On the numerical study of Frederick transition in nematic liquid crystals

Shoarinejad, S.; Shahzamanian, M. A.

doi:10.1016/j.molliq.2007.05.004

Cited by 12 publications

(9 citation statements)

References 14 publications

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“…This formula contains both the conventional Fredericks transition behavior, [14][15], due to the dielectric torques, and the polarization Fredericks effect due to the ferroelectric torques. Obviously, at E = E th the Fredericks transition is induced by forcing the polarization and the director to reorient everywhere except at the slab boundaries.…”

Section: Fredericks Transition In a Pure Ssflcmentioning

confidence: 99%

Fredericks Transition in Pure and Nanodoped Surface Stabilized Ferroelectric Liquid Crystals

Shoarinejad

Sadeghisahebzad

2015

Molecular Crystals and Liquid Crystals

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Recently, ferroelectric liquid crystals (FLCs) doped with nanoparticles have attracted a wide interest not only from a scientific but also from a practical point of view and there is continuously growing interest in the effects caused by doping the ferroelectric nanoparticles. Furthermore, the presence of external fields exhibits a very interesting transition, reported by recent experiments. In this work, we investigate the response of a surface stabilized ferroelectric liquid crystal (SSFLC) doped with ferroelectric nanoparticles to an applied electric field. We assume that the smectic layers consist of uniform planes with a fixed orientation and the system is free from dislocation of constant layer thickness due to nanoparticles. We obtain the threshold field of orientational transition and the maximum deviation of the polarization vectors for a pure and a doped SSFLC medium. Then, we discuss the Fredericks transtion of the system and formation of inhomogeneous texture. It is found that the ferroelectric nanoparticles have significant influences in ordering behavior of a SSFLC medium and the threshold fields are critically changed by doping nanoparticles in the SSFLC, which is fundamental to operation of many liquid crystal devices.

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Section: Fredericks Transition In a Pure Ssflcmentioning

confidence: 99%

Fredericks Transition in Pure and Nanodoped Surface Stabilized Ferroelectric Liquid Crystals

Shoarinejad

Sadeghisahebzad

2015

Molecular Crystals and Liquid Crystals

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“…This formula shows the magnitude of the distortions in the vicinity of instabilities due to the generalized Fredericks transition appeared in a confined SmC* liquid crystal with a bookshelf structure under simultaneous applied electric and magnetic fields. It expects that the polarization and orientational transition in this structure, continuously increases from zero at E = E th , H =H th , which is comparable to the conventional Fredericks transition in a nematic phase [27], and an inhomogeneous phase would be a stable configuration at E N E th , H N H th . However, one may note that in this structure, φ m represents the maximum value of the angle of c-director which is the azimuthal angle indicating the direction of tilt in the smectic layer planes, defined as a phase variable.…”

Section: Threshold Behavior Of a Pure Ssflc Systemmentioning

confidence: 72%

“…(7), no experimental results were reported. As in our previous discussions, these formulas contain both the conventional Fredericks transition behavior and the polarization Fredericks effect due to the ferroelectric torques [22,23,26,27]. As shown in Eq.…”

Section: Threshold Behavior Of a Pure Ssflc Systemmentioning

confidence: 86%

“…However, there are further effects and complexities due to the ferroelectricity property of the system. To determine the threshold fields, first we calculate the value of φ(y) at the critical field by minimizing the total free energy using the Euler-Lagrange equation for small deviation angles [22,27]. Then, after some mathematical manipulations we obtain the following expression…”

Section: Threshold Behavior Of a Pure Ssflc Systemmentioning

confidence: 99%

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Threshold properties of nanodoped surface stabilized ferroelectric liquid crystals under electric and magnetic fields

Shoarinejad

Sadeghisahebzad

2016

Journal of Molecular Liquids

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“…In the general case, it seems that detailed prediction in these complex systems requires a good deal of computation [38][39][40][41][42][43][44]. In the general case, it seems that detailed prediction in these complex systems requires a good deal of computation [38][39][40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

A perturbative approach to the backflow dynamics of nematic defects

Biscari

Sluckin

2011

Eur. J. Appl. Math

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Link to this article: http://journals.cambridge.org/abstract_S0956792510000343How to cite this article: PAOLO BISCARI and TIMOTHY J. SLUCKIN (2012). A perturbative approach to the backow dynamics of nematic defects.We present an asymptotic theory that includes in a perturbative expansion the coupling effects between the director dynamics and the velocity field in a nematic liquid crystal. Backflow effects are most significant in the presence of defect motion, since in this case the presence of a velocity field may strongly reduce the total energy dissipation and thus increase the defect velocity. As an example, we illustrate how backflow influences the speeds of opposite-charged defects.works develop free energies of weakly inhomogeneous nematics, from which all hints of singularities in the director field have been been excised. Likewise, Ericksen [8][9][10], and later Leslie [11], in their development of a consistent nematodynamics, suppose that the director is everywhere well defined, and develop stress tensor descriptions in terms of rates of change and inhomogeneities in the director and velocity fields.It was only later, after the theoretical structure of disclination-free nematics had been well understood, that defect problems once again became a primary focus of research. Key questions are, firstly, what is the molecular organisation in the core of a disclination line, and secondly, how does a disclination line (or assembly of lines) move in a nematic fluid. A subsidiary question, still open at the time of writing, concerns the extent to which details of the internal structure are important in determining defect motion.There are two basic strategies that have been adopted in order to understand defect motion and structure. On the one hand one can follow what elsewhere in material science is known as the phase field strategy. A phase field in the context of crystallization dynamics involves the introduction of an artificial order parameter describing the degree of crystallization. In so doing, one turns a difficult free boundary problem into a (relatively!) easy differential problem. In the context of nematic liquid crystals, the idea is to embed the Oseen-Frank-Leslie-Ericksen director picture minimally into a more general-order parameter picture. The relevant free energy was first written down by de Gennes [12] in terms of what was then known as the Saupe ordering matrix, but which is now known as the Q-tensor [13][14][15]. However, it is important to note that here the Q-tensor is a phase field with a real molecular meaning, unlike some phase fields used elsewhere. Under suitable conditions, the Q-tensor defines a single vector n ≡ −n, and then the macroscopic theories are valid. But in the core of the defect, it is no longer possible to define the director n. This was the strategy adopted by Schopohl and one of the authors long ago [16] when discussing the disclination core structure.An alternative route to dealing with defect cores in a domain where the director can otherwise be regularly defined is ...

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On the numerical study of Frederick transition in nematic liquid crystals

Cited by 12 publications

References 14 publications

Fredericks Transition in Pure and Nanodoped Surface Stabilized Ferroelectric Liquid Crystals

Fredericks Transition in Pure and Nanodoped Surface Stabilized Ferroelectric Liquid Crystals

Threshold properties of nanodoped surface stabilized ferroelectric liquid crystals under electric and magnetic fields

A perturbative approach to the backflow dynamics of nematic defects

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