Smectic-A*-smectic-C* transition in a ferroelectric liquid crystal withoutsmectic layer shrinkage

The smectic layer spacing of a nonfluorinated ferroelectric liquid crystal (FLC) compound with almost no shrinkage and only minor tendency to form zig zag defects was characterized by small angle x-ray diffraction. The materia l lacks a nematic phase. The smectic-A*-smectic-C* phase transition was stu died by measuring the thermal and electric held response of the optical til t and the electric polarization. These properties are described very well b y a Landau expansion even without introduction of a higher-order Theta(6) t erm. This result suggests a pure second-order phase transition far from tri criticality and differs considerably from the typical behavior of the A*-C* transition in most FLC materials. [S1063-651X(99)01907-8].