Satellite Workshop - MSIN10
4th International Workshop on Metrology, Standardization and Industrial Quality of Nanotubes
27 June 2010, Montreal, CanadaIntroduction / Scope / Themes
Carbon nanotube science is currently maturing into a technology for real world applications and as such is leading us into previously uncharted territory in nanotechnology. Commercial adoption of a material requires a level of consistency and quality that can only be assured by internationally agreed upon standards of measurement. The research community also benefits from standard measurement practices and quality in the carbon nanotube supply system as it facilitates interlaboratory comparisons of research results. The annual MSIN workshop strives to bring together the international stakeholders in nanotube measurement science and standardization to build consensus on best measurement practices to assure consistency and quality in the field of carbon nanotubes.
The MSIN10 workshop will be held as a one day satellite meeting to NT10: 11th International Conference on the Science and Applications of Nanotubes. The themes for this year’s workshop are: chemical metrology of nanotubes; physical metrology of nanotubes; metrology of nanotube assemblies and composites; graphene metrology; and nanotube standards development. The workshop will consist of both invited and contributed talks spanning these areas and will close with a round table discussion. A strong effort has been made to ensure global representation among the speakers at MSIN10. The organizers would like to extend an invitation to all NT10 conferees interested in nanotube metrology and standardization issues to join us for a lively discussion at MSIN10.
Posters
There will be no formal poster session associated with the MSIN10 workshop; however, participants are highly encouraged to submit posters related to the metrology, standardization and industrial quality of nanotubes to the main NT10 conference. When submitting abstracts for posters please select “MSIN” from the topic list provided. See http://nt10.org/abstracts_e.html for abstract submission details. We would like to encourage that posters be hung in time for the workshop to allow discussion during breaks, and to leave the posters in place throughout the duration of the main NT10 conference.
Location / Date / Registration Details
The MSIN10 workshop will be held on Sunday June 27, 2010 in the Hilton Bonaventure Montréal (room to be determined) as a satellite meeting of the NT10: 11th International Conference on the Science and Applications of Nanotubes in Montreal, Canada. Attendance is open to all registered NT10 conferees at no additional cost. (See http://nt10.org/registration_e.html). Please note that the deadline for abstract submissions is March 1, 2010.
Program Agenda
08:30 Call to order & Welcome – Alan Steele, National Research
Council Canada
Session: Chemical Metrology (chair: Alan Steele)
08:40 Nicole Grobert (invited), University of Oxford, UK
“Carbon nanomaterials, a showcase for standardised
characterisation”
09:10 Mauricio Terrones (invited), Carlos III University of
Madrid, Spain
“Metrology of Defects in Graphitic Materials: Challenges
and Implications for Developing New Nano-Devices”
09:40 Petra Pötschke (contributed), Leibniz Institute of
Polymer Research Dresden, Germany
"Characterization of the dispersability of different carbon
nanotube materials"
10:00 Break
Session: Standards (chair: Clive Willis )
10:10 Shuji Abe (invited), National Institute of Advanced
Industrial Science and Technology, Japan
"Developing an international standard on terminology for
carbon nano-objects"
10:40 Angela Hight Walker (invited), National Institute of
Standards and Technology, USA
“Documentary Standards Development for Carbon
Nanotube Characterization within ISO/TC 229”
11:10 Charles Clifford (invited), National Physical Laboratory,
UK
"Scanning probe microscopy standardization using and
for measurement of Carbon Nanotubes"
11:40 Jennifer Decker (contributed), National Research
Council Canada
“Measurement vs. Metrology”
12:00 Lunch
Session: Physical
Metrology (chair: Ado Jorio)
13:00 Jacques Lefebvre (invited), National Research Council
Canada
“Single walled carbon nanotube material assessment
using photoluminescence”
13:30 Luiz Gustavo Cancado (invited), Universidade Federal
de Minas Gerais, Brazil
“Mechanism of Near-field Raman Enhancement in
Carbon Nanotubes "
