Tagged: Material Sciences Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 12:24 pm on August 15, 2016 Permalink | Reply
    Tags: , Craig Arnold, Material Sciences,   

    From Princeton- “Craig Arnold: Perspective on the allure and reach of materials science” 

    Princeton University
    Princeton University

    August 9, 2016
    John Sullivan

    Scholarly and administrative focus: Craig Arnold became director of the Princeton Institute for the Science and Technology of Materials (PRISM) Jan. 1 after serving as interim director since July 2015. The institute recently installed cutting-edge imaging equipment in the new Andlinger Center for Energy and the Environment building, including a microscope that is capable of imaging individual atoms and is one of only four of its kind in the world. In the control room of a new scanning electron microscope, Arnold recently answered questions about materials science and engineering at Princeton.

    Craig Arnold (pictured), professor of mechanical and aerospace engineering, became director of the Princeton Institute for the Science and Technology of Materials (PRISM) Jan. 1. Arnold recently discussed his passion for materials science and engineering, and his vision for those fields at Princeton. (Photo by David Kelly Crow)

    What is materials science?

    Materials science and engineering is the study of the stuff that makes up the world around us. Pretty much everything is composed of materials, whether it is the table that I am sitting at, or the car that you drive, or the computer that you use. What we do is we study these materials, how their atoms are arranged, how to change their properties and how to control their response to certain stimuli. Basically, the study of materials allows us to make new materials with exciting new properties or make the existing ones we have perform better.

    What is it about materials science that fascinates you?

    The interesting thing about materials science for me is that it brings together traditional disciplines in the natural sciences and engineering and tends to work at the interfaces among them. The joke that I always say is that the greatest thing about being a materials scientist is that it gives me a secret password that gets me into any club that I want. Whether it’s chemistry or physics, mechanical or electrical engineering, if you look around, you’re bound to find a materials scientist or engineer.

    You like to open your classes by mentioning your three favorite materials. What are they?

    [laughs] Silicon, steel and pre-stressed concrete. They all are things that require an incredible knowledge of materials science and each has reshaped civilizations. Steel really is the enabling technology that allowed us to become an agrarian society. What is particularly interesting about steel — compared to other forms of metalworking in the early historical period — is that to make steel you need to coordinate many different things. You can’t just dig a rock out of the ground and turn it into steel. You needed ore, and you needed trees, and you needed limestone. And you needed trade to get all of these things together. Not only the steel itself, but also the process of making it reshaped civilization. Of course, over the millennia people figured out how to make steel better and we are still doing that today; slight changes of the steel alloy make the difference between razor blades that stay sharp and ones that you have to throw away after few uses.

    Silicon, of course, has enabled the development of computers. Everyone thinks it was the transistor that made computers possible. And absolutely it was — the transistor made it possible. But what people don’t think about is that what enabled that transistor was the ability to create very pure materials. The semiconductors that you use in a computer, you have to be able to control the amount of impurities to incredibly fine levels. If you can’t do that, you can’t make a transistor that works. The materials scientists had to figure out how to make silicon really, really pure. That required many years of understanding: how to process materials, how to melt and form materials. Nowadays you can just call up a vendor and you buy a piece of silicon wafer to make a computer chip that has the exact amount of impurities you want in a 12-inch wafer with almost no flaws. This is a remarkable achievement of materials science and it is what allows us to make computers that are cheap.

    Pre-stressed concrete is a combination of materials that has allowed us to build the infrastructure of our society. Steel is very good in tension and concrete is very good in compression. Putting them together in the right way enables complex architecture, buildings, bridges and the like. You get the idea.

    I like that materials really do change society. They change the way we think about and interact with the world, how we use objects, and how we create things. That is why I like teaching it. I can take a class of students and starting from a minimal knowledge base, get them thinking about the world around them more generally and how they can use this science to engineer a better world or to understand the nature of things more fully.

    How did you get into the field?

    As a student, I always resonated with physics but it was a particular kind of physics. I always described myself as very interested in understanding the physics of objects that I could put on a table — I used to call it tabletop physics. In my second semester of a Ph.D. program in physics, I decided to take a course titled “Kinetics,” which is a part of materials science. I had almost no idea what it was about when I signed up, but I was in the class for two days and I said, “This is it; this is exactly what I want to do.” I went to the professor and asked, “Would you take on a new graduate student?” And, well, you can figure out what happened.

