C sub 60 transformations at high pressures
C{sub 60} molecules have been studied at bodi shock and static high pressures. Under shock compressions C{sub 60} fullerenes are stable into the 13--17 GPa prrssure range. The onset of a fast ({approximately}0.5 ps) reconstructive Information to graphite occurs near 17 GPa. The graphite recovered from 27 GPa and about 900 K is relatively well with L{sub a}. Above 50 GPa a continuous transformation to an amorphous state is observed in recovered specimens. A transparent, metastable carbon phase was recovered from thin films of C{sub 60}, shocked to 69 GPa and 2200 K and then rapidly quenched to 1000 K. The selected area diffraction patterns indicate that the metastable carbon contains an amorphous diamond and n-diamond. Under hydrostatic compressions C{sub 60} molecules transform reversibly to a semi-transform phase in the pressure range of 15--25 GPa with a large pressure hysteresis. The high pressure phase consists of interconnected strongly interacting C{sub 60} agglomerates, or networks of fullerenes, whose stability continuously increases with increase of pressure. Above 27 GPa the transition becomes irreversible, and the material recovered from high pressure is metastable and diamond-like at ambient conditions. These pressure-induced transitions are explained in terms of {pi}-electron rehybridization between C{sub 60} molecules, which occurs at substantially decreased intermolecular distances.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 7039504
- Report Number(s):
- UCRL-JC-110324; CONF-920402--52; ON: DE92019546
- Country of Publication:
- United States
- Language:
- English
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