Three dimensional close packing from two dimensional square close-packed layers:
- The second layer is placed over the first layer in such a way that the spheres of the upper layer are exactly above those of the first layer.
- In this arrangement of spheres, both the layers are perfectly aligned horizontally as well as vertically.
- Let the first row be ‘A’ type row, and the second row be ‘B’ type row.
- Thus this lattice has AAA.... type pattern.
- The lattice therefore generated is the simple cubic lattice, and its unit cell is the primitive cubic unit cell.