Imaging the Elastic Properties of Coiled Carbon Nanotubes with Atomic Force Microscopy
| Autor: | C. Van Haesendonck, M. Ahlskog, E. Seynaeve, Antonio Fonseca, Alexander Volodin, Janos B. Nagy |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Nanotube
Materials science Silicon Scanning electron microscope Graphene General Physics and Astronomy chemistry.chemical_element Mechanical properties of carbon nanotubes Nanotechnology Young's modulus Carbon nanotube law.invention symbols.namesake chemistry law Microscopy symbols Composite material |
| Zdroj: | Physical Review Letters. 84:3342-3345 |
| ISSN: | 1079-7114 0031-9007 |
| DOI: | 10.1103/physrevlett.84.3342 |
| Popis: | Coiled carbon nanotubes were produced catalytically by thermal decomposition of hydrocarbon gas. After deposition on a silicon substrate, the three-dimensional structure of the helix-shaped multiwalled nanotubes can be visualized with atomic force microscopy. Helical structures of both chiralities are present in the nanotube deposits. For larger coil diameters ( .170 nm), force modulation microscopy allows one to probe the local elasticity along the length of the coil. Our results agree with the classical theory of elasticity. Similar to the case of straight nanotubes, the Young modulus of coiled multiwalled nanotubes remains comparable to the very high Young modulus of hexagonal graphene sheets. ations in the elastic response of the coils along their length. Our results nicely agree with the classical theory of elas- ticity. From our FMM measurements we infer a Young modulus around 0.7 TPa for the coiled MWNTs. This re- sult is consistent with the reported high values of Young's modulus for straight carbon nanotubes which has been measured via resonant motion (8,9) of free standing tubes as well as via AFM induced deformations of nanotubes de- posited on a flat surface (10) or on substrates containing micropores (11). The nanotube material containing the helical MWNTs is produced by catalytic decomposition of acetylene, carried out at 700 ± C in a flow reactor at atmospheric pressure (12). The purified carbon nanotube material is sonicated at low power in isopropanol and is deposited onto a piece of an oxidized silicon wafer with gold markers fabricated by combining electron beam lithography and lift-off techniques. The nanotube deposits are first imaged with a scanning electron microscope (SEM: Philips, XL-30 FEG), allowing one to record the position of the coiled structures. Next, the AFM imaging and the FMM measurements are performed in air with a commercial system ( Park Scientific Instruments, M5) using silicon cantilevers with a tip apex radius of curvature of about 10 nm. The elastic response of the coiled nanotubes can be probed locally with the FMM technique (7) which is illustrated in Fig. 1(a). The Si cantilever is gently tapping the sample surface at the cantilever resonance frequency fres 98 kHz with an amplitude ranging between 0.2 and 5 nm. Additionally, the vertical position of the sample is periodically modulated at a much smaller frequency fmod in the range 8 11 kHz with a modulation amplitude between 1 and 2 nm. Harmonic detection at the frequency fmod of the periodically varying interaction between tip and coiled nanotube enables one to locally probe its elasticity. |
| Databáze: | OpenAIRE |
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