X-ray studies of the phases and phase transitions of liquid crystals
  This is a short review of recent x-ray diffraction studies of the phases and phase transitions of thermotropic liquid crystals. The areas covered are twist-grain-boundary phases, antiferroelectric phases studied with resonant x-ray diffraction, and smectic phases within gel structures. In all areas x-ray diffraction has played a key role. Nonetheless open questions remain: the nature of the smectic-C variant of the twist-grain-boundary phase, the origin of antiferroelectric phases, and whether novel Bragg glass states exist for smectic-A gel samples. 
P.S.Clegg