| Project/Area Number |
02555135
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | Osaka University |
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Principal Investigator |
MORI Hirotaro Research Center for UHVEM, Osaka University, Associate Professor, 超高圧電子顕微鏡センター, 助教授 (10024366)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUI Isao Naka Works, Hitachi Ltd., Senior Researcher, 那珂工場電子設計部, 研究員
FUJITA Hiroshi Research Inst. for Sci. Technology, Kinki University, Professor, 理工学総合研究所, 教授 (30028930)
YOSHIDA Kiyokazu Research Center for UHVEM, Osaka University, Technician, 教務員
YASUDA Hidehiro Department of Mat. Sci. Engng., Osaka University, Assistant Professor, 工学部, 助手 (60210259)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥8,200,000 (Direct Cost: ¥8,200,000)
Fiscal Year 1991: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1990: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | Atom Cluster / Ultrafine Particle / Ultra-high Voltage Electron Microscope / In Situ Observation / Fast Diffusion / Alloy Cluster / 超高電圧電子顕微鏡 / 合金化 / アトムクラスタ- |
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| Research Abstract |
When the size of a solid decreases to as small as several nm, its physical and chemical properties change remarkably as compared to those of a bulk solid. Hereafter such ultrafine particles are designated as atom clusters or simply clusters. However, studies on the diffusional properties in atom clusters are lacking. Based on this premise, in the present work, an atom-cluster generator for UHVEM was developed, and with the use of it, alloying behaviour in atom clusters was examined. The generator consisted of two spiral-shaped filaments made of tungsten. The generator was set in the specimen chamber of a 3MV HVEN. The distance between the filaments and a supporting film (substrate) for atom clusters was approximately 100 mm. An amorphous cabon film was used as the supporting film. With the use of the generator gold clusters of -3nm in size were first deposited on the supporting carbon film. Copper clusters were then formed on the same film. Change in the morphology and lattice constant of the clusters associated with the copper cluster deposition were studied in situ by transmission electron microscopy. It is revealed that upon the deposition of copper a rapid dissolution of copper into gold clusters has taken place. The observed copper diffusivity in gold clusters is approximately 9 orders of magnitude faster than that in bulk gold. It is also revealed that the center of gravity of the gold clusters has shown no visible translational motion during the alloying. These observations clearly indicate that deposited copper has either directly or after migration on the substrate, impinged upon and joined with gold clusters and has dissolved quickly into the interior of the gold clusters to form homogeneously mixed Au-Cu alloy clusters. This dissolution has taken place without visible translational motionof individual clusters on the supporting film.
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