Tangled Multi-Walled Carbon Nanotubes

Nanomaterial crystallite and grain size

Administrative data

Endpoint:

nanomaterial crystallite and grain size

Remarks:

Diameters, walls number and length distribution

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study, no GLP compliance

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Internal method ASM.MDA.021 "Characterization of Carbon Nanotubes by transmission electron microscopy"

Principles of method if other than guideline:

The diameters, walls number and length distribution are determined by transmission electron microscopy (TEM).
The beam of electrons that crosses the thin sample allows to create an enlarged image of the object. The main lens is the objective lens that gives an object image (in its image plane) and a diffraction diagram (in its focal place). The other lenses are used for enlarging and projecting this first image or the diffraction diagram onto the observation screen. The point by resolution is 0.27 nm.
The got images are used to know about the appearance of CNT, to achieve diameters and length measurements.

GLP compliance:

not specified

Type of method:

transmission electron microscopy (TEM)

Details on methods and data evaluation:

The different stages from the starting up of the microscope, the complete gun and column alignment, to the particular working modes are described in details in the operating manuals provided by the instruments manufacturer.
A microscopy copper grid covered with a carbon film with holes is plunged into the suspension of MW-CNTs that has been previoulsy prepared in ethanol.
After evaporation of ethanol, the TEM grid is installed on a sample holder and is introduced into the microscope column at the level of the objective lens (an airlock allows the object introduction while keeping a vacuum lower than 10-06Torrs in the microscope column).
One must take care and check that the sample is exactly located at eucentric point, that focusing is well done, or more exceptionnally that the current in one projection lens is good.
The TEM grid can be observed under a 200 kV voltage.
The magnification range is used from 20000 times up to 660000 times according to the wished informations.

A directe images observation on screen is possible thanks to the use of a high-resolution CCD camera (11 Mpixels - model GATAN ORIUS 832). The MW-CNTs appearance (straight, winding...) is qualitatively noticed after several images observation.

When the nanotubes are well defined, statistical measurements of MW-CNTs diameter and length are possible. About twelve images achieved at a magnification level between 220000 to 660000 times are used in order to study about 100 MW-CNTs (inside and outside diameters, lenght). This number of MW-CNTs is useful to obtain a proper representative of a large nanotubes population.
All possible measurements for diameters and length are achieved with the "Digital Micrograph" software of the camera.
The statistical averages for the diameters and the lengths are calculated with the standard deviations. Number histograms can be drawn according to the diameters and the lengths.

The number of walls nwallscan be deduced from the measurements of outer diameters (d[out]) and inner diameters (d[in]) and the distance between two walls. This last one has been evaluated in previous studies realized in the same conditions on about ten measurements of walls spacing and is taken equal to 0.34 nm.
n[walls]= (d[out]-d[in])/2*0.34

Sampling:

MW-CNTs powder (about 10mg) is poured into a vial containing a small volume of ethanol (about 30 ml). The corked vial is placed into an ultrasonic bath (frequency = 35 kHz) during five minutes at ambient temperature in order to disperse them.

Test material

Test material information

Constituent 1

Reference substance name:

GRAPHISTRENGTH C100

IUPAC Name:

GRAPHISTRENGTH C100

Constituent 2

Reference substance name:

Tangled Multi-Walled Carbon Nanotubes

EC Number:

701-160-0

Cas Number:

7782-42-5

Molecular formula:

Hollow tubular carbon, 1-dimensional nano structures with hexagonal arrangement of carbon atoms

IUPAC Name:

Tangled Multi-Walled Carbon Nanotubes

Test material form:

solid: nanoform

Data gathering

Instruments:

Philips - FEI CM200 microscope : LaB6 filament, maximal voltage = 200 kV, point by point resolution = 0.27 nm. The microscope is calibrated with a reference material "Cross-Grating" with a known number of lines per mm.

