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Effective understanding and design of nanocrystals
Researchers at the DOE’s Lawrence Berkeley
National Laboratory, Calif., used highly sophisti-
cated transmission electron microscopes (TEM)
and an advanced high-resolution, fast-detection
camera to capture the physical mechanisms that
control the evolution of facets on the surfaces of
platinum nanocubes formed in liquids. Under-
standing how facets develop on a nanocrystal is
critical to controlling the crystal’s geometric
shape, which in turn is critical to controlling its
chemical and electronic properties.
Working with platinum, Haimei Zheng and her
team initiated the growth of nanocubes in a thin
liquid layer sandwiched between two silicon nitride
membranes. This microfabricated cell can encap-
sulate and maintain the liquid inside the high vac-
uum of a TEM for an extended period of time,
enabling in situ observations of single nanoparticle
growth trajectories.
Fully wearable and flexible devices closer to reality
A new prototype is a first example of how the
partnership between the Cambridge Graphene Cen-
tre and Plastic Logic, both in the UK, will accelerate
commercial graphene development. The prototype
is an active matrix electrophoretic display, similar
to the screens used in e-readers, but it is made of
flexible plastic instead of glass. In contrast to con-
ventional displays, the pixel electronics, or back-
plane, of this display includes a solution-processed
graphene electrode. The new 150 pixel per inch
backplane was made at low temperatures (<100°C)
using Plastic Logic’s organic thin film transistor technology. The graphene electrode was
deposited from solution and subsequently patterned with micron-scale features to com-
plete the backplane, which was then combined with an electrophoretic imaging film to
create an ultra-low power and durable display. , .
Meet graphene’s cousin, germanene
Germanene, which is made up of just a single layer of germaniumatoms, is expected to ex-
hibit impressive electrical and optical properties and could be widely integrated across the elec-
tronics industry in the future. Germanene, first proposed in 2009, has remained elusive until
now. Much like silicene, the proposed method for synthesizing germanene is to deposit indi-
vidual germanium atoms onto a substrate under high temperatures and in an ultra-high vac-
uum. The breakthrough by a European research team was made in parallel
with an independent team from China who reported evidence that ger-
manene has been synthesized onto a platinumsubstrate. The European team
serendipitously discovered that gold could also be used as a substrate, an
event which professor Guy Le Lay, fromAix-Marseille University, France,
described as “like passing through the looking glass.” .
A 16.2 × 16.2 nm STM image of the modulated honeycomb √7×√7 super-
structure. Atomic structures (side and top views) and simulated STM images of
three different models of germanene on the √7×√7 Au(111) surface. Courtesy
of New Journal of Physics /IOP Publishing.
ADVANCED MATERIALS & PROCESSES • NOVEMBER-DECEMBER 2014 14
NANOTECHNOLOGY
briefs
Morgan Advanced Materials,
Windsor, UK, announced a new
joint development agreement with
The University of Manchester,
aimed at scaling up a novel
process for manufacturing
graphene. The partnership will
explore the full potential of
graphene, with a particular interest
in understanding and optimizing
the relationship between the
manufacturing process and
materials science, and was
established to improve the
prospects of bringing this material
to commercial reality.
,
.
Applied Nanotech Holdings Inc.,
Deerfield Beach, Fla., and
NanoHoldings Inc., Rowaton,
Conn., created a new company
called PEN Inc. to focus on
commercialization of advanced
nanotechnology-enabled products.
PEN unites staff and resources in
nanotechnology research and
development with experience in
specialty product commercialization.
,
,
.
Stanford University, Calif.,
materials scientists detailed a key
step in storing energy and
information in nanomaterials by
studying how metallic
nanoparticles composed of
palladium absorb and release
hydrogen atoms. Hydrogen
absorption in ensembles of
metallic nanoparticles has been
previously studied, but this
approach makes it difficult to infer
information about how the
individual nanoparticles behave.
The new work reveals that
behavior by measuring the
hydrogen content in individual
palladium nanoparticles exposed
to increasing pressures of
hydrogen gas. .
Researchers found that differences in
ligand mobility during crystallization
cause the low index facets—{100},
{110} and {111}—to stop growing at
different times, resulting in the crystal’s
final cubic shape. Courtesy of Haimei
Zheng group, Berkeley Lab.
A flexible display incorporating
graphene in its pixels’ electronics
was successfully demonstrated—the
first time graphene has been used in
a transistor-based flexible device.