Flexoelectricity is a coupling between orientational deformation and electric polarization. We present direct method for measuring the flexoelectric coefficients of nematic liquid crystals (NLCs) via current produced by periodic mechanical flexing NLC's bounding surfaces. This suitable response bent-core crystals, which are expected to demonstrate much larger effect than traditional, calamitic crystals. Our results reveal that not only bend coefficient NLCs gigantic (more 3 orders magnitude...

In this work the 4-(trans- 4'-n -hexylcyclohexyl)-isothiocyanatobenzene (6CHBT) liquid crystal was doped with differently shaped magnetite nanoparticles. The structural changes were observed by capacitance measurements and showed significant influence of shape size magnetic particles on Fréedericksz transition. For volume concentration phi= 2 x 10(-4) particles, critical field established for pure crystal, crystals spherical, chainlike, rodlike particles. depends type anchoring, which is...

Electric field-induced patterns in liquid crystals have been observed and studied for about 50 years. During this time, a great variety of structures, detected under different conditions, described; theoretical descriptions were also developed parallel with the experiments huge number papers published. The non-vanishing interest topic is due to several factors. First, most experimentalists working new (or even well-known) apply sooner or later an electric field purposes and, as response,...

Dielectric spectroscopy measurements have been performed on a bent-core nematic liquid crystal and its binary mixtures with calamitic nematic. We detected more dispersions in the compound than one, including one at an unusually low frequency of few kilohertz. The identified spectra split into contributions constituents. In order to connect dielectric increment molecular dipole moment we applied sophisticated conformational calculation not before for large, flexible mesogen molecule numerous...

The response in capacitance to low external magnetic fields (up 0.1 T) of suspensions spherical nanoparticles, single-wall carbon nanotubes (SWCNT), SWCNT functionalized with carboxyl group (SWCNT-COOH), and Fe(3)O(4) nanoparticles a nematic liquid crystal has been studied experimentally. volume concentration was φ(1)=10(-4) φ(2)=10(-3). Independent the type linear (far below Fréederiksz transition threshold) observed, which is not present undoped nematic.

2014 Un nouvel effet électromécanique a été trouvé dans des cristaux liquides S*C orientés planairement, sous l'influence d'un champ électrique alternatif appliqué.En plus du phénomène électrooptique bien connu, vibrations mécaniques ont observées la direction parallèle aux couches smectiques et perpendiculaire au électrique.Abstract.2014 A new electromechanical effect has been found in planar oriented liquid crystals under the influence of an applied alternating electric field.Apart from...

Abstract The effect of the thermomechanical coupling on homeotropic texture a compensated cholesteric in investigated. coefficient is estimated for deformation.

Liquid-crystal display technology is ubiquitous, but these materials can also be used to make electrically tunable components for optics and photonics. The authors demonstrate voltage control of the wavelength flexoelectric domains in a transmissive diffraction grating, which enables dynamic light steering. They prove that mechanism pattern onset differs from switching between flexodomain states, they explain surprising finding response increasing much slower than decreasing voltage.

The onset of electroconvection in binary mixtures a bent-core and rodlike nematic has been characterized by measuring the threshold voltage ${U}_{c}$ critical wave number pattern wide range frequencies $f$. In rich molecules, ``conductive-prewavy2-patternless-prewavy1'' morphological sequence detected with an unusual negative slope ${U}_{c}(f)$ at high frequencies. This latter scenario seems to be related component, as it disappears increasing concentration molecules. addition, one...

Stable colloidal suspensions of single-walled carbon nanotubes (SWCNT) and magnetite-labeled SWCNT (SWCNT/Fe3O4) in thermotropic liquid crystal 4-(trans-4′-n-hexylcyclohexyl)isothiocyanatobenzene (6CHBT) were investigated. The presence the magnetite SWCNT/Fe3O4 product has been checked with infrared spectroscopy. Transmission electron microscopy employed to obtain structural dimensional data for used samples. Magnetic properties samples have investigated by a SQUID magnetometer significant...

ABSTRACT The purpose of this study is to identify the relationship between electrical and structural characteristics multiwalled carbon nanotubes dispersed into polymer matrix a resin. In first step, composites were characterized by small‐angle neutron scattering, which provide information about bulk dispersion in form three‐dimensional networks with surface fractal behavior. second dielectric was carried out frequency range 1 Hz 10 MHz at room temperature. We have found that electric...

The electrical properties of epoxy polymer/carbon nanotubes composites were characterized using impedance spectroscopy in the frequency range between 1 Hz and 10 MHz temperature 25°C 105°C. We report analysis experimental data electric modulus formalisms to understand dielectric relaxation mechanisms. variation real imaginary parts versus suggestive two processes, associated with dipolar CNT-polymer interfaces. Havriliak-Negami model was used for modelling extracting parameters.

The influence of the shape anisotropy magnetic particles on isotropic-nematic phase transition was studied in ferronematics based nematic liquid crystal 4-(trans-4-n-hexylcyclohexyl)-isothiocyanato-benzene (6CHBT). doped with spherical or rod-like different size and volume concentrations. from isotropic to observed by polarizing microscope as well capacitance measurements. concentration is demonstrated. results are a good agreement recent theoretical predictions.

Abstract A new photoresponsive bent‐core nematic (BCN) material, which exhibits flexoelectric domains (FDs) driven by electric field, is reported. Unexpectedly, it found that the morphologies of FDs can be controlled irradiation with light fields. This tunability ascribed to photoisomerization effect azo moiety within BCN molecules, where ratio trans and cis isomers changes according parameters resulting in adjustable threshold periodicity FDs. Based on this principle, a prototype...

Detailed analysis is given of the electromechanical effect in planar S*c liquid crystals. Experimental data are presented for amplitude vibration as a function frequency, applied voltage and temperature. The existence frequency dependence linear explained within framework continuum theory.

Electric-field-driven pattern formation has been investigated in a nematic liquid crystal with negative dielectric and conductivity anisotropies. Despite the fact that standard Carr-Helfrich theory predicts no hydrodynamic instability for such compound, experiments reveal convection patterns which we call nonstandard electroconvection (ns-EC). In this work, characterize ns-EC by measuring frequency, thickness, temperature dependence of threshold voltage, wave number, roll orientation, etc.,...

In this work we describe the observations of structural transitions in ferronematics based on thermotropic nematics 6CHBT (4-trans-4'-n-hexyl-cyclohexyl-isothiocyanato-benzene). The ferronematic droplets were observed solutions nematogenic dissolved phenyl isocyanate and doped with fine magnetic particles. phase diagram from isotropic to nematic via a droplet state was found. Magneto-dielectric measurements various new system enabled us estimate type anchoring molecules particle surfaces droplets.

The influence of the inclusion dodecanethiol functionalized gold particles (with diameter 3-5 nm) on structural transitions was investigated.The studied samples were based nematic liquid crystal 4-(trans-4 -n-hexylcyclohexyl)-isothiocyanatobenzene (6CHBT).The volume concentration φ 1 = 2 × 10 -4 and -3 .The obtained results showed that in 6CHBT increases sensitivity such system external magnetic field.

The effect of director pretilt on the twist magnetic Fr\'eedericksz transition nematics was investigated in a planar cell. configuration calculated as function inductance. dielectric and optical response nematic liquid crystal numerically modeled. A measurement method for determining elastic constant ${K}_{22}$ is presented. influence conditions Mauguin discussed. theoretical predictions were confirmed by our experiments. Experimental data all constants bent-core material are presented

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