Results and discussion

Crystallite and grain size

Crystallite and grain size 1

Key result

Mean:

1 097 nm

St. dev.:

906 nm

Remarks on result:

other: Mean length

Remarks:

Measurement of the length distribution

Crystallite and grain size 2

Key result

Mean:

11.7 nm

St. dev.:

3.6 nm

Remarks on result:

other: Mean outer diameter

Remarks:

Measurement of the outer diameter distribution

Crystallite and grain size 3

Key result

Mean:

4.8 nm

St. dev.:

1.7 nm

Remarks on result:

other: Mean inner diameter

Remarks:

Measurement of the inner diameter

Crystallite and grain size 4

Key result

Mean:

10 other: wall(s)

St. dev.:

3 other: wall(s)

Remarks on result:

other: Mean wall number

Remarks:

Measurement of the wall number distribution

Any other information on results incl. tables

Diameters and walls number measurements

The mean values of outer/inner diameters and walls have been calculated based on 100 measurements.

The majority of MW-CNTs (88%) have a diameter comprised between 5 and 15 nm.The D90 for the outer diameter is 16 nm.

	Outer diameter (nm)	Inner diameter(nm)	Walls number(nm)
D90	16	/	/
Mean value Standard deviation	11.7 3.6	4.8 1.7	10 3

The distribution for the outer diameter is in the following table:

Diameter interval (nm)	Number	Accumulated	% number	% accumulated
0-5	0	0	0.0	0.0
10	36	36	36.0	36.0
15	52	88	52.0	88.0
20	8	96	8.0	96.0
25	4	100	4.0	100.0
30	0	100	0.0	100.0
35	0	100	0.0	100.0
40	0	100	0.0	100.0
45	0	100	0.0	100.0
50	0	100	0.0	100.0
55	0	100	0.0	100.0
60	0	100	0.0	100.0
65	0	100	0.0	100.0
70	0	100	0.0	100.0
75	0	100	0.0	100.0
80	0	100	0.0	100.0
85	0	100	0.0	100.0
90	0	100	0.0	100.0
95	0	100	0.0	100.0
100	0	100	0.0	100.0

Length measurements

The MW-CNTs are well dispersed to permit the lengths measurements with Digitalmicrograph Software.

63% of the MW-CNTs have a length between 0 and 1 µm and 90% between 0 and 2 µm.The D90 for the length of MW-CNTs is 2090 nm.

The distribution for the length is in the following table:

Length interval (nm)	Number	Accumulated	% number	% accumulated
0-100	0	0	0.0	0.0
200	1	1	1.0	1.0
300	8	9	7.9	8.9
400	11	20	10.9	19.8
500	6	26	5.9	25.7
600	11	37	10.9	36.6
700	7	44	6.9	43.6
800	3	47	3.0	46.5
900	12	59	11.9	58.4
1000	5	64	5.0	63.4
1100	1	65	1.0	64.4
1200	5	70	5.0	69.3
1300	3	73	3.0	72.3
1400	3	76	3.0	75.2
1500	3	79	3.0	78.2
1600	2	81	2.0	80.2
1700	4	85	4.0	84.2
1800	2	87	2.0	86.1
1900	0	87	0.0	86.1
2000	3	90	3.0	89.1
2100	1	91	1.0	90.1
2200	0	91	0.0	90.1
2300	1	92	1.0	91.1
2400	0	92	0.0	91.1
2500	0	92	0.0	91.1
2600	0	92	0.0	91.1
2700	2	94	2.0	93.1
2800	2	96	2.0	95.0
2900	0	96	0.0	95.0
3000	0	96	0.0	95.0
5000	5	101	5.0	100.0

Applicant's summary and conclusion

Conclusions:

The distribution of outer/inner diameters, length and wall number of a multi-wall carbon nanotubes powder was measured.
The following results were obtained:
Outer diameter: D90=16 nm, mean value= 11.7 nm
Inner diameter: mean value=4.8 nm
Length: D90=2090 nm, mean value=1097 nm
Wall number: mean value: 10.

Executive summary:

The diameters, wall number and length distribution of a MW-CNTs powder have been carried out using a transmission elctron miscroscope (TEM).The D90 for outer diameter and length is 16 nm and 2090 nm respectively. Mean values of 11.7 nm and 4.8 nm were calculated for the outer and inner diameters respectively, a mean length of 1097 nm and a mean number of 10 walls were determined.

These values specifically apply to the tested sample.