A liquid crystal dielectric applicable to high-frequency electromagnetic wave modulation has a clearing point of the liquid crystal dielectric higher than 110° C., a low-temperature storage temperature lower than −20° C., and an optical anisotropy greater than 0.35. The liquid crystal dielectric includes: one or more compounds selected by general formula I, which occupy 30-80% of the total weight of the liquid crystal dielectric, and one or more compounds selected by general formula II and/or general formula III, which occupy 20-70% of the total weight of the liquid crystal dielectric. The liquid crystal dielectric has good low-temperature stability, high dielectric anisotropy, a high phase width, appropriate rotary viscosity, appropriate optical anisotropy, low dielectric loss, and a low loss tangent, exhibits strong high-frequency electromagnetic wave tuning capability, is specifically suitable for electromagnetic wave modulation in microwave or millimeter wave areas, and has a good application prospect in liquid crystal phase shifters.

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Liquid crystal-based devices for detecting a target contaminant in air, including hydrogen, nitrogen dioxide, ozone, ammonia or carbon monoxide, and methods of using such devices to detect the target contaminant are disclosed. Such devices have a substrate surface that includes one or more metals or metal alloys that is in contact with a liquid crystal composition. When the device is contacted with a sample that contains the target contaminant, an observed change in the orientational ordering of the liquid crystal signals the presence of the target contaminant. In the absence of the target contaminant, no change in orientational ordering occurs.

The Kerr effect depends very strongly on the temperature and is associated with high operating voltages. The present invention relates to an electrically controllable optical element which comprises a cell (D) filled with a starting mixture (K) and having two substrates (1a, 1b) and a conductive layer (2a, 2b) applied onto the inner surface of the respective substrate (1a, 1b), wherein the starting mixture (K) comprises a mixture of dipolar, rod-shaped molecules (5) and semi-mesogenes (4) as active constituents, and wherein the starting mixture (K) forms a thin layer having a wide-meshed, anisotropic network (9) produced by photo-polymerization between the structured or/and flat conductive layers (2a, 2b), which are applied onto a substrate (1a, 1b), in a thin-film cell (D). According to the invention, an optically active surface profile (O) is incorporated on the inner surface of a substrate (1a or 1b) or into the substrate (1a or 1b) or both substrates (1a and 1b).

In order to configure or produce an electrically controllable optical element on the basis of the electro-optic Kerr effect with a low threshold and operating voltage, a minimized temperature dependence of the effect and a low response time, the Kerr liquid according to the invention comprises a mixture of rod-shaped molecules and non-rod-shaped molecules as active composites, a thin layer having a pre-stamping, wide-mesh, anisotropic network between structured and/or planar conductive layer applied to a substrate thus configure a thin-film cell in such a way that without electric field the state of the active composite of the Kerr liquid in the working temperature region RT is isotropic and that by electrically continuous adjustment, of the voltage U or by a switching-on or switching-off a change the voltage U, in the optical element a voltage-induced phase shift or a refractive index deviation is generated and the light passes through an electrode gap perpendicular to the electrodes.

A smectic A composition with the positive dielectric anisotropy exhibiting a monolayer smectic A structure (SmA.sub.1), which shows a phase transition from a smectic A phase to an isotropic phase (SmA-Iso) or a phase transition from a smectic A phase through a nematic phase to an isotropic phase (SmA-N-Iso) and includes at least two fluorinated compounds selected from the families of fluorinated derivatives of biphenyls and terphenyls expressed by the general formulae 1-12.

For ensuring of the high level of the conductivity the composition is doped with the ionic amidynium salts and/or the ionic potassium complexes of the crown ethers wherein the charge on the cation is delocalized. Such a structure of the ionic compound ensures the better solubility in the liquid crystalline fluorinated composition in comparison to that observed for quaternary ammonium salts.

For writing of the information the dynamic scattering effect (DS) was used, where the transition from a opaque (milky) state to a clear (transparent) state or reversal process is obtained by the change of the frequency of a driving alternating electric field.

The modification of the properties of the smectic A composition by adding of further components such as fluorinated four ring liquid crystal compounds or pyrimidine compounds or cyanocompounds is described.

The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having positive dielectric anisotropy, characterised in that it comprises one or more compounds of the formula I in a total concentration of ≥40%, ##STR00001##
in which the parameters have the meanings indicated in claim 1, and to the use of the liquid-crystalline medium for electro-optical purposes, in particular in liquid-crystal light valves for lighting devices for motor vehicles, and to liquid-crystal light valves which comprise this medium and lighting devices for motor vehicles which contain such liquid-crystal light valves.

A composition having a high n, a wide temperature range of a liquid crystal phase, low viscosity, good solubility at a low temperature, high resistivity, a high voltage holding ratio, and stability against heat and light; a liquid crystal composition containing the composition, the liquid crystal composition having a good lens effect and good chemical stability; a liquid crystal display device including the liquid crystal composition; and a liquid crystal lens including the liquid crystal composition. The liquid crystal composition contains one or two or more compounds represented by general formula (i) and one or two or more compounds represented by general formula (ii).

An object of the present invention is to provide a composition that realizes high n, has a wide liquid crystal phase temperature range, small viscosity, excellent low-temperature solubility, and high resistivity and voltage holding ratio, and is stable against heat and light, and to provide a liquid crystal composition having an excellent lens effect and excellent chemical stability using the composition, and a liquid crystal display device and a liquid crystal lens that use the liquid crystal composition. The present invention provides a liquid crystal composition that contains one or two or more compounds represented by general formula (i) and one or two or more compounds represented by general formula (ii), a liquid crystal display device using the liquid crystal composition, a liquid crystal lens using the liquid crystal composition, and a birefringence lens for stereoscopic image display using the liquid crystal composition.

A nanoparticle film is disclosed. The nanoparticle film comprises a plurality of polymerized liquid crystal monomers having an axis of alignment, and a plurality of nanoparticles disposed in the polymerized liquid crystal monomers. Each of the nanoparticles has a surface modified by a plurality of first ligands and a long axis aligned with the axis of alignment through the plurality of first ligands.

The new LC media exhibit a ferroelectric nematic phase at ambient temperature. They comprise at least one or more compounds selected from each of formula IA, of formula IB and of the group of formulae IC-1/IC-2/IC-3,

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in which the variable groups have the meanings indicated in the text and in the claims. The mixtures are useful for electro-optics, electronics, electro-mechanic and other applications for materials with very high dielectric permittivity and other energy-saving applications.