ELECTRICAL RESISTIVITY OF GRAPHITE MATERIALS

L. I. Berger

At normal conditions, the only stable crystallographic modifi-

cation of carbon is graphite. The quasi-stable diamond turns into
graphite starting from about 1000ºC in the air. In industry, a gra-
phitic material is commonly called either carbon, if it consists of
small and low-oriented crystallites, or graphite, the material with
highly ordered structure. In the 1970s, the first carbon filaments
of about 7 nm in diameter were grown by Morinobu Endo at the
University of Orleans, France, by the vapor-growth technique.
In 1985, Sir Harold Walter Kroto of Sussex University, UK, and
Richard E. Smalley and co-workers at Rice University discovered
spherical carbon molecules, C

60

(or C60), consisting of combina-

tions of carbon atoms organized into hexagons and pentagons,
named buckminsterfullerenes or fullerenes and possessing very
promising mechanical and electrical properties. In 1991, Sumio
Iijima, NEC Labs, Japan, and David S. Bethune, IBM Almaden
Labs, observed the carbon atomic groups in the form of tubes
capped by halves of the fullerene molecules and formed on the
cathodes of carbon arc devices. The length of the tubes could be
up to tens of micrometers and the diameter, naturally, is equal
to that of the fullerene molecule. These tubes, called nanotubes,
may be single wall (SWNT) or consist of several concentric tubes
with a common axis (multi-walled nanotubes, MWNT). Two-di-
mensional graphene is another crystallographic modification of

graphite (Saroj Nayak, Rensselaer U., 2004) that is a flat hexagonal
network of carbon atoms with a thickness equal to the carbon
atom size. The nanotube may be considered as formed by strips
of graphenes turned into a cylinder. The character of the electrical
conductivity (metallic or semiconductive) of a SWNT depends
on orientation of the carbon hexagons of the nanotube surface
regarding its axis (the chiral angle [Ref. 1]). The following table
contains some typical data on electrical and electronic properties
of graphite materials.

References

1. M. S. Dresselhaus, G. Dresselhaus, and Ph. Avouris (Eds.), Carbon

Nanotubes. Synthesis, Structure, Properties, and Applications,
Springer-Verlag, 2001.

2. ESPI Metals Catalog, 2007.
3. SPI Supplies Catalog, 2007.
4. F. L. Vogel, J. Mater. Sci., 12, 982–986, 1977.
5. K. S. Novoselov et al., Nature, 438, 197–200, 2005.
6. Y. Zhang et al., Nature, 438, 201–204, 2005.
7. N. Tombros et al., Nature, 448, 571–574, 2007.
8. H. Dai, in Ref. 1, pp. 29–53.
9. CTI Carbon Nanotube Cat., 2007.
10. L. Matija et al., Sci. Forum, 413, 49–52, 2003.

Material

Electrical resistivity ρ at R. T.

mΩ cm [μΩ inch]

Energy gap at R. T.

eV

Electron mobility

cm

2

/V s

(1/ρ)dρ/dt near R. T.

10

–4

°C

–1

Ref.

Bulk graphite

Electromet graphite

1.90 [750]

–5

2

Electro graphite

1.60 [630]

–5

2

Aeromet graphite

1.47 [580]

–5

2

ESPI Superconductive

1.75 [690]

–5

2

Radioelectronics data

30 [11,800]

–5.6

3

Highly ordered pyrolytic graphite

Parallel 0.04 [15.7]

3

Across 150 [59000]

Single crystal graphite, normal to c-axis

1•10

-6

4

Graphenes

n-Graphene

≈5 (М); ≈10 (Г)

c

10

6

5,6

p-Graphene

10

4

7

Carbon nanotubes

Metallic SWNT

12 kΩ

a

1

Semiconducting SWNT

0.7 – 0.9

b

128

d

1

MWNT

10

2

9

Carbon fullerenes

Fullerene (C

60

)

10

12

1.95

10

a

Minimum resistance of individual nanotubes [Ref. 8]

b

Est. from Ref. 1, p. 47

c

Est. from Ref. 1, p. 116

d

Est. from Ref. 1, p. 179.

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