Web Release Date: May 16,
Diameter-Dependent Elastic Modulus Supports the Metastable-Catalyst Growth of Carbon Nanotubes
,
and
szló Forró*
Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Physics of Complex Matter, 1015 Lausanne, Switzerland, and Department of Materials, Oxford University, Parks Road, Oxford OX1 3PH, Great Britain
Received March 2, 2007
Revised April 25, 2007
Abstract:
We measured the elastic modulus of individual multiwalled carbon nanotubes (MWCNTs) grown by catalytic chemical vapor deposition (CVD) over a broad diameter range (10-25 nm). Alternating current (ac) dielectrophoresis was used for efficient tube deposition, and atomic force microscope (AFM) force-displacement curve technique was used for stiffness measurements. The elastic modulus exhibits a strong diameter dependence, showing a difference of nearly 2 orders of magnitude in the 10-20 nm diameter range (thinner MWCNTs have higher elastic modulus). Our results support the metastable-catalyst model in which the catalyst's molten skin plays a key role.
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