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Figure 2
Structural assessment of a D-twin boundary. (a), (b) Rendering of |ns·nb| on the side surfaces of the reconstructed silica wall at {110} + 0.5 and {111} + 0.5, respectively, shown within slab regions of thickness 0.2 in units of the relevant d spacings. (c) Sectional pore fractions calculated with the reconstructed silica wall, in which the {110} + 0.5 plane shows the highest contrast followed by the {111} + 0.5 plane. (d) Scatter plot of elevation angles of the surface normal vectors with respect to {111} planes plotted against the offset values, for the D surface (black) and its CMC companions (red and blue). (e), (f) Twin-boundary sections of polysynthetic D-twins constructed as minimal and CMC surfaces, respectively, viewed along a common 〈110〉 direction. Colour maps are overlaid to show the minimal distances in units of the d spacing from the un-twinned D surface, where deviations in opposite senses are shown in blue and red while coincidence is shown in white. In (f), small and large necks, as indicated by the `o' and `O' symbols, alternate along the boundary normal.

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