High‐temperature Transitions of C₆₀ at Moderate Pressures

Abstract

We have prepared new nanocarbon phases using high‐temperature (1000–1600 K) treatment of C₆₀ at moderate (0.1–1.5 GPa) pressures attainable for large‐volume high‐pressure apparatus. The structure of the phases has been studied by x‐ray diffraction and high resolution transmission electron microscopy (HRTEM). The Raman spectra and electron energy loss spectroscopy (EELS) provide evidence of the sp ² bonding in the new materials. Mechanical and elastic properties are also presented. Whereas the values of density for the new nanocarbon phases are lower than that of graphite, they are still quite hard materials (H≈10–15 GPa) and have a high (∼90%) elastic recovery and record high values of the hardness‐to‐Young modulus ratio H/E≈0.17–0.22.

Keywords:

• Carbon
• C₆₀
• Nanomaterials
• Hardness
• Elasticity
• Elastic recovery

ACKNOWLEDGMENTS

The authors are grateful to S.V. Popova, V.A. Davydov, A.A. Pozdnyakov, and V. Richard for the assistance in the experiments and for useful discussions. The work has been supported by the Russian Foundation for Basic Research (05‐02‐16596 and 07‐02‐01275), by the Agence Nationale de la Recherche (grant NT05‐3_42601), by the Russian Science Support Foundation and by the Programs of the Presidium of RAS. VVB has been receiving support from the Université Paris Nord.