Selective Cleavage of Periodic Mesoscale Structures: Two-Dimensional Replication of Binary Colloidal Crystals into Dimpled Gold Nanoplates

摘要

Specific crystallographic planes of binary colloidal crystals consisting of silica nanopartides are two-dimensionally replicated on the surface of gold nanoplates. The selectivity of the surface patterns is explained by the geometrical characteristics of the binary colloidal crystals as templates. The binary colloidal crystals with the AlB_2- and NaZn_(13)-type structures are fabricated from aqueous dispersions of stoichiometrically mixed silica nanopartides with different sizes. The stoichiometry is precisely controlled on the basis of a seed growth of silica nanopartides. Dimpled gold nanoplates are formed by the two-dimensional growth of gold between partially deaved surfaces of templates. The selectivity of the surface patterns is explained using the AlB_2-type binary colloidal crystal as a template. The surface pattern is determined by the preferential cleavage of the plane with the lowest density of particle-particle connections. The tendency to form well-defined deavage in binary colloidal crystals is crucial to formation of dimpled gold nanoplates, which is explained using the NaZn_(13)-type binary colloidal crystal as a template. Its complex structure does not show well-defined cleavage, and only distorted nanoplates are obtained. Therefore, the mechanism of the two-dimensional replication of binary colloidal crystals is reasonably explained on the basis of their periodic mesoscale structures and crystal-like properties.