C 60 one- and two-dimensional polymers, dimers, and hard fullerite: Thermal expansion, anharmonicity, and kinetics of depolymerization

We report on high-resolution thermal expansion measurements of high-temperature-pressure treated C60 [one-dimensional (1D) and (2D) polymers and “hard fullerite”], as well as of C60 dimers and single crystal monomer C60 between 10 and 500 K. Polymerization drastically reduces the thermal expansivity...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 1999, Vol.60 (24), p.16920
Main Authors: Nagel, Peter, Pasler, Volker, Lebedkin, Sergei, Soldatov, Alexander, Meingast, Christoph, Sundqvist, Bertil, Persson, Per-Axel, Tanaka, T., Komatsu, K., Buga, Sergei, Inaba, Akira
Format: Article
Language:English
Subjects:
activation energy
C60
C70
Condensed matter physics
diamond
dimers
fullerene polymers
Fullerenes
Fysik
hard fullerite
high pressure synthesis
Kondenserade materiens fysik
linear polymer chains
NATURAL SCIENCES
NATURVETENSKAP
orthorhombic polymer
Physics
tetragonal polymer
thermal depolymerization
thermal expansion
two-dimensional polymers
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Summary:We report on high-resolution thermal expansion measurements of high-temperature-pressure treated C60 [one-dimensional (1D) and (2D) polymers and “hard fullerite”], as well as of C60 dimers and single crystal monomer C60 between 10 and 500 K. Polymerization drastically reduces the thermal expansivity from the values of monomeric C60 due to the stronger and less anharmonic covalent bonds between molecules. The expansivity of the “hard” material approaches that of diamond. The large and irreversible volume change upon depolymerization between 400 and 500 K makes it possible to study the kinetics of depolymerization, which is described excellently by a simple activated process, with activation energies of 1.9±0.1 eV (1D and 2D polymers) and 1.75±0.05 eV (dimer). Although the activation energies are very similar for the different polymers, the depolymerization rates differ by up to four orders of magnitude at a given temperature, being fastest for the dimers. Preliminary kinetic data of C70 polymers are presented as well.
ISSN:1550-235X
1098-0121
DOI:10.1103/PhysRevB.60.16920