Liquid-hexatic phase transitions in single molecular layers of liquid-crystal films

Nature ◽  
1992 ◽  
Vol 355 (6356) ◽  
pp. 152-154 ◽  
Author(s):  
R. Geer ◽  
T. Stoebe ◽  
C. C. Huang ◽  
R. Pindak ◽  
J. W. Goodby ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Liquid Crystal ◽  
Liquid Crystal Films ◽  
Hexatic Phase ◽  
Crystal Films ◽  
Molecular Layers

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.

Thermal Property Evolution Toward Effectively Two-Dimensional Substrate-Free Systems

1989 ◽  
Vol 177 ◽  
Author(s):  
R. Geer ◽  
T. Stoebe ◽  
C. C. Huang ◽  
R. Pindak ◽  
J. Goodby
Keyword(s):  
Heat Capacity ◽  
Liquid Crystal ◽  
Adiabatic Calorimeter ◽  
Two Dimensional ◽  
Limiting Behavior ◽  
Liquid Crystal Films ◽  
Smectic A ◽  
Surface Transition ◽  
Crystal Films ◽  
Molecular Layers

ABSTRACTA high-resolution differential quasi-adiabatic calorimeter has been developed to investigate the physical properties of freestanding liquid-crystal films. Our recent heat-capacity studies near the smectic-A-hexatic-B transition of both 65OBC and 46OBC freestanding films clearly demonstrate the evolution towards twodimensional limiting behavior in four-layer films. As the film thickness decreases towards four molecular layers, the heatcapacity anomalies first display separate peaks for the surface and interior transitions and then evolve to one dominated by the surface transition.

PHYSICAL PROPERTIES OF THIN SUBSTRATE-FREE LIQUID-CRYSTAL FILMS

1995 ◽  
Vol 09 (18n19) ◽  
pp. 2285-2319 ◽  
Author(s):  
T. STOEBE ◽  
C.C. HUANG
Keyword(s):  
Liquid Crystal ◽  
Two Dimensions ◽  
Calorimetric Data ◽  
Free Standing ◽  
Liquid Crystal Films ◽  
Ideal System ◽  
Crystal Films ◽  
Optical And Mechanical Properties ◽  
Molecular Layers ◽  
Physical Phenomena

Free-standing liquid-crystal films constitute a unique and phenomenally rich system in which a number of physical phenomena may be carefully studied. In particular, they provide an ideal system in which the novel theories of defect-mediated melting in two-dimensions (2D) may be tested. Calorimetric data is presented that indicate that such theories cannot adequately account for phase transitions in effectively 2D free-standing liquid-crystal films only two molecular layers in thickness. Extensive Monte Carlo simulation studies have therefore been performed on a trial Hamiltonian that couples herringbone order to the hexatic order. In a relatively large region of parameter space, the simulation yields heat-capacity consistent with our calorimetric data. These results are discussed in the context of existing data on the structural, optical, and mechanical properties of free-standing films.

scholarly journals Analysis of the shape of x-ray diffraction peaks originating from the hexatic phase of liquid crystal films

2017 ◽  
Vol 647 (1) ◽  
pp. 169-178 ◽  
Author(s):  
I. A. Zaluzhnyy ◽  
R. P. Kurta ◽  
A. P. Menushenkov ◽  
B. I. Ostrovskii ◽  
I. A. Vartanyants
Keyword(s):  
Liquid Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Crystal Films ◽  
Hexatic Phase ◽  
Crystal Films ◽  
Diffraction Peaks

Pattern-Directed Phase Transitions and VOC Sensing of Liquid Crystal Films

2020 ◽  
Vol 59 (5) ◽  
pp. 1902-1913
Author(s):  
Ravi Bolleddu ◽  
Snigdha Chakraborty ◽  
Mitradip Bhattacharjee ◽  
Nandini Bhandaru ◽  
Siddharth Thakur ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Liquid Crystal ◽  
Liquid Crystal Films ◽  
Crystal Films
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