6 edition of X-Ray Diffraction Study of Nematic, Smectic A and C Liquid Crystals found in the catalog.
January 31, 1989
Written in English
|Series||Soviet Scientific Reviews Series, Section a|
|The Physical Object|
|Number of Pages||68|
X-Ray Diffraction from a Smectic a Liquid Crystal Electron Diffraction Study of Liquid Crystals Neutron Critical Scattering in PPA On The Structure and Dynamics of D-PAA Neutron Scattering The Re-Entrant Phenomenon in 4'-n-OctyloxyCyanobiphenyl: A High Pressure X-Ray Study of the Smectic a Layer Spacing Some Physical Properties of Re-Entrant. A new liquid crystal compound 3,5-bis-(phexenyloxyphenyl)-isoxazole has been characterized using X-ray diffraction. From the detailed study of the inner and outer reflection, along the meridional and equatorial directions, respectively, the orientational and translational order parameters have been determined in the nematic and smectic A phases.
Liquid crystals (LCs) are a state of matter which has properties between those of conventional liquids and those of solid instance, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of liquid-crystal phases, which can be distinguished by their different optical properties (such as textures). Ordinary nematic liquid crystals were left out in order to limit the size of the meeting. The number of registered participants still reached The conference shed new light on the classification of smectic mesophases, especially through the interaction of the Halle (GDR) and Hull (England) groups.
The X-ray diffraction pattern retains sharp small-angle signals, and the high angle signal is split and narrowed, suggesting a tilted hexatic-type smectic phase. This shows that the SmX phases present in the CB6OBA: n OS series (n = 3–10) and CB6OBA:(S)-(2-Me)4OS are the same, and we have denoted the latter SmX* as it is formed from chiral. Picture of the smectic C phase Photo of the smectic C phase (using polarizing microscope) As in the nematic, the smectic−C mesophase has a chiral state designated C*. Consistent with the smectic−C, the director makes a tilt angle with respect to the smectic layer. The difference is that this angle rotates from layer to layer forming a helix.
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X-ray diffraction study of ‘side-on fixed’ homopolysiloxanes from nematic to smectic C phases. Liquid Crystals: Vol. 19, No. 5, pp. Cited by: Structural Studies of Liquid Crystals by X‐Ray Diffraction.
John M. Seddon. Search for more papers by this author. Liquid Crystals, Merck House, Poole BH15 1TD, U.K. Nematic Phase. Smectic A and Smectic C Phases.
Modulated and Incommensurate Fluid Smectic Cited by: Jan P. Lagerwall, Frank Giesselmann, Christine Selbmann, Sebastian Rauch and Gerd Heppke, Generation of frustrated liquid crystal phases by mixing an achiral nematic–smectic-C mesogen with an antiferroelectric chiral smectic liquid crystal, The Journal of Chemical Physics,14, (), ().Cited by: Reentrant nematic phases and smectic antiphases occur as intermediate states between two one-dimensionally ordered frustrated smectic phases, characterized by two competing and, in general, incommensurate smectic density waves.
Using high-resolution x-ray diffraction, we have examined the evolution of the two density waves as a function of temperature in all phases of a mixture of polar liquid Cited by: 8. The effects of dispersed aerosil nanoparticles on two of the phase transitions of the thermotropic liquid-crystal material 4-n-pentylphenylthiol-4'-n-octyloxybenzoate (8̄S5) have been studied using high-resolution x-ray diffraction techniques.
The aerosils hydrogen bond together to form a gel which imposes a weak quenched disorder on the liquid crystal. The smectic Cited by: 5. Liquid crystal polymers (LCP) were compared with monomeric liquid crystals (MLC) by means of high-resolution x-ray (HIREX) and light scattering (LIS).
Both HIREX and LIS were used to study the nematic-smectic(sub a) phase transition of P polysiloxane; the following critical exponents were determined: nu(sub parallel) = +/; nu(sub normal) = +/.
A short review is given of recent X-ray diffraction studies of the phases and phase transitions of thermotropic liquid crystals. The areas covered are twist-grain-boundary phases, antiferroelectric phases studied with resonant X-ray diffraction and smectic phases within gel structures.
