ORCID Profile
0000-0001-5911-9418
Current Organisation
Université de Strasbourg
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Publisher: Wiley
Date: 26-11-2009
Publisher: American Chemical Society (ACS)
Date: 13-08-2009
DOI: 10.1021/NN900634F
Abstract: New methods of processing multiwall carbon nanotubes (CNTs) are demonstrated in experiments in the transmission electron microscope (TEM). These include precisely controllable cutting, repairing, and interconnecting of different CNTs with the assistance of an encapsulated Co particle. All processes involve the interactions between the metal and graphitic shells that are driven by combined electrical biasing [using a scanning-tunneling microscope (STM)-TEM setup] of the CNT and focused electron-beam irradiation of a Co-containing region. In particular, we present two CNT soldering processes, that is, Co-joined and Co-catalytic connections. The former process uses a Co particle as the central node to which two CNTs are covalently attached on the opposite sides, and the latter makes use of the segregation of new graphitic shells from the metal at the connecting site, resulting in CNT plumbing. We compare the mechanical robustness of both connection types by direct force measurements in the TEM using an integrated atomic force microscope (AFM) setup. They reveal a tensile strength of 4.2 and 31 GPa, respectively, thus demonstrating the superiority of the Co-catalytic connection whose strength is already comparable to standard CNTs. In addition, all connected nanotubes show metallic conduction. The developed methods could be of particular importance in future nanoelectronic device technology.
Publisher: Proceedings of the National Academy of Sciences
Date: 24-03-2009
Abstract: We report the controlled formation and characterization of heterojunctions between carbon nanotubes and different metal nanocrystals (Fe, Co, Ni, and FeCo). The heterojunctions are formed from metal-filled multiwall carbon nanotubes (MWNTs) via intense electron beam irradiation at temperatures in the range of 450–700 °C and observed in situ in a transmission electron microscope. Under irradiation, the segregation of metal and carbon atoms occurs, leading to the formation of heterojunctions between metal and graphite. Metallic conductivity of the metal–nanotube junctions was found by using in situ transport measurements in an electron microscope. Density functional calculations show that these structures are mechanically strong, the bonding at the interface is covalent, and the electronic states at and around the Fermi level are delocalized across the entire system. These properties are essential for the application of such heterojunctions as contacts in electronic devices and vital for the fabrication of robust nanotube–metal composite materials.
Publisher: Springer Science and Business Media LLC
Date: 10-1991
DOI: 10.1007/BF00357194
Publisher: Wiley
Date: 23-03-2010
Abstract: Multi‐walled boron nitride nanotubes were irradiated with low and medium energy argon and helium ions at room and elevated temperatures. The irradiated s les were characterized by transmission electron microscopy and Raman spectroscopy, and a comparison to the response of carbon nanotubes to irradiation was made. A dose of 2 × 10 15 ions/cm 2 was found to give rise to complete amorphization for irradiation with 40 keV Ar ions,while a comparable dose (in terms of displacement per atom) of 1.2 × 10 18 ions/cm 2 for 350 keV He caused significantly less damage. Elevated temperatures considerably reduce the amount of damage indicating that efficient annealing of defects occurs in BN nanotubes already at 300 0 C. Our results provide evidence that multi‐walled BN nanotubes have similar or even better stability under ion irradiation than their carbon counterparts. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
No related grants have been discovered for Florian Banhart.