14:00 Martin Kalbac (contributed), Academy of Sciences of
the Czech Republic
“The Role of Doping of Single-Walled Carbon Nanotubes
in Metrology”
14:20 Pascale Launois (contributed), The University of Paris-
Sud 11, France
“X-ray diffraction as a tool for quantitative structural
characterization of "single-walled as well as multi-walled
carbon nanotube batches”
14:40 Aravind Vijayaghavan (contributed), Massachusetts
Institute of Technology, USA
" Voltage-contrast scanning electron microscopy for
statistical analysis of metallic and semiconducting SWNT
devices and location and characterization of defects "
15:00 Break
Session: Graphene (chair:
Ken Bosnick)
15:15 Alain Diebold (invited), University at Albany, USA
" Overview of the metrology of graphene"
15:45 Erlon H Ferreira (invited), The National Institute of
Metrology, Standardization and Industrial Quality, Brazil
“Using Raman spectroscopy as metrological tool in the
study of graphene and other carbon nanostructures”
Session: Applications
16:15 Daniel Resasco (invited) , University of Oklahoma, USA
“Metrology of Single-walled Carbon Nanotube Products
Manufactured in Large Scale”
16:45 Morinobu Endo (invited), Shinshu University, Japan
“Structural Characterization of Multi-walled Carbon
Nanotubes for Commercial Applications and Safety
Issue”
17:15 Wrap-Up
Abstracts:
Nicole Grobert (invited), University of Oxford, UK
“Carbon nanomaterials, a showcase for standardised characterisation”
The rapid development of nanomaterials and more specifically carbon nanomaterials brings an urgent need for a systematic characterisation protocol as well as standardised nomenclature. Following the initial gold rush identifying new carbon nanoforms, the field is slowly maturing. Attempts are now being made to systematically reproduce and isolate specific carbon nanoforms. Carbon nanostructures range from structurally well defined molecules such as fullerenes to larger ‘macromolecules’ for which the atomic arrangement cannot be stoichiometrically precisely defined. Therefore, conventional IUPAC chemical notation is insufficient. Here, we propose a nomenclature based on the morphology which is sufficiently general to conveniently group materials, while remaining specific enough to describe local structural variations.
Furthermore, establishing a rigorous characterisation protocol is rather complex and not very straight forward and hence still not widely distributed or in fact applied. Therefore, we will high-light a few, very simple, procedures that do not rely on the use of state-of-the-art characterisation tools but that can be carried out with equipment available in most laboratories. Taking into account the complexitiy of the problem as such, it is important to establish an inclusive approach to a standardised characterisation protocol, e.g. the more reseach groups are able to follow the protocol the easier it is to get it ingrained in on-going research activities, and therefore paving the way to better classification procedures for nanomaterials.
Mauricio Terrones (invited), Carlos III University of Madrid, Spain
" Metrology of Defects in Graphitic Materials: Challenges and Implications for Developing New Nano-Devices"
Different types of defects within graphene and carbon nanotubes: 1) Structural defects; 2) Bond rotations or grain boundaries; 3) Doping-induced defects; 4) Non-sp2 carbon defects or edge-sites, and 5) Folded (or highly strained) graphene. We will review different techniques used to identify defects: SEM, HRTEM, STM, STS, AFM, Raman spectroscopy (RS), photoluminescence spectroscopy (PLS), thermogravimetric analyses (TGA), electron and thermal transport measurements, etc. The presence of defects and their identification has been overlooked by numerous scientists. However these play a key role in the nanotubes’ physico-chemical properties and even biocompatibility. We will answer the following questions: How do we identify defects efficiently? Could we distinguish among various defects? Would it be possible to establish a protocol able to quantify and control the amount of these defects? How many defects are necessary to fabricate robust polymer composites or 3D architectures? Could I introduce specific defects in order to make materials biocompatible? Could we promote ferromagnetism by introducing specific defects in nanostructures? Could I control their specific reactivity in order to use them as sensors, filters or drug deliverers? etc.
