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A Shape‐Induced Orientation Phase within 3D Nanocrystal Solids
Author(s) -
Burian Max,
Karner Carina,
Yarema Maksym,
Heiss Wolfgang,
Amenitsch Heinz,
Dellago Christoph,
Lechner Rainer T.
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201802078
Subject(s) - nanocrystal , materials science , facet (psychology) , superstructure , phase (matter) , chemical physics , diffusion , nanotechnology , scattering , synchrotron , crystallography , optics , chemistry , thermodynamics , psychology , social psychology , physics , organic chemistry , personality , big five personality traits
When nanocrystals self assemble into ordered superstructures they form functional solids that may inherit the electronical properties of the single nanocrystals. To what extent these properties are enhanced depends on the positional and orientational order of the nanocrystals within the superstructure. Here, the formation of micrometer‐sized free‐standing supercrystals of faceted 20 nm Bi nanocrystals is investigated. The self‐assembly process, induced by nonsolvent into solvent diffusion, is probed in situ by synchrotron X‐ray scattering. The diffusion‐gradient is identified as the critical parameter for controlling the supercrystal‐structure as well as the alignment of the supercrystals with respect to the substrate. Monte Carlo simulations confirm the positional order of the nanocrystals within these superstructures and reveal a unique orientation phase: the nanocrystal shape, determined by the atomic Bi crystal structure, induces a total of 6 global orientations based on facet‐to‐facet alignment. This parallel alignment of facets is a prerequisite for optimized electronic and optical properties within designed nanocrystal solids.