78th Annual Meeting of the Southeastern Section of the APS
Volume 56, Number 9
Wednesday–Saturday, October 19–22, 2011;
Roanoke, Virginia
Session BB: Nano Materials
8:30 AM–10:30 AM,
Thursday, October 20, 2011
Room: Crystal Ballroom B
Chair: Michel Pleimling, Virginia Polytechnic Institute and State University
Abstract ID: BAPS.2011.SES.BB.4
Abstract: BB.00004 : Synthesis of nanostructures by combination of electrospinning and sputtering techniques*
10:00 AM–10:30 AM
Preview Abstract
Abstract
Author:
Wilfredo Ota\~no
(University of Puerto Rico at Cayey)
Electrospinning and sputtering are well known techniques for the
formation of different materials in the shape of fibers and
films, respectively. Both techniques offer the advantage of being
able to prepare a broad range of materials, from metals to
insulators, in a different range of compositions and structures.
Their combined used offers then a unique opportunity to explore
the fabrication of different materials with tailored compositions
and nanostructures. An interesting application results when the
electrospun fibers are used as templates for sputtering of
palladium metal. Palladium (Pd) is one of the most prominent
materials studied for the detection of hydrogen gas. Hydrogen
rapidly dissociates on its surface and diffuses into subsurface
layers forming palladium hydride with consequent changes in
optical, mechanical and electrical properties that are easily
detected. Materials with nanoscale morphologies are promising to
improve sensor performance as they provide large surface areas
for adsorption, and smaller crystallite size reducing the time
needed for ``bulk'' diffusion. In this presentation it will be
shown how Pd nanoribbons and nanoshells are prepared by magnetron
sputtering deposition on top of the mat of polymer fibers.
Sputtering is a line-of-sight deposition process and the fibers
become a variable angle-substrate for the incoming Pd flux. A
larger amount of palladium is deposited on top of the fiber where
the incoming flux is perpendicular to the surface compared to the
sides where the flux is incident at a glancing angle. The top and
sides of the fibers shadow their bottom parts closer to the
substrate preventing any substantial deposition there. The end
result of the deposition is the formation of Pd nanostructures,
thicker in the middle region than at the edges, with a large void
network. The high sensitivity and response time shown to 1\% or
less of hydrogen in nitrogen is understood to result from the
reduced dimensions combined with this unique nanostructure. A
description will be given of the conductance changes with
hydrogen concentration as result of the competing mechanisms of
percolation and scattering.
*Author Acknowledges support of NASA NNX08BA48A and NSF 1002410 grants.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.SES.BB.4