TY - JOUR
T1 - Determination of hydrogen site and occupancy in hydrous Mg2SiO4 spinel by single-crystal neutron diffraction:
AU - Purevjav, Narangoo
AU - Okuchi, Takuo
AU - Wang, Xiaoping
AU - Hoffmann, Christina
AU - Tomioka, Naotaka
N1 - Funding Information:
The following funding is acknowledged: Japan Society for the Promotion of Science (JSPS DC2 to Narangoo Purevjav; JSPS KAKENHI No. 15J03633 to Narangoo Purevjav; JSPS Postdoctoral Fellowship for Research in Japan No. P17331 to Narangoo Purevjav; JSPS KAKENHI No. 26287135 to Takuo Okuchi; JSPS KAKENHI No. 17H01172 to Takuo Okuchi). Part of the research conducted at Oak Ridge National Laboratory’s Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.
Publisher Copyright:
© Narangoo Purevjav et al. 2018.
PY - 2018/2/1
Y1 - 2018/2/1
N2 - Ringwoodite [(Mg,Fe2+)2SiO4 spinel] has been considered as one of the most important host minerals of water in the Earth's deep mantle. Its extensive hydration was observed in high-pressure synthesis experiments and also by its natural occurrence. Water can dissolve into ringwoodite as structurally bound hydrogen cations by substituting other cations, although the hydrogen site and its occupancy remain unclear. In this study, neutron time-of-flight single-crystal Laue diffraction analysis was carried out for synthetic hydrous ringwoodite. Hydrogen cations were found only in the sites in MgO6 octahedra in the ringwoodite structure, which compensated the reduced occupancies of both magnesium and silicon cations. The refined cation occupancies suggest that the most plausible hydration mechanism is that three hydrogen cations simultaneously occupy an MgO6 octahedron, whereas four such hydrogenated octahedra surround a vacant SiO4 tetrahedron.A single-crystal neutron diffraction study was performed on hydrogen incorporation in ringwoodite, which is the most important host mineral of water in the Earth's deep mantle. Its hydrogen incorporation mechanism, bonding geometry and occupancy at the relevant hydrogen site were unambiguously revealed.
AB - Ringwoodite [(Mg,Fe2+)2SiO4 spinel] has been considered as one of the most important host minerals of water in the Earth's deep mantle. Its extensive hydration was observed in high-pressure synthesis experiments and also by its natural occurrence. Water can dissolve into ringwoodite as structurally bound hydrogen cations by substituting other cations, although the hydrogen site and its occupancy remain unclear. In this study, neutron time-of-flight single-crystal Laue diffraction analysis was carried out for synthetic hydrous ringwoodite. Hydrogen cations were found only in the sites in MgO6 octahedra in the ringwoodite structure, which compensated the reduced occupancies of both magnesium and silicon cations. The refined cation occupancies suggest that the most plausible hydration mechanism is that three hydrogen cations simultaneously occupy an MgO6 octahedron, whereas four such hydrogenated octahedra surround a vacant SiO4 tetrahedron.A single-crystal neutron diffraction study was performed on hydrogen incorporation in ringwoodite, which is the most important host mineral of water in the Earth's deep mantle. Its hydrogen incorporation mechanism, bonding geometry and occupancy at the relevant hydrogen site were unambiguously revealed.
KW - Earth's deep mantle
KW - crystallography of hydrogen
KW - neutron diffraction
KW - ringwoodite
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U2 - 10.1107/S2052520618000616
DO - 10.1107/S2052520618000616
M3 - Article
AN - SCOPUS:85041669023
VL - 74
SP - 115
EP - 120
JO - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
JF - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
SN - 2052-5192
IS - 1
ER -