INTERLAYER CORRELATIONS IN SMECTIC-B PHASES

X-ray diffraction results are presented on very well aligned samples of several smectic B phases which show the existnce of several kinds of interlayer correlations. The hexagonal closepacked layers may be stacked with ordered ABA. . . or ABCA. . . arrangements (where A, B and C denote the relative position of the layers), with a random array of ABC-type planes, or with almost no correlation between layers. No clear examples of the simple monolayer packing AA. . . have been found.