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  • richardmitnick 6:44 pm on December 6, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory, Helium   

    From ANL: “Underground helium travels to the Earth’s surface via aquifers, new study says” 

    News from Argonne National Laboratory

    December 5, 2014
    Louise Lerner

    Before it can put the party in party balloons, helium is carried from deep within the Earth’s crust to the surface via aquifers, according to new research published this week in Nature Geosciences.

    Aquifers, underground water formations that provide water to millions of people around the world, contain water that has filtered there over hundreds of millennia. Using an atom trap built at the U.S. Department of Energy’s Argonne National Laboratory to date the water in a deep South American aquifer, scientists tracked the rate at which helium pooled in the aquifers. The results suggest that helium is trickling into the aquifer from deeper underground, where it is carried to the surface with the flow of water.

    The only place where helium is made on Earth is underground, where deep veins of uranium and thorium give off atoms of helium as they decay. This helium eventually makes its way to the surface, where it escapes into the atmosphere and ultimately into outer space.

    Geoscientists did not know, however, exactly how this helium gets to the surface. It can filter through rock, but extremely slowly, and the amount of helium in the atmosphere doesn’t match our estimates of how long that would take.

    Some scientists have suggested that helium is released from deeper underground during violent tectonic events like earthquakes or even from underwater volcanoes; but others thought groundwater might be a more likely route.

    Scientists knew the rate at which helium is naturally produced in the aquifer. They just needed to know how old the water was to calculate how much helium would be naturally created during that time span. If the groundwater carried more helium than the aquifers produced themselves, the source for the extra helium would be further beneath the surface.

    Luckily, a group of Argonne researchers led by physicist Zheng-Tian Lu have pioneered a dating technique that uses a very rare isotope called krypton-81. Water picks up this isotope while above ground, but not while below ground; if you know how many atoms of krypton-81 remain in a sample of water, you can tell how long it’s been in the aquifer. And krypton-81 can date much further back than carbon dating—up to a million years or more.

    The atom trap uses lasers that vibrate at the exact same frequency as krypton-81 atoms to count individual atoms. (The team has already used it to track how fast aquifers refill and to date ice in glaciers, among other uses).

    Hydrologists from the International Atomic Energy Agency and their collaborators collected samples of water from various spots around the Guarani aquifer in South America, a massive reservoir that stretches beneath Argentina, Brazil, Paraguay and Uruguay, and extracted all the dissolved gases. Then the krypton was separated out, and finally the samples came to Argonne to have their krypton-81 atoms counted.

    m
    International Atomic Energy Agency hydrologist Luis Araguas-Araguas records data as a machine extracts gases from water samples taken from the Guarani aquifer in South America. The green LED on the front panel indicates the temperature of the water (in this case, 40.9°C, or 106°F). “Generally, the deeper the groundwater, the hotter it is,” said Argonne scientist Wei Jiang, who coauthored a study to track helium as it moves from underground to the surface. Photo by Wei Jiang, Argonne National Laboratory.

    a
    The Guarani aquifer underlays large parts of South America; it supplies water to more than 15 million people. Scientists found helium pools in this aquifer and is released to the atmosphere when the water reaches the surface. Image by Marko Perendija

    The researchers found much more helium than should have been produced in the aquifer itself during the time the water spent there, which indicates that the helium has been filtering up from below and pooling in the aquifer.

    “The difference in helium was a factor of 10—quite significant,” said Argonne physicist Wei Jiang, who coauthored the paper. “This gives us the first solid data for the groundwater scenario.”

    According to the paper’s rough estimate, about half of the helium produced in the crust makes its way to the surface via aquifer.

    “So the helium in your party balloon has very likely been carried around in groundwater,” Lu said.

    Scientists are interested in the global helium cycle because it and other gases are clues to the unseen and mostly mysterious goings-on underneath the Earth’s crust.

    The study’s findings are also helpful to understand aquifers, which provide drinking water and irrigation to millions of people around the world, including half the population of the United States.

    “The International Atomic Energy Agency works with its international partners to improve our understanding of ground water systems so that we can better protect and manage this vital freshwater resource,” said Pradeep Aggarwal, who led the study.

    The work was supported by the Department of Energy’s Office of Science; the development of the krypton-81 dating instrument was supported in part by the National Science Foundation.

    The paper, Continental degassing of helium-4 by surficial discharge of deep groundwater, appears in the Dec. 1 online edition of Nature Geosciences. The lead author was Pradeep Aggarwal of the International Atomic Energy Agency, as well as IAEA scientists Takuya Matsumoto and Luis J. Araguas-Araguas. Other authors included Argonne physicist Peter Mueller, Reika Yokochi of the University of Chicago, Neil Sturchio of the University of Illinois-Chicago, Hung Chang and Didier Gastmans of the Universidade Estadual Paulista, Roland Purtschert of the University of Bern, and Thomas Torgersen of the National Science Foundation.

    See the full article here.

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    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus

     
  • richardmitnick 3:49 pm on October 17, 2014 Permalink | Reply
    Tags: Argonne National Laboratory, , ,   

    From ANL: “Protons hog the momentum in neutron-rich nuclei” 

    News from Argonne National Laboratory

    October 17, 2014
    Kandice Carter, Jefferson Lab Public Affairs, 757-269-7263, kcarter@jlab.org
    or Jared Sagoff, Argonne National Laboratory communications office, 630-252-5549, media@anl.gov.

