Download or read book Flexoelectricity in Liquid Crystals written by Agnes Buka and published by World Scientific. This book was released on 2013 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.

Download or read book Flexoelectric Liquid Crystals and Their Applications written by Yingfei Jiang and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals are widely used in flat panel displays and smart windows. In flat panel display application, one way to improve the efficiency is to decrease the driving frequency when static images are displayed. As the driving frequency is decreased, the transmittance of the display may vary with time, a phenomenon known as flickering. We carried out both experimental and simulation studies to investigate the origins that cause the flickering problem. Our results show that flexoelectric effect and ions in the liquid crystal are the main factors responsible for the flickering. We quantitatively analyzed the flickering caused by the two factors. The ionic effect can be eliminated by using the fluorinated liquid crystals with high resistivity. The flexoelectric effect is attributed to the intrinsic flexoelectric coefficient of the liquid crystal and nonuniformity of the liquid crystal director configurations. We demonstrated that polymer stabilization can smooth the spatial variation of the liquid crystal orientation, while doping a liquid crystal dimer can reduce the flexoelectric coefficient of the liquid crystal. Using these methods we are able to reduce the flickering significantly. Radiant energy-flow control and privacy control are two important features for smart windows (or glass). Current smart window technologies can, however, only control one of them: radiant energy flow or privacy. Therefore, a dual-mode smart window is highly desirable. We developed a dual-mode switchable liquid-crystal window that can control both radiant energy flow and privacy. The switchable liquid-crystal window makes use of dielectric and flexoelectric effects. In the absence of an applied voltage, the window is clear and transparent, and radiant energy can flow through it and the scenery behind the window can be seen. When a low-frequency (50 Hz) voltage is applied, the window is switched to an optical scattering and absorbing state by a flexoelectric effect, and thus, privacy is protected. When a high-frequency (1 kHz) voltage is applied, the window is switched to an optical absorbing but nonscattering state through a dielectric effect, and thus, radiant energy flow is controlled. Smart windows can be categorized mainly into two types according to the operation principle: electrical switchable window and thermal switchable windows. In the electric switchable window, voltage must be applied to switch the window, which consumes energy and is not environmentally friendly. Therefore, a power-free smart window is highly demanded. We developed a thermal switchable smart window that is sensitive to ambient temperature. The window is based on a liquid crystal whose orientation imposed by an alignment layer varies with temperature. The liquid crystal layer is sandwiched between two parallel polarizers to make the window. At high temperature, the liquid crystal is aligned parallel to the cell substrate and rotates the polarization of the incident light after the first polarizer by 90o such that incident light is completely absorbed by the second polarizer, and the transmittance of the window is 0. When temperature is decreased, the liquid crystal is tilted toward the cell substrate normal and rotates the polarization of the incident light less so that some light can pass the second polarizer, and the transmittance of the window increases. When temperature is decreased below a critical value, the liquid crystal is aligned perpendicular to the cell substrate and does not rotate the polarization of the incident light such that all light passes the second polarizer, and the transmittance reaches a maximum.

Download or read book Flexoelectricity in Liquid Crystals written by Daniel Jackson and published by . This book was released on 2007 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamentals of Liquid Crystal Devices written by Deng-Ke Yang and published by John Wiley & Sons. This book was released on 2014-12-03 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid Crystal Devices are crucial and ubiquitous components of an ever-increasing number of technologies. They are used in everything from cellular phones, eBook readers, GPS devices, computer monitors and automotive displays to projectors and TVs, to name but a few. This second edition continues to serve as an introductory guide to the fundamental properties of liquid crystals and their technical application, while explicating the recent advancements within LCD technology. This edition includes important new chapters on blue-phase display technology, advancements in LCD research significantly contributed to by the authors themselves. This title is of particular interest to engineers and researchers involved in display technology and graduate students involved in display technology research. Key features: Updated throughout to reflect the latest technical state-of-the-art in LCD research and development, including new chapters and material on topics such as the properties of blue-phase liquid crystal displays and 3D liquid crystal displays; Explains the link between the fundamental scientific principles behind liquid crystal technology and their application to photonic devices and displays, providing a thorough understanding of the physics, optics, electro-optics and material aspects of Liquid Crystal Devices; Revised material reflecting developments in LCD technology, including updates on optical modelling methods, transmissive LCDs and tunable liquid crystal photonic devices; Chapters conclude with detailed homework problems to further cement an understanding of the topic.

