Understanding the unusual reorganization of the nanostructure of a dark conglomerate phase.
Understanding the unusual reorganization of the nanostructure of a dark conglomerate phase.
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了解暗砾岩相纳米结构的异常重组。
DOI：
10.1103/physreve.91.042504
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Nagaraj M
中科院分区：
文献类型：
--
作者：
Nagaraj M
弯芯液晶显示出的暗团聚体(DC)相具有显著的性质，包括电场可调的手性磁区结构和折射率大幅下降(0.045)，同时在交叉偏振器下观察到仍保持光学暗织构。对该系统进行了详细的研究，得到了一个与实验观测完全一致的模型。它报道了在直流阶段观察到的两个不同的区域：一个较高的温度区域，其中由小角x射线散射测量的周期略有减小(0.5%)和一个较低的温度区域，它显著地增加(16%)。此外，本文还讨论了在这两种情况下观察到的不寻常的电场诱导相变。这些变化具有与温度和频率相关的阈值电场，尽管观察到的现象与器件厚度、几何形状和对准层无关。直流阶段的电光行为对应于一些结构变化，导致物理性质的异常变化，包括周期性的小幅增加(1%)和平均介电常数的翻倍。我们提出了一种DC相的模型，在基态下，相的纳米结构表现出反倾斜的反铁电组织。在电场作用下，在保持DC相整体海绵状结构不变的情况下，它经历了分子重排，而没有任何明显的结构变化，导致了反倾斜的铁电有序。
The dark conglomerate (DC) phase exhibited by a bent-core liquid crystal shows remarkable properties including an electric-field tunable chiral domain structure and a large (0.045) reduction of refractive index, while maintaining an optically dark texture when observed under crossed polarizers. A detailed investigation of the system is presented, leading to a model that is fully consistent with the experimental observations. It reports the observation of two distinct regimes in the DC phase: a higher temperature regime in which the periodicity measured by small angle x-ray scattering decreases slightly (0.5%) and a lower temperature regime where it increases considerably (16%). Also, the paper discusses the unusual electric-field-induced transformations observed in both the regimes. These changes have threshold fields that are both temperature and frequency dependent, though the phenomena are observed irrespective of device thickness, geometry, and the alignment layer. The electro-optic behavior in the DC phase corresponds to a number of structural changes leading to unusual changes in physical properties including a small (1%) increase in periodicity and a doubling of the average dielectric permittivity. We propose a model of the DC phase where in the ground state the nanostructure of the phase exhibits an anticlinic antiferroelectric organization. Under an electric field, it undergoes a molecular rearrangement without any gross structural changes leading to an anticlinic ferroelectric order while keeping the overall sponge-like structure of the DC phase intact.
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DOI：
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