X-Ray Diffraction

X-Ray diffraction (XRD) is a scientific technique that allows the investigator to determine which chemical compounds and the relative amounts of those compounds that are present in the sample. Each element, i.e. iron (Fe), sulfur (S), and copper (Cu), etc., and each chemical compound, i.e., salt (NaCl), iron oxide (Fe₂O₃), iron sulfide (FeS), etc. has a unique structure. That is, the atoms in the element or compound are arranged in space on a  repeatable three dimensional structure that extends for large atomic distances ( compared to the size of the atom). XRD is used to determine this unique spatial arrangement.