title: Bonding nature and structural phase transition in fullerene based nanomaterials.
abstract: Rare-earth-metal-doped fullerides with a nominal composition of R3C70 (R = Sm, Eu, Yb) adopt a pseudomonoclinic structure in which C70 dimers glued with rare-earth ions are involved. High-temperature powder X-ray diffraction experiments revealed that the dimers undergo reversible first-order structural phase transitions, associated with reduction of the unit cell volume, similar to the results observed in previous high-pressure experiments. Structural analyses showed that C70 molecules are realigned to form closely packed structures, causing a reduction of volume at high temperature. The derived charge density map indicates that the transitions can be regarded as reversible structural changes from fullerene dimers to monomers. These features are ascribed to the unique bonding nature of rare-earth C70 compounds.
authors.affiliation: Japan Advanced Institute of Science and Technology, Tatsunokuchi, Ishikawa 923-1292, Japan.
authors.forename: Dam Hieu
authors.initials: DH
authors.lastname: Chi
authors.forename: Y
authors.initials: Y
authors.lastname: Iwasa
authors.forename: M
authors.initials: M
authors.lastname: Takata
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D037741:Fullerenes / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D044367:Phase Transition; D013499:Surface Properties
chemical_list: D037741:Fullerenes; D046911:Macromolecular Substances