Study of Mechanisms of Crystal Growth of Ferroelectric Polymers by Means of Measurement of Nonlinear Dielectric Spectrum

铁电聚合物与铁电陶瓷的质的区别越来越明显。具体来说，我们在极化的形成和逆转、晶体生长、准电-铁电相变等现象中观察到显著的聚合物效应。本研究结果总结如下：1)我们成功地开发了一个新的系统，可以精确和容易地测量非线性性质，如电伸缩，二阶和三阶介电常数。2)二阶介电常数反映了晶体的极化状态，三阶介电常数反映了Curite转变的热力学顺序，通过电伸缩常数的计算阐明了VDF/TrFE共聚物中压电性的起源。提出了一种铁电聚合物理论。我们发现聚合物晶体的电特性受到分子间相互作用、分子内相互作用和相互竞争的影响。除了VDF等铁电聚合物外，还研究了奇数尼龙的铁电性能。我们发现它的铁电性受到氢键的强烈影响。

Qualitative difference of ferroelectric polymers from ferroelectric ceramics is becoming clearer. Specifically, we observed remarkable polymer effects in phenomena such as formation and reversal of polarization, crystal growth, paraelectric-ferroelectric phase transition. Results of this study are summarized as follows.1) We succeeded in development of a new system to measure exactly and easily nonlinear properties such as electrostriction, second order and third order dielectric constants.2) We foud tha t a second order dielectric constant reflects a polarization state of crystals and a third order dielectric constant reflects the thermodynamical order of the Curite transision, The origin of piezoelectricity in VDF/TrFE copolymers was elucidated by an evaluation of an electrostriction constant.A theory of ferroelectric polymers was proposed. We found that the forroelectric properties of polymer crystals are affected by intermolecular interaction and intramolecular one and those competition.In addition to ferroelectric polymers including VDF, the ferroelectric properties of odd-number nylon were investigated. We found that its ferroelectricity is strongly affected by the hydrogen bonds.