Carbon nanotubes: from the structure to electronic properties Andrzej Burian A. Chelkowski Instituite of Physics, University of Silesia, Katowice, Poland
What are carbon nanotubes (CNTs)? Electronic structure of CNTs Transport properties of CNTs – connecting CNTs How much we can learn about the structure of CNTs from diffraction experiments? Neutron and X-ray diffraction – analysis of data in real and reciprocal space Conclusions
The unrolled honeycomb lattice of a nanotube n, m are integers
S. Iijima, Nature 354 (1991) 56 J.W.G. Wildoer et al. Nature 391 (1998) 59 HRTEM STM Electron diffraction Ph. Lambin et al. Carbon 40 (2002) 1653
Electronic structure of CNTs (12, 0)(13, 0)(12, 6) N. Hamada, S. Sawada, A. Oshiyama, Phys. Rev. Lett. 68 (1992) 1579
n-m divisible by 3 metallic nanotubes n-m not divisible by 3 semiconducting nanotubes yellow dots – metallic nanotubes blue dots – semiconducting nanotubes
R. Saito, G. Dresselhaus, M.S. Dresselhaus, J. Appl. Phys. 73 (1993) 494
J.W.G. Wildoer et al. Nature 391 (1998) 59
Connecting carbon nanotubes with pentagon – heptagon pair defects (12, 0) – (9, 0) (12, 0) – (8, 0) (12, 0) – (9, 0) R. Saito, G. Dresselhaus, M.S. Dresselhaus, Phys. Rev. B 53 (1996) 2044 t is nearest-neighbour transfer integral approx eV Stone-Wales defect
The atomic structure of the (8, 0) – (7, 1) semicinductor-metal junction L. Chico et al. Phys. Rev. Lett. 76 (1996) 971. Connecting carbon nanotubes with pentagon – heptagon pair defects
Z. Yao et al. Nature 402 (1999) 273
FET room temperature single- electron transistor Richard Smalley and Cees Deckker groups
nanotube-based memory system bit size 2 nm 2 SWCNT charged buckyball (K + ) Y-K. Kwon, D. Tomanek, M. Brenhob, R. Enbody, IEEE99 „bit 0” „bit 1”
diffraction experiment 2θ scattering angle scattering vector monochromatic beam is the wavelength
What is a pair correlation function?
Y. Waseda
Motivation Industrial scale applications of the CNTs needs: low cost and efficient fabrication high purity (no contamination by graphite or graphite-like carbon and catalysts preparation of carbon nanotubes with uniform chirality and diameter production of aligned nanotubes
Oxford MWCNTs neutron diffraction data Institute Laue-Langevin A. Burian et al. Phys. Rev. B 59 (1999) 1665 carbon nanotubes only (0 0 2l) and (h k 0) reflections
ESRF ID15 – high-energy beam line Namur nanotubes cathalitic arc- discharge method
Template synthesis of carbon nanotubes T. Kyotani, L. Tsai, A. Tomita, Chem. Mater. 8 (1996) 2109
Stepped carbon nanotubes synthetized in anodic alumina template J. Lee at al. Chem. Mater. 13 (2001) 2387
The incident beam perpendicular to the nanotube axis The incident beam parallel to the nanotube axis
inter-layer spacing 3.51 Å (3.35 Å for graphite) r1r1 r1r1 r2r2 r3r3 r2r2
GEM diffractometer at RAL (pulsed neutrons)
A. Burian et al. Diam. Relt. Mater. 13 (2004) 1261 real space
reciprocal space computer generated Cartesian coordinates of atoms for the graphite structure (a single layer) {x,y,z} Cartesian coordinates of atoms for nanotubes {X,Y,Z} structure factor
J. Koloczek et al. Diam. Relt. Mater. 13 (2004) 1218
CONCLUSIONS: X-ray and neutron diffraction are efficient tools which allow to obtain precise structural information about carbon nanotubes on an atomic level. The nature of the atomic arrangement within a single layer, layer stacking, a degree of distortion of the hexagonal network and the presence of defects can be deduced from such data. Information about alignment of carbon nanotubes can be obtained from analysis of 2D diffraction data for as prepared samples. Knowledge of the structure of carbon nanotubes will be useful for controlling quality of carbon nanotubes in global sense.
COOPERATION: J.C. Dore, University of Kent, Canterbury, UK J.B. Nagy, Namur group, Belgium A.Fonseca, Namur group, Belgium T. Kyptani, Tohoku University, Japan J. Sloan, Oxford University, UK H.E. Fischer, ILL, France A.C. Hannon, RAL, UK V. Honkimaki, ESRF, France J. Koloczek, University of Silesia, Poland L. Hawelek, University of Silesia, Poland