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1.
S. Eren San Mustafa Okutan Oguz Koysal Yusuf Yerli 《中国物理快报》2008,25(1):212-215
Fullerene C60, C7o, single-walled and multi-walled carbon nanotubes and graphene sheets are doped to nematic liquid crystal (LC) host in the same percentage. Planar samples of these mixtures are prepared and our measurements constitute an optimization basis for possible applications. Fullerene balls are found to be the best compatible material for optical aims and reorientation of LC molecules, while the carbon nanotubes experience some reorientation possibility in LC media and graphene layers are good barriers to preserve reorientation. 相似文献
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研究了掺杂两种分散染料橙的向列型液晶E7的性质以及碳纳米粒子(单壁碳纳米管或富勒烯C60)的影响. 两种分散染料橙11和13具有较高的溶解度和有序参数,被作为掺杂剂同时使用. 与掺杂单染料相比,同时加入两种染料橙使液晶的有序参数明显提高. 与纯液晶相比,掺杂可引起向列相向各向同性相转变温度的升高. 相似文献
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P. Kopčanský M. Koneracká I. Potočov´ M. Timko L. Tomčo J. Jadżyn G. Czechovski 《Czechoslovak Journal of Physics》2001,51(1):59-64
The stable ferronematics and ferrosmectics (combination of liquid crystals with fine magnetic particles) were prepared for 8CB liquid crystal and magnetc particles 11 nm in diameter. The structural transitions i.e. magnetic Fredericksz transition were indicated by means of dielectric and conductivity measurements.The experimental results i.e. the proof of initial condition
(
is director of LC molecules and
is magnetic moment of particles) and the increase of the threshold field of Fredericksz transition vs volume conduction of magnetic particles are in qualitative agreement with the Burylov and Raikher theory of thermotropic ferronematics. 相似文献
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Journal of Experimental and Theoretical Physics - The structural transformations in a nematic liquid crystal (NLC) layer with a hybrid orientation (planar director orientation is created on one... 相似文献
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当外磁场强度比较小时,液晶不会发生Freedericksz转变.利用介电张量分析了扭曲型向列液晶在弱磁场中的旋光效应.通过理论分析表明,线性偏振光经过磁场中的扭曲型向列液晶,会产生左右两束椭圆偏振光.这两束椭圆偏振光在该液晶中的传播速度不同,导致光经过液晶盒后光电场振动面发生偏转.进一步分析表明,对于同一种波长的光,磁场强度越大,其电场振动面旋转角度越大.在相同的磁场强度下,光波长越短,其电场振动面旋转角度越大.如果加上高的偏置电压,使向列型液晶分子长轴方向与外磁场方向平行,线性偏振光经过磁场中的该扭曲型向列液晶,其振动面会也发生偏转. 相似文献
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In the light of φ-mapping method and topological current theory, the stability of disclinations
around a spherical particle in nematic liquid crystals is studied.
We consider two different defect structures around a spherical
particle: disclination ring and point defect at the north or south
pole of the particle. We calculate the free energy of these different defects in the elastic theory. It is pointed out that the total Frank free energy density can be divided into two parts.
One is the distorted energy density of director field around the
disclinations. The other is the free energy density of disclinations themselves, which is shown to be concentrated at the defect and to be topologically quantized in the unit of
(k-k24)π/2. It is shown that in the presence of
saddle-splay elasticity a dipole (radial and hyperbolic hedgehog)
configuration that accompanies a particle with strong homeotropic
anchoring takes the structure of a small disclination ring, not a point defect. 相似文献
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We study the propagation of spatial solitons in nematic liquid crystals, using the self-similar method. Analytical solutions in the form of self-similar solitons are obtained exactly. We confirm the stability of these solutions by direct numerical simulation, and find that the stable spatial solitons can exist in various forms, such as Oaussian solitons, radially symmetric solitons, multipole solitons, and soliton vortices. 相似文献
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双轴向列相液晶的Monte Carlo模拟 总被引:1,自引:0,他引:1
利用Monte Carlo方法模拟棒状液晶分子随温度变化的相变行为,采用热力学统计方法得到能量与温度的关系,得出比热随温度的变化规律,通过图像的峰值确定相变点;重点模拟计算序参数矩阵元与温度的关系,得到不同分子结构参数下液晶系统的温度相图,模拟结果显示,当两个短棒长度相等时,不存在双轴相. 相似文献
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Giovanna Guidone Peroli Epifanio G. Virga 《Communications in Mathematical Physics》1999,200(1):195-210
A topological dipole is a pair of point defects with opposite topological charges. In this paper we show by example how the nucleation of such
a dipole within a smooth field can drive a metastable state into a stable one. Building on our previous work, we construct
a mathematical model for the dynamics of both monopoles and dipoles in a capillary filled with a nematic liquid crystal. Though
our analysis is fit for liquid crystals, a similar mechanism is also likely to apply to the field theory for other ordered
media.