Petra Pötschke (contributed), Leibniz Institute of Polymer Research Dresden, Germany
"Characterization of the dispersability of different carbon nanotube materials"
For the effective use of carbon nanotubes (CNT) excellent distribution and dispersion are essential preconditions. Among the parameters determining the dispersion the dispersability of the CNT materials is of main influence. This quality was assessed studying the sedimentation behavior of CNT under centrifugal forces dispersed in aqueous surfactant solutions at different ultrasonication treatment times using a LumiSizer® apparatus. Different industrial available multiwalled CNT, namely Baytubes® C150P, Nanocyl® NC7000, Arkema Graphistrength® C100, and FutureCarbon CNT-MW showing quite different kinetics were compared. In addition, the particle size distributions were analyzed using dynamic light scattering (DLS, ZetaSizer) and centrifugal separation analysis (CSA).
The best dispersability was found for Nanocyl® NC7000 and FutureCarbon CNT-MW. To prepare stable dispersions of Baytubes® C150P and Graphistrength® C100 five times more energy input was necessary. These finding correlates with the values of deformation stress measurements on the primary agglomerates which resulted in lower values for Nanocyl® NC7000 than for Baytubes® C150P and Graphistrength® C100. In addition, the higher deformation stress of Baytubes® C150P and Graphistrength® C100 is in good agreement with the higher bulk densities of 120-170 and 50-150 kg/m3, respectively. In contrast, Nanocyl® CNT having a low bulk density of 66 kg/m3 exhibits also a lower deformation stress value.
The size of the primary agglomerates in the dry nanotubes powder as evidenced by SEM investigations and laser light diffraction measurements was found not to influence the dispersability. These results help to optimize the processing of nanocomposites depending on the applied carbon nanotube materials.
Shuji Abe (invited),
National Institute of Advanced Industrial Science and Technology, Japan
"Developing an international standard on terminology for carbon nano-objects"
Given the importance of carbon nanomaterials in nanotechnologies, ISO/TC 229 and IEC/TC 113 Joint Working Group 1 (Terminology and Nomenclature) has been developing a technical specification (TS) on vocabulary for carbon nano-objects, which will be published as Part 3 of the TS 80004 series [1]. The most important aspect of this work is harmonization with a rational hierarchical system of terminology under development for nanotechnologies. This means, for example, the definition of 'carbon nanotube' must follow the definition of the parent term 'nanotube'. However, in some cases the hierarchical approach needs to be compromised due to the specific usage of individual terms or due to the limited scientific knowledge of material characteristics. The evolution and future directions on terminology and nomenclature for carbon nanomaterials will be discussed.
[1] ISO TS 80004-3: 2010, Nanotechnologies -- Vocabulary -- Part 3: Carbon nano-objects.
Angela Hight Walker (invited), National Institute of Standards and Technology, USA
“Documentary Standards Development for Carbon Nanotube Characterization within ISO/TC 229”
Carbon nanotubes (CNTs) play a prominent role within the International Standards Organization (ISO), Technical Committee (TC) 229 Nanotechnology. ISO/TC229, established in 2005, has 32 member body countries participating and 10 countries observing, and works in cooperation with multiple organizations such as CEN, OECD, VAMAS, Asia Nano Forum, BIPM, IUPAC among others. CNTs are the focus of the vast majority of work items within Working Group 2 (WG2), Measurement and Characterization, one of the four WGs within the TC. WG2 is a joint committee with the International Electrotechnical Commission (IEC)/TC 113. The work program for single-wall carbon nanotubes is based on a matrix of six parameters verses multiple measurement methods. Many of these technique-based projects have moved into the final stages of development. Also, multiwall carbon nanotube characterization is under consideration within WG2. A summary of the documentary standards under development pertaining to carbon nanotubes will be presented, particularly those within ISO/TC229, but also those relevant activities in other standards developing organizations.
