Pattern Formation and Phase Transitions in Bent-core Liquid Crystals PDF Download

Author: David Wiant
Publisher:
ISBN:
Category :
Languages : en
Pages : 223

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Author: Agnes Buka
Publisher: Springer Science & Business Media
ISBN: 146123994X
Category : Science
Languages : en
Pages : 344

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Book Description
In the last 20 years the study of nonlinear nonequilibrium phenomena in spa tially extended systems, with particular emphasis on pattern-forming phenomena, has been one of the very active areas in physics, exhibiting interesting ramifi cations into other sciences. During this time the study of the "classic" systems, like Rayleigh-Benard convection and Taylor vortex flow in simple fluids, has also been supplemented by the study of more complex systems. Here liquid crystals have played, and are still playing, a major role. One might say that liquid crystals provide just the right amount and right kind of complexity. They are full of non linearities and give rise to new symmetry classes, which are sometimes actually simpler to deal with qualitatively, but they still allow a quantitative description of experiments in many cases. In fact one of the attractions of the field is the close contact between experimentalists and theorists. Hydrodynamic instabilities in liquid crystals had already experienced a period of intense study in the late 1960s and early 1970s, but at that time neither the ex perimental and theoretical tools nor the concepts had been developed sufficiently far to address the questions that have since been found to be of particular interest. The renewed interest is also evidenced by the fact that a new series of workshops has evolved. The first one took place in 1989 in Bayreuth and united participants from almost all groups working in pattern formation in liquid crystals.

Author: Hideo Takezoe
Publisher: CRC Press
ISBN: 1315355418
Category : Science
Languages : en
Pages : 290

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Book Description
Bent-Shaped Liquid Crystals: Structures and Physical Properties provides insight into the latest developments in the research on liquid crystals formed by bent-shaped mesogens. After a historical introduction, the expert authors discuss different kinds of mesophase structures formed by bent-shaped molecules. This book devotes the majority of its pages to physical properties such as polar switching, optics and non-linear optics, and behavior in restricted geometries. However, as chemistry is often highly relevant to the emergence of new phases, particularly with reflection symmetry breaking, it also involves a broad spectrum of interesting chemistry viewpoints.

Author: Arthur N. Chester
Publisher: Springer Science & Business Media
ISBN: 1468491512
Category : Science
Languages : en
Pages : 492

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Book Description
The Nato Advanced Study Institute "Phase Transitions in Liquid Crystals" was held May 2-12, 1991, in Erice, Sicily. This was the 16th conference organized by the International School of Quantum Electronics, under the auspices of the "Ettore Majorana" Centre for Scientific Culture. The subject of "Liquid Crystals" has made amazing progress since the last ISQE Course on this subject in 1985. The present Proceedings give a tutorial introduction to today's most important areas, as well as a review of current results by leading researchers. We have brought together some of the world's acknowledged experts in the field to summarize both the present state of their research and its background. Most of the lecturers attended all the lectures and devoted their spare hours to stimulating discussions. We would like to thank them all for their admirable contributions. The Institute also took advantage of a very active audience; most of the students were active researchers in the field and contributed with discussions and seminars. Some of these student seminars are also included in these Proceedings. We did not modify the original manuscripts in editing this book, but we did group them according to the following topics: 1) "Theoretical Foundations"; 2) "Thermotropic Liquid Crystals"; 3) "Ferroelectric Liquid Crystals"; 4) "Polymeric Liquid Crystals"; and 5) "Lyotropic Liquid Crystals".

Author: Shri Singh
Publisher: Springer Nature
ISBN: 303150058X
Category :
Languages : en
Pages : 578

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Author: Peter S Pershan
Publisher: World Scientific
ISBN: 9814507504
Category : Science
Languages : en
Pages : 443

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Book Description
Current understanding of different phases as well as the phase transitions between them has only been achieved following recent theoretical advances on the effects of dimensionality in statistical physics. P S Pershan explains the connection between these two separate areas and gives some examples of problems where the understanding is still not complete. The most important example is the second order phase transition between the nematic and smectic-A phase. Others include the relation between the several hexatic phases that have been observed and the first order restacking transitions between phases that were all previously identified as smectic-B, but which should more properly be identified as crystalline-B. Some relatively recent experimental developments on the discotic phase, liquid crystal surfaces and lyotropic phases are also included. The book includes 41 major reprints of some of the recent seminal work on the structure of liquid crystals. They are introduced by a brief review of the symmetries and other properties of liquid crystalline phases. In addition, there is a discussion of the differences between true liquid crystalline phases and others that were described as liquid crystalline in the early literature, but which have since been shown to be true three-dimensional crystals. The progression from the isotropic fluid, through the nematic, smectic, and various crystalline phases can be understood in terms of a systematic decrease in symmetry, together with an accompanying variation in structure is explained. A guide to the selected reprints and a sort of “Rosetta Stone” for these various phases is provided. The goal of this book is to explain the systematics of this progression to students and others that are new to this field, as well as to provide a useful handbook for people already working in the field.

