Materials science research investigates the fundamental relationships between the structure of materials and their properties. An understanding of how behaviour is linked to structure is a vital consideration in the development of materials with new attributes or improved performance. The examples described in this chapter are drawn from work conducted at both ESRF and CRG beamlines. The predominant technique exploited is diffraction, from which information about a material’s atomic structure and its microstructure can be derived. The former describes the arrangement of the atoms that form the basic building blocks of the substance, while the latter portrays the size, shape and aggregation of the grains that make up the bulk. Both are relevant since structural characteristics on all length scales are important in defining materials’ properties.

The samples investigated cover a very wide range and include: biological and biosynthesised systems; novel chemical materials with known or potential catalytic properties; pure chemical elements; ceramics; superconductors; metals and alloys. Crystalline and glassy solids, liquids, thin films and a quasicrystalline intermetallic alloy are represented. The hard-energy X-ray beams of ESRF beamlines are particularly well suited to such studies for they provide a combination of penetration through absorbing materials, high flux for fast measurements and high statistical quality, and excellent spatial and angular resolution. These ensure high quality data for the most complex of samples under demanding experimental conditions. Moreover, the newly extended and refurbished ID11 beamline will allow focussing of the X-ray beam to sub-micrometre dimensions for even greater spatial resolution. Other important techniques used to study materials at the ESRF include imaging, e.g. of voids, cracks or dislocations, reflectivity from thin films and interfaces, small-angle scattering from samples with structural features on the nanometre scale, absorption spectroscopy, etc.

Studies can be performed under a wide range of conditions, such as high and low temperature, at high pressures, or under extreme conditions when diamond anvil cells are coupled with laser heating. A recently-developed approach involves laser heating and aerodynamic levitation of the sample, thus eliminating any possible chemical reaction between the sample and its container or parasitic scatter from the sample environment. In situ measurements allow the detailed evolution of a material’s structure to be followed as it is processed or transforms from one form to another, e.g. solid to liquid, liquid to glass, etc. With fast multichannel detectors, high time resolution (e.g. 50 ms) can be used to follow transformations during rapid changes in temperature or other conditions.

Understanding these processes can be of great practical importance, for example quenching is a fundamental step in the production of glasses. For the fastest time resolution, needed to follow the steps of fundamental chemical processes such as photo-induced cleavage of a chemical bond, the pulsed nature of the synchrotron source must be exploited by means of the pump-probe approach, which gives time resolution down to 100 ps.

Of academic and practical relevance, the examples chosen are but a small subset of the numerous studies of complex materials performed in the past year. The accounts speak for themselves and illustrate the rich diversity of materials problems investigated at ESRF.

A. Fitch