Order-disorder structures

AbstractAfter introducing the notion of order-disorder (OD) structures, three basic ideas of the theory of OD structures are presented: (1) explanation of the phenomena of polytypism and stacking disorder on the basis of partial symmetries, (2) construction of a symmetry theory for families of crystal structures consisting of layers and (3) definition of a small number of outstanding structures among the infinite number of stacking sequences in a family of OD structures. The relations between OD structures and polytypes and the contents of a database for OD structures are described