2011 Nobel Prize in Chemistry: 'Quasicrystals' once thought impossible have changed understanding of solid matter

ScienceDaily (Oct. 5, 2011) — The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Chemistry for 2011 to Daniel Shechtman of the Technion -- Israel Institute of Technology in Haifa, Israel, for the discovery of quasicrystals: non-repeating regular patterns of atoms that were once thought to be impossible.

A remarkable mosaic of atoms

In quasicrystals, we find the fascinating mosaics of the Arabic world reproduced at the level of atoms: regular patterns that never repeat themselves. However, the configuration found in quasicrystals was considered impossible, and Daniel Shechtman had to fight a fierce battle against established science. The Nobel Prize in Chemistry 2011 recognizes a breakthrough that has fundamentally altered how chemists conceive of solid matter.

On the morning of April 8, 1982, an image counter to the laws of nature appeared in Daniel Shechtman's electron microscope. In all solid matter, atoms were believed to be packed inside crystals in symmetrical patterns that were repeated periodically over and over again. For scientists, this repetition was required in order to obtain a crystal.

Shechtman's image, however, showed that the atoms in his crystal were packed in a pattern that could not be repeated. Such a pattern was considered just as impossible as creating a football using only six-cornered polygons, when a sphere needs both five- and six-cornered polygons. His discovery was extremely controversial. In the course of defending his findings, he was asked to leave his research group. However, his battle eventually forced scientists to reconsider their conception of the very nature of matter.

Aperiodic mosaics, such as those found in the medieval Islamic mosaics of the Alhambra Palace in Spain and the Darb-i Imam Shrine in Iran, have helped scientists understand what quasicrystals look like at the atomic level. In those mosaics, as in quasicrystals, the patterns are regular -- they follow mathematical rules -- but they never repeat themselves.

When scientists describe Shechtman's quasicrystals, they use a concept that comes from mathematics and art: the golden ratio. This number had already caught the interest of mathematicians in Ancient Greece, as it often appeared in geometry. In quasicrystals, for instance, the ratio of various distances between atoms is related to the golden mean.

Following Shechtman's discovery, scientists have produced other kinds of quasicrystals in the lab and discovered naturally occurring quasicrystals in mineral samples from a Russian river. A Swedish company has also found quasicrystals in a certain form of steel, where the crystals reinforce the material like armor. Scientists are currently experimenting with using quasicrystals in different products such as frying pans and diesel engines.

Daniel Shechtman, Israeli citizen. Born 1941 in Tel Aviv, Israel. Ph.D. 1972 from Technion -- Israel Institute of Technology, Haifa, Israel. Distinguished Professor, The Philip Tobias Chair, Technion -- Israel Institute of Technology, Haifa, Israel.

The Prize amount: SEK 10 million.

For further information, including backgrounders for the public and scientists and links for further reading, see: http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2011/press.html

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Nobel Foundation.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Splitting water for renewable energy simpler than first thought? Manganese-based catalyst shows promise

ScienceDaily (May 18, 2011) — An international team, of scientists, led by a team at Monash University has found the key to the hydrogen economy could come from a very simple mineral, commonly seen as a black stain on rocks.

Their findings, developed with the assistance of researchers at UC Davis in the USA and using the facilities at the Australian Synchrotron, was published in the journal Nature Chemistry on May 15, 2011.

Professor Leone Spiccia from the School of Chemistry at Monash University said the ultimate goal of researchers in this area is to create a cheap, efficient way to split water, powered by sunlight, which would open up production of hydrogen as a clean fuel, and leading to long-term solutions for our renewable energy crisis.

To achieve this, they have been studying complex catalysts designed to mimic the catalysts plants use to split water with sunlight. But the new study shows that there might be much simpler alternatives to hand.

"The hardest part about turning water into fuel is splitting water into hydrogen and oxygen, but the team at Monash seems to have uncovered the process, developing a water-splitting cell based on a manganese-based catalyst," Professor Spiccia said.

