scholarly journals Chiral Symmetry Breaking in Liquid Crystals: Appearance of Ferroelectricity and Antiferroelectricity

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1900
Author(s):  
Yoichi Takanishi
Keyword(s):  
Liquid Crystals ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Future Prospects ◽  
X Ray ◽  
X Ray Scattering ◽  
Ferroelectricity And Antiferroelectricity ◽  
Two Phases ◽  
Successive Phase

The study of chiral symmetry breaking in liquid crystals and the consequent emergence of ferroelectric and antiferroelectric phases is described. Furthermore, we show that the frustration between two phases induces a variety of structural phases called subphases and that resonant X-ray scattering is a powerful tool for the structural analysis of these complicated subphases. Finally, we discuss the future prospects for clarifying the origin of such successive phase transition.

scholarly journals Symmetry and symmetry breaking during crystal growth

2014 ◽  
Vol 70 (a1) ◽  
pp. C940-C940
Author(s):  
Elias Vlieg
Keyword(s):  
Crystal Growth ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chiral Compounds ◽  
Isomorphous Replacement ◽  
Muscovite Mica ◽  
Left And Right

Two cases of symmetry and its breaking will be discussed in the context of crystal growth: chirality and surfaces. Chiral symmetry is a particularly interesting form of symmetry in crystal growth that may even be directly related to the homochirality that is found in Nature. About 10% of the chiral compounds crystallize as so-called racemic conglomerates, i.e. as separate crystals with only left or only right-handed molecules. The first experiments of Pasteur on a tartaric acid salt were an example of this. When crystallizing such compounds, one would expect a (symmetric) 50:50 mixture of both types of crystals, but often this is not the case. We will discuss (1) the chiral symmetry breaking in such systems [1], (2) the formation of epitaxial conglomerates that partially hide the true symmetry and (3) a phase transition from a racemic crystal (with both left- and right-handed molecules in the unit cell) to a racemic conglomerate. X-ray diffraction is often insufficient to fully characterize such systems, and solid-state NMR and computer simulations yield important additional insights. The symmetry of a bulk crystal is by definition broken at its surface, and this can manifest itself in different ways. Muscovite mica, as an example, can be made extremely flat by cleaving and therefore the bulk glide plane symmetry can be lost at the surface [2]. Charge neutrality dictates the distribution of the ions at the surface of mica and seems to be determined by local variations in the Al/Si ratio that are invisible for X-ray diffraction. By isomorphous replacement of the topmost K ions, mica can be functionalized to specifically react with other compounds.

scholarly journals Local chiral symmetry breaking in triatic liquid crystals

2012 ◽  
Vol 3 (1) ◽  
Author(s):  
Kun Zhao ◽  
Robijn Bruinsma ◽  
Thomas G. Mason
Keyword(s):  
Liquid Crystals ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking

scholarly journals Chiral symmetry breaking in bent-core liquid crystals

2009 ◽  
Vol 79 (4) ◽  
Author(s):  
Lech Longa ◽  
Grzegorz Pająk ◽  
Thomas Wydro
Keyword(s):  
Liquid Crystals ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking

scholarly journals Chiral structures from achiral liquid crystals in cylindrical capillaries

2015 ◽  
Vol 112 (15) ◽  
pp. E1837-E1844 ◽  
Author(s):  
Joonwoo Jeong ◽  
Louis Kang ◽  
Zoey S. Davidson ◽  
Peter J. Collings ◽  
Tom C. Lubensky ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Elastic Anisotropy ◽  
Double Helix ◽  
Chiral Symmetry Breaking ◽  
Sunset Yellow ◽  
Chiral Structures ◽  
Simple Boundary ◽  
Cylindrical Axis

We study chiral symmetry-broken configurations of nematic liquid crystals (LCs) confined to cylindrical capillaries with homeotropic anchoring on the cylinder walls (i.e., perpendicular surface alignment). Interestingly, achiral nematic LCs with comparatively small twist elastic moduli relieve bend and splay deformations by introducing twist deformations. In the resulting twisted and escaped radial (TER) configuration, LC directors are parallel to the cylindrical axis near the center, but to attain radial orientation near the capillary wall, they escape along the radius through bend and twist distortions. Chiral symmetry-breaking experiments in polymer-coated capillaries are carried out using Sunset Yellow FCF, a lyotropic chromonic LC with a small twist elastic constant. Its director configurations are investigated by polarized optical microscopy and explained theoretically with numerical calculations. A rich phenomenology of defects also arises from the degenerate bend/twist deformations of the TER configuration, including a nonsingular domain wall separating domains of opposite twist handedness but the same escape direction and singular point defects (hedgehogs) separating domains of opposite escape direction. We show the energetic preference for singular defects separating domains of opposite twist handedness compared with those of the same handedness, and we report remarkable chiral configurations with a double helix of disclination lines along the cylindrical axis. These findings show archetypally how simple boundary conditions and elastic anisotropy of confined materials lead to multiple symmetry breaking and how these broken symmetries combine to create a variety of defects.

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