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Journal ArticleDOI

Pretransitional Phenomena in the Isotropic Phase of a Nematic Liquid Crystal

24 Aug 1970-Physical Review Letters (American Physical Society)-Vol. 25, Iss: 8, pp 503-506
TL;DR: In this article, the authors have observed a divergence of the magnetic birefringence, and a critical increase and slowing of the fluctuations in order in the isotropic phase of a nematic liquid crystal.
Abstract: We have observed a divergence of the magnetic birefringence, and a critical increase and slowing of the fluctuations in order in the isotropic phase of a nematic liquid crystal. Our results are quantitatively described by a mean-field model except for a critical region close to the ordering temperature where the fluctuations are so large that the meanfield approximation fails.
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Journal ArticleDOI
TL;DR: In this article, the physical properties of nematic, cholesteric, and smectic liquid crystals are discussed and a wide variety of phenomena in liquid crystals, including elastic distortions, disclinations, flow properties, fluctuations, light scattering, wave propagation, nuclear magnetic resonance, effects of magnetic and electric fields, electrohydrodynamics, and optical properties.
Abstract: This review discusses the physical properties of nematic, cholesteric, and smectic liquid crystals. Molecular theories of the liquid crystal phases are discussed and the molecular field theories of the phase transitions between the various liquid crystal phases are presented. The elastic theory and hydrodynamics of liquid crystals is developed. A wide variety of phenomena in liquid crystals, including elastic distortions, disclinations, flow properties, fluctuations, light scattering, wave propagation, nuclear magnetic resonance, effects of magnetic and electric fields, electrohydrodynamics, and optical properties, is discussed.

978 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a pedagogical introduction to the current understanding of the equilibrium structure of cholesteric liquid crystals accompanied by a general overview of major experimental results.
Abstract: The blue phases of cholesteric liquid crystals are liquids that exhibit orientational order characterized by crystallographic space-group symmetries. We present here a pedagogical introduction to the current understanding of the equilibrium structure of these phases accompanied by a general overview of major experimental results. Using the Ginzburg-Landau free energy appropriate to the system, we first discuss in detail the character and stability of the usual helical phase of cholesterics, showing that for certain parameter ranges the helical phase is unstable to the appearance of one or more blue phases. The two principal models for the blue phases are two limiting cases of the Ginzburg-Landau theory. We explore each limit and conclude with some general considerations of defects in both models and an exact minimization of the free energy in a curved three-dimensional space.

560 citations

Journal ArticleDOI
Ivan Haller1

498 citations

Journal ArticleDOI
TL;DR: A comprehensive overview of phase transition studies can be found in this article, where the authors identify the essential key concepts and points of difficulty associated with the study of phase transitions and discuss the most widely used experimental techniques for measuring these transition properties.

308 citations

Journal ArticleDOI
TL;DR: A review of the wide variety of predictions that results from a Landau-type of description of the nematic-isotropic phase transition is given in this paper, which includes a discussion of the nature of the order parameter and of the various types of possible phases.

291 citations