| Project/Area Number |
11650015
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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 |
Applied materials science/Crystal engineering
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| Research Institution | Osaka University |
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Principal Investigator |
UYEDA Chiaki Graduate School of Science, Osaka University Associate Professor, 大学院・理学研究科, 助教授 (50176591)
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| Co-Investigator(Kenkyū-buntansha) |
OHOTAKA Osamu Graduate School of Science, Osaka University Associate prof., 大学院・理学研究科, 助教授 (40213748)
TAKEI Humihiko Graduate School of Science, Osaka University Professor, 大学院・理学研究科, 名誉教授 (60005981)
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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: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | Fine particle / Si / Disproportionation reaction / SiO / Activation energy / 不均化反応 / 反磁性異方性 / ケイ酸塩 / 電子分布 / シリコンナノクリスタル / 熱分解 / 超微粒子 / シリコン / SiO / 反応速度 / 一酸化硅素 |
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| Research Abstract |
The present work has achieved a new simple method for preparation of fine Si particles in a solid state. This method is based on a solid state oxidation-reduction reaction of amorphous silicon monoxide (SiO) to Si and SiO_2. The reaction, traditionally called "disproportionation reaction", proceeds with the following chemical formula ; 2SiO→Si+SiO_2, where both the oxidation of Si[II] to Si[IV] and the reduction to Si[0] simultaneously occur on heating. As a result, crystalline Si was precipitated above 900℃ in amorphous SiO_2 media. Electron microscope analyses revealed that Si appeared in a form of fine single-crystal particles whose mean size was controlled only by the reaction temperature from several to several ten nm. Fine Si particles have been prepared by the disproportionation reaction of silicon monoxide (SiO), that is : 2SiO→Si+SiO_2. Amorphous powders of SiO are heated between 900 and 1400℃ in a flow of Ar and the obtained specimens are analyzed by X-ray powder diffraction and high resolution transmission electron microscopy. The treatments between 1000 and 1300℃ for more than 0.5 hour result in origination of Si particles dispersed in amorphous oxide media. The particle size varies from 1-3 to 20-40 nm, depending on the heating temperature. Kinetic analyses of the reaction reveal that the activation energy is 1.1 eV (82.1 kJ mol^<-1>). The specimens annealed above 1350℃ changes into a mixture of Si and cristobalite, suggesting a transformation in the surrounding oxides from the amorphous to crystalline states.
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