Alignment of nematic liquid crystals on domains of TGS

The domain structure of a TGS crystal can be seen under a polarizing microscope on a cleaved crystal surface covered with the nematic MBBA crystal. The domains with the minus end of Ps at the surface appear as dark areas at the extinction of the TGS sample (which corresponds to homeotropic alignment of liquid crystal molecules), in contrast with the antiparallel ones, which are bright (due to the parallel orientation of molecules). For observation of the domain structure close to the phase transition, MBBA + EBBA mixture is to be used. The electric field can be applied on the TGS sample and slow domain switching directly observed.