Dynamics of dislocations in the domain structure of the nematic liquid crystal

2020 ◽  
Vol 15 (3-4) ◽  
pp. 201-207
Author(s):  
V.A. Delev
Keyword(s):  
Liquid Crystal ◽  
Domain Structure ◽  
Nematic Liquid Crystal ◽  
Gordon Equation ◽  
Tangential Component ◽  
Axial Component ◽  
Sine Gordon Equation ◽  
Topological Charges

Dynamics and interaction of classical dislocations in the domain structure of π/2 nematic liquid crystal is studied. A feature of twisted nematics is that hydrodynamic flows in Williams domains, together with the tangential component of velocity, also have an axial component, the direction of which is opposite in neighboring domains. Dislocations can move both perpendicular (glide) to Williams domains, and along (climb) them. It was found that when dislocations collide with opposite topological charges S = ±1 at given voltage, their speed increases. It has been shown that dynamics and interaction of dislocations with topological charges S = ±1 are qualitatively well described by the perturbed sine-Gordon equation.

Visualization of domain structure of a weak ferroelectric Li2Ge7O15by nematic liquid crystal method

1991 ◽  
Vol 13 (4) ◽  
pp. 81-84 ◽  
Author(s):  
N. A. Tikhomirova ◽  
A. V. Ginzberg ◽  
S. P. Chumakova ◽  
M. D. Volnyanskii ◽  
M. Polonska ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Domain Structure ◽  
Nematic Liquid Crystal

Optical properties of nematic liquid crystal (C21H27NO2S) under AC/DC electric fields

2009 ◽  
Vol 87 (4) ◽  
pp. 293-298 ◽  
Author(s):  
Mehriban Emek ◽  
Nurettin Besli ◽  
Ahmet Yildirim ◽  
Suleyman Yilmaz
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Electric Field ◽  
Domain Structure ◽  
Nematic Liquid Crystal ◽  
Electric Fields ◽  
Transition Process ◽  
Optical Methods ◽  
Rotational Angle ◽  
Dc Electric Fields

In this study, the effects of the phase transition on the optical transmittance of the nematic liquid crystal C21H27NO2S, 4′-isothiocyanatophenyl-4-pentylbicyclo[2,2,2]octane-1-carboxylate are investigated in terms of temperature variation and rotational angle of the polarizer through electro-optical methods under AC / DC electric fields. It is observed that the domain structure of the material is affected considerably by the applied electric field as the temperature changes. Under applied electric fields, the crystal-nematic (CN) phase-transition point changes and the behaviour of the liquid crystal in the phase-transition region shows some differences. The intensity of the light passing through the system under a DC electric field increases as the electric field rises. Nevertheless, the intensity of the transmitted light under an AC electric field increases at the beginning and then decreases as the electric field rises to a temperature of more than 355 K. These results can be explained through the formation of a domain structure during the phase-transition process and the light scattering caused by these structures.

Field-induced effects in an eutectic nematic liquid crystal mixture

2003 ◽  
Vol 81 (12) ◽  
pp. 1427-1432 ◽  
Author(s):  
A K Gathania ◽  
K K Raina
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Work Function ◽  
Domain Structure ◽  
Nematic Liquid Crystal ◽  
Threshold Field ◽  
Electric Field Effects ◽  
Dc Electric Field ◽  
Substrate Surfaces ◽  
Crystal Mixture

Electric-field effects were investigated in a planar-aligned nematic liquid crystal mixture. Under a DC electric field, we observed the presence of domains. The domain structure changed near the threshold field. The effects of charge injection from the substrate surfaces were investigated. The work function is calculated using Richardson's equation.PACS No.: 61.30.Hn

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