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abstracts
From the first quasicrystal discovered in the laboratory 30 years ago to the only known specimen of naturally occurring quasicrystals, quasicrystals with icosahedral symmetry have received great attention. There are more than one hundred stable icosahedral quasicrystals in metallic alloys; all are identified by their diffraction spectra. Despite this abundance, resolving the positions of the atoms within the solid has been possible only indirectly. Moreover, unlike dodecagonal and other axial quasicrystals, icosahedral quasicrystals have been observed neither in simulations nor in non-atomic (e.g. micellar or colloidal) systems, where real-space information would be available. Here we present an icosahedral quasicrystal discovered in computer simulation via self-assembly from the liquid phase. We provide a structure model by analyzing atomic surfaces and report the presence of phason flips. Our results constitute a direct microscopic confirmation of the higher-dimensional crystallographic description of icosahedral quasicrystals.
abstracts
A primary challenge for the development of bulk, scalable, and high yield materials with interesting properties is the limited number of structures that can be obtained via self-assembly of nano and micrometer sized particles. Systematic and extensive computational studies of hard polyhedral particles have demonstrated that anisotropy of the building blocks can be a viable route for increasing variability of assembled patterns [1, 2, 3]. Interestingly, the types of structures assembled from this method were shown to be predictable from information contained already in the dense fluid, prior to crystallization. In this talk, the role of such local structures for self-assembly will be rationalized and we will demonstrate how this information can be used as a strategy for design of crystalline and quasicrystalline patterns for both symmetric and asymmetric particles.
