1 / 22

Irradiation-Induced Effects in Carbon Nanotubes and Graphite

Irradiation-Induced Effects in Carbon Nanotubes and Graphite. A. Krasheninnikov , J. Pomoell, J. Kotakoski, K. Nordlund, and J. Keinonen Accelerator Laboratory, University of Helsinki , Finland E. Salonen, Laboratory of Physics, Helsinki University of Technology , Finland

brandycaldwell
Télécharger la présentation

Irradiation-Induced Effects in Carbon Nanotubes and Graphite

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Irradiation-Induced Effects in Carbon Nanotubes and Graphite A. Krasheninnikov, J. Pomoell, J. Kotakoski, K. Nordlund, and J. Keinonen Accelerator Laboratory, University of Helsinki , Finland E. Salonen, Laboratory of Physics, Helsinki University of Technology , Finland P. Lehtinen, A. Foster, Y. Ma, and R. M. Nieminen Laboratory of Physics, Helsinki University of Technology, Finland M. Sammalkorpi, A. Kuronen, and K. Kaski , Laboratory of Comp. Eng., Helsinki University of Technology, Finland F. Banhart, University of Mainz, Germany S. Stuart, Clemson University, USA

  2. Outline of the talk 1. Irradiation of carbon nanotubes. Why interesting? 2. Channeling of heavy ions through the cores of multi-walled carbon nanotubes. 3. Irradiation-induced magnetism in C-systems. 4. Conclusions and outlook.

  3. Carbon nanotubes Sumio Iijima, 1991

  4. Physical properties and potential applications • Nanoelectronics (electronic properties) • quantum wires, memory elements, nanotube-based quantum dots • Lighting elements (electron field emission) • Current carrying capacity 1000 MA/cm2 (Copper ~ 1 MA/cm2) • Supersensitive gas sensors (electronic properties ) • Superstrong materials (mechanical properties) • Y ~ 1 TPa (Highest among known materials, about five times the value for steel ) • Other applications …

  5. Irradiation of nanotubes: why interesting? • Coalescence and welding of nanotubes under electron irradiation; M.Terrones et al., Phys.Rev.Lett. 89 (2002) 075505 • e-beam engineering; J. Li and F. Banhart, Nanolett 4 (2004) 1143

  6. Irradiation of nanotubes: why interesting? • Electronic transport in quasi-one-dimensional systems;irradiation-induced defects work as tunneling barriers; M. Suzuki et al., Appl. Phys. Lett. 81 (2002) 2273 • Self-irradiation with 100 eV C+ ions: nanotube-amorphous diamond composites; H. Schittenhelm, et al., Appl. Phys. Lett. 81 (2002) 2097. • Enhancement of the field emission after Ar ion irradiation; • Doping, tailoring of electrical properties; functionalization, etc. D.-H. Kim, et al., Chem. Phys. Lett. 378 (2003) 232. B. Wei et al., APL, 83 (2003) 3581; B. Ni et al., Appl. Phys. A 105 (2001) 12719.

  7. Our simulation methods • Molecular dynamics simulations to study nanotube properties and production of defects in nanotubes under irradiation. • Force models (to calculate the atomic structure): • Tersoff’s, Brenner’s, Marks’, Stuart’s empirical potentials for carbon; • Density-functional non-orthogonal tight binding (Frauenheim’s parametrization), orthogonal tight-binding (Xu’s model); • Ab initio methods (DFT, PW, GGA, etc., VASP, CASTEP) • Tight-binding and ab initio methods for calculating the electronic structure of nanotubes.

  8. Ion irradiation-induced defects in nanotubes V • The most abundant defects in SWNTs are vacancies. • Carbon atoms absorbed on nanotube walls (adatoms) play the role of interstitials. V COSIRES2002 A A A. Krasheninnikov et al., Phys.Rev. B 63 (2001) 245405. A. Krasheninnikov et al., Appl.Phys.Lett. 81 (2002) 1101. J. Pomoell et al., J. Appl. Phys. (2004) accepted. E. Salonen et al., NIMB. 193 (2002) 603.

  9. Mechanical properties of irradiated nanotube bundles: inter-tube covalent bonds vs vacancies E - the Young’s modulus ~ 1 Tpa; G - shear modulus < 10 MPa G0, Eb ~ G G, Eb ~ E A. Kis et al.,Nature Materials3 (2004) 153.

