Novel alloys, ceramics, and composites with attractive mechanical, structural or electronic properties exhibit complex ordering (microstructure) at varies length scales from conventional continuum down to atomic scales. It clearly necessary to characterize the microstructure in details, preferably as it evolves under critical operation conditions. High intensity, non-destructive synchrotron x-ray absorption and scattering techniques are ideally suited for in-situ characterization.
I will present a short overview of properties of synchrotron radiation, synchrotron x-ray instrumentation, and synchrotron facilities followed by physical principals behind x-ray absorption fine structure (XAFS), x-ray magnetic circular dichroism (XMCD), energy dispersive x-ray diffraction (EDXRD), coherent x-ray scattering (CXS), and meV-eV resolved inelastic x-ray scattering (IXS).
Finally, I will present several personal examples of using XAFS and EDXRD to deal with challenging Material Science and Engineering applications. Most of experimental data were collected at the National Synchrotron Light Source of Brookhaven National Laboratory. Two solutions of local structure obtained by XAFS will be considered. The first is of amorphous Co-doped PECVD grown C2BlOHx semiconducting boron carbides in which the Co atoms are found to be fivefold boron coordinated and chemically bonded to the icosahedral cages of B lOCHx or B9C2Hy. In the second, the structural/chemical phase composition of Ti- and Ni- species, which catalyzes complex metal hydrides, is determined from combined XAS, DFT and MD simulations. Two examples of using EDXRD include a strain mapping of the detailed elasto-plastic response of nanostructured and microstructured alumina-titania ceramic coatings on the Ti-alloy substrates and in-situ crystalline phase profiling inside operational commercial batteries.
Host: Tom Tsakalakos