2006 Fiscal Year Final Research Report Summary
Structure and dynamics of water and silicon in carbon nanotube
| Project/Area Number |
15201021
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nanostructural science
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
TANAKA Hideki OKAYAMA UNIVERSITY, Graduate School of Natural Science and Technology, Professor, 大学院自然科学研究科, 教授 (80197459)
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| Project Period (FY) |
2003 – 2006
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| Keywords | Water / Nanotubes / Simulation / Phase Transition |
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| Research Abstract |
Recent computational studies showed that spherical particles take several chiral and achiral one-dimensional structures when closely packed in narrow cylindrical pores and an experimental study confirmed that C60 molecules form some of the predicted structures in carbon nanotubes. These results for different systems imply generic phase behaviour of spherical particles in cylindrical cavities but our knowledge on possible phases is yet fragmentary and nature of phase transformations among them is little explored. Here we show for a model system of argon in carbon nanotubes that first ten solid phases are in one-to-one correspondence with the first ten ways of folding a triangular lattice, each being characterized by a roll-up vector like the single-walled carbon nanotube. We then obtain, by inherent-structure calculation and molecular dynamics simulation, phase diagrams of the system in pressure-diameter and temperature-diameter planes, thereby being able to unveil the layered surfaces of phase boundaries that eventually disappear as temperature is increased. Consequences of such phase boundaries are that two types of freezing, gradual and abrupt transformation, are possible for any of the one-dimensional solids, that changing the tube diameter by a tenth of particle's diameter may alter the resulting solid phase as well as the type of freezing behaviour, and that changing the pressure may induce several structural changes in a given nanotube but changing the temperature may only give rise to a single, and in most cases gradual, liquid-solid phase transformation.
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