Background of Nanocarbons

Osawa Class No. 1

Thurs, May 28, 1:15‐2:05 pm

(28 plates)

2

Overview of nanocarbons

• sp2

– Fullerenes• C60• Higher fullerenes

• Carbon nanotubes

• Multi‐shell fullerenes

– Amorphous

• sp3

– Nanodiamonds

１．Why nanocarbons?

Carbon was the most interesting element in chemistry.Flexibilities in valence, properties and shapes.Extensive applications well anticipated.Surprising discoveries of C60 (1985, 1990) and carbon nanotubes (1991) triggered feverish developmentsWhen will fullerene industry starts?

Indeed, novel forms of fullerenes including carbon nanotubes discovered

and at one time

fullerenes were considered the most promising material for nanotechnology.

Status quo of C60, CNT

• High production cost

• Health hazard possibility

• No outstanding applications found

Year Manuf. methodC60/C70 (80/20)

$/kg

1990

Arc discharge

>1,000,000

1993 100,000

1998 10,000

2001 Combustion 500

Transition of market price of C60/C70 mixture

Our contribution: soot, C60 and carbon nano‐onions are related

Commercial carbon black (pure soot)

Structure of soot was long a matter of dispute.

Furnace black

Rosalind Franklin Prof. S. Ohtani

Crick

Franklin

Wilkinson

Watson

200KeVelectron beam focused within TEMto 150A/cm2

Carbon black（soot）

15 min

spiral

Mostly onions, but・・・

2 nm

Ｓｐｉｒａｌ Ｏｎｉｏｎ

1. Onions are formed from spiral intermediates2. Conversion is reversible and involves self-

adjustment mechanism3. Stable nanao-onions are the final product

+

++

+

C60@C240@C540

C60@C240

C60

C60@C240@C540@C960

Spiro

id-o

nion

inte

rcon

vers

ion

Snow-accreting growth

Groth pathways of the primary particles of soot

13

Overview of nanocarbons

• sp2

– Fullerenes• C60• Higher fullerenes

• Carbon nanotubes

• Multi‐shell fullerenes

– Amorphous

• sp3

– Nanodiamonds

Nanodiamond

• We believe ‘single‐nano diamond’ particles are the final solution to the search of the most useful nanocarbon.

• The first nanocarbon comprised of sp3 carbon atoms. – This statement not rigorously correct.

• Diamond is the best industrial material on earth!

15

Partial list of diamond properties (natural bulk)

classification sub-class values notes

optical TransparencyRefractivity

UV-VIS-IRnD＝2.417

largesthigh

chemicalAcids-alkalis

Oxidation

Not attachedWithstands

supercritical water

inactiveHighly

resistant

electric Dielectric 5.5×1013 Ω・cm insulator

thermal Thermal cond.Specific heat

900-2000 W/m・K0.124 cal/Kg(25C)

largestvery small

materialistic Thermal expan.Young’s modul.

0.8×106/K1,050 GPa

smallestlargest

Major Artificial Diamondsmethod

（raw material）discovery(year)

Form of product（av size）

Country of production

Hydrostatic HPHT

（graphite + Fe + cat）

GE

（1955）Octahedral cubic crystallites（50μm）

China

Shock wave

（explosive, Cu powder + graphite）

DeCarli‐Jamieson

(1961)

Polycrystalline particles (50μm)

China, Japan

Detonation

(TNT+RDX/water)

Danilenko‐Volkov‐

Elin(1963)

Cubic single‐crystal

（4‐5 nm)

Japan

(Russia, China)*

CVD

（CH4 + H2 , C60 + Ar）Eversole(1950)

Polycrystalline films（thickness up to

μm)

[Japan, US] (under developmnt)

*Only agglutinates

17

CH3

NO2O 2N

NO2

NO2O2NN N

N

NO2

TNT

hexogen

CO2 or water

60% diamondsoot

40% amorphouscarbon

1963, Danilenko & Titov (Ukraine)

No carbon source other than carbon atoms in the explosive molecules used.

Yield 3‐5% based on theweight of explosives used.

An ideal material for nanotechnology!

Composition BA military explosive

Discovery of detonation nanodiamond

Stagnation1. First misfortune:

1963-1989 Kept secret in Soviet military regime.

Little progress.2. Second misfortune:

1989-2002 Structure mis-interpreted.

3. First breakthrough:2002 Agglutination recognized and agglutinates broken up into primary particles.

Commercial nanodiamond has been believed dispersed, but actually not.

19

Intensivesonication

No trace of primary particles!

Recognition of agglutinatin by DLS measurements of particle size distribution

SEM

Core agglutinates, 100-200 nm, cannot be disintegrated by any conventional methods.

20

Breakthrough Core agglutinates successfully disintegrated by wet beads‐milling to produce primary crystallites of detonation nanodiamond for the first time (2002).

Beads‐milling:

（１）High‐density beads packed in the milling room to 70‐80% of space.（２）Slurry of substrate particles in water supplied into milling space.（３）The closed mixture agitated at high speed (~4000 rpm).（４）Slurry separated from beads by centrifuge.

Microbeads: 30 μm ZrO2Slurry: 10% agglutinated nanodiamond in water

21

Beads‐Mill in operation at NCRI

Beads: 30μm ZrO2

Mill capacity: 160 mLUltraApex Mill type UAM‐015 Mfd by Kotobuki Ind. Co.,

22

Out‐going slurry

Cooling water

In‐coming slurry

Centrifugal separator

Milling cell in detail

23

Mechanism of beads-milling1. Almost weightless micro-beads

are given high kinetic energy by high-speed rotation.

2. Nano-sized particles pinched between the moving pair of micro-beads receive high impact at the collisional point to be crushed.

Larger by-products

24

Size and shapeTEM of monodisperse particles (re‐aggregated)

Size from three independent determinations : 4.8 ± 0.7 nm

Shape: irregular, most likely truncated octahedra

truncation

Octahedron(shape of natural diamond crystal

Trundcated octahedron(14‐faced)

25

method size, nm source

TEM 4.8±0.8 China

DLS 5.0±0.8 Japan

XRD 4.5±0.5 Russia

Average =

４.8 ± 0.7nm

1. Quite uniform in size.2. Size unchangeable by minor adjustments of

explosion conditions.

Size of SND

26

Stable colloid・・・for a wide range of pH

aggregates Monodisperse aggregates

pH=4.88

27

Core agglutinate (‘UDD’)

Primary particle(mdsn-D)

No. of grains 70,000～350,000 1

Size, nm 60-200 4-5

AqeousSuspension

stable, no precipitates, turbid, grey, no

gellation

stable, no precipitates, transparent colloid,

black, gellation from ca8%

DSC of aq. gel - non-freezing water layer

TGA - Explosive combustion at ca 500°C

Raman - D>>GSEM/TEM visible/assembly Invisible/dispersed

Terminology

(1) Detonation nanodiamond

200nm‐20μm Agglutinate/aggomerate(2) Primary particles of detonation nanodiamond or 5nm diamond particle

4.8±0.7 nmdispersed only in colloidal solution

aggregated in dried solid