Stable three-dimensional metallic carbon with interlocking hexagons

Carbon is an amazing material: it not only forms the chemical basis for all known life but also, because of its rich physics and chemistry, displays an array of structures: from the age-old graphite and diamond to more recent C₆₀ fullerene, 1D nanotube, and 2D graphene. One of the unsolved issues in carbon science has been to find a 3D form of carbon that is metallic under ambient conditions. This paper addresses this important challenge. Using state-of-the-art theoretical calculations, we predict the existence of such a phase that is formed from interlocking hexagons and is dynamically, mechanically, and thermally stable. It is suggested that this new form of carbon may be synthesized chemically by using benzene or polyacenes molecules.