equation of state (EoS), yielding Vo = 85.1 ± 0.2 Å3; Ko = 167.9 ± 8.6 GPa; and K′o = 4.3 ± 0.5, similar to results for Fe-Al-free phase D reported by Frost and Fei (1999). However, these parameters are larger than those reported for Fe-Al-bearing phase D and for Fe-Al-free phase D. The abnormal volume change in this study may be attributed to the reported hydrogen bond symmetrization in phase D. Fitting a third-order Birch-Murnaghan EoS to the data below 30 GPa yields a bulk modulus Ko = 173 (2) GPa for the hydrogen-off-centered (HOC) phase and Ko = 212 (15) GPa for the data above 40 GPa for the hydrogen-centered (HC) phase, assuming K′o is 4. The calculated bulk modulus Ko of the HC phase is 18% larger than the bulk modulus Ko of the HOC phase.

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