David Kirkpatrick

November 4, 2010

Transparent solar panels?

A very real possibility. This sounds like very promising technology.

The release:

Transparent Conductive Material Could Lead to Power-Generating Windows

Combines elements for light harvesting and electric charge transport over large, transparent areas

November 3, 2010

conjugated polymer honeycombClick on the image to download a high-resolution version.Top: Scanning electron microscopy image and zoom of conjugated polymer (PPV) honeycomb. Bottom (left-to-right): Confocal fluorescence lifetime images of conjugated honeycomb, of polymer/fullerene honeycomb double layer and of polymer/fullerene honeycomb blend. Efficient charge transfer within the whole framework is observed in the case of polymer/fullerene honeycomb blend as a dramatic reduction in the fluorescence lifetime.

UPTON, NY — Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Los Alamos National Laboratory have fabricated transparent thin films capable of absorbing light and generating electric charge over a relatively large area. The material, described in the journal Chemistry of Materials, could be used to develop transparent solar panels or even windows that absorb solar energy to generate electricity.

The material consists of a semiconducting polymer doped with carbon-rich fullerenes. Under carefully controlled conditions, the material self-assembles to form a reproducible pattern of micron-size hexagon-shaped cells over a relatively large area (up to several millimeters).

“Though such honeycomb-patterned thin films have previously been made using conventional polymers like polystyrene, this is the first report of such a material that blends semiconductors and fullerenes to absorb light and efficiently generate charge and charge separation,” said lead scientist Mircea Cotlet, a physical chemist at Brookhaven’s Center for Functional Nanomaterials (CFN).

Furthermore, the material remains largely transparent because the polymer chains pack densely only at the edges of the hexagons, while remaining loosely packed and spread very thin across the centers. “The densely packed edges strongly absorb light and may also facilitate conducting electricity,” Cotlet explained, “while the centers do not absorb much light and are relatively transparent.”

Mircea CotletClick on the image to download a high-resolution version.Mircea Cotlet, Ranjith Krishna Pai, and Zhihua Xu (seated at the microscope).

“Combining these traits and achieving large-scale patterning could enable a wide range of practical applications, such as energy-generating solar windows, transparent solar panels, and new kinds of optical displays,” said co-author Zhihua Xu, a materials scientist at the CFN.

“Imagine a house with windows made of this kind of material, which, combined with a solar roof, would cut its electricity costs significantly. This is pretty exciting,” Cotlet said.

The scientists fabricated the honeycomb thin films by creating a flow of micrometer-size water droplets across a thin layer of the polymer/fullerene blend solution. These water droplets self-assembled into large arrays within the polymer solution. As the solvent completely evaporates, the polymer forms a hexagonal honeycomb pattern over a large area.

“This is a cost-effective method, with potential to be scaled up from the laboratory to industrial-scale production,” Xu said.

The scientists verified the uniformity of the honeycomb structure with various scanning probe and electron microscopy techniques, and tested the optical properties and charge generation at various parts of the honeycomb structure (edges, centers, and nodes where individual cells connect) using time-resolved confocal fluorescence microscopy.

The scientists also found that the degree of polymer packing was determined by the rate of solvent evaporation, which in turn determines the rate of charge transport through the material.

“The slower the solvent evaporates, the more tightly packed the polymer, and the better the charge transport,” Cotlet said.

“Our work provides a deeper understanding of the optical properties of the honeycomb structure. The next step will be to use these honeycomb thin films to fabricate transparent and flexible organic solar cells and other devices,” he said.

The research was supported at Los Alamos by the DOE Office of Science. The work was also carried out in part at the CFN and the Center for Integrated Nanotechnologies Gateway to Los Alamos facility. The Brookhaven team included Mircea Cotlet, Zhihua Xu, and Ranjith Krishna Pai. Collaborators from Los Alamos include Hsing-Lin Wang and Hsinhan Tsai, who are both users of the CFN facilities at Brookhaven, Andrew Dattelbaum from the Center for Integrated Nanotechnologies Gateway to Los Alamos facility, and project leader Andrew Shreve of the Materials Physics and Applications Division.

The Center for Functional Nanomaterials at Brookhaven National Laboratory and the Center for Integrated Nanotechnologies Gateway to Los Alamos facility are two of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories.

