Layered anisotropic liquids: deformation of structures in electric and magnetic fields

2017 ◽  
Vol 12 (2) ◽  
pp. 214-218
Author(s):  
N.G. Migranov ◽  
D.V. Kondratyev
Keyword(s):  
Free Energy ◽  
Liquid Crystal ◽  
Magnetic Fields ◽  
Continuum Model ◽  
Polar Angle ◽  
Unit Vector ◽  
Ferroelectric Liquid Crystal ◽  
Anisotropic Layer ◽  
Electric And Magnetic Fields

On the basis of the analysis of the free energy of a viscoelastic anisotropic layer liquid, a chiral ferroelectric liquid crystal C^∗ , located in a thin cell in a ”bookshelf“ geometry the possibility of the smectic layers periodic distortions in the external magnetic H and electric E fields applied perpendicularly and along the plates, respectively, are investigated. The polar angle θ formed by the unit vector n and the normal a to the smectic planes is fixed, and the appearing Helfrich–Yuro distortions u of the smectic layers are assumed to be small in the proposed continuum model of the liquid ferroelectrics.

scholarly journals Sensitivity of 6CHBT Liquid Crystal Doped with Ferroelectric or Magnetic Particles to Electric and Magnetic Fields

2014 ◽  
Vol 126 (1) ◽  
pp. 260-261 ◽  
Author(s):  
J. Majorošová ◽  
N. Tomašovičová ◽  
M. Timko ◽  
M. Koneracká ◽  
I.P. Studenyak ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Electric And Magnetic Fields

Phase Transitions in Liquid Crystal Doped with Magnetic Particles of Different Shapes in Combined Electric and Magnetic Fields

2014 ◽  
Vol 35 (11) ◽  
pp. 2044-2053 ◽  
Author(s):  
Natália Tomašovičová ◽  
Milan Timko ◽  
Vlasta Závišová ◽  
Anežka Hashim ◽  
Jan Jadzyn ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Liquid Crystal ◽  
Magnetic Fields ◽  
Magnetic Particles ◽  
Electric And Magnetic Fields ◽  
Different Shapes

Influence of Piezoelectric Bilinear and Biquadratic Coupling in Smectic C* Phase of Ferroelectric Liquid Crystal

1997 ◽  
Vol 11 (29) ◽  
pp. 3491-3502 ◽  
Author(s):  
Susanta Sinha Roy ◽  
Subir Kumar Roy ◽  
Prabir K. Mukherjee
Keyword(s):  
Phase Transition ◽  
Free Energy ◽  
Liquid Crystal ◽  
Transition Temperature ◽  
Order Parameter ◽  
Ferroelectric Liquid Crystal ◽  
Coupling Constant ◽  
Theoretical Relation ◽  
Smectic C ◽  
Quadrupolar Order

A theoretical relation has been developed from the Landau free energy expansion between SmC–SmA phase transition temperature of chiral smectic compound and that of its nonchiral analogue. The bilinear and biquadratic coupling constant and the quadrupolar order parameter have been determined from the extended microscopic model in the chiral smectic-C (Sm-C*) phase of four ferroelectric liquid crystal (FLC) materials and results have been discussed.

scholarly journals Fréederisksz Transitions in 6CB Based Ferronematics—Effect of Magnetic Nanoparticles Size and Concentration

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3096
Author(s):  
Katarína Zakutanská ◽  
Danil Petrov ◽  
Peter Kopčanský ◽  
Dorota Węgłowska ◽  
Natália Tomašovičová
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Iron Oxide ◽  
Magnetic Nanoparticles ◽  
Magnetic Fields ◽  
Volume Concentration ◽  
Magnetization Vector ◽  
Oxide Nanoparticles ◽  
Capacitance Measurements ◽  
Electric And Magnetic Fields

In this paper, results acquired from capacitance measurements performed on composites based on nematic liquid crystal 4-cyano-40-hexylbiphenyl (6CB) and spherical iron oxide nanoparticles of various sizes are presented. Electric and magnetic Fréedericksz transitions, as well as structural transitions in combined electric and magnetic fields, were investigated. The obtained results showed the lowering of the threshold magnetic field with an increase in the volume concentration of nanoparticles. Estimations based on results obtained from measurements suggest soft anchoring between liquid crystal director and nanoparticles magnetization vector.

