Pierson Hugh O. Handbook of carbon, graphite, diamond and fullerene. New Jersey / carbon

6

Carbon, Graphite,

Diamond,

and Fullerenes

Table

1.2. Major Processes for the

Production of Carbon

Materials

Process

Carbon

Product

Molding/carbonization

Molded

graphite

Vitreous

carbon

Pyrolysis/combustion

Lampblack

Carbon

black

Extrusion/carbonization

Carbon

fiber

High-pressure/shock

Diamond

Chemical Vapor

Deposition

Polycrystalline

diamond

Pyrolytic

graphite

Sputtering/plasma

Diamond-like carbon (DLC)

The

wide

variety

of

carbon-derived

materials

is

reflected

in

the

diversity

of

the

industry,

from

small

research

laboratories

developing

diamond

coatings

to

very

large

plants

producing

graphite

electrodes.

Together,

these

organizations

form one

of the world’s

major

industries.

However,

black

art and

secrecy

still

prevail

in

many

sectors

and

progress

often

seems

to

occur

independently

with little

interaction

and

coordination

when

actually

the

various

technologies

share

the

same

scientific

basis,

the same

principles,

the same chemistry,

and in many

cases

the same

equipment.

A

purpose

and

focus

of this

book

is to

bring

these

divergent

areas

together

in one unified

whole

and to accomplish,

in a book

form,

what

has

been

the

goal

for

many

years

of several

academic

groups

such

as the

Pennsylvania

State

University.

Yet

progress

is undeniable.

The technology

is versatile

and dynamic

and the scope of its applications

is constantly

expanding.

It is significant

that

three

of the

most

important

discoveries

in the

field

of materials

in the

last

thirty

years

are

related

to

carbon:

carbon

fibers,

low-pressure

diamond

synthesis,

and,

very

recently,

the

fullerene

molecules.

The

market

for carbon-derived

products

is

divided

into

two

major

categories:

carbon/graphite

products

and

diamond

with global

markets

of

$5.5 billion

and $7.5

billion

respectively.

These and the following

figures

are

based

on

U.S. Government

statistics

and

other

sources

and

are

to

be

regarded

as

broad

estimates.t5j

Additional

details

on

the

market

will

be

given

in the

relevant

chapters.

Market

for

Carbon

and

Graphite

Products.

Table

1.3

lists

the

estimated

markets

for

the

various

forms

of carbon

and

graphite

reviewed

in Chs.

5 to 10. The

old and well-established

industry

of molded carbon and

graphite

still

has a major share

of the

market

but the

market

for others

such

as carbon

fibers

is expanding

rapidly.

Table

1.3.

Estimated

World

Market for Carbon

and Graphite

Products

in 1991

3

million

Molded

carbon

and

graphite

3740

Polymeric

carbon,

vitreous

carbon

and

foam

30

Pyrolytic

graphite

30

Carbon

fibers

200

Carbon

fiber composites

700

Carbon

and

graphite

particles

and

powders

800

Total

5500

Market

for Diamond

Products.

Table

1.4 gives an

estimate

of the

market for the various

categories

of diamond.

Gemstones,

with

over

90% of the

market, still

remain

the

major

use of

diamond

from

a monetary

standpoint,

in a business

tightly

controlled

by a

worldwide

cartel

dominated

by the

de Beers

Organization

of South

Africa.

The

industrial

diamond market

is

divided

between

natural

and

high-

pressure

synthetic

diamond, the latter

having

the larger

share of the market.

This

market

includes

coatings

of CVD

diamond and

diamond-like

carbon

(DLC) which

have a small

but

rapidly-growing

share.

$

million

Gemstones

7000

industrial

diamonds

500

Total

7500

7.0

GLOSSARY

AND

METRIC

CONVERSION

GUIDE

A

glossary

at the end of the book

defines

terms which

may

not

be

familiar

to some

readers.

These

terms are printed

in italics in the

text.

All

units in this

book

are metric and follow the

International

System

of

Units

(SI). Forthe

readers morefamiliarwith

the English and other common

units,

a metric conversion

guide

is found

at the

end of the book.

The

following is a partial list

of the most important references,

periodicals,

and conferences dealing

with carbon.

