100 years of crystallography: new dimensions offered by large scale facilities

Abstract

100 years have passed since the discovery of x-ray diffraction by von Laue, Knipping and Friedrich. The scientific world owes a lot to Rontgen for the discovery of x-rays in 1895 and with the research efforts of W L and W H Bragg in 1912, the concept of Bragg’s law and interpretations given by P P Ewald, saw the birth of the wonderful field of crystallography. Today, the scientific world sees the various tools delivered by this powerful technique as indispensible, whether it concerns the development of advanced high-tech materials or the structural understanding of biological molecules or drug design. Diffraction and associated methods for structure analysis at the atomic scale are developed into powerful fingerprint methods, and have become the backbone of industry for quality inspection on one hand, and on the other hand, stand at the forefront of materials characterization in research laboratory. Beyond these characterization tools available at laboratory level, large scale facilities (LSF) and notably the neutron and synchrotron radiation sources became increasingly important during the last decades. Diffraction with neutron or synchrotron radiation is very complementary, as outlined below: Neutrons have the corresponding wavelengths and energies directly related to interatomic distances and lattice dynamics. Thus, neutron scattering enables simultaneous access to both structure and dynamics of any type of materials. Neutrons also have a magnetic moment allowing direct characterization of the magnetic structure of materials at the microscopic scale. The possibility to easily vary the contrast of a single element using its different isotopes renders the neutron to be an irreplaceable tool in chemistry, solid state physics, biology and soft matter. Then, having no electric charge, neutrons can easily penetrate materials without significant absorption, allowing a nondestructive characterization even on large volume fractions