ABSTRACT
The crystallites in polycrystalline structures are randomly oriented. The small crystallites are known as grains and the boundaries separating them as grain boundaries. The crystal structure is always described in terms of atoms rather than point. Hence, to achieve a crystal structure, an atom or a group of atoms must be placed on each lattice point in a regular fashion. A symmetry operation is an operation that can be performed either physically or imaginatively that results in no change in the appearance of an object, that is, a crystal remains invariant under a symmetry operation. The orientation of a surface or a crystal plane may be defined by considering how the plane intersects the main crystallographic axes of the solid. The lattice vectors of a simple cubic (SC) crystals are orthogonal and of equal length. The unit cell of an SC structure is a cube with an atom at each corner and the same as the primitive cell.
