1989 Fiscal Year Final Research Report Summary
Neutron diffraction study of structure of molten alkali hydroxides
| Project/Area Number |
63470008
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
構造化学
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
OKADA Isao Tokyo Inst. Tech., Dept. Electronic Chem., Professor, 総合理工学研究科, 教授 (60011582)
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| Co-Investigator(Kenkyū-buntansha) |
HABASAKI Junko Tokyo Inst. Tech., Dept. Electronic Chem., Assistant Instructor, 総合理工学研究科, 教務技官 (10133331)
OKAZAKI Susumu Tokyo Inst. Tech., Dept. Electronic Chem., Research Associate, 総合理工学研究科, 助手 (70194339)
ODAWARA Osamu Tokyo Inst. Tech., Dept. Electronic Chem., Associate Professor, 総合理工学研究科学, 助教授 (90185611)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Molten Salt / Hydroxide / Structure / Neutron Diffraction / Raman Scattering / Molecular Dynamics Simulation / Rotational Relaxation / Vibrational Relaxation |
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| Research Abstract |
1. Neutron scattering measurements have been performed for molten LiOD, NAOD, and KOD using a nickel metal cell. Large scattering intensities by the cell could be successfully subtracted from the observed total intensities. The structure factors and their Fourier transformations reveal that the polyatomic ion can possess an effective ionic radius.
2. Fine structure of molten LiOH has been elucidated from molecular dynamics simulation combined with the neutron scattering measurement.
(1) Li^+ ion coordinates OH^- ion mainly on the 0 atom side. The most probable location is that r_<LiO> = 1.95 A^^ﾟ and rheta_<Li-O-H> = 115ﾟ, which is somewhat different from that of LiOH molecule in vacuum.
(2) The Li^+ ion coordinates in a certain probability also on the H atom side. This is one of the characteristics of liquids which cannot be found in the solid.
(3) With regard to the framework structure of the melt, OH^- ion takes tetrahedral coordination around Li^+ ion. On the other hand, four Li^+ ions coordinate just to the O atom of the OH^- ion to form a slightly folded square plane.
3. Polarized and depolarized Raman scattering measurements have also been accomplished for LiOH, NaOH, KOH, RbOH, and CsOH. Band contour analysis revealed that vibrational relaxation rate depends largely on the counter cations, while rotational relaxation rate does not so much. Also in the rotational autocor relation function, oscillatory rapid decay at small t and exponential slow one at large t are found. The former is caused by the liberation of the OH^- ion and the latter seems to be accompanied by structural rearrangement of the surrounding Li^+ ions.
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Research Products
(18 results)
