X-ray diffraction (XRD) is a powerful nondestructive technique for characterizing crystalline materials. It provides information on structures, phases, texture, and other structural parameters (i.e., grain size, crystallinity, strain, and crystal defects). In particular, X-ray powder diffraction is crucial in materials science because many materials and minerals are not available in a single-crystal form. In the laboratory, the analyzed material is finely ground, homogenized, and the phase composition is determined through the XRD investigation. Although the technique is called X-ray powder diffraction, any polycrystalline specimen can be studied with a noninvasive approach by using this technique. This is the case of materials of interest in Heritage Science where most of the samples present a polycristalline nature; and the use of XRD provides their phase composition (and in turn the chemical composition) in a quite rapid measurement. XRD is performed by means of a monochromatic X-ray beam that is projected into the sample. The way how the X-ray beam is scattered at specific angles by the atoms arranged in the lattice planes produces interference patterns that can be investigated by the Bragg law. The peak intensities and positions in the angular range exammined by the XRD investigation provide a fingerprint of the phase composition of a given material.
architecture, art, decorative arts, manuscript, mosaics, painting, papyrus, textile
fossil, mineral, shell
ceramic (clay/mud brick/terracotta/earthenware/stoneware/porcelain), glass, stone, metal and metallurgical By-Products, pigment
The mobile XRD scanner consists of a measurement head equipped with an high brilliant monochromatic source (two sources with with Ag or Cu anodes respectively are available) focused with a Montel multilayer optic down to a spot-size in the range of 100 microns and with a divergence of about 7.5 mrad. The primary X-ray source...