Characterization of nanostructured materials by synchrotron high-energy X-ray scattering

The availability of high-flux and high-energy synchrotron X-rays has significantly advanced the field of materials research because of the large penetration and low absorption of high-energy X-rays, and their weak interaction with matter. Synchrotron high-energy X-ray diffraction facilities provide great research opportunities, especially, for in situ and operando structural characterizations of materials in real time and in realistic conditions in broad research fields ranging from condensed matter, materials science and engineering to energy science. In this overview we will briefly introduce synchrotron high-energy X-rays in comparison with conventional lab X-ray sources and other low energy X-rays. Some general formulae about high-energy X-ray diffraction and pair-distribution-function analysis will be concisely described, together with some experimental facilities for in-situ high-energy X-ray measurements. We will focus on the high-energy X-ray diffraction techniques and their application on structural characterization of nanoscale materials for energy applications, with a special emphasis on the in-situ and operando studies. We will demonstrate that high-energy X-rays are very powerful to probe in-situ nanophase formation and growth at liquid/solid interface and in solution. High-energy X-ray total scattering coupled with pair-distribution-function analysis and computer modeling and simulations are widely used to study nanoparticles and will be presented here. Recently following the world-wide effect in rechargeable battery technology, high-energy X-rays have been extensively employed to monitor in-situ nanoscale electrode materials during synthesis as well as probe in-situ chemical reaction of electrode/electrolyte during thermal runaway, which is a critical issue for battery safety. High-energy X-rays are also particularly suited for non-destructive in-operando characterization of bulk commercial batteries to reveal the electrochemical processes of real materials in real time and normal operational and abuse conditions. Finally, we will present recent work to show the unique capability of high-energy X-rays for in-situ exploration of the superior mechanical properties of a new class of metal nanocomposites which are built of nanowires embedded in a shape memory alloy matrix.