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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 | A P R I L 2 0 1 5
1 4 ENERGY TRENDS
material’s atomic lattice—would speed
the transport of oxygen ions through
the material, potentially leading to
much faster diffusion than necessary in
high-performance solid oxide fuel cells,
water-splitting, or oxygen-separation
membranes. But the new atomic-
level simulation of oxide ion transport
reveals that while these dislocations
do greatly accelerate atom transport
in metals, they can have the opposite
effect in this metal-oxide material, and
possibly in others.
Instead of easing ion mobility, it
turns out that dislocations in cerium
dioxide cause a kind of “traffic jam”
for the flowing ions, slowing them to
a crawl, says graduate student Lixin
Simulations show the effects of dislocations in ceriumdioxide on the redistribution
of differently sized dopant atoms, replacing a cerium atom in the crystal lattice.
Results reveal different amounts of segregation around the dislocation caused by
the differently sized elements. The sizes of the other atoms are compared to a
cesium atom (left, in black). The white dashed line shows the plane of the disloca-
tion caused by strain. Courtesy of the researchers.
SURPRISING PROPERTY
FOUND IN OXIDES
Dislocations in oxides such as
cerium dioxide, a solid electrolyte for
fuel cells, have a property that is the
opposite of what researchers expect-
ed, according to new analysis at Mas-
sachusetts Institute of Technology,
Cambridge. Researchers thought that
a certain kind of strain—specifically,
strain caused by dislocations in the
Sun. The surprising result suggests
that a different approach is needed to
try to speed up the movement of these
ions. For more information: Lixin Sun,
617.253.1749,
POLYMER BLEND ENABLES
MORE EFFICIENT SOLAR
POWER
A University of Cincinnati, Ohio, re-
search partnership is reporting advanc-
es on how to one day make solar cells
stronger, lighter, more flexible, and less
expensive when compared with the cur-
rent silicon or germanium technology
on the market.
Yan Jin, a UC doctoral student in
the materials science and engineering
program, describes how a blend of con-
jugated polymers resulted in structural
and electronic changes that increased
efficiency three-fold, by incorporating
pristine graphene into the active layer of
the carbon-based materials. The tech-
nique results in better charge transport,
short-circuit current, and a more than
200% improvement in device efficien-
cy. “We investigated the morphological
changes underlying this effect by using
small-angle neutron scattering (SANS)
studies of the deuterated-P3HT/F8BT
with and without graphene,” says Jin.
The partnership with Oak Ridge
National Laboratory and the DOE is
exploring how to improve the perfor-
mance of carbon-based synthetic poly-
mers, with the ultimate goal of mak-
ing them commercially competitive. The Energy Department announc-
es up to $35 million in available
funding to advance fuel cell and
hydrogen technologies, and enable
early adoption of fuel cell appli-
cations, such as light duty fuel
cell electric vehicles. This funding
opportunity aims to boost U.S.
innovation in these technologies
by supporting both research and
development efforts and initial
deployments. .
BRIEFS
Helsinki Region Transport and VTT Technical Research Centre of
Finland Ltd. will launch an extensive joint pilot program to introduce
highly efficient lightweight electric buses with technology to charge their
batteries during operation. The buses use quickly rechargeable batteries
and feature aluminum frames. Other benefits include zero emissions and
quiet operation, say researchers. .