The baddeleyite-type high pressure phase of Ca(OH)2

M. Kunz, Kurt Leinenweber, J. B. Parise, T. C. Wu, W. A. Bassett, K. Brister, D. J. Weidner, M. T. Vaughan, Y. Wang

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

A phase transition from Ca(OH)2 I (portlandite) to Ca(OH)2 II at high pressure and temperature has been confirmed, using in situ x-ray diffraction in a multianvil high pressure device (DIA). The structure was determined at 9.5 GPa and room temperature from data collected after heating the sample at 300°C at 7.2 GPa in a diamond anvil cell. Both the Le Bail fit and preliminary Rietveld refinement suggest that the new phase, which reverts to Ca(OH)2 I during pressure release, has a structure related to that of baddeleyite (ZrO1); it is monoclinic (P21/c) with a = 4.887(2), b = 5.834(2), c = 5.587(2), β = 99.74(2)°. The coordination number of Ca increases from six to seven (5 + 2) across the transition. At 500°C, the phase boundary is bracketed at 5.7 ± 0.4 GPa by reversal experiments performed in the DIA.

Original languageEnglish (US)
Pages (from-to)311-319
Number of pages9
JournalHigh Pressure Research
Volume14
Issue number4-5
StatePublished - Dec 1 1996

Keywords

  • Ca(OH)
  • High pressure
  • Phase transition
  • X-ray diffraction

ASJC Scopus subject areas

  • Condensed Matter Physics

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    Kunz, M., Leinenweber, K., Parise, J. B., Wu, T. C., Bassett, W. A., Brister, K., Weidner, D. J., Vaughan, M. T., & Wang, Y. (1996). The baddeleyite-type high pressure phase of Ca(OH)2. High Pressure Research, 14(4-5), 311-319.