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Feng Z, Chandani Perera ADL, Fukuda A, Vij JK, Ishikawa K, Iida A, Takanishi Y. Definite existence of subphases with eight- and ten-layer unit cells as studied by complementary methods, electric-field-induced birefringence and microbeam resonant x-ray scattering. Phys Rev E 2017; 96:012701. [PMID: 29347082 DOI: 10.1103/physreve.96.012701] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Indexed: 06/07/2023]
Abstract
A mixture of two selenium-containing compounds, 80 wt. % AS657 and 20 wt. % AS620, are studied with two complementary methods, electric-field-induced birefringence (EFIB) and microbeam resonant x-ray scattering (μRXS). The mixture shows the typical phase sequence of Sm-C_{A}^{*}-1/3-1/2-Sm-C^{*}-Sm-C_{α}^{*}-Sm-A, where 1/3 and 1/2 are two prototypal ferrielectric and antiferroelectric subphases with three- and four-layer unit cells, respectively. Here we designate the subphase as its q_{T} number defined by the ratio of [F]/([F]+[A]), where [F] and [A] are the numbers of synclinic ferroelectric and anticlinic antiferroelectric orderings in the unit cell, respectively. The electric field vs temperature phase diagram with EFIB contours indicates the emergence of three additional subphases, an antiferroelectric one between Sm-C_{A}^{*} and 1/3 and antiferroelectric and apparently ferrielectric ones between 1/3 and 1/2. The simplest probable q_{T}'s for these additional subphases are 1/4, 2/5, and 3/7, respectively, in the order of increasing temperature. The μRXS profiles indicate that antiferroelectric 1/4 and 2/5 approximately have the eight-layer (FAAAFAAA) and ten-layer (FAFAAFAFAA) Ising unit cells, respectively. The remaining subphase may be ferrielectric 3/7 with a seven-layer unit cell, although the evidence is partial. These experimental results are compared with the phenomenological Landau model [P. V. Dolganov and E. I. Kats, Liq. Cryst. Rev. 1, 127 (2014)2168-039610.1080/21680396.2013.869667] and the quasimolecular model [A. V. Emelyanenko and M. A. Osipov, Phys. Rev. E 68, 051703 (2003)1063-651X10.1103/PhysRevE.68.051703].
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Affiliation(s)
- Zhengyu Feng
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Meguro, Tokyo 152-8552, Japan
| | - A D L Chandani Perera
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
- Department of Chemistry, University of Peradeniya, Peradeniya 20400, Sri Lanka
| | - Atsuo Fukuda
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Jagdish K Vij
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
| | - Ken Ishikawa
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Meguro, Tokyo 152-8552, Japan
| | - Atsuo Iida
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho Tsukuba, Ibaraki 305-0801, Japan
| | - Yoichi Takanishi
- Department of Physics, Faculty of Science, Kyoto University, Kitashirakawa-oiwake, Sakyou-ku, Kyoto 606-8502, Japan
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Rjili M, Gharbi A, Othman T, Marcerou JP. Effect of an external electric field on the smectic-Ctilted* phases. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:022507. [PMID: 25353489 DOI: 10.1103/physreve.89.022507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Indexed: 06/04/2023]
Abstract
We are interested in the chiral tilted smectic subphases, smectic-C(tilted)(*), including commensurate structures as well as the incommensurate smectic-C(α)(*) one. The continuum theory defines two scalar order parameters I and J, which can be coupled with an external electric field through a linear term I × E and a dielectric term J × E(2). We have calculated the changes due to these terms in the phase diagrams in the (α,η) plane, where α comes from the spontaneous twist and η measures the strength of the biaxial order. The coupling with an external electric field induces the expansion of the areas with spontaneous polarization and the appearance of an electroazimuthal effect.
