A Single-Component Silicon Quasicrystal

Quasicrystals are structures with long-range order and no translational periodicity. Monatomic quasicrystals were predicted for model potentials, but no single-component atomic quasicrystal of an actual element has been reported to date. A dodecagonal quasicrystal was recently predicted to form in bilayer water. Water and silicon present striking similarities in their phase behavior, raising the question of whether quasicrystals may occur in silicon. Here, we show, using molecular simulations, that a confined silicon bilayer forms a quasicrystal upon compression between smooth surfaces. The quasicrystal is stable in a narrow region of the phase diagram and forms spontaneously upon cooling the liquid bilayer in a wide range of pressures. Cooling the liquid between atomically detailed plates incommensurate with the quasicrystal leads to its spontaneous formation at 1 atm of lateral pressure. This suggests that the silicon quasicrystal could be obtained in experiments at room pressure by tuning the structure and interactions of the surfaces.