Crystallographically Preferred Growth in Self-assembled Colloidal Crystals: A Mechanistic Study*

Crystalline atomic and ionic solids are often textured due to preferred growth along specific crystallographic orientations. In this talk we demonstrate that crystallographically-preferred growth can also be observed in colloidal crystals through an evaporation-induced self-assembly process. By using quantitative crystallographic mapping, we find that the preferred <110> growth in the fcc lattice of the colloidal crystal is achieved through a gradual crystallographic rotation, facilitated by geometrically necessary dislocations (GNDs). Complementary microscopic investigation at the single-particle level indicates that, similar to crystalline metals, individual dislocations disassociate to two Shockley partial dislocations, creating a hcp stacking fault in the fcc lattice. We show that the origin of these dislocations is drying-induced tensile stress in the meniscus direction in the colloidal crystal and that the associated experimentally observed primary slip systems are consistent with the classical atomistic theory, giving rise to GNDs of the same slip system that rotate individual grains to the <110> direction to minimize stress.