On-site preparation of one-dimensional C₆₀ polymer crystals

The preparation of large crystals is highly important for the characterization and application of a newly found structure but remains a challenge for one-dimensional (1D) C₆₀ polymers. In this work, we successfully fabricated a 1D C₆₀ polymer crystal via on-site annealing of a millimeter-sized C₆₀ molecular crystal with α-Li₃N at 500 °C and ambient pressure. Characterizations show that the C₆₀ cages in the crystal have been efficiently connected, forming 1D chains along the <110> direction in an orthorhombic 3D structure. At the same time, the crystal maintains a morphology similar to that of the pristine C₆₀ crystal, providing opportunities for characterization of all the facets of the crystal via Raman spectroscopy and thus suggesting the formation mechanism of such crystals.