Bulletin of the American Physical Society
2007 APS Four Corners Section/SPS Zone 16 Joint Fall Meeting
Volume 52, Number 14
Friday–Saturday, October 19–20, 2007; Flagstaff, Arizona
Session K1: Carbon Nanotubes |
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Chair: Heinz Nakotte, New Mexico State University Room: Chemistry (Bldg. 20) Room 224 |
Saturday, October 20, 2007 2:00PM - 2:12PM |
K1.00001: Carbon nanotubes and graphene: their growth in a low temperature chemical reaction Elisabeth Strein The synthesis of carbon nanotubes and graphene sheets is typically done at temperatures between 500-2000 $^{\circ}$C with chemical vapor deposition techniques. Our research concerns synthesis in a catalytic organometallic reaction that takes place at 110 $^{\circ}$C. To determine the reaction mechanism, time lapsed samples of the reaction of iron bis (cyclooctatetraene) and dimethyl sulfoxide with dimethoxyethane were extensively studied with an AFM. Data is presented for the graphene sheets and for the growth of tubes in the reaction. Results from TEM and Raman data are discussed [Preview Abstract] |
Saturday, October 20, 2007 2:12PM - 2:24PM |
K1.00002: Coated Carbon Nanotube Scaffolding as a Cheap Alternative to Deep Si Etching David Hutchison, Brendan Turner, Robert Davis, Richard Vanfleet Deep silicon etching is a process to create high aspect ratio vertical structures. It requires expensive equipment and is chemically specific to Si. We demonstrate a cheaper, easier, and more general method of creating comparable structures. Vertically-aligned carbon nanotubes (VACNTs) are grown using chemical vapor deposition (CVD) into high aspect ratio structures. The spaces between nanotubes are then filled with various materials by low-pressure CVD. To date, we have filled in our structures with Si and amorphous carbon, achieving features down to 1$\mu$m in size, but this method also appears generalizable to a wide variety of materials. The VACNT structures are grown from a patterned, evaporated Fe film on a diffusion barrier layer. Using transmission electron microscopy, we show that without the barrier layer, during annealing, the Fe forms a silicide with the underlying silicon so that it cannot work effectively as a catalyst for nanotube growth. The effectiveness of various barrier layers in stopping iron silicide formation is compared by SEM and TEM analysis of the substrate and resulting tubes. Alumina is shown to be the best barrier layer to grow high aspect ratio VACNTs. [Preview Abstract] |
Saturday, October 20, 2007 2:24PM - 2:36PM |
K1.00003: Optimized Growth of Patterned Vertically-aligned Carbon Nanotube Forests Brendan Turner, David Hutchison, Matthew Carter, Richard Vanfleet, Robert Davis Vertically-aligned carbon nanotube (VACNT) forests can provide inexpensive templates for a variety of high aspect ratio structures. We report Chemical Vapor Deposition (CVD) growth of VACNT structures from thin patterned Fe films. We will present the effect of Fe film thickness, growth temperature, gas concentrations, and other parameters on VACNT growth rate, tube size, density, and dimensional control of patterned vertical structures. Analysis was done by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). [Preview Abstract] |
Saturday, October 20, 2007 2:36PM - 2:48PM |
K1.00004: Gas Absorbtion and Interaction Inside Carbon Nanotubes William Blackmore, Austin Buddy Davis, T. Randall Dillingham Since the discovery of carbon nanotubes in 1991 by S. Iijima the field of Nanoscience has grown in leaps and bounds. Potential applications include nanowires for quantum computers, hydrogen storage devices in fuel cells, biosensors and bioreactors, and much more. The focus of this research has been to improve upon existing etching techniques to ``unzip'' the nanotubes allowing improved absorption of introduced gaseous species and, once introduced, to prompt chemical interaction between multiple gaseous species in the nanotubes using XPS. Implications of this research could extend to safe transportation of volatile gasses, increased efficiency filtration, and more. To date, a mixture of HNO$_3$/H$_2$O$_2$ and H$_2$SO$_4$/H$_2$0$_2$ and an etching time of 1 week to a month has provided the best oxidation results while maintaining the structure of the carbon nanotubes. Initial spectra of trapped CO$_2$ have been completed and further experiments including multiple species are planned. [Preview Abstract] |
Saturday, October 20, 2007 2:48PM - 3:00PM |
K1.00005: Condensation of micro-grown vertically aligned carbon nanotube forests Katherine Barnett Similar to many materials made of fibers, carbon nanotube forests condense when they are saturated and dried. Previously larger-scale patterned nanotube forests have been shown to condense and form extremely thin, dense, vertical sheets of nanotubes. While larger features condense into patterned features readily, smaller features require more delicate shrinking conditions and are highly dependant on temperature, solvent type, solvent vapor density, and heating rate. By optimizing these parameters, I have been able to successfully condense nanotube forests so that they maintain their original patterns, they simply become thinner and denser. Shrinking features that are on the micrometer order of magnitude, allows us to use these larger patterns to get extremely small features. [Preview Abstract] |
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