Synthesis of Carbon Nanotubes Using Field Emission
We have designed a field emission microscope (FEM) coupled to a chemical vapor deposition (CVD) reactor in order to directly observe the growths of individual carbon nanotubes (CNTs) from the nucleation stage. Catalyst metals are first deposited in situ on a sharp metallic tip during direct FEM imaging and formed into nanoparticles by dewetting. CNTs are then grown directly on these nanoparticles by CVD in acetylene at appropriate temperatures (600–900 °C). The FEM patterns are formed by electrons emitted from individual CNT caps. The videos are analyzed to extract the growth rates and models. In situ field emission I/V measurements are also performed. The most interesting new discovery is that the CNTs often rotate axially during growth, thus showing a full compatibility with a recently proposed model of 'screw-dislocation-like' (SDL) mechanism. The event is not rare as four rotating CNT growths versus six non-rotating growths were observed. In one case the CNT rotated quite uniformly ∼180 times during its 11 min growth. This observation should aid researchers to better understand and control the growth of SWNTs.
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Document Type: Short Communication
Publication date: February 1, 2011
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- Nanoscience and Nanotechnology Letters (NNL) is a multidisciplinary peer-reviewed journal consolidating nanoscale research activities in all disciplines of science, engineering and medicine into a single and unique reference source. NNL provides the means for scientists, engineers, medical experts and technocrats to publish original short research articles as communications/letters of important new scientific and technological findings, encompassing the fundamental and applied research in all disciplines of the physical sciences, engineering and medicine.
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