AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Thin Film Deposition of Self-assembled Carbon Nanotubes
Jean de La Verpilliere, ADAM M BOIES, University of Minnesota
Abstract Number: 722 Working Group: Nanoparticles and Materials Synthesis
Abstract For properties of carbon nanotubes (CNTs) to be transferred into commercial products, control of the organisation at the nano, micro, and macro scales needs to be controlled. Gas-phase processes are inherently scalable, while the power of self-assembly allows for a precise control of the final structure at the microscale and nanoscale. The present work proposes a novel illustration of this concept: so-called self-assembled CNT sea urchins are synthesized (Kim 2010), and continuously deposited on a substrate. The resulting nanomaterial presents interesting properties in terms of nanostructure, porosity, electrical and thermal conductivity. Properties of the final material being largely influenced by particle deposition parameters.
An aqueous solution of Al(NO3)3 and Fe(NO3)3 was atomized in a nitrogen flow using a nebulizer. Upon droplet evaporation in a drier, both metallic salts precipitate, forming spherical nanoparticles with an aluminium-enriched surface consisting of small iron nitrate patches in an aluminium nitrate matrix. A first tube furnace thermally decomposes the metal nitrates in a reducing atmosphere, thus producing Al-Fe nanoparticles. These nanoparticles form the core of the CNT sea urchins that are grown in a subsequent step, whereby a carbon source catalytically decomposes on the iron at the surface of the particles in another furnace, enabling CNT growth. Characterisation was performed in order to optimize the process to synthesize a high density of small diameter, long, straight CNTs on the surface of the cores. A thermophoretic precipitator allowing for high-efficiency controlled thin film deposition on a silicon wafer over a 5 cm2 area was designed with the help of three dimensional simulations on COMSOL Multiphysics®. Theoretical and experimental deposition efficiencies and uniformities are compared. The thermophoretic precipitator was then used to deposit thin films of CNT sea urchins. Preliminary characterisation of the resulting thin films is discussed.