Download or read book Electro optic studies of the flexoelectric effect in chiral nematic liquid crystals written by Bronje Musgrave and published by . This book was released on 2000 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of Flexoelectric Effect on Director Alignment of Nematic Liquid Crystals in Axial Arrangement Cylindrical Cells written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : A positive nematic liquid crystal (5CB) sample is confined in cylindrical cells under strong or weak axial anchoring boundary conditions when a radial nonuniform low-frequency electric field is applied and the flexoelectric effect is taken into account. Based on the Frank elastic free energy, the surface energy of the Rapini–Papoular approximation, the polarization free energy and the flexoelectric free energy caused by electric field, we obtain the free energy density of the nematic and solve the corresponding Euler–Lagrange equation numerically. We investigate the director distribution, the critical voltage and the critical exponent of nematic liquid crystal in cylindrical cells. It follows that the critical exponent is the classical one. It is also shown that the critical voltage in the system is affected by the flexoelectric effect, the geometric effect and radial weak anchoring effect on the cylindrical surfaces. A new type of director transition caused by the flexoelectric effect, the dielectric coupling effect and the radial weak anchoring effect is found.

Download or read book An Elementary Course On The Continuum Theory For Nematic Liquid Crystals written by Giovanni Barbero and published by World Scientific Publishing Company. This book was released on 2000-10-27 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book was written to enable physicists and engineers to learn, within a single course, some topics in variational calculus, theory of elasticity, molecular models, and surface properties of nematic materials. It prepares graduate students for studies that require a simple knowledge in the physics of nematic liquid crystals.With this consideration in mind, the authors have formulated the problems concerning the continuum theory of liquid crystals into a precise form. In working out the solutions, they have analyzed, systematically and naturally, the techniques and methods of variational calculus. Special attention is dedicated to the analysis of well-posed and ill-posed variational problems. The presence of sub-surface discontinuity in the nematic orientation is analyzed using different techniques. A full chapter is devoted to this aspect of the theory of elasticity of nematic media.

Download or read book Flexoelectricity in Nematic Liquid Crystals written by Claudius Kischka and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Flexoelectricity in liquid crystals is thought to be due to a coupling between dielectric properties and shape anisotropy of the molecules and described by the fiexoelectric coefficients el and e3. Two experiments are needed to measure el and e3 and it is usual to measure the difference (el - e3) and the sum (el + e3) and then calculate el and e3· The first experiment to measure the difference (el - e3) uses a TN structure with an in-plane applied electric field. Due to the dielectric coupling, the director aligns with the electric field and due to the fiexoelectric effect, the director tilts out of plane. This tilt is measured optically using two laser beams at oblique incidence, e.g. 45°. Using a theoretical model the experimental data is fitted and the difference (el - e3) extracted. The second experiment to measure the sum (el + e3) uses a Pi cell. Applying an ac voltage the transmission through the device is a repeating oscillating signal which contains 1st and 2nd harmonics. The 1st harmonic corresponds to the fiexoelectric effect and the 2nd harmonic to the dielectric effect. Using a lock-in amplifier, the harmonics were measured and the sum (el + e3) extracted using a theoretical model to fit the experimental data. Unfortunately, the data proved the experiment to be unreliable and another method was developed, which uses a BAN cell. The third experiment uses simple pulses in a BAN cell and also measures the sum (el + e3). The big disadvantage of the BAN cell is an internal voltage, which is created by the homeotropic alignment layer and the fiexoelectric polarisation. The internal voltage has the same effect on the director profile as the fiexoelectric effect, which is a big problem in measuring fiexoelectricity. Using a material, which is non ionic and has no fiexoelectricity, the internal bias could be measured and taken into account. Applying short de pulses of opposite sign, the fiexoelectric effect can be observed by the optical response and can be measured. Using these experiments, a number of investigation are being carried out such as the correlation between fiexoelectricity and the molecular structure, ions, elastic properties, molecular orientation, dielectric anisotropy 6E, and order parameter S. The results showed that fiexoelectricity only depends on ions and dielectric properties which was very interesting and surprising at the same time.

