Study of Phase Transitions in Polymorphic Liquid Crystals

1998 ◽  
Vol 12 (02) ◽  
pp. 213-224 ◽  
Author(s):  
A. Nesrullajev ◽  
S. Salihoğlu ◽  
H. Yurtseven
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Liquid Crystals ◽  
Experimental Method ◽  
Wide Temperature Range ◽  
Field Model ◽  
Mean Field ◽  
High Accuracy ◽  
Mean Field Model ◽  
Phase Transition Temperatures

This work presents our investigations of mezomorphic properties of two polymorphic liquid crystals, namely, 4-nonyloxy-4-butoxyphenyl benzoate and N-(-4-heptyloxybenzylidene-4-butylaniline) in a wide temperature range, particularly, in the phase transition regions. By means of an original experimental method, the heterophase regions and also the phase transition temperatures have been determined for these materials with high accuracy. These phase transition intervals have been analyzed using a mean field model.

The mean field model withP2θ2coupling for the smectic A-smectic C* phase transition in liquid crystals

1998 ◽  
Vol 66 (1-4) ◽  
pp. 259-270 ◽  
Author(s):  
S. SalihoĞLu ◽  
H. Yurtseven ◽  
A. Giz ◽  
D. Kayişoğlu ◽  
A. Konu
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Field Model ◽  
Mean Field ◽  
Mean Field Model ◽  
Smectic A ◽  
Smectic C ◽  
The Mean

TILT ANGLE AND THE TEMPERATURE SHIFTS CALCULATED AS A FUNCTION OF CONCENTRATION FOR THE AC* PHASE TRANSITION IN A BINARY MIXTURE OF LIQUID CRYSTALS

2011 ◽  
Vol 25 (13) ◽  
pp. 1791-1806 ◽  
Author(s):  
H. YURTSEVEN ◽  
M. KURT
Keyword(s):  
Phase Transition ◽  
Free Energy ◽  
Liquid Crystals ◽  
Binary Mixture ◽  
Tilt Angle ◽  
Field Model ◽  
Mean Field ◽  
Temperature Shift ◽  
Mean Field Model ◽  
Mean Field Models

We study here the tilt angle and the temperature shifts as a function of concentration for the AC* phase transition in a binary mixture, using our mean field model with the biquadratic P2θ2 coupling — and also with the bilinear Pθ and P2θ2 couplings. By expanding the free energy in terms of the tilt angle and polarization, the tilt angle and the temperature shift are evaluated by using the coefficients given in the free energy expansion. By employing a concentration-dependent coefficient, the tilt angle and the temperature shift are calculated as a function of concentration of 10.O.4 for the SmAC* transition in a binary mixture of C7 and 10.O.4. Our calculated values of the tilt angle and the temperature shifts decrease as the concentration of 10.O.4 increases, as confirmed experimentally for the AC* transition in this binary mixture. This indicates that our mean field models studied here are satisfactory to explain the observed behavior of the AC* transition of the binary mixture of C7 and 10.O.4.

scholarly journals Topological signature of first-order phase transitions in a mean-field model

2003 ◽  
Vol 62 (6) ◽  
pp. 775-781 ◽  
Author(s):  
L Angelani ◽  
L Casetti ◽  
M Pettini ◽  
G Ruocco ◽  
F Zamponi
Keyword(s):  
Phase Transitions ◽  
Field Model ◽  
Mean Field ◽  
Mean Field Model ◽  
First Order ◽  
First Order Phase

A Phase Diagram for the Ice VI–VII–VIII Transitions

1998 ◽  
Vol 12 (08) ◽  
pp. 271-279 ◽  
Author(s):  
H. Yurtseven ◽  
S. Salihoğlu
Keyword(s):  
Phase Diagram ◽  
Phase Transitions ◽  
Field Model ◽  
Mean Field ◽  
Calculated Phase Diagram ◽  
Mean Field Model ◽  
Phase Line ◽  
Calculated Phase ◽  
The Mean ◽  
T Phase

In this study we obtain the P–T phase diagram for the ice VI–VII–VIII phase transitions by means of the mean field model developed here. We have fitted the experimentally measured P–T data to our phase line equations. Our calculated phase diagram describes adequately the observed behavior of the ice VI–VII–VIII phase transitions.

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