    Like dancers swirling on the dance floor with bystanders looking on, protons and neutrons that have briefly paired up in the nucleus have higher-average momentum, leaving less for non-paired nucleons. Using data from nuclear physics experiments carried out at the Department of Energy’s Thomas Jefferson National Accelerator Facility, researchers have now shown for the first time that this phenomenon exists in nuclei heavier than carbon, including aluminum, iron and lead.

    nucleons
    Research has shown that protons and neutrons that have briefly paired up in the nucleus have higher-average momentum, which allows a greater fraction of the protons than neutrons to have high momentum in relatively neutron-rich nuclei, such as carbon, aluminum, iron and lead. This result is contrary to long-accepted theories large nuclei and has implications for ultra-cold atomic gas systems and neutron stars.

    The phenomenon also surprisingly allows a greater fraction of the protons than neutrons to have high momentum in these relatively neutron-rich nuclei, which is contrary to long-accepted theories of the nucleus and has implications for ultra-cold atomic gas systems and neutron stars. The results were published online by the journal Science, on the Science Express website.

    The research builds on earlier work featured in Science that found that protons and neutrons in light nuclei pair up briefly in the nucleus, a phenomenon called a short-range correlation. Nucleons prefer pairing up with nucleons of a different type (proton preferred neutrons to other protons) by 20 to 1, and nucleons involved in a short-range correlation carry higher momentum than unpaired ones.

    Using data from an experiment conducted in 2004, the researchers were able to identify high-momentum nucleons involved in short-range correlations in heavier nuclei. In that experiment, led by Argonne physicist Kawtar Hafidi, the Jefferson Lab Continuous Electron Beam Accelerator Facility produced a 5.01 GeV beam of electrons to probe the nuclei of carbon, aluminum, iron and lead. The outgoing electrons and high-momentum protons were measured.

    “We found this dominance of proton-neutron pairs in the nuclei we studied. What’s striking is this pair-dominance all the way to lead,” says Doug Higinbotham, a staff scientist at Jefferson Lab and a lead coauthor on the paper.

    Then the researchers compared the momenta of protons versus neutrons in these nuclei. According to the Pauli exclusion principle, certain like particles can’t have the same momentum state. So, if you have a bunch of neutrons together, some will have low momentum, and others will have high momentum; the more neutrons you have, the more high-momentum neutrons you would see, as they fill up higher and higher momentum states.

    But according to Higinbotham, that expected picture is not what the researchers found when they measured high-momentum protons in neutron-rich nuclei.

    “What this paper is saying is the reverse, that the protons actually have the higher-average momentum. And it’s because they’ve all paired up with neutrons,” Higinbotham says. “It’s like a dance with too many girls (neutrons) and only a few boys (protons). Those boys are dancing their little hearts out, because there aren’t very many of them. So the average proton momentum is going to be higher than the average neutron momentum, because it’s mostly the neutrons that are sitting there, doing nothing, with nothing to pair up with, except themselves.”

    Higinbotham notes that the neutrons may also pair up briefly with other neutrons in short-range correlations and protons with other protons. However, these like-particle brief pairings occur once for roughly every 20 unlike-particle brief pairings.

    Now, the researchers hope to extend these new findings to other, similar systems, such as the quarks in nucleons and atoms in cold gases. According to Or Hen, a graduate student at Tel Aviv University in Israel and the paper’s lead author, he and his colleagues are already reaching out to other researchers.

    “We expect that this will also happen in ultra-cold atomic gas systems. And we’re having meetings with those researchers. If they find the same phenomenon, then we can use the flexibility of their experimental systems to go to extreme cases of very hard-to-study nuclear systems, such as the large imbalances of protons and neutrons that you can find in neutron stars,” Or said.

    To further that goal, Misak Sargsian, a lead coauthor and professor at Florida International University, said he’s extending this work into his own theoretical calculations of neutron stars.

    “Think of a neutron star like it’s a huge nucleus, where you have ten times more neutrons than protons. The effect should be very, very profound for neutron stars. So this opens up a new direction for research,” Sargsian said.

    According to Lawrence Weinstein, a lead coauthor and eminent scholar and professor at Old Dominion University in Norfolk, Va., the scientists would also like to continue their studies of the pairs.

    “We’d like to measure a lot more aspects of how protons and neutrons pair up in nuclei. So we know not just protons prefer neutrons, but how are the pairs behaving, in detail,” he said.

    This new result was made possible by an initiative funded by a grant from the U.S. Department of Energy and led by Weinstein and Sargsian, as well as Mark Strikman, a distinguished professor at Penn State, and Sebastian Kuhn, a professor and eminent scholar at Old Dominion University. The data-mining initiative consisted of re-analyzing experimental data from completed experiments in an attempt to glean new information that previously had not been considered or was missed. A collaboration of more than 140 researchers from more than 40 institutions and nine countries contributed to the result. Researchers at two U.S. Department of Energy national labs, Jefferson Lab and Argonne National Lab, participated in the research.

    Argonne physicist Kawtar Hafidi led the experiment that first collected the data back in 2003. “That data was so unique that we’ve been able to extract all kinds of information on several different areas of nuclear physics since then,” she said. She chairs the group, the CEBAF Large Acceptance Spectrometer collaboration nuclear physics working group, that oversees the review and release of scientific results from the data taken by that experiment.

    “This is excellent work that helps validate our theoretical picture of nuclear structure,” said Robert Wiringa, an Argonne physicist whose theoretical work is cited in the paper.

