FACE CENTERED CUBIC STRUCTURE

Atoms touch each other along face diagonals. All atoms are identical; the face-centered atoms are shaded differently only for ease of viewing.

ex: Al, Cu, Au, Pb, Ni, Pt, Ag

 

 

  

Coordination no = 12

4 atoms/unit cell: 6 face x 1/2 + 8 corners x 1/8

Atomic Packing Factor for a face-centered cubic structure = 0.74

Close-packed directions: length = 4R = sqrt (2a)

Unit cell contains: 6 x 1/2 + 8 x 1/8  = 4 atoms/unit cell