The radius of an atom is . If the crystal lattice is face-centred cubic, what is the packing efficiency of the lattice? (Assume that atoms are perfect spheres)
For a face-centred cubic lattice, the packing efficiency is given by the expression: where n is the number of atoms per unit cell, r is the radius of the atom, and V is the volume of the unit cell. Substituting the given values, we get:
where a is the edge length of the unit cell. Simplifying this expression gives us a packing efficiency of approximately