Structure and Correlations in Smectic B, F and I Phases

Abstract

Abstract The question of which of the known smetic phases exhibitis long range 3 dimensional order is first discussed briefly, The major theme of the paper is the nature of the structure and correlations in SB, SF, and S1 phases. Results are presented about the temperture dependence of the interlayer stacking arrangement and the existence of strong layer undulations in crystalline SB phases and about the existence of a SB phase with very weak positional correlations between layers and short range order within the layers. The raltion between the S1 and SF structures is established for the first time: both consist of uncorrelated layers in which the molecules are tilted relative to the layer normal and have limited positional correlations within layers. Both have 3-d long range bond orientational order of the C-centered monoclinic lattices. They differ in the direction of tilt of the molecules relative to the pseudo-hexagonal packing in the plane normal to the long axes: in SF the tilet is directed towards ...