日本地球惑星科学連合2023年大会

講演情報

[E] オンラインポスター発表

セッション記号 S (固体地球科学) » S-IT 地球内部科学・地球惑星テクトニクス

[S-IT16] 地球深部科学

2023年5月26日(金) 09:00 〜 10:30 オンラインポスターZoom会場 (2) (オンラインポスター)

コンビーナ:土屋 旬(愛媛大学地球深部ダイナミクス研究センター)、太田 健二(東京工業大学理学院地球惑星科学系)、河合 研志(東京大学大学院理学系研究科地球惑星科学専攻)、飯塚 毅(東京大学)

現地ポスター発表開催日時 (2023/5/25 17:15-18:45)

09:00 〜 10:30

[SIT16-P13] Effect of hydrogen on rheology of hcp-Fe

*西原 遊1呉 文天1國本 健広1高市 合流1久保田 哲矢1辻野 典秀2柿澤 翔2肥後 祐司2 (1.愛媛大学地球深部ダイナミクス研究センター、2.高輝度光科学研究センター)

キーワード:内核、鉄水素化物、レオロジー

Among candidates for the light element(s) in the Earth’s core, hydrogen is one of the most important candidates. Although many hypotheses have been proposed for the origin of the inner core seismic anisotropy, there is no general consensus for its origin partly due to lack of accurate information of viscosity in the inner core. In this study, we have studied effect of hydrogen on the rheology of iron based on high-pressure and high-temperature deformation experiments.
A high-pressure deformation apparatus D111-type apparatus was recently installed on a synchrotron beamline BL04B1, SPring-8. We have conducted in-situ high-pressure deformation experiments on iron hydride (FeHx) using this apparatus. Steady-state deformation of double hexagonal close-packed (dhcp)-FeHx with x = 0.74-0.84 was observed at 39 conditions in pressure of 11.7-16.1 GPa and temperature of 573-823 K. Stress values of dhcp-FeHx were only slightly lower than those of hcp-Fe at same conditions. Stress exponent and activation enthalpy at 14 GPa of dhcp-FeHx were determined to be 3.2 and 220 kJ/mol, respectively, at temperatures higher than ~750 K suggesting that power-law dislocation creep is dominant. Several experiments were conducted on hexagonal close-packed (hcp)-FeHx with x = 0.2-0.3. Stress values of hcp-FeHx were also only slightly lower than those of hcp-Fe at same conditions. These results suggests that influence of hydrogen on the inner core viscosity is limited.