The schematics of the operation of 3D electron diffraction mapping for FTNWs and the reciprocal-space geometric relationship of the recorded systematic electron diffraction patterns. (a) The geometric relationship between the systematic tilting range and the tilting axis, as well as the twinning axis of an ideal B₄C star-shaped FTNW. Here the origin of the tilting angle (i.e., 0°) is defined as that the incident electron beam is perpendicular to both of the tilting axis and the twinning axis (TA) of the FTNW. At the orientation of the tilting angle equal to 0°, the incident beam is parallel to the mirror-symmetric axis of the cross-section of the FTNW as indicated by the white dashed line. (b) The recorded systematic tilting electron diffractions. These diffraction patterns share a common feature of a set of diffraction spots along an invariant line (indicated by red dashed line) which is parallel to the tilting axis. The green rectangles indicate the data-extracted areas which are used for the post data process of the 3D reconstruction of the diffraction intensity of specific reflections. (c) The geometric relationship of the recorded diffraction patterns in the reciprocal space. For simplicity of the presentation, here we only show nine diffraction patterns in panels (b) and (c).