日本地球惑星科学連合2018年大会

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[EE] 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-IT22] 核-マントルの相互作用と共進化

2018年5月22日(火) 10:45 〜 12:15 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:飯塚 毅(東京大学)、渋谷 秀敏(熊本大学大学院先端科学研究部基礎科学部門地球環境科学分野)、土屋 卓久(愛媛大学地球深部ダイナミクス研究センター、共同)、太田 健二(東京工業大学大学院理工学研究科地球惑星科学専攻)

[SIT22-P18] First-principles study on the site occupancy of Fe3+ in ferropericlase (Mg,Fe)O

*藤谷 宝海1土屋 卓久1 (1.愛媛大学地球深部ダイナミクス研究センター)

キーワード:Fe3+、フェロペリクレース、第一原理計算

A high vacancy concentration due to the extrinsic mechanism is considered to be reproduced rheological property of Earth’s lower mantle via diffusion creep (e.g., Ita and Cohen 1998). Charge unneutral Fe3+ is one of the major impurities to create vacancies as the following reaction 3Mg× 2Fe. + V''. It has been experimentally reported that the site occupancy of Fe3+ changes from the octahedral site to the tetrahedral in MgO with increasing pressure around 15 GPa (Otsuka et al., 2010), leading to a further increase of the vacancy concentration in the octahedral site. However, little is known about the effects of Fe3+/vacancy configuration and the spin transition on its site preference, the differences in chemical bonds around octahedral and tetrahedral Fe3+. In this study, we investigate Fe3+ bearing MgO by using first-principles calculation methods based on the density functional theory up to 150 GPa. The tetrahedral occupation of Fe3+ is so fur not found in all the defect configurations and pressure condition examined, being not consistent with experimental findings.