Complex hierarchical microstructures spanning multiple length scales are common in functional materials today and are likely to become more prevalent in the future. The development and optimization of these materials require powerful structure characterization tools with capabilities matching the complexity of the problem. A versatile materials microstructure and structure characterization facility at the Advanced Photon Source (APS) strives to provide such capabilities by combining Bonse-Hart ultra-small-angle X-ray scattering (USAXS) with pinhole SAXS and wide-angle X-ray scattering (WAXS) measurements. Making use of Si 440 crystal optics and high-energy X-rays, this unique combination provides characterization capabilities over 5 decades in scale range - from over 20 micrometers as an upper length scale down to below 1 Å. The maximum allowable feature size matches that of contemporary ultra-small-angle neutron scattering (USANS) instruments, while the X-ray flux of 1012-13 photons/second enables rapid in situ measurements. Recent implementation of on-the-fly scanning of the USAXS instrument allows complete characterization over this entire size range in under 3 minutes.
Multiple additional capabilities have been developed recently and are now available to the user community:
USAXS-XPCS: Taking advantage of the coherence in the X-ray beam and using a 2D collimated USAXS geometry, the internal dynamics of materials can be studied with millisecond time resolution by X-ray photon correlation spectroscopy (XPCS) in USAXS-XPCS measurements over a microstructure scale range from ≈ 100nm to several micrometers.
USAXS Imaging: The capability to characterize large microstructural features, within a field of view of ≈ 1 mm with 1 µm spatial resolution is achieved in transmission-geometry USAXS imaging where the USAXS crystal analyzer is set to specified momentum transfer values, Q.
Future plans: The planned APS upgrade to incorporate a multi-bend achromat (MBA) storage ring design will provide significant improvement in X-ray beam coherence and brightness. This will result in major advances in USAXS-based techniques, especially in USAXS-XPCS and USAXS imaging. Current plans for the existing facility included development of USAXS imaging tomography to provide 3D characterization capabilities with ≈ 1 µm resolution and 1 mm field of view.
Meanwhile, to meet a growing demand for in-operando/in-situ studies, increasingly sophisticated “non-X-ray” measurement capabilities are being developed to allow the user to characterize materials microstructure and/or structure, and materials properties and/or performance simultaneously. In this context, specific sample cell geometries can be designed through collaboration between users and APS staff, and then manufactured at the APS.
The presentation will review the current status of this versatile materials characterization facility and present scientific examples enabled by its unique capabilities.