Charles Clifford (invited), National Physical Laboratory, UK
" Scanning probe microscopy standardization using and for measurement of Carbon Nanotubes "
Scanning probe microscopy (SPM) family are powerful instruments that can give dimensional, mechanical, electrical and some chemical information at the nanoscale and are thus ideally suited to studying carbon nanotubes. In 2004, international standardisation of SPM methods began with the creation of a sub-committee on scanning probe microscopy in ISO/TC 201 on surface chemical analysis. In this talk, we highlight the work that is being undertaken in this technical committee with several examples that are being led by NPL. The first is a draft ISO standard on methods to calibrate AFM normal spring constants, necessary to give quantified force. The second is terminology, which include 76 SPM acronyms, 33 definitions of SPM techniques, 6 terms for contact mechanics and 147 SPM terms. The talk will also highlight research being undertaken at NPL analyzing carbon nanotubes using various SPM techniques. These include using carbon nanotubes and other samples to determine the AFM tip shape. This is critical for high resolution, accurate dimensional measurements. Tip enhanced Raman spectroscopy (TERS) is also being used to characterize carbon nanotubes to give some chemical information at the nanoscale. Methods to assess dispersions of carbon nanotubes are also being investigated.
Jennifer Decker (contributed), National Research Council Canada
“Measurement vs. Metrology”
Metrology forms the bridge from science to technology. Precise knowledge of characteristics such as traceability, measurement uncertainty, reproducibility, repeatability is what differentiates one single measurement observation from a metrological measurement. Metrology differs somewhat from measurement in the manner of scope. Traceability to a single reference means that all measurements can be compared with each other on a common scale. The SI system of units provides this global framework. Science continues to push on frontiers of knowledge, and the transformation of science into technology is underpinned by profound understanding and predictive models, which can only be attained via measurement results which are widely reliable and comparable. Reference materials provide a means to establish a base-line result with which to compare other materials measured the same way. Protocols for sample preparation [1] and measurement methods are important contributors to comparability. The content of such protocols is based on measurement repeatability within labs and duplication of results amongst peer labs. At this formative stage of our knowledge, independent demonstration of the same result validates measurement and uncertainty models and provides confidence in the robustness of a method. Statistical methods specifically targeted for comparing measurements have been developed [2]. This talk outlines these cornerstone concepts with some specific examples.
1. Decker, J.E., et al, 2009 “Sample Preparation Protocols for Realization of Reproducible Characterization of Single-Wall Carbon Nanotubes”, Metrologia 46 (6), 682-692.
2. Decker, J.E., Steele, A.G., Douglas, R.J. 2008 "Measurement science and the linking of CIPM and regional key comparisons", Metrologia 45(2), 223-232.
Jacques Lefebvre (invited), National Research Council Canada
“Single walled carbon nanotube material assessment using photoluminescence”
After the first report of fluorescence (or alternatively photoluminescence) in individualized micelle encapsulated single walled carbon nanotubes, the nanotube community has quickly recognized its potential as a powerful tool for materials assessment. I will describe with several examples taken from the literature how the method is currently being used, and highlight the important advances that greatly benefited from photoluminescence. As with every method, users ought to be aware of some fundamental issues setting the limitations of their characterization tool and this is more so true for photoluminescence. Nanotube luminescence is primarily a very active research topic and the findings might affect the conclusions of a sample analysis. I plan to give an overview of the current knowledge and how it impacts materials assessment. Finally, I will outline some important guidelines to users of photoluminescence as a characterization tool which are soon to be published as an ISO Technical Specification.