    What are some problems now — big science problems that people would think of as chemistry or physics or electronics problems — but at heart are really materials-science problems?

    I could answer that by saying everything. You give me an example and I will tell you how it is a materials-science problem. But let’s take ones that maybe are not as apparent. Let’s go big. You drove a car to come into work today, right? Ask yourself: What does that have to do with materials science? Well, let’s talk about electric vehicles. Can we make better batteries? That is not a pure chemistry problem because we know a lot about the basic chemistry of how a battery works already. Also, it’s not a pure electronics problem. The challenge now is in the materials — trying to figure out what materials are optimal, what materials are safe, what materials can meet the general requirements that we have in order to make better automobile batteries.

    Let’s take this idea of cars one step further — one way to make that car more fuel-efficient is to make it lighter. But if we make it lighter we don’t want to make it less safe. How do you deal with that tradeoff? That is a materials problem. If you go back 50 years, it was cast-iron engine blocks and steel everywhere else. Now you see more plastics, more fabrics, in the makeup of the body of the car, and more aluminum and lighter-weight materials in the engine. So being able to create lightweight materials that are structurally stable seems pretty basic, but it is a really important materials-science problem with major implications in a whole host of areas.

    In the relatively short term, what are a few goals for materials science and engineering at Princeton?

    My main goal is to establish Princeton as a leading place for materials science and engineering. I want us to be recognized as a top-ranked program. When people think about materials science, I want them to think about Princeton. Right now, the individual scholars who work at Princeton, and the work that they do, are well known in the field. But as an institute, we do not have the broad recognition that others have. I think we can make a more concerted effort to coordinate our message, highlight our expertise and build on our strengths so that we can attract the best students and researchers, and we can continue to be a leader in the field.

    Well, how do we do that? Firstly, the new facilities we are sitting in are an important step. Having the latest and most advanced toolset will enable researchers to perform cutting-edge research in their areas. But also, I think it is important to have a true graduate program in materials science and engineering. This will help us attract those top students who are going elsewhere because we don’t have a home for them. One of the great things about materials science is that the innovations we make enable other fields. It helps the electrical engineers make great strides in display technologies, the physicists develop new types of superconductors, or the biomedical researchers develop new ways to treat cancer. But we need to get beyond this idea of materials science being something that is behind the scenes. We need to bring it into the forefront.

    It’s like the bass player in a band.

    [laughs] I am OK with that. If you are going to be a successful band, you need to have a good bass player. But every now and again, it’s important to bring that bass player out front, and you hear the riff and you think, “That’s a really great bassist.” That is what we need to do. We want materials to be recognized, recognized for what we do on our own and also for what we do to help others be that much better. Ultimately, my feeling is that this is all one big university. And strength in any area is strength for everybody. We need materials science — it enables so many of the traditional disciplines. But it also is a deep and fascinating discipline in itself.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    Princeton University Campus

    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

    Princeton Shield

  • richardmitnick 5:45 am on July 26, 2016 Permalink | Reply
    Tags: , Material Sciences, Washington State U, Watching a material change its crystal structure in real time   

    From phys.org: “Researchers ‘watch’ crystal structure change in real time” 


    July 25, 2016
    Eric Sorensen

    Washington State University researchers have met the long-standing scientific challenge of watching a material change its crystal structure in real time.

    Configuration for the time-resolved, x-ray diffraction measurements in silicon subjected to impact loading. A PC projectile traveling at ∼5.1  km/s impacted the Si samples. Pulsed x rays (∼23.5  keV energy, ∼100  ps duration, 153.4 ns period) passed through the PC projectile, the silicon sample, and the PC window. Diffracted x rays from individual ∼100  ps x-ray pulses were detected on a framing area detector with a 75 mm diameter field of view. Photon Doppler velocimetry (PDV) was used to record the velocity history of the Si/PC interface

    X-ray diffraction results for shocked polycrystalline silicon. (a) Ambient cd phase Si diffraction image. (b)–(e) Time-resolved diffraction images with listed times relative to impact time. The images show the temporal transition from cd phase Si to sh phase Si as the shock wave travels through the material. (f) Measured and simulated (solid line) sh diffraction peaks 406 ns after impact. The broad inner ring labeled PC is from the polycarbonate window and projectile.

