A material used in an element for phase control of an electromagnetic wave signal having a frequency of 1 GHz to 10 THz. A liquid crystal composition containing at least one compound selected from a group of compounds represented by Formula (1), at least one compound selected from a group of compounds represented by Formula (2) and at least one compound selected from a group of compounds represented by Formula (3).

##STR00001##

For example, R.sup.1, R.sup.21, R.sup.22, R.sup.31, and R.sup.32 are alkyls having 1 to 12 carbon atoms; a ring A.sup.1 is 1,4-phenylene; Z.sup.11, Z.sup.13, Z.sup.21, Z.sup.23, Z.sup.31, and Z.sup.33 are single bonds; Z.sup.12, Z.sup.22, and Z.sup.32 are —C≡C— or —C≡C—C≡C—; L.sup.13 to L.sup.16, L.sup.21 to L.sup.23, and L.sup.31 to L.sup.36 are hydrogen or fluorine; Y.sup.11 and Y.sup.12 are hydrogen or fluorine; and n.sup.1 is 0.

A material used in an element for phase control of an electromagnetic wave signal having a frequency of 1 GHz to 10 THz. A liquid crystal composition containing at least one compound selected from a group of compounds represented by Formula (1), at least one compound selected from a group of compounds represented by Formula (2) and at least one compound selected from a group of compounds represented by Formula (3).

##STR00001##

For example, R.sup.1, R.sup.21, R.sup.22, R.sup.31, and R.sup.32 are alkyls having 1 to 12 carbon atoms; a ring A.sup.1 is 1,4-phenylene; Z.sup.11, Z.sup.13, Z.sup.21, Z.sup.23, Z.sup.31, and Z.sup.33 are single bonds; Z.sup.12, Z.sup.22, and Z.sup.32 are —C≡C— or —C≡C—C≡C—; L.sup.13 to L.sup.16, L.sup.21 to L.sup.23, and L.sup.31 to L.sup.36 are hydrogen or fluorine; Y.sup.11 and Y.sup.12 are hydrogen or fluorine; and n.sup.1 is 0.

The present invention relates to liquid-crystalline media comprising one or more mesogenic compounds of formula I as set forth hereinafter, wherein the one or more compounds of formula I are contained in the medium in an amount, based on the overall contents of the medium, of at least 15% by weight. The present invention further relates to a switching layer, a switching element and a window element containing the liquid-crystalline medium.

Described herein are liquid crystal compositions that can allow for the adjustment of their refractive indices by the application of an electric field. Also described herein are liquid crystal mixtures containing these compositions. In addition, selectively dimmable reverse-mode polymer dispersed liquid crystal (PDLC) elements and devices using these compositions are also described, which are transparent when no or low voltage is applied and opaque when a voltage or high voltage is applied.

Described herein are liquid crystal compositions that can allow for the adjustment of their refractive indices by the application of an electric field. Also described herein are liquid crystal mixtures containing these compositions. In addition, selectively dimmable reverse-mode polymer dispersed liquid crystal (PDLC) elements and devices using these compositions are also described, which are transparent when no or low voltage is applied and opaque when a voltage or high voltage is applied.

A liquid crystal composition and a liquid crystal display device including the liquid crystal composition include at least one compound of general formula I and at least one compound of general formula II. Compared with the prior art, the liquid crystal composition has a smaller voltage change rate at high and low temperatures and a shorter low temperature response time, while maintaining an appropriate optical anisotropy, an appropriate clearing point, an appropriate absolute value of dielectric anisotropy, such that the liquid crystal display device having the liquid crystal composition has a better display and a faster response speed.

##STR00001##

A liquid crystal composition and a liquid crystal display device including the liquid crystal composition include at least one compound of general formula I and at least one compound of general formula II. Compared with the prior art, the liquid crystal composition has a smaller voltage change rate at high and low temperatures and a shorter low temperature response time, while maintaining an appropriate optical anisotropy, an appropriate clearing point, an appropriate absolute value of dielectric anisotropy, such that the liquid crystal display device having the liquid crystal composition has a better display and a faster response speed.

##STR00001##

There are provided a liquid crystal composition containing one or two or more compounds represented by general formula (L) and three or four or more dichroic dyes selected from azo compounds, and a guest-host liquid crystal display device or light-controlling device that uses the liquid crystal composition. The liquid crystal composition according to the present invention contains dichroic dyes that satisfy high contrast, high solubility, high nematic-isotropic transition temperature (T.sub.NI), and low birefringent anisotropy (Δn) effective for high light resistance and high thermal resistance at the same time. The use of the liquid crystal composition according to the present invention provides a liquid crystal display device or a light-controlling device that exhibits a good-looking black color and has high contrast, high display quality, and high practicality.

The present invention relates to polymerisable compounds, to processes and intermediates for the preparation thereof, to liquid-crystal (LC) media comprising them, and to the use of the polymerisable compounds and LC media for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the polymer sustained alignment type.

The present invention relates to polymerisable compounds, to processes and intermediates for the preparation thereof, to liquid-crystal (LC) media comprising them, and to the use of the polymerisable compounds and LC media for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the polymer sustained alignment type.