Simple method for determination of twist elastic constants in tilted smectic liquid crystals

1993 ◽  
Author(s):  
Wojciech Kuczynski
Keyword(s):  
Liquid Crystals ◽  
Elastic Constants ◽  
Smectic Liquid Crystals ◽  
Simple Method

Numerical investigation of influence of ionic space charge and flexoelectric polarization on measurements of elastic constants in nematic liquid crystals

2009 ◽  
Vol 17 (2) ◽  
Author(s):  
M. Buczkowska ◽  
G. Derfel ◽  
M. Konowalski
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
External Magnetic Field ◽  
Space Charge ◽  
Elastic Constants ◽  
High Concentration ◽  
Light Passing ◽  
The Magnetic Field

AbstractDeformations of nematic layers caused by magnetic field allow determination of the elastic constants of liquid crystal. In this paper, we simulated numerically the deformations of planar and homeotropic nematic layers. The flexoelectric properties of the nematic and presence of ions were taken into account. Our aim was to show the influence of flexoelectricity on the results of the real measurement of the elastic constants k33 and k11. In these simulations, we calculated the optical phase difference ΔΦ between the ordinary and extraordinary rays of light passing through the layer placed between crossed polarizers as a function of the magnetic field induction B. One of the elastic constants can be calculated from the magnetic field threshold for deformation. The ratio k33/k11 can be found by means of fitting theoretical ΔΦ(B) dependence to the experimental results. The calculations reveal that the flexoelectric properties influence the deformations induced by the external magnetic field. In the case of highly pure samples, this may lead to false results of measurement of the elastic constants ratio k33/k11. This influence can be reduced if the nematic material contains ions of sufficiently high concentration. These results show that the flexoelectric properties may play an important role, especially in well purified samples.

Direct Determination of the Anisotropy of the Magnetic Susceptibility in Smectic Liquid Crystals

1985 ◽  
Vol 40 (1) ◽  
pp. 46-51 ◽  
Author(s):  
G. Illian ◽  
H. Kneppe ◽  
F. Schneider
Keyword(s):  
Magnetic Susceptibility ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Direct Determination ◽  
Oscillation Period ◽  
Smectic Liquid Crystals ◽  
Smectic Liquid Crystal ◽  
Smectic Phases ◽  
Phase Sequence

A sample of an aligned smectic liquid crystal, suspended in a magnetic field, can be excited to oscillations. Measurement of the oscillation period allows a direct determination of the anisotropy of the magnetic susceptibility. Liquid crystals exhibiting the phase sequence isotropicnematic- smectic A can be aligned very well and precise y.A values can be determined. A direct transformation from the isotropic to the smectic phase or phase transitions between smectic phases can cause an incomplete alignment of the liquid crystal and worse results.

The Determination of the Elastic Constants of Nematic Liquid Crystals

1976 ◽  
Vol 37 (1) ◽  
pp. 269-280 ◽  
Author(s):  
W. H. De Jeu ◽  
W. A. P. Claassen ◽  
A. M. J. Spruijt
Keyword(s):  
Liquid Crystals ◽  
Elastic Constants ◽  
Nematic Liquid Crystals

ChemInform Abstract: Simple Method for Confirming the Antiferroelectric Structure of Smectic Liquid Crystals.

ChemInform ◽  
2010 ◽  
Vol 23 (38) ◽  
pp. no-no
Author(s):  
Y. TAKANISHI ◽  
H. TAKEZOE ◽  
A. FUKUDA ◽  
H. KOMURA ◽  
J. WATANABE
Keyword(s):  
Liquid Crystals ◽  
Smectic Liquid Crystals ◽  
Simple Method

The Determination of Elastic Constants in Weakly Birefringent Liquid Crystals

1985 ◽  
pp. 415-422
Author(s):  
Donald B. Dupré ◽  
Jacob R. Fernandes
Keyword(s):  
Liquid Crystals ◽  
Elastic Constants

Automated determination of n-cyanobiphenyl and n-cyanobiphenyl binary mixtures elastic constants in the nematic phase from molecular simulation

2020 ◽  
Vol 5 (6) ◽  
pp. 1131-1136
Author(s):  
Jiale Shi ◽  
Hythem Sidky ◽  
Jonathan K. Whitmer
Keyword(s):  
Liquid Crystals ◽  
Molecular Simulation ◽  
Elastic Properties ◽  
Binary Mixtures ◽  
Elastic Constants ◽  
Nematic Phase ◽  
New Techniques ◽  
New Applications ◽  
Automated Determination

This work explores new techniques in molecular simulation which can be used to precisely determine and engineer elastic properties of liquid crystals for new applications.

Bestimmung elastischer Konstanten von MBBA und EBBA mit der elektrischen Leitfähigkeitsmethode / Determination of the Elastic Constants of MBBA and EBBA by Electric Conductivity Measurements

1975 ◽  
Vol 30 (4) ◽  
pp. 515-518 ◽  
Author(s):  
M. Greulich ◽  
G. Heppke ◽  
F. Schneider
Keyword(s):  
Magnetic Susceptibility ◽  
Liquid Crystals ◽  
Temperature Dependence ◽  
Electric Conductivity ◽  
Elastic Constants ◽  
Nematic Liquid Crystals ◽  
Elastic Behaviour ◽  
Conductivity Measurements

Abstract Several methods of studying the elastic behaviour of nematic liquid crystals by means of measuring the electric conductivity are discussed. The temperature dependence of the ratio of the splay and bend elastic constants to the anisotropy of the magnetic susceptibility is determined for N-(p-methoxybenzylidene) -p-n-butylaniline (MBBA), N-(p-ethoxybenzylidene) -p-n-butylaniline (EBBA) and mixtures of both.

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