Dark Field X-ray Microscopy: A Synchrotron-based Rock’n Roll Imaging

Macroscopic physical and mechanical properties of many technological materials are determined by their hierarchically-organized structures such as grains, domains, and defects. These structures span over length scales ranging from nanometers to millimeters. Understanding the interplay between these length scales is of critical importance not only for improving material properties but also for validation of multi-scale models. Here, we present Dark Field X-ray Microscopy (DFXM), a diffraction-based synchrotron method for probing 3D nanostructures with their associated strain and orientation in bulk materials. Analogous to dark-field electron microscopy, DFXM comprises an objective lens to magnify diffracting features from millimeter-sized samples. The resulting spatial and angular resolutions are on the order of 100 nm and 0.001°, respectively. DFXM is a full field imaging technique. This allows for recording 3D strain and orientation maps of the entire heterogeneity in a given grain within seconds to minutes, thus capturing time-resolved phenomena. The microscope can be coupled with coarser grain mapping methods such as 3DXRD and Diffraction Contrast Tomography (DCT) without having to dismount the sample. Here, we demonstrate the technique on examples such as structure and dynamics of ferrous and non-ferrous metal alloys, along with functional oxides and semiconductor materials.

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