Revealing the impact of catalyst phase transition on carbon nanotube growth by in situ Raman spectroscopy.
The physical state of the catalyst and its impact on the growth of single-walled carbon nanotubes (SWNTs) is the subject of a long-standing debate. We addressed it here using in situ Raman spectroscopy to measure Fe and Ni catalyst lifetimes during the growth of individual SWNTs across a wide range of temperatures (500-1400 °C). The temperature dependence of the Fe catalyst lifetimes underwent a sharp increase around 1100 °C due to a solid-to-liquid phase transition. By comparing experimental results with the metal-carbon phase diagrams, we prove that SWNTs can grow from solid and liquid phase-catalysts, depending on the temperature.
Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA. rrao@honda-ri.com
Rahul
R
Rao
Neal
N
Pierce
David
D
Liptak
Daylond
D
Hooper
Gordon
G
Sargent
S Lee
SL
Semiatin
Stefano
S
Curtarolo
Avetik R
AR
Harutyunyan
Benji
B
Maruyama