The crystal data and stability of calcite III at high pressures based on single-crystal X-ray experiments

• HAGIYA Kenji

  School of Science, University of Hyogo

• MATSUI Masanori

  School of Science, University of Hyogo

• KIMURA Yuhei

  School of Science, University of Hyogo

• AKAHAMA Yuichi

  School of Science, University of Hyogo

抄録

Single-crystal X-ray experiments have been performed for calcite, calcite II, and calcite III at 300 K and pressures up to 4.1 GPa. The volume decrease from calcite to calcite II is estimated to be 0.54 cm³/mol (1.5 %) at 1.5 GPa, which compares well with the value 0.48 cm³/mol in the calcite to calcite II transition at 1.4 GPa reported previously based on piston-cylinder volume-compression experiments. The crystal data of calcite III have been determined using single-crystal X-ray analyses at 300 K and pressures between 2.3 and 4.1 GPa. The calcite III crystal is found to be monoclinic with the space group either C2, Cm, or C2/m from the systematic absence of reflections, and with the refined cell parameters of a = 8.707(7), b = 9.315(6), c = 6.154(4) Å, and β = 115.18(2)° at 2.3 GPa. These crystal data of calcite III at 2.3 GPa yield a density of 2.94 g/cm³ for Z = 8, which is much less than the previously estimated densities, ranging from 3.11 to 3.28 g/cm³ at pressures from 1.9 to 2.9 GPa, using powder X-ray analyses based on orthorhombic structural models for calcite III, but is generally consistent with the reported data by the piston-cylinder experiments. Thus the present study reveals the density of calcite III is substantially less than that of aragonite (3.02 g/cm³ at 2.3 GPa), indicating that calcite III is metastable with respect to aragonite at high pressures.

収録刊行物

• Journal of Mineralogical and Petrological Sciences

  Journal of Mineralogical and Petrological Sciences 100 (1), 31-36, 2005

  一般社団法人　日本鉱物科学会

キーワード

• Calcite III
• High pressure
• Single-crystal X-ray analysis
• Stability
• Calcite polymorphs

詳細情報

• CRID: 1390001206546954624
• NII論文ID: 10013815963
• NII書誌ID: AA11460926
• DOI: 10.2465/jmps.100.31
• ISSN: 13493825
• ISSN: 13456296
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可