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Affiliation(s)
- M Rjili
- Laboratoire de Physique de la Matière Molle et de la Modélisation Électromagnétique, Faculté des Sciences de Tunis, Université Tunis El Manar, 2092 El Manar Tunis, Tunisia
| | - A Gharbi
- Laboratoire de Physique de la Matière Molle et de la Modélisation Électromagnétique, Faculté des Sciences de Tunis, Université Tunis El Manar, 2092 El Manar Tunis, Tunisia
| | - T Othman
- Laboratoire de Physique de la Matière Molle et de la Modélisation Électromagnétique, Faculté des Sciences de Tunis, Université Tunis El Manar, 2092 El Manar Tunis, Tunisia
| | - J P Marcerou
- Centre de Recherches Paul Pascal, Université Bordeaux 1, 115, Avenue Albert-Schweitzer, 33600 Pessac, France†
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3
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Abstract
In this paper we investigate the ground state and the nature of the transition from an orientational ordered phase at low temperature to the disordered state at high temperature in a molecular crystal. Our model is a Potts model which takes into account the exchange interaction J between nearest-neighbor molecules and a dipolar interaction between molecular axes in three dimensions. The dipolar interaction is characterized by two parameters: its amplitude D and the cutoff distance r(c). If the molecular axis at a lattice site has three orientations, say the x, y or z axes, then when D = 0, the system is equivalent to the 3-state Potts model: the transition to the disordered phase is known to be of first order. When D ≠ 0, the ground-state configuration is shown to be composed of two independent interpenetrating layered subsystems which form a sandwich whose periodicity depends on D and r(c). We show by extensive Monte Carlo simulation with a histogram method that the phase transition remains of first order at relatively large values of r(c).
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Affiliation(s)
- Danh-Tai Hoang
- Laboratoire de Physique Théorique et Modélisation, Université de Cergy-Pontoise, CNRS, UMR 8089, Cergy-Pontoise, France.
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Dolganov PV, Zhilin VM, Dolganov VK, Kats EI. Field-induced transitions between multilayer phases of polar smectic liquid crystals. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:020701. [PMID: 23005711 DOI: 10.1103/physreve.86.020701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Indexed: 06/01/2023]
Abstract
Recently Wang et al. [Phys. Rev. Lett. 104, 027801 (2010)] reported the discovery of a novel multilayer phase in polar liquid crystals. The phase was unambiguously assigned to a six-layer antiferroelectric structure (Sm-C(d6)(*)) by resonant x-ray diffraction. This discovery lead to essential progress in understanding the nature of polar phases. However, more recently, Chandani et al. [Liq. Cryst. 38, 663 (2011)] in the same material clearly identified the novel phase as a ferrielectric five-layer structure (Sm-C(d5)(*)) by the electric-field-induced birefringence. This contradiction seemed to be a mystery. In this paper we show that the two experiments are in agreement. Phenomenological Landau theory of the phase transitions shows that both phases (Sm-C(d6)(*) and Sm-C(d5)(*)) exist and transform into each other in a relatively low electric field.
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Affiliation(s)
- P V Dolganov
- Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, Russia
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5
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Pan L, Huang CC. Surface-aligning field in smectic liquid-crystal films. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 84:051703. [PMID: 22181431 DOI: 10.1103/physreve.84.051703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2011] [Revised: 10/20/2011] [Indexed: 05/31/2023]
Abstract
Two modified mean-field J(1)-J(2) models are studied to explain the surface reduction of twisting power in the helical smectic-C*(α) phase in free-standing liquid crystal films. Profiles of the surface interlayer interaction are calculated from the experimental results. The calculations reveal the existence of a strong surface field and indicate that the surface field is the reason for the observed reduced twisting power near the surface region. Our results provide a quantitative study of the interlayer interactions through surface effects in smectic liquid crystals.
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Affiliation(s)
- LiDong Pan
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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6
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Marcerou JP. Continuum theory of tilted chiral smectic phases. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:061704. [PMID: 20866429 DOI: 10.1103/physreve.81.061704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Indexed: 05/29/2023]
Abstract
We show that the sequence of distorted commensurate phases observed in tilted chiral smectics is explained by the gain in electrostatic and elastic energies due to the lock-in of the unit cell to a number of layers which is the integer closest to the ratio of the helix pitch over the smectic layer thickness of the subjacent Sm-Cα∗ phase. We also explain the sign change of the helicity in the middle of the sequence by a balance between two twist sources one intrinsic and another due to the distortion of the Sm-Cα∗.
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Affiliation(s)
- J P Marcerou
- Centre de Recherches Paul Pascal, 115, Av. Albert-Schweitzer, 33600 Pessac, France.