    The paper was published online by the journal Science, at the Science Express web site, on Thursday, 16 October, 2014. See http://www.sciencexpress.org, and also http://www.aaas.org. Science and Science Express are published by the AAAS, the science society, the world’s largest general scientific organization.

    This work was supported by the U.S. Department of Energy’s Office of Science (Office of Nuclear Physics), the U.S. National Science Foundation, Israel Science Foundation, Chilean Comisión Nacional de Investigación Científica y Technológica, French Centre National de la Recherche Scientifique and Commissariat a l’Energie Atomique, French-American Cultural Exchange, Italian Istituto Nazionale di Fisica Nucleare, National Research Foundation of Korea and the U.K.’s Science and Technology Facilities Council. CEBAF is a DOE Office of Science User Facility.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

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  • richardmitnick 5:26 pm on August 25, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory,   

    From Argonne Lab: “Argonne, KAERI to develop prototype nuclear reactor “ 

    News from Argonne National Laboratory

    August 25, 2014
    No Writer Credit

    The U.S. Department of Energy’s Argonne National Laboratory has teamed up with the Korea Atomic Energy Research Institute (KAERI) to develop the Prototype Generation-IV Sodium-cooled Fast Reactor (PGSFR). KAERI’s Sodium-cooled Fast Reactor Development Agency has provided $6.78 million funding to date for Argonne’s contributions through a Work-for-Others contract.

    lkaeri
    Argonne will support the Korean Atomic Energy Research Institute’s development of a Prototype Generation-IV Sodium-cooled Fast Reactor that incorporates an innovative metal fuel developed at Argonne. The fuel’s inherent safety potential was demonstrated in landmark tests conducted on the Experimental Breeder Reactor-II. Image credit: KAER I.

    Jong Kyung Kim, President of KAERI, visited Argonne today to execute the memorandum of understanding between KAERI and Argonne for a broad field of technical cooperation on nuclear science and technology, including the PGSFR project. “The technical cooperation between KAERI and Argonne plays a critical role in advancing cutting-edge technologies in nuclear energy,” said Argonne Director Peter Littlewood.

    The PGSFR is a 400 MWth, 150 MWe advanced sodium-cooled fast reactor that incorporates many innovative design features; in particular, metal fuel, which enables inherent safety characteristics. With Argonne support, KAERI is developing the reactor system while the Korean engineering and construction firm KEPCO E&C is designing the balance of the plant. The PGSFR Project aims to secure the Korean licensing authority’s design approval by the end of 2020, and the schedule calls for PGSFR to be commissioned by the end of 2028.

    The metal fuel technology base was developed at Argonne in the 1980s and ‘90s; its inherent safety potential was demonstrated in the landmark tests conducted on the Experimental Breeder Reactor-II in April 1986. They demonstrated the safe shutdown and cooling of the reactor without operator action following a simulated loss-of-cooling accident.

    “We are very excited about our collaboration on the PGSFR,” said Mark Peters, Argonne’s Associate Laboratory Director for Energy Engineering and Systems Analysis. “PGSFR is the world’s first new fast reactor that will use the technology developed at Argonne, and also the world’s first fast reactor that exploits inherent safety characteristics to prevent severe accidents.”

    The Argonne-KAERI collaboration on PGSFR was established following the U.S. Government authorization of the 10 CFR Part 810 request to transfer sodium-cooled fast reactor and low-enriched uranium fuel technology to the Republic of Korea.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus

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  • richardmitnick 4:07 pm on August 25, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory, , , University of Chicago   

    From Argonne Lab: “Gut bacteria that protect against food allergies identified” 

    News from Argonne National Laboratory

    August 25, 2014
    This story was first reported by the University of Chicago Medicine and Biological Sciences.

    The presence of Clostridia, a common class of gut bacteria, protects against food allergies, a new study in mice finds. By inducing immune responses that prevent food allergens from entering the bloodstream, Clostridia minimize allergen exposure and prevent sensitization – a key step in the development of food allergies. The discovery points toward probiotic therapies for this so-far untreatable condition, report scientists from the University of Chicago, Aug. 25 in the Proceedings of the National Academy of Sciences.

    clos
    One variety of many of Clostridia

    “From a basic science perspective, what is fascinating with this research is the fine-scale machinations that the host microbiome exhibits with its host,” said Dionysios Antonopoulos of the Institute for Genomics and Systems Biology at Argonne National Laboratory and a co-author for the study. “Specific populations of microorganisms serve specific functions in mediating how the host’s immune system senses and interacts with its environment. As with this study, understanding how specific populations of the microbial community are impacted by antibiotics or diet provides a guide on what therapeutic strategies need to be developed to restore a healthy state.”

    Although the causes of food allergy – a sometimes deadly immune response to certain foods – are unknown, studies have hinted that modern hygienic or dietary practices may play a role by disturbing the body’s natural bacterial composition. In recent years, food allergy rates among children have risen sharply – increasing approximately 50 percent between 1997 and 2011 – and studies have shown a correlation to antibiotic and antimicrobial use.

    “Environmental stimuli such as antibiotic overuse, high fat diets, caesarean birth, removal of common pathogens and even formula feeding have affected the microbiota with which we’ve co-evolved,” said study senior author Cathryn Nagler, PhD, Bunning Food Allergy Professor at the University of Chicago. “Our results suggest this could contribute to the increasing susceptibility to food allergies.”