    While exposing a sample of silicon to intense pressure—due to the impact of a nearly 12,000 mph plastic projectile—they documented the transformation from its common cubic diamond structure to a simple hexagonal structure. At one point, they could see both structures as the shock wave traveled through the sample in less than half a millionth of a second.

    Their discovery is a dramatic proof of concept for a new way of discerning the makeups of various materials, from impacted meteors to body armor to iron in the center of the Earth.

    Until now, researchers have had to rely on computer simulations to follow the atomic-level changes of a structural transformation under pressure, said Yogendra Gupta, Regents professor and director of the WSU Institute of Shock Physics. The new method provides a way to actually measure the physical changes and to see if the simulations are valid.

    “For the first time, we can determine the structure,” Gupta said. “We’ve been assuming some things but we had never measured it.”

    Writing in Physical Review Letters, one of the leading physics journals, the researchers say their findings already suggest that several long-standing assumptions about the pathways of silicon’s transformation “need to be reexamined.”

    The discovery was made possible by a new facility, the Dynamic Compression Sector at the Advanced Photon Source located at the Argonne National Laboratory. Designed and developed by WSU, the sector is sponsored by the U.S. Department of Energy’s National Nuclear Security Administration, whose national security research mission includes fundamental dynamic compression science.The Advanced Photon Source synchrotron, funded by the Department of Energy’s Office of Science, provided high-brilliance x-ray beams that pass through the test material and create diffraction patterns that the researchers use to decode a crystal changing its structure in as little as five billionths of a second.

    “We’re making movies,” said Gupta. “We’re watching them in real time. We’re making nanosecond movies.”

    Stefan Turneaure, lead author of the Physical Review Letters paper and a senior scientist at the WSU Institute for Shock Physics, said the researchers exposed silicon to 19 gigapascals, nearly 200,000 times atmospheric pressure. The researchers accomplished this by firing a half-inch plastic projectile into a thin piece of silicon on a Lexan backing. While x-rays hit the sample in pulses, a detector captured images of the diffracted rays every 153.4 nanoseconds—the equivalent of a camera shutter speed of a few millionths of a second.

    “People haven’t used x-rays like this before,” said Turneaure. “Getting these multiple snapshots in a single impact experiment is new.”

    “What I’m very excited about is we are showing how the crystal lattice, how this diamond structure that silicon starts out with, is related to this ending structure, this hexagonal structure,” said Gupta. “We can see which crystal direction becomes which crystal direction. Stefan has done a great job. He’s mastered that. We were able to show how the two structures are linked in real time.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

  • richardmitnick 5:25 am on July 26, 2016 Permalink | Reply
    Tags: , Material Sciences, , Spider silk, Spiders spin unique phononic material   

    From Rice: “Spiders spin unique phononic material” 

    Rice U bloc

    Rice University

    July 25, 2016
    Mike Williams

    Researchers at Rice University, in Europe and in Singapore discover band gaps in spider silk

    Scientists at Rice University and in Europe and Singapore studied the microstructure of spider silk to see how it transmits phonons, quanta of sound that also have thermal properties. They suggested what they learned could be useful to create strong synthetic fibers with silk-like properties. Click on the image for a larger version. Illustration by Dirk Schneider

    New discoveries about spider silk could inspire novel materials to manipulate sound and heat in the same way semiconducting circuits manipulate electrons, according to scientists at Rice University, in Europe and in Singapore.

    A paper in Nature Materials looks at the microscopic structure of spider silk and reveals unique characteristics in the way it transmits phonons, quasiparticles of sound.

    The research shows for the first time that spider silk has a phonon band gap. That means it can block phonon waves in certain frequencies in the same way an electronic band gap – the basic property of semiconducting materials – allows some electrons to pass and stops others.

    The researchers wrote that their observation is the first discovery of a “hypersonic phononic band gap in a biological material.”

    How the spider uses this property remains to be understood, but there are clear implications for materials, according to materials scientist and Rice Engineering Dean Edwin Thomas, who co-authored the paper. He suggested that the crystalline microstructure of spider silk might be replicated in other polymers. That could enable tunable, dynamic metamaterials like phonon waveguides and novel sound or thermal insulation, since heat propagates through solids via phonons.

    “Phonons are mechanical waves,” Thomas said, “and if a material has regions of different elastic modulus and density, then the waves sense that and do what waves do: They scatter. The details of the scattering depend on the arrangement and mechanical couplings of the different regions within the material that they’re scattering from.”

