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Figure 1
HRTEM image and structural models of a D-twin boundary. (a) A low-magnification TEM image of a spherical particle with an icosahedral cavity in the centre, where a schematic illustration is given in the inset. (b) An HRTEM image of a sliced sample taken from the common [[0\bar 11]] axis. The inset shows a hypothetical image obtained by mirroring a simulated HRTEM with an offset value of 0.5, showing that the twin boundary is {111} + 0.5. The white contrasts correspond to regions with low electrostatic potential. (c) The Fourier transform of the HRTEM image shown in (b). (d) A superposition of two simulated ED patterns (red and blue), where the 111 reflections of both domains overlap with each other (black). (e) The topology of a D-twin boundary shown as skeletal graphs, in which the 5-connected vertices are highlighted with yellow circles. (f) A 3D model of the D-twin boundary obtained by joining two 3D reconstructed copies, shown in (g), at {111} + 0.5.

IUCrJ
Volume 7| Part 2| March 2020| Pages 228-237
ISSN: 2052-2525
https://doi.org/10.1107/S2052252519017287