Space group and hydrogen sites of δ-AlOOH and implications for a hypothetical high-pressure form of Mg(OH)2

Y. Kudoh, T. Kuribayashi, A. Suzuki, Eiji Otani, T. Kamada

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19 Citations (Scopus)

Abstract

The space group and hydrogen positions of δ-(Al0.84 Mg0.07Si0.09)OOH are investigated using a single crystal synthesized using a multi-anvil apparatus under conditions of 1000 °C and 21 GPa. The space group determined by single-crystal X-ray diffraction is to Pnn 2, with unit-cell parameters of a = 4.6975(8) Å, b = 4.2060(6) Å, c = 2.8327(4) Å, and V = 55.97(1) Å3. Partial occupancy of the Al site by Mg and Si suggests the possibility of a limited solid solution between δ-AlOOH, stishovite, and a hypothetical CaCl2-type Mg(OH)2 that is 16% denser than brucite. Difference-Fourier maps reveal two small but significant Fourier peaks attributable to hydrogen atoms. Atomic distances and angles around the first peak indicate a hydrogen bond with O⋯O distances of 2.511 Å, while those around the second peak are suggestive of a bifurcated hydrogen bond with O⋯O distances of 2.743 and 2.743 Å.

Original languageEnglish
Pages (from-to)360-364
Number of pages5
JournalPhysics and Chemistry of Minerals
Volume31
Issue number6
DOIs
Publication statusPublished - 2004 Jul 1

Keywords

  • High-pressure form of Mg(OH)
  • Hydrogen sites
  • Space group
  • δ-AlOOH

ASJC Scopus subject areas

  • Materials Science(all)
  • Geochemistry and Petrology

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