    Spiders are adept at sending and reading vibrations in a web, using them to locate defects and to know when “food” comes calling. Accordingly, the silk has the ability to transmit a wide range of sounds that scientists think the spider can interpret in various ways. But the researchers found silk also has the ability to dampen some sound.

    “(Spider) silk has a lot of different, interesting microstructures, and our group found we could control the position of the band gap by changing the strain in the silk fiber,” Thomas said. “There’s a range of frequencies that are not allowed to propagate. If you broadcast sound at a particular frequency, it won’t go into the material.”

    In 2005, Thomas teamed with George Fytas, a materials scientist at the University of Crete and the Institute of Electronic Structure and Laser Foundation for Research and Technology-Hellas, Greece, on a project to define the properties of hypersonic phononic crystals. In that work, the researchers measured phonon propagation and detected band gaps in synthetic polymer crystals aligned at regular intervals.

    “Phononic crystals give you the ability to manipulate sound waves, and if you get sound small enough and at high enough frequencies, you’re talking about heat,” Thomas said. “Being able to make heat flow this way and not that way, or make it so it can’t flow at all, means you’re turning a material into a thermal insulator that wasn’t one before.”

    Fytas and Thomas decided to take a more detailed look at dragline silk, which spiders use to construct a web’s outer rim and spokes and as a lifeline. (A spider suspended in midair is clinging to a dragline.) Though silk has been studied for thousands of years, it has only recently been analyzed for its acoustic properties.

    Silk is a hierarchical structure comprised of a protein, which folds into sheets and forms crystals. These hard protein crystals are interconnected by softer, amorphous chains, Thomas said. Stretching or relaxing the interconnecting chains changes the silk’s acoustic properties by adjusting the mechanical coupling between the crystals.

    Fytas’ team at the Max Planck Institute for Polymer Research in Mainz, Germany, performed Brillouin light scattering experiments to test silk placed under varying degrees of stress. “That was George’s genius,” Thomas said. “With Brillouin scattering, you use light to create phonons as well as absorb them from the sample. BLS allows you to see how the phonons move around inside any object, depending on the temperature and the material’s microstructure.”

    They found that when silk was “super contracted,” the velocity of phonons decreased by 15 percent while the bandwidth of frequencies it could block increased by 31 percent. Conversely, when strained, the velocity increased by about 27 percent, while the bandwidth decreased by 33 percent. They first observed a band gap in native (uncontracted) silk at about 14.8 gigahertz, with a width of about 5.2 gigahertz.

    Just as interesting to the team was the “unique region of negative group velocity” they witnessed. At these conditions, even though phonon waves moved forward, the phase velocity moved backward, Thomas said. They suggested the effect may allow for the focusing of hypersonic phonons.

    “Right now, we don’t know how to do any of this in other macromolecular fiber materials,” Thomas said. “There’s been a fair amount of investigation on synthetic polymers like nylon, but nobody’s ever found a band gap.”

    Co-authors of the paper are Dirk Schneider of ebeam Technologies, Bern, Switzerland, and Nikolaos Gomopoulos of the Swiss Federal Institute of Technology in Lausanne, both formerly of the Max Planck Institute; Cheong Koh of DSO National Laboratories, Singapore; Periklis Papadopoulos of the Planck Institute and the University of Ioannina, Greece; and Friedrich Kremer of the Institute of Experimental Physics at the University of Leipzig, Germany. Fytas is a professor at the University of Crete and has an appointment at the Planck Institute. Thomas is the William and Stephanie Sick Dean of Rice’s George R. Brown School of Engineering, a professor of materials science and nanoengineering and of chemical and biomolecular engineering.

    The Aristeia Alliance of the Mediterranean Institute for Scientific Research, the European Research Council, the Sonderforschungsbereich/Transregio (Collaborative Research Center) and the Deutsch Forschungsgemeinschaft (German Research Foundation) supported the research.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Rice U campus

    In his 1912 inaugural address, Rice University president Edgar Odell Lovett set forth an ambitious vision for a great research university in Houston, Texas; one dedicated to excellence across the range of human endeavor. With this bold beginning in mind, and with Rice’s centennial approaching, it is time to ask again what we aspire to in a dynamic and shrinking world in which education and the production of knowledge will play an even greater role. What shall our vision be for Rice as we prepare for its second century, and how ought we to advance over the next decade?

