Fig. 1: Design and verification of the dislocation-driving strategy.
From: Dislocation-driven growth of single-crystal metal foils with high-index facets
a Schematic illustration of the thermodynamic mechanism, where Ed and Es refer to dislocation energy and surface energy per unit volume, respectively. b Schematic growth process of a single-crystal foil by driving the abnormal grain growth (AGG) of a high-index facet with the dislocation-driving strategy. The activated high-index facet is surrounded by a strong (100) texture, in which the adjacent (100) grains show higher dislocation density. The blue, green, yellow and red areas denote the density of geometrically necessary dislocation (GND) ranging from low to high. c–f Photographs of the pristine polycrystalline Cud/t foil (Cu with appreciable ΔEd and strong (100) texture) (c) and that after annealing for 20 s (d), 100 s (e) and 150 s (f), showing the abnormal growth of a high-index facet into a large single-crystal. The sample in (d–f) was oxidized at 180 °C for 2–5 min to show the growing high-index facet with a light color. g–j Electron backscatter diffraction (EBSD) inverse pole figure in the normal direction (IPZ) maps of the pristine polycrystalline Cud/t foil (g) and that after annealing for 20 s (h), 100 s (i) and 150 s (j), corresponding to the position marked by the white spot in (c–f). Low-angle and large-angle grain boundaries in h and i are highlighted in pink and white to correlate with the GND distribution in l and m, respectively. k–n EBSD GND density maps of the pristine polycrystalline Cud/t foil (k) and that after annealing for 20 s (l), 100 s (m) and 150 s (n). o–r EBSD inverse pole figure (IPF) contours of the pristine polycrystalline Cud/t foil (o) and that after annealing for 20 s (p), 100 s (q) and 150 s (r); color bar represents the signal intensity of different facets in IPF contour. The evolution of signal intensity indicated that the (100) texture first strengthened and then weakened due to its competitive growth with the high-index facets. Inset, IPF scatter plot shows the transformation from a polycrystal into a single crystal with the high-index facet.
