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Meier JG, Nobili M, Carlsson T, Rudquist P, Petrenko AS, Goodby JW, Brunet M, Lagerwall ST. Possible model of an antiferroelectric twist grain boundary phase. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 76:011704. [PMID: 17677468 DOI: 10.1103/physreve.76.011704] [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: 10/04/2006] [Indexed: 05/16/2023]
Abstract
Using x-ray and optical methods we have probed the structural organization of an antiferroelectric twist grain boundary phase (TGBC(a)) lying between the regular antiferroelectric smectic-C (SmC(a)* and the smectic-Q (SmQ) or isotropic phase. We find that the twist axis is everywhere perpendicular to the local smectic layer normal and that the helical superstructure is incommensurate with the smectic layer structure. The twist grain boundaries consist of a periodic lattice of alternating +1/2 and -1/2 dispirations, i.e., unit screw dislocations in combination with half unit disclinations. The molecular tilt plane is alternatingly parallel and perpendicular to the twist axis. We find that the optically measured tilt angle in the SmC(a)* phase is smaller than that measured by x rays, which is the opposite to what is found in the SmC* phase. This means that the core part tilts less than the end chains in the SmC(a)* phase, while it tilts more in the SmC* phase. On entering the TGB phase a clear decrease is measured in the tilt angle. This is explained by the elastic influence from the disclinations, which appear in this phase.
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Affiliation(s)
- J G Meier
- Department of Microelectronics and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden
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Dierking I, Rudquist P, Komitov L, Lagerwall ST, Steble B. Investigations on the Flexoelectric and Electroclinic Effect in a Cholesteric Phase with Twist Inversion. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259708046987] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- I. Dierking
- a Institut Mr Physkalische Chemie der Technischen Universität Clausthal , Amoid-Sommerferd-Str.4, D38678 , Clausthal-Zellerfeld , Germany
| | - P. Rudquist
- b Liquid Crystal Grow, Department of Physics , Chalmers Unkeislty of Technology , S-41296 , Göteborg , Sweden
| | - L. Komitov
- b Liquid Crystal Grow, Department of Physics , Chalmers Unkeislty of Technology , S-41296 , Göteborg , Sweden
| | - S. T. Lagerwall
- b Liquid Crystal Grow, Department of Physics , Chalmers Unkeislty of Technology , S-41296 , Göteborg , Sweden
| | - B. Steble
- b Liquid Crystal Grow, Department of Physics , Chalmers Unkeislty of Technology , S-41296 , Göteborg , Sweden
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Scherowsky G, Brauer B, Grünegerg K, Müller U, Komitov L, Lagerwall ST, Skarp K, Stebler B. Sign Reversal of the Spontaneous Polarization in the C* Phase of a Side-Chain Polyacrylate and Its Monomer. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259208038533] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- G. Scherowsky
- a Institut für Organische Chemie , Technische Universität Berlin , D-1000 , Berlin , Germany
| | - B. Brauer
- a Institut für Organische Chemie , Technische Universität Berlin , D-1000 , Berlin , Germany
| | - K. Grünegerg
- a Institut für Organische Chemie , Technische Universität Berlin , D-1000 , Berlin , Germany
| | - U. Müller
- a Institut für Organische Chemie , Technische Universität Berlin , D-1000 , Berlin , Germany
| | - L. Komitov
- b Physics Department , Chalmers University of Technology , S-41296 , Göteborg , Sweden
| | - S. T. Lagerwall
- b Physics Department , Chalmers University of Technology , S-41296 , Göteborg , Sweden
| | - K. Skarp
- b Physics Department , Chalmers University of Technology , S-41296 , Göteborg , Sweden
| | - B. Stebler
- b Physics Department , Chalmers University of Technology , S-41296 , Göteborg , Sweden
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Rudquist P, Lagerwall JPF, Meier JG, D'havé K, Lagerwall ST. Tilt plane orientation in antiferroelectric liquid crystal cells and the origin of the pretransitional effect. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 66:061708. [PMID: 12513306 DOI: 10.1103/physreve.66.061708] [Citation(s) in RCA: 6] [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: 05/14/2002] [Indexed: 05/24/2023]
Abstract
The optic, electro-optic, and dielectric properties of antiferroelectric liquid crystals (AFLCs) are analyzed and discussed in terms of the local tilt plane orientation. We show that the so-called pretransitional effect is a combination of two different electro-optic modes: the field-induced antiphase distortion of the antiferroelectric structure and the field-induced reorientation of the tilt plane. In the presence of a helix, the latter corresponds to a field-induced distortion of the helix. Both electro-optic modes are active only when the electric field has a component along the tilt plane. Thus, by assuring a horizontal surface-stabilized condition, where the helix is unwound by surface action and the tilt plane is everywhere parallel to the cell plates, the pretransitional effect should be suppressed. We also discuss the dielectrically active modes in AFLCs and under which circumstances they contribute to the measured dielectric permittivity.