 

March 26, 2010

Nanotech and safer nuclear power

A very interesting release:

Safer nuclear reactors could result from Los Alamos research

‘Loading-unloading’ effect of grain boundaries key to repair of irradiated metal

Self-repairing materials within nuclear reactors may one day become a reality as a result of research by Los Alamos National Laboratory scientists.

In a paper appearing today in the journal Science, Los Alamos researchers report a surprising mechanism that allows nanocrystalline materials to heal themselves after suffering radiation-induced damage. Nanocrystalline materials are those created from nanosized particles, in this case copper particles. A single nanosized particle—called a grain—is the size of a virus or even smaller. Nanocrystalline materials consist of a mixture of grains and the interface between those grains, called grain boundaries.

When designing nuclear reactors or the materials that go into them, one of the key challenges is finding materials that can withstand an outrageously extreme environment. In addition to constant bombardment by radiation, reactor materials may be subjected to extremes in temperature, physical stress, and corrosive conditions. Exposure to high radiation alone produces significant damage at the nanoscale.

Radiation can cause individual atoms or groups of atoms to be jarred out of place. Each vagrant atom becomes known as an interstitial. The empty space left behind by the displaced atom is known as a vacancy. Consequently, every interstitial created also creates one vacancy. As these defects—the interstitials and vacancies—build up over time in a material, effects such as swelling, hardening or embrittlement can manifest in the material and lead to catastrophic failure.

Therefore, designing materials that can withstand radiation-induced damage is very important for improving the reliability, safety and lifespan of nuclear energy systems.

Because nanocrystalline materials contain a large fraction of grain boundaries—which are thought to act as sinks that absorb and remove defects—scientists have expected that these materials should be more radiation tolerant than their larger-grain counterparts. Nevertheless, the ability to predict the performance of nanocrystalline materials in extreme environments has been severely lacking because specific details of what occurs within solids are very complex and difficult to visualize.

Recent computer simulations by the Los Alamos researchers help explain some of those details.

In the Science paper, the researchers describe the never-before-observed phenomenon of a “loading-unloading” effect at grain boundaries in nanocrystalline materials. This loading-unloading effect allows for effective self-healing of radiation-induced defects. Using three different computer simulation methods, the researchers looked at the interaction between defects and grain boundaries on time scales ranging from picoseconds to microseconds (one-trillionth of a second to one-millionth of a second).

On the shorter timescales, radiation-damaged materials underwent a “loading” process at the grain boundaries, in which interstitial atoms became trapped—or loaded—into the grain boundary. Under these conditions, the subsequent number of accumulated vacancies in the bulk material occurred in amounts much greater than would have occurred in bulk materials in which a boundary didn’t exist. After trapping interstitials, the grain boundary later “unloaded” interstitials back into vacancies near the grain boundary. In so doing, the process annihilates both types of defects—healing the material.

This unloading process was totally unexpected because grain boundaries traditionally have been regarded as places that accumulate interstitials, but not as places that release them. Although researchers found that some energy is required for this newly-discovered recombination method to operate, the amount of energy was much lower than the energies required to operate conventional mechanisms—providing an explanation and mechanism for enhanced self-healing of radiation-induced damage.

Modeling of the “loading-unloading” role of grain boundaries helps explain previously observed counterintuitive behavior of irradiated nanocrystalline materials compared to their larger-grained counterparts. The insight provided by this work provides new avenues for further examination of the role of grain boundaries and engineered material interfaces in self-healing of radiation-induced defects. Such efforts could eventually assist or accelerate the design of highly radiation-tolerant materials for the next generation of nuclear energy applications.

###

The Los Alamos National Laboratory research team includes: Xian-Ming Bai, Richard G. Hoagland and Blas P. Uberuaga of the Materials Science and Technology Division; Arthur F. Voter, of the Theoretical Division; and Michael Nastasi of the Materials Physics and Applications Division.

The work was primarily sponsored by the Los Alamos Laboratory-Directed Research and Development (LDRD) program, which, at the discretion of the Laboratory Director, invests a small percentage of the Laboratory’s budget in high-risk, potentially high-payoff projects to help position the Laboratory to anticipate and prepare for emerging national security challenges. The research also received specific funding through the Center for Materials under Irradiation and Mechanical Extremes, an Energy Frontier Research Center funded by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences.

