Crystals and lattices
See also: crystal directions, planes and the zone axis, crystal symmetry.
Crystalline material consists of a regular repetition of a group of atoms in three dimensional space. A crystal lattice is an infinitely repeating array of points in space .
The unit cell of the lattice is the basic repeating unit of the lattice and is characterized by a parallelepiped with cell edge lengths a, b, c and inter axis angles α, β ,γ.
These unit cells can be classified as belonging to one of fourteen Bravais lattices. Each Bravais lattice belongs to one of the seven crystal systems.
The motif is the group of atoms repeated at each lattice point.