Showing papers by "Krzysztof Czupryński published in 2005"
TL;DR: This paper recalls the recent discussions on the glassy dynamics of a "hard-ellipsoid" liquid and the possible relationship between the glass transition, critical phenomena, and isotropic-nematic transition.
Abstract: Linear and nonlinear dielectric measurements of liquid crystalline chiral isopentylcyanobiphenyl $(5*\mathrm{CB})$ and $n$-pentylcyanobiphenyl (5CB), combined with viscosity $\ensuremath{\eta}(T)$ data, are presented. The $5*\mathrm{CB}$ compound glassifies on cooling in the cholesteric phase whereas 5CB crystallizes in the nematic phase. In both compounds the temperature evolution of dielectric relaxation times, the dc conductivity, and the viscosity are well described by the ``critical-like'' description from mode coupling theory (MCT). However, for $5*\mathrm{CB}$ a unique coincidence of the MCT ``critical'' temperature and extrapolated temperature of the hypothetical continuous isotropic-cholesteric $(T*)$ phase transition was found. The temperature dependence of the strong electric-field-induced changes of the dielectric permittivity exhibits a strong anomaly in the direction of negative values on approaching $T*$, not observed up to now. The anomaly is described by the susceptibility-related critical exponent $\ensuremath{\gamma}=1$. The divergence of the ``nonlinear'' dielectric relaxation follows a power dependence described by the exponent $y=1$. This paper recalls the recent discussions on the glassy dynamics of a ``hard-ellipsoid'' liquid and the possible relationship between the glass transition, critical phenomena, and isotropic-nematic transition.
31 citations
TL;DR: In this paper, a new LC material based on chain fluorinated homologous ester series and exhibiting high tilt angles of the synclinic and anticlinic smectic C phases to the layer surface is synthesized.
Abstract: New LC materials based on chain fluorinated homologous ester series and exhibiting high tilt angles of the synclinic and anticlinic smectic C phases to the layer surface are synthesized. Their mixtures in surface-stabilized geometry show an unusually huge change of optical properties after application of an electric field during the transition from the antiferroelectric to the ferroelectric state. In the antiferroelectric state they are optically negative uniaxial liquid crystals with the optic axis perpendicular to the cell plates, while in the ferroelectric state they become optically positive biaxial liquid crystals with optic axis parallel to the glass plates. The results of electrooptical characterization of the mixtures are presented. © 2005 Optical Society of America
2 citations
20 Sep 2005
TL;DR: In this article, the optic and electrooptic properties of recently prepared orthoconic antiferroelectrics have been investigated and the relation between their chemical structure and mesogenic properties, smectic layer structure and helical pitch is discussed.
Abstract: The optic and electrooptic properties of recently prepared orthoconic antiferroelectrics have been revieved. Relation between their chemical structure and mesogenic properties, smectic layer structure and helical pitch is discussed.
1 citations