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Inqui r y I s sue
1
| 2016
Inqui r y I s sue
1
| 2016
21
“If you want to do something like one of these ‘big ideas’,
it’s never going to be a single person who will be able to solve
these problems. It takes a team of scientists, from inorganic
chemists to engineers to those who understand separations
and modular design,” said Jenks. “When we all bring our
expertise to bear on scientific challenges and study the
foundations of the roadblocks to their success, the result can
often be the creation of exciting new science.”
MATERIALS SYNTHESIS
Ames Laboratory associate scientist Javier Vela’s research
focuses on the development of new optical nanomaterials,
heterostructures, and devices
for applications in catalysis,
energy conversion, and
biological imaging.
“In my laboratory, we’re
very good at making things, in
our case, nano-sized particles of different compounds,” said
Vela, who likens his work to that of a high end, scientific cook.
Like any good cook, Vela begins with raw materials, which
for him include different compounds, either crystalline or
molecular. Then he consults his toolbox of available reagents
and mixes in the appropriate amount of ingredients to make
the appropriate material. It sounds easy, but according to
Vela there’s little room for error.
“We have mastered the art of knowing how to combine
these reagents in the right proportions and under the right
set of conditions to achieve the desired materials in the
formulation andwith the right properties we’re interested in,”
said Vela, who is also an associate professor of chemistry at
Iowa State University. “In the world of synthetic chemistry,
whatever we make has to be reproducible; nothing can be
by luck.”
Recently, Vela’s group of synthetic inorganic chemists
has been cooking with two other Ames Laboratory and
ISU scientists, Emily Smith, analytical chemist, and Jacob
Petrich, ultrafast spectroscopist, who, like Vela, study
organo lead-halide perovskite semiconductors. These tiny
semiconducting optically active crystals are known to display
intriguing electronic, light-emitting, and chemical properties.
“My part of the work is to understand the synthesis issues
going on inside these perovskites, which has led to several
interesting phenomena,” said Vela. “With our increased
knowledge, we are developing a rational, predictable approach
to modify their structure and to enhance their properties to
make them better.”
Ultimately, Vela said, better organo lead-halide perovskites
could lead to better construction materials for solar cells with
20 percent solar power-conversion efficiency.
CATALYSIS
According to Ames Laboratory associate scientist Aaron
Sadow, much of today’s chemical manufacturing involves
catalysis—the acceleration of chemical reactions. Many
of these processes involve mixed-phase heterogeneous
catalysis, but Sadow said there are also a large number of
processes that use single-phase homogeneous catalysis,
most commonly solution-phase catalysts.
Sadow, who is also an ISU associate professor of
chemistry, has been partnering with computational
scientists at Ames Laboratory to understand what happens
at interfaces between liquids and catalytic solids.
“We’re trying to measure the
rates of reaction, understand
mechanisms and then use
those to guide site synthesis,”
Sadow said.
His group is involved in
cutting-edge research involving
the design of both homogeneous
and heterogeneous catalysts
using earth-abundant materials.
These materials, like zirconium
or magnesium, are cheaper and
more plentiful than commonly
used catalysts like platinum,
rhodium and palladium.
“The interesting thing for me
is these materials provide the
opportunity to access new mechanisms and new pathways,
and if we can understand those pathways, we can use these
earth-abundant metals in interesting processes that could
one day have an impact on industrial catalysis,” said Sadow.
INNOVATIVE AND COMPLEX METAL-RICH MATERIALS
Ames Laboratory associate scientist GordonMiller is both
a theorist and experimentalist, two diverse areas of expertise
he combines to identify new inorganic materials that show
promising chemical and physical properties.
“We concentrate on intermetallic compounds because
they are best suited for combined theoretical/experimental
investigations,” said Miller, who is also an ISU professor of
chemistry. “Theyalsoofferfundamentalopportunitiestowards
understanding relationships among chemical composition,
atomic structure, physical properties and chemical bonding
in materials due to their elegant complexity.”
Miller collaborates with scientists throughout the Ames
Laboratory, using a variety of synthetic approaches to produce
new materials and then characterizes their atomic structure
by X-ray diffraction. He also assesses possible chemical
substitutions that can lead to changes in structure and
properties. In this way, experiment
and theory are engaged synergistically
to yield new metal-rich materials.
Miller’s approach has led to
new magnetic refrigerants and
quasicrystals. His group’s most
recent work involves researching
cluster chemistry of intermetallic
compounds by introducing lithium,
research that has resulted in the
discovery of new complex structures
based on clusters of icosahedra,
and shows promise of yielding
unprecedented clusters in solids.
Miller feels his greatest outcome
has been the students and post
docs he’s helped teach to approach
scientific inquiry using both
experiment and inquiry. “The kind of
research my group does was not usual when I started 25-30
years ago,” said Miller. “The field has really developed over
that time.”
This is a rendition of a one-dimensional, needle-like nanocrystal,
such as the one prepared by Javier Vela in collaboration with Em-
ily Smith and Jacob Petrich. Vela’s team has prepared a family of
highly luminescent perovskite nanocrystals with shape correlated
emission.
Javier Vela
Aaron Sadow
Gordon Miller
“The interesting thing
for me is these materials
provide the opportunity to
access new mechanisms
and new pathways, and if
we can understand those
pathways, we can use these
earth-abundant metals
in interesting processes
that could one day have
an impact on industrial
catalysis.”