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Susman K, Zeks B, Cepic M. Theoretical analysis of continuous pitch evolution and reversed phase sequence in antiferroelectric liquid crystals. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:031701. [PMID: 20365745 DOI: 10.1103/physreve.81.031701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Indexed: 05/29/2023]
Abstract
Recent studies reported continuous shortening of the pitch from more than four layers to less than four layers in the helicoidally modulated tilted Sm C(alpha)* phase. In a different system, the reversed phase sequence was found: the ferroelectric tilted Sm C* phase appeared below the four-layer Sm CFI2* phase upon cooling. In this contribution we quantitatively explain the behavior within the discrete phenomenological model and we found that both behaviors are the consequence of the same reason: the quadrupolar interlayer interactions.
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Affiliation(s)
- Katarina Susman
- Faculty of Education, University of Ljubljana, Ljubljana, Slovenia
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Wang S, Pan L, Pindak R, Liu ZQ, Nguyen HT, Huang CC. Discovery of a novel smectic-C{*} liquid-crystal phase with six-layer periodicity. Phys Rev Lett 2010; 104:027801. [PMID: 20366625 DOI: 10.1103/physrevlett.104.027801] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Indexed: 05/29/2023]
Abstract
We report the discovery of a new smectic-C{*} liquid-crystal phase with six-layer periodicity by resonant x-ray diffraction. Upon cooling, the new phase appears between the SmC{alpha}{*} phase having a helical structure and the SmC{d4}{*} phase with four-layer periodicity. This SmC{d6}{*} phase was identified in two mixtures which have an unusual reversed SmC{d4}{*}-SmC{*} phase sequence. The SmC{d6}{*} phase shows a distorted clock structure. Three theoretical models have predicted the existence of a six-layer phase. However, our experimental findings are not consistent with the theories.
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Affiliation(s)
- Shun Wang
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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9
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Pan L, Wang S, Hsu CS, Huang CC. Thickness dependent phase behavior of antiferroelectric liquid crystal films. Phys Rev Lett 2009; 103:187802. [PMID: 19905833 DOI: 10.1103/physrevlett.103.187802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Indexed: 05/28/2023]
Abstract
Free standing films of a liquid crystal compound with simple surface enhanced order were studied. The resultant phase diagram demonstrates that (1) the short helical pitch smectic-C(alpha)* phase disappears below a film thickness of 10 layers, and (2) the temperature window of a distorted 4 layer smectic-C(FI2)* phase increases dramatically upon decreasing film thickness. The experimental findings were attributed to the reduced dimensionality and enhanced surface effects in thin films. The results of the smectic-C(alpha)* phase are consistent with what have been reported for helically ordered magnetic thin films, with a noticeable difference due to the opposite effect of the surface on ordering in the two systems.
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Affiliation(s)
- LiDong Pan
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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10
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Dhaouadi H, Bitri N, Essid S, Soltani T, Gharbi A, Marcerou JP. Extension of the Hamaneh-Taylor model using the macroscopic polarization for the description of chiral smectic liquid crystals. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:031712. [PMID: 19905136 DOI: 10.1103/physreve.80.031712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Indexed: 05/28/2023]
Abstract
Chiral smectic liquid crystals exhibit a series of phases, including ferroelectric, antiferroelectric, and ferrielectric commensurate structures as well as an incommensurate Sm-Calpha* phase. We carried out an extension of the phenomenological model recently presented by Hamaneh and Taylor based on the distorted-clock model. The salient feature of this model is that it links the appearance of phases to a spontaneous microscopic twist: i.e., an increment alpha of the azimuthal angle from layer to layer. The balance between this twist and an orientational order parameter J gives the effective phase. We introduce a second orientational order parameter I , which physical meaning comes from the macroscopic polarization; the effect of an applied electric is also studied. We derive phase diagrams and correlate them to our experimental results under field showing the sequence of phases versus temperature and electric field in some compounds.
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Affiliation(s)
- H Dhaouadi
- Laboratoire de Physique de la Matière Molle Faculté des Sciences de Tunis, 2092 El Manar Tunis, Tunisia.
