Fig. 6. Schematic illustration of atomic arrangements in ordered (left) and disordered (right) ionic materials.

The red circles represent anions, and the different blue and green circles represent unique cation species. When a material that appears structurally disordered over longer length scales is studied at the atomic-scale, the actual atomic configuration and accompanying structural distortions obey Pauling’s rules. The rules are labeled for the length scales over which they are primarily applicable.