A high-speed and high-efficiency imaging polarimeter based on ferroelectric liquid crystal retarders: Design and test

2021 ◽  
Author(s):  
Jing Guo ◽  
Deqing Ren ◽  
Yongtian Zhu ◽  
Xi Zhang
Keyword(s):  
Liquid Crystal ◽  
Magnetic Fields ◽  
High Speed ◽  
High Efficiency ◽  
Modulation Frequency ◽  
Total Efficiency ◽  
Wide Field ◽  
Ferroelectric Liquid Crystal ◽  
Nonlinear Minimization ◽  
Solar Instruments

Abstract Polarimeters play a key role in investigating solar magnetic fields. In this paper, a High speed and high efficiency Imaging POlarimeter (HIPO) is proposed based on a pair of ferroelectric liquid crystal retarders (FLCs), with the ultimate goal of measuring magnetic fields of prominences and filaments from the ground. A unique feature of the HIPO is that it enables high cadence polarization measurements covering a wide field of view (FOV); the modulation frequency of the HIPO is able to achieve ∼100 Hz, which greatly suppresses the seeing-induced crosstalk, and the maximum FOV can reach 62″ × 525″. Additionally, FLC retardances under low and high states were calibrated individually and found to have a slight discrepancy, which is neglected in most works. Based on FLC calibration results, an optimization was performed using a constrained nonlinear minimization approach to obtain the maximum polarimetric efficiency. Specifically, optimized efficiencies of the Stokes Q, U, and V are well balanced and determined as (ξQ, ξU, ξV) = (0.5957, 0.5534, 0.5777), yielding a total efficiency of 0.9974. Their practical efficiencies are measured as (ξQ′, ξU′, ξV′) = (0.5934, 0.5385, 0.5747), slightly below the optimized values but still resulting in a high total efficiency of 0.9861. The HIPO shows advantages in terms of modulation frequency and polarimetric efficiency compared with most other representative ground-based solar polarimeters. In the observations, measurement accuracy is found to be better than 2.7 × 10−3 by evaluating full Stokes Hα polarimetry results of the chromosphere. This work lays a foundation for the development of high-speed and high-accuracy polarimeters for our next-generation solar instruments.

Theoretical Studies of the Effects of Magnetic Field on the Phase Transition of Swollen Liquid Crystal Elastomers

2015 ◽  
Vol 1123 ◽  
pp. 46-54
Author(s):  
Warsono ◽  
Y. Yusuf ◽  
Pekik Nurwantoro ◽  
Kamsul Abraha
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Liquid Crystal ◽  
Magnetic Fields ◽  
Orientational Order ◽  
Energy Transition ◽  
Isotropic Phase ◽  
Isotropic Mixing ◽  
Transition Points ◽  
Liquid Crystal Elastomers

The effect of magnetic fields on the swelling of liquid crystal elastomers (LCE) dissolved in liquid crystal (LC) solvent have been studied. The Flory-Huggins model used to calculate the free energy of an isotropic mixing and the Maier-Saupe model used to calculate the free energy of a nematic mixing. Numerical integration method used to calculate the orientational order parameter and the total free energy of system (consists of : nematic free energy, elastic free energy, isotropic mixing free energy and magnetic free energy) and the calculation results graphed as a function of temperatures for various magnetic fields and as function of magnetic fields for various of temperatures. We find that the magnetic field shifts the transition points towards higher temperatures, increases the energy transition, and induces an isotropic phase to paranematic phase.

scholarly journals Diamagnetic anisotropy and rotational viscosity of 6CHBT nematic liquid crystal

2021 ◽  
Vol 2056 (1) ◽  
pp. 012029
Author(s):  
A D Kurilov ◽  
I S Chekulaev ◽  
S M Shammai Irani ◽  
N S Parashchuk ◽  
V S Bezruchenko ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Magnetic Fields ◽  
Nematic Liquid Crystal ◽  
Diamagnetic Susceptibility ◽  
Physical Models ◽  
Optical Methods ◽  
Diamagnetic Anisotropy ◽  
Electric And Magnetic Fields ◽  
Rotational Viscosity

Abstract Nematic liquid crystal with polar terminal NCS group was studied by using acoustic and electro-optical methods. Experimental results on rotational viscosity have been obtained by two methods. The anisotropy of diamagnetic susceptibility of the studied LC with temperature variation was determined based on the comparison of these methods. The present results may be useful for testing physical models of the orientation dynamics of nematic liquid crystals in alternating electric and magnetic fields.

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