Fullerites

Prassides K, Kroto FI W, Taylor R, Walton D R M, David W I F, Tomkinson J, Fladdon R C, Rosseinsky M J and Murphy D W 1992 Fullerenes and fullerites in the solid state neutron soattering studies Carbon 8 1277-86... 

Chemists were greatly surprised when soccer-ball-shaped carbon molecules were first identified in 1985, particularly because they might be even more abundant than graphite and diamond The C60 molecule (10) is named buckminsterfullerene after the American architect R. Buckminster Fuller, whose geodesic domes it resembles. Within 2 years, scientists had succeeded in making crystals of buckminsterfullerene the solid samples are called fullerite (Fig. 14.32). The discovery of this molecule and others with similar structures, such as C70, opened up the prospect of a whole new field of chemistry. For instance, the interior of a C60 molecule is big enough to hold an atom of another element, and chemists are now busily preparing a whole new periodic table of these shrink-wrapped atoms. 

FIGURE 14.32 These small crystals are fullerite, in which buckminsterfullerene molecules are packed together in a close-packed lattice. 

Saito S, Umemoto K, Miyake T (2004) Electronic Structure and Energetics of Fullerites, Fullerides, and Fullerene Polymers 109 41-57 Sakata M, see TakataM (2004) 109 59-84... 

Blank VD, Nuzdin AA, Bagramov RK, Prokhorov VM (2001) A comparison of some thermodynamic parameters between superhard fullerite, some metals and some covalent elements. Carbon 39 905-908. 

Fullerenes are the third natural form of carbon. These have been found to exist in interstellar dust and in geological formations on Earth, but only in 1985 did Smalley, Kroto and co-workers discovered this class of carbon solids and their unusual properties [447, 448]. It has been shown that Ceo, the most common fullerene, could be transformed under high pressure into the other forms of carbon, diamond, and graphite [449] or, at moderately high pressures and temperatures, into new various metastable forms [450 53]. Ceo crystals, fullerites, have/cc structure with weak van der Waals interactions. This structure is stable at ambient temperature up to 20 GPa and at ambient pressure up to 1800 K [454, 455]. 

Polymerization of fullerite was first obtained at ambient pressure by means of sample irradiation [456]. Visible or UV light leads molecules to link together in a covalently bonded fee structure. From x-ray diffraction data a 2 + 2 cycloaddition mechanism was proposed in which the van der Waals interactions are replaced by single covalent bonds between adjacent Ceo molecules [456]. More recent results indicate that linear chains with two square rings per molecule or branched chains with three square rings per molecule are obtained... 

Reactivity of fullerite powder under shock compression has been investigated in the 10- to 110-GPa pressure range [470], and recovered samples of multiple... 

Two other forms of CNTs are recognized. The fullerite is a highly incompressible form with a diamondlike hardness. The torus is a donut-shaped nanotube. These circular nanotubes have extremely high magnetic moments and outstanding thermal stability. The particular properties are dependent on the radius of the tube. 

Graphite and diamond are network solids that are insoluble in all liquid solvents except some liquid metals. Flowever, the fullerenes, which are molecular, can be dissolved by suitable solvents (such as benzene) buckminsterfullerene itself forms a red-brown solution. Fullerite currently has few uses, but some of the compounds of the fullerenes have great promise. For example, K3C60 is a superconductor below 18 K, and other compounds appear to be active against cancer and diseases such as AIDS. 

Direct catalyzed hydrogenation of crystalline fullerite or fullerenes in solution. 

Summarizing this section, the main parameters which control reaction of solid fullerite with hydrogen gas are temperature, H2 pressure and duration of treatment. However, some additional parameters also need to be taken into account. For example, our own experience and also reports from other researchers show... 

IR transmission spectra (T) of the thin polycrystalline specimens or powders were measured using IR microscope of the Fourier-spectrometer at room temperature in the spectral range of 600 5,000 cm-1. Optical absorption spectra were calculated as -ln(T). Figure 11.11 demonstrates normalized absorption spectra of fulleranes C60Hx with x = 36, 42, 48 and 60 together with the well known spectrum of fullerit... 

Fig. 11.11 Normalized absorption spectra of fullerit C60 and fulleranes C6QHx with x = 36, 42, 48 and 60, T = 300 K...

Goeres, A. Sedlmayr, E. 1991 On the nucleation mechanism of effective fullerite condensation. Chem. Phys. Lett. 184, 310-317. 

Small carbon grains are assumed to be the carrier of the prominent interstellar ultra violet absorption at 217 nm. To investigate this hypothesis, we produced small carbon particles by evaporating graphite in an inert quenching gas atmosphere, collected the grains on substrates, and measured their optical spectra. In the course of this work - which in the decisive final phase was carried out with the help of K. Fostiropoulos and L. D. Lamb - we showed that the smoke samples contained substantial quantities of C60. The fullerene C60 (with small admixtures of C70) was successfully separated from the sooty particles and, for the first time, characterized as a solid. We suggested the name fullerite for this new form of crystalline carbon. 

Kratschmer, W. Fostiropoulos, K. 1992 Fullerite - Neue Modifikationen des Kohlenstoffs. Physilc Zeit. 23, 105-110. 

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