Selami SalihoGLU

T–P phase diagram of ammonia solid phases I, II and III

In this study, using the mean field theory, we obtain temperature versus pressure phase diagram for the liquid and solid phases I, II, and III of ammonia. We fit our phase line equations to the experimentally observed data. There exists good agreement between the theoretical and experimental phase lines.

Some peculiarities of nematic–isotropic liquid phase transitions in monomorphic and polymorphic mesogens

In this study, the dynamics of the changes of the morphological properties in the nematic mesophase and in the heterophase regions of the phase transitions between the nematic mesophase and the isotropic liquid for the thermotropic mesogens have been investigated. Experimentally, we have obtained the thermal hysteresis for the investigated phase transitions. For the analysis of the phase transition temperatures and the peculiarities of the heterophase regions, the mean field theory has been used.

Calculation of the T-X phase diagram for a mixture of liquid crystals

In this study we calculate the T-X phase diagram for a mixture of liquid crystals. In this calculation we use a mean field theory. We fit our calculated phase line equations to the experimental data from the literature. There is a very good agreement between our calculated and the experimentally observed phase diagram.

Calculation of the free energies for the solid phases of ammonium halides

Using mean field theory, we calculate the free energies of the solid phases of ammonium halides. The temperature and pressure dependences of the free energies are obtained using experimental phase diagrams of the ammonium halides. From these dependences, we calculate numerically the specific heat as a function of temperature for the solid I–liquid, solid II–liquid and solid I–solid II transitions in the ammonium halides, in particular for NH4Cl. The critical behaviour of some other thermodynamic quantities is also predicted from the mean field theory.

P–T phase diagram for NH4F

Abstract In this study we obtain a P–T phase diagram of NH 4 F using the mean-field theory. We fit our calculated phase line equations to the experimental P–T phase diagram. By choosing appropriately the coefficients in the free-energy expansions, our calculated phase diagram agrees well with the experimentally observed phase diagram of NH 4 F.

A temperature-concentration (T-X) phase diagram calculated using the mean field theory for liquid crystals.

Phase-line equations for smectic–hexatic phase transitions in liquid crystals were derived using the Landau phenomenological theory. In particular, second-order transitions for the smectic-A–smectic-C (SmA–SmC) and hexatic-B–hexatic-F (or HexI) transitions were studied and the tricritical points for these transitions were located. The calculated phase-line equations were fitted (using experimental data for various liquid crystals) to construct a generalized T–X phase diagram. It was shown that the T–X phase diagram calculated from the free energy adequately describes the observed behavior of liquid crystals during smectic–hexatic transitions.

A phase diagram near the NAC point in liquid crystals

In this study using a mean field model we obtain the phase line equations for the NA, NC and AC transitions near the NAC point in a mixture of liquid crystals. We then fit these phase line equations to the experimental data. This fitting shows that our theoretical phase diagram predicts the correct experimental behaviour of the phase diagram in a mixture of liquid crystals.