"Birnessite, it turns out, is what does the work. Like other elements in the middle of the Periodic Table, manganese can exist in a number of what chemists call oxidation states. These correspond to the number of oxygen atoms with which a metal atom could be combined," Professor Spiccia said.

"When an electrical voltage is applied to the cell, it splits water into hydrogen and oxygen and when the researchers carefully examined the catalyst as it was working, using advanced spectroscopic methods they found that it had decomposed into a much simpler material called birnessite, well-known to geologists as a black stain on many rocks."

The manganese in the catalyst cycles between two oxidation states. First, the voltage is applied to oxidize from the manganese-II state to manganese-IV state in birnessite. Then in sunlight, birnessite goes back to the manganese-II State.

This cycling process is responsible for the oxidation of water to produce oxygen gas, protons and electrons.

Co-author on the research paper was Dr Rosalie Hocking, Research Fellow in the Australian Centre for Electromaterials Science who explained that what was interesting was the operation of the catalyst, which follows closely natures biogeochemical cycling of manganese in the oceans.

"This may provide important insights into the evolution of Nature's water splitting catalyst found in all plants which uses manganese centres," Dr Hocking said.

"Scientists have put huge efforts into making very complicated manganese molecules to copy plants, but it turns out that they convert to a very common material found in the Earth, a material sufficiently robust to survive tough use."

The reaction has two steps. First, two molecules of water are oxidized to form one molecule of oxygen gas (O2), four positively-charged hydrogen nuclei (protons) and four electrons. Second, the protons and electrons combine to form two molecules of hydrogen gas (H2).

The experimental work was conducted using state-of-the art equipment at three major facilities including the Australian Synchrotron, the Australian National Beam-line Facility in Japan and the Monash Centre for Electron Microscopy, and involved collaboration with Professor Bill Casey, a geochemist at UC Davis.

"The research highlights the insight obtainable from the synchrotron based spectroscopic techniques -- without them the important discovery linking common earth materials to water oxidation catalysts would not have been made," Dr Hocking said.

It is hoped the research will ultimately lead to the development of cheaper devices, which produce hydrogen.

The work was primarily funded by the U.S. National Science Foundation and the U.S. Department of Energy Monash University, the Australian Research Council through the Australian Centre of Excellence for Electromaterials Science, and the Australian Synchrotron.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Monash University.

Journal Reference:

Rosalie K. Hocking, Robin Brimblecombe, Lan-Yun Chang, Archana Singh, Mun Hon Cheah, Chris Glover, William H. Casey, Leone Spiccia. Water-oxidation catalysis by manganese in a geochemical-like cycle. Nature Chemistry, 2011; DOI: 10.1038/nchem.1049

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Imaging of surface plasmons may be a lot easier than previously thought

ScienceDaily (June 6, 2011) — An unusual observation turned into a scientific breakthrough when K.U.Leuven researchers investigating the optical properties of nanomaterials discovered that so-called surface plasmons leave imprints on the surface of the nanostructures. This led to a new type of high resolution microscopy for imaging the electric fields of nanostructures.

Nanomaterials, consisting of extremely small particles or thin layers, tend to acquire unexpected properties. Optical nanomaterials are a class of materials that have emerged over the last ten years and that have quickly become a hot topic in material science due to their counterintuitive optical behavior and revolutionary potential applications. Optical nanomaterials are mainly based on surface plasmon resonances -- the property whereby, in metallic nanostructures, light can collectively excite surface electron waves. These electron waves have the same frequency as light, but much shorter wavelengths, which allow their manipulation at the nanoscale. In other words, with the help of plasmons, light can be captured, modified and even stored in nanostructures. This emerging technology finds applications in surprising areas, ranging from cancer treatment (by targeting cancer cells with nanoparticles that will produce heat when excited) to invisibility (by causing light to follow a trail of nanoparticles, that acts as an invisibility cloak to whatever is underneath them).

