Development of spectromicroscopes for multiscale observation of heterogeneity in materials at photon factory, IMSS, KEK

We have developed hard X-ray spectromicroscopes at various scales using synchrotron radiation to elucidate the origin of the function of materials at Photon Factory (PF), Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK) in Japan. One is a 2D scanning X-ray microscope with ~20-μm spatial resolution at BL-15A1 in PF; another is full-field 3D X-ray computed tomography (X-CT) with a resolution down to 30 nm at NW2A in PF-AR. In both techniques, not only morphological images but also X-ray absorption spectra (XAS) at any pixel or voxel of interest can be obtained by changing the X-ray energy. These XAS imaging techniques are useful for understanding the chemical states of specific elements and investigating reaction mechanisms. We have applied these techniques to various materials and elucidated the change of heterogeneity in chemical states which determines macroscopic properties. Application to heterogeneous reduction in iron ore sinters demonstrated clearly the impact of this approach; the multi-scale heterogeneity from 50 nm to 20 μm was shown to be related to trigger sites, which determine the degradation of iron ore sinters during reduction.