STRUCTURE AND DEFECTS IN DISCOTIC CRYSTALS AND LIQUID-CRYSTALS AS REVEALED BY ELECTRON-DIFFRACTION AND HIGH-RESOLUTION ELECTRON-MICROSCOPY

Both monomeric and polymeric discotic molecules in the crystalline and liquid crystalline phases were investigated by electron diffraction and high-resolution electron microscopy. Analysis of the diffraction patterns indicated the relationship between the orthorhombic, the hexagonal, and the layer-line electron diffraction patterns. The high-resolution images from crystals and liquid crystals showed that the defects which occurred most frequently in the crystals were grain boundaries. These were not observed in liquid crystals. Instead, slight deviations of the molecules from perfect lattice positions disturbed the short-range order while retaining quasi long-range order. Methods are proposed in order to characterize these deviations.