Spatially Resolved Characterization of the Electroclinic Effect in Chiral Smectic a Liquid Crystals

1996 ◽  
Vol 425 ◽  
Author(s):  
J. R. Lindle ◽  
S. R. Flom ◽  
F. J. Bartoli ◽  
A. T. Harter ◽  
R. E. Geer ◽  
...  
Keyword(s):  
Optical Properties ◽  
Angular Distribution ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Tilt Angle ◽  
X Ray ◽  
Smectic A ◽  
Spatially Resolved ◽  
Smectic A Liquid Crystals

AbstractThe electro-optical properties of an electroclinic liquid crystal have been investigated using a spatially resolved technique which measures the birefringence, optical tilt angle and extinction within adjacent stripe domains. A comparison of these results with the data obtained from standard optical and X-ray measurements suggests the presence of substripes or an angular distribution of molecular directors within the stripe domains.

Optical and electro-optical characterization of the electroclinic effect in smectic A liquid crystals

1996 ◽  
Author(s):  
James R. Lindle ◽  
A. T. Harter ◽  
Steven R. Flom ◽  
Filbert J. Bartoli ◽  
Ranganathan Shashidhar ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Optical Characterization ◽  
Smectic A ◽  
Smectic A Liquid Crystals

X-ray reflectivity of classical smectic-A liquid crystals

1988 ◽  
Vol 49 (2) ◽  
pp. 363-367 ◽  
Author(s):  
E.F. Grarnsbergen ◽  
W.H. de Jeu
Keyword(s):  
Liquid Crystals ◽  
X Ray ◽  
Smectic A ◽  
Smectic A Liquid Crystals

Effect of Side Chain Substitution on the Field-Dependent Birefringence in a Series Of Chiral Smectic a Liquid Crystals

1999 ◽  
Vol 559 ◽  
Author(s):  
J. R. Lindle ◽  
F. J. Bartoli ◽  
S. R. Flom ◽  
J. V. Selinger ◽  
R. Shashidhar ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Tilt Angle ◽  
Large Change ◽  
Side Chain ◽  
Zero Field ◽  
Strongly Correlated ◽  
Smectic A ◽  
Field Dependent ◽  
Quarter Wave ◽  
Smectic A Liquid Crystals

ABSTRACTThe field dependent birefringence and the tilt angle are measured for a series of four electroclinic liquid crystals. The zero-field birefringence decreased significantly and monotonically with the length of the siloxane side chain. For all four samples, the birefringence and the electroclinic tilt angle increased substantially with the application of a field. At 10 V/µm, the electroclinic tilt angle in DSiKN65 and TSiKN105 exceeded 22.5 degrees and the phase retardation due to the change in the birefringence exceeded a quarter wave. In all four liquid crystals, the electroclinic tilt angle and the field-dependent birefringence were shown to be strongly correlated, suggesting a common origin. Moreover, this correlation persists even at high fields where both processes undergo saturation. A simple orientational model, based on a distribution in the molecular optical axis, was developed to explain the large change in birefringence in the substituted compounds as well as the dependence of δn on electric field.

scholarly journals Chemical-Physical Characterization of a Binary Mixture of a Twist Bend Nematic Liquid Crystal with a Smectogen

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1110
Author(s):  
Abir Aouini ◽  
Maurizio Nobili ◽  
Edouard Chauveau ◽  
Philippe Dieudonné-George ◽  
Gauthier Damême ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystal ◽  
Liquid Crystalline ◽  
Smectic A ◽  
Liquid Crystalline Phases ◽  
Electro Optic ◽  
Optical Dielectric

Nematic twist-bend phases (NTB) are new types of nematic liquid crystalline phases with attractive properties for future electro-optic applications. However, most of these states are monotropic or are stable only in a narrow high temperature range. They are often destabilized under moderate cooling, and only a few single compounds have shown to give room temperature NTB phases. Mixtures of twist-bend nematic liquid crystals with simple nematogens have shown to strongly lower the nematic to NTB phase transition temperature. Here, we examined the behaviour of new types of mixtures with the dimeric liquid crystal [4′,4′-(heptane-1,7-diyl)bis(([1′,1″-biphenyl]4″-carbo-nitrile))] (CB7CB). This now well-known twist-bend nematic liquid crystal presents a nematic twist-bend phase below T ≈ 104 °C. Mixtures with other monomeric alkyl or alkoxy -biphenylcarbonitriles liquid crystals that display a smectic A (SmA) phase also strongly reduce this temperature. The most interesting smectogen is 4′-Octyl-4-biphenylcarbonitrile (8CB), for which a long-term metastable NTB phase is found at room and lower temperatures. This paper presents the complete phase diagram of the corresponding binary system and a detailed investigation of its thermal, optical, dielectric, and elastic properties.

