Carbon Nanotube Refer

Materials and Characteriz

Jeffrey A. Fagan

National Institute of Standards and Technology

Gaithersburg, MD
Nanotube Market

C

E

Chemical & Engineering NewsCarbon Nanotubes By The Metric TonNovember 12, 2007, Volume 85 (46), pp. 29-35
• Lack of purified materials for general aud

• Many comparables – no common sample• NanoEHS uncertainties

Market Problem

C

E
(n,0)

zigzag

(n,n)

armchair

(n,m) chiral

Single-Wall Carbon Nanotubes

Roll up vector determines physical pro

electronic nature and surface intera
Single-Wall Carbon Nanotubes

Roll up vector determines physical pro

electronic nature and surface intera
Only 163 of the 300 – 400 

viable possibilities are shown

From Hersam, M. Natu

Green: Metallic, Pink, Purple: Se

Hundreds of stable 

nanotubes

Synthetic methods 

generate multiple tubes 

with different properties

All tube types potentially 

useful

Polydispersity Problem
Polydispersity Problem

ALL SAMPLES 

are DIFFERENT

SWCNT length 

distribution, powder 

morphology, 

impurity content all 

vary batch to batch 

(or even within a 

batch) and across 

manufacturers.
Nanotube Metrology Progra

Reference

MaterialsStandard

Measurement

Protocols

Round Robins

EHS assessments &

selected applications

Intrinsic property

measurements

Separation and

fractionation

Dispersion C

Liquid Phase So
Nanotube Metrology Progra

Reference

MaterialsStandard

Measurement

Protocols

Round Robins

EHS assessments &

selected applications

Intrinsic property

measurements

Separation and

fractionation

Dispersion C

Liquid Phase So

S

C
Raw Soot (Candidate SRM 248

Photograph and SEM microg

Techniques in collaboration withAnalytical Chem. (R. Zeisler, R. Spatz, L. Yu etc...)Materials Reliability (E. Mansfield, S. Hooker)Stat. Eng. Div. (S. Leigh)
• ≈ 0.26 g lots 

• Certified for elemental 

composition.

• Informational Values

– Diameter distribution– Raman spectra– Processing Data

Raw Soot (Candidate SRM 248

Photograph and SEM microg
SRM 2483

Courtesy of Michael Postek, NIST (MEL)High-angle backscattered electron image of the same field as the previous figure. Note the bright metal catalytic particles. (Field of view = 1280 nm).

Transmitted electron image nelectron density particles (dathe bright particles of the preof view = 1280 nm)
TGA Analysis of CNT Materials

Monitors the weight 

remaining as a function of temperature

~ 5 mg of material heated at 

10 °C/min to 800 °C in flowing air and ceramic pans 

M

• 3 samples per RM vial

– Vials stored in dessicator before and after 

sampling

SRM 2483
Reference Material Consist

Residu6.540%(0.2114Residu6.715%(0.2262

Residu6.905%(0.261

480.53°C479.00°C

480.21°C

0

20406080

100

Weight (%)

0 200 400 600 

Temperature (°C)

 SRM2483––––––– SRM2483– – – – SRM2483––––– ·

• Oxidation temperature 

(°C)

– 482.2 ± 1.2

• Residual Mass (%)

– 7.09 ± 0.33
SRM 2483

Residual catalyst 

concentrations measured by 

instrumental neutron activation 

analysis (INAA) and cold 

neutron prompt gamma-ray 

activation analysis (CNPGAA)
Activation analysis re

Activation analysis re

SRM 2483 (INAA & PGAA) (INAA & PGAA)

Water 

5.18 ± 0.32 

Additional info

available for R

absorbance, c
Dispersion
Dispersion

Deoxycholate

1 hour So

at ≈ 1 W 

in 2 % mass/v

2 h Centri

at ≈ 40 

Supern

• Purified Soot (RM 8282).

• Information on elemental 

composition.

– TGA– Neutron Methods

• Informational Values

– Diameter distribution– Raman spectra– Microscopy

Purified Buckypaper RM

Representative Photograph 

of SWCN
Carbon Nanotubes:

D

L

After dispersion, the individualized SWCNTs have 

uniform diameter, but a vast length distribu
Centrifugation Based Length Separation

With correct set up the n

will be length dependen

tubes moving fa

( ) ( )

0

3

0

4

2

6

2

,

+

−

+

≈

γ

γ

η

ρ

ρ

G

r

N

c s SWCNT i

i i l

We can take advantage 

dependence of the frict

for a rod to enable leng
• Specified average lengths

– ~ 0.8 

μ

m

– ~ 0.4 

μ

m

– ~ 0.15 

μ

m

• Informational Values

– Diameter distribution– Raman spectra– Processing Data

Length Populations RM 8281

Photograph of length separate

nanotubes dispersed in sur

Summary:

• To address the metrology needs for nanotube

working on releasing SWCNT reference mat

• SRM 2483: Raw Nanotube Soot

• RM 8282: Purified Nanotube Bucky Pap

• RM 8281 Length sorted nanotubes in aqueous 

• A workshop on chirality measurement, separa

applications will be held at NIST in Septem
Acknowledgments:

Questions?

Contact: jeffrey.fagan@nist.gov