Chemistry

and

Physics

of

Carbon

ChemistryandPhysics

ofCarbon,

(P. L. Walker, Jr. and P. Thrower,

eds.),

Marcel Dekker, New York (1968)

Cotton,

F. A. and Wilkinson,

G., AdvancedlnorganicChemistry,

Interscience

Publishers, New York

(1972)

Eggers,

D. F.,

Gregory,

N. W.,

Halsey,

G. D., Jr. and Rabinovitch,

B. S.,

Physical

Chemistry,

John

Wiley & Sons, New

York

(1964)

Huheey,

J. E., inorganic

Chemistry,

Third

Edition, Harper & Row,

New York

(1983)

Jenkins,

G. M. and Kawamura,

K., PolymericCarbons,

Cambridge

University

Press,

Cambridge,

UK (1976)

Introduction

9

Mantell,

C. L.,

Carbon

and

Graphite

Handbook,

Interscience,

New

York

(1968)

Van Vlack,

L. H., Elements of Materials

Science

and Engineering,

4th

ed.,

Addison-Wesley

Publishing

Co.,

Reading

MA

(1980)

Wehr, M. R., Richards,

J. A.,

Jr.,

and

Adair, T. W., Ill, Physics of theAtom,

Addison-Wesley

Publishing

Co.,

Reading,

MA

(1978)

Carbon

Fibers

Donnet,

J-B. and Bansal, R. C.,

Carbon

Fibers, Marcel

Dekker

Inc.,

New

York

(1984)

Carbon Fibers Filaments and Composites (J. L. Figueiredo,

et

al., eds.),

Kluwer

Academic

Publishers, The

Netherlands

(1989)

Dresselhaus,

M. S., Dresselhaus,

G.,

Sugihara,

K.,

Spain,

I.

L.,

and

Goldberg,

H. A.,

Graphite

Fibers

and Filaments,

Springer

Verlag,

Berlin

(1988)

Diamond

Applications of Diamond Films and Related Materials (Y. Tzeng,

et al., eds.) ,

Elsevier

Science

Publishers, 623-633 (1991)

Davies,

G.,

Diamond, Adams

Hilger

Ltd.,

Bristol

UK

(1984)

The Properties

of Diamond

(J. E. Field,

ed.), 473-499,

Academic

Press,

London

(1979)

Applied

Physics

Letters

Carbon

Ceramic

Bulletin

Ceramic

Engineering

and Science

Proceedings

Diamond

and

Related

Materials (Japan)

Diamond

Thin

Films

(Elsevier)

Japanese Journal

of Applied Physics

Journal

of the

American Ceramic

Society

10

Carbon,

Graphite,

Diamond, and

Fullerenes

.

Journal

of the American Chemical

Society

.

Journal

of Applied

Physics

n

Journal

of Crystal Growth

n

Journal

of Materials

Research

•

Journal

of Vacuum

Science

and Technology

.

Materials

Engineering

.

Materials

Research

Society

Bulletin

n

Nature

n

SAMPE

Journal

.

SAMPE

Quarterly

.

Science

.

SPIE

Publications

.

Tanso

(Tokyo)

.

Carbon

Conference

(biennial)

.

International

Conference

on Chemical

Vapor Deposition

(CVD) of

the

Electrochemical

Society (biennial)

. Composites

and Advanced

Ceramics

Conference

of the

American

Ce-

ramic Society

(annual)

.

Materials

Research

Society

Conference

(annual)

REFERENCES

1.

Krauskopf,

K. B., lnfroducfion

to

Geochemistry

McGraw-Hill

Book

Co.,

New

York

(1967)

2.

Chart

ofthe Atoms, Sargent-Welch

Scientific Co.,

Skokie, IL (1982)

3.

Hare, J. P. and Kroto,

H. W.,

A

Postbuckminsterfullerene

View of

Carbon

in the

Galaxy,

Act. Chem. Res., 25106-I

12 (1992)

4.

Davies, G., Diamond, Adam Hilger

Ltd., Bristol,

UK

(1984)

5.

Data

Bank, G.A.M.I.,

Gorham,

ME

(1992)

The

Element

Carbon

13

In order

to

understand

the

formation

of the allotropes

of carbon

from

these

precursors

and the

reasons

for

their

behavior

and

properties,

it

is

essential

to have

a clear

picture

of the

atomic configuration

of the

carbon

atom and the various

ways

in which

it bonds

to other

carbon

atoms.

These

are

reviewed

in this

chapter.

1.2

The

Structure

of the

Carbon

Atom

All atoms have a positively

charged

nucleus composed

of one or more

protons,

each

with

a positive

electrical

charge

of +l,and neutrons

which

are

electrically

neutral.