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Affiliation(s)
- P Rudquist
- Department of Microelectronics and Nanoscience, School of Physics and Engineering Physics, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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Fazio VSU, Zauls V, Schrader S, Busson P, Hult A, Lagerwall ST, Motschmann H. Enhanced Phase-Matched Second-Harmonic Generation in a Ferroelectric Liquid Crystal Waveguide. ACTA ACUST UNITED AC 2001. [DOI: 10.1080/10587250108029958] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Schacht J, Zugenmaier P, Buivydas M, Komitov L, Stebler B, Lagerwall ST, Gouda F, Horii F. Intermolecular and intramolecular reorientations in nonchiral smectic liquid-crystalline phases studied by broadband dielectric spectroscopy. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 61:3926-3935. [PMID: 11088173 DOI: 10.1103/physreve.61.3926] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/1999] [Indexed: 05/23/2023]
Abstract
Molecular dynamics has been studied by broadband dielectric relaxation spectroscopy in the Sm-A, Sm-B, and Sm-E phases (Sm denotes smectic) of a homologous series of nonchiral stilbenes. An assignment of modes is presented based on their dependence on temperature and molecular length, and, as far as they obey the Arrhenius law, their activation energy has been determined. In general, reorientations of entire molecules around their short axis are active, whereas reorientations of entire molecules around their long axis are locked out in the Sm-E phase of shorter homologs, yet intramolecular reorientations of polar sites have been established. Strong evidence is presented for an interdependence of reorientations of entire molecules around the short and long axes within the biaxial Sm-E phase of longer homologs.
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Affiliation(s)
- J Schacht
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Strasse 4, D-38678 Clausthal-Zellerfeld, Germany
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Dierking I, Glusen B, Lagerwall ST, Ober CK. Synchrotron x-ray study of the smectic layer directional instability. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 61:1593-1598. [PMID: 11046442 DOI: 10.1103/physreve.61.1593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/1999] [Revised: 11/10/1999] [Indexed: 05/23/2023]
Abstract
We have investigated the phenomenon of field-induced smectic layer instability, as monitored by synchrotron x-ray scattering. This instability means that, upon application of time-asymmetric electric fields to chiral smectics, the layer direction seems to "rotate" locally around an axis given by the direction of the applied field. For moderate values of field amplitude and asymmetry, domains with a favored layer inclination grow at the expense of unfavored ones, while larger fields and asymmetries generally lead to a chaotic flow behavior. At moderate amplitudes, we have followed the process of the horizontal layer folding (or horizontal chevron domain formation) and the smectic C* layer reorientation of ferroelectric liquid crystals by applying symmetric and asymmetric wave forms, respectively, and performing time resolved x-ray measurements. The studies unambiguously show the formation of a horizontal (in-plane, i.e., in a plane parallel to the cell substrates) chevron domain structure from a nonoriented sample by application of a symmetric electric field of sufficient amplitude. It is then demonstrated that a transition from the horizontal chevron domain structure to an in-plane uniform smectic layer direction takes place on application of asymmetric electric wave forms. Reversal of the field asymmetry reverses the inclination direction and selects the other layer normal direction as the uniform end state. The in-plane smectic layer reorientation process is followed here as it evolves, and analyzed directly by means of x-ray scattering.
