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Self-correcting crystal holds promise for advanced electronics
Researchers from the National Institute
of Standards and Technology (NIST),
Gaithersburg, Md., joined with an interna-
tional team to engineer and measure a prom-
ising new class of nanostructured materials
for microwave and advanced communication
devices. Based on NIST’s measurements, the
novel materials—a family of multilayered
crystalline sandwiches—could enable an in-
novative class of compact, high performance,
high efficiency components for devices such
as mobile phones.
“These materials are an excellent example
of what the Materials Genome Initiative refers
to as materials-by-design,” explains NIST
physicist James Booth. “Materials science
keeps getting better at engineering complex
structures at an atomic scale to create materi-
als with previously unheard-of properties.”
According to NIST materials scientist Nathan Orloff, “People have created tunable mi-
crowave dielectrics for decades, but they use up way too much power.” The new materials
work well up to 100 GHz, setting the stage for the next generation of advanced communi-
cations devices.
Modern cellphone dielectrics use materials that suffer from defects within their crys-
tal structure, which interferes with the dielectric properties and leads to power loss. One
major feature of the new materials, says Orloff, is that they self-correct, reducing the effect
of defects in the part of the crystal where it counts.
The new material has layers of strontium oxide, believed to be responsible for the self-
correcting feature, separating a variable number of layers of strontium titanate. Layers are
grown as a thin crystalline film on top of a substrate material with a mismatched crystal
spacing that produces strain within the strontium titanate structure that makes it a less
stable dielectric, but one that can be tuned.
The new sandwich material performs so well as a tunable dielectric, over such a broad
range of frequencies that the NIST team had to develop a new measurement technique to
measure its electronic characteristics. “We were able to characterize the performance of
these materials as a function of frequency running from 10 hertz all the way up to 125 gi-
gahertz,” says Orloff. “This material has a much lower loss and a much higher tunability for
a given applied field than any material we have seen.”
Research aims to model
behavior of ultra-cold atoms
Ana Maria Rey, a National Science Foundation
(NSF)-funded scientist and research assistant professor
at the University of Colorado Boulder’s Department of
Physics is a recent recipient of one of the prestigious
MacArthur fellowships, a $625,000 award popularly
known as a “genius” grant.
Since 2008, Rey also received about $500,000 in NSF
funding for work that includes modeling the behavior of
ultra-cold atoms and polar molecules. She and her col-
leagues create artificial materials by trapping atoms
with light. This research could lead to new materials for
more effective superconductors, as well as new mag-
briefs
The state of Texas recently
awarded $1 million to the new Oil
& Gas Materials Technology
Center, part of Element Houston.
The center, located on a 5.3-acre
campus adjacent to the Houston
energy corridor, will use the funds
to research applications of high
performance polymers for energy
applications. The $5 million
laboratory, Element’s largest single
site investment, also offers
advanced fracture mechanics and
corrosion testing. .
The University of Manchester,
UK, received a Queen’s
Anniversary Prize for its efforts to
support strategic development in
advanced materials and
manufacturing. The award
recognizes the university’s
expertise in developing new
techniques for 3D imaging of
material structures and defects,
and interpreting the state of stress,
microstructure, and damage in
engineering materials and
components.
.
Researchers at the University of
Manchester recently received a
Queen’s Anniversary Prize.
What is known to be the biggest
and most advanced wind energy
testing facility in the U.S. is now
open in North Charleston, S.C.,
supported by a $47 million
Department of Energy grant and
$60 million in outside funding. Led
by Clemson University’s
Restoration Institute, the facility
will test and validate new turbines.
Machinery that converts both
onshore and offshore wind to
electricity will also be tested.
Engineers will be able to simulate
20 years’ worth of wear and tear
on drivetrains in just a few months.
.
ADVANCED MATERIALS & PROCESSES • JANUARY 2014 8
TESTING CHARACTERIZATION
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Electron microscope image of a cross
section of the newly characterized tunable
microwave dielectric shows thick layers of
strontium titanate “bricks” separated by thin
“mortar lines” of strontium oxide that help
promote largely defect-free brick growth.
Courtesy of David Mueller.
Ana Maria Rey of the University of
Colorado Boulder received a
MacArthur Fellowship in 2013 to
study the behavior of ultra-cold
atoms. Courtesy of Casey Cass.