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Nature Materials Study: Boosting Heat Transfer With Nanoglue
Interdisciplinary Study From Rensselaer
Polytechnic Institute Demonstrates New Method for Significantly
Increasing Heat Transfer Rate Across Two Different
Materials
A team of interdisciplinary researchers at Rensselaer Polytechnic Institute
has developed a new method for significantly increasing the
heat transfer rate across two different materials. Results of
the team’s study, published in the journal Nature
Materials, could enable new advances in cooling computer
chips and lighting-emitting diode (LED) devices, collecting
solar power, harvesting waste heat, and other applications.
By sandwiching a layer of ultrathin “nanoglue” between
copper and silica, the research team demonstrated a four-fold
increase in thermal conductance at the interface between the
two materials. Less than a nanometer—or one billionth of a
meter—thick, the nanoglue is a layer of molecules that form
strong links with the copper (a metal) and the silica (a
ceramic), which otherwise would not stick together well. This
kind of nanomolecular locking improves adhesion, and also helps
to sync up the vibrations of atoms that make up the two
materials which, in turn, facilitates more efficient transport
of heat particles called phonons. Beyond copper and silica, the
research team has demonstrated their approach works with other
metal-ceramic interfaces.
Heat transfer is a critical aspect of many different
technologies. As computer chips grow smaller and more complex,
manufacturers are constantly in search of new and better means
for removing excess heat from semiconductor devices to boost
reliability and performance. With photovoltaic devices, for
example, better heat transfer leads to more efficient
conversion of sunlight to electrical power. LED makers are also
looking for ways to increase efficiency by reducing the
percentage of input power lost as heat. Ganapati Ramanath,
professor in the Department of Materials Science
and Engineering at Rensselaer, who led the new study, said
the ability to enhance and optimize interfacial thermal
conductance should lead to new innovations in these and other
applications.
“Interfaces between different materials are often heat-flow
bottlenecks due to stifled phonon transport. Inserting a third
material usually only makes things worse because of an
additional interface created,” Ramanath said. “However, our
method of introducing an ultrathin nanolayer of organic molecules that
strongly bond with both the materials at the interface gives
rise to multi-fold increases in interfacial thermal
conductance, contrary to poor heat conduction seen at
inorganic-organic interfaces. This method to tune thermal
conductance by controlling adhesion using an organic nanolayer
works for multiple materials systems, and offers a new means
for atomic- and molecular-level manipulation of multiple
properties at different types of materials interfaces. Also,
it’s cool to be able to do this rather unobtrusively by the
simple method of self-assembly of a single layer of
molecules.”
Results of the new study, titled “Bonding-induced thermal
conductance enhancement at inorganic heterointerfaces using
nanomolecular monolayers,” were published online last week by
Nature Materials, and will appear in an upcoming print
edition of the journal. The study may be viewed online at: http://go.nature.com/3LLeYP
The research team used a combination of experiments and
theory to validate their findings.
“Our study establishes the correlation between interfacial
bond strength and thermal conductance, which serves to underpin
new theoretical descriptions and open up new ways to control
interfacial heat transfer,” said co-author Pawel Keblinski,
professor in the Department of Materials Science and
Engineering at Rensselaer.
“It is truly remarkable that a single molecular layer can
bring about such a large improvement in the thermal properties
of interfaces by forming strong interfacial bonds. This would
be useful for controlling heat transport for many applications
in electronics, lighting, and energy generation,” said
co-author Masashi Yamaguchi,
associate professor in the Department of Physics,
Applied Physics, and Astronomy at Rensselaer.
This study was funded with support from the National Science Foundation
(NSF).
“The overarching goal of Professor Ramanath’s NSF-sponsored
research is to elucidate, using first-principles-based models,
the effects of molecular chemistry, chemical environment,
interface topography, and thermo-mechanical cycling on the
thermal conductance of metal-ceramic interfaces modified with
molecular nanolayers,” said Clark V. Cooper, senior advisor for
science at the NSF Directorate for Mathematical and Physical
Sciences, who formerly held the post of program director for
Materials and Surface Engineering. “Consistent with NSF’s
mission, the focus of his research is to advance fundamental
science, but the potential societal benefits of the research
are enormous.”
“This is a fascinating example of the interplay between the
physical, chemical, and mechanical properties working in unison
at the nanoscale to determine the heat transport
characteristics at dissimilar metal-ceramic interfaces,” said
Anupama B. Kaul, a program director for the Division of
Electrical, Communications, and Cyber Systems at the NSF
Directorate for Engineering. “The fact that the organic
nanomolecular layer is just a monolayer in thickness and yet
has such an important influence on the thermal characteristics
is truly remarkable. Dr. Ramanath’s results should be
particularly valuable in nanoelectronics where heat management
due to shrinking device dimensions continues to be an area of
active research.”
Along with Ramanath, Keblinski, and Yamaguchi, co-authors of
the paper are Rensselaer materials science graduate students
Peter O’Brien, Sergei Shenogin, and Philippe K. Chow;
Rensselaer physics graduate student Jianxiun Liu; and Danielle
Laurencin and P. Hubert Mutin of the Institut Charles Gerhardt
Montpellier and Université Montpellier in France.
For more information on Ramanath and his nanomaterials
research at Rensselaer, visit:
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Published
December 4,
2012 |
Contact: Michael Mullaney
Phone: (518) 276-6161
E-mail: mullam@rpi.edu |
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