| Project/Area Number |
18K13981
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 26010:Metallic material properties-related
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| Research Institution | The University of Tokyo |
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Principal Investigator |
Tochigi Eita 東京大学, 大学院工学系研究科(工学部), 助教 (50709483)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2018: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 変形双晶 / 双晶転位 / アルミナ / 透過型電子顕微鏡 / その場観察 / 分子動力学計算 / TEM/STEM / 粒界 |
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| Outline of Final Research Achievements |
The atomic structure of the rhombohedral twin in sapphire was observed scanning transmission electron microscopy. The interfaces were found to take the terrace-step structure. Based on the experimental observations, the interface structure model with the step was contracted, and the migration of the step was simulated by first-principles molecular dynamic calculations. It was revealed that the step migrates along the interface. The step migration is mediated by the cooperative motion of two Al and three O atoms located within the step height. It was concluded that the elementary process of the rhombohedral twinning in sapphire is associated with the cooperative motion of the five atoms.
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| Academic Significance and Societal Importance of the Research Achievements |
変形双晶は結晶性材料に共通した塑性変形モードであり、古くから研究が進められてきた。結晶学的な対称性による要請から、変形双晶の形成にはシャッフリングと呼ばれる原子集団の協調的な運動が生じるものと考えられているが、その詳細な機構は良くわかっていない。本研究においては、サファイヤ中の菱面双晶は、わずか5原子からなる集団の連鎖的なシャッフリングにより、形成・成長することが明らかとなった。本結果は、変形双晶の形成・成長に関する原子論的メカニズムの一端を解明したものであり、学術的に重要な成果であると考えられる。
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