resumo
Fullerite is a solid composed of pseudospherical C-60 molecules with strong covalent intramolecular C-C bonds and weak intermolecular van der Waals interactions. The discovery of their one-dimensional- (1D), 2D-, and 3D-polymerized forms has renewed the interest of compressibility studies of clathrate phases composed of a continuous network of mainly sp(3) carbon atoms. Using accurate x-ray-diffraction measurements performed under high pressure, we report the room-temperature pressure-volume equation of state of anisotropic 3D C-60 polymer up to 35 GPa. A very high bulk modulus of 288 GPa has been extracted from the fitting of the unit-cell volume to a Vinet equation of state and confirms the very high stiffness of this low-density material. Two different linear compressibilities (231 and 320 GPa) were obtained, respectively, along the axial direction and the radial direction of the elliptical Debye-Scherrer diffraction patterns indicating the presence of two types of intermolecular bonds. No phase transition or collapse of the C-60 cages was observed during compression. The pseudo-fcc 3D C-60 polymer remains stable up to 35 GPa and is thus, through multiple intermolecular sp(3) bonding, the most stable form of fullerite.
palavras-chave
HIGH-TEMPERATURE TREATMENT; HIGH-PRESSURE; PHASE-TRANSFORMATIONS; ROOM-TEMPERATURE; SOLID C-60; CARBON; DIAMOND; COMPRESSIBILITY; C60; CRYSTALLINE
categoria
Physics
autores
Mezouar, M; Marques, L; Hodeau, JL; Pischedda, V; Nunez-Regueiro, M
nossos autores
