Theory of the Blue Phase of Cholesteric Liquid Crystals

Meiboom, S.; Sethna, James P.; Anderson, Philip W.; Brinkman, W. F.

doi:10.1103/physrevlett.46.1216

Cited by 350 publications

(240 citation statements)

References 17 publications

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“…In the traditional blue phase the defects were kept apart by the pitch of the cholesteric; here the defects are kept apart by the large energy cost of the line defects which connect them. Moreover, the traditional blue phase is stabilized by a large positive value of K 24 as opposed to the large negative value required here [7]. Though it is likely that the core energy density ε should be greatly reduced in the case of the nematic since the smectic condensation energy no longer contributes to the energy, it is possible to have a nematic phase with a periodic lattice of defects.…”

Section: Figmentioning

confidence: 99%

“…The precise physical properties of these materials have been the study of intense investigation in recent years [4,5,6]. However, there is no obvious way to incorporate smectic ordering into the traditional double-twist tube blue phase ordering put forward by Sethna et al [7] for nematic blue phases. In general, since smectic ordering is incompatible with cubic symmetry, it is expected that any blue phase structure must include smectic defects as well as orientational defects.…”

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Smectic Phases with Cubic Symmetry: The Splay Analog of the Blue Phase

DiDonna

Kamien

2002

Phys. Rev. Lett.

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We report on a construction for smectic blue phases, which have quasi-long range smectic translational order as well as long range cubic or hexagonal order. Our proposed structures fill space with a combination of minimal surface patches and cylindrical tubes. We find that for the right range of material parameters, the favorable saddle-splay energy of these structures can stabilize them against uniform layered structures.PACS numbers: 61.30. Mp, 61.30.Jf, Liquid crystalline blue phases exhibit true threedimensional, periodic orientational order. Two of these phases possess cubic symmetry (BP 1 and BP 2) while the third (BP 3) is thought to be an isotropic melt of double-twist cylinders [1,2]. Recently, new phases of matter have been identified that possess the quasi-long range translational order of smectics [3] and, at the same time, three-dimensional orientational order. These three distinct smectic blue phases have been observed near the isotropic transition of these compounds: BP sm 1 has cubic symmetry, while BP sm 2 and BP sm 3 have hexagonal symmetry. The precise physical properties of these materials have been the study of intense investigation in recent years [4,5,6]. However, there is no obvious way to incorporate smectic ordering into the traditional double-twist tube blue phase ordering put forward by Sethna et al. [7] for nematic blue phases. In general, since smectic ordering is incompatible with cubic symmetry, it is expected that any blue phase structure must include smectic defects as well as orientational defects. Though a model for double-twist cylinders with smectic order has been proposed [8], the simplest variant of that model is incompatible with experimental details [5]. In this letter, we propose a new scheme for constructing a smectic blue phase that fills space with continuous concentric layers with cubic symmetry. For this construction there are elastic energy costs arising from non-uniform layer spacing and layer bending as well as condensation energy costs arising from melted regions. However, we show that when the saddle-splay constant, K 24 , is negative enough, these energy costs can be compensated by the gain in Gaussian curvature energy in the surfaces.The key ingredient in our construction is the observation that saddle-splay and the Gaussian curvature are identical [9] for layered systems with uniform spacing. The saddle splay energy of a director field N is [7]

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Section: Figmentioning

confidence: 99%

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confidence: 99%

Smectic Phases with Cubic Symmetry: The Splay Analog of the Blue Phase

DiDonna

Kamien

2002

Phys. Rev. Lett.

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“…Blue phases provide a particularly fascinating example of liquid crystal ordering as they correspond to complicated director fields which, even in equilibrium, are threaded by a regular network of disclinations [8][9][10][11][12][13]. Identifying their structure presented a considerable theoretical challenge the resolution of which is clearly summarised in the review by Wright and Mermin [4].…”

Section: Introductionmentioning

confidence: 99%

Numerical calculations of the phase diagram of cubic blue phases in cholesteric liquid crystals

Dupuis¹,

Marenduzzo²,

Yeomans³

2005

Phys. Rev. E

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We study the static properties of cubic blue phases by numerically minimising the three-dimensional, Landau-de Gennes free energy for a cholesteric liquid crystal close to the isotropic-cholesteric phase transition. Thus we are able to refine the powerful but approximate, semi-analytic frameworks that have been used previously. We obtain the equilibrium phase diagram and discuss it in relation to previous results. We find that the value of the chirality above which blue phases appear is shifted by 20% (towards experimentally more accessible regions) with respect to previous estimates. We also find that the region of stability of the O 5 structure -which has not been observed experimentally -shrinks, while that of BP I (O − 8 ) increases thus giving the correct order of appearance of blue phases at small chirality. We also study the approach to equilibrium starting from the infinite chirality solutions and we find that in some cases the disclination network has to assemble during the equilibration.In these situations disclinations are formed via the merging of isolated aligned defects.61.30. Mp,83.80.Xz,61.30.Dk Typeset using REVT E X 1

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“…It is shown [3] that the blue phases are special cases when a "double twist" structure fill up large volumes. The double twist means structure in which the director twists simultaneously about two independent directions ( Fig.…”

Section: Introductionmentioning

confidence: 99%

Polymorphism Investigation of (4-(4'-Octylobiphenyl)carboxylane) 4-(2-Methylobuthyl) Phenol Liquid Crystal Having Blue Phase

Lewińska

Otowski

2010

Acta Phys. Pol. A

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(4-(4 -octylobiphenyl)carboxylane) 4-(2-methylobuthyl) phenol, the substance showing complex polymorphism, has been investigated using the calorimetric, microscopic and X-ray methods. This substance exhibited polymorphism during heating and cooling: a few smectic phases, a cholesteric phase and a blue phase as well. However, the substance polymorphism depends on the rate of heat flow. Existing of the blue phase has been confirmed by polarizing microscopic observations done at several temperature rates.

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Theory of the Blue Phase of Cholesteric Liquid Crystals

Cited by 350 publications

References 17 publications

Smectic Phases with Cubic Symmetry: The Splay Analog of the Blue Phase

Smectic Phases with Cubic Symmetry: The Splay Analog of the Blue Phase

Numerical calculations of the phase diagram of cubic blue phases in cholesteric liquid crystals

Polymorphism Investigation of (4-(4'-Octylobiphenyl)carboxylane) 4-(2-Methylobuthyl) Phenol Liquid Crystal Having Blue Phase

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