    To test how gut bacteria affect food allergies, Nagler and her team investigated the response to food allergens in mice. They exposed germ-free mice (born and raised in sterile conditions to have no resident microorganisms) and mice treated with antibiotics as newborns (which significantly reduces gut bacteria) to peanut allergens. Both groups of mice displayed a strong immunological response, producing significantly higher levels of antibodies against peanut allergens than mice with normal gut bacteria.

    This sensitization to food allergens could be reversed, however, by reintroducing a mix of Clostridia bacteria back into the mice. Reintroduction of another major group of intestinal bacteria, Bacteroides, failed to alleviate sensitization, indicating that Clostridia have a unique, protective role against food allergens.

    Closing the door

    To identify this protective mechanism, Nagler and her team studied cellular and molecular immune responses to bacteria in the gut. Genetic analysis revealed that Clostridia caused innate immune cells to produce high levels of interleukin-22 (IL-22), a signaling molecule known to decrease the permeability of the intestinal lining.

    Antibiotic-treated mice were either given IL-22 or were colonized with Clostridia. When exposed to peanut allergens, mice in both conditions showed reduced allergen levels in their blood, compared to controls. Allergen levels significantly increased, however, after the mice were given antibodies that neutralized IL-22, indicating that Clostridia-induced IL-22 prevents allergens from entering the bloodstream.

    “We’ve identified a bacterial population that protects against food allergen sensitization,” Nagler said. “The first step in getting sensitized to a food allergen is for it to get into your blood and be presented to your immune system. The presence of these bacteria regulates that process.” She cautions, however, that these findings likely apply at a population level, and that the cause-and-effect relationship in individuals requires further study.

    While complex and largely undetermined factors such as genetics greatly affect whether individuals develop food allergies and how they manifest, the identification of a bacteria-induced barrier-protective response represents a new paradigm for preventing sensitization to food. Clostridia bacteria are common in humans and represent a clear target for potential therapeutics that prevent or treat food allergies. Nagler and her team are working to develop and test compositions that could be used for probiotic therapy and have filed a provisional patent.

    “It’s exciting because we know what the bacteria are; we have a way to intervene,” Nagler said. “There are of course no guarantees, but this is absolutely testable as a therapeutic against a disease for which there’s nothing. As a mom, I can imagine how frightening it must be to worry every time your child takes a bite of food.”

    “Food allergies affect 15 million Americans, including one in 13 children, who live with this potentially life-threatening disease that currently has no cure,” said Mary Jane Marchisotto, senior vice president of research at Food Allergy Research & Education. “We have been pleased to support the research that has been conducted by Dr. Nagler and her colleagues at the University of Chicago.”

    The study, Commensal bacteria protect against food allergen sensitization, was supported by Food Allergy Research & Education (FARE) and the University of Chicago Digestive Diseases Research Core Center. Gene sequencing was conducted at the Next-Generation Sequencing Core at Argonne National Labortory. Additional authors include Andrew T. Stefka, Taylor Feehley, Prabhanshu Tripathi, Ju Qiu, Kathy D. McCoy, Sarkis K. Mazmanian, Melissa Y. Tjota, Goo-Young Seo, Severine Cao, Betty R. Theriault, Dionysios A. Antonopoulos, Liang Zhou, Eugene B. Chang and Yang-Xin Fu.

    Food Allergy Research & Education (FARE) is a 501(c)(3) nonprofit organization that seeks to find a cure for food allergies while keeping affected individuals safe and included. FARE does this by investing in world-class research that advances the treatment and understanding of the disease, providing evidence-based education and resources, undertaking advocacy at all levels of government and increasing awareness of food allergy as a serious public health issue.

    The University of Chicago Medicine and Biological Sciences is one of the nation’s leading academic medical institutions. It comprises the Pritzker School of Medicine, a top medical school in the nation; the University of Chicago Biological Sciences Division; and the University of Chicago Medical Center, which recently opened the Center for Care and Discovery, a $700 million specialty medical facility. Twelve Nobel Prize winners in physiology or medicine have been affiliated with the University of Chicago Medicine.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus

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  • richardmitnick 9:32 am on July 26, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory,   

    From Argonne Lab: “Silicene: To be or not to be?” 

    News from Argonne National Laboratory

    July 24, 2014
    Justin H.S. Breaux

    Sometimes, scientific findings can shake the foundations of what was once held to be true, causing us to step back and re-examine our basic assumptions.

    A recent study at the U.S. Department of Energy’s Argonne National Laboratory has called into question the existence of silicene, thought to be one of the world’s newest and hottest two-dimensional nanomaterials. The study may have great implications to a multi-billion dollar electronics industry that seeks to revolutionize technology at scales 80,000 times smaller than the human hair.

    sil
    The Structure of a typical silicene cluster showing the ordered ripples across the surface. The valencies for the side atoms are satisfied by hydrogens.

    Silicene was proposed as a two-dimensional sheet of silicon atoms that can be created experimentally by super-heating silicon and evaporating atoms onto a silver platform. Silver is the platform of choice because it will not affect the silicon via chemical bonding nor should alloying occur due to its low solubility. During the heating process, as the silicon atoms fall onto the platform, researchers believed that they were arranging themselves in certain ways to create a single sheet of interlocking atoms.

    Silicon, on the other hand, exists in three dimensions and is one of the most common elements on Earth. A metal, semiconductor and insulator, purified silicon is extremely stable and has become essential to the integrated circuits and transistors that run most of our computers.

