Showing papers by "Samo Kralj published in 1996"
TL;DR: A deuterium NMR study of the pentylcyanobiphenyl liquid crystal confined to a controlled pore glass matrix with pore radii of 12, 150, and 200 nm was performed, finding the onset of nematic ordering is bulklike in the 150- and 200-nm samples.
Abstract: A deuterium NMR study of the pentylcyanobiphenyl liquid crystal confined to a controlled pore glass matrix with pore radii of 12, 150, and 200 nm was performed. In the 12-nm sample the nematic to isotropic transition is gradual. In the nematic phase the absorption spectrum is substantially narrowed due to translational diffusion of nematic molecules, which is effective because of the inhomogeneous nematic ordering. The external magnetic field influence is negligible. The onset of nematic ordering is bulklike in the 150- and 200-nm samples. There, the absorption spectrum is strongly affected by the external magnetic field. The 150-nm sample exhibits memory effects depending on history of temperature and external field changes.
43 citations
TL;DR: It is demonstrated that smectic elasticity can cause strong deviations from the preferred surface anchoring direction and the chevron and bookshelf structures are found to be the most stable in the weak anchoring regime.
Abstract: Model structures of a smectic-A liquid crystal confined to a long cylindrical cavity enforcing homeotropic surface anchoring are studied theoretically. The structures are obtained numerically through minimization of the Landau--de Gennes type free energy. We limit our discussion to cylinders with submicrometer radia. Five qualitatively different smectic-A configurations are proposed: the smectic-planar-radial, smectic-escaped-radial, chevron, bookshelf, and hybrid structures. Our analysis suggests that in the strong anchoring regime the smectic--escaped-radial structure is the most stable. For this structure relatively large temperature shifts of the nematic--smectic-A phase transition are expected. In the weak anchoring regime the chevron and bookshelf structures are found to be the most stable. We demonstrate that smectic elasticity can cause strong deviations from the preferred surface anchoring direction. \textcopyright{} 1996 The American Physical Society.
25 citations