WEAKLY FIRST-ORDER OR NEARLY 2ND-ORDER PHASE-TRANSITIONS IN AMMONIUM HALIDES

Date

1994-01-01

Author

Yurtseven, Hasan Hamit

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This work is mainly concerned with the application to the ammonium chloride system of the model that was developed by Yurtseven (1993).

Subject Keywords

Instrumentation, General Materials Science

URI

https://hdl.handle.net/11511/57734

Journal

PHASE TRANSITIONS

DOI

https://doi.org/10.1080/01411599408200337

Collections

Department of Physics, Article

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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...
WEAKLY FIRST-ORDER OR NEARLY 2ND-ORDER PHASE-TRANSITIONS Yurtseven, Hasan Hamit (Informa UK Limited, 1994-01-01) In this study we have developed a model which is mainly for a spin system (Ising model) superimposed on a system of lattice vibrations (Einstein and/or Debye model). Under this model we have derived the thermodynamic functions and predicted their critical behaviour near T-c.
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.
Landau theory of the nematic-smectic a tricritical phase transition in a binary mixture of liquid crystals Yurtseven, Hasan Hamit (Informa UK Limited, 1995-01-01) 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.
A phase diagram for ammonium halides Yurtseven, Hasan Hamit; Tublek, A (Informa UK Limited, 1995-01-01) In this study we have developed a mean field model to obtain the phase diagrams for NH4Cl and NH4Br. The phase diagrams obtained from our macroscopic theory are in good agreement with those obtained experimentally.

Citation Formats

H. H. Yurtseven, “WEAKLY FIRST-ORDER OR NEARLY 2ND-ORDER PHASE-TRANSITIONS IN AMMONIUM HALIDES,” PHASE TRANSITIONS, pp. 69–75, 1994, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/57734.