Fullerides doped

Gunnarsson O, Han JE, Koch E, Crespi VH (2005) Superconductivity in Alkali-Doped Fullerides 114 71-101... 

This direct method is a convenient route, especially for saturation-doped fullerides MgCgo-A facile control of the alkali metal fulleride stoichiometry of M Cgg (M = K,... 

Figure 7.31 Variation of with the cubic lattice parameter in doped fullerides.

Fig. 19 Estimate of the critical ratio U/W for a multiband Hubbard model describing the doped fullerides. For this calculation, the structure remains the same (disordered fee) for the metal-insulator transition when the degeneracy is taken into account. (From [46])...

The tiu configuration was also explored in the fullerene anions Ceo - For this system the orbital disproportionation (see Sect. 5) was first revealed by Ceulemans, Chibotaru, and Cimpoesu [25,26] by direct estimation of the electron interactions in the distorted configuration in order to explain the origin of conductivity in the alkaline-doped fullerides A3C60. 

O. Gunnarsson, Alkali-Doped Fullerides Narrow-Band Solids with Unusual Properties (World Scientific, Singapore, 2004)... 

R288 L. Cristofolini and M. P. Fontana, Vibrational Properties and Phase Transitions in Lithium Doped Fullerides , Asian J. Phys., 2000,9, 609 R289 T. A. Cross and J. R. Quine, Protein Structure in Anisotropic Environments Development of Orientational Constraints , Concepts Magn. Reson., 2000,12, 55... 

Ceo is ti = 1.034 nm = 10.34 A). The lattice constant of the FCC crystal composed ofCeo units is 14.16 A,just3% smaller than the value 14.62A, which is what we would expect for incompressible spheres in contact with their nearest neighbors. The free space between such spheres is enough to accommodate other atoms. In fact, structures in which this space is occupied by alkali atoms (Li, Na, K, Rb and Cs) have proven quite remarkable they exhibit superconductivity at relatively high transition temperatures (see Table 13.1). The positions occupied by the alkali atoms are the eight tetrahedral and four octahedral sites of the cubic cell, shown in Fig. 13.7. When all these sites are occupied by alkali atoms the structure has the composition M3C60. Solids with one, two, four and six alkali atoms per Ceo have also been observed but they correspond to structures with lower symmetry or to close-packed structures of a different type (like the BCC crystal). All these crystals are collectively referred to as doped fullerides . 

The mechanism of superconductivity in doped fullerides is not perfectly clear, because the presence of extra electrons on each Ceo unit introduces complications to electron correlations. This has motivated theoretical studies based on the Hubbard model, in addition to models based on electron-phonon interactions. In... 

Maruyama, Y, Inabe, T, Ogata, H., Achiba, Y, Suzuki, S., Kikuchi, K., and Ikemoto, 1., Observation of metallic conductivity and sharp superconductivity transition at 19 K in K-doped fulleride Cg) single crystal, Chem. Lett., 1849, 1991. 

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