Each

proton

and

neutron

has

a

mass

of

one

and

together

account

for

practically

the

entire

mass

of the

atom.

The

nucleus

is

surrounded

by

electrons,

moving

around

the

nucleus,

each

with

a

negative electrical charge of -1.

The

number

of electrons

is the same as the

number

of protons

so that the

positive

charge

of the

nucleus

is balanced

by

the

negative

charge

of the

electrons

and

the atom

is electrically

neutral.

As

determined

by Schroedinger,

the

behavior

of the

electrons

in their

movement

around

the nucleus

is governed

by the specific

rules

of standing

waves.t3]

These

rules

state

that,

in any

given

atom,

the

electrons

arefound

in a series

of energy

levels

called

orbitals,

which

are distributed

around

the

nucleus.

These

orbitals are well defined

and, in-between

them,

large

ranges

of

intermediate

energy

levels

are

not

available

(or

forbidden)

to

the

electrons

since

the

corresponding

frequencies

do

not

allow

a

standing

wave.

In any orbital,

no more than two electrons

can

be

present

and these

must have

opposite

spins

as stated

in the Pauli’s

exclusionprinciple.

A more

detailed

description

of the general

structure

of the

atom

is given

in Ref. 3,

4, and

5.

Nucleus

and

Electron

Configuration

of the

Carbon

Atom.

The

element

carbon

has the symbol C and an atomic

number

(or 2 number)

of 6,

i.e., the

neutral

atom

has six protons

in the

nucleus

and

correspondingly

six

electrons.

In addition,

the

nucleus

includes six

neutrons

(for the carbon-12

isotope,

as reviewed

in Sec. 2.0 below).

The

electron

configuration,

that is, the

arrangement

of the electrons

in each orbital,

is described

as: 1s* 2s2 2p2. This

configuration

is compared

to that

of neighboring

atoms in Table

2.2.

The

notation

ls*

refers

to

the

three

quantum

numbers

necessary

to

define

an

orbital,

the

number

“1”referring

to the K or first

shell

(principal

quantum

number).

The letter

“s”refers

to the sub-shell

s (angularmomen-

14

Carbon,

Graphite,

Diamond,

and Fullerenes

turn quantum

number)

and the superscript

numeral

“2”refers

to the number

of atoms

in that

sub-shell.

There

is only

one

orbital

(the

s orbital)

in the K

shell

which

can

never have

more than

two electrons.

These

two

electrons,

which

have

opposite

spin,

are the closest

to the nucleus and have the lowest

possible

energy.

The filled

K shell

is completely stable

and its two electrons

do not take

part

in any

bonding.

Table

2.2.

Electron

Configuration

of Carbon

and

Other

Atoms

Shell

Element

K

L

M

First

Ionization

Symbol

Z

Is

2s

2p

3s

3p

3d

Potential

(eV)

H

1

1

13.60

He

2

2

24.59

Li

3

2

1

5.39

Be

4

2

2

9.32

B

5

2

2

1

8.30

C

6

2

2

2

11.26

N

7

2

2

3

14.53

0

8

2

2

4

13.62

F

9

2

2

5

17.42

Ne

10

2

2

6

21.56

Na

11

2

2

6

1

5.14

Etc.

Note: The

elements

shown

in bold (H, N and

0)

are those which

combine

with

carbon

to form

most

organic

compounds.

The

next

two

terms,

2s2 and

2p*l refer

to the

four

electrons

in the L

shell.

The

L shell,

when filled, can never have more

than eight

electrons.

The

element

neon

has

a filled

L shell.

The L-shell

electrons

belong

to two

different

subshells,

the

s and

the

p, and

the

2s and the

2p

electrons

have

different

energy

levels

(the number“2”referring

to the

Lorsecond

shell, and

the letters “s”and “p”tothe orbitals

or sub-she//s).

Thetwo

2s electrons

have

opposite

spin

and the two

2p electrons

parallel

spin.

Thisview

of the carbon

atom

is represented

schematically

in Fig. 2.1.

The

Element

Carbon

15

The

configuration

of the

carbon atom

described

above

refers

to the

configuration

in its ground

state, that is, the state where its electrons

are in

their

minimum

orbits, as close to the nucleus

as they

can be, with their

lowest

energy level.

Nucleus

L Shell

6

Protons

6

Neutrons

(Carbon-12)

K Shell

L Shell

Electrons

Electrons

1s

2s

2P,

2Py

2P2

11

t1

1

1

Two

half-filled

2p orbitals

I

I