| Project/Area Number |
11650035
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
表面界面物性
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| Research Institution | OKYAMA UNIVERSITY OF SCIENCE |
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Principal Investigator |
YOKOTA Yasuhiro OKAYAMA UNIV.OF SCI., NATURAL RESEARCH INSTI., PROFESSOR, 自然科学研究所, 教授 (50200902)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2000: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1999: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | electron diffraction / imaging plate / chalogenide / phase transition / super structure / manganese oxides / tunnel structure / hydrothermal / resistivity / 酸化マンガン化合物 / トンネル構造 / リチウムマンガン酸化物 |
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| Research Abstract |
The imaging plates (IP) were used for recording electron diffraction patterns of layered transition metal chalcogenides and manganeis oxides with tunnel structure. A ternary chalcogenide, α-BaCu_4S_3, shows a structural phase transition at 188-205K.The electron diffraction patterns were recorded both room temperature phase and low temperature phase. The crystallographic description of room temperature phase was orthorombic with the space group of Pnma. Upon cooling, the copper atoms in the channels start to modified. Electron diffraction studies revealed that the phase transition was accompanied by the formation of the superstructure with a wave vector of q = 1/5b^*. The observed superlattice electron diffraction patterns were analyzed on the basis of superstrucure model using multi-slice calculation method. The diffraction patterns were well explained by the simulation patterns.
Tunnel and layered manganese oxides constitute a large family of porous materials. Alk-Mn_<24>O_<48> (alk-RUB-7, alk=Rb, K) with 2 x 4 tunnel structure has been investigated using electron diffraction recorded with IP systems. Specimen manganese oxides were hydrothermally prepared. Temperature dependence of the resistivity of this material showed a small anomaly at 220K, indicating the presence of a phase transition. magnetic susceptibility obeyed a Curie-Weiss law above 77K.Also satellite spots were observed at ED patterns of the liquid nitrogen specimen temperature.
Further studies will be necessary to clarify fully the complex phase transition behavior of the present system.
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