Fig. 2.

Hexagonal prisms with varying unit cell compositions. a–c SEM images and one-dimensional SAXS patterns of hexagonal prism microcrystals from an AB₂ lattice synthesized from different sets of PAEs to achieve a range of β/α: a 0.67, b 0.73, and c 0.80 (scheme shown on left). The systems shown in a and b each consist of a pair of nanoparticles; one has an Au core diameter of 15 nm and the other is 5 nm. In the case of the small particle, the hydrodynamic radius was deliberately changed by changing the thickness of the DNA shell so that the β/α in b is greater than in a. The system in c used the same 15 nm Au core PAEs that were used in a and b, but the hydrodynamic radius was varied by changing the Au core diameter of the small particle (10 nm in diameter) so that the β/α in c is greater than in a. In the SAXS patterns, the black trace is the experimentally obtained scattering pattern, and the red trace is the predicted scattering pattern for a model lattice. The lattice parameters from SAXS results were used to calculate the c/a ratio of each unit cell. Scale bars are 1 μm