The development of advanced materials, used in modern manufacturing and technology, represent a "key enabling technology" underpinning industrial competitiveness and supporting contemporary lifestyles. Moreover, advances in materials science are intimately linked to advanced materials characterisation; the insight that such studies bring to understanding the behaviour and properties of a system leads ultimately to the development of improved materials. Thus materials research goes hand in hand with investigation via synchrotron radiation, particularly exploiting the X-ray energies available at a high-energy synchrotron like the ESRF. Studies by diffraction and spectroscopy reveal the composition, atomic structure, and crystalline state of materials, and imaging allows defects and aggregates to be observed. In situ studies can be particularly effective to follow materials under realistic operating conditions to watch their evolution in a working environment.
The highlights presented in this chapter are chosen from ESRF and CRG beamlines engaged in the broad field of research into materials systems, principally at the level of fundamental science, though it should be emphasised that ESRF beamlines can be equally exploited for analyses in the domain of applied research. The articles illustrate studies of bulk materials and the characterisation of surfaces and interfaces, and cover a number of themes.
One theme is the use of highly focussed X-rays and/or complementary microscopic probes to investigate nanostructures such as nanorods and nanocrystals (themselves often produced via an advanced procedure), to extract detailed information about structure, shape, orientation, defects, stress and strain. These are characteristics that have a profound influence on physical behaviour. A second theme is the interactions between molecules and surfaces as surfaces control the growth and structure of layers with potentially unique optical or electronic properties, for example for the development of molecular electronic devices. The techniques used include surface diffraction, reflectivity and X-ray standing wave analysis, coupled where appropriate with theoretical modelling of the interactions. Chemical interactions and the behaviour of molecules at surfaces are keys to discovering the mechanisms of heterogeneous catalysis, for example for the conversion of car exhaust gasses into less harmful emissions. In situ investigation of such systems, under realistic conditions of temperature and pressure, by surface diffraction, hard-X-ray diffraction and absorption spectroscopy can give new insights into the sometimes complex series of steps in such reactions. In another example, an investigation was carried out in a molten salt environment at 900°C, allowing elucidation of the pathway for the electrochemical extraction of titanium via the recently devised FFC Cambridge process that has potential for the production of Ti (and other metals and alloys) with more efficiency than current processes. Finally, materials scientists and chemists are continually devising new materials, and improving or discovering new properties for old ones. The technique of X-ray diffraction is used to examine the structural properties often under changing external conditions, e.g. under an electric field for potential piezoelectric materials, as a function of temperature for substances with electronic or magnetic ordering or superconductivity, or with varying chemical environment for porous materials allowing a detailed investigation of the adsorption of volatile materials. Such studies produce a wealth of new information, unavailable by other means.
Within the Experiments Division Structure of Materials Group, planning for the upgrade continued with the arrival of Tobias Schulli to take over as scientist responsible for ID01/UPBL1. A recent workshop was held to discuss how ESRF could better serve the needs of the metallurgy community, particularly via the capabilities of the high energy beamline ID15A. In the upgrade, part of ID15’s programme will be transferred and optimised at the nanofocus high-energy UPBL2. This year, a refractive lens transfocator was installed at ID15 (similar to that installed last year on ID11) allowing great flexibility for focussing or condensing the beam. Both ID11 and ID01 continue their development and will be installing new, high-precision diffractometers early in 2011.