B1-B2 transition in CaO and possibility of CaSiO3-perovskite decomposition under high pressure.

• YAMANAKA Takamitsu

  Department of Earth and Space Science, Graduate School of Science

• KITTAKA Kouichi

  Department of Earth and Space Science, Graduate School of Science

• NAGAI Takaya

  Department of Earth and Space Science, Graduate School of Science

抄録

X-ray powder diffraction measurements of CaO at high pressure and temperature have been performed using a lever-spring type diamond anvil cell equipped with an external ring heater. The B1 structure transformed into B2 at about 61.2∼63.2 GPa at room temperature during the compression, and the back transformation from the B2 to B1 structure was found at 59.8 GPa during the depression. The equation of states of both the B1 and B2 structures are obtained by Birch-Murnaghan equation. Because B2 structure of CaO is unstable at ambient conditions, the bulk modulus of the B2 structure at high temperature was firstly determined from the P-V-T curve. The B1-B2 transition pressure slightly lowers from 58.8 GPa at 295 K to 53.1 GPa at 685 K, resulting in dP/dT<0. A back transformation from the B2 to B1 structure by depression shows a large hysteresis. The B1-B2 transition highly depends on pressure rather than temperature. Only from the volumes of the CaSiO₃ components, CaSiO₃ perovskite possibly decomposes to SiO₂ (CaCl₂ type) and CaO (B2) in the pressure and temperature range of the lower mantle.

収録刊行物

• Journal of Mineralogical and Petrological Sciences

  Journal of Mineralogical and Petrological Sciences 97 (4), 144-152, 2002

  一般社団法人　日本鉱物科学会

キーワード

• Geology
• Geophysics

詳細情報

• CRID: 1390282681523463936
• NII論文ID: 130000254862
• DOI: 10.2465/jmps.97.144
• 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