Sodium Chloride (NaCl)
The sodium chloride structure adopts a face-centered cubic lattice with a two-atom basis or as two interpenetrating face centered cubic lattices. The first atom is located at each lattice point, and the second atom is located half way between lattice points along the face-centered cubic unit cell edge.
Views of a single unit cell
The following four structures below are equivalent representations of a single unit cell of NaCl. Each unit cell contains four Na and four Cl atoms. However, visualizing some of the atoms in the neighboring unit cell conveys a better understanding of the crystal structure. In these structures, Cl is green and Na is light purple.
Views of Multiple Unit Cells
The NaCl crystal structure can be generated by periodically reproducing the unit cell. Below are shown a block of 8 (2x2x2) and 27 (3x3x3) unit cells. In this structures below, the crystal is oriented so that the computer monitor is parallel to the (001) plane.
Views of Multiple Unit Cells
Crystal structures of arbitrarily large size can be constructed.
Rotation of Unit Cells
When rotated, the NaCl crystal structure provides different visualizations of the inherent symmetry. For example, in the system on the left, the crystal is oriented so that the computer monitor is parallel to the (011) plane. In the system on the right, the crystal is oriented so that the computer monitor is parallel to the (111) plane.
Crystal Structure Layers (on edge)
Seen in the (011) plane, one clearly observes the layered structure of the crystal.
Crystal Structure Layers (from top)
Seen in the (111) plane, one clearly observes that the triangular arrangement of the atoms in each layers.
Single Layers
In these structures below, only a single slab of atoms of Na (left) or Cl (right) are shown in the (111) plane.
References
Sickafus, K. E. et al. Layered Atom Arrangements in Complex Materials, A Technical Report from Los Alamos National Laboratory, Los Alamos, New Mexico, LA-14205, April 2006. posted: January, 2015.
updated: February, 2015.