Fullerene Intercalation Compounds

M. Pouchard, C. Cros, P. Hagenmuller et al., A brief overview on low sodium content silicides are they mainly clathrates, fullerenes, intercalation compounds or Zintl phases Solid State Sci. 4, 723-729 (2002)... 

Graphite in contact with liquid potassium, rubidium or caesium at 300°C gives intercalation compounds (CgM) which ignite in air and may react explosively with water [1], Fullerene black —probably a finely divided and distorted graphite — impregnated with potassium explodes spontaneously in air [2],... 

It is very likely that PF6 occupies the Van de Waals gap between the SWNTs in a similar way than in graphite intercalation compounds [6] and in anion-doped fullerenes [7]. Because of lower surface area between... 

Molybdenum(VI) fluoride will insert into graphite to give8,29 nominal C5MoF6 and other compositions, and with fullerene C60 it forms30 an intercalation compound in which some oxidation process has occurred since the molybdenum exists as a molybdenum(V) fluoride species. 

Research in graphite intercalates has paved the way for significant current interest in intercalation compounds of the fullerenes (Box 7.1) and carbon nanotubes, which represent wrapped up versions of graphite sheets. Graphite intercalation compounds have been prepared with intercalated fullerenes and nanotubes. We will return to carbon nanotube chemistry in Chapter 15. 

To close this section on trimetal nitride endohedral fullerenes, we present and discuss data from potassium intercalation experiments on Sc3N C80. As was the case for Kx(Tm C82), x-ray photoemission measurements of the K 2p and C Is signals can be used to give a good indication of the overall potassium concentration in such intercalation compounds. Figure 16 displays the K 2p photoemission lines for several intercalation levels in Kx(Sc3N C80). 

NEW ALLOTROPES OF CARBON GRAPHITE INTERCALATION COMPOUNDS, FULLERENES, FULLEROIDS, CARBON NANOTUBES, PEAPODS, AND GRAPHENE... 

Intercalation compounds of alkali metals. These contain alkali metal ions occupying interstitial sites between fullerene clusters. 

We report results of first-principles molecular orbital calculations on model clusters of graphite (C24), alkali graphite intercalation compounds (MC48 M = Li, Na, K, Rb, Cs), fullerene (Ceo), and fluorinated fullerenes (CeoFa, x — 18, 36, 48). The calculated partial densities of states (pDOS) are compared with measured x-ray absorption near edge structure (XANES) spectra, x-ray photoelectron spectra (XPS), x-ray emission spectra (XES), and ultraviolet photoelectron spectra (UPS). In the case of graphite and its compounds, the calculated pDOS well reproduce features of the observed XANES and UPS spectra. The calculated pDOS and the observed XPS, UPS and XANES of CeoFx (x = 0, 36, 48) are also in satisfactory accordance. 

Carbon atoms crystallize in several forms. Graphite and diamond are well known carbon polymorphs. Fullerenes, which were discovered in the 1980 s, have also been well characterized. Carbon materials show a variety of different physical and chemical properties. Because of this the electronic structure of carbon materials has been investigated using a number of different experimental techniques, for example, XPS, UPS and XANES. Theoretical studies of carbon materials have been also performed. However, experimentally observed spectra are not always consistent with theoretical predictions. Recently, in order to understand the various kinds of observed electronic spectra, DV-Xa calculations have been performed on a small cluster model. [1] In the present paper, we report results of DV-Xa calculations performed on the carbon materials graphite, alkali graphite intercalation compounds (GIC), fullerene, and fluorinated fullerenes. 

Fullerenes possess a distinct ability to form intercalation compounds with other substances, especially with solvents. From benzene for instance, Qo crystallizes as a compound Ca)-4 (C Hg). Similar crystaUizations are known for further solvents like cyclohexane or CCI4. 

Measurements on graphite intercalation compounds (GICs), fullerene compounds, nanotubes, and related materials Studies of lithium/carbon-containing ceramics derived from pyrolysis of organic polymer precursors... 

Measurements on graphite intercalation compounds (GlCs), fullerene compounds, and other materials... 

In general intercalation compounds often show interesting properties as electronic conductors. That is also the case of the products of the intercalation of alkali metals in buckminsterfullerene. As discussed above, this process results in an electron transfer from guest to host thus giving rise to fulleride anions. Such a charge transfer is fundamentally due to the large electron affinity and low reduction potential that characterize the fullerenes. 

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