    Both silicene and silicon should react immediately with oxygen, but they react slightly differently. In the case of silicon, oxygen breaks some of the silicon bonds of the first one or two atomic layers to form a layer of silicon-oxygen. This, surprisingly, acts a chemical barrier to prevent the decay of the lower layers.

    Because it consists of only one layer of silicon atoms, silicene must be handled in a vacuum. Exposure to any amount of oxygen would completely destroy the sample.

    This difference is one of the keys to the researchers’ discovery. After depositing the atoms onto the silver platform, initial tests identified that alloy-like surface phases would form until bulk silicon layers, or “platelets” would precipitate out, which has been mistaken as two-dimensional silicene.

    “Some of the bulk silicon platelets were more than one layer thick,” said Argonne scientist Nathan Guisinger of Argonne’s Center for Nanoscale Materials. “We determined that if we were dealing with multiple layers of silicon atoms, we could bring it out of our ultra-high vacuum chamber and bring it into air and do some other tests.”

    image
    Argonne researchers use an e-beam evaporator to deposit atomic silicon onto a silver platform in a vacuum. The silver is heated to ~400 C allowing the deposits to rearrange into a sheet of interlocking silicon atoms. The B&W cross-sectional transmission electron microscope image to the right shows the growth of bulk-like silicon nanosheets, rather than atomically thin silicene layers.

    “Everybody assumed the sample would immediately decay as soon as they pulled it out of the chamber,” added Northwestern University graduate student Brian Kiraly, one of the principal authors of the study. “We were the first to actually bring it out and perform major experiments outside of the vacuum.”

    four
    A recent Argonne study has called into question the existence of silicene, thought to be one of the world’s newest and hottest two-dimensional nanomaterials. Pictured are researchers (clockwise from bottom left) Nathan Guisinger, Andrew J. Mannix, Brian Kiraly and Brandon L. Fisher. Photo credit: Wes Agresta, Argonne National Laboratory

    Each new series of experiments presented a new set of clues that this was, in fact, not silicene.

    By examining and categorizing the top layers of the material, the researchers discovered silicon oxide, a sign of oxidation in the top layers. They were also surprised to find that particles from the silver platform alloyed with the silicon at significant depths.

    tunnel
    Researchers at Argonne find that silicene, a one-atom thick sheet of silicon, has not been experimentally realized on silver, and that silver is unlikely to be a good substrate for silicene. (a) This three-dimensional scanning tunneling microscopy image shows the growth of seven ultra-thin layers of silicon nanosheets atop a silver crystal. The atomic structures of the nanosheets are illustrated for layers 4, 5 and 6. (b) Step heights for silicon nanosheets are plotted at the bottom.

    “We found out that what previous researchers identified as silicene is really just a combination of the silicon and the silver,” said Northwestern graduate student Andrew Mannix.

    For their final test, the researchers decided to probe the atomic signature of the material.

    Materials are made up of systems of atoms that bond and vibrate in unique ways. Raman spectroscopy allows researchers to measure these bonds and vibrations. Housed within the Center for Nanoscale Materials, a DOE Office of Science User Facility, the spectroscope allows researchers to use light to “shift” the position of one atom in a crystal lattice, which in turn causes a shift in the position of its neighbors. Scientists define a material by measuring how strong or weak these bonds are in relation to the frequency at which the atoms vibrate.

    The researchers noticed something oddly familiar when looking at the vibrational signatures and frequencies of their sample. Their sample did not exhibit characteristic vibrations of silicene, but it did match those of silicon.

    “Having this many research groups and papers potentially be wrong does not happen often,” says Guisinger. “I hope our research helps guide future studies and convincingly demonstrates that silver is not a good platform if you are trying to grow silicene.”

    This material is based upon work supported by the U.S. Department of Energy’s Office of Science.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus


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  • richardmitnick 6:18 am on July 16, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory, Combustion studies   

    From Argonne Lab: “New Argonne initiative to examine the details of the combustion process” 

    News from Argonne National Laboratory

    July 15, 2014
    Jared Sagoff

    Every science experiment and every mathematical model faces the same challenge: uncertainty.

    A complex system like an engine has many parameters that must be included in any reliable simulation. From fuel injectors to combustion chemistry, every part of the process of combustion has parameters with some level of uncertainty associated with them. These uncertainties are often extremely difficult for scientists to reduce. The field of uncertainty analysis provides the tools to investigate how parameter uncertainty influences simulation outcomes.

    comb
    Researchers at Argonne, as part of the new Virtual Engine Research Institute and Fuels Initiative (VERIFI), are looking at a number of parameters in the internal combustion process. VERIFI is the first and only source in the world for high-fidelity, three-dimensional, end-to-end combustion engine simulation/visualization and simultaneous powertrain and fuel simulation, with uncertainty analysis.

    A team of researchers from the U.S. Department of Energy’s Argonne National Laboratory is using a specific form of uncertainty analysis called global sensitivity analysis (GSA), which breaks down the uncertainty into constitute parts.

    “There are lots of unknowns that are involved,” said mechanical engineer Sibendu Som of the U.S. Department of Energy’s (DOE) Argonne National Laboratory. “We’re using sensitivity analysis to understand how they all affect overall uncertainty.”

    Researchers at Argonne, as part of the new Virtual Engine Research Institute and Fuels Initiative (VERIFI), are looking at a number of parameters in the internal combustion process. VERIFI is the first and only source in the world for high-fidelity, three-dimensional, end-to-end combustion engine simulation/visualization and simultaneous powertrain and fuel simulation, with uncertainty analysis.