Download or read book Fluids Colloids and Soft Materials written by Alberto Fernandez-Nieves and published by John Wiley & Sons. This book was released on 2016-05-09 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a compilation of self-contained chapters covering a wide range of topics within the broad field of soft condensed matter. Each chapter starts with basic definitions to bring the reader up-to-date on the topic at hand, describing how to use fluid flows to generate soft materials of high value either for applications or for basic research. Coverage includes topics related to colloidal suspensions and soft materials and how they differ in behavior, along with a roadmap for researchers on how to use soft materials to study relevant physics questions related to geometrical frustration.

Download or read book Geometric Methods in the Elastic Theory of Membranes in Liquid Crystal Phases written by Zhong-Can Ou-Yang and published by World Scientific. This book was released on 1999 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a comprehensive description of the mechanical equilibrium and deformation of membranes as a surface problem in differential geometry. Following the pioneering work by W Helfrich, the fluid membrane is seen as a nematic or smectic ? A liquid crystal film and its elastic energy form is deduced exactly from the curvature elastic theory of the liquid crystals. With surface variation the minimization of the energy at fixed osmotical pressure and surface tension gives a completely new surface equation in geometry that involves potential interest in mathematics. The investigations of the rigorous solution of the equation that have been carried out in recent years by the authors and their co-workers are presented here, among which the torus and the discocyte (the normal shape of the human red blood cell) may attract attention in cell biology. Within the framework of our mathematical model by analogy with cholesteric liquid crystals, an extensive investigation is made of the formation of the helical structures in a tilted chiral lipid bilayer, which has now become a hot topic in the fields of soft matter and biomembranes.

Download or read book Electrooptic Effects in Liquid Crystal Materials written by L.M. Blinov and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrooptic effects provide the basis for much liquid-crystal display technology. This book, by two of the leaders in liquid-crystal research in Russia, presents a complete and accessible treatment of virtually all known phenomena occurring in liquid crystals under the influence of electric fields.

Download or read book Investigation of Flexoelectricity and Ionic Contamination in Nematic Liquid Crystals written by Christophe Lionel Trabi and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flexoelectricity in Liquid Crystal Materials written by Akhshay S. Bhadwal and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bent Shaped Liquid Crystals written by Hideo Takezoe and published by CRC Press. This book was released on 2017-07-20 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Ferroelectric and Antiferroelectric Liquid Crystals written by Sven T. Lagerwall and published by John Wiley & Sons. This book was released on 2008-07-11 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of ferroelectricity is a branch of solid state physics which has shown rapid growth during the recent years. Ferroelectric materials exhibit unusual electric properties which make them useful in modern (opto)electronic technology, esp. display technology. Ferroelectric and antiferroelectric liquid crystals, including also various polymer forms, are the hottest research topic today in liquid crystals. The field is at the very beginning of industrial exploitation - a sensitive phase in which a good reference work is needed and will have a broad spectrum of readers both at universities and in industry.

Download or read book Nematic and Cholesteric Liquid Crystals written by Patrick Oswald and published by CRC Press. This book was released on 2005-02-28 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals allow us to perform experiments that provide insight into fundamental problems of modern physics, such as phase transitions, frustration, elasticity, hydrodynamics, defects, growth phenomena, and optics (linear and non linear). This excellent volume meets the need for an up-to-date text on liquid crystals.Nematic and Cholesteric Liq

Download or read book Nuclear Magnetic Resonance Spectroscopy of Liquid Crystals written by Ronald Y. Dong and published by World Scientific. This book was released on 2010 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: This edited volume provides an extensive overview of how nuclear magnetic resonance can be an indispensable tool to investigate molecular ordering, phase structure, and dynamics in complex anisotropic phases formed by liquid crystalline materials. The chapters, written by prominent scientists in their field of expertise, provide a state-of-the-art scene of developments in liquid crystal research. The fantastic assortment of shape anisotropy in organic molecules leads to The discoveries of interesting new soft materials made at a rapid rate which not only inject impetus to address the fundamental physical and chemical phenomena, but also the potential applications in memory, sensor and display devices. The review volume also covers topics ranging from solute studies of molecules in nematics and biologically ordered fluids to theoretical approaches in treating elastic and viscous properties of liquid crystals. This volume is aimed at graduate students, novices and experts alike, and provides an excellent reference material for readers interested in the liquid crystal research. it is, indeed, a reference book for every science library to have.