A08    Discuss the packing density of the simple cubic, the body-centered cubic, and the face-centered cubic structure, and identify the maximal packing density of these three structures.

Characteristic Properties of Crystalline Structures:

• Long range order
• When exposed to x-rays of a particular wavelength, x-ray spectra are generated

Crystalline Structures

• Cubic
  • Simple cubic
  • Body-centered cubic
  • Face-centered cubic
• Rhombohedral
• Orthorhombic
• Monoclinic
• Triclinic
• Tetragonal
• Hexagonal
  • Simple hexagonal
  • Close-packed hexagonal
• Rhombic

Cubic Structure

Simple cubic structure

The simple cubic structure contains only one atom per cube. The reason is that only 1/8th of each corner atom falls within the cube. The other 7/8th belong to adjacent cubes.

Body centered cubic structure

The body centered cubic structure contains a total of 2 atoms per cube.

Face centered cubic structure

The face centered cubic structure contains a total of 4 atoms per cube. This structure is common in gold alloys used in dentistry.

Rhombohedral

Orthorhombic

Monoclinic

Triclinic

Tetragonal

Hexagonal

Simple hexagonal

Close-packed hexagonal

Rhombic