X-ray diffraction (XRD) is one of the most important non-destructive tools to
analyse all kinds of matter - ranging from fluids, to powders and crystals. From
research to production and engineering, XRD is an indispensible method for
structural materials characterization and quality control which makes use of the
Debye-Scherrer method. This technique uses X-ray (or neutron) diffraction on
powder or microcrystalline samples, where ideally every possible crystalline
orientation is represented equally. The resulting orientational averaging causes
the three dimensional reciprocal space that is studied in single crystal diffraction
to be projected onto a single dimension. One describes the three dimensional
space with reciprocal axes x*,y* and z* or alternatively in spherical coordinates q,
φ*,
χ*. The Debye-Scherrer method averages over
φ* and
χ* and only q remains as
an important measurable quantity. To eliminate effects of texturing and to achieve
true randomness one rotates the sample orientation. In the socalled diffractogram
the diffracted intensity is shown as function either of the scattering angle 2
θ or as
a function of the scattering vector q which makes it independent of the used X-ray
wavelength. The diffractogram is like a unique “fingerprint” of materials.
This method gives laboratories the ability to quickly analyze unknown materials
and characterize them in such fields as metallurgy, mineralogy, forensic science,
archeology and the biological and pharmazeutical sciences. Identification is
performed by comparison of the diffractogram to known standards or to
international databases.