The imaging of surface plasmons provides a direct way to map and understand the local electric fields that are responsible for the unusual electromagnetic properties of optical nanomaterials. However, the imaging of surface plasmons is quite challenging. While there are methods to image plasmons with high resolution, they come at a considerable increase in both cost and complexity. But now, Ventsislav K. Valev and his colleagues have demonstrated a powerful and user friendly method for imaging plasmonic patterns in nanostructures.

"We were performing routine characterization of freshly grown samples, when I asked Yogesh, one of our Ph.D. students, to look at a sample that had already been studied. There was absolutely no reason to do this; I just had a hunch," sais Ventsislav Valev. "Surprisingly, this sample appeared to be decorated and I immediately recognized the pattern. Somehow, the optical properties have been imprinted on the surface of the nanostructures."

The scientists indeed found out that upon illuminating nanostructures made of nickel or palladium, the resulting surface plasmon pattern is imprinted on the structures themselves. This imprinting is done through displacing material from the nanostructure to the regions where the plasmon enhancements are the largest. In this manner, the plasmons are effectively decorated, allowing for subsequent imaging with standard surface probe techniques, such as scanning electron microscopy or atomic force microscopy. The imprinting method is quite unique, combining aspects of both imaging and writing techniques.

This research is described in an upcoming paper in the journal Physical Review Letters.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Katholieke Universiteit Leuven, via AlphaGalileo.

Journal Reference:

V. Valev, A. Silhanek, Y. Jeyaram, D. Denkova, B. De Clercq, V. Petkov, X. Zheng, V. Volskiy, W. Gillijns, G. Vandenbosch, O. Aktsipetrov, M. Ameloot, V. Moshchalkov, T. Verbiest. Hotspot Decorations Map Plasmonic Patterns with the Resolution of Scanning Probe Techniques. Physical Review Letters, 2011; 106 (22) DOI: 10.1103/PhysRevLett.106.226803

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Splitting water for renewable energy simpler than first thought? Manganese-based catalyst shows promise

ScienceDaily (May 18, 2011) — An international team, of scientists, led by a team at Monash University has found the key to the hydrogen economy could come from a very simple mineral, commonly seen as a black stain on rocks.

Their findings, developed with the assistance of researchers at UC Davis in the USA and using the facilities at the Australian Synchrotron, was published in the journal Nature Chemistry on May 15, 2011.

Professor Leone Spiccia from the School of Chemistry at Monash University said the ultimate goal of researchers in this area is to create a cheap, efficient way to split water, powered by sunlight, which would open up production of hydrogen as a clean fuel, and leading to long-term solutions for our renewable energy crisis.

To achieve this, they have been studying complex catalysts designed to mimic the catalysts plants use to split water with sunlight. But the new study shows that there might be much simpler alternatives to hand.

"The hardest part about turning water into fuel is splitting water into hydrogen and oxygen, but the team at Monash seems to have uncovered the process, developing a water-splitting cell based on a manganese-based catalyst," Professor Spiccia said.

"Birnessite, it turns out, is what does the work. Like other elements in the middle of the Periodic Table, manganese can exist in a number of what chemists call oxidation states. These correspond to the number of oxygen atoms with which a metal atom could be combined," Professor Spiccia said.

"When an electrical voltage is applied to the cell, it splits water into hydrogen and oxygen and when the researchers carefully examined the catalyst as it was working, using advanced spectroscopic methods they found that it had decomposed into a much simpler material called birnessite, well-known to geologists as a black stain on many rocks."

The manganese in the catalyst cycles between two oxidation states. First, the voltage is applied to oxidize from the manganese-II state to manganese-IV state in birnessite. Then in sunlight, birnessite goes back to the manganese-II State.

This cycling process is responsible for the oxidation of water to produce oxygen gas, protons and electrons.

Co-author on the research paper was Dr Rosalie Hocking, Research Fellow in the Australian Centre for Electromaterials Science who explained that what was interesting was the operation of the catalyst, which follows closely natures biogeochemical cycling of manganese in the oceans.

