New Ordered Structure of Amorphous Carbon Clusters Induced by Fullerene-Cubane Reactions.

As a new category of solids, crystalline materials constructed with amorphous building blocks expand the structure categorization of solids, for which designing such new structures and understanding the corresponding formation mechanisms are fundamentally important. Unlike previous reports, new amorphous carbon clusters constructed ordered carbon phases are found here by compressing C H /C cocrystals, in which the highly energetic cubane (C H ) exhibits unusual roles as to the structure formation and transformations under pressure. The significant role of C H is to stabilize the boundary interactions of the highly compressed or collapsed C clusters which preserves their long-range ordered arrangement up to 45 GPa. With increasing time at high pressure, the gradual random bonding between C H and carbon clusters, due to "energy release" of highly compressed cubane, leads to the loss of the ability of C H to stabilize the carbon cluster arrangement. Thus a transition from short-range disorder to long-range disorder (amorphization) occurs in the formed material. The spontaneous bonding reconstruction most likely results in a 3D network in the material, which can create ring cracks on diamond anvils.