Development of nematic and orthogonal smectic phases in short-core fluorinated hockey-stick shaped liquid crystal compounds

2020 ◽  
Vol 298 ◽  
pp. 111989
Author(s):  
Kalpana Upadhyaya ◽  
Sharmistha Ghosh ◽  
Raj Kumar Khan ◽  
R. Pratibha ◽  
Nandiraju V.S. Rao
Keyword(s):  
Liquid Crystal ◽  
Hockey Stick ◽  
Smectic Phases ◽  
Short Core

Freeze-fracture TEM of the helical smectic A* phase

1992 ◽  
Vol 50 (1) ◽  
pp. 278-279
Author(s):  
K.J. Ihn ◽  
R. Pindak ◽  
J. A. N. Zasadzinski
Keyword(s):  
Liquid Crystal ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Freeze Fracture ◽  
Smectic Phase ◽  
Layer Spacing ◽  
Screw Dislocations ◽  
Smectic A ◽  
Smectic Phases ◽  
Discrete Amount

A new liquid crystal (called the smectic-A* phase) that combines cholesteric twist and smectic layering was a surprise as smectic phases preclude twist distortions. However, the twist grain boundary (TGB) model of Renn and Lubensky predicted a defect-mediated smectic phase that incorporates cholesteric twist by a lattice of screw dislocations. The TGB model for the liquid crystal analog of the Abrikosov phase of superconductors consists of regularly spaced grain boundaries of screw dislocations, parallel to each other within the grain boundary, but rotated by a fixed angle with respect to adjacent grain boundaries. The dislocations divide the layers into blocks which rotate by a discrete amount, Δθ, given by the ratio of the layer spacing, d, to the distance between grain boundaries, lb; Δθ ≈ d/lb (Fig. 1).

Induced Smectic Phases II. Influence of the Amino Substituent on the Induction of Smectic Phases

1981 ◽  
Vol 36 (10) ◽  
pp. 1086-1091 ◽  
Author(s):  
F. Schneider ◽  
N. K. Sharma
Keyword(s):  
Liquid Crystal ◽  
Electron Donor ◽  
Amino Group ◽  
Donor Property ◽  
Smectic Phases ◽  
Ct Complexes ◽  
Induced Smectic Phases

The diagrams of state have been studied for some liquid crystal mixtures which show the induction of smectic phases. Each of the systems studied contains one component with an amino group which influences the polarity and the electron donor property of the molecules. The discussion of the diagrams of state, of the thickness of the smectic layers and of the colours of the mixtures, which indicate the formation of CT complexes, shows that existing models can not explain the induction of smectic phases.

scholarly journals Polar Switching and Cybotactic Nematic Ordering in 1,3,4-Thiadiazole-Based Short-Core Hockey Stick-Shaped Fluorescent Liquid Crystals

ACS Omega ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 7711-7722 ◽  
Author(s):  
Sandip Kumar Saha ◽  
Golam Mohiuddin ◽  
Manoj Kumar Paul ◽  
Santosh Prasad Gupta ◽  
Raj Kumar Khan ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Hockey Stick ◽  
Nematic Ordering ◽  
Short Core

Pseudo-polar tilted smectic phases exhibited by bent-core hockey stick shaped molecules

Soft Matter ◽  
2016 ◽  
Vol 12 (22) ◽  
pp. 4960-4966 ◽  
Author(s):  
Deepshika Malkar ◽  
B. K. Sadashiva ◽  
Arun Roy
Keyword(s):  
Hockey Stick ◽  
Smectic Phases

INFLUENCE OF DIMENSIONALITY AND SURFACE ORDERING ON PHASE TRANSITIONS: STUDIES OF FREELY-SUSPENDED LIQUID-CRYSTAL FILMS

1994 ◽  
Vol 08 (22) ◽  
pp. 3051-3082 ◽  
Author(s):  
CHRISTIAN BAHR
Keyword(s):  
Phase Transitions ◽  
Liquid Crystal ◽  
Two Dimensions ◽  
Smectic Liquid Crystals ◽  
Liquid Crystal Films ◽  
Integral Number ◽  
Smectic Phases ◽  
Crystal Films ◽  
Freely Suspended ◽  
Freely Suspended Films

Freely-suspended films of smectic liquid crystals can be regarded as membranes consisting of a stack of an integral number of molecular (smectic) layers with the layer planes being parallel to the two free surfaces. Because of their variable thickness (between thousands and only two layers) and the large variety of phase transitions between different smectic phases, freely-suspended films are excellent systems to study the influence of the dimensional cross-over from three to two dimensions on phase transitions. Further, because the free surface of a liquid crystal has a strong ordering effect (contrary to solids which exhibit generally surface-induced disorder), freely-suspended films are well-suited for the study of the effect of enhanced surface order on phase transitions. A review of the corresponding experimental work is given.

Ferroelektrische Flüssigkristall - Mischungen mit Kohlenhydrat - Derivaten als Dotierstoffe / Ferroelectric Liquid Crystal Mixtures with Carbohydrate Derivates as Dopants

1989 ◽  
Vol 44 (7) ◽  
pp. 675-679 ◽  
Author(s):  
V. Vill ◽  
F. Fischer ◽  
J. Thiem
Keyword(s):  
Liquid Crystal ◽  
Chiral Center ◽  
Ferroelectric Liquid Crystal ◽  
Fast Switching ◽  
Switching Times ◽  
Smectic Phases ◽  
First Time ◽  
Helical Twisting Power

Abstract For the first time carbohydrate derivatives were studied as dopants for calamitic smectic phases. Fast switching ferroelectric cells could be realized, and electroclinic effects were observed. By inversion of configuration at a chiral center of these compounds switching times, solubility, and helical twisting power vary by orders of magnitude. The studied derivatives showed modest solubility properties.

Symmetric bent-shaped liquid crystal dimers showing transitions between optically uniaxial and biaxial smectic phases

2015 ◽  
Vol 42 (7) ◽  
pp. 1013-1023 ◽  
Author(s):  
Claudia M. Hegguilustoy ◽  
Maria B. Darda ◽  
Rosana S. Montani ◽  
Benoît Heinrich ◽  
Bertrand Donnio ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Smectic Phases

Structural studies of nematic and smectic phases

1983 ◽  
Vol 309 (1507) ◽  
pp. 145-153 ◽  
Keyword(s):  
Liquid Crystal ◽  
Mean Field ◽  
Structural Studies ◽  
X Ray ◽  
Smectic A ◽  
Smectic C ◽  
X Ray Scattering ◽  
Smectic Phases ◽  
Crystal Phases ◽  
Field Behaviour

The information about liquid crystal phases that can be obtained by light scattering and by high-resolution X-ray scattering is reviewed. Results for the nematic-smectic A transition suggest the de Gennes-McMillan model is correct, but adequate theoretical solutions to the model remain elusive. Recent results on the smectic A to smectic C transition are presented that show unambiguously that it exhibits classic mean-field behaviour and this is explained by a Ginzburg criterion argument. Some preliminary results of a study of a nematic-smectic A transition in a lyotropic material are given and indicate similarity to thermotropic materials.

Induced smectic phases of stoichiometric liquid crystal mixtures

Soft Matter ◽  
2016 ◽  
Vol 12 (12) ◽  
pp. 3103-3109 ◽  
Author(s):  
Shin-ya Sugisawa ◽  
Yuka Tabe
Keyword(s):  
Liquid Crystal ◽  
Smectic Phases ◽  
Induced Smectic Phases
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