NanotechnologyNanoscience

Modeling and Simulation

Develop models of nanomaterials processing and predict bulk properties of materials that contain nanomaterials

Bridge models between scales, from atoms to self-assembly to devices

Manufacturing & Processing

Develop unit operations and robust scale-up and scale-down methodologies for manufacturing

Synthesis Separation Purification Stabilization Assembly

Characterization tools

Develop real-time tools for measuring and characterizing nanomaterials, particularly online and in-process

Synthesis and Assembly

Develop new paradigms to create nanoscale building blocks

Develop approaches for controlled assembly of nanocomposites and nanostructures

Priority R&D Needs for Nanotechnology Commercialization

Characterization tools

Develop analytical tools for measuring and characterizing nanomaterials

Chemical Industry Application AreasCatalysts, coatings, ceramics, sorbents, membranes

Joint nano-Metrology Needs

1. Large volume nanotube characterization of electronic properties

• Bandgap distribution • Could be useful for characterizing other

nanoparticles• On wafers or as grown

2. In line particle characterization (1-50nm)• Particle size distribution• Particle surface morphology distribution

Large Volume Electronic Property Characterization

• Currently no single tool that can characterize bandgap distributions of large numbers of nanotubes.

• Fluorescence appears to be the most likely characterization tool, but research is needed:– Fluorescence cross sections of CNTs vs diameter &

chirality & bandgap in different chemical environments – Need to characterize interactions that can cause

quenching (Bundles, SiO2, High K, chemicals)– Identify conditions where fluorescence could be

applicable

• Novel concepts for canceling quenching??

In situ Nano-particle (sub 50nm) Monitor

• Current techniques are not currently compatible with in situ monitor applications– Small angle X-ray scattering

• Measure particle size distribution and surface area• Compatibility with flow cell demonstrated

– Brownian motion techniques• Sensitive to flow, so not compatible with in situ application

– TEM Holography• Particle size & surface morphology in development or

excursions, limited statistics• Not compatible with in situ

– Particle mass spec: Proposal• Particle weight, composition & surface chemistry• Valuable in development & excursions, not in situ

– MEMs Particle detectors: TBD

Real-Time Characterization

• In addition to ongoing efforts in development of advanced characterization tools for R&D, there is a need to develop deployable process-monitoring tools that can be used to ensure nanomaterial and nanoproduct consistency on a manufacturing scale. Such instruments would include real-time, on-line characterization tools and rapid quality control (QC) tests for samples. Needs include monitoring the following:

• in situ particle size and shape • in situ composition or function (including charge; surface

energy; functionalization; magnetic, electrical, or optical properties, etc.)

• surface chemistry at nanoscale, including fractional coverage and thickness of coatings on nanoparticles

• quality of particle dispersion in a solid phase

• Large-Volume Electronic Property: Work in large-volume electronic property characterization is needed because there is currently no single tool that can characterize bandgap distributions of large numbers of carbon nanotubes. Fluorescence appears to be the most useful potential characterization tool as it may yield information on cross-sections of carbon nanotubes (CNT) vs. diameter, chirality and bandgap in different chemical environments. However, more research is needed to identify applicable conditions. Quenching of fluorescence from conditions such as the presence of bundles, SiO2 or other chemicals and high dielectric constant (K) could limit the applicability of this technique and will require new concepts to cancel the quenching.

• In Situ Monitoring: Current analytical techniques for nano-particles cannot yet be used for in situ monitoring. Small angle X-ray scattering can measure particle size distribution and surface areas, and has demonstrated compatibility with flow cells. Micro-electro-mechanical systems (MEMS) based particle detectors may prove useful. A proposed particle mass spectrometer to characterize particle weight, composition and surface could be valuable in development and excursions, but not for in situ applications. Brownian motion techniques are sensitive to flow, and so will not be useful for in situ applications. TEM holography has been used to study particle size and surface morphology in development or excursion, but is also not compatible with in situ monitoring.

Utility of various research tools in nanomaterial property characterization

Nanomaterial Properties

Research Tool Application

Small Angle X-ray scattering

Mass SpectroscopyMicroscopy (SEM/TEM)

Particle size YesYes (1000 particles/sec)

Yes (5000/hour SEM, TEM ?)

Particle size distribution Yes Yes Yes

Bulk composition NoYes (photo ionization of sample)

No

Surface composition No ? Yes

Surface composition-ligands No ? ?

Particle structure(Architecture)

? ?Aberration Corrected TEM carbon sensitivity?

Level of dispersion/aggregation Yes ? Yes (if in matrix)

Particle shape ?Yes, with ion mobility measurement

Yes

Particle aspect ratio ? No Yes

Surface charge No? ? ?

Surface functionality No? ? Yes?

Homogeneity/Heterogeneity (surface, size, composition)

? NoYes (dependent on statistics)

Heterogeneity of population ? ? Depends on statistics

Heterogeneity of single particle ? ? Yes

? indicates utility still to be determined based on input from other experts

Magneto-electronic and transport properties

The experimental capabilities essential for further understanding these properties of nanostructures include:

• Statistical measurement of the electronic transport properties of nanostructures

• Correlation of electronic transport properties with atomistic structure in the nanostructure

• Measurement of the properties of contacts to nanostructures, and correlation with atomic structure of nanostructure/metal interface

• Measurement of the optical properties of nanostructures and of opto-electronic processes

• Measurement of the temperature dependence of nanotube bandgaps, addressing the role of phonons

• Effect of adsorbates on nanowire conductivity• Large-volume electronic properties

Nano-mechanical and interface properties:

• Measurement of the three-dimensional

mechanical response of nanostructures to controlled applied strain

• Measurement of the mechanical response of nanostructures to electronic, magnetic, optical, and thermal stimulation

• Atomic imaging of defects, failure modes, dislocations, grain boundaries, interfaces, and similar properties

• Effect of substrate interactions on nanostructure deformations

Thermal properties

• Characterization of phonon dispersion in nanomaterials and interfaces

• Measurement of thermal transport in nanostructures, including role of interfaces

• Temperature dependence of thermal properties