Luiz Gustavo Cancado (invited), Universidade Federal de Minas Gerais, Brazil
“Mechanism of Near-field Raman Enhancement in Carbon Nanotubes"
Many experimental works have recently shown that near-field Raman is an useful optical technique for the study of carbon nanotubes on the nanometric scale. The high-resolution achieved in these experiments (~10-30 nm) made it possible to resolve local variations in the Raman spectrum along an isolated single-wall carbon nanotube, which would otherwise be hidden in far field measurements. In spite of the great potential of near-field Raman on the development of the science of carbon nanotubes, a careful analysis taking in account its theoretical basis still missing. In this talk, we present a theory describing the near-field Raman enhancement of carbon nanotubes. The theory predicts that the near-field Raman intensity is inversely proportional to the 10th of the tip-sample distance. Supporting the theory, experimental results of near-field Raman measurements performed on distinct serpentines carbon nanotubes (with different chiralities) is presented. The experimental data show that distinct peaks present in the near-field Raman spectra originated from an specific tube present the same enhancement for a given tip-sample distance. These results indicate that the near-field enhancement does not dependent considerably on the symmetry of the Raman mode, but mainly on the field enhancement factor intrinsic from the near-field probe used in the experiment.
Martin Kalbac (contributed), Academy of Sciences of the Czech Republic
“The Role of Doping of Single-Walled Carbon Nanotubes in Metrology”
In the present work we discuss the influence of doping single-walled carbon nanotubes on their use in metrology, based on Raman spectroscopy. In this connection we have analyzed the radial breathing mode intensity vs. electrode potential profiles in the Raman spectra at many different laser excitation energies. It is shown that the charging of carbon nanotubes causes a broadening of the resonant Raman profiles and also give rise to a shift in energy of the resonance maximum. The change of the resonance profile has important practical consequences on the quantitative determination of the amount of a given (n,m) tube that is contained within a given nanotube sample. This is because the presence of carriers will have a different effect on the radial breathing mode intensity at different laser excitation energies. The effect of doping is in particular important in the case of metallic tubes. In contrast to semiconducting tubes, in the case of metallic tubes for which the laser is close to their maximum in the resonance profile, the Raman intensity is strongly bleached by natural doping, and thus the amount of these particular nanotubes present in a given sample when evaluated on the basis of a measurement of the radial breathing mode intensity might be strongly underestimated. Particular attention is given to analysis of their metrological effect.
Pascale Launois (contributed), The University of Paris-Sud 11, France
“X-ray diffraction as a tool for quantitative structural characterization of "single-walled as well as multi-walled carbon nanotube batches”
Low-cost methods to characterize carbon nanotubes (CNT) are strongly needed in the context of their large-scale industrial production. Methods such as electron microscopy or Raman spectroscopy cannot be used easily in a quantitative way on macroscopic nanotube samples, due to the local character of the method in the first case and to resonance effects in the second case.
X-ray diffraction (XRD) allows one to probe several milligrams of nanotube samples. Low-cost experiments can be performed on laboratory anodes, the use of synchrotron radiation being not necessary here. We will show that analysis of XRD data using adequate modeling of diffraction patterns gives access to key structural parameters of nanotube batches such as : (i) mean-diameter, distribution in diameters, organization in bundles if any, for single-walled (SW) CNT [1], (ii) number of walls, inter-wall distances and possible organization in bundles for multi-walled (MW) CNT [2]. Nano-contaminants (catalyst nanoparticles, graphitic shells, etc) are also probed by XRD. For macroscopic quantities of single helicity nanotubes, XRD would allow determination of the helicity. Moreover, preferential orientation of nanotubes, in composites for instance, are quantified using XRD [3].
We will present XRD diffraction patterns of SW, double-walled and MWCNT from several academic and industrial suppliers and we will discuss their structural characteristics.
