Structures of binary inorganic A_xB_y compounds with A and B on two Wyckoff positions are characterized by the self-coordination numbers T_i, i = 1 – 3, of A and B atoms. The T₁ = 0 – 12 values of 122 structure types can be correlated with different topologies, A–A interactions and densities. High T₁ values like T₁ = 12 are obtained for fcc or hcp sphere packing with maximum density of A atoms and interstitial B atoms. Hexagonal or tetragonal layered compounds are recognized by the T_i values 6 6 6 or 4 4 4. The T₁ = 2 values are found for chains, T₁= 1 for ordered molecules like N₂ or Br₂. The A and B atoms of few compounds like NaCl or CsCl form a pc or bcc sphere packing. The T₁ = 0 values of Na or Cs atoms indicate repulsive Na–Na or Cs–Cs interactions. Distorted structures of a structure type are recognized, if atoms with slightly different A–A or B–B distances are included in the proper coordination shells.

---

The full text of this paper in pdf-Format:

If you have come directly to this page, click this symbol to go to the CRT homepage.