Eur. Phys. J. E 7, 5-11 (2002)
DOI: 10.1140/epje/i200101038
Novel twist grain boundary smectic-C phases
M. Brunet1, L. Navailles1 and N.A. Clark21 GDPC - UMR 5581, Université Montpellier II, F34095 Montpellier Cedex 05, France
2 Department of Physics, Ferroelectric Liquid Crystal Materials Research Center, University of Colorado, Boulder Boulder, CO, USA 80309
navailles@crpp.u-bordeaux.fr
(Received 15 March 2001)
Abstract
Several new kinds of smectic-C twist grain boundary phases (TGBC) have been
observed during the last few years. These pure compounds or mixtures exhibit
unusual textures with polygonal lattices (square or hexagonal grids) in the
plane normal to the TGB helix. The structure of these new phases seems to be
complex and different from reported and predicted TGBC phases. In this
article, we review the main results obtained on these different new phases,
and we propose new TGBC structures based on the well-known splayed
polarization -twisted director structures adopted by chiral smectic-C's in
planar aligned (bookshelf) cells. The observed square or hexagonal lattices
are made of superimposed pairs of unwinding lines due to the suppression of
the helix within smectic-C blocks by the grain boundaries (unwinding walls).
A lattice-free TGBC occurs if the helix within smectic-C blocks is
suppressed completely.
61.30.-v - Liquid crystals.
61.30.Jf - Defects in liquid crystals.
61.30.Eb - Experimental determinations of smectic, nematic, cholesteric, and other structures.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002
