Paracrystalline Lattices in Mesophases and Real Structures

Abstract

The strucature of liquid crystals to some extent can be understood as mesophases (C. Hermann). Unfortunately, by the statistical group theory only a small number of partially amorphous, partially crystalline structures (so-called a,z-structures) can be described. It is shown that the concept of paracrystals not only contains more of such “a,z-structures” but a large variety of more or less distored lattices, which are not of the a,z-type. This is illustrated by Rraunhofer patterns with a He-Ne-Laser of two-dimensional models of paracrystallilne point structrues. Some further examples of solids with paracrystalline lattices on the atomic and colloidal scale are given.