Lattice vibrations and thermodynamic stability of polymerized C60 deduced from heat capacities

• Heat capacities of 1D and 2D pressure polymerized C60 as well as the thermally depolymerized C60 have been measured at temperatures between 4 and 350 K and the results analyzed for the lattice vibrations and the thermodynamic stability. It was found from the low-temperature heat capacity (T < 100 K) that on polymerization (1) the lattice vibrations, both translational and rotational, stiffen substantially, (2) an anisotropic nature emerges in response to the lower dimensionality, and (3) an anharmonicity still remains as in pristine C60. The normal C60 has an excess entropy of 67.8 and 99.4 J K – 1 mol – 1 at 300 K relative to the 1D and 2D polymerized C60, respectively. The thermodynamic stability is considered with two possible phase diagrams.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

Fullerenes

C60

specific heat

heat capacity

polymer

dimer

high pressure synthesis

lattice dynamics

phase diagram

phase stability

plastic crystal

entropy

order-disorder transformation

one-dimensional polymer

two-dimensional polymer

Condensed matter physics

Kondenserade materiens fysik

fysik

Physics

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