Flexoelectric polarization studies in bent-core nematic liquid crystals

Sreenilayam, Sithara P.; Panarin, Yu. P.; Vij, J. K.; Torgova, S. I.; Lehmann, Anne; Tschierske, Carsten

doi:10.1103/physreve.92.022502

Cited by 21 publications

(7 citation statements)

References 28 publications

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“…1 . The first compound (BCN66) with a large flexoelectric polarization [ 52 ] is a member of the homologue series consisting of a bent core of five aromatic rings terminated by the two identical alkyl chains with variable chain lengths: C n H 2 n +1 where n varies from 2 to 14. The longer chain components form SmC-like B2 phases [ 53 ].…”

Section: Methodsmentioning

confidence: 99%

Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds

Panarin¹,

Sreenilayam²,

Vij³

et al. 2018

Beilstein J. Nanotechnol.

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Two homologue achiral bent-core liquid crystals (LCs), BCN66 and BCN84, in their nematic phases are studied by dielectric spectroscopy in the frequency range 10 Hz–10 MHz. In each of these compounds, two relaxation processes are identified and assigned to (i) collective dynamics of molecules in nanometer-sized cybotactic clusters and (ii) individual molecular relaxations, in the ascending order of frequency of the probe field. The temperature and the bias electric field dependence of the dielectric strength and relaxation frequency for these processes are shown to give rise to sharpness in cluster boundaries, increased size and volume fraction in the LC nematic phase. The effect of the bias field on the LC cell is similar to reducing its temperature; both variables increase the cluster size and volume fraction and give rise to sharp cluster boundaries. The findings confirm that dielectric spectroscopy is a powerful and an extremely useful technique to provide a deeper understanding of the mechanism of cybotactic cluster formation in the isotropic liquid and the nematic phase of LCs as a function of temperature and the bias field.

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Section: Methodsmentioning

confidence: 99%

Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds

Panarin¹,

Sreenilayam²,

Vij³

et al. 2018

Beilstein J. Nanotechnol.

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“…It should be noted that in the general framework of the Selinger model [16], which has been investigated here from the molecular point if view, the abnormally large values of the flexocoefficients are related to the "pretransitional" increase of the mean-field dielectric susceptibility which is not generally observed in bent-core nematics [40]. On the other hand, molecular theory of the dielectric constant of nematic LCs should be more complicated because dipole-dipole correlations are expected to give a significant contribution.…”

Section: Discussionmentioning

confidence: 99%

Effect of polar intermolecular interactions on the elastic constants of bent-core nematics and the origin of the twist-bend phase

Osipov

Paja̧k

2016

Eur. Phys. J. E

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Abstract. A molecular theory of both elastic constants and the flexoelectric coefficients of bent-core nematic liquid crystals has been developed taking into account dipole-dipole interactions as well as polar interactions determined by the bent molecular shape. It has been shown that if polar interactions are neglected, the elastic constants are increasing monotonically with the decreasing temperature. On the other hand, dipolar interactions between bent-core molecules may result in a dramatic increase of the bend flexocoefficient. As a result, the flexoelectric contribution to the bend elastic constant increases significantly, and the bend elastic constant appears to be very small throughout the nematic range and may vanish at a certain temperature. This temperature may then be identified as a temperature of the elastic instability of the bent-core nematic phase which induces a transition into the modulated phases with bend deformations like recently reported twist-bend phase. The temperature variation of the elastic constants is qualitatively similar to the typical experimental data for bent-core nematics.

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“…The RN-1175 polymer (Nissan Chemicals, Tokyo, Japan) is used to obtain perfect homogeneous alignment. This thermo aligning polymer aligns nematic [30][31][32] and ferroelectric [33][34][35][36] LC molecules homogenously in cells. The spin coated (3000 rpm, 30 s) Indium Tin Oxide (ITO) glass substrates were baked at 250 °C for an hour to generate planar alignment by evaporating excess solvent.…”

Section: Methodsmentioning

confidence: 99%

Fast Ferroelectric Liquid Crystal Based Optical Switch: Simulation and Experiments

Sreenilayam

Brabazon

Panarin³

2019

Crystals

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The present work explains simulation and experimental investigation of the most significant performance parameters of a ferroelectric liquid crystal (FLC) optical switch. The measurements were carried out with commercially available FLC mixture (θ = 22.5 • ), having a very fast response time within the range of 1-10 µs. The best achieved cross talk was~19 dB, which is an exact match with the theoretical result.

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Flexoelectric polarization studies in bent-core nematic liquid crystals

Cited by 21 publications

References 28 publications

Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds

Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds

Effect of polar intermolecular interactions on the elastic constants of bent-core nematics and the origin of the twist-bend phase

Fast Ferroelectric Liquid Crystal Based Optical Switch: Simulation and Experiments

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