ABSTRACT
Following the rst years of the discovery, a second great achievement drew the attention of the materials science community: It was shown that a solid material could be made out of C60 molecules [2]. e solid C60 is formed by a close-packing arrangement of the fullerene molecules. One way to do that is to dispose the molecules in the lattice sites of a face-centered cubic structure. is is a typical molecular solid, that is, the molecules,
which are the building blocks of the crystals, do not interact through strong covalent bonds, but, rather, stay apart from each other interacting through weaker van der Waals interactions. e region between fullerenes in the crystal may be occupied by other elements or molecules. is is the case of a doped structure, and C60 also revealed intriguing behavior in this aspect. Metallic elements, such as potassium, could be intercalated in the structure in the stoichiometry K3C60, giving rise to a metallic behavior [3]. Moreover, the superconducting critical temperature was found [4] to be 18 K, which is an astonishing result when compared with a similar intercalation in graphite, which presents a transition temperature of a few tenths of a Kelvin [7]. Other metallic elements could also dope the solid C60, such as rubidium, raising [5,6] the superconductivity critical temperature to 29 K.
