Figure 3 : The superball shape changes the densely packed RC stacking sequence.

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

Figure 3

(a) For each of the superball shapes the structural angle, β, and ratio of the lattice spacing and the superball edge-to-edge length, d/L, were determined. The error bars of the latter represent the scaled standard deviation in superball size, σL/L. Good agreement is found with the theoretical β (black dotted line) expected for a close-packed (d/L=1, blue dashed line) rhombic crystal (RC) planes. (b,c) Schematic illustrations of the position of successive close-packed RC planes that can be either positioned into (b) the hollow-site (HRC) or (c) the bridge-site (BRC) position and the resulting 3D structure for both stacking sequences. (d) Numerically calculated 2D patterns of P(q) and S(q) for a superball shell with m=3.6 and shell thickness to length ratio, t/L=0.03. Due to constructive and destructive interference between the RC planes, only specific hkl peaks are allowed in the S(q) pattern for each of the two stacking sequences, resulting in a hexagonal pattern for HRC or a rhombic pattern for BRC, that are enhanced by P(q).