Theoretical studies of the influence of nanoparticle dopants on the ferroelectric properties of a ferroelectric liquid crystal
Theoretical studies of the influence of nanoparticle dopants on the ferroelectric properties of a ferroelectric liquid crystal
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DOI：
10.1016/j.molliq.2018.01.013
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发表时间：
2018-03
影响因子：
6
通讯作者：
S. Shoarinejad;R. M. Siahboomi;M. Ghazavi
中科院分区：
文献类型：
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作者：
S. Shoarinejad;R. M. Siahboomi;M. Ghazavi
近年来，掺杂纳米颗粒的铁电液晶（FLCs）因其令人着迷的基础和技术前景而受到广泛关注。本文的目的是在理论上尝试研究铁电纳米粒子对铁电液晶性能的影响。我们的研究是基于铁电近晶C （SmC*）相向相应的近晶A （SmA）相过渡的扩展热力学模型。我们使用了改进的朗道自由能，这是为球形纳米颗粒浸泡在FLC介质中的统计力学而开发的。研究了外加电场作用下FLC分散铁电纳米粒子的响应时间。在温度和纳米颗粒浓度可能变化的情况下，还计算了旋转粘度。所得结果表明，在金石模式下，纳米掺杂体系的响应时间比纯掺杂体系快。此外，观察到纯体系和掺杂体系的旋转粘度之间存在显著差异。计算了偏振角和倾斜角的变化。结果表明，在过渡温度附近，分散的铁电纳米粒子对FLC的极化有影响，并证实了粒子的存在对FLC的倾斜角没有显著影响。此外，铁电纳米掺杂体系的自发极化略低。基于该模型的计算结果与最近的实验结果吻合较好。
Recently, ferroelectric liquid crystals (FLCs) doped with nanoparticles have received extensive interest owing to their fascinating fundamental and technological perspectives. The purpose of this paper is to present our theoretical attempt to study the effects caused by ferroelectric nanoparticles on the properties of a ferroelectric liquid crystal. Our study is based on an extended thermodynamic model of the ferroelectric smectic C (SmC*) phase near the transition to the corresponding smectic A (SmA) phase. We have used the modified Landau free energy, developed for statistical mechanics of the spherical nanoparticles immersed in a FLC medium. The response time of the FLC dispersed ferroelectric nanoparticles is investigated under an applied electric field. The rotational viscosity is also calculated with the possible variation in temperature and the nanoparticle concentration. The obtained results, for the goldstone mode, show a faster response time for the nanodoped system as compared to the pure one. Moreover, a remarkable difference between the rotational viscosities of the pure and doped systems is observed. The variations of polarization and tilt angle are calculated as well. The obtained results for both pure and nanodoped FLC system, near the transition temperature, show the influence of dispersed ferroelectric nanoparticles on the FLC polarization and confirm that the tilt angle is not significantly affected by the presence of the particles. Also, slightly lower spontaneous polarization is revealed for a ferroelectric nanodoped system. Calculations based on this model show a good agreement with the recent experimental findings.