Critical behaviour of optical birefringence in the vicinity of nematic–isotropic and smectic A–isotropic phase transitions of the eight members of alkyloxy-cyanobiphenyls

2016 ◽  
Vol 43 (9) ◽  
pp. 1268-1275 ◽  
Author(s):  
Malay Kumar Das ◽  
Purna Chandra Barman ◽  
Sudipta Kumar Sarkar
1995 ◽  
Vol 09 (18n19) ◽  
pp. 2247-2283 ◽  
Author(s):  
DANIELE FINOTELLO ◽  
GERMANO S. IANNACCHIONE

We review results of a high resolution systematic study of the specific heat for alkyl-cyanobiphenyl liquid crystals confined to the 0.2µm diameter cylindrical pores Anopore membranes. The nematic director alignment at the pore wall is varied from homeotropic to tangential by pore surface treatment. Several phenomena are uncovered by these studies which probed the weakly first order nematic to isotropic, the continuous smectic-A to nematic and the first order smectic-A to isotropic phase transitions. The specific heat is strongly dependent on the nematic director configuration, and confinement effects are remarkably distinct according to the order of the phase transition. The influence of elastic distortions and surface ordering and disordering effects are evident. Despite considerable departures from bulk behavior with regards to specific heat peaks size, rounding and width, and transition temperature shifts, a bulk-like critical behavior appears to be retained. The formation of smectic translational order within the pores is hindered for those liquid crystals that also possess a nematic phase. The average scalar order parameter temperature dependence is extracted from the specific heat results using a simplified Landau-de Gennes type of model, and is shown to be consistent with nuclear magnetic resonance results.


1995 ◽  
Vol 09 (13) ◽  
pp. 791-799 ◽  
Author(s):  
I. CUCULESCU ◽  
A. L. ALEXE-IONESCU ◽  
R. BENA ◽  
C. GHIZDEANU ◽  
V. STOIAN ◽  
...  

The transition temperatures from smectic C* to isotropic phase of a liquid crystal have been recorded as a function of an applied electric field. In addition to recent investigations on the phase transitions from smectic C* to smectic A in an electric field, we have found, in our case, a decrease of the transition temperature with the electric field. An explanation has been suggested to this behavior and a formula has been obtained which fits well the experimental points.


1995 ◽  
Vol 19 (5) ◽  
pp. 629-635 ◽  
Author(s):  
P. Göring ◽  
G. Pelzl ◽  
S. Diele ◽  
P. Delavier ◽  
K. Siemensmeyer ◽  
...  

2006 ◽  
Vol 20 (14) ◽  
pp. 821-833 ◽  
Author(s):  
ARIF NESRULLAJEV ◽  
ŞENER OKTIK

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.


2008 ◽  
Vol 41 (6) ◽  
pp. 062002 ◽  
Author(s):  
SeungYeon Jeong ◽  
DongWoo Kim ◽  
KungWon Rhie ◽  
MunPyo Hong ◽  
Satyendra Kumar ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document