2016 Fiscal Year Annual Research Report
乱れを制御可能な系におけるガラス転移・ジャミングの研究
| Project/Area Number |
15F15325
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| Research Institution | The University of Tokyo |
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Principal Investigator |
田中 肇 東京大学, 生産技術研究所, 教授 (60159019)
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| Co-Investigator(Kenkyū-buntansha) |
TONG HUA 東京大学, 生産技術研究所, 外国人特別研究員
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| Project Period (FY) |
2015-11-09 – 2018-03-31
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| Keywords | Grass Transition / Correlatiom / Order Parameter |
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| Outline of Annual Research Achievements |
1. We have studied "Hidden structural origin of both fast and slow glassy dynamics in supercooled liquids". We introduce a set of new structural order parameters characterizing sterically favored structures with high local packing capability, and then access structure-dynamics correlation by a novel nonlocal approach. We find that the fast β process is controlled by the instantaneous order parameter field locally, resulting in short-time particle-scale dynamics, whereas the slow α process is controlled by the structure over a static length which grows coherently with the dynamic one upon cooling. Thus, a static structure has two intrinsic characteristic lengths, particle size and ξ, which control dynamics in local and nonlocal manners, resulting in the emergence of the two key relaxation modes, fast β and slow α processes, respectively. The presence of such intrinsic structure-dynamics correlation strongly indicates a thermodynamic nature of glass transition.
2. We have studied “Correlation between structure, dynamics, and mechanical response in glassy systems” and found the following:(1) The force and stress fields decouple with the geometric structure in the inherent structures; (2) The vibrational motion in glasses at low temperature decouples with the geometric structure;(3) The α-relaxation procession is correlated with the geometric structure;(4) The relation between the long-range stress correlation and glassy dynamics is clarified.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
1. For project "Hidden structural origin of both fast and slow glassy dynamics in supercooled liquids", the analyses have been finished and we are planning to submit the paper very soon.
2. For project "Correlation between structure, dynamics, and mechanical response in glassy systems”, beside the achievements already obtained, we are now performing extensive studies in other model glass systems to check the generality of our results and trying to quantify the relation between the structural, dynamical, and mechanical correlations.
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| Strategy for Future Research Activity |
Besides the studies specified in the above "Current progress" section, we plan to do the following:
1. "Inherent structural characteristics of amorphous solids". Here we will characterize the structure of amorphous solids from the mechanical aspect. We expect that this may provide an universal description of amorphous solids of various kinds and therefore help to understand their peculiar low-temperature properties.
2. "Role of inherent states for dynamics in glassy materials". Here we will clarify the role of inherent state at different temperatures, from supercooled liquids to solid states. We expect that the inherent states are not relevant at high temperatures and become important in low-temperature limit. The mechanism behind such change of the role of inherent states would be the research focus.
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