Author: Roland Ennis
Publisher:
ISBN:
Category : Hydrodynamics
Languages : en
Pages : 620

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Author: Yurii Aleksandrovich Izyumov
Publisher: Springer Science & Business Media
ISBN: 9400919204
Category : Science
Languages : en
Pages : 462

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Book Description
About half a century ago Landau formulated the central principles of the phe nomenological second-order phase transition theory which is based on the idea of spontaneous symmetry breaking at phase transition. By means of this ap proach it has been possible to treat phase transitions of different nature in altogether distinct systems from a unified viewpoint, to embrace the aforemen tioned transitions by a unified body of mathematics and to show that, in a certain sense, physical systems in the vicinity of second-order phase transitions exhibit universal behavior. For several decades the Landau method has been extensively used to an alyze specific phase transitions in systems and has been providing a basis for interpreting experimental data on the behavior of physical characteristics near the phase transition, including the behavior of these characteristics in systems subject to various external effects such as pressure, electric and magnetic fields, deformation, etc. The symmetry aspects of Landau's theory are perhaps most effective in analyzing phase transitions in crystals because the relevant body of mathemat ics for this symmetry, namely, the crystal space group representation, has been worked out in great detail. Since particular phase transitions in crystals often call for a subtle symmetry analysis, the Landau method has been continually refined and developed over the past ten or fifteen years.

Author: Strahinja Stojadinovic
Publisher:
ISBN:
Category : Light
Languages : en
Pages : 219

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Book Description
Dynamical properties of the nematic and isotropic phase of several relatively new bent-core liquid crystals, as contrasted to conventional straight-core ("calamitic") liquid crystals, have been systematically studied by dynamic light scattering. Objective: Comparison of properties of bent-core nematics with straight-core nematics and search for a biaxial nematic phase due to the bent-core shape. Observations: Nematic phases are rather uncommon in bent-core compounds because nematic structure occurs only if the molecules can rotate relatively freely around their long axis, the condition apparently met in only a fraction of bent-core materials synthesized so far. The obtained results show that the elasticity to viscosity ratio for uniaxial bent-core nematics is typically two orders of magnitude lower than for straight-core nematics, due evidently to the large viscosity associated with optic axis distortions in the bent-core case. This result is independent of the normal mode of the director fluctuations probed. In one compound polarized light scattering data reveal fluctuations associated with the biaxial order parameter, occurring as a pretransitional effect on approach to the biaxial smectic-C phase. However, results on a homeotropically-aligned sample of another compound provide preliminary light scattering evidence for nematic biaxiality. Objective: To determine nature of isotropic to nematic phase transition and to measure dielectric fluctuations in the isotropic phase near the transition. Observations: The orientational order parameter fluctuations in the isotropic phase have been studied for the first time in bent-core compounds. Analogous to classic light scattering experiments performed on calamitic liquid crystals, fluctuations in nematic order in bent-core compounds exhibit a mean-field-like critical slowing down on approach to the isotropic-nematic transition from above. The fluctuations are intrinsically several orders of magnitude slower than for typical calamitics. In two related bent-core compounds, the transition is found to be weakly first-order, with the value of T NI -T* being ~3 times lower than the value typically obtained for calamitics. This reduction could be the effect of an enhanced density change at the I-N transition in the case of bent-core mesogens.

Author: Vladimir P. Skripov
Publisher: John Wiley & Sons
ISBN: 3527607528
Category : Science
Languages : en
Pages : 183

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Professor Skripov obtained worldwide recognition with his monograph "Metastable liquids", published in English by Wiley & Sons. Based upon this work and another monograph published only in Russia, this book investigates the behavior of melting line and the properties of the coexisting crystal and liquid phase of simple substances across a wide range of pressures, including metastable states of the coexisting phases. The authors derive new relations for the thermodynamic similarity for liquid-vapour phase transition, as well as describing solid-liquid, liquid-vapor and liquid-liquid phase transitions for binary systems employing the novel methodology of thermodynamic similarity.