Received: 10 July 1997 / Accepted: 25 June 1998 相似文献
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To study the nonlinear phenomena in rod-like magnetic liquid crystals (RMLCs), this paper establishes the dynamic model of molecular motion when giving a twisting disturbance to the molecules under external magnetic field. We find the twist of the molecules under magnetic field can be propagated in the form of a traveling wave. The dynamic equation of the molecular twisting we derived satisfies the form of Sine-Gordon equation. We obtain two solutions of the Sine-Gordon equation by theoretical calculation: the kink and anti-kink solitons and breathers. The characteristics of those solitons and breathers are discussed. 相似文献
14.
C60掺杂向列相液晶薄膜的激光诱导自衍射现象研究 总被引:1,自引:1,他引:0
利用Kirchhoff-Fraunhofer衍射积分原理研究了实验中观察到的C60掺杂垂直排列向列相液晶(5CB)液晶薄膜的远场衍射图样.模拟计算结果表明:实验中观察到的衍射圆环是不同实验参数的结果,并给出了确定衍射圆环结构的主要参数C1和C2.当C1和C2的符号相同时,远场会出现中心强度最大,向外逐渐减弱,分布尺度较小的细衍射环;当C1和C2的符号相反时,远场会出现中央较暗,向外逐渐增强,分布尺度较大的粗衍射环.衍射圆环的产生可由高斯光束通过非线性样品是引起附加相位的自相位调制现象来解释.将使液晶材料应用于光限幅等光子学领域. 相似文献
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An improved discussion on the dynamics of the Freedericksz transition in nematics is proposed. It is pointed out that the relaxation time γ-1 of the directors follows, an a2(a - 1) law in the twist deformation case. The possible chaotic motion of the directors in an external field ia briefly discussed. 相似文献
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E. S. Batyrshin A. P. Krekhov O. A. Skaldin 《Journal of Experimental and Theoretical Physics》2018,127(3):558-565
The forced phase locking in a system of the oscillating electroconvective rolls that form in a nematic liquid crystal layer in a dc electric field is studied. As a result of the action of an additive ac electric field with a small amplitude, the system of oscillators is found to be divided into clusters, where oscillations are fully phase locked. The electroconvective rolls in neighboring clusters oscillate in antiphase and the clusters are separated by Ising walls. The phase locking is shown to be maximal at the forcing frequency that is close to the double frequency of the natural oscillations of rolls. A model is proposed to describe spatially distributed phase oscillators, and it takes into account the symmetries of a system of electroconvective rolls and external forcing. The results of numerical simulations agree well with the experimental data. 相似文献
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ZHONG Xiaoxia WU Jiada CHEN Shuchao WU Changzheng LI Fuming 《Chinese Journal of Lasers》1997,6(5):403-408
1.IntroductionOpticalphaseconjugationhasbeeninvestigatedextensivelybecauseofitswideapplicationsinimagingtechnology,phase--conjugationlasers,andopticalassociativememorysystems.Notedfortheirlargeopticalreorientationnonlinearities[IJ,nematicliquidcrystals(NLC)havebecomepromisingopticalmediaforapplicationsinthefieldofnonlinearopticsincludingnonlinearphaseconjugation.In1980,Feketectal.[2)firstrealizedphase--conjugationbydegeneratefour--wavemixing(DFWM)inNLCintheisotropicphase.Sincethen,thefie… 相似文献
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L. C. Cortés-Cuautli G. F. Torres del Castillo 《International Journal of Theoretical Physics》2006,45(9):1783-1790
It is shown that, in the standard framework of non-relativistic quantum mechanics, the presence of a magnetic field implies that there are no operators representing those translations or rotations that do not leave invariant the magnetic field, and the corresponding components of the linear or angular momentum are undefined.
Pacs: 03.65.-w. 02.20.-a 相似文献
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