Doped graphites

Chemical erosion can be suppressed by doping with substitutional elements such as boron. This is demonstrated in Fig. 14 [47] which shows data for undoped pyrolitic graphite and several grades of boron doped graphite. The mechanism responsible for this suppression may include the reduced chemical activity of the boronized material, as demonstrated by the increased oxidation resistance of B doped carbons [48] or the suppressed diffusion caused by the interstitial trapping at boron sites. 

Fig. 14. Chemical yield as a function of temperature for boron doped graphites.

Highly oriented pyrolitic graphite Glassy carbon -Pyrocarbon Graphite monocrystal Doped graphite (C,6 AsF5 )... 

Figure 5.9 GALDI mass spectrum of natural rubber (from toluene/THF solution) on silver doped graphite matrix. The signal spacing of 68 Da corresponds to the isoprene monomer...

Arc discharge [25] is initially used for producing C60 fullerenes. Nanotubes are produced by arc vaporization of two carbon rods placed in a chamber that is filled with low pressure inert gas (helium, argon). The composition of the graphite anode determines the type of CNTs produced. A pure graphite anode produce preferably MWNT while catalyst (Fe, Co, Ni, Y or Mo) doped graphite anode produces mainly SWNT. This technique normally produces a complex mixture of components, and requires further purification to separate the CNTs from the soot and the residual catalytic metals present in the crude product. 

Bindra, C. Nalimova, V. A., and J. E. Fischer. 1998. In-plane structure and thermal (in)stability of LiC218 based on boron-doped graphite. Mol. Cryst. Liq. Cryst. 310 19-25. 

Yagi, M., R. Saito, T. Kimura, G. Dresselhaus, and M. S. Dresselhaus. 1999. Electronic states in heavily Li-doped graphite nanoclusters. J. Mater. Res. 14 3799-3804. 

Solar furnace Solar rays focused on a metal doped graphite target. Growth dynamics similar to PLV 1.4 Good quality CNTs, little amorphous carbon. Spreading not expected in the near furture... 

The development of low erosion doped graphites has reached a point where chemical erosion at elevated temperatures can be suppressed. The important parameter appears to be the atomic distribution of metal carbide dopants. The future development must go in the direction of the production of doped bulk CFC materials. 

Fig. 10.3. TDS measurements of D retention in (a) pure graphites, and (b) doped graphites as a function of D+ fluence [17]...

A.A. Haasz, J.W. Davis, Deuterium retention in doped graphites, J. Nucl. Mater. 232 (1996) 219... 

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