Flexoelectricity in an oxadiazole bent-core nematic liquid crystal
Flexoelectricity in an oxadiazole bent-core nematic liquid crystal
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DOI：
10.1063/1.4903242
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发表时间：
2014-12
影响因子：
4
通讯作者：
S. Kaur;V. Panov;C. Greco;A. Ferrarini;V. Görtz;J. Goodby;H. Gleeson
中科院分区：
文献类型：
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作者：
S. Kaur;V. Panov;C. Greco;A. Ferrarini;V. Görtz;J. Goodby;H. Gleeson
我们通过测量恶二唑弯曲核液晶形成挠曲微区的临界电压及其波数，实验测定了其伸展和弯曲挠曲电系数|e1−e3|的大小。该系数|e 1−e3|是大多数常规向列相液晶的2-3倍，在−60 K向列区变化范围为8pcm−1到20pcm∼1。将密度泛函理论计算与分子场方法和原子模拟相结合，计算了弯芯液晶的偶极和四极贡献的挠曲电系数e1和e3。有趣的是，弯曲弯曲电系数的大小被发现相当小，这与人们对弯曲核分子的普遍预期相反。计算结果与实验值很好地吻合，提供了分子参数对弯曲电系数的影响的洞察力，并展示了在预测弯曲核液晶中弯曲电行为的巨大潜力。
We have determined experimentally the magnitude of the difference in the splay and bend flexoelectric coefficients, |e 1 − e 3|, of an oxadiazole bent-core liquid crystal by measuring the critical voltage for the formation of flexodomains together with their wave number. The coefficient |e 1 − e 3| is found to be a factor of 2–3 times higher than in most conventional calamitic nematic liquid crystals, varying from 8 pCm−1 to 20 pCm−1 across the ∼60 K—wide nematic regime. We have also calculated the individual flexoelectric coefficients e 1 and e 3, with the dipolar and quadrupolar contributions of the bent-core liquid crystal by combining density functional theory calculations with a molecular field approach and atomistic modelling. Interestingly, the magnitude of the bend flexoelectric coefficient is found to be rather small, in contrast to common expectations for bent-core molecules. The calculations are in excellent agreement with the experimental values, offering an insight into how molecular parameters contribute to the flexoelectric coefficients and illustrating a huge potential for the prediction of flexoelectric behaviour in bent-core liquid crystals.