  10. Ion irradiation Welding of nanotubes using an ion beam COSIRES2002 Krasheninnikov et al. Phys. Rev. B 66 (2002) 245403.

  11. Ion-beam welding: experimental realization M.S. Raghuveer et al. Appl. Phys. Lett 48 (2004) 4484. Zh. Wang et al. Physics Letters A 324 (2004) 321.

  12. Protons (H+), GeV – range, theoretical estimate. V.M. Biryukov, S. Bellucci, Phys. Lett. B 542 (2002) 111. ? Channeling of energetic particles through nanotubes What about heavy ions? A conduit for energetic ions? Application: the solid state quantum computing (the Kane’s model), How can we make such a device in practice?

  13. MWNTs as apertures and conduits for energetic ions A. Krasheninnikov, and K. Nordlund, to be submitted. Collisions of heavy ions (Ar) with the inner shell MD simulations: Brenner potential for C-C; ZBL for Ar –C. The upper limit on ion energy

  14. MWNTs as apertures and conduits for energetic ions Fit to the MD simulation data: Continuum theory equation: The continuum theory works well here due to the open atomic structure of nanotubes

  15. MWNTs as apertures and conduits for energetic ions Channeling is possible even through bent tubes! Stability: a m-long tubes can survive shooting ~ 100 ions.

  16. Suggestions for the experimental setup metal Substrate • Ion beam aperture; • Beam steering on the nanoscale. “Technological part” – J. Nygard and D. Cobden, Appl. Phys. Lett. 79 (2001) 4216. Challenge for experimentalists?

  17. Magnetism in all-carbon systems • Magnetism has experimentally been observed in various all-carbon materials. • fullerenes (T. L. Makarova, et al., Nature 413 (2001) 716); • graphite (P. Esquinazi et al., Phys. Rev. B 66 (2002) 024429); • some other systems. • Magnetism is associated with defects (under-coordinated atoms); A. Andriotis et al., Phys. Rev. Lett. 90 (2003) 026801; Y.-H. Kim et al., Phys. Rev. B 68 (2003) 125420. • Irradiation can check the defect-mediated magnetism conjecture!

  18. H and He irradiation of graphite: effects on magnetic properties Experiment: P. Esquinazi et al., Phys. Rev. Lett. 91 (2003) 227201. 1.5 MeV H  relatively strong ferromagnetic signal; 2.25 MeV He weak signal just above the background. What is the mechanism? Why such a difference?

  19. Magnetic properties of defects • Interstitials (adatoms): magnetic but mostly annihilate P. Lehtinen et al., Phys. Rev. Lett. 91 (2003) 17202 . • Carbon interstitials clusters: even number of atoms: zero magnetic moment; odd number: quickly decaying moment. • Vacancies: are likely magnetic at T = 0; nonmagnetic at T = 300K. M ~ 1 B

  20. Dose theory experiment Magnetic properties of H-vacancy complexes • H-vacancy defects (DFT,VASP): • Stable • Suppress C i-v annihilation • H2 can hardly form • Magnetic M ~ 2.3 B Msample ~ dose  M 3 C 0.4emu 0.3 emu 10 C 1.4emu 1 emu Explanation for the experiment! Nanotubes irradiated with H can also be magnetic! P. Lehtinen et al., Phys. Rev. Lett. (2004) in press.

  21. Conclusions: • Atomistic simulations provide an insight into irradiation effects in carbon nanotubes; • There is qualitative and even quantitative agreement between experiments and the theory, theoretical predictions have been confirmed by experiments. • Irradiation of nanotubes can be used in a “beneficial” way to create new devices and tailor the nanotube properties

  22. Some more info on the subject Based on: A. Krasheninnikovet al.,Phys. Rev. B 63, 245405 (2001); A. Krasheninnikovet al.,Appl. Phys. Lett. 81, 1101 (2002); A. Krasheninnikovet al.,Phys. Rev. B 65, 165423 (2002); A. Krasheninnikovet al.,Phys. Rev. B 66, 245403 (2002); P. Lehtinen et al.,Phys. Rev. Lett. 91, 017202 (2003); + 15 other publications. A. Krasheninnikovet al.,Phys. Rev. B 69, 73402 (2004); M. Huhtala et al.,Phys. Rev. B 69 (2004) in press; P. Lehtinen et al.,Phys. Rev. Lett. 93 (2004) in press; Short review article: A. Krasheninnikov, K. Nordlund, NIMB 216 (2004) 355. http://www.acclab.helsinki.fi/nanotubes/

More Related