"This may provide important insights into the evolution of Nature's water splitting catalyst found in all plants which uses manganese centres," Dr Hocking said.

"Scientists have put huge efforts into making very complicated manganese molecules to copy plants, but it turns out that they convert to a very common material found in the Earth, a material sufficiently robust to survive tough use."

The reaction has two steps. First, two molecules of water are oxidized to form one molecule of oxygen gas (O2), four positively-charged hydrogen nuclei (protons) and four electrons. Second, the protons and electrons combine to form two molecules of hydrogen gas (H2).

The experimental work was conducted using state-of-the art equipment at three major facilities including the Australian Synchrotron, the Australian National Beam-line Facility in Japan and the Monash Centre for Electron Microscopy, and involved collaboration with Professor Bill Casey, a geochemist at UC Davis.

"The research highlights the insight obtainable from the synchrotron based spectroscopic techniques -- without them the important discovery linking common earth materials to water oxidation catalysts would not have been made," Dr Hocking said.

It is hoped the research will ultimately lead to the development of cheaper devices, which produce hydrogen.

The work was primarily funded by the U.S. National Science Foundation and the U.S. Department of Energy Monash University, the Australian Research Council through the Australian Centre of Excellence for Electromaterials Science, and the Australian Synchrotron.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Monash University.

Journal Reference:

Rosalie K. Hocking, Robin Brimblecombe, Lan-Yun Chang, Archana Singh, Mun Hon Cheah, Chris Glover, William H. Casey, Leone Spiccia. Water-oxidation catalysis by manganese in a geochemical-like cycle. Nature Chemistry, 2011; DOI: 10.1038/nchem.1049

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Once thought a rival phase, antiferromagnetism coexists with superconductivity

ScienceDaily (May 23, 2011) — High-temperature superconductivity can be looked at as a fight for survival at the atomic scale. In an effort to reach that point where electrons pair up and resistance is reduced to zero, superconductivity must compete with numerous, seemingly rival phases of matter.

Understanding those phases and whether or not they are rivals or complementary phenomena has consumed the attention of theoreticians and experimentalists in the quest to find superconducting materials capable of functioning at close-to-room temperature, a potential that has gone unrealized for nearly three decades.

One of those phases, antiferromagnetism (AFM), shows evidence of co-existing with superconductivity under examination by two high-tech procedures for measuring the activity of neutrons and electrons, an international team of physicists report in the current edition of the journal Nature Physics.

The findings add further evidence to the team's earlier discovery that spin excitations -- the dynamic harmonic oscillations of the magnetic moments associated with subatomic particles like electrons -- play a crucial role in superconductivity, said lead author and Boston College Associate Professor of Physics Vidya Madhavan.

The team -- including researchers from Boston College, Chinese Academy of Sciences, National Institute of Standards and Technology, Oak Ridge National Laboratory and the University of Tennessee, -- used neutron scattering and scanning tunneling microscopy to determine the interplay between AFM and superconductivity.

In certain solids, antiferromagnetism exists when adjacent ions -- each bearing a small magnet called a 'spin' -- line up in opposite directions throughout the material, neutralizing its magnetic force. Essentially, the magnetic atoms or ions pointed in one direction cancel out the magnetic atoms or ions pointing in the opposite direction.

Madhavan said all high temperature superconductors are close to the AFM phase. But it has been thought that AFM disappears, giving way to the emergence of superconductivity.

But tests on a copper oxide doped with additional electrons displayed activity that runs counter to the theory that the phases exclude each other, said Madhavan. Instead, AFM remains as superconductivity is reached in the high-temperature superconductor.

"The two phases actually compete and co-exist," said Madhavan. The neutron scattering and scanning tunneling microscopy revealed spin excitations in both modes -- AFM and superconductivity. While neutron scattering can directly probe spin excitations, STM can identify the behavior of the electrons. Together, the evidence shows spin excitations in the electronic spectrum, which signals that electron coupling is taking place.

The experimental evidence is crucial to better understanding superconductivity, Madhavan said.

