High pressure polymerization of the Li-intercalated fulleride Li{sub 3}CsC{sub 60}
The structural features of the superconducting Li{sub 3}CsC{sub 60} fulleride are studied by synchrotron X-ray powder diffraction as a function of pressure and temperature. In contrast with the behavior of Li{sub 2}CsC{sub 60} shows a phase transition below room temperature from fcc (space group Fm{bar 3}m) to an orientationally ordered primitive cubic phase (space group Pa{bar 3}), isostructural with the metastable phases of Na{sub 2}A{prime}C{sub 60}. Despite the slow cooling protocols adopted, the system shows no other phase transitions even after prolonged standing at 200 K. The pressure dependence of the structure of Li{sub 3}CsC{sub 60} at ambient temperature was followed up to 8.12 GPa. A phase transition occurs at 0.72 GPa to a low symmetry fullerene bridged polymeric phase with short center-to-center interfullerene separations of {approximately}9.38 {angstrom}. This phase was found to be monoclinic (space group P2{sub 1}/a), isostructural with the low-temperature polymer phase of Na{sub 2}RbC{sub 60} and the high-pressure polymer phase of Na{sub 2}CsC{sub 60}. The pressure evolution of the monoclinic lattice constants reveals a highly incompressible, tightly packed, and strongly anisotropic polymeric structure.
- Research Organization:
- Univ. of Sussex (GB)
- OSTI ID:
- 20001162
- Journal Information:
- Chemistry of Materials, Vol. 11, Issue 10; Other Information: PBD: Oct 1999; ISSN 0897-4756
- Country of Publication:
- United States
- Language:
- English
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