| Project/Area Number |
12640325
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Aichi Shukutoku University |
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Principal Investigator |
ISHIBASHI Y Aichi Shukutoku Univ., Prof., コミュニケーション学部, 教授 (00023052)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2001: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Ferroelectrics / Solid solutions / Phase diagram / Perovskite-type oxides / Morphotropic phase boundary / Phase transition / Polarization reversal / Engineered domains / ペロヴスカイト酸化物 / 誘電率 / 弾性率 |
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| Research Abstract |
The purpose of this project for constructing the theory on the solid solution system of perovskite-type oxide ferroelectrics has been almost fully achieved. It has been clarified that physical origins of the appearance of morphotropic phase boundary(MPB) in the solid solution system is that the Landau-type free enrgy function becomes isotropic in the transition parameter space, depending upon the concentration of the end members. This aspect of isotropic free energy at MPB gives rise to excellent physical properties like large dielectric and elastic compliances and large electromechanical coupling constants. These findings can be utilized as a guiding principle in search of materials with large compliances, and in fact N. Yasuda (Gifu Univ.), following the suggested principle, succeeded in finding a material with a very large electromechanical coupling constant in the PZN-PT solid solution system.
Isotropy, or small anisotropy in a more strict sense, of the free energy affects polarization reversal kinetics. Namely, it has been found that pseudo-rotation of polarization takes place in the reversal process because of isotropy of the free energy, and as a result the speed of polarization reversal increases as the composition approaches MPB.
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