Smectic Liquid Crystals: Antiferroelectric and Ferrielectric Phases

Takezoe, Hideo; Takanishi, Yoichi

doi:10.1007/0-387-21642-1_9

Cited by 9 publications

(6 citation statements)

References 95 publications

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“…A small amount (about of 0.1∼0.2% of the KBr amount) of CBDA and DABP which are powder were mixed with KBr [9]. To measure properties of liquid crystal cell, the polar diagrams were made by UV-visible spectrometer [10]. From these measurements of alignment properties of polyimide, the dichroic ratio(R) is calculated from the Maier-Saupe theory [11].…”

Section: Measurementsmentioning

confidence: 99%

Photo-Alignment Using Benzophenone Sensitized Photodecomposition of the Polyimide

Yang

Shin

2014

Molecular Crystals and Liquid Crystals

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For more aggressive photo-decomposition of polyimide, the photoreactions employing triplet mechanism and the double fragmentation reactions were carried out. The polyimide was synthesized with cyclobutane-1, 2, 3, 4-tetracarboxylic dianhydride (CBDA) and 4, 4 -diaminobenzophenone (DABP) by condensation reaction. The benzophenone is well known triplet photo sensitizer, which was mixed with the equal mole ratio of the CBDA, The imidization reaction was confirmed by imide peak formation in FT-IR spectra. The orientation of polymer chains was confirmed by polar dichroic ratio of the liquid crystal cells. The benzophenone chromospheres shortened the UV irradiation time for the photodecomposition and induced the orientation of the polyimide chains.

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Section: Measurementsmentioning

confidence: 99%

Photo-Alignment Using Benzophenone Sensitized Photodecomposition of the Polyimide

Yang

Shin

2014

Molecular Crystals and Liquid Crystals

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“…The liquid crystalline materials exhibit the richest variety of polymorphism [1][2][3][4][5][6][7]. Very rich experimental data are available for the thermodynamic and transition properties of the achiral as well as the chiral mesophases.…”

Section: Phase Transitions Involving Ferroelectric Smectic C Phasesmentioning

confidence: 99%

“…For last two decades, the study of ferroelectric chiral smectic liquid crystals [1][2][3][4][5][6][7] has been an active area of considerable research interest in condensed matter and statistical mechanics. Much effort has been devoted to investigate the behaviour of helicoidal chiral smectic C (Sm C*) phase from the fundamental understanding as well as potential applications [8][9][10] point of view.…”

Section: Introductionmentioning

confidence: 99%

Phase transitions in ferroelectric liquid crystals

2008

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“…All three phases may appear directly below the nontilted SmA phase. Experimentally three different phase diagrams have been observed [12], which are presented schematically in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…It was generally believed that the number of phases increases with increasing the optical purity. However, recent experiments [12,13] has shown that in some systems the opposite is true, i.e. the number of phases is reduced if the optical purity is extremely high.…”

Section: Introductionmentioning

confidence: 99%

Effect of optical purity on phase sequence in antiferroelectric liquid crystals

Vaupotič

Čepič

2005

Phys. Rev. E

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We use the discrete phenomenological model to study theoretically the phase diagrams in antiferroelectric liquid crystals (AFLCs) as a function of optical purity and temperature. Recent experiments have shown that in some systems the number of phases is reduced if the optical purity is extremely high. In some materials the SmC ⋆ A phase is the only stable tilted smectic phase in the pure sample. In the scope of the presented model this high sensitivity of the phase sequence in the AFLCs to optical purity is attributed to the piezoelectric coupling which is reduced if optical purity is reduced. We limit our study to three topologically equal phases -SmC * , SmC * α and SmC * A and show that the reduction of optical purity forces the system from the antiferroelectric to the ferroelectric phase with a possible SmC ⋆ α between them. The effect of the flexoelectric and quadrupolar coupling is considered as well. If the phase diagram includes only two phases, SmC ⋆ and SmC ⋆ A , the flexoelectric coupling is very small. The materials which exhibit the SmC ⋆ α in a certain range of optical purity and temperature, can be expected to have a significant flexoelectric coupling that is comparable with the piezoelectric coupling. And finally, when temperature is lowered the phase sequence SmA → SmC ⋆ α → SmC ⋆ → SmC ⋆ A is possible only in materials in which quadrupolar coupling is very strong.

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Smectic Liquid Crystals: Antiferroelectric and Ferrielectric Phases

Cited by 9 publications

References 95 publications

Photo-Alignment Using Benzophenone Sensitized Photodecomposition of the Polyimide

Photo-Alignment Using Benzophenone Sensitized Photodecomposition of the Polyimide

Phase transitions in ferroelectric liquid crystals

Effect of optical purity on phase sequence in antiferroelectric liquid crystals

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