Five Main Cubic Structures

1. Simple cubic crystal

Each corner of the cubic lattice is occupied by an atom, which is shared by eight neighboring unit cells. It should be noted that only 1/8 of each corner atom is actually inside the cell (Fig. 2(a) and 2(b)).

2. Body-centered cubic crystal

In bcc crystal in addition to the corner atoms, an atom is also located at the center of the cube (Fig. 2(c)).

3. Face-centered cubic (fcc) crystal

It contains one atom at each of the six cubic faces in addition to the eight corner atoms. Note however that only one-half of each atom actually lies inside the fcc unit cell (Fig. 2(d)).

Fig. 2 Simple three-dimensional unit cells (a) Simple cubic unit cell. (b) Pedantically correct simple cubic unit cell including only the fractional portion of each corner atom actually within the cell cube. (c) Body centered cubic unit cell. (d) Face centered cubic unit cell.[1]

4. Diamond structure

A diamond unit consists of two interpenetrating fcc sublattices with one displaced from the other by one-quarter of the distance along a diagonal of the cube. Both Silicon and Germanium exhibit this structure. The corner and face atoms of the unit cell can be viewed as belonging to one fcc lattice, while the atoms totally contained within the cell belong to the second fcc lattice. The second lattice is displaced one-quarter of a body diagonal along a body diagonal direction relative to the first fcc lattice (Fig. 3(a)).

5. Zinc blende structure

It is formed when the Gallium atoms are placed on one lattice and Arsenic atoms on the other fcc lattice in a diamond structure, example is GaAs(Fig. 3(b)).

Fig. 3 (a) Diamond lattice unit cell. (b) Zincblende lattice unit cell. (c) Diamond lattice emphasizing the four-nearest neighbor bonding within the structure. [1]