The specific heat Cp has been showed at various temperatures in the literature, which shows a
sharp increase labeled as the lambda-transition at the critical temperature. This transition has been
observed previously among the phases of solid-nematic-isotropic liquid in p-azoxyanisole
(PAA) and anisaldazine (AAD), and among the phases of solid-smectic-cholesteric-isotropic
liquid in cholesteryl myristate (CM). In this thesis work, we analyze the experimental data for
the temperature dependence of Cp and the thermal expansion alpha_p and also pressure dependence
of alpha_p by a power-law formula. From the analysis of pressure dependence of alpha_p, we calculate
the temperature dependencies of specific heat Cp and of the isothermal compressibility kappa_T for
the phase transitions considered in PAA, AAD and CM. Our calculations for the temperature
dependence of the p and kappa_T can be compared with the experimental data when available in
the literature.
Polarization, tilt angle and the dielectric constant have been reported in the literature at various
temperatures close to the solid-smectic C*-smectic A-isotropic liquid transition in the
ferroelectric liquid crystals of A7 and C7. The mean field model with the free energy expanded in terms of the order parameters (polarization and tilt angle) has been reported in the
literature previously. In this thesis work, we apply the mean field model first time by fitting
the expressions derived for the temperature dependence of the polarization, tilt angle and
the dielectric constant to the experimental data for A7 and C7 from the literature. Since the
mean field model studied here describes adequately the observed behaviour of A7 and C7, the
expressions for the temperature dependence of the polarization, tilt angle and the dielectric
constant which we derive, can also be applied to some other ferroelectric liquid crystals to
explain their observed behaviour.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612963/index.pdf |
| Date | 01 February 2011 |
| Creators | Kilit, Emel |
| Contributors | Yurtseven, Hamit |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for METU campus |
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