Self-assembled uniaxial and biaxial multilayer structures in chiral smectic liquid crystals frustrated between ferro- and antiferroelectricity.

With a view to obtain a molecular model for the subphases produced by the frustration between ferro- and antiferroelectricity in chiral smectic liquid crystals, we report results on two compounds and observe (i) the staircase character of uniaxial Sm C()(alpha) itself in the bulk and (ii) the multipeaked characteristic reflection bands due to the modulated helical structures just above the Sm C()(A) temperature range. We suggest the emergence of several uniaxial and biaxial subphases. The results show that both types of subphases can be specified by q(T) = [F] / ( [A] + [F] ) in the zero-order approximation; [A] and [F] are the numbers of antiferroelectric and ferroelectric orderings in the unit cell. We consider the basis of both types of subphases, particularly the description of the short-pitch helical structure of Sm C(*)(alpha), in terms of the molecular models so far proposed and emphasize the important role played by the discrete flexoelectric polarization.