Body-centered cubic unit cells have an atom in the
center of the cube as well as one in each corner. The packing efficiency is 68%, and the
coordination number = 8. Atoms touch each other along cube diagonals
within a unit cell. All atoms are
identical.
ex: Cr, W, Fe (a),
Tantalum, Molybdenum
Close-packed directions: length = 4R = sqrt (2a)
Unit cell contains:
6 x 1/2 + 8 x 1/8 = 4 atoms/unit cell
Elements with monoatomic BCC structure
