Crystal Lattice

Crystal lattice is the periodic and systematic arrangement of atoms that are found in crystals with the exception of amorphous solids and gases. In the simplest of terms, the crystal lattice can be considered as the points of intersection between straight lines in a three-dimensional network. The physical properties of crystals like cleavage, electronic band structure and optical transparency are predominantly governed by the crystal lattice. A unit cell is the smallest component of the crystal lattice and describes the arrangement of atoms in a crystal. The unit cell is characterized by its lattice parameters which consist of the length of the cell edges and the angles between them.

There are seven crystal lattice systems namely monoclinic, triclinic, orthorhombic, rhombohedral, tetragonal, hexagonal and cubic. All these seven crystal lattice have their own variants giving rise to a total of 14 Bravais Lattices. Among these seven lattice systems, the cubic system exhibits the symmetry of a cube is considered to be the simplest and also the most symmetric of all crystal lattices. There are three different types of cubical crystal lattice systems namely Simple Cubic (SC), Body-Centered Cubic (CBC) and the Face Centered Cubic (FCC). As the name indicates, Simple Cubic is the simplest form of the structure. The simple cubic unit cell has one lattice point at each of the eight corners of the cube. The number of lattice points is usually denoted by Z and for a SC, the value of Z is 1. The packing efficiency of a lattice is defined as the ratio of total volume of the cell occupied by the host atom to the volume of the cell. Usually, crystals with higher packing efficiency are preferred because of their favorable properties. This packing efficiency for SC works has been reported to be around 52%.