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11
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McCoy BK, Liu ZQ, Wang ST, Pan L, Wang S, Nguyen HT, Pindak R, Huang CC. Effects of doping on an unusual smectic- C*alpha-smectic-C*FI2-smectic-C* phase sequence. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 77:061704. [PMID: 18643284 DOI: 10.1103/physreve.77.061704] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Indexed: 05/26/2023]
Abstract
The compound 10OHF has a partially inverted phase sequence, unique among the series of nOHF homologous compounds and all other known liquid crystals, with the smectic-C*FI2 (SmC*FI2) phase occurring at higher temperature than the smectic-C* (SmC*) phase. We present ellipsometric data to identify the phase sequences of 9OHF, 10OHF, 11OHF, and 12OHF. Binary mixtures of 10OHF with C11, a compound with the typical phase sequence among the smectic phases, show that the unusual phase sequence of 10OHF stabilizes upon mixing and that SmC*FI2 predominates over SmC* throughout the entire mixing phase diagram. In thin films of some mixtures, surface interactions induce a reentrant SmC*FI2-SmC*-SmC*FI2 transition in the rest of the film.
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Affiliation(s)
- B K McCoy
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA and Department of Mathematics and Physics, Azusa Pacific University, Azusa, California 91702, USA
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12
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Sandhya KL, Song JK, Panarin YP, Vij JK, Kumar S. Experimental study of high-temperature smectic- C_{FI2}{ *} phase in chiral smectic liquid crystals that exhibit phase-sequence reversal. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 77:051707. [PMID: 18643087 DOI: 10.1103/physreve.77.051707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Indexed: 05/26/2023]
Abstract
We report the results of an experimental study of a recently observed phase sequence reversal of smectic-C_{FI2}{ *} [ SmC;{ *}(q_{T}=1/2); a four layer antiferroelectric] phase appearing in the temperature range above the smectic-C{ *} (SmC;{ *}) phase from the results of optical birefringence, spontaneous polarization, selective reflection, conoscopy, and dielectric spectroscopy. The SmC_{FI2}{ *} phase is observed in an antiferroelectric liquid crystalline compound, 10OHF, in a temperature range above that of SmC{ *} phase and is found to be thermodynamically monotropic, i.e., it appears only upon cooling from SmC_{alpha}{ *} phase. This is also unstable as if it is once transformed to SmC{ *} by the application of the bias, it does not return to its original state unless the sample is heated and cooled again in the absence of the bias. Nevertheless this phase is stabilized by the addition of a chiral smectic compound 9OTBBB1M7 (abbreviated as C9), having a wide temperature range of the SmC_{FI2}{ *} phase. The temperature range of the low temperature SmC{ *} decreases with increase in the concentration of C9 and for a concentration of 55 wt. %, SmC{ *} disappears and the transition takes place directly from SmC_{FI2}{ *} to the crystalline phase on cooling. The existence of such a high-temperature SmC_{FI2}{ *} phase is also supported by a phenomenological model.
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Affiliation(s)
- K L Sandhya
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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Kirchhoff J, Hirst LS. Investigation into liquid crystalline smectic-C* subphase stability using chiral and achiral dopants. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 76:051704. [PMID: 18233670 DOI: 10.1103/physreve.76.051704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Indexed: 05/25/2023]
Abstract
In this paper we investigate the influence of chiral and achiral dopants on a chiral smectic liquid crystal material, which exhibits a rich phase sequence, including the antiferroelectric phase and the three-layer intermediate smectic (SmC*FI1) phase. Using polarized optical microscopy, differential scanning calorimetry, and x-ray diffraction we find that small amounts of achiral dopant have the ability to significantly broaden the SmC*FI1 phase, whereas an oppositely-handed dopant (otherwise identical to the host material) destabilizes the phase. This work clearly indicates that bulk chirality strongly influences SmC*FI1 phase formation and that steric effects also play an important role. Interestingly, addition of the shorter achiral molecule (8CB) was observed to increase the smectic layer spacing, most likely by suppressing interdigitation of alkyl chains between adjacent smectic layers. Control of the SmC*FI1 phase width using mixtures in this way is clearly important for effective phase characterization, and could potentially lead to commercially viable materials with a stable SmC*FI1 phase over a large temperature range.
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Affiliation(s)
- J Kirchhoff
- MARTECH, Department of Physics, Florida State University, Florida 32306, USA
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Liu ZQ, McCoy BK, Wang ST, Pindak R, Caliebe W, Barois P, Fernandes P, Nguyen HT, Hsu CS, Wang S, Huang CC. Unique pitch evolution in the smectic-C+alpha phase. Phys Rev Lett 2007; 99:077802. [PMID: 17930926 DOI: 10.1103/physrevlett.99.077802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Indexed: 05/25/2023]
Abstract
Employing resonant x-ray diffraction, we observed unique pitch evolutions in the smectic-C*(alpha) phase in mixtures of two antiferroelectric liquid crystals. Our results show that the pitch in this phase continuously evolves across 4 layers, contradicting a theoretical model that predicts that the smectic-C*(FI2) phase intervenes in the smectic-C*(alpha) phase. The phase sequences we found can be explained by another model that includes one type of long-range interaction among smectic layers.
