The effect of quasispherical, chainlike, and rodlike solutes on nematic-isotropic and smectic A- nematic phase equilibria in p-n-octyl-p'-cyanobiphenyl liquid crystal

1987 ◽  
Vol 91 (25) ◽  
pp. 6410-6414 ◽  
Author(s):  
Samir. Ghodbane ◽  
Daniel E. Martire
Keyword(s):  
Liquid Crystal ◽  
Phase Equilibria ◽  
Nematic Phase ◽  
Smectic A

Effects of the preparing condition of a polymer-stabilised liquid crystal with a smectic-A−chiral nematic phase transition on its properties

2009 ◽  
Vol 36 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Guohui Pan ◽  
Yubo Cao ◽  
Renwei Guo ◽  
Huicong Cheng ◽  
Zhou Yang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Nematic Phase ◽  
Smectic A ◽  
Chiral Nematic

Effects on thermo‐optical properties of the composition of a polymer‐stabilised liquid crystal with a smectic A–chiral nematic phase transition

2008 ◽  
Vol 35 (9) ◽  
pp. 1151-1160 ◽  
Author(s):  
Guohui Pan ◽  
Lilong Yu ◽  
Hongbin Zhang ◽  
Jinbao Guo ◽  
Renwei Guo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Nematic Phase ◽  
Smectic A ◽  
Chiral Nematic

scholarly journals Hydrophobic gold nanoparticles via silane conjugation: chemically and thermally robust nanoparticles as dopants for nematic liquid crystals

2013 ◽  
Vol 371 (1988) ◽  
pp. 20120256 ◽  
Author(s):  
Javad Mirzaei ◽  
Martin Urbanski ◽  
Heinz-S. Kitzerow ◽  
Torsten Hegmann
Keyword(s):  
Phase Transition ◽  
Gold Nanoparticles ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Threshold Voltage ◽  
Nematic Phase ◽  
Dielectric Anisotropy ◽  
Smectic A ◽  
Gold Nps ◽  
First Time

We examine for the first time how chemically and thermally stable gold nanoparticles (NPs), prepared by a silane conjugation approach, affect both the thermal and the electro-optical properties of a nematic liquid crystal (LC), when doped at concentrations ranging from 0.25 to 7.5 wt%. We find that the octadecylsilane-conjugated gold NPs stabilize both the enantiotropic nematic and the monotropic smectic-A phases of the LC host with a maximum stabilization of 2 ° C for the nematic and 3.5 ° C for the smectic-A phases for the mixture containing 1 wt% of the silanized particles. The same mixture shows the lowest values for the Fréedericksz transition threshold voltage and the highest value for the dielectric anisotropy. Generally, all NP-containing mixtures, except mixtures with NP concentrations exceeding 5 wt%, reduce the threshold voltage, increase the dielectric anisotropy and reduce both rise and decay time; the latter particularly at temperatures at least 10 ° C below the isotropic–nematic phase transition on cooling.

High Pressure Studies of Liquid Crystalline Transitions

1983 ◽  
Vol 22 ◽  
Author(s):  
R. Shashidhar
Keyword(s):  
High Pressure ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Maximum Pressure ◽  
Multicritical Point ◽  
Smectic A ◽  
High Pressure Studies ◽  
Molecular Ordering

ABSTRACTSome of the important results emerging from our recent investigations on liquid crystals at high pressure are presented. In particular the following topics will be discussed: i) The relation between Pm, the maximum pressure of smectic stability, and the temperature range of the nematic phase in reentrant nematogenic compounds. ii) Piezothermal studies in the vicinity of the smectic A-nematic transition in 8 OCB. iii) The effect of molecular ordering on the pressure behaviour of the nematic-isotropic transition in reentrant nematic mixtures. iv) The first observation of a multicritical point in a single component liquid crystal.

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).

Reversible microscale assembly of nanoparticles driven by the phase transition of a thermotropic liquid crystal

2017 ◽  
Author(s):  
Niamh Mac Fhionnlaoich ◽  
Stephen Schrettl ◽  
Nicholas B. Tito ◽  
Ye Yang ◽  
Malavika Nair ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Self Assembly ◽  
Nematic Phase ◽  
Hierarchical Control ◽  
Building Blocks ◽  
Model System ◽  
Microscopic Level ◽  
Reversible Process ◽  
Thermotropic Liquid Crystal

The arrangement of nanoscale building blocks into patterns with microscale periodicity is challenging to achieve via self-assembly processes. Here, we report on the phase transition-driven collective assembly of gold nanoparticles in a thermotropic liquid crystal. A temperature-induced transition from the isotropic to the nematic phase leads to the assembly of individual nanometre-sized particles into arrays of micrometre-sized aggregates, whose size and characteristic spacing can be tuned by varying the cooling rate. This fully reversible process offers hierarchical control over structural order on the molecular, nanoscopic, and microscopic level and is an interesting model system for the programmable patterning of nanocomposites with access to micrometre-sized periodicities.

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