Landau theory of the nematic-smectic a tricritical phase transition in a binary mixture of liquid crystals

Date

1995-01-01

Author

Yurtseven, Hasan Hamit

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We have developed in this study a thermodynamic model for the nematic-smectic A (NA) tricritical phase transition of a binary mixture of liquid crystals in analogy with the model for quasi fluid mixtures due to Griffiths. Using the Landau theory with a symmetrical TCP, we have predicted the critical behaviours of the nematic susceptibility, order parameter and the specific heat discontinuity in the vicinity of the TCP.

Subject Keywords

Instrumentation, General Materials Science

URI

https://hdl.handle.net/11511/51593

Journal

PHASE TRANSITIONS

DOI

https://doi.org/10.1080/01411599508200388

Collections

Department of Physics, Article

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A mean-field model for the phase diagram of liquid crystals Tublek, A; Yurtseven, Hasan Hamit; Salihoglu, S (Informa UK Limited, 1998-01-01) In this study we have developed a mean-field model to obtain the phase diagram for a mixture of liquid crystals. Our mean-field model gives the phase diagram of the nematic, smectic A and smectic C phases near the NAC point. We have fitted our model to the experimentally observed data. From this fitting, we conclude that our mean-field model explains correctly the experimentally observed behavior of a mixed liquid crystalline system near the NAC point.
Disorder-induced Raman scattering in ammonium halides Yurtseven, Hasan Hamit (Informa UK Limited, 1995-01-01) The mechanism responsible for the lambda-phase transitions in ammonium halides is investigated within the framework of an extended theory of the disorder-induced Raman scattering. The Raman spectra of ammonium halides have been predicted for both the disordered beta phase (NH4Cl and NH4Br) and the ordered gamma phase (NH4Br). It is postulated that those terms which dominate the dynamic distortions of the lattices and thereby cause the bulk of the disorder-allowed Raman scattering, will also dominate the qua...
A phase diagram near the NAC* point in liquid crystals Salihoglu, S; Tublek, A; Yurtseven, Hasan Hamit (Informa UK Limited, 2000-01-01) Wt study here a mean field model to obtain the phase diagram (concentration versus temperature) near the NAC* point in a binary mixture of liquid crystal. Wr have Fitted our phase line equations to the experimental data for the mixture of SCE9 + SCE10 liquid crystals. We deduce fi om our analysis that there should exist a tricritical point close to the NAC* point on the AC* phase line.
The mean field model with P-2 theta(2) coupling for the smectic A-smectic C* phase transition in liquid crystals Salihoglu, S; Yurtseven, Hasan Hamit; Giz, A; Kayisoglu, D; Konu, A (Informa UK Limited, 1998-01-01) Using mean field theory with a P(2)theta (2) coupling term in the free energy expansion, we calculate the polarization as a function of temperature for the smectic A-smectic C* phase transition in a liquid crystalline material. Our calculated polarization values are in good agreement with the experimental data.
Ultrasonic frequencies correlated with the volume changes of the q[1(1)over-bar-0] mode for the first-order phase transition in NH4Cl Yurtseven, Hasan Hamit (Informa UK Limited, 2000-01-01) We correlate here by means of gamma-Gruneisen relations the volume changes with the ultrasonic frequencies of the q[1 (1) over bar 0] mode of NH4Cl for the first-order phase transition in this crystal. The ultrasonic frequencies were calculated by a method, which we have developed, using the length-change data from the literature at pressures of 0, 0.2, 0.3 and 0.6 kbar in the first-order phase region of NH4Cl.

Citation Formats

H. H. Yurtseven, “Landau theory of the nematic-smectic a tricritical phase transition in a binary mixture of liquid crystals,” PHASE TRANSITIONS, pp. 75–86, 1995, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/51593.