X-ray critical scattering study of nematic-smectic A phase transition in a 8DBT/120CB mixture

1988 ◽  
Vol 105 (2) ◽  
pp. K107-K110 ◽  
Author(s):  
B. Pura ◽  
J. Przedmojski ◽  
K. Wentowska ◽  
R. D??browski ◽  
K. Czupryński
Keyword(s):  
Phase Transition ◽  
X Ray ◽  
Smectic A ◽  
Smectic A Phase ◽  
Scattering Study

Structure and Thermal Behaviour of a Thermotropic Liquid Crystalline Polyimide (PI-LC)

1998 ◽  
Vol 10 (1) ◽  
pp. 147-153 ◽  
Author(s):  
M Tanaka ◽  
M Konda ◽  
M Miyamoto ◽  
Y Kimura ◽  
A Yamaguchi
Keyword(s):  
Phase Transition ◽  
Thermal Analysis ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Isotropic Phase ◽  
X Ray ◽  
Smectic A ◽  
Smectic C ◽  
Smectic A Phase

Anomalous solid structures formed by a thermotropic liquid crystalline polyimide (PI-LC) were investigated by thermal analysis, polarized light microscopy and x-ray analysis. It was revealed that PI-LC should undergo a phase transition from the crystalline to the isotropic phase through the smectic or nematic phase in the temperature range 277–300 °C. The PI-LC filament extruded at 280 °C, at which temperature the polymer was in liquid crystalline phase, was formed to have a structure similar to the smectic C phase, while that extruded and melt-drawn at 310 °C, at which temperature the polymer was in the isotropic phase, had a structure similar to the smectic A phase.

Structure and Phase Transitions in Partially Confined Smectic Liquid Crystals

1996 ◽  
Vol 464 ◽  
Author(s):  
L. J. Martinez-Miranda ◽  
Yushan Shi ◽  
Satyendra Kumar
Keyword(s):  
Phase Transition ◽  
Structural Evolution ◽  
Smectic Liquid Crystals ◽  
Layer Spacing ◽  
X Ray ◽  
First Order ◽  
Smectic A ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Partial Confinement

ABSTRACTWe present the results of an X-ray scattering study on partially confined smectic-A (layered) LC films. This partial confinement is achieved by placing the LC material inside the open grooves of a glass grating. Samples prepared in this manner are confined in the direction perpendicular to the gratings. Samples in which the LC is contained entirely inside the grooves develop an induced molecular tilt, which results in a compression of the smectic layers. The molecular tilt varies as the amount of the LC material increases, eventually forming a thin overlayer film above the gratings. As the thickness varies, a second region develops in the films. The layer spacing in this region is close to the bulk layer spacing. This structural evolution is coupled to a variation in the nematic-to-smectic-A phase transition temperature of the samples from the bulk. In addition, the nature of the phase transition is driven first order. The effects of partial confinement on a sm-C* LC film is discussed briefly.

INDUCED CHANGES OF THERMOTROPIC PROPERTIES OF PHASE TRANSITIONS BETWEEN SMECTIC A MESOPHASE AND ISOTROPIC LIQUID: EFFECT OF SURFACES

2006 ◽  
Vol 20 (14) ◽  
pp. 821-833 ◽  
Author(s):  
ARIF NESRULLAJEV ◽  
ŞENER OKTIK
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transition ◽  
Phase Transitions ◽  
Isotropic Liquid ◽  
Smectic A ◽  
Phase Transition Temperatures ◽  
Smectic A Phase ◽  
Induced Changes ◽  
Thermotropic Properties

In this work, the effect of thin films on the thermotropic and thermo-optical properties and peculiarities of the phase transitions between the smectic A and isotropic liquid have been investigated. Peculiarities of the heterophase regions of the straight smectic A-isotropic liquid and reverse isotropic liquid-smectic A phase transitions have been studied. Change of morphologic properties of the heterophase regions, shift of the phase transition temperatures and the change of temperature widths of these heterophase regions under thin film influence have been observed.

Studies of critical behaviour at the nematic to smectic A phase transition in C6 and C7 binary mixture system

2008 ◽  
Vol 41 (6) ◽  
pp. 062002 ◽  
Author(s):  
SeungYeon Jeong ◽  
DongWoo Kim ◽  
KungWon Rhie ◽  
MunPyo Hong ◽  
Satyendra Kumar ◽  
...  
Keyword(s):  
Phase Transition ◽  
Binary Mixture ◽  
Critical Behaviour ◽  
Smectic A ◽  
Smectic A Phase ◽  
Mixture System

scholarly journals Optical Microscopy Observations and Construction of Dupin Cyclides at the Isotropic/Smectic A Phase Transition

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4539
Author(s):  
Mikhael Halaby Macary ◽  
Gauthier Damême ◽  
Antoine Gibek ◽  
Valentin Dubuffet ◽  
Benoît Dupuy ◽  
...  
Keyword(s):  
Phase Transition ◽  
Numerical Simulation ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Smectic A ◽  
Polarized Microscopy ◽  
Smectic A Phase ◽  
Dupin Cyclides

In this work, we are interested in the nucleation of bâtonnets at the Isotropic/Smectic A phase transition of 10CB liquid crystal. Very often, these bâtonnets are decorated with a large number of focal conics. We present here an example of a bâtonnet obtained by optical crossed polarized microscopy in a frequently observed particular area of the sample. This bâtonnet presents bulges and one of them consists of a tessellation of ellipses. These ellipses are two by two tangent, one to each other, and their confocal hyperbolas merge at the apex of the bâtonnet. We propose a numerical simulation with Python software to reproduce this tiling of ellipses as well as the shape of the smectic layers taking the well-known shape of Dupin cyclides within this particular bâtonnet area.

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