Structure and phase transition in self-assembled films of an anti-ferroelectric liquid crystal studied by two-dimensional correlation FTIR spectroscopy

2005 ◽  
Vol 61 (5) ◽  
pp. 905-911 ◽  
Author(s):  
Yuchuan Cheng ◽  
Xu Wang ◽  
Jianbo Cheng ◽  
Li Sun ◽  
Weiqing Xu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Ftir Spectroscopy ◽  
Ferroelectric Liquid Crystal ◽  
Two Dimensional ◽  
Self Assembled

Ferroelectric Liquid Crystal Light Valve Using SiO2 / A-Si:H Photodiode

1991 ◽  
Vol 219 ◽  
Author(s):  
T. Horikawa ◽  
S. Tahata ◽  
S. Kaho ◽  
T. Masumi ◽  
N. Mikami ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Dark Conductivity ◽  
Ferroelectric Liquid Crystal ◽  
Two Dimensional ◽  
Metal Insulator ◽  
Resolution Capability ◽  
New Type ◽  
Light Valve ◽  
Mis Diode ◽  
High Photosensitivity

ABSTRACTA new type of ferroelectric liquid crystal light valve (FLCLV) is presented. The design of the FLCLV is based upon the linear equivalent circuit analyses. A photosensor in the FLCLV consists of a metal-insulator-semiconductor (MIS) photodiode. A-Si:H doped with boron and nitrogen [a-Si:(:N:B)] is used in the MIS diode. The a-Si:H(:B:N) film has a dark-conductivity of less than 1×1012 S/cm and a high photosensitivity.Consequently, the writing characteristics of the FLCLV for a two dimensional (2D) image are evaluated. Using writing light of 630 nm and 1 mW/cm2, a high resolution capability of 120∼140 1p/mm is obtained.

Evidence for a liquid crystal phase transition in two-dimensional electrons in high Landau levels

2002 ◽  
Vol 12 (9) ◽  
pp. 377-380
Author(s):  
K. B. Cooper ◽  
M. P. Lilly ◽  
J. P. Eisenstein ◽  
L. N. Pfeiffer ◽  
K. W. West
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Landau Levels ◽  
Crystal Phase ◽  
Two Dimensional ◽  
Liquid Crystal Phase ◽  
Stripe Phase ◽  
Stripe Order ◽  
Crystal Phase Transition ◽  
Liquid Crystal Phase Transition

Transport measurements of high-mohility two-dimensional electron systems at low temperatures have revealed a large resistance anisotropy around half-filling of excited Landau levels. These results have been attributed to electronic stripe-phase formation with spontaneously broken orientational symmetry. Mechanisms which are known to break the orientational symmetry include poorly-understood crystal structure effects and an in-plane magnetic field, $B_{||}$. Here we report that a large $B_{||}$ also causes the transport anisotropy to persist up to much higher temperatures. In this regime, we find that the anisotropic resistance scales sublinearly with $B_{||}/T$. These observations support the proposal that the transition from anisotropic to isotropic transport reflects a liquid crystal phase transition where local stripe order persists even in the isotropic regime.

X-ray microdiffraction study of the half-V-shaped switching liquid crystal

2004 ◽  
Vol 19 (1) ◽  
pp. 53-55 ◽  
Author(s):  
Kazuhiro Takada ◽  
Takashi Noma ◽  
Takeshi Togano ◽  
Taihei Mukaide ◽  
Atsuo Iida
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Formation Process ◽  
Ferroelectric Liquid Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transient Layer ◽  
Smectic C ◽  
Layer Structures ◽  
Temperature Controlled

Local layer structures and their formation process in a half-V-shaped switching ferroelectric liquid crystal (HV-FLC) were investigated by means of synchrotron X-ray microdiffraction. The HV-FLC is a FLC that has a cholesteric–chiral smectic C (Ch–SmC*) phase transition sequences. X-ray microdiffraction measurements revealed that the SmC* phase in the HV-FLC was composed of asymmetric chevron and inclined-bookshelf structures. In addition, temperature-controlled X-ray diffraction measurements showed that the transient layer structures appeared during the Ch to SmC* phase transition.

Mechanism of Thermal Phase Transition of a Ferroelectric Liquid Crystal with Monotropic Transition Temperature Studied by Infrared Spectroscopy Combined with Principal Component Analysis and Sample—Sample Two-Dimensional Correlation Spectroscopy

2005 ◽  
Vol 59 (5) ◽  
pp. 620-629 ◽  
Author(s):  
Jinggang Zhao ◽  
Kenji Tatani ◽  
Yukihiro Ozaki
Keyword(s):  
Phase Transition ◽  
Principal Component ◽  
Correlation Spectroscopy ◽  
Heating Process ◽  
Ferroelectric Liquid Crystal ◽  
Two Dimensional ◽  
Thermal Dynamics ◽  
Alkyl Chains ◽  
The Core ◽  
2D Correlation Spectroscopy

Infrared (IR) spectra of FLC-154 (FLC: ferroelectric liquid crystal) with monotropic phase transition under a nonalignment state with a sample layer thickness of 24.5 μm were measured for heating process from 55 to 90 °C and a cooling process from 90 to 55 °C in increments of 1 °C. The thermal dynamics of FLC-154 were investigated by use of IR spectroscopy combined with principal component analysis (PCA) and sample–sample two-dimensional (2D) correlation spectroscopy. During the cooling, the FLC-154 molecule passes through the monotropic smectic- C* (Sm- C*) phase, which is transformed from the Sm- A phase. The results from PCA suggest that during the heating process, the thermal dynamics of the alkyl chains, core moiety, and C=O groups are similar to each other. Furthermore, PCA and sample–sample 2D correlation spectroscopy indicate that the alkyl chains and C=O groups in the chiral and core moieties are responsible for the emergence of the Sm- C* phase. This conclusion is very important because the IR data have given more evident cause for the emergence of the Sm- C* phase than the theoretical models such as the molecular-statistical theory of ferroelectric ordering and the indigenous polarization theory. Moreover, it has been found that some of the trans conformations of the alkyl chains of FLC-154 change partly to the gauche conformation when the phase transition from the crystalline phase to the Sm- A phase occurs. It has also been found that the intermolecular interactions of the C=O group in the core moiety in the Sm- A phase are weaker than those in the crystalline phase and that the conformational change occurs on the C–O–C bonds in the core moiety upon going from the crystalline to the Sm- A phase.

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