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Inqui r y I s sue
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| 2016
Inqui r y I s sue
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| 2016
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B Y S T E V E K A R S J E N
waste and municipal solid waste. Since these potential
feedstocks are distributed, modular reactor designs offer the
potential for economically converting them into useful fuels
and chemicals.
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Learning how these materials behave is paramount.
Because 2D materials are all surface with no bulk, a host
of unique nanoscale properties—chemical, magnetic,
electronic, optical, and thermal—can be attributed to them.
“There’s a rule book for the properties of bulk, or three-
dimensional materials—and it contains big chunks that
are universally understood and accepted,” said Thiel, a
physical chemist, materials scientist, and Distinguished
Professor at Iowa State University. “But the rule book for
2D materials is largely unwritten. There are lots of things
we don’t know. We get lots of surprises, and then we must
explain them.”
Writing the rule book to the behavior of these materials
is only the first step in a larger goal; creating tunable
materials that could be potentially useful in a host of
tech applications, including ultrafast microelectronics,
catalysis, and spintronics.
It’s the reason that Thiel’s and Tringides’ research has
focused upon growing metals on 2D substrates over the
last four years, turning it into a major strength of Ames
Laboratory’s materials research.
Graphene has gained a lot of enthusiastic attention in
both scientific research and the tech industry because
electrons travel very fast along its surface, explained
Tringides. But to create functional devices, it necessitates
patterns of nanoscale-size metal contacts on its surface,
designed specifically for a desired function.
“Whatever material we are trying to create, uniformity
of the surface is the key to a functional device, and that
is where our ‘perfect’ research comes in. That perfection
makes us slow, but it’s a trade-off,” said Tringides. “If we
can gain a thorough understanding of how these contacts
can be produced under ideal conditions in a controlled
environment, then these methods can be optimized
eventually for commercial production and use.”
Thiel and Tringides’ most recent success is the
intercalation of dysprosium onto graphite layers.
Intercalation is the introduction of a material into
compounds with layered structures. That’s a real challenge
with graphite, since its purely 2D surface results in “slick”
layers with no good way to form bonds between them.
“It’s like a stack of blankets on a bed,” said Thiel.
“The blankets themselves are structurally sound, but two
blankets stacked on top of each other slide around, slip off
the bed, and are easily peeled off in layers.”
But the team has recently discovered the conditions
under which they can create different types of intercalated
metal-and-graphite systems, bonding those sliding blankets
of material together two-dimensionally. It’s a promising
new way to form a thin coating of a metal protected by
a carbon skin, and could lead the way to materials with
unique magnetic or catalytic properties.
With such a narrowly focused and
highly controlled experimental focus
in basic science, it could be tempting
to assume that their research, like their
experiments, occurs in a vacuum. But
Thiel credits the success of surface
science at Ames Laboratory to the close collaboration of
varied research groups.
“Ames Laboratory is a fertile environment for surface
science experiments because we have the opportunity to
collaborate directly with many scientists in diverse areas
of expertise addressing the same problem from a different
viewpoint,” said Thiel, including specialists in photonic
band gap materials, optical physics, theory, and materials
fabrication. “While that collaboration model has been
adopted by other institutions and is the norm now, Ames
Lab’s intimate size and community culture really started
it all, and our achievements in surface science have
benefited greatly from it.”
Dysprosium was found to make triangular-shaped crystalline islands on
graphene. Characterizing the unique structures of materials grown on
2D surfaces helps researchers better understand their possible electron-
ic, magnetic, or catalytic properties.
“If we can gain a thorough understanding of how these
contacts can be produced under ideal conditions in a controlled
environment, then these methods can be optimized eventually
for commercial production and use.”
hen Cynthia Jenks talks about Ames
Laboratory’s scientific accomplishments in
inorganic chemistry, she’s quick to credit any
successes to the team of specialized scientists
who are part of the Laboratory’s Chemical and Biological
Sciences (CBS) program and the Division of Materials
Science and Engineering.
“Whether designing new nanomaterials, devising new
homogeneous catalysts, interfacing between homogenous
and heterogeneous catalysts, or developing ionic liquids, our
work involves scientists with a diverse skill set in inorganic
chemistry,” said Jenks, assistant director of Scientific Planning
and division director for Ames Laboratory’s CBS program.
Jenks said several CBS-based research projects are
generating interest from the scientific community. For
example, inorganic chemist Javier Vela is researching
ways to design more efficient solar cells using a family of
materials known as perovskites. Chemists Aaron Sadow
and Igor Slowing are working on a project to design more
energy-efficient catalysts using earth-abundant materials,
and solid-state chemist Gordon Miller is using theoretical/
experimental investigation to identify new organic materials
that show promising chemical and physical properties.
One project involving teamwork at Ames Laboratory is a
so-called “Big Idea.” This project, which includes scientists
and engineers at 12 DOE national laboratories, resulted
from a Big Idea Summit sponsored by the Department of
Energy in 2015. Ames Laboratory’s part includes finding new
catalytic technologies that can efficiently produce biofuels
from diverse waste streams, including industrial waste, farm
Cynthia Jenks
“When we all bring our expertise to bear on
scientific challenges... the result can often be
the creation of exciting new science.”