Realignment of a smectic-A phase with applied electric field

The realignment of a smectic-A phase contained in a conventional display device (with a mesophase layer similar to 10 mum thick) in response to an applied electric field has been studied using polarizing microscopy and x-ray diffraction. The initial state of the mesophase was a highly aligned focal conic texture. The applied field created a striated texture with parallel (but not equally spaced) disclination lines which appeared to be created in pairs. The lines seem to grow from disclination "eyes" in the original texture, linking them first:ln pairs, and then in long chains, as the field is increased. We suggest that the center of each pair of striations corresponds to a disclination wall and that the texture consists of a parallel array of smectic layers arranged in concentric flattened half-cylinders. Previous electro-optic studies of cells of this type have described the striated, field-on texture but appear to have overlooked the role of the defects in the original texture as growth points for the striations. However, there are structural similarities with two related studies where the field-induced disturbance of the mesophase starts with the production of toroidal focal conics-similar to those we propose.