Layer Structure of Antiferroelectric Liquid Crystal MHPOBC Studied by X-Ray Diffraction

The layer structure of the antiferroelectric liquid crystal MHPOBC was studied by X-ray measurements. We observed a thermal hysteresis in the layer structure; i.e., a chevron structure was formed in the cooling process, and a bookshelf structure in the heating process. It was found that the layer spacing decreases discontinuously at the Sm C * -Sm C A * transition point for an enantiomeric mixture in the cooling process. The result is discussed on the basis of a phenomenological theory.