Nano-electromechanical rotation of graphene and giant enhancement in dielectric anisotropy in a liquid crystal
Nano-electromechanical rotation of graphene and giant enhancement in dielectric anisotropy in a liquid crystal
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DOI：
10.1063/1.4921752
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发表时间：
2015-05-18
影响因子：
4
通讯作者：
Garvey, Alfred
中科院分区：
文献类型：
--
作者：
Basu, Rajratan;Kinnamon, Daniel;Garvey, Alfred
向列型液晶（LC）掺杂有稀浓度的原始单层石墨烯（GP）薄片，并且发现LC + GP混合物的介电各向异性显着增加。电场依赖的电导研究表明，石墨烯片遵循随施加电场增加而机械旋转的方向性。进一步的研究表明，石墨烯的蜂窝结构和LC的苯环之间的p-p电子堆叠稳定了伪介电畴，伪介电畴通过改善介电相中的取向有序参数而共同放大了介电各向异性。这些各向异性域与外部电场相互作用，导致各向同性相中的非零介电各向异性。由于LC-石墨烯耦合，介电各向异性的增强被发现对LC的取向阈值场和弹性具有随后的积极影响，其允许电致伸缩导向器在关闭电场时更快地响应。(C)2015 AIP Publishing LLC.
A nematic liquid crystal (LC) is doped with dilute concentrations of pristine monolayer graphene (GP) flakes, and the LC + GP hybrids are found to exhibit a dramatic increase in the dielectric anisotropy. Electric field-dependent conductance studies reveal that the graphene flakes follow the nematic director that mechanically rotates on increasing an applied electric field. Further studies show that the p-p electron stacking, between the graphene's honeycomb structure and the LC's benzene rings, stabilizes pseudo-nematic domains that collectively amplify the dielectric anisotropy by improving the orientational order parameter in the nematic phase. These anisotropic domains interact with the external electric field, resulting in a nonzero dielectric anisotropy in the isotropic phase as well. The enhancement in dielectric anisotropy, due to the LC-graphene coupling, is found to have subsequent positive impacts on the LC's orientational threshold field and elasticity that allows the nematic director to respond quicker on switching the electric field off. (C) 2015 AIP Publishing LLC.