Laboratory: Crystal Structures
Materials Laboratory I
Last updated: 8/25/2010
Table 2: Common Structures For Metals
Atoms per unit cell
1+8x1/8 = 2
-Fe, V, Cr, Mo, Ta, W
6x1/2+8x1/8 = 4
-Fe, Al, Ni, Cu, Ag, Th, Au,
Pb, Ir, Pt, Rh
1+4x1/6+4x1/12 = 2
-Ti, Zn, Zr, Cd, La,
Tl, Re, Os, Am, Ru, Hf
The common and internationally accepted method for crystal identification involves a
description of the symmetry elements contained in the structure along with the unique
locations of atoms within the structure.
Understanding and working with this method is a
semester long course in itself.
It is beyond the scope of this course; however, I want you
to be aware of the designation.
The combined symmetry elements are called space
groups, and the unique atomic positions are called Wyckoff positions.
In this class we will use an easier identification method that will uniquely identify each
structure; however, this method will not describe all of the symmetry contained in the
The concepts of lattice and basis descriptions seem challenging at first, but
with some practice, it can become routine.
Our method will use the Pearson symbol for