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Honolulu, Hawaii, United States, 2006/11/02 - An electric-field-induced method to not only improve CNT uniformity but also to create a new approach to control the microstructure of CNTs.
Various methods have been developed for growing well-aligned CNTs based on variant alignment mechanisms such as 'overcrowding growth', 'template hindrance growth' and 'electric field induced growth'. Compared to other methods, electric field induced growth has been considered to be a more effective and controllable method for producing well-aligned single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Interestingly, while the alignment of CNTs became more controllable and repeatable with the assistance of an electric field, it was also shown that for CNTs grown in an electric field, the diameter uniformity and the crystallinity of graphite sheets of CNTs were clearly improved. This led Chinese researchers to develop an electric-field-induced method to not only improve CNT uniformity but also to create a new approach to control the microstructure of CNTs.
Generally, variant CNT microstructures determine their properties, for example, highly graphitized CNTs exhibit excellent mechanical and electrical properties; however, the CNTs with defects and poor crystallinity contribute to the field emission property and hydrogen storage capacity. Therefore, it is of vital importance to control the CNT microstructures effectively for desired applications.
Recently, for the purpose of growing CNTs with different microstructures and crystallinity, several methods have been attempted by changing growth parameters such as catalyst particle size, growth temperature, flow rate of carrier gas, plasma power and bias voltage, in a chemical vapor deposition (CVD) process.
"Compared to the regular arc discharge and CVD methods, our process provides an unique advantage for synthesizing carbon nanotubes in a simple experiment setup and investigating the effect of electric field on the growth of carbon nanomaterials" Professor Chunxu Pan from the Department of Physics at Wuhan University/PR China, explains to Nanowerk.
Read the full article on the Nanowerk website.
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By Michael Berger, Copyright 2006 Nanowerk LLC