Integrated Calendar

The two natural allotropes of carbon, diamond and graphite, are extended networks of sp3- and sp2-
hybridized carbon atoms, respectively. By mixing different hybridizations and geometries of carbon, one
could conceptually construct countless synthetic allotropes. In this talk, I will introduce graphullerene, a
new two-dimensional superatomic allotrope of carbon combining three- and four-coordinate carbon
atoms. The constituent subunits of graphullerene are C60 fullerenes that are covalently interconnected
within a molecular layer, forming graphene-like hexagonal sheets. The most remarkable thing about the
synthesis of graphullerene is that the solid-state reaction produces large polyhedral crystals (hundreds of
micrometers in lateral dimensions), rather than an amorphous or microcrystalline powder as one would
typically expect from polymerization chemistry.
Similar to graphite, the crystals can be mechanically exfoliated to produce molecularly thin flakes with
clean interfaces—a critical requirement for the creation of heterostructures and optoelectronic devices.
We find that polymerizing the fullerenes leads to a large change in the electronic structure of C60 and the
vibrational scattering mechanisms affecting thermal transport. Furthermore, imaging few-layer
graphullerene flakes using transmission electron microscopy and near-field nano-photoluminescence
spectroscopy reveals the existence of moiré-like superlattices.
The discovery of a superatomic cousin of graphene demonstrates that there is an entire family of
higher and lower dimensional forms of carbon that may be chemically prepared from molecular
precursors.

Quasicrystals are exotic materials that have symmetries that once thought to be impossible for matter. The first known examples were synthesized in the laboratory 30 years ago, but could Nature have beaten us to the punch? This talk will describe the decades-long search to answer this question, resulting in one of the strangest scientific stories you are ever likely to hear.

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