Fig. 2
From: Three-dimensional localization of nanoscale battery reactions using soft X-ray tomography
Three-dimensional (3D) chemical state mapping. a Correlative distribution plots between the optical densities (ODs) of each voxel at 708.2 and 710.2 eV. b Histogram plot of the polar angles of the data points in a. The y-axis is expressed as a logarithmic scale for better visibility. The plot can be fitted with summation (black solid line) of two Gaussian distributions which are centered on low (magenta solid line, 27.48o) and high (cyan solid line, 65.0o) polar angles correspond to Li0.93FePO4 and Li0.02FePO4, respectively. c 3D chemical map (left) and its segmentation into three chemical phase groups (right). The presence of the Li α FePO4 (majority Fe2+, LFP) and charged Li β FePO4 (majority Fe3+, FP) were assigned colors red and blue, respectively (left). The voxels were separated into three distinct groups, indicating chemical phase group of each voxel, according to the polar angle. The red, green, and blue areas indicate LFP-rich (>70% Li α FePO4), FP-rich (>70% Li β FePO4), and Mixed (30–70% Li α FePO4, the rest being Li β FePO4) domains, respectively. The shading colors in a, b indicate the criteria for chemical segmentation. Scale bar, 500 nm