    The parameters being investigated include the relationships between the diameter of the nozzle in the fuel injector, the dynamics of the fuel spray, the proportion of fuel to air in the combustion chamber and the exhaust products. By gaining a better understanding of how these parameter uncertainties affect outcomes, the VERIFI researchers seek to create cleaner and more efficient engines.

    Overall, Som and Argonne mechanical engineer Yuanjiang Pei and chemist Michael Davis have investigated 32 different parameters simultaneously, trying to establish how the uncertainties vary under different conditions. “If we can find a way to understand how uncertainty effects our simulations, we can take a step toward developing a more predictive simulation,” Som said.

    Building on several decades of work by chemists, statisticians, and applied mathematicians, Argonne chemists have developed the tools to apply GSA to large chemical models in collaboration with their colleagues at the University of Colorado and the University of Leeds.

    These techniques were further refined in the last two years to allow their efficient application to engine simulations, leading to the present study, which involves a collaboration with the University of Connecticut. These new methods demonstrate the benefits of close collaboration between basic and applied research. “This is the first time we’ve applied these methods in such a complicated system,” said Argonne mechanical engineer Doug Longman. “We have demonstrated that GSA can be used in a systematic way for something as complex as an engine simulation.”

    In particular, VERIFI researchers are taking an iterative approach in which data gathered from the simulations can be fed back to both engine modelers and combustion chemists to further reduce uncertainty and create more predictive engine simulations. “What’s unique about VERIFI is the way we’ve refined the tools to create engine simulations that are more reliable and applied high-performance computing resources to run simulations faster and more intensively than ever before,” Som said.

    By taking advantage of the incredible computational power available today, the VERIFI team can identify the most important engine and fuel parameters and develop unique engine simulations and analyses to enable optimized engine combustion in the presence of uncertainty at any operating condition. In the near future, the VERIFI team plans to run diesel engine simulations of unprecedented scale on Mira, Argonne’s 10-petaflop IBM Blue Gene/Q supercomputer.

    Funding for this work is provided by DOE’s Office of Energy Efficiency and Renewable Energy and the Office of Basic Energy Sciences within DOE’s Office of Science.

    See the full article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus


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  • richardmitnick 6:33 pm on June 30, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory,   

    From Argonne Lab: “Microscopy charges ahead” 

    News from Argonne National Laboratory

    May 28, 2014
    Jared Sagoff

    Ferroelectric materials – substances in which there is a slight and reversible shift of positive and negative charges – have surfaces that are coated with electrical charges like roads covered in snow. Accumulations can obscure lane markings, making everyone unsure which direction traffic ought to flow; in the case of ferroelectrics, these accumulations are other charges that “screen” the true polarization of different regions of the material.

    Ferroelectric materials are of special interest to researchers as a potential new form of computer memory and for sensor technologies.

    two
    Argonne materials scientists Seungbum Hong (left) and Andreas Roelofs adjust an atomic force microscope.Photo credit: Wes Agresta/Argonne National Laboratory.

    In order to see this true polarization quickly and efficiently, researchers at the U.S. Department of Energy’s Argonne National Laboratory have developed a new technique called charge gradient microscopy. Charge gradient microscopy uses the tip of a conventional atomic force microscope to scrape and collect the surface screen charges.

    “The whole process works much like a snowplow scraping along the roads,” said Argonne materials scientist Seungbum Hong, who led the research. “Before, all we had was a snowshovel.”

    Ferroelectric materials are not usually polarized in any particular way, but they are rather the combination of different domains that are each polarized in different directions. “The end goal of the research is to be able to map these different regions quickly and accurately,” Hong said.

    “Until now, the process of trying to map these regions has been incredibly arduous and time-consuming,” added Argonne Nanoscience and Technology interim division director Andreas Roelofs, who came up with the idea for the study. “What was taking us 10 to 15 minutes now takes seconds.”

    Previous efforts in this arena had focused on the application of a different kind of microscope using piezoresponse force microscopy (PFM). In this technique, an applied voltage causes a small displacement of atoms in the material, generating a noticeable mechanical effect, or vibration. In reverse, the same phenomenon is responsible for the workings of the lighters in gas grills.

    The problem with PFM is that it is very slow and requires sophisticated equipment to measure a tiny motion of the material. “Before, we had to sit on one spot for a long time to get enough signal to understand how the material moves because we could just barely sense it,” Roelofs said. “For the past 15 years or so, we’ve tried to increase the speed of the measurements and made only modest progress while adding a lot of complexity.”

    “Now, everyone can use a standard tool to do this work much more cheaply and efficiently,” he added.

    An article based on the study appears in the April 23 early edition of the Proceedings of the National Academy of Sciences.

    This research was funded by the U.S. Department of Energy’s Office of Science.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus


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  • richardmitnick 5:47 pm on June 9, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory,   

    From Argonne Lab: “Neutrons and X-rays reveal structure of high-temperature liquid metal oxides” 

    News from Argonne National Laboratory

    June 9, 2014
    Tona Kunz

    Neutrons and X-rays reveal structure of high-temperature liquid metal oxides
    By Tona Kunz • June 9, 2014
    inShare
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    By levitating a bead of ceramic oxide, heating it with a 400-watt carbon dioxide laser, then shooting the molten material with X-rays and neutrons, scientists with the U.S. Department of Energy’s Oak Ridge and Argonne national laboratories have revealed unprecedented detail of the structure of high-temperature liquid oxides.

    levit
    A metal oxide drop levitated in a flow of gas is heated from above with a laser beam so that researchers can study the behavior of this class of ceramics under high temperatures. Image courtesy of Spallation Neutron Source at Oak Ridge National Laboratory. Click to enlarge.