In all areas, X-ray diffraction has played a key role. X-Ray Diffraction From Free Standing Films of Hexatic Smectic Liquid Crystals. Molecular Crystals and Liquid Crystals: Vol. No. 1, pp. 1 January Small-angle x-ray diffraction study of mixtures showing re-entrant nematic phase and induced smectic A d phase S.
Giri, N. Pradham, R. Paul, S. Paul, P. Mandal, Roman S. Dabrowski, M. Brodzik, Krzysztof L. Czuprynski. Garland's research works with 5, citations and 2, reads, including: Smectic-A and Smectic-C Phases and Phase Transitions in Liquid Crystal-Aerosil Gels.
Bent-core liquid crystals showing a nematic phase stable at low temperatures are very attractive for applicative purposes in view of the inherent biaxial nature of the nematic phase.
In this work, a typical five-ring bent-core mesogen was investigated by means of 2H NMR spectroscopy and X-ray diffraction (XRD) methods. These techniques provide complementary information on the. Small angle X-ray diffraction from the uniaxial nematic phase of certain bent-core liquid crystals is shown to be consistent with the presence of molecular clusters possessing short-range tilted smectic (smectic-C) order.
Persistence of these clusters throughout the nematic phase, and even into the isotropic state, likely accounts for the unusual macroscopic behavior.
We have studied the x-ray diffraction pattern associated with very well ordered smectic A liquid crystals. The smectic A order parameter, Φ = Φ 0 e iΦ, has two components: the phase Φ which describes the one dimensional translational symmetry and the amplitude, Φ 0, which gives a measure of the strength of the layer ordering.X-ray's scattered by a smectic A liquid.
“Resonant x-ray Scattering: a tool for structure elucidation in liquid crystals” n and L.S. Hirst, CHEM PHYS CHEM, 7, () “Interlayer structures of the chiral smectic liquid crystal phases revealed by x-ray resonant scattering”.
Smectic layering in polyphilic liquid crystals: X-ray diffraction and infra-red dichroism study Article (PDF Available) in Journal of Physics B Atomic and Molecular Physics 3(7). X-Ray Diffraction Intensities of a Smectic-A Liquid Crystal Article (PDF Available) in Physical Review Letters 44(23) June with Reads How we measure 'reads'.
High-resolution x-ray study of nematic-smectic-A and smectic-A-reentrant-nematic transitions in liquid-crystal-aerosil gels. Ramazanoglu M, Larochelle S, Garland CW, Birgeneau RJ. Phys Rev E Stat Nonlin Soft Matter Phys, 77(3 pt 1), 14 Mar Cited by: 0 articles | PMID: Raman Imaging of Nematic and Smectic Liquid Crystals.
x-ray diffraction , and Fourier transform infrar ed The next st ep in th is study was to use this mode l system to sh ow the. Liquid crystal displays (LCD’s) are found in calculators, wrist watches, TV screens and a host of other objects in use.
Three types of molecular arrangements, known as nematic, smectic and cholesteric liquid crystals have been identified. Several unsymmetrical molecules that have approximately rod-like shapes behave as liquid crystals. An analysis is given of the various contributions to the x-ray diffraction in smectic-A liquid crystals, where several effects due to the real structure are superimposed upon the.
X-ray diffraction patterns were recorded photographically on a flat plate camera using CuK α radiation of wavelength Å at 5°C below the nematic-smectic transition temperature for five mixtures exhibiting induced smectic phase with unaligned samples.
Temperatures were measured and regulated with a precision temperature controller.We have studied the x-ray diffraction pattern associated with very well ordered smectic A liquid crystals.
The smectic A order parameter, Φ = Φ 0 e iΦ, has two components: the phase Φ which describes the one dimensional translational symmetry and the amplitude, Φ 0, which gives a measure of the strength of the layer ordering. The isotropic X-ray diffraction pattern of DTA + 4BA shown in Fig. 9b, indicates a decaying peak at °.
In addition to this, the absence of any other peak indicates the annihilation of smectic X* ordering. In the thermal range of smectic X* at two other temperatures namely 97 °C, °C, X-ray diffraction studies have been carried out.