Carbon NANOTUBES de carbones La prochaine vague technologique

Table des matières Properties of CNTs Applications futures possibles How do we produce them? Questions??? Références What are Carbon Nanotubes? Problèmes

Quest-ce quun nanotube de carbone?

What is it? Iijima discovered them in 1991 Feuille de graphite roullée en un cylindre Liens sp2 SWNT vs MWNT Forces de Van der Vaals tiennent les épaisseurs ensemble. End(s) in the shape of buckyballs

Comment les reconnaître? Les CNTs sont identifiés par un couple dentier (n,m)

Quelques propriétés

Caractéristiques des CNTs SWNT diameter: 0.4 to 3 nm – times smaller than a hair MWNT diameter: ~1.4 to 100 nm Length: up to several millimeters at best, usually a few microns

Properties of CNTs Youngs modulus of ~1TPa for SWNT and up to 1,28TPa for MWNT –Steel is at ~0.2TPa… –Wow! Highest tensile strength ever mesured –Bone – 130 –Steel - ~800 –Kevlar – 3620 –CNT – Mechanical properties -une paille qui se déplie

Properties of CNTs 3 cas : - armchair SWNTare metals -(n-m) divisible by 3 ar semiconductors with tiny gap -others are semiconductors with ban gap depends on (diameter) -1 Semblable pour les MWNTs The nanotubes conduct current ballistically (without scattering) - phonons propagate easily along a CNT -high current with virtually no heating Superconductivity observed at low pressure (0.55K) Expérimentalement, SWNT peut supporter jusquà 10 9 A/cm 2 pour un métal normal, cest seulement ~ 10 5 A/cm 2 (vaporisation!) Electrical properties

Des applications intéressantes

Applications of CNTs Conductive and high-strength composites; Field emission displays and radiation sources; Lampes basée sur les nanotubes;(>8000 hours) One-dimensional electronics Energy storage and energy conversion devices; 1.Propriétés électrochimiques des CNTs permet la création de supercondensateurs 2.Electromechanical actuators might be used in robots…eventually (1)

Applications of CNTs Nanometer-sized semiconductor devices Vestes anti-balles Média dentreposage dhydrogène; Anti-earthquake buildings Production de rayons X et micro-ondes Supercapacitors Cancer treatment ( seen in a previous presentation ) (2)

La production de nanotubes de carbone

CNT production 1.Laser abblation 2.Chemical vapor deposition 3.Arc discharge 4.Plasma torch

CNT production Carbon arc discharge 2 carbon electrodes (3 and 4) vaporized with catalityc metal Applied voltage causes plasma between electrodes Arc-electrode interaction phenomena limitations

CNT production Plasma torch: MegaWatt power scale in industry Chercheur de McGill (J-L Meunier): –Possibility to size-up the system Plasma torch

Problèmes

Problems with CNTs Cost of production - high purity: 750$/g - with impurities: 60$/g Diversité des nanotubes –No method available to effectively separate them and/or produce CNT with only one twist Limitations expérimentales dans la production –Par exemple la vitesse dévaporation du tungstene sur les électrodes (1)

Problems with CNTs Méthode dassemblage complexes pour des «réseaux» de nanotubes Moins de problèmes avec les MWNTs Multiton production in early 1990s Hyperion Catalysis International Inc In Japan, plans for 120 ton/year of MWNT at 75$/kg (2)

Références 1.Physical properties of carbon nanotubes, ADAMS II, T., (2000) ( 2.Carbon nanotubes and related structures:New materials for the 21st century, HARRIS, P.J.F., Am. J. Phys, Vol 72, no.3, p.415, March Atomic chiken wire, LOUIE, S.,( 4.Carbon nanotube, Wikipedia, ( 5.Carbon nanotubes roll on, Physics Web, (june 2000) ( 05]

Références(2) 6.Multiwall carbon nanotubes, Physics Web, (june 2000) ( 7.Carbon nanotubes from the dissociation of C 2 Cl 4 using a dc thermal plasma torch, HARBEC D.,MEUNIER J-L., GUO L., J. Phys. D: Appl. Phys. 37, pp , ,(2004) 8.Fullerene synthesis in the graphite electreode arc process:local plasma characteristics and correlation with yield, Saïdane K, et al., J. Phys. D: Appl. Phys. 37, pp ,(2004) 9.Carbon Nanotubes--the Route Toward Applications, Science, Vol 297,no.5582, pp

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