1992 Fiscal Year Final Research Report Summary
Study of phase transition of ferroelectric polymers by use of molecular dynamics and x-ray diffraction
| Project/Area Number |
03455003
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
広領域
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| Research Institution | Hokkaido University of Education, Hakodate |
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Principal Investigator |
TAKAHASHI Nobuyuki Hokkaido University of Education, Hakodate, Associate Professor, 函館校, 助教授 (90163279)
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| Project Period (FY) |
1991 – 1992
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| Keywords | molecular dynamics simulation / structural phase transition / ferroelectric polymers / dipole orientation / electrostatic interaction / antiferroelectric phase / paraelectric phase / poly(vinylidene fluoride) |
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| Research Abstract |
Molecular dynamics simulations of the ferroelectric phase (low temperature phase) and a hypothetical paraelectric phase (high temperature phase) of poly(vinylidene fluoride) (PVDF) have clarified the following results.
(1) Control of macroscopic electric fields is necessary for the simulation of the ferroelectric phase of PVDF. The effects of the electric fields suggest that the electrostatic interaction stabilizes the ferroelectric phase of poly(vinylidene fluoride).
(2) The ferroelectric phase is transformed into nonpolar structures in the medium without polarization. The transition between the nonpolar phase and the ferroelectric phase is observed at low temperatures and suggests a possibility of antiferroelectric phase.
(3) The simulation of a nonpolar phase at high temperature shows a characteristic rotation and inversion motion of dipoles and the sliding diffusion of the molecular chain, It shows a possibility of the paraelectric phase.
(4) A nonlinear lattice size dependence of the anisotropic stress is observed at a high temperature phase of PVDF. This phenomenon gives an explanation of the structural phase transition accompanied by the stretching of the chain length induced by the pressure.
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