X-ray diffraction studies of surface stabilised ferroelectric liquid crystals in both low and high pretilt devices

Abstract

Two commercial ferroelectric liquid crystal mixtures, SCE13* and SCE8*, have been investigated in both low and high pretilt parallel cells using X-ray ‘rocking curve’ techniques. In the smectic A phase the results confirm that a tilted structure is formed if the smectic A layers become thinner on cooling within the phase. In addition the cells with high pretilt surfaces show about 50%of the material has a different layer orientation from that observed in low pretil cells. We propose that this is a region influenced by the SiO surfaces. In the smectic C* phase, only one region is observed in both low and high pretilt cells. However, the layer tilt angle is greater in the high pretilt cells which suggests that the surface is influencing the whole cell structure.