ABSTRACT
Many techniques of analytical chemistry readily identify and determine the quantity of elemental constituents present but do not distinguish the chemical forms of elements present as various compounds in a mixture. X-Ray diffraction (XRD), however, can provide this information for crystalline materials. A species must be crystalline to be analyzed by X-ray diffraction. Therefore, XRD is usually applicable to only solid materials. Although limited to the identification of crystalline materials, the XRD method permits identification of chemical species at relatively low concentrations and is nondestructive. In a film camera, photographic film which is darkened upon X-ray exposure is orientated in such a way around the specimen that it intercepts the cones of diffracted X-rays. The Miller indices identifying various planes are numerical descriptions of the planes that can be used in crystallographic computations. Each set of planes has a constant interplanar spacing as seen in one view of an arrangement of atoms.
