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.


Yurtseven, Hasan Hamit (Informa UK Limited, 1994-01-01)
This work is mainly concerned with the application to the ammonium chloride system of the model that was developed by Yurtseven (1993).
T-X-Br phase diagram for the NH4BrxCl1-x system
Tari, O; Yurtseven, Hasan Hamit; Salihoglu, S (Informa UK Limited, 2000-01-01)
In this study using a mean field model we calculate the phase line equations for the beta-delta, beta-gamma and gamma-delta phase transitions in the NH4BrxCl1-x system. We then fit our phase line equations to the experimentally observed T-X-Br phase diagram for this system. Our calculated phase diagram agrees well with the observed one for the NH4BrxCl1-x system.
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.
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...
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.
Citation Formats
H. H. Yurtseven, “WEAKLY FIRST-ORDER OR NEARLY 2ND-ORDER PHASE-TRANSITIONS,” PHASE TRANSITIONS, pp. 59–68, 1994, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/56515.