Browsing by Author "Kilit, E."

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Analysis of the Specific Heat of P-Azoxyanisole (Paa) Near the Phase Transitions
(Taylor & Francis Ltd, 2010) Kilit, E.; Yurtseven, H.
The analysis of the experimental data for the specific heat Cp at various temperatures is given here near the nematic-isotropic liquid (TNI = 133.9 degrees C) and the solid-nematic (TSN = 117.6 degrees C) transitions in p-azoxyanisole (PAA). The analysis of the specific heat Cp is performed according to a simple power-law formula and a renormalisation-group expression. The values of the critical exponent are extracted above and below the transition temperatures of TNI and TSN for this liquid crystalline material. Our exponent values are compared with the predictions of a three-dimensional Ising model and XY model for liquid crystals. Using the specific heat Cp, the temperature dependence of the enthalpy H and the entropy S is calculated in the nematic phase (T TSN) of p-azoxyanisole.
Critical Behavior of the Dielectric Susceptibility for the Ferroelectric Liquid A7
(Springer, 2011) Yurtseven, H.; Kilit, E.
The temperature dependence of the dielectric susceptibility is studied here for the smectic A-isotropic liquid transition of the ferroelectric A7. From the analysis of the experimental data for the dielectric constant, the critical behavior of the dielectric susceptibility is described close to the smectic A-isotropic liquid transition in this liquid crystal.
A First-Order Transition of the Smectic A-Smectic C* in Ferroelectric Liquid Crystals
(Taylor & Francis Ltd, 2012) Kilit, E.; Yurtseven, H.
The static dielectric constant is calculated as a function of temperature using a mean field model close to the smectic A-smectic C* transition for the ferroelectric liquid crystal 4-(3-methyl-2-chlorobutanoyloxy)-4'-heptyloxybiphenyl (A7). This calculation of the dielectric constant is performed for the pure optically active compound (T-c = 73.4 degrees C) and the temperature range is determined for a first-order smectic A-smectic C* transition from the mean field model. Our predicted values describe adequately the observed behaviour of the dielectric constant close to the smectic A-smectic C* transition and also the temperature range in the smectic A phase of A7.
Temperature Dependence of the Dielectric Constant Calculated Using a Mean Field Model Close To the Smectic a - Isotropic Liquid Transition
(intech Europe, 2011) Yurtseven, H.; Kilit, E.
Vibrational Frequencies Studied as a Function of Pressure in Phase Ii of Solid Benzene
(Elsevier Science Bv, 2011) Yurtseven, H.; Rasitoglu, B.; Kilit, E.
The pressure dependence of the vibrational frequencies of six Raman modes is analyzed in phase II of solid benzene. The frequency shifts 1/nu(partial derivative nu/partial derivative P)(T) of those Raman modes are deduced from this analysis and they are related to the isothermal compressibility kappa(T)= -(1/V)(partial derivative V/partial derivative P)(T) through a constant isothermal mode Gruneisen parameter gamma(T) in phase II of solid benzene. The kappa(T) values predicted here are compared with the kappa(T) obtained from the volumetric measurements in this phase. It is shown here that the isothermal compressibility can be predicted from the vibrational frequencies measured in phase II of solid benzene. (C) 2011 Elsevier B.V. All rights reserved.