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Volume 3
Recycling 2019 & Material Science 2019
July 22-23, 2019
Page 14
Material Science and Nanotechnology
Global Recycling Summit
July 22-23, 2019 | Rome, Italy
6
th
International Conference on
&
Journal of Environmental Geology
Virginia M Ayres
Michigan State University, USA
Nanowires and Nano-enhanced Properties: What Proofs are Definitive?
T
he implications of nanotechnology are wide-ranging and include medicine, military applications, computing, and
astronomy. There is therefore growing recognition of the importance of nurturing a community of scientists and
engineers with the necessary skill set(s) needed to establish definitive proof that nanostructures and/or nano- enhanced
properties are present. In the present discussion, the combinations required to establish two new discoveries in
semiconducting and metallic nanowires will be presented. The first investigation details our contributions to recognition
that gallium nitride nanowires, which are candidates for nanoelectronics and nanowire lasers, have interior structures that
will affect their performance. An initial key observation of new “biphasic” wurtzite/zinc-blende crystalline homostructure
with a sharp phase transition of 1-3 atomic layers emerged unexpectedly during a high resolution transmission electron
microscopy (HRTEM) investigation of nanowires grown at 850oC. Initial “proofs” came from electron diffraction and
cathodoluminescence studies that yielded unambiguous evidence for two different crystal structures and energy bandgaps,
but additional HRTEM of focused ion beam cross sections was required to replace “biphasic” with the correct “nanowires
within a nanowire” internal structure. Furthermore, the internal structure proved to be synthesis temperature-dependent,
with an abrupt change to pure wurtzite and unanticipated internal nanopipes at 1000oC. The nanopipes identified the
growth mechanism, as well as provided information for device designs. The second is an ongoing investigation of highly
crystalline nickel, cobalt and alloy nanowires, which have multiple magnetic and optical sensing, and also biomedical,
applications. Once again, there was an initial key observation of an unexpected result: areas of well-formed ~40-80 nm
nanowires discovered during an atomic force microscopy investigation of a nanocrystalline film surface. Extensive use of
recently available high resolution scanning electron microscopy with selected area energy dispersive X-ray spectroscopy
demonstrated that the new regime of high-speed turbulent flow electrodeposition coupled with a thin hydrocarbon layer
on the surface produced carbon nanowire-catalyst particles in metallic ion “gas” environment, while HRTEM confirmed
crystallinity that exceeds current state of the art in anodized template synthesis.
Biography
Virginia M Ayres earned the Ph.D. and M.S. in Physics from Purdue University, and B.A.’s in Physics and Biophysics from Johns Hopkins
University. She is currently an Associate Professor in the Department of Electrical & Computer Engineering at Michigan State University,
where she heads the Electronic and Biological Nanostructures Laboratory. Professor Ayres is the recipient of numerous NSF, NASA and
international awards that support ongoing research in nanoelectronics and nanobiophysics. She is honored to be the recipient of awards as
a Chair of International Cooperation at Tokyo Institute of Technology and as a Distinguished Women Scholar and a Department of Physics
Outstanding Alumna from Purdue University.
ayresv@msu.eduVirginiaMAyres
,JEnvironGeol. |Volume3
ISSN:2591-7641