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Affiliation(s)
- I Dierking
- Department of Physics, Division of Microelectronics and Nanoscience, Chalmers University of Technology, S-41296 Goteborg, Sweden
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Giesselmann F, Zugenmaier P, Dierking I, Lagerwall ST, Stebler B, Kaspar M, Hamplová V, Glogarová M. Smectic-A*-smectic-C* transition in a ferroelectric liquid crystal without smectic layer shrinkage. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1999; 60:598-602. [PMID: 11969798 DOI: 10.1103/physreve.60.598] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/1998] [Indexed: 04/18/2023]
Abstract
The smectic layer spacing of a nonfluorinated ferroelectric liquid crystal (FLC) compound with almost no shrinkage and only minor tendency to form zigzag defects was characterized by small angle x-ray diffraction. The material lacks a nematic phase. The smectic-A*-smectic-C* phase transition was studied by measuring the thermal and electric field response of the optical tilt and the electric polarization. These properties are described very well by a Landau expansion even without introduction of a higher-order Theta(6) term. This result suggests a pure second-order phase transition far from tricriticality and differs considerably from the typical behavior of the A*-C* transition in most FLC materials.
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Affiliation(s)
- F Giesselmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Strasse 4, D-38678 Clausthal-Zellerfeld, Germany
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Rudquist P, Lagerwall JPF, Buivydas M, Gouda F, Lagerwall ST, Clark NA, Maclennan JE, Shao R, Coleman DA, Bardon S, Bellini T, Link DR, Natale G, Glaser MA, Walba DM, Wand MD, Chen XH. The case of thresholdless antiferroelectricity: polarization-stabilized twisted SmC* liquid crystals give V-shaped electro-optic response. ACTA ACUST UNITED AC 1999. [DOI: 10.1039/a900991d] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.4] [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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Rudquist P, Komitov L, Lagerwall ST. Linear electro-optic effect in a cholesteric liquid crystal. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1994; 50:4735-4743. [PMID: 9962552 DOI: 10.1103/physreve.50.4735] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Gouda F, Kuczynski W, Lagerwall ST, Matuszczyk M, Matuszczyk T, Skarp K. Determination of the dielectric biaxiality in a chiral smectic-C phase. Phys Rev A 1992; 46:951-958. [PMID: 9908196 DOI: 10.1103/physreva.46.951] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Gouda F, Carlsson T, Flatichler K, Komitov L, Lagerwall ST, Skarp K, Stebler B. Soft-mode dielectric anomaly of a chiral smectic-B liquid crystal with sign reversal in the electroclinic response. Phys Rev A 1992; 45:R5362-R5365. [PMID: 9907730 DOI: 10.1103/physreva.45.r5362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Filipic C, Carlsson T, Levstik A, Zeks B, Blinc R, Gouda F, Lagerwall ST, Skarp K. Dielectric properties near the smectic-C-smectic-A phase transition of some ferroelectric liquid-crystalline systems with a very large spontaneous polarization. Phys Rev A Gen Phys 1988; 38:5833-5839. [PMID: 9900324 DOI: 10.1103/physreva.38.5833] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Dahl I, Lagerwall ST, Skarp K. Simple model for the polarization reversal current in a ferroelectric liquid crystal. Phys Rev A Gen Phys 1987; 36:4380-4389. [PMID: 9899394 DOI: 10.1103/physreva.36.4380] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Nounesis G, Huang CC, Pitchford T, Hobbie E, Lagerwall ST. Heat-capacity studies near the smectic-A-smectic-C phase transition of azoxy-4,4(')-di-undecyl- alpha -methylcinnamate (AMC-11). Phys Rev A Gen Phys 1987; 35:1441-1443. [PMID: 9898292 DOI: 10.1103/physreva.35.1441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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