Smectic-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>A</mml:mi></mml:mrow><mml:mrow><mml:mi>*</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>–smectic-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mi>*</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>transition in a ferroelectric liquid crystal without smectic layer shrinkage

Gießelmann, Frank; Zugenmaier, P.; Dierking, Ingo; Lagerwall, S. T.; Stebler, B.; Kašpar, Miroslav; Hamplová, Věra; Glogarová, Milada

doi:10.1103/physreve.60.598

Cited by 94 publications

(80 citation statements)

References 21 publications

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“…In the latter case the magnitude of electroclinic coefficient is more because the tilt does not have to resist layer compression. 3,8 These de Vries ELCs do not possess a long-range order of the direction of tilt. In the Sm-A phase, i.e., above the critical temperature T c the molecular tilting direction is disordered with an azimuthal angle varying from 0 to 2 on the de Vries cone.…”

Section: A Tilt and Textural Study Of Electroclinic And Ferroelectrimentioning

confidence: 99%

“…The tilted Sm-C * like smectic layers of Sm-A are stacked randomly, i.e., the molecules are tilted with respect to the smectic layer normal, similar to those in the Sm-C * phase but the tilt direction in different smectic layers are randomly oriented. In such materials tilt is not accompanied by layer stress, 3,12 due to which the value of electroclinic coefficient is more. In general, electroclinic effect is observed in both orthogonal as well as tilted Sm-A phase but there is an inherent characteristic difference between these two cases.…”

Section: Introductionmentioning

confidence: 99%

“…3 Later on it was found that the electroclinic effect could also be possible in tilted Sm-A phase in which although the molecules are tilted in Sm-A phase but the individual layer polarization is zero due to randomization of tilt in each layer. [4][5][6][7][8] These are the de Vries liquid crystals reported by Diele et al, 9 and later explained by de Vries in 1974.…”

Section: Introductionmentioning

confidence: 99%

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A dielectric mode in electroclinic liquid crystals

Thakur

Choudhary

Kaur

et al. 2006

Journal of Applied Physics

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The dielectric properties of electroclinic and ferroelectric liquid crystal materials have been investigated in the frequency range of 100 Hz-10 MHz. A dielectric mode has been predicted in electroclinic liquid crystals near the transition temperature of Sm-C * -Sm-A phase. It has been observed that the investigated material has nonlayer shrinkage near the transition temperature of Sm-C * -Sm-A phase and shows anomalous behavior of dielectric spectra, tilt, and texture which is entirely different from the behavior of ferroelectric liquid crystals ͑FLCs͒. The dielectric relaxation frequency and tilt angle are almost constant with respect to temperature near the transition temperature under high bias field, which is characteristically different from FLCs. The high dielectric permittivity near T c owing to the presence of mode contribution leads to the fact that there is an intralayer phason variation few degrees before transition. The mode has been named random mode due to its origin from randomization of tilt near T c . Tilt randomization has been considered as an order parameter because in both the phases molecules are tilted but it is disordered in Sm-A phase making its intralayer polarization zero.

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Section: A Tilt and Textural Study Of Electroclinic And Ferroelectrimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A dielectric mode in electroclinic liquid crystals

Thakur

Choudhary

Kaur

et al. 2006

Journal of Applied Physics

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“…We assume that α, b and c are temperature independent. In this model we will also assume an empirically derived relationship [7] between the layer tilt and the cone angle, δ = µθ, where |µ| = 0.85 is a typical experimentally determined value [7,8]. Therefore, we will model C1 and C2 chevrons by assuming µ = +0.85 and µ = −0.85 respectively, when θ > 0.…”

