Theory for the evolution of ferroelectric, antiferroelectric, and ferrielectric smectic phases in the electric field.
Theory for the evolution of ferroelectric, antiferroelectric, and ferrielectric smectic phases in the electric field.
复制标题
电场中铁电、反铁电和亚铁电近晶相演化的理论。
DOI：
10.1103/physreve.82.031710
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
A. Emelyanenko
中科院分区：
文献类型：
--
作者：
A. Emelyanenko
在分子统计方法框架中研究了 Sm-C(A)*、双轴中间相和 Sm-C* 在电场中的演化 [A. V. Emelyanenko 等人，物理学。修订版 E 74, 011705 (2006)； A.V.Emelyanenko，欧洲。物理。 J.E 28, 441 (2009)]。绘制了包括各种倾斜近晶相存在可能性的“电场-温度”相图，并与实验相图进行了比较。还发现永久横向分子偶极矩（没有电场仅参与自发极化）在电场存在下产生诱导极化并产生非常强的介电效应。这种效应在 Sm-C* 中为正（倾斜面有沿着或逆着电场方向的倾向），在 Sm-C(A)* 和双轴中间相中为负（倾斜面有垂直于电场方向的倾向）。在亚铁电中间相中，自发极化和诱导极化都有相似的趋势，并在非常低的电场下提供螺旋展开。同时，Sm-C*中自发极化和激发极化提供的趋势相反，因此解旋阈值较大。结果表明，自发极化和诱导极化之间的相互作用可以导致复杂的双畴近晶结构的形成。发现了调节电场中 Sm-C*、Sm-C(A)* 和双轴中间相结构演化的单一参数。我们假设双畴螺旋结构与某些材料中存在于 Sm-C* 下面的附加铁电相 FiLC 相同。数值计算是在作者开发的 AFLC 相图绘图软件的帮助下完成的，该软件可在他的网页上找到。
An evolution of Sm-C(A)∗, biaxial intermediate phases, and Sm-C∗ in the electric field is investigated in a framework of molecular-statistical approach [A. V. Emelyanenko et al., Phys. Rev. E 74, 011705 (2006); A. V. Emelyanenko, Eur. Phys. J. E 28, 441 (2009)]. The "electric field-temperature" phase diagrams including the possibility of existence of various tilted smectic phases are plotted and compared with the experimental ones. Permanent transverse molecular dipole moments (without electric field participating only in the spontaneous polarization) were also found to generate the induced polarization in the presence of electric field and to produce very strong dielectriclike effect. This effect is positive in Sm-C∗ (tilt planes have a tendency of orienting along or against the electric field) and is negative in Sm-C(A)∗ and in biaxial intermediate phases (tilt planes have a tendency of orienting perpendicular to the electric field). In the ferrielectric intermediate phases both spontaneous and induced polarizations favor similar tendencies and provide the helix unwinding at very low electric field. At the same time, the tendencies provided by spontaneous and induced polarizations are opposite in Sm-C∗, and therefore the unwinding threshold is larger. It was shown that interplay between spontaneous and induced polarizations can lead to the formation of complex bidomain smectic structures. A single parameter regulating an evolution of structure of Sm-C∗, Sm-C(A)∗, and biaxial intermediate phases in the electric field was found. We suppose that bidomain helical structure is the same as additional ferrielectric phase FiLC existing in some materials just below Sm-C∗. The numerical calculations are done with help of AFLC phase diagram plotter software developed by the author and available at his webpage.