Study of the structure and elastisity of iron-alloys at high pressure and high tempreture

2013 Fiscal Year Final Research Report

• Project/Area Number: 23740396
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Petrology/Mineralogy/Science of ore deposit
• Research Institution: Ehime University
• Principal Investigator: KUWAYAMA Yasuhiro 愛媛大学, 地球深部ダイナミクス研究センター, 助教 (00554015)
• Project Period (FY): 2011 – 2013
• Keywords: 地球中心核 / 相平衡 / 高圧高温実験

Research Abstract

I performed in situ x-ray diffraction studies on Fe and Fe alloys using a laser heated diamond anvil cell. The results show the wide stability field of the hcp phases of Fe and Fe-10 wt% Ni alloy up to 320 GPa and 4,500 K and their small temperature dependences of the c/a ratio of less than 1x10-6 K-1. I also performed ab initio molecular dynamics simulations to calculate the elastic properties of Fe and Fe alloys. The results indicats the elastic isotropy of hcp Fe and Fe-Ni alloys at the Earth's core condition, but the addition of light elements increases the elastic anisotropy of iron alloys. The high pressure and temperature experiments on Fe-Si alloy using a laser heated diamond anvil cell indicate that the more than 9.9 wt% Si can be soluble in the solid hcp Fe alloy at the conditions of the Earth's inner core. These results show that the Fe-Si alloy in the inner core would explain the seismic anisotropy in the inner core.

Research Products

• [Journal Article] Melting temperatures of H2O up to 72 GPa measured in a diamond anvil cell using CO2 laser heating technique (2014)
  • Author(s): Kimura, T., Kuwayama, Y., Yagi, T
  • Journal Title: Journal of Chemical Physics Volume: 140 Pages: 74501
• [Journal Article] Highly conductive iron-rich (Mg,Fe)O magnesiowustite and its stability in the Earth's lower mantle (2014)
  • Author(s): Ohta, K., Fujino, K., Kuwayama, Y., Kondo, T., Shimizu, K., Ohishi, Y
  • Journal Title: Journal of Geophysical Research : Solid Earth
  • DOI: 10.1002/2014JB010972
  • Peer Reviewed
• [Journal Article] Spin transition, substitution, and partitioning of iron in lower mantle minerals (2014)
  • Author(s): Fujino, K., Nishio-Hamane, D., Nagai, T., Seto, Y., Kuwayama, Y., Whitaker, M., Ohfuji, H., Shinmei, T., Irifune, T
  • Journal Title: Physics of the Earth and Planetary Interiors Volume: 228 Pages: 186-191
  • Peer Reviewed
• [Journal Article] Spin transition and substitution of Fe3+ in Al-bearing post-Mg-perovskite (2013)
  • Author(s): Fujino, K., Nishio-Hamane, D., Kuwayama, Y., Sata, N., Murakami, S., Whitaker, M., Shinozaki, A., Ohfuji, H., Kojima, Y., Irifune, T., Hiraoka, N., Ishii, H., Tsuei, K. -D
  • Journal Title: Physics of the Earth and Planetary Interiors Volume: 217 Pages: 31-35
  • Peer Reviewed
• [Journal Article] P-V-T equation of state of MgSiO_3 perovskite based on the MgO pressure scale : A comprehensive reference for mineralogy of the lower mantle (2012)
  • Author(s): Tange, Y., Kuwayama, Y., Irifune, T., Funakoshi, K.-I., Ohishi, Y
  • Journal Title: Journal of Geophysical Research B : Solid Earth Volume: 117 Pages: B06201
  • Peer Reviewed
• [Journal Article] Pressure-induced structural evolution of pyrite-type SiO_2 (2011)
  • Author(s): Kuwayama, Y., Hirose, K., Sata, N., Ohishi, Y
  • Journal Title: Physics and Chemistry of Minerals Volume: 38 Pages: 591-597
  • Peer Reviewed
• [Journal Article] Theoretical and experimental evidence for a new post-cotunnite phase of titanium dioxide with significant optical absorption (2011)
  • Author(s): Dekura, H., Tsuchiya, T., Kuwayama, Y., Tsuchiya, J
  • Journal Title: Physical Review Letters Volume: 107 Pages: 45701
  • Peer Reviewed
• [Presentation] Solubility of silicon in hcp-iron at high pressure (2013)
  • Author(s): Kuwayama, Y
  • Organizer: Japan Geoscience Union Meeting 2013
  • Place of Presentation: Chiba, Japan
  • Year and Date: 2013-05-21
• [Presentation] Solubility of silicon in hcp-iron at high pressure (2012)
  • Author(s): Kuwayama, Y
  • Organizer: AGU Fall Meeing 2012
  • Place of Presentation: San Francisco
  • Year and Date: 2012-12-03
• [Presentation] hcp 鉄への珪素の固溶量 (2012)
  • Author(s): 桑山靖弘
  • Organizer: 第53回高圧討論会
  • Place of Presentation: 大阪大学会館
  • Year and Date: 2012-11-07
• [Presentation] Mineralogical modeling of the anisotropic inner core based on the phase relations and elasticity of iron and iron alloys under the Earth's core condition (2011)
  • Author(s): Kuwayama, Y., Tsuchiya, T., Ohishi, Y
  • Organizer: AGU Fall Meeting 2011
  • Place of Presentation: San Francisco, CA, USA
  • Year and Date: 2011-12-09
• [Presentation] 地球核圧力における鉄合金の相平衡 (2011)
  • Author(s): 桑山靖弘,土屋卓久,大石泰生
  • Organizer: 第52回高圧討論会
  • Place of Presentation: 沖縄キリスト教学院
  • Year and Date: 2011-11-09
• [Book] Pyrite phases (pyrite-structure phases) as high pressure polymorphs of dioxides and other compounds Pyrite : Synthesis, Characterization and Uses (2013)
  • Author(s): Kuwayama, Y
  • Total Pages: 141-157