Journal ArticleDOI
Evidence of Tricritical Behavior at the Nematic Isotropic Transition
TLDR
In this article, the authors derived the value of the ratio (Q*-QNI)/QNI, where Q* is the order parameter at the temperature T* of the absolute stability limit of the isotropic phase and QNI is the condition at the nematic-isotropic transition temperature TNI.Abstract:
Tricritical behavior at the nematic–isotropic phase transition is discussed by means of Landau–de Gennes phenomenological theory. The temperature difference TNI-T* is obtained near the tricritical point. We also obtained the value of the ratio (Q*-QNI)/QNI, where Q* is the order parameter at the temperature T* of the absolute stability limit of the isotropic phase and QNI is the order parameter at the nematic–isotropic transition temperature TNI. As a definite improvement over the earlier attempts utilizing Landau–de Gennes scheme the present work can reproduce low values of (Q*-QNI)/QNI and that of TNI-T* as demanded by experimental observations. The tricritical exponents are calculated from the scaling theory and compared with observed values. Using the Ginzburg criterion, we also determine the critical region of the nematic–isotropic phase transition.read more
Citations
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Journal ArticleDOI
Cotton-Mouton constants and pretransitional phenomena in the isotropic phase of liquid crystals
TL;DR: The Cotton-Mouton constants for three homologous series of liquid crystals were measured in the isotropic phase as mentioned in this paper, and the results were compared with theories on pretransitional phenomena.
Book ChapterDOI
On the Tricritical Point of the Isotropic — Nematic Transition in a Rod-Like Mesogen Hidden in the Negative Pressure Region
TL;DR: In this article, a presentation of experimental results suggesting fluidlike, spinodal and tricritical nature of the isotropic-nematic transition are given. Results presented based on broad-band dielectric spectroscopy and strong electric field induced changes of dielectrics permittivity.
Book ChapterDOI
The Discontinuity of the Isotropic — Masophase Transition in N-Cyanobiphenyls Homologous Series from 4CB to 14CB. Nonlinear Dielectric Effect (NDE) Studies
TL;DR: In this article, the static nonlinear dielectric effect (NDE) in homologous series of 4-cyano-4-n-alkylbiphenyls (nCB, from n=3 to n=14), exhibiting both isotropic - nematic (I-N) and isotropicsmectic A (I -SmA) phase transitions, are presented.
Journal ArticleDOI
Phase equilibria in solutions of platelike particles: systems with steric and dispersive interactions between the platelets.
TL;DR: Numerical calculations show that besides the isotropic- nematic biphasic coexistence range, inclusion of attractive forces resulted in the appearance of nematic-nematic coexistence in both, disks and rods, solutions.
References
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Journal ArticleDOI
Nematic-isotropic phase transition: An extended mean field theory.
TL;DR: This work shows that not only does the presence of density change at the N-I transition argue for the necessary presence of the density-dependent, isotropic component of the intermolecular interaction in the nematic Hamiltonian, but the incorporation of that extra part also materially affects the character of the N -I transition.
Journal ArticleDOI
Critical region of the nematic-isotropic phase transition in the epsilon expansion.
Journal ArticleDOI
Isotropic-nematic transition in an external field
TL;DR: In this article, the effects of an external field on the isotropic-nematic transition in liquid-crystalline substances were studied using the "orientationally averaged pair correlations" approximation.
Journal ArticleDOI
On the Pretransitional Effects in Nematogens
TL;DR: In this article, the experimentally observed strong pretransitional effects in nematogens can be described in terms of a mean field theory if the free energy expansion is not truncated at the quadratic term.