摘要:

Within the framework of continuum theory of nematic ordering a new class of defects, which have stable director fields of cylindrical type with integer and half-integer topological invariants, has been studied.

ISSN:1058-725X    

DOI:10.1080/10587259508041722

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Low molar mass liquid crystals with phase properties similar to polymers may be obtained by the addition of a disiloxane tail to an organic mesogen. We present a comparison of the properties of two chiral mesogens (based on the 4-((S)-(+) 2-Methylbutanoyloxy)phenyl 4-(9-decenyloxy)benzoate and 4-((2S)-2-Chloro-3- methylbutanoyl)phenyl 4′-(9-decenyloxy)benzoate moieties) with and without a pentamethyl disiloxane tail and with their vinyl-terminated analogues. We show a general decrease in transition temperatures, and a widening of the mesophase range in the disiloxane-substituted materials due to a suppression of the crystallisation temperature. The phases exhibited are modified, with a tilted smectic-C phase favoured on substitution of the disiloxane tail, eliminating the smectic-A phase found in the unsubstituted mesogen; this gives high tilt angle (28–36°) single mesophase materials. We summarise the electro-optic properties of a series of the disiloxane-substituted materials, which show low viscosity (∼500mPas) and moderate spontaneous polarisation (20–150nCcm−2) across the range of materials, and show their variation with temperature. We demonstrate the variations of these properties with varying alkyl spacer length, alkyl tail length and changing chiral end-group.

ISSN:1058-725X    

DOI:10.1080/10587259508041723

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The dielectric properties of a ferroelectric liquid crystal mixture of low spontaneous polarizatian have been studied here as a function of D. C. bias voltage, frequency and cell thickness. A small sharp peak of dielectric constant is found to become prominent at the chiral smetic C-smectic A phase transition under the condition in which Goldstone mode is suppressed. The relaxation frequency, dielectric strength and the rotational viscosity of the Goldstone mode have been determined under D.C. bias field.

ISSN:1058-725X    

DOI:10.1080/10587259508041724

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Single- and multichannel optoelectronic modulators with twist- and supertwist transmissive or reflective LC cells are described. The possibility of antidazzling aplications of these devices at low background intensity (0, 1–10 1x) is discussed.

ISSN:1058-725X    

DOI:10.1080/10587259508041725

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Spatial light modulators (SLM) are miniature high-resolution devices of optical processors and displays. The influence of various Physical parameters of a LC material on the SLM optical response, speed of response and other informatlon characteristics is considered. The Possibility of the optical memory in SLM and non-linear optical control is also discussed.

ISSN:1058-725X    

DOI:10.1080/10587259508041726

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An ellectrically controlable optical light attenuator operating on the light scattering effect in a liquid crystalline cell was arranged for optoelectronic applications and examined. Its optical properties and performance are presented and discussed.

ISSN:1058-725X    

DOI:10.1080/10587259508041727

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Amorphous twisted nematic liquid crystal display(a-TN) cells have been prepared without rubbing. The liquid crystal is injected into the cell in the isotropic phase and then cooled down to the nematic phase. The cooling rate and the uniformity are critical for the preparation of the a-TNs. Nematic liquid crystals, both with and without chiral dopant, have been used for the a-TNs. The electro-optical characteristics of the a-TN have been measured. Theoretical calculations have been carried out by 4 × 4 matrix method. A rising time of 700 μs and a decreasing time of 48ms have been detected. It is shown that the a-TN devices exhibit wide and uniform viewing angle characteristics. A viewing angle of ± 30 degrees has been achieved.

ISSN:1058-725X    

DOI:10.1080/10587259508041728

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The effectiveness of matrix-type spatial-temporal LC modulators used in information-array formation circuits depends not only on the electrooptic parameters of the modulating layer but also on the modulator design.

ISSN:1058-725X    

DOI:10.1080/10587259508041729

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Morphological peculiarities of supermolecular structure of native and model lyomesogenes on aggregation are discussed.

ISSN:1058-725X    

DOI:10.1080/10587259508041730

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The study of structural reconstructions in liquid crystalline phases of mesomorphic lecithin-water system due to the hydrogen-deuterium isotopic replacement was made by the positron annihilation and infrared spectroscopy methods. The changes in values of parameters of molecular interactions stipulated by such isotopic effect were obtained from the analysis of experimental and theoretical data.

ISSN:1058-725X    

DOI:10.1080/10587259508041731

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor