The Structure of Solids

· Replacing the anion array by layers of coordination tetrahedra and octahedra builds the crystal structure.
· Their arrangement for fcc and hcp structures is shown in an exploded form. In the actual structure all these polyhedra collapse together.
· Cations are now introduced into some or all of the interstitial sites to give the neutral crystal structure.

From: Guy and Hren, "Elements of Physical Metallurgy," Addison Wesley (1974)