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Nitrogen controlled iron catalyst phase during carbon nanotube growth


Type

Article

Change log

Authors

Bayer, BC 
Baehtz, C 
Kidambi, PR 
Weatherup, RS 
Mangler, C 

Abstract

jats:pClose control over the active catalyst phase and hence carbon nanotube structure remains challenging in catalytic chemical vapor deposition since multiple competing active catalyst phases typically co-exist under realistic synthesis conditions. Here, using in-situ X-ray diffractometry, we show that the phase of supported iron catalyst particles can be reliably controlled via the addition of NH3 during nanotube synthesis. Unlike polydisperse catalyst phase mixtures during H2 diluted nanotube growth, nitrogen addition controllably leads to phase-pure γ-Fe during pre-treatment and to phase-pure Fe3C during growth. We rationalize these findings in the context of ternary Fe-C-N phase diagram calculations and, thus, highlight the use of pre-treatment- and add-gases as a key parameter towards controlled carbon nanotube growth.</jats:p>

Description

Keywords

40 Engineering, 4001 Aerospace Engineering

Journal Title

Applied Physics Letters

Conference Name

Journal ISSN

0003-6951
1077-3118

Volume Title

105

Publisher

AIP Publishing
Sponsorship
European Research Council (279342)