100 years of crystallography: new dimensions offered by large scale facilities
Résumé
100 years have passed since the discovery of x-ray diffraction by von Laue, Knipping and
Friedrich.
The scientific world owes a lot to Röntgen 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