About Los Alamos National Laboratory (www.lanl.gov)

Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and URS for the Department of Energy’s National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

November 16, 2009

Meet the latest supercomputing champ — Jaguar Cray

Via KurzweilAI.net — Over one petaflop per second!

Cray’s Jaquar now world’s fastest supercomputer
KurzweilAI.net, Nov. 15, 2009

The Jaguar Cray supercomputer at Oak Ridge National Laboratory has become the world’s most powerful supercomputer, at 1.75 petaflops per second, edging out the IBM Roadrunner system at the U.S. Department of Energy‘s Los Alamos National Laboratory in New Mexico, which has slowed slightly to 1.04 petaflops per second.

The newest version of the TOP500 list, which is issued twice yearly, will be formally presented on Tuesday, Nov. 17, at the SC09 Conference, to be held at the Oregon Convention Center in Portland.

Source: Top 500 news release

March 30, 2009

A “Map of Science” from Los Alamos

Filed under: Media, Science, Technology — Tags: , , , — David Kirkpatrick @ 3:10 am

Here’s the release from earlier this month — you’ll have to hit the link for the map.

From the link:

Los Alamos Researchers Create ‘Map of Science’

LOS ALAMOS, N.M., March 11, 2009 — Data provides high-resolution picture of scientists’ information retrieval habits

Los Alamos National Laboratory scientists have produced the world’s first Map of Science—a high-resolution graphic depiction of the virtual trails scientists leave behind when they retrieve information from online services. The research, led by Johan Bollen, appears this week in PLoS ONE (the Public Library of Science).

“This research will be a crucial component of future efforts to study and predict scientific innovation, as well novel methods to determine the true impact of articles and journals,” Bollen said.

While science is of tremendous societal importance, it is difficult to probe the often hidden world of scientific creativity. Most studies of scientific activity rely on citation data, which takes a while to become available because both the cited publication and the publication of a particular citation can take years to appear. In other words, citation data observes science as it existed years in the past, not the present.

Bollen and colleagues from LANL and the Santa Fe Institute collected usage-log data gathered from a variety of publishers, aggregators, and universities spanning a period from 2006 to 2008. Their collection totaled nearly 1 billion online information requests. Because scientists typically read articles online well before they can be cited in subsequent publications, usage data reveal scientific activity nearly in real-time. Moreover, because log data reflect the interactions of all users—such as authors, science practitioners, and the informed public—they do not merely reflect the activities of scholarly authors.

Whenever a scientist accesses a paper online from a publisher, aggregator, university, or similar publishing service, the action is recorded by the servers of these Web portals. The resulting usage data contains a detailed record of the sequences of articles that scientists download as they explore their present interests. After counting the number of times that scientists, across hundreds of millions of requests, download one article after another, the research team calculated the probability that an article or journal accessed by a scientist would be followed by a subsequent article or journal as part of the scientists’ online behavior. Based on such behavior, the researchers created a map that graphically portrays a network of connected articles and journals.

Bollen and colleagues were surprised by the map’s scope and detail. Whereas maps based on citations favor the natural sciences, the team’s maps of science showed a prominent and central position for the humanities and social sciences, which, in many places, acted like interdisciplinary bridges connecting various other scientific domains. Sections of the maps were shaped by the activities of practitioners who read the scientific literature but do not frequently publish in its journals.

The maps furthermore revealed unexpected relations between scientific domains that point to emerging relationships that are capturing the collective interest of the scientific community—for instance a connection between ecology and architecture.

“We were surprised by the fine-grained structure of scientific activity that emerges from our maps,” said Bollen.

According to Bollen, future work will focus on issues involved in the sustainable management of large-scale usage data, as well the production of models that explain the online behavior of scientists and how it relates to the emergence of scientific innovation. This information will help funding agencies, policy makers, and the public to better understand how best to tap the ebb and flow of scientific inquiry and discovery.

The research team includes Bollen, Herbert Van de Sompel, Ryan Chute, and Lyudmila Balakireva of LANL’s Digital Library Research and Prototyping Team and Aric Hagberg, Luis Bettencourt and Marko A Rodriguez of LANL’s Mathematical Modeling and Analysis Group, and LANL’s Center for Nonlinear Studies. Bettencourt also is part of the Santa Fe Institute.

