Transmission X-ray microscopy-based three-dimensional XANES imaging

Full-field transmission X-ray microscopy (TXM) in conjunction with X-ray absorption near edge structure (XANES) spectroscopy provides two-dimensional (2D) or three-dimensional (3D) morphological and chemical-specific information within samples at the tens of nanometer scale. This technique has a broad range of applications in materials sciences and battery research. Despite its extensive applicability, 2D XANES imaging is subject to the disadvantage of information overlap when the sample thickness is uneven. 3D XANES imaging combines 3D TXM with XANES to obtain 3D distribution information on chemical states. A 3D XANES imaging method has been established at the Shanghai Synchrotron Radiation Facility (SSRF) and has been used to characterize the structure and chemical state of commercial LiNi_xCo_yMn_zO₂ (NCM, x + y + z = 1) battery powder materials. The imaging results provide a visual representation of the 3D chemical state information of the particles with depth resolution, allowing for the direct observation of 3D nickel oxidation. This paper will describe in detail the data acquisition, data processing, quantification and visualization analysis of 3D XANES imaging.