Acta Crystallographica Section B

Structural Science

Volume 56, Part 5 (October 2000)

research papers

Acta Cryst. (2000). B56, 750-765 [ doi:10.1107/S0108768100006480 ]

Architecture of crystal structures from square planes

J. Hauck and K. Mika

Abstract: The crystal structures of ordered b.c.c. (body-centered cubic), f.c.c. (face-centered cubic) or primitive cubic alloys and related NaCl, ZnS or CaF derivative structures are characterized by the self-coordination numbers , of the A atoms with A atoms. Structures with identical and values for all A atoms are at the corners of and structure maps, and can be analyzed for attractive or repulsive interactions of A atoms. Most observed structures are at the borders of the structure map and can be obtained by 10 different combinations of structural units. The different combination mechanisms explain e.g. the shear structures of CuAu II or $\rm Nb_2O_5$ and the occurrence of vacancies in NaCl-related structures like NbO.

Keywords: Ising model; Structure map; Body- and face-centered cubic ordered alloys; Structural units.