Dielectric Relaxation Behavior and Thickness Dependent Phase Transition of a Ferroelectric Liquid Crystal

2004 ◽  
Vol 43 (7A) ◽  
pp. 4286-4289 ◽  
Author(s):  
Shyamal Kumar Kundu ◽  
K. Suzuki ◽  
B. K. Chaudhuri
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Relaxation Behavior ◽  
Ferroelectric Liquid Crystal ◽  
Dielectric Relaxation Behavior

Relaxation dynamics of liposomes in an aqueous solution

2015 ◽  
Vol 17 (28) ◽  
pp. 18449-18455 ◽  
Author(s):  
S. K. Kundu ◽  
S. Choe ◽  
K. Sasaki ◽  
R. Kita ◽  
N. Shinyashiki ◽  
...  
Keyword(s):  
Phase Transition ◽  
Aqueous Solution ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Water Mixture ◽  
Liquid Crystal Phase ◽  
Relaxation Dynamics ◽  
Crystal Phase Transition ◽  
Dielectric Relaxation Behavior ◽  
Liquid Crystal Phase Transition

The gel–liquid crystal phase transition has been studied by the temperature and frequency dependent dielectric relaxation behavior of liposomes in an aqueous solution (40 g L−1 DPPC–water mixture).

scholarly journals Study of Dielectric Relaxation Behavior of Liquid Crystal Copolyester Vectra-A by Thermally Stimulated Discharge Current Technique

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Sapna Kalia ◽  
J. K. Sharma ◽  
Vandana Sharma
Keyword(s):  
Activation Energy ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Preexponential Factor ◽  
Relaxation Behavior ◽  
Depolarization Current ◽  
Temperature Range ◽  
Natural Logarithm ◽  
Relaxation Parameters ◽  
Dielectric Relaxation Behavior

The dielectric relaxation behavior of thermotropic liquid crystal copolyester of 73% of p-hydroxy-benzoic acid (HBA) and 27% of 2-hydroxy-6-naphthoic acid (HNA) (Vectra-A) at poling temperature 80°C has been studied using thermally stimulated depolarization current (TSDC) technique in the temperature range from 15°C to 250°C. The TSD currents were obtained for different polarizing fields ranging from 3.8 kV/cm to 19.2 kV/cm. TSD current spectra in the temperature range from 15°C to 250°C show three current maxima around 25°C, 110°C, and 220°C. The maxima around 25°C and 110°C correspond to characteristic dipolar relaxations β and α, respectively. The peak around 220°C is due to space charge effects named as δ-relaxation. The various relaxation parameters like activation energy (U), relaxation strength , preexponential factor , the quantity of charge released (Q) and concentration of trap for β- and α-relaxations at polarizing temperature 80°C for different polarizing fields were evaluated using Bucci-Fieschi fit. The linear variation between activation energy and natural logarithm of preexponential factor indicates the presence of compensation effect for dipolar relaxations of Vectra-A under present poling conditions.

EFFECT OF CELL THICKNESS ON THE DIELECTRIC RELAXATION PROCESSES IN FERROELECTRIC LIQUID CRYSTALS

2008 ◽  
Vol 22 (14) ◽  
pp. 2263-2273 ◽  
Author(s):  
RAJBIR SINGH ◽  
K. K. RAINA
Keyword(s):  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Dielectric Strength ◽  
Relaxation Processes ◽  
Goldstone Mode ◽  
Ferroelectric Liquid Crystal ◽  
Dielectric Relaxation Spectroscopy ◽  
Dielectric Parameters ◽  
Liquid Crystal Material ◽  
Cell Thickness

Dielectric relaxation spectroscopy in the frequency range 50 Hz to 1 MHz has been carried out in a room temperature ferroelectric liquid crystal mixture in the SmC*, SmA and N* phases in cells of different thickness. The relaxation frequency fr, distribution parameter α and dielectric strength δ∊ have been evaluated. Goldstone mode, domain mode and soft mode have been observed. It is found that the cell thickness has a significant effect on the dielectric parameters of the ferroelectric liquid crystal material. The results have been discussed.

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