[1] G. Charron et al., New J. Chem. 33, 1211 (2009)
[2] J. Cambedouzou et al., Phys. Rev. B 79, 195423 (2009)
[3] V. Pichot et al., Phys. Rev. B 74, 245416 (2006)
Aravind Vijayaghavan (contributed), Massachusetts Institute of Technology, USA
"Voltage-contrast scanning electron microscopy for statistical analysis of metallic and semiconducting SWNT devices and location and characterization of defects"
Single-wall carbon nanotubes (SWNTs) are edging closer to electronic applications, with successful techniques now available for sorting and large-scale integration. When SWNTs are integrated into arrays or circuits at high densities, it is required to characterize the number and location of metallic and semiconducting devices among them. This is true even when such arrays are assembled using high-purity semiconducting SWNT solutions since it becomes critical to locate stray metallic devices that would significantly affect overall performance.
Here, we describe voltage-contrast scanning electron microscopy (VC-SEM), as a fast, user-friendly and non-invasive technique for the simultaneous electronic characterization of arrays of SWNTs devices. We demonstrate how metallic and semiconducting SWNTs can be distinguished in an SEM under the influence of a substrate bias, and describe the underlying mechanism. In addition, devices containing SWNTs with defects can also be identified. On closer inspection, we can reveal the location and nature of such defects with nano-scale resolution (Featured on cover of Carbon 48(4)). Anomalies such as charge-injection into the substrate which leads to hysteresis, as well as in-situ characterization of the creation and annealing of defects (defect engineering) will also be demonstrated using VC-SEM.
Vijayaraghavan, A., et al., Imaging defects and junctions in single-walled carbon nanotubes by voltage-contrast scanning electron microscopy, Carbon 2010, 48(2), 494
Vijayaraghavan, A.; et al., Imaging electronic structure of carbon nanotubes by voltage-contrast scanning electron microscopy. Nano Research 2008, 1, 321
Vijayaraghavan, A.; et al., Ultra-Large Scale Directed Assembly of Single-Walled Carbon Nanotube Devices. Nano Letters 2007, 7, 1556-1560.
Alain Diebold (invited), University at Albany, USA
"Overview of the metrology of Graphene"
Graphene is considered a strong candidate for extending transistor technology and as a material for beyond CMOS switches. New materials such as graphene are difficult to find, manipulate, and measure. Chemical Vapor Deposition and annealing of SiC wafers both may provide the large area graphene necessary for device manufacturing. There are many questions about how to compare the many physical and electrical measurements and evaluate new growth methods. This talk will discuss many of the key measurement areas. The electrical properties of graphene depend on the number of layers, the stacking of multi-layers, and rotational orientation. Multiple characterization methods are sensitive to the number of layers including transmission electron microscopy, Low Energy Electron Microscopy, nano-Raman, optical absorption, and scanned probe methods. Another question is the impact of corrugation on electrical properties. Recent AFM measurements prove the impact of the substrate roughness on corrugation. The ultimate reason for the interest in graphene is the high mobility observed by many researchers. The literature shows that mobility depends on the source of the graphene and stacking configuration. A comparison of some of the data will be shown. In addition, the electrical measurements point to interesting nano-scale electrical properties. Quantum confinement and Berry Phase corrections are two examples of quantum phenomena that alter the properties of nano-scale structures. This talk will provide a high level review of the status of graphene metrology.
Erlon H Ferreira (invited), The National Institute of Metrology, Standardization and Industrial Quality, Brazil
“Using Raman spectroscopy as metrological tool in the study of graphene and other carbon nanostructures”
Graphene is a promising material in the development of future nanodevices. Developing methods of characterization and creating metrological standards is an issue of great relevance in this process. Here we present different approaches in the study of defects and deformations in graphene done at the Division of Materials in Inmetro. Raman is the most common technique used to study carbon materials and it is also the most suitable to study the presence of defects in graphene. We have done a thorough analysis of the Raman spectrum of a monolayer graphene as we increase the disorder in the system by a systematic and controlled ion bombardment. In special, the evolution of the intensity ratio between the G band (1585 1/cm) and the disorder-induced D band (1345 1/cm) with ion dose is accurately determined, providing a spectroscopy-based method to quantify the number of defects in that system. This evolution can be fitted by a phenomenological model which is in conceptual agreement with a well-established amorphization trajectory for graphitic materials, but differs substantially from the broadly used Tuinstra-Koening relation for the small disorder. Defects have also been created on HOPG using a focused ion beam (FIB) which delivers high energy ions (30 keV) in a controlled way. Raman spectroscopy is then used for testing FIB performance and shows to be a promising metrological tool to test and compare progresses in ion beam optics for soft modification. Some other applications of Raman spectroscopy in the study of carbon nanostructures will also be addressed.