scholarly journals Effect of ferroelectric BaTiO3 particles on the threshold voltage of a smectic A liquid crystal

2018 ◽  
Vol 9 ◽  
pp. 824-828 ◽  
Author(s):  
Abbas Rahim Imamaliyev ◽  
Mahammadali Ahmad Ramazanov ◽  
Shirkhan Arastun Humbatov
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Threshold Voltage ◽  
Strong Electric Field ◽  
Dielectric Anisotropy ◽  
Smectic A ◽  
Capacitance Voltage ◽  
Two Factors ◽  
Smectic A Liquid Crystals

The influence of small ferroelectric BaTiO3 particles on the planar–homeotropic transition threshold voltage in smectic A liquid crystals consisting of p-nitrophenyl p-decyloxybenzoate and 4-cyano-4′-pentylbiphenyl were studied by using capacitance–voltage (C–V) measurements. It was shown that the BaTiO3 particles significantly reduce the threshold voltage. The obtained result is explained by two factors: an increase of dielectric anisotropy of the liquid crystals and the formation of a strong electric field near polarized particles of BaTiO3. It was shown that the role of the second factor is dominant. The explanations of some features observed in the C–V characteristics are given.

scholarly journals Electrically driven formation and dynamics of Pac-Man solitons in smectic A liquid crystals

2021 ◽  
Author(s):  
Yuan Shen ◽  
Ingo Dierking
Keyword(s):  
Liquid Crystals ◽  
Electric Field ◽  
Spatiotemporal Chaos ◽  
Practical Applications ◽  
Smectic A ◽  
Fundamental Science ◽  
Smectic A Liquid Crystals

Electric field driven instabilities of liquid crystals, such as electro-convections, spatiotemporal chaos, backflows, and solitons are of great importance for both fundamental science and practical applications. Here we demonstrate that...

Characterization of some mesogenic alkyl 1-thioglycosides

2002 ◽  
Vol 80 (8) ◽  
pp. 1162-1165 ◽  
Author(s):  
B Henrissat ◽  
G K Hamer ◽  
M G Taylor ◽  
R H Marchessault
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Solid State ◽  
Solid State Nmr ◽  
Liquid Crystalline ◽  
Liquid Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Crystalline Phases

A series of dodecyl 1-thio-β-D-glycosides has been synthesized and characterized (DSC, NMR, CP MAS, X-ray diffraction) as possible new marking materials with liquid-crystalline properties. These compounds undergo solid to liquid crystal phase transitions at various temperatures, which depend on the nature of the carbohydrate part of the structure. Their liquid-crystalline phases show extreme shear thinning behaviour.Key words: liquid crystal, powder X-ray diffraction, phase transition, thioglycoside, solid-state NMR, marking material

THE NEMATIC-SMECTIC-A-SMECTIC-C MULTICRITICAL POINT IN BINARY LIQUID-CRYSTAL MIXTURES

1990 ◽  
Vol 04 (13) ◽  
pp. 841-845
Author(s):  
RUOZI QIU ◽  
JOHN T. HO
Keyword(s):  
Liquid Crystal ◽  
Light Scattering ◽  
Static Light Scattering ◽  
Multicritical Point ◽  
X Ray ◽  
Quasielastic Light Scattering ◽  
Binary Liquid ◽  
Smectic A ◽  
Smectic C ◽  
X Ray Scattering

Properties near the nematic-smectic-A-smectic-C multicritical point present in binary liquid-crystal mixtures are reviewed. Recent dynamic Fréedericksz deformation and quasielastic light-scattering results are described and their relationship with data from X-ray scattering and static light scattering is discussed.

Sign in / Sign up

Export Citation Format

Share Document