Presentation Information
[R2P-01]Hydrogen incorporation mechanism in the lower-mantle bridgmanite
Narangoo Purevjav1, Naotaka Tomioka2, Shigeru Yamashita7, Keiji Shinoda3, Sachio Kobayashi2, Kenji Shimizu2, Motoo Ito2, Suyu Fu4, Jesse Gu4, Christina Hoffmann5, Jung-Fu Lin4, *Takuo Okuchi6 (1. Univ. Bayreuth, 2. JAMSTEC, 3. Osaka Metropolitan Univ., 4. Univ. Texas, 5. ORNL, 6. Kyoto Univ., 7. Okayama Univ.)
Keywords:
bridgmanite,lower mantle,hydrogen substitution,neutron diffraction
We investigated the crystallographic site of hydrogen and its incorporation mechanism in bridgmanite by single-crystal neutron diffraction for the first time. Our results show that the primary hydrogen site has an OH bond direction nearly parallel to the crystallographic b_axis of the bridgmanite lattice, where hydrogen is located between two oxygen anions to form a straight geometry of covalent and hydrogen bonds. Our modelled results show that hydrogen is incorporated via substitution of Al3+ + H+ simultaneously exchanging for Si4+, which does not require any cation vacancy.
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