Figure 2 : The effect of shape on the 3D crystals of superball colloids.

From: Observation of solid–solid transitions in 3D crystals of colloidal superballs

Figure 2

(a) Schematic set-up of the μrad-SAXS set-up used to investigate the 3D structure of the superball sedimentary crystals. (Inset) Photograph of a sample displaying optical Bragg reflections. (b) Transmission electron microscopy image of a hollow superball particle with m=3.6 and numerically calculated 2D form factor P(q) for the shown orientation. For the anisotropic hollow superballs (m>2) P(q) is also anisotropic, showing a distinct square pattern. (c) Schematic representation of a close-packed rhombohedral lattice (RC) aligned to the capillary wall and 2D structure factor S(q) for m=3.6. S(q) is described by reciprocal space vectors b1 and b2 and their angle, β, with a range of 60°→90°, corresponding to the real space RC angle α, with a range of 120°→90. (d,e) Selected experimental 2D μrad-SAXS patterns of the superball sediments showing mono-crystalline regions with RC symmetry. (f,g) Extracted profiles along the q-wedges and azimuthal rings of the 2D pattern in e. (f) I(q) profiles along i–iv q-wedges and (g) normalized I(ϕ) profiles of the different qhkl diffraction peaks, the curves are offset for clarity.