    This class of ceramics is often used to resist high temperatures, but its behavior under extreme temperatures is also critical for understanding the evolution of planetary bodies, nuclear meltdown scenarios, and glass formation.

    In a study published in Physical Review Letters, researchers from Stony Brook University joined forces with colleagues at Oak Ridge and Argonne scientific user facilities to study the structure and properties of high melting point non-glass forming oxide liquids, such as yttrium and holmium oxides.

    The research team observed a general trend towards lower metal and oxygen coordination in a wide range of oxide melts, suggesting that this behavior is a widely occurring phenomenon. The structure of oxide melts determines most of their physical properties, which in turn are directly relevant to planetary research as well as glass making and crystal growth processes including laser garnets and display phosphors.

    “In principle, with this knowledge we could make new families of materials by capturing unusual structural motifs present in the melt that don’t occur in the crystal,” said Chris Benmore, physicist at Argonne’s Advanced Photon Source. “We want to find out how to stabilize that structure – maybe by adding components or through vitrifying the melt – and end up with same material, but with different properties.”

    By combining the analysis of separate X-ray and neutron diffraction experiments, the researchers made the first determination of the complete set of pair distribution functions for a high temperature oxide melt, which gives element-specific information on the probability of finding two atoms with a given separation distance. These separation probabilities provide specific information on local coordination and connectivity, such as between the metal and oxygen atoms, which helps scientists understand physical properties such as density, viscosity, and conductivity.

    “Neutrons show us the oxygens in the material clearly, while X-rays reveal the cations [positively charged atoms],” said Benmore. “If you want to extract the detailed structure, you need both techniques.”

    Joerg Neuefeind, instrument scientist at Oak Ridge’s Spallation Neutron Source, said, “There’s no way with one experiment to get that information.” Neuefeind explained that the experiment required not only collaboration among the two DOE labs, but also a unique sample environment to reach temperatures exceeding 3,000 degrees kelvin, or almost 5,000 degrees Fahrenheit.

    For perspective, Neuefeind added, steel melts at approximately 2,600 degrees Fahrenheit, while 6,700 degrees Fahrenheit is the melting point of diamond and 10,300 degrees Fahrenheit is the surface temperature of the sun.

    The sample environment where the liquid metal oxide was measured involves a levitation system and a laser. The levitation system is made of a special nozzle designed to produce a gas flow that can trap a small bead of material–about an eighth of an inch in diameter─ “floating in air” above the nozzle. The levitation ensures the sample is not in contact with any solid surface that would melt, react with, and contaminate the sample at these temperatures, while a laser is used to heat the sample as it floats on the gas flow. Richard Weber, owner of Materials Development Inc. in Arlington Heights, Illinois, has collaborated with this research team for many years to develop the levitation system and optimize the method.

    The research was supported by the Department of Energy’s Office of Science, and was conducted at two DOE Office of Science user facilities: the Advanced Photon Source at Argonne National Laboratory and the Spallation Neutron Source at Oak Ridge National Laboratory. Support was also provided by DOE’s Small Business Innovation Research program.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus


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  • richardmitnick 7:34 pm on May 29, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory,   

    From Argonne Lab: “Flexible, transparent thin film transistors raise hopes for flexible screens” 

    News from Argonne National Laboratory

    May 23, 2014
    Louise Lerner

    The electronics world has been dreaming for half a century of the day you can roll a TV up in a tube. Last year, Samsung even unveiled a smartphone with a curved screen—but it was solid, not flexible; the technology just hasn’t caught up yet.

    But scientists got one step closer last month when researchers at the U.S. Department of Energy’s Argonne National Laboratory reported the creation of the world’s thinnest flexible, see-through 2-D thin film transistors.

    four
    Scientists from Argonne created the world’s thinnest flexible, transparent thin-film transistor, which could one day be useful in making a truly flexible display screen for TVs or phones. From left: Andreas Roelofs, Anirudha Sumant, and Richard Gulotty; in foreground, Saptarshi Das. Photo by Mark Lopez/Argonne National Laboratory

    These transistors are just 10 atomic layers thick—that’s about how much your fingernails grow per second.

    image
    The thin-film transistor is flexible, transparent and performs just as well as commercial versions. Displayed is an array of transistors – each of which are just 10 atomic layers thick. Photo by Mark Lopez/Argonne National Laboratory.

    Transistors are the basis of nearly all electronics. Their two settings—on or off—dictate the 1s and 0s of computer binary language. Thin film transistors are a particular subset of these that are typically used in screens and displays. Virtually all flat-screen TVs and smartphones are made up of thin film transistors today; they form the basis of both LEDs and LCDs (liquid crystal displays).

    “This could make a transparent, nearly invisible screen,” said Andreas Roelofs, a coauthor on the paper and interim director of Argonne’s Center for Nanoscale Materials. “Imagine a normal window that doubles as a screen whenever you turn it on, for example.”

    image2
    A scanning electron microscope image of the thin-film transistor, fabricated using single-atom-thick layers of graphene and tungsten diselenide, among other materials. The white scale bar shows 5 microns, which is about the diameter of a strand of spider silk. Image courtesy Saptarshi Das.

    To measure how good a transistor is, you measure its on-off ratio—how completely can it turn off the current?—and a property called “field effect carrier mobility,” which measures how quickly electrons can move through the material.

