X-RAY DIFFRACTION: DETERMINATION OF CRYSTAL STRUCTURES

Diffraction occurs when a wave encounters a series of regularly spaced obstacles that (1) are capable of scattering the wave, and (2) have spacings that are comparable in magnitude to the

wavelength. Furthermore, diffraction is a consequence of specific phase relationships established

between two or more waves that have been scattered by the obstacles.

The magnitude of the distance between two adjacent and parallel planes of atoms (i.e., the interplanar spacing ) is  a function of the Miller indices  (h, k,  and  l) as well as the lattice parameter(s). For example, for crystal structures that  have cubic symmetry