Daniel Resasco (invited), University of Oklahoma, USA
"Metrology of Single-walled Carbon Nanotube Products Manufactured in Large Scale"
Since June 2008, SWeNT is operating at its 18,000-square-foot manufacturing facility. The new plant has capacity for producing several Kg/day of SWNT products, obtained with the CoMoCAT process. The commercial products offered by SWeNT include: SG65 (highly enriched in (6,5) SWCNT type), SG76 (enriched in (7,6) and (8,7) SWNT types), CG200 (broader distribution of chiralities with average diameter of 1.0 nm). CS100 (conductive silica, a nano-hybrid SWNT/SiO2 nanoparticles). Thin SWNT films and nanotube inks, and SMW (special multi-walled carbon nanotubes of narrow diameter). The narrow distribution of diameters and chiralities in the SG65 CoMoCAT sample prepared at 750°C in CO on the Co-Mo/SiO2 catalyst has been previously reported and widely corroborated in several laboratories. By varying the operating parameters and catalyst formulation one can vary the distribution of (n,m) nanotubes in a reproducible manner.
Quality control specifications have been developed based on established metrology for large-scale batches. It must be taken into account that production and quality-control operators are not researchers; therefore, each specific technique must be designed so it is uncomplicated for the operator to conduct on a routine basis and obtain reproducible results. The following quality parameters have been established, and the specifications are applied to every sample produced:
1) Raman Parameters (λ=D/G, and absolute G intensity).
2) TGA parameters (T1 and R%)
3) Optical Absorption (parameters P2B and S2B)
4) Photoluminescence
5) Suspendability/precipitation factor (P).
In this contribution, we describe a method recently implemented to assess the purity of single-walled carbon nanotube (SWCNT) bulk samples based on Raman spectroscopy of liquid suspensions. The new method has higher reproducibility and quantitative precision than those previously used. It consists of measuring the G-band intensity of liquid suspensions of SWCNT samples as a function of solid concentration. A simple equation is proposed in which one of the two adjustable parameters is the SWCNT purity. The method has been applied to a series of samples of similar characteristics, but varying quality. The results are compared to those obtained on the same series of samples using standard analytical techniques, including electron microscopy, thermogravimetric analysis and optical absorption.
Morinobu Endo (invited), Shinshu University, Japan
"Structural Characterization of Multi-walled Carbon Nanotubes for
Commercial Applications and Safety Issue"
Multi-walled carbon nanotubes (MWNTs) have pursued their end uses in numerous areas (e.g., nanocomposite, energy storage, sensors, field-emission displays, radiation sources, devices, actuator and probes) by exploiting their novel physical and chemical properties derived from their atomistic configurations as well as various geometrical structures. Industrially produced carbon nanotubes reach 1000 ton/year, because the cost-effective catalytic CVD technique for producing carbon nanotubes in a large scale has been established. Therefore, a synergistic effect of an industrially produced carbon nanotubes and the newly created end-uses will cut down their price by at least 10 percent of the current value in the near future. However, there is no standard way to assess the quality of MWNTs, even though their quality is extremely important to make a product with a desired performance. Here I will describe the current status of MWNTs productions, and then their current usages, by suggesting the several important measurement methods to evaluate basic properties of MWNTs and quality of commercial products for standardization as well as safety issue of MWCNTs.