"These strongly correlated materials are very hard to handle from a theoretical standpoint because there are so many possibilities," said Madhavan. "In this field we need to really understand these materials experimentally because theory is very difficult to do."

This experimental work gives additional evidence that spin excitations are critical to superconductivity, Madhavan said, "and it gives us a deeper understanding of the interplay between various phases."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Boston College, via EurekAlert!, a service of AAAS.

Journal Reference:

Jun Zhao, F. C. Niestemski, Shankar Kunwar, Shiliang Li, P. Steffens, A. Hiess, H. J. Kang, Stephen D. Wilson, Ziqiang Wang, Pengcheng Dai, V. Madhavan. Electron-spin excitation coupling in an electron-doped copper oxide superconductor. Nature Physics, 2011; DOI: 10.1038/nphys2006

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Once thought a rival phase, antiferromagnetism coexists with superconductivity

ScienceDaily (May 23, 2011) — High-temperature superconductivity can be looked at as a fight for survival at the atomic scale. In an effort to reach that point where electrons pair up and resistance is reduced to zero, superconductivity must compete with numerous, seemingly rival phases of matter.

Understanding those phases and whether or not they are rivals or complementary phenomena has consumed the attention of theoreticians and experimentalists in the quest to find superconducting materials capable of functioning at close-to-room temperature, a potential that has gone unrealized for nearly three decades.

One of those phases, antiferromagnetism (AFM), shows evidence of co-existing with superconductivity under examination by two high-tech procedures for measuring the activity of neutrons and electrons, an international team of physicists report in the current edition of the journal Nature Physics.

The findings add further evidence to the team's earlier discovery that spin excitations -- the dynamic harmonic oscillations of the magnetic moments associated with subatomic particles like electrons -- play a crucial role in superconductivity, said lead author and Boston College Associate Professor of Physics Vidya Madhavan.

The team -- including researchers from Boston College, Chinese Academy of Sciences, National Institute of Standards and Technology, Oak Ridge National Laboratory and the University of Tennessee, -- used neutron scattering and scanning tunneling microscopy to determine the interplay between AFM and superconductivity.

In certain solids, antiferromagnetism exists when adjacent ions -- each bearing a small magnet called a 'spin' -- line up in opposite directions throughout the material, neutralizing its magnetic force. Essentially, the magnetic atoms or ions pointed in one direction cancel out the magnetic atoms or ions pointing in the opposite direction.

Madhavan said all high temperature superconductors are close to the AFM phase. But it has been thought that AFM disappears, giving way to the emergence of superconductivity.

But tests on a copper oxide doped with additional electrons displayed activity that runs counter to the theory that the phases exclude each other, said Madhavan. Instead, AFM remains as superconductivity is reached in the high-temperature superconductor.

"The two phases actually compete and co-exist," said Madhavan. The neutron scattering and scanning tunneling microscopy revealed spin excitations in both modes -- AFM and superconductivity. While neutron scattering can directly probe spin excitations, STM can identify the behavior of the electrons. Together, the evidence shows spin excitations in the electronic spectrum, which signals that electron coupling is taking place.

The experimental evidence is crucial to better understanding superconductivity, Madhavan said.

"These strongly correlated materials are very hard to handle from a theoretical standpoint because there are so many possibilities," said Madhavan. "In this field we need to really understand these materials experimentally because theory is very difficult to do."

This experimental work gives additional evidence that spin excitations are critical to superconductivity, Madhavan said, "and it gives us a deeper understanding of the interplay between various phases."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Boston College, via EurekAlert!, a service of AAAS.

Journal Reference:

Jun Zhao, F. C. Niestemski, Shankar Kunwar, Shiliang Li, P. Steffens, A. Hiess, H. J. Kang, Stephen D. Wilson, Ziqiang Wang, Pengcheng Dai, V. Madhavan. Electron-spin excitation coupling in an electron-doped copper oxide superconductor. Nature Physics, 2011; DOI: 10.1038/nphys2006

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here