Thresholdless Switching in Homogeneous Cells and Antiferroelectric Conoscopic Figures in Free-Standing Films as Observed in A Binary SC*-Like Mixture

Seomun, San‐Seong; Takanishi, Yoichi; Ishikawa, Ken; Takezoe, Hideo; Fukuda, Atsuo; Tanaka, C.; Fujiyama, Toshiaki; Maruyama, Tadaaki; Nishiyama, Shinichi

doi:10.1080/10587259708039423

Cited by 30 publications

(9 citation statements)

References 10 publications

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“…[43] and Figure 2 of Ref. [45]. The increase of the smectic layer spacing with lowering temperature not only in SmC Ã A but also in SmC Ã has been observed in several compounds and mixtures, although detailed study has not been carried out as yet.…”

Section: Liquid Crystals 873mentioning

confidence: 90%

“…[44] and identified HxI Ã , which must be ferroelectric modulated HxB because of the characteristic temperature dependence of the smectic layer spacing as given in Figure 2 of Ref. [45]. It should be noted that in systems where HxB is completely absent, the SmC Ã -HxI Ã transition can simply be induced by temperature change and an electric-fieldinduced switching via four states was actually observed, which is characteristic of ferroelectric HxI Ã .…”

Section: Liquid Crystals 871mentioning

confidence: 94%

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Renewed focus on the small temperature change of smectic layer spacing in ferroelectric and antiferroelectric LCs

et al. 2015

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We aim at becoming released from the invisible hand of de Vries scenario that a small temperature change in the smectic layer spacing must be caused by 'the far-fetched orientational distribution called the de Vries diffused cone' or 'the in-layer directors statically tilted and randomly distributed around the smectic layer normal'. First, we show in a prototypal compound MC513 that all the unusual properties suggesting the revival of a de Vries-type SmA-SmC Ã transition can be explained by ordinary SmA emergence just below the isotropic phase only in a narrow temperature range. Second, we take up the unconventional molecular structure of TSiKN65, thus far regarded as a typical de Vries material; the core part makes a large angle of β c ,30 with respect to the average molecular long axis. We insist that a slight change in β c can explain almost all the unusual properties without taking account of the de Vries scenario. Last but not least is a practical point of view. During a thermal shock cyclic reliability test between −20°C and 60°C in prototyping antiferroelectric liquid crystal displays (AFLCDs), DENSO noticed the importance of the transition from SmC Ã A to the hexatic or crystalline phase; the cell quality critically depends on the layer spacing change in the lower-temperature part of SmC Ã A . We point out that the relative displacements of molecules along their long axes and hence the layer undulational fluctuations play an important role in addition to the director tilting ones.

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Section: Liquid Crystals 873mentioning

confidence: 90%

Section: Liquid Crystals 871mentioning

confidence: 94%

Renewed focus on the small temperature change of smectic layer spacing in ferroelectric and antiferroelectric LCs

et al. 2015

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“…However, up till now no clear experimental evidences of 226 W. Piecek et al such a phase have been observed. In contrary, Seomun et al [13] have proposed that the tilting randomization due to breaking of the intrinsic inter-layer correlation, resulting in the V-shaped switching.…”

Section: Introductionmentioning

confidence: 96%

A Study of a Binary Liquid-Crystalline Mixtures with the Wide Antiferroelectric Phase

et al. 2006

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Binary mixtures of fluorinated materials having broad antiferroelectric phase have been prepared. A set of phase parameters (phase transition temperatures and enthalpies, the spontaneous polarization and the tilt angle) of pure antiferroelectric components and mixtures prepared using them have been studied. Electrooptical investigations of obtained mixtures have been conducted. An influence of mole mixing ratio of two components on evolution of electrooptical switching from tristable through V-shaped to W-shaped characteristics has been observed. The thresholdless switching of a mixture with specific mixing ratio has been ascribed as the result of the formation of frustrated phase in the medium.

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“…Two models can be found in the literature, which explain the effect of V-shaped switching. Japanese group [2] proposed the model of "random smectic C-like" phase. They assumed that correlation between tilt directions in adjacent smectic layers is very weak.…”

Section: Introductionmentioning

confidence: 99%

“…V=1_exp-(k.t)"} (2) where t denotes time, k -a constant being a measure of the transition rate and d -a constant dependent on the dimensionality ofthe transition process. Solid lines in Fig.…”

mentioning

confidence: 99%

Polarization reversal in antiferroelectric liquid crystals

Goc

Kuczyński

2002

XIV Conference on Liquid Crystals: Chemistry, Physics, and Applications

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We studied the change in polarization direction during field reversal in binary mixtures possessing antiferroelectric phase. Due to the coupling ofthe electric field with the spontaneous polarization of each smectic layer, the transition from antiferroelectric to the ferroelectric phase was induced. This transition was accompanied by changes in optical properties. Both three-state and V-shaped switching was observed. After removing the field, the sample transformed back to the antiferroelectric state. We have found that in some cases, the kinetics of this transition was very slow -its time constant ranged from minutes to days, depending on temperature. In the same mixtures, we observed a large thermal hysteresis of the phase transition between the ferroelectric and antiferroelectric phases. We argue that all three phenomena: V-shaped switching, slow kinetics and thermal hysteresis have the same origin. They occur, when the ferroelectric and antiferroelectric interactions acting between smectic layers are of comparable strength. We compare our results with the existing models ofV-shaped switching and propose a modification ofthe models.

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Thresholdless Switching in Homogeneous Cells and Antiferroelectric Conoscopic Figures in Free-Standing Films as Observed in A Binary SC*-Like Mixture

Cited by 30 publications

References 10 publications

Renewed focus on the small temperature change of smectic layer spacing in ferroelectric and antiferroelectric LCs

Renewed focus on the small temperature change of smectic layer spacing in ferroelectric and antiferroelectric LCs

A Study of a Binary Liquid-Crystalline Mixtures with the Wide Antiferroelectric Phase

Polarization reversal in antiferroelectric liquid crystals

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