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STEM Observation and EELS Analysis of Dopant and Catalyst Particles in Carbon Nanotubes

Published online by Cambridge University Press:  02 July 2020

X. Fan
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN37831 Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, KY40506
E.C. Dickey
Affiliation:
Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky, KY40506
A.A. Puretzky
Affiliation:
Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN37996
D.B. Geohegan
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN37831
S.J. Pennycook
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN37831
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Doping carbon nanotubes with either electron donors or acceptors can improve their electrical conductivity [1-2]. In order to fully understand the doping mechanisms and the corresponding changes in the electronic properties, it is essential to reveal the spatial distribution of the dopants within the carbon nanotubes. In this study we have investigated both iodine- and bromine-doped single wall carbon nanotubes(SWNT) by Z-contrast scanning transmission electron microscopy (STEM). The SWNT bundles were made by arc-discharge method and doped with either molten iodine or bromine vapor. Both iodine and bromine were incorporated linearly within the nanotube bundles as shown in Fig. l and Fig.2 respectively. Higher resolution images of iodine doped nanotubes reveals that two iodine atomic chains are inside each individual SWNT as shown in Fig. lc. This unexpected result is contrary to the common belief that dopants can only enter interstitial site of the SWNT bundles.

Type
Sir John Meurig Thomas Symposium: Microscopy and Microanalysis in the Chemical Sciences
Copyright
Copyright © Microscopy Society of America

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References

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5. This research was sponsored by the NSF-MRSEC Advanced Carbon Materials Center under grant No. DMR- 9809686, and by the Division of Materials Sciences, U.S. Department of Energy, under contract DE-AC05- 96OR22464 with Lockheed Martin Energy Research Corp and the Laboratory-Directed Research and Development Program at ORNL.and by an appointment to the ORNL postdoctoral research program administered jointly by ORNL and ORISE.Google Scholar