Section: Energymentioning

confidence: 99%

Effects of Weak Anchoring on C1 and C2 Chevron Structures

Diaz

McKay

Mottram

2005

Molecular Crystals and Liquid Crystals

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This version is available at https://strathprints.strath.ac.uk/2227/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. We present a theoretical study of the effect of weak anchoring on the transition between C1 and C2 chevron structures in smectic C liquid crystals. We employ a continuum theory which allows for variable cone, azimuthal and layer tilt angles. Equilibrium profiles for the director cone and azimuthal angles in the C1 and C2 states are calculated from the standard Euler-Lagrange minimisation of the total energy of the system. By comparing the total energies of the C1 and C2 states we can determine the globally stable chevron profile and calculate the critical temperature for the C1-C2 transition, which depends on anchoring strength and pretilt angle variations. EFFECTS OF WEAK ANCHORING ON C1 AND C2 CHEVRON STRUCTURESKeywords: surface-stabilised ferroelectric liquid crystals; weak anchoring; C1, C2 structure formation. INTRODUCTIONClark and Lagerwall first demonstrated the surface stabilisation of ferroelectric liquid crystals (SSFLCs) in 1980 [1] and demonstrated that it was possible to suppress the chiral helix by confining a smectic C * material between two parallel substrates. It was soon realised that an understanding of the chevron structure of the smectic layers [2-4] was crucial to exploiting the display possibilities of SSFLCs. Since then a great deal of research has focused on the development of SSFLCs for display purposes. The chevron structure appears when a sample of smectic A, in a bookshelf configuration, when the liquid crystal is cooled to the smectic C phase. The layer contraction that occurs during cooling is associated with a layer lengthening and thus, in a constrained system where layer continuity is conserved, layer buckling. This buckling may be degenerate so that there are two possible directions for the layer to orientate, leading to C1 and C2 chevrons (see fig. 1). This degeneracy of the laye...

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“…[2][3][4][5] Among all FLCs, a special class of FLC with considerably wide range of SmA ‫ء‬ phase and a large electroclinic coefficient, is very interesting 6,7 due to its ultra fast response and nonlayer shrinkage. [8][9][10][11][12] These FLCs are known as electroclinic LCs ͑ELCs͒.…”

Section: Introductionmentioning

confidence: 99%

Effect of graphene oxide nanomaterial in electroclinic liquid crystals

Malik

Choudhary

Silotia

et al. 2010

Journal of Applied Physics

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The collective dielectric relaxation studies have been carried out on the electroclinic liquid crystals ͑ELCs͒ doped with 0.1 to 0.2 wt % of graphene oxide ͑GO͒ in the frequency range of 20 Hz to 1 MHz. The GO favors for a good quality vertical alignment without any surface treatment of the substrates. The coupling of GO with indium tin oxide ͑ITO͒ substrate and ELC materials affects the molecular ordering and supports the ELC molecules to be aligned along the GO attached to the ITO surface in vertical direction. The vertical alignment can be changed to homogeneous by applying a high bias field to the sample and such converted homogeneous cell shows an additional dielectric relaxation peak in the low frequency side of Goldstone mode in SmC ‫ء‬ phase due to presence of GO whereas in the pure material no such peak was observed. The frequency separation of both peaks ͑Goldstone mode and an additional peak͒ increases with temperature and low frequency peak vanishes near transition temperature.

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Smectic-A–smectic-Ctransition in a ferroelectric liquid crystal without smectic layer shrinkage

Cited by 94 publications

References 21 publications

A dielectric mode in electroclinic liquid crystals

A dielectric mode in electroclinic liquid crystals

Effects of Weak Anchoring on C1 and C2 Chevron Structures

Effect of graphene oxide nanomaterial in electroclinic liquid crystals

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Smectic-A*–smectic-C*transition in a ferroelectric liquid crystal without smectic layer shrinkage

Cited by 94 publications

References 21 publications

A dielectric mode in electroclinic liquid crystals

A dielectric mode in electroclinic liquid crystals

Effects of Weak Anchoring on C1 and C2 Chevron Structures

Effect of graphene oxide nanomaterial in electroclinic liquid crystals

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Product

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Smectic-A–smectic-Ctransition in a ferroelectric liquid crystal without smectic layer shrinkage