Recent advances in the synchrotron technology make possible X-ray diffraction with beam spots smaller than a micrometer. These advances create many new possibilities for studying structures of materials in chemistry, physics, materials science, engineering, biology and geosciences that can improve our understanding of our planet, new materials, failure of materials, and life itself. Experiments with such intense, compact sources and microcrystals, however, change powder diffraction to a single- or few-crystal studies that may yield much more detail about structures. The principal goals of this developmental project are to make structural analysis by X-ray diffraction with micrometer sources and samples as straightforward and productive as studies with larger samples and to develop software for instrument control and data analysis that will readily transfer to a wide range of these applications and many synchrotrons. The project builds upon work by Dera, Downs, Mao, Prewitt, and Somayazulu to enable single-crystal diffraction studies with samples of micron dimensions in diamond-anvil cells at megabar pressures, work by Denton to develop novel detectors for these applications, and the availability of new micro-focus diffraction beamlines at the Advanced Photon Source and Advanced Light Source. While studying materials at extremely high pressures is the particular focus for these developments, potential applications of the results for diffraction work extend broadly in the sciences and engineering. Among the novel experimental approaches to structural determination with micron samples we plan to develop are: using limited area detector data with a monochromatic source to determine rapidly unit cells and determining peak intensities with a point detector; using high precision rotation stages and fast area detectors to collect a full data set in one oscillation pattern and computing unit cell parameters with efficient algorithms; automating a combined Laue & EDX approach for determining unit cell dimensions and extending it towards structure solution applications; developing a foil-mask X-ray area detector spectrometer based on stacked CMOS detectors separated by energy-selective masks, and resolving energies of Laue peaks by step-scanning monochromatic radiation and using high-readout-speed detectors.
Recent advances in the x-ray sources make possible X-ray studies with micrometer and nanometer beam spots and create new possibilities for understanding structures important to chemistry, physics, materials science, engineering, biology and geosciences. Detailed structural analyses can be done for fine grains within powders, rocks, and metal alloys. Engineering analyses of the strains in materials being deformed by stresses will be extended to much smaller sizes. Structures of natural or important technological materials will be determined under extreme conditions of pressure (more than a million atmospheres) and temperatures (from near absolute zero to more than 8000 degrees Celsius). These studies will help to improve our understanding of our planet, new materials, failure of materials, and life itself. The principal goal of the project is to make structural analysis with X-rays of small samples as simple as those done with automated commercial X-ray instruments. While studying materials at extremely high pressures is the particular focus for these developments, applications of the results for the techniques and software for instrument control and data analysis will readily transfer to a wide range of applications in science and technology.
