On the structure of the biaxial and uniaxial smectic-B-type phases of 14S5, and the apparently second-order phase transition between them

The biaxial smectic-B-type phase of 4-n-pentylbenzenethio-4′-n-tetradecyloxybenzoate (1̄4̄S5) has been studied along with its uniaxial smectic-l B phase. The results are interpreted in terms of identical layer structures in both phases (with the molecules tilted with respect to the layer normal) but with different kinds of disorder (within the layers and between the layers). The transition between the two phases appears to be second order.