Architecture of crystal structures from square planes

The crystal structures of ordered b.c.c. (body-centered cubic), f.c.c. (fac e-centered cubic) or primitive cubic alloys A(x)B(y) and related NaCl, ZnS or CaF2 derivative structures are characterized by the self-coordination nu mbers T-1, T-2 of the A atoms with A atoms. Structures with identical T-1 a nd T-2 values for all A atoms are at the corners of T-1 and T-2 structure m aps, and can be analyzed for attractive or repulsive interactions of A atom s. Most observed structures are at the borders of the structure map and can be obtained by similar to 10 different combinations of structural units. T he different combination mechanisms explain e.g. the shear structures of Cu Au II or Nb2O5 and the occurrence of vacancies in NaCl-related structures l ike NbO.