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Affiliation(s)
- Z Q Liu
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Hamaneh MB, Taylor PL. Range of interlayer interactions in smectic- C liquid crystals. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:011703. [PMID: 17358169 DOI: 10.1103/physreve.75.011703] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 08/09/2006] [Indexed: 05/14/2023]
Abstract
The fact that the elastic constant for bending a layer of smectic- C liquid crystal along its c director differs from the value for bending in the perpendicular direction has recently been shown to give rise to interactions between distant layers. The effect of this entropy-induced interaction is to favor a parallel or antiparallel alignment of the c directors in these nonadjacent layers. We calculate in detail the range and strength of this interaction in both infinite and finite samples, and find the results to depend mainly on the ratio of the average layer bending elastic constant to the layer compression modulus. At low values of this ratio, the interlayer interaction is of long range in a bulk sample, while at high values of the ratio it decays as the inverse cube of the interlayer distance. For a sample confined between rigid substrates parallel to the layers, the interaction is greatly reduced. For a free-standing film the interaction may be enhanced if the surface tension is weak, but may be diminished if the surface tension is strong.
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Affiliation(s)
- M B Hamaneh
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106-7079, USA
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Liu ZQ, Wang ST, McCoy BK, Cady A, Pindak R, Caliebe W, Takekoshi K, Ema K, Nguyen HT, Huang CC. Smectic-Calpha*-smectic-C* phase transition and critical point in binary mixtures. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 74:030702. [PMID: 17025581 DOI: 10.1103/physreve.74.030702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2006] [Indexed: 05/12/2023]
Abstract
We have investigated the smectic-Calpha*-smectic-C* (SmCalpha*-SmC*) transition in a series of binary mixtures with resonant x-ray diffraction, differential optical reflectivity, and heat capacity measurements. Results show that the phases are separated by a first-order transition that ends at a critical point. We report the observation of such a critical point. We have proposed the appropriate order parameter and obtained values of two critical exponents associated with this transition. The values of the critical exponents suggest that long-range interactions are present in the SmCalpha*-SmC* critical region.
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Affiliation(s)
- Z Q Liu
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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McCoy BK, Liu ZQ, Wang ST, Panov VP, Vij JK, Goodby JW, Huang CC. Surface-induced multiple reentrant transitions. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 73:041704. [PMID: 16711824 DOI: 10.1103/physreve.73.041704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Indexed: 05/09/2023]
Abstract
We have studied tilted surface layers in the bulk SmA temperature window of one liquid crystal using null transmission ellipsometry. Five distinct nonplanar surface structures were observed. We present analyses of the tilt and azimuthal profiles of the structures and examine the transitions between the structures. The transitions are identified as a double reentrant synclinic-anticlinic-synclinic-anticlinic transition. Meanwhile, the transitions also display reentrant ferroelectric-antiferroelectric-ferroelectric behavior.
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Affiliation(s)
- B K McCoy
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
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18
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Wang ST, Liu ZQ, McCoy BK, Pindak R, Caliebe W, Nguyen HT, Huang CC. Optical and resonant X-ray diffraction studies confirm a SmC*FI2-SmC* liquid crystal phase sequence reversal. Phys Rev Lett 2006; 96:097801. [PMID: 16606316 DOI: 10.1103/physrevlett.96.097801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Indexed: 05/08/2023]
Abstract
Employing both null transmission ellipsometry and resonant x-ray diffraction, we confirmed the SmC*FI2-SmC* phase sequence reversal in one liquid crystal compound and specially prepared binary mixtures. This phase sequence reversal was predicted by two recent theoretical advances. Moreover, the temperature range for the SmC*FI2 phase increases significantly in the mixture suggesting that such a phase sequence may exist in other compounds.
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Affiliation(s)
- S T Wang
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Jaradat S, Roberts NW, Wang Y, Hirst LS, Gleeson HF. Remarkably wide four-layer smectic phases in mixtures of liquid crystals and highly chiral dopants. ACTA ACUST UNITED AC 2006. [DOI: 10.1039/b608229g] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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