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Power of dynamic observations in understanding the role of catalyst in the synthesis of carbon nanotubes and nanowires
When: Thursday, 1st October, 2009, 14:00
Where: Ground Floor Seminar Room, Building 311, DTU
Speaker: Renu Sharma
Arizona State University & NIST, USA
ABSTRACT
Nanotubes and nanowires are fundamental building blocks for nanotechnology. Catalysis plays an important role in the nucleation and growth of these 1-D nanostructures. Most of them are
synthesized using chemical vapor deposition process where catalyst activates the decomposition of the precursor molecule and/or acts as nucleation site. Transmission electron microscopy (TEM)
techniques are often employed to evaluate the effect of the cathalyst nature and reaction conditions on the structure and morphology of the nanotubes and nanowires formed. However, in order to
elucidate the exact function of the catalyst during nucleation and growth, we need to make dynamic observations under the reaction conditions. Fortunately, recent developments in TEM
instrumentation have made it possible to observe gas-solid interactions under reaction conditions. Such instruments are now commercially available as environmental scanning/transmission electron microscopes or ESTEM. At Arizona State University, we have been using this technology to understand the nature and role of catalyst for the growth of carbon nanotubes and nanowires (e.g.
Si, Ge and GaN). We have taken advantage of the small probe size (~0.2 nm) of Tecnai F-20 FEG to selectively synthesize model catalysts by electron beam induced decomposition of metal-organic
precursor, for CNT growth. These experiments have provided valuable insight of the nucleation and growth processes as well as for suitable reaction conditions for selective synthesis
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