Japan Geoscience Union Meeting 2018

Presentation information

[EE] Evening Poster

S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Tectonophysics

[S-IT22] Interaction and Coevolution of the Core and Mantle in the Earth and Planets

Tue. May 22, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Tsuyoshi Iizuka(University of Tokyo), Hidetoshi Shibuya(Department of Earth and Environmental Sciences, Faculty of Advanced Science and Technology, Kumamoto University), Taku Tsuchiya(愛媛大学地球深部ダイナミクス研究センター, 共同), Kenji Ohta(Department of Earth and Planetary Sciences, Tokyo Institute of Technology)

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

*Hokai Fujitani1, Taku Tsuchiya1 (1.Ehime University Geodynamics Research Center)

Keywords:Fe3+, ferropericlase, First-principles calculation

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.