Carbon Nanotubes Chirality - Nanotechnology - Lecture Slides, Slides of Nanotechnology

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PROCESS TO CONTROL CARBON

NANOTUBES CHIRALITY

Edson P. Bellido Sosa

INTRODUCTION

• CNTs are allotropes of carbon
• Composed of sp^2 bonds
• Highest length-to-diameter ratio
• MWCNTs and SWCNTs
• Extraordinary mechanical properties Young modulus 1-5TPa Tensile strength 11-150GPa
• Efficient thermal conductors  thermal conductivity 3500 W/(m·K)

S. Iijima, "HELICAL MICROTUBULES OF GRAPHITICCARBON," Nature, vol. 354, pp. 56-58, Nov 1991.

S. Iijima and T. Ichihashi, "SINGLE-SHELL CARBON NANOTUBES OF 1-NM DIAMETER(VOL 363, PG 603, 1993)," Nature, vol. 364, pp. 737-737, Aug 1993.

CNT STRUCTURE

• Describe in terms of graphene lattice vectors
• CNT=rolled graphene
• Unit cell spanned by a 1 and a 2 and form and angle of 60°| a 1 |=| a 2 |=2.461Å
• Circumference of the tube c = n a 1 + m a 2 ; c also called Chiral vector
• CNTs usually describe by (n,m)

http://www.personal.reading.ac.uk/~scsharip/Wedge.jpg

CNT STRUCTURE

• n = m (chiral angle = 0°) tubes are called "armchair"
  • m = 0 (chiral angle = 30°) "zigzag"

http://en.wikipedia.org/wiki/Optical_properties_of_carbon_nanotubes

METHODS TO OBTAIN MONODISPERSE

SWCNTS

• Selective chemistry
• Selective destruction
• Dielectrophoretic separation
• Ultracentrifugation
• Selective growth

M. C. Hersam, "Progress towards monodisperse single-walled carbon nanotubes," Nature Nanotechnology, vol. 3, pp. 387-394, Jul 2008.

CLONING CARBON

• Baked in air and washed with washed in hydrochloric acid.
• Fluorination process
• Hydrazine treatment, and final treatment with H 2 SO 4 -H 2 O 2
• Polymer wrapping PEI-Fe(NO 3 ) 3 solution was mixed with 5 mL of aqueous wrapped SWNTs

R. E. Smalley Chemical Society, vol. 128, pp. 15824-15829, Dec 2006., et al., "Single wall carbon nanotube amplification: En route to a type-specific growth mechanism," Journal of the American

CLONING CARBON

R. E. Smalley Chemical Society, vol. 128, pp. 15824-15829, Dec 2006., et al., "Single wall carbon nanotube amplification: En route to a type-specific growth mechanism," Journal of the American

TUNING NANOPARTICLES

• Nano-catalyst fabricated in a microplasma reactor
• Plasma of nickelocene (pure Ni particles)
• Plasma of nickelocene and ferrocene (NixFe1-x)
• CVD process to fabricate SWCNTs

2.0 ppm 2.6 ppm (^) 1.3 ppm 2.2 ppm

W. H. Chiang and R. M. Sankaran, "Linking catalyst composition to chirality distributions of as-grown single-walled carbon nanotubes by tuning NixFe1-xnanoparticles," Nature Materials, vol. 8, pp. 882-886, Nov 2009.

TUNING NANOPARTICLES

W. H. Chiang and R. M. Sankaran, "Linking catalyst composition to chirality distributions of as-grown single-walled carbon nanotubes by tuning NixFe1-xnanoparticles," Nature Materials, vol. 8, pp. 882-886, Nov 2009.

THANK YOU

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Rebuttal : Nanowire photonics

Edson P. Bellido Sosa

Comment: The introduction part didn’t include basic concepts from

spectroscopy, necessary to be able to interpret the results from the

presented research work.

Yes, I did not considered necessary to mentioned those basic concepts of

characterization techniques since I thought the audience had this

knowledge. However, during the presentation I have noticed that this was

not the case.

Comment: It should have been illustrated the design requirements and

working principle of at least one potential application such as the procedure

to make a logic in a photonic computer or the remote detection of threat

agents.

I chose to only talk about one application in detail since the time of the

presentation was limited.

Photonic nanowires – Lecture review

The introduction part didn’t include basic concepts from spectroscopy,

necessary to be able to interpret the results from the presented research work.

It was shown in detail only the procedure to synthesize the nanowires.

It should have been illustrated the design requirements and working principle

of at least one potential application such as the procedure to make a logic in

a photonic computer or the remote detection of threat agents.

Elemental devices like‘optical microcavity’ or ‘ring resonators’ which enable

many photonic applications were not mentioned.

Limitations on the controlled connection or assembly of nanowires, which is

fundamental to enable potential applications, were not illustrated.

Alfredo D. Bobadilla

By: Mary Coan

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