    “We were pleased to find that the on/off ratio is just as good as current commercial thin-film transistors,” said Argonne postdoctoral scientist and first author Saptarshi Das, “but the mobility is a hundred times better than what’s on the market today.”

    two
    Graduate student Richard Gulotty (left) and Argonne scientist Saptarshi Das examine thin-film transistors in the clean room at Argonne’s Center for Nanoscale Materials. The clean room allows scientists to create precisely layered and uncontaminated samples of materials, such as these transistors. Photo by Mark Lopez/Argonne National Laboratory.

    The team also tried bending the films to test what happens under stress. In most thin film transistors, the material starts to crack, which, as you might imagine, affects performance. “But in ours, the properties didn’t change at all,” Roelofs said. “The layers just slide and don’t crack.”

    image3
    Argonne scientist Anirudha Sumant (left) and graduate student Richard Gulotty use facilities at Argonne’s Center for Nanoscale Materials to fabricate extremely thin layers of graphene and tungsten selenide, among other materials. 10 atomic layers built the world’s thinnest, flexible, transparent thin-film transistors, which have excellent performance. Photo by Mark Lopez/Argonne National Laboratory.

    The transistors also maintained performance over a wide range of temperatures (from -320°F to 250°F), a useful property in electronics, which can run very hot.

    To build the transistors, the team started with a trick that earned its original University of Manchester inventors the Nobel Prize: using a strip of scotch tape to peel off a sheet of tungsten diselenide just atoms thick.

    “We chose tungsten diselenide because it provides the electron and hole conduction necessary for making transistors with logic gates and other p-n junction devices,” said Argonne scientist and coauthor Anirudha Sumant.

    Then they used chemical deposition to grow sheets of other materials on top to build the transistor layer by layer. The final product is 10 atomic layers thick.

    Next, the team is interested in adding logic and memory to flexible films, so you could make not just a screen but an entire flexible and transparent TV or computer.

    “However, more work needs to be done in developing large-area synthesis of tungsten diselenide to realize the true potential for applications of our work,” said Sumant.

    The study, All Two-Dimensional, Flexible, Transparent, and Thinnest Thin Film Transistor, was published in Nano Letters. The other author on the study was graduate student Richard Gulotty. The work is a collaborative effort between the High Energy Physics and Nanoscience and Technology divisions at Argonne, based on the idea that multi-disciplinary research projects structured to address grand science challenges could expedite technological progress for all disciplines.

    The Center for Nanoscale Materials, where the work was conducted, is supported by the U.S. Department of Energy’s Office of Science.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus


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  • richardmitnick 9:00 pm on May 28, 2014 Permalink | Reply
    Tags: , Argonne National Laboratory,   

    From Argonne Lab: “Microscopy charges ahead: 

    News from Argonne National Laboratory

    May 28, 2014
    Jared Sagoff

    Ferroelectric materials – substances in which there is a slight and reversible shift of positive and negative charges – have surfaces that are coated with electrical charges like roads covered in snow. Accumulations can obscure lane markings, making everyone unsure which direction traffic ought to flow; in the case of ferroelectrics, these accumulations are other charges that “screen” the true polarization of different regions of the material.

    Ferroelectric materials are of special interest to researchers as a potential new form of computer memory and for sensor technologies.

    In order to see this true polarization quickly and efficiently, researchers at the U.S. Department of Energy’s Argonne National Laboratory have developed a new technique called charge gradient microscopy. Charge gradient microscopy uses the tip of a conventional atomic force microscope to scrape and collect the surface screen charges.

    two
    Argonne materials scientists Seungbum Hong (left) and Andreas Roelofs adjust an atomic force microscope. Click to enlarge. Photo credit: Wes Agresta/Argonne National Laboratory.

    “The whole process works much like a snowplow scraping along the roads,” said Argonne materials scientist Seungbum Hong, who led the research. “Before, all we had was a snowshovel.”

    Ferroelectric materials are not usually polarized in any particular way, but they are rather the combination of different domains that are each polarized in different directions. “The end goal of the research is to be able to map these different regions quickly and accurately,” Hong said.

    “Until now, the process of trying to map these regions has been incredibly arduous and time-consuming,” added Argonne Nanoscience and Technology interim division director Andreas Roelofs, who came up with the idea for the study. “What was taking us 10 to 15 minutes now takes seconds.”

    Previous efforts in this arena had focused on the application of a different kind of microscope using piezoresponse force microscopy (PFM). In this technique, an applied voltage causes a small displacement of atoms in the material, generating a noticeable mechanical effect, or vibration. In reverse, the same phenomenon is responsible for the workings of the lighters in gas grills.

    The problem with PFM is that it is very slow and requires sophisticated equipment to measure a tiny motion of the material. “Before, we had to sit on one spot for a long time to get enough signal to understand how the material moves because we could just barely sense it,” Roelofs said. “For the past 15 years or so, we’ve tried to increase the speed of the measurements and made only modest progress while adding a lot of complexity.”

    “Now, everyone can use a standard tool to do this work much more cheaply and efficiently,” he added.

    An article based on the study appears in the April 23 early edition of the Proceedings of the National Academy of Sciences.

    This research was funded by the U.S. Department of Energy’s Office of Science.

    See the full article here.

    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit http://science.energy.gov/user-facilities/basic-energy-sciences/.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus


    ScienceSprings is powered by MAINGEAR computers

     
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