Common cubic structures
The cubic crystal system is one of the most common (and by far the simplest) class of crystals. As the name itself suggests, all crystal structures of this system have a cube-shaped unit cell with edge length given by the lattice parameter ‘a’.
The three main common representatives are:
- the simple cubic structure (sc) (also known as primitive cubic)
- the body-centred cubic structure (bcc)
- the face-centred cubic structure(fcc)
The simple cubic structure (sc)
In the simple cubic structure there is only one lattice point at each corner of the cube-shaped unit cell. They mark the position of either a single atom, or the same group of atoms, known as the motif, which is repeated across the lattice. The simple cubic structure with only one atom per lattice point is relatively rare in nature, as it is fairly unstable because of its low packing efficiency and low number of nearest neighbour around each atom. Polonium (Po) is reported to crystallize in the simple cubic structure.
Make your own 3D paper model of a simple cubic structure with our cutting instructions, and explore its nature.
The body-centred cubic structure (bcc)
The body-centred cubic structure is based on the simple cubic structure, but has an additional lattice point at the very centre of the cube. The packing efficiency and the nearest neighbour interaction are slightly higher than for the simple structure, so it is more common in nature. Prominent metallic solids with this structure are Irom (Fe), Chromium (Cr), and Tungsten (W).
Make your own 3D paper model of a body centered cubic structure with our cutting instructions, and explore its nature.
The face-centred cubic structure (fcc)
Another structure based on the simple cubic structure is face-centred cubic. In this crystal structure there are the eight lattice points at each corner, as in the simple cubic, but there are additional lattice point at the centre of each face of the cube. This structure is very common for metallic elements as it maximises the packing efficiency and has the highest number of nearest neighbours, increasing its stability. This is why the fcc structure is sometimes also called the cubic close-packed structure.
Make your own 3D paper model of a face centered cubic structure with our cutting instructions, and explore its nature.