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Title: Micro glow plasma for localized nanostructural modification of carbon nanotube forest

Abstract

This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ∼30% and ∼300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.

Authors:
; ; ; ;  [1]
  1. University of British Columbia, Vancouver, British Columbia V6T 1Z4 (Canada)
Publication Date:
OSTI Identifier:
22590479
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ARGON; ATMOSPHERIC PRESSURE; CARBON NANOTUBES; CURRENTS; DESIGN; ELECTRODES; EQUIPMENT; MODIFICATIONS; PLASMA; POTENTIALS; SURFACES; TUNGSTEN

Citation Formats

Sarwar, Mirza Saquib us, Xiao, Zhiming, Saleh, Tanveer, Nojeh, Alireza, and Takahata, Kenichi. Micro glow plasma for localized nanostructural modification of carbon nanotube forest. United States: N. p., 2016. Web. doi:10.1063/1.4961629.
Sarwar, Mirza Saquib us, Xiao, Zhiming, Saleh, Tanveer, Nojeh, Alireza, & Takahata, Kenichi. Micro glow plasma for localized nanostructural modification of carbon nanotube forest. United States. doi:10.1063/1.4961629.
Sarwar, Mirza Saquib us, Xiao, Zhiming, Saleh, Tanveer, Nojeh, Alireza, and Takahata, Kenichi. 2016. "Micro glow plasma for localized nanostructural modification of carbon nanotube forest". United States. doi:10.1063/1.4961629.
@article{osti_22590479,
title = {Micro glow plasma for localized nanostructural modification of carbon nanotube forest},
author = {Sarwar, Mirza Saquib us and Xiao, Zhiming and Saleh, Tanveer and Nojeh, Alireza and Takahata, Kenichi},
abstractNote = {This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ∼30% and ∼300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.},
doi = {10.1063/1.4961629},
journal = {Applied Physics Letters},
number = 8,
volume = 109,
place = {United States},
year = 2016,
month = 8
}
  • Here, the properties of carbon nanotube (CNT) networks and analogous materials comprising filamentary nanostructures are governed by the intrinsic filament properties and their hierarchical organization and interconnection. As a result, direct knowledge of the collective dynamics of CNT synthesis and self-organization is essential to engineering improved CNT materials for applications such as membranes and thermal interfaces. Here, we use real-time environmental transmission electron microscopy (E-TEM) to observe nucleation and self-organization of CNTs into vertically aligned forests. Upon introduction of the carbon source, we observe a large scatter in the onset of nucleation of individual CNTs and the ensuing growth rates.more » Experiments performed at different temperatures and catalyst particle densities show the critical role of CNT density on the dynamics of self-organization; low-density CNT nucleation results in the CNTs becoming pinned to the substrate and forming random networks, whereas higher density CNT nucleation results in self-organization of the CNTs into bundles that are oriented perpendicular to the substrate. We also find that mechanical coupling between growing CNTs alters their growth trajectory and shape, causing significant deformations, buckling, and defects in the CNT walls. Therefore, it appears that CNT–CNT coupling not only is critical for self-organization but also directly influences CNT quality and likely the resulting properties of the forest. As a result, our findings show that control of the time-distributed kinetics of CNT nucleation and bundle formation are critical to manufacturing well-organized CNT assemblies and that E-TEM can be a powerful tool to investigate the mesoscale dynamics of CNT networks.« less
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  • We have shown that the sensitivity of carbon nanotube (CNT) based sensors can be enhanced as high as 74 times through surface modification by using the inductively coupled plasma chemical vapor deposition method with oxygen. The plasma treatment power was maintained as low as 10 W within 20 s, and the oxygen plasma was generated far away from the sensors to minimize the plasma damage. From X-ray photoelectron spectroscopy analysis, we found that the concentration of oxygen increased with the plasma treatment time, which implies that oxygen functional groups or defect sites were generated on the CNT surface.
  • Carbon nanotubes (CNTs) have unique chemical and physical properties. Herein, we report an XPS analysis of a forest of multiwalled CNTs using monochromatic Al Kα radiation. Survey scans show only one element: carbon. The carbon 1s peak is centered 284.5 eV. The C 1s envelope also shows the expected π → π* shake-up peak at ca. 291 eV. The valence band and carbon KVV Auger signals are presented. When patterned, the CNT forests can be used as a template for subsequent deposition of metal oxides to make thin layer chromatography plates.1-3