Quasicrystalline order in self-assembled binary nanoparticle superlattices

Well-connected quasicrystals Quasicrystals are unique materials combining long-range order with 'impossible' packing symmetries like fivefold rotation, forbidden in periodic structures. Until now, they have been found only in specific systems such as intermetallic compounds, block copolymers, or colloidal particles under the action of a laser standing-wave pattern. Now Talapin et al . have self-assembled colloidal nanoparticles into aperiodic quasicrystalline lattices by carefully tailoring their sizes and using a novel packing motif. They can obtain quasicrystals with nanoparticles made of several different combinations of materials, pointing to the fact that only sphere packing and simple inter-particle potentials are important for their formation, and not specific interactions between the components These quasicrystals can also connect to the ordinary (crystalline) world through a thin 'wetting' layer with structures resembling the classic Archimedean tiling pattern. Quasicrystals are ordered structures that lack any translational symmetry, challenging the classic conception of ordered solids as periodic structures. So far, they have been reported in certain systems and can, for example, form from intermetallic compounds and organic dendrimers. Here it is shown that colloidal inorganic nanoparticles from several materials can self-assemble into binary aperiodic superlattices with quasicrystalline order. The discovery of quasicrystals in 1984 changed our view of ordered solids as periodic structures 1 , 2 and introduced new long-range-ordered phases lacking any translational symmetry 3 , 4 , 5 . Quasicrystals permit symmetry operations forbidden in classical crystallography, for example five-, eight-, ten- and 12-fold rotations, yet have sharp diffraction peaks. Intermetallic compounds have been observed to form both metastable and energetically stabilized quasicrystals 1 , 3 , 5 ; quasicrystalline order has also been reported for the tantalum telluride phase with an approximate Ta 1.6 Te composition 6 . Later, quasicrystals were discovered in soft matter, namely supramolecular structures of organic dendrimers 7 and tri-block copolymers 8 , and micrometre-sized colloidal spheres have been arranged into quasicrystalline arrays by using intense laser beams that create quasi-periodic optical standing-wave patterns 9 . Here we show that colloidal inorganic nanoparticles can self-assemble into binary aperiodic superlattices. We observe formation of assemblies