Bollen and colleagues received funding from the Andrew W. Mellon foundation to examine the potential of large-scale usage data. The study is part of the MESUR (Metrics from Scholarly Usage of Resources) project of which Bollen is the principal investigator. The MESUR usage database is now considered the largest of its kind.

Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and the Washington Division of URS for the Department of Energy’s National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

November 21, 2008

Los Alamos announces superconductivity news

The release:

Los Alamos Scientists See New Mechanism for Superconductivity

When materials are tuned to a critical point at absolute zero temperature, quantum effects dictate universal behavior in material properties. The presence of a singular point is revealed through its unusual electronic properties outside a new form of matter that hides the singularity.

Quantum Blackhole (in condensed matter): When materials are tuned to a critical point at absolute zero temperature, quantum effects dictate universal behavior in material properties. The presence of a singular point is revealed through its unusual electronic properties outside a new form of matter that hides the singularity.   enlarge image

Quantum

Quantum “Alchemy”: Formation of superconductivity in the vicinity of a singular critical point defies the conventional belief that turbulent electronic fluctuations are not beneficial to form the macroscopic quantum state. The unheralded source of superconductivity holds promise for the design of a room temperature superconductor.   enlarge image

LOS ALAMOS, N.M., November 24, 2008 — Laboratory researchers have posited an explanation for superconductivity that may open the door to the discovery of new, unconventional forms of superconductivity.

In a November 20 Nature letter, research led by Tuson Park and Joe D. Thompson describes a new explanation for superconductivity in non-traditional materials—one that describes a potentially new state of matter in which the superconducting material behaves simultaneously as a nonmagnetic material and a magnetic material.

Superconducting materials carry a current without resistance, usually when cooled to temperatures nearing the liquid point of helium (nearly 452 degrees below zero Fahrenheit). Superconductors are extremely important materials because they hold promise for carrying electricity from one place to another without current loss or providing indefinite electric storage capacity. However, the cost of cooling materials to such extremely low temperatures currently limits the practicality of superconductors. If superconductors could be designed to operate at temperatures closer to room temperature, the results would be revolutionary.

Traditional theories of superconductivity hold that electrons within certain nonmagnetic materials can pair up when jostled together by atomic vibrations known as phonons. In other words, phonons provide the “glue” that makes superconductivity possible.

Park and his colleagues now describe a different type of “glue” giving rise to superconducting behavior.

Park and his colleagues cooled a compound of Cerium, Rhodium and Indium to just above absolute zero, nearly minus 459 degrees Fahrenheit. At this temperature, the material exhibits superconducting behavior. However, they also subjected the crystal to pressure changes and a magnetic field to perturb the alignment of electrons within the material.

“We introduced very high quantum fluctuations in the material,” Park said. “In other words, we made the electrons like a traffic jam, where it would be very difficult for them to move.”

This electronic traffic jam would discourage electron pairing by phonons; nevertheless, the material continued to exhibit superconducting behavior.

Based on the material’s behavior under different pressures and temperatures, researchers believe that the material reaches a quantum critical point near absolute zero. At this quantum critical point, the material retained properties of a metal with highly ordered electrons and highly disordered ones—a previously undescribed state of matter.

Park and his colleagues believe that this quantum critical point provides a mechanism to pair electrons into a quantum state that gives rise to superconducting behavior. In other words, the research helps explain a mechanism for superconductivity without phonons.

“This quantum critical point could be analogous to a black hole,” said Park. “We can see what is happening at or near the event horizon—superconductivity—but we cannot yet see inside to understand why.”

A new mechanism for the electron-pairing glue that gives rise to superconductivity could allow researchers to design new materials that exhibit superconducting materials at higher temperatures, perhaps even opening the door to the “Holy Grail” of superconducting materials—one that works at room temperature.

Park’s colleagues include: Vladimir Sidorov, Filip Ronning, Jian-Xin Zhu, Yoshifumi Tokiwa, Hanoh Lee, Eric Bauer, Roman Movshovich, John Sarrao and Joe D. Thompson.

The research was supported by the U.S. Department of Energy’s Office of Science and Office of Basic Energy Science and funded in part by Los Alamos National Laboratory.

 

Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and Washington Group International for the Department of Energy’s National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

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