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by Gaylon Cox
While nanowires are relatively new in the world of science, their
unique mechanical, electrical, and optical properties make great
research candidates. Researchers such as Jonathan Zimmerman, a
Principal Member of Technical Staff at Sandia National Laboratories,
are learning more about the inherent potential of these miniature wires.
Nanobridge formation in Gold
nanowires - stretching of nanowires to specific strains results in
tailored multishell structures that are ideally suited for manipulation
of biological molecules, high electrical conduction, and high strength
nanocomposites.
Nanowires are very tiny wires with dimensions of the order of a
nanometer (10^9 meters). They are composed of metals such as silver,
gold, or iron, or semiconductors such as silicon, zinc oxide, and
germanium. Nanowires are not found in nature, so to perform research on
them, they must first be fabricated in the lab.
Nanowires have the potential to aid in the next generation of
electronic devices and computer components. Current research suggests
that nanowires may soon be used to greatly enhance the capabilities of
transistors, memory devices, and sensors.
Nanowire properties are greatly affected by the shape and structure of
the wire if it is mechanically deformed. This is where Zimmerman’s
research comes in. He performs simulations to predict how nanowires
deform, when they fail and through which physical mechanisms, and how
nanowire geometry influences this failure process. Zimmerman’s research
provides the information necessary to efficiently implement nanowires
in sensors and other microelectronic devices that are needed within
Sandia’s systems.
With national security riding on his results, Zimmerman
must use efficient methods to not only perform simulations, but to also
display their results in the most useful manner. He has to make
absolutely sure he is using the right tools for the job.
Using the Right Tools
Zimmerman’s various research projects have been aided by EnSight for
over 7 years. Most recently, EnSight has helped him to provide the
results of his nanowire simulations. Zimmerman uses specialized code,
including ParaDyn and LAMMPS, to perform the nanowire simulations. He
then uses EnSight to visualize and analyze his simulation results.
Using EnSight, he is able to demonstrate the properties of nanowires,
as well as provide 3D renderings of the results. With EnSight, he can
illustrate if or how a nanowire deforms under certain conditions.
Zimmerman said, “Our goal is to demonstrate the mechanics of nanowires
under various conditions in order to develop a predictive understanding
of nanowire behavior.”
“By being able to demonstrate the failure processes of the deformation
of nanowires, we can better understand how and when to properly
manipulate them for more efficient usage in a variety of technologies.”
An Atomistic Approach
Since many aspects of nanowires are not yet well understood, cutting
edge techniques are being developed to study their behavior.
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Shape
Memory Effect in Copper nanowires – stress-induced reorientation at low
temperature (10K); load removal at low temperature; deformation undone
at high temperature (>425K). |
Zimmerman performs atomistic simulations and uses EnSight to provide a
glimpse into the mechanical behavior and deformation mechanisms of
nanowires.
Atomistic simulation, the computer modeling of defects in materials at
the microscopic level, allows Zimmerman to verify fundamental
characteristics of nanowires and how they are influenced by certain
conditions.
With EnSight, Zimmerman is able to show how factors such as different
tension and compression levels affect nanowires at the molecular level.
“Atomistic simulations enable us to quantify the strengths of these
wires during tensile failure, discover the mechanisms responsible for
mechanical failure, and determine how wire dimensions, loading rates,
crystal orientation and material models impact these characteristics.
EnSight helps us to easily visualize our results.”
Presenting the Results
The ability to fine-tune the results makes EnSight a great match for
Zimmerman’s research. To be able to customize the look and feel of his
results depending on the presentation method and audience makes the
results that much more valuable.
“Sometimes, I need to isolate and show just certain aspects of the
failure process. For example, I often need to display only items
according to their value of strain (or stress).”
EnSight also allows Zimmerman to color his results based on specified
parameters. Color coding makes it easy to quickly pinpoint and
reference specific areas when presenting the results.
Nanobridge
formation in Gold nanowires - stretching of nanowires to specific
strains results in tailored multishell structures that are ideally
suited for manipulation of biological molecules, high electrical
conduction, and high strength nanocomposites.
“I also like the fact that I can rotate the generated results and that
I can make movies that show the nanowire structure from various
perspectives. This way, the viewer can really understand what physical
processes are occurring during the nanowire deformation.”
Zimmerman uses his EnSight-produced graphics in scientific papers, on web sites, and for presentations.
“EnSight adds a level of quality and understanding to my research,
thereby allowing the results to be accessible by a wider audience.”
More Information
The exciting and relatively new field of nanowire research promises to
produce vital information on how nanowires can best be used in a wide
range of applications.
Additional resources and case studies:
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