Figure 6
Characterization of lamellar grain boundaries using 4-D XRT data.
(A) Semi-transparent 3-D microstructure of Si particle overlaid with meshes of the nearly planar grain boundaries (in blue and green). (B) Magnified bird's eye view of the boxed region in (A). The planarity of the grain boundaries suggests a high degree of coherency between the adjoining grains. The boundaries make an angle of approx. 110° with respect to the facet planes, which corresponds to the angle between two {111} interfaces of the same family. Thus, the lamellar grain boundaries are coherent {111} Σ3 (twin) boundaries. The angle of the re-entrant edge is 150°. (C) Propagation of the twinned interface in (B) during growth. Five semi-transparent isochrones are plotted (Δt ≈ 600 s) together with points along the two twin boundaries, labelled I and II and colored in blue and green, respectively. The color of the particle interfaces indicates the passage of time, thereby making the interfacial evolution more clear. The morphology of the twinned interface appears nearly identical between time-steps, i.e., the re-entrant groove does not disappear during growth, consistent with the Wagner-Hamilton-Seidensticker (WHS) model14,15.
