X-Ray Diffraction

X-ray crystallography is the science of determining the arrangement of atoms within a crystal from the manner in which a beam of X-rays is scattered from the electrons within the crystal. The method produces a three-dimensional picture of the density of electrons within the crystal, from which the mean atomic positions, their chemical bonds, their disorder and sundry other information can be derived. By definition, a crystal is a solid in which a particular arrangement of atoms (its unit cell) is repeated indefinitely along  three principal directions known as the basis (or lattice) vectors, which are not necessarily perpendicular. A wide variety of materials can form crystals — such as salts, metals, minerals, semiconductors, as well as various inorganic, organic and biological molecules — which has made X-ray crystallography fundamental to many scientific fields.
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X-ray scattering techniques are a family of non-destructive analytical techniques which reveal information about the crystallographic structure, chemical composition, and physical properties of materials and thin films. These techniques are based on observing the scattered intensity of an x-ray beam hitting a sample as a function of incident and scattered angle, polarization, and wavelength or energy.
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Noun
1. the scattering of X rays by the atoms of a crystal; the diffraction pattern shows structure of the crystal
(hypernym) diffraction

The scattering of X-rays passed through a mineral sample so as to form a pattern peculiar to the given mineral.

Definition
Powder X-ray Diffraction (XRD) is one of the primary techniques used by mineralogists and solid state chemists to examine the physico-chemical make-up of unknown solids. This data is represented in a collection of single-phase X-ray powder diffraction patterns for the three most intense D values in the form of tables of interplanar spacings (D), relative intensities (I/Io), and mineral name.
The XRD technique takes a sample of the material and places a powdered sample in a holder, then the sample is illuminated with x-rays of a fixed wave-length and the intensity of the reflected radiation is recorded using a goniometer. This data is then analyzed for the reflection angle to calculate the inter-atomic spacing (D value in Angstrom units - 10-8 cm). The intensity(I) is measured to discriminate(using I ratios) the various D spacings and the results are to identify possible matches.

DIFFUSIONE DEI RAGGI X ATTRAVERSO GLI ATOMI DI UN CRISTALLO