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A D V A N C E D
M A T E R I A L S
&
P R O C E S S E S |
M A Y / J U N E
2 0 1 7
1 5
A MODEL COMPOUND
Researchers at Rice University,
Houston, built computer simulations
of a compound composed of 2D mag-
nesium oxide in bilayer graphene and
determined that the material offers a
range of unique optoelectronic prop-
erties. Unlike graphene on its own, the
hybrid has a band gap—the charac-
teristic that makes a material a semi-
conductor—and its band gap could
be tunable depending on the compo-
nents. The compound’s enhanced op-
tical properties are also tunable—and
desirable. While a flake of magnesium
oxide alone absorbs only one kind of
light emission, sandwiching it between
layers of graphene allows it to absorb
a wide spectrum of light. This could
be an important mechanism for deli-
cate molecular sensing. The compound
could also find application in catalysis
and bio-imaging.
To choose a foundation for
their model, the scientists looked
to previous exper-
iments where var-
ious molecules were
encapsulated using
van der Waals forces
to draw components
together. The Rice
study is reportedly the
first to take a theoreti-
cal approach to defin-
ing the electronic and
optical properties of
one of those “made”
samples.
“We knew if there was an exper-
iment already performed, we would
have a great reference point that would
make it easier to verify our compu-
tations,” explains materials scientist
Rouzbeh Shahsavari. He went on to
say that his group’s theory should be
applicable to other 2D materials like
hexagonal boron-nitride and molecular
fillings. Ultimately, the work could help
researchers design a range of custom-
izable hybrids of 2D and 3D structures
with encapsulated molecules. rice.edu.
UNRAVELING THE MYSTERY OF
A BUG’S BODY ARMOR
Scientists at the University of Ne-
braska-Lincoln discovered a method
to analyze the fibrous nanostructure
of a beetle’s shell, gaining insights that
could lead to development of lighter
and stronger engineered materials.
Composed of chitin fibers just 20 nm in
diameter packed and piled into spiraled
layers, the exoskeleton is both hardy
and lightweight, protecting the beetle’s
delicate wings without weighing it
down in flight. Analyzing the armor’s
architecture has been difficult in the
past due to the fibers’ small diameter
and helical twisting, known as a Bouli-
gand-type structure. To gain insight
into this architecture, the researchers
developed a method of slicing down
the spiral to reveal a surface of fiber
cross-sections at different orienta-
tions. Next they investigated the fibers
with an atomic force microscope. The
process revealed both the nanoscale
structure of the exoskeleton and the
material properties of the nanofibers.
They made their discoveries by analyz-
ing the common figeater beetle, Cotinis
mutabilis, a metallic green native of the
western United States. The technique
could be applied to other hard-shelled
creatures as well as artificial materials
with fibrous structures and could lead
to improvements in body armor as well
as automotive and aerospace compo-
nent
NANOTECHNOLOGY
BRIEF
Rutgers University, New Brunswick, N.J., licensed a technology that enables mass production of graphene at a
reduced cost to Everpower International Holdings Co. Ltd., New York. The method uses microwaves to produce
high-quality graphene from graphene oxide.
Nanoclusters of magnesium oxide sandwiched between
layers of graphene produce a compound with unique elec-
tronic and optical properties, according to researchers who
made computer simulations of the material.
Courtesy of Lei Tao.
Common figeater beetle. Courtesy of
bugguide.net.