    This was the fundamental question posed in the Call to Conversation, a document released to the Rice community in summer 2005. The Call to Conversation asked us to reexamine many aspects of our enterprise, from our fundamental mission and aspirations to the manner in which we define and achieve excellence. It identified the pressures of a constantly changing and increasingly competitive landscape; it asked us to assess honestly Rice’s comparative strengths and weaknesses; and it called on us to define strategic priorities for the future, an effort that will be a focus of the next phase of this process.

  • richardmitnick 12:15 pm on May 30, 2016 Permalink | Reply
    Tags: , , Material Sciences, Materials made to measure   

    From DESY: “Materials made to measure” 



    Functional building blocks of polymers, ceramics or metals are specifically assembled on the nano-, micro- or macro level in the three project areas A, B and C of the SFB 986. How this is accomplished depends on which – partly completely new – property profile the desired material shall have. Credit: TUHH

    Materials science continues to be funded as collaborative research centre

    The collaborative research centre SFB 986, entitled “Tailor-Made Multiscale Material Systems – M3” will be funded for another four years by the German Research Foundation (DFG, Deutsche Forschungsgemeinschaft). SFB 986 is a collaboration between the Hamburg University of Technology (TUHH), the Helmholtz Centre Geesthacht (HZG), the University of Hamburg (UHH) and DESY. Overall, a sum of 13 million euros has now been granted. The second phase of funding begins on 1 July 2016.

    Since 2012, some 80 scientist have been involved in 22 projects carrying out fundamental research into a new category of materials: so-called “tailor-made multiscale material systems”. The Hamburg collaborative project provides the ideal network for top-level research into material scientific issues: researchers can draw on expertise in the field of synthesising nanoparticles (UHH) and nanophotonics (TUHH), the mechanics of small systems (TUHH and HZG) as well as scattering methods, spectroscopy and tomography (DESY and HZG). The report by the DFG particularly emphasises this “living network”. “We are very pleased that our achievements so far are being recognised by the DFG in continuing to fund the SFB. The continuation of the SFB demonstrates that we are conducting top-level research in materials science on an international level,” says Gerold Schneider, spokesman for the SFB 986 and head of TUHH’s Institute of Advanced Ceramics.

    Over the next four years, novel material systems are to be developed, displaying even better mechanical, electrical or photonic properties. For example, the Hamburg scientists are a step closer to producing a material that would be warmly welcomed by medical engineers. A newly developed manufacturing technique allows them to produce a material based on nanoparticles and organic molecules that displays high elasticity and strength, while at the same time being extremely hard. This material could one day be used for dental fillings, for example, or to manufacture watch cases. The aim is to open the door to an entirely new range of properties and structures, and to develop these to maturity.

    The researchers at DESY’s NanoLab are in charge of a subproject, examining the interfaces of oxides and organic materials, which play a key role for the outstanding properties of these materials. In addition, they are working with TUHH on a subproject regarding polymers in nanoporous materials.

    The metropolitan region of Hamburg and international materials research are being boosted in the long term by the SFB 986. This is not only demonstrated by the scientific advances being made, but also by the new master’s course in “Materials Science” which has been introduced at TUHH. At the same time, the creation of the Centre for High-Performance Materials (ZHM) at TUHH as well as other investments in the scientific field of electron microscopy, are long-term measures for establishing and strengthening this successful alliance in the field of materials research in North Germany.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

  • richardmitnick 3:42 pm on May 16, 2016 Permalink | Reply
    Tags: , Material Sciences, Novel 'liquid wire' material inspired by spiders' capture silk,   

    From phys.org: “Scientists create novel ‘liquid wire’ material inspired by spiders’ capture silk” 


    May 16, 2016

    Hybrid material inspired from spiders. Credit: University of Oxford

    Why doesn’t a spider’s web sag in the wind or catapult flies back out like a trampoline? The answer, according to new research by an international team of scientists, lies in the physics behind a ‘hybrid’ material produced by spiders for their webs.

    Pulling on a sticky thread in a garden spider’s orb web and letting it snap back reveals that the thread never sags but always stays taut—even when stretched to many times its original length. This is because any loose thread is immediately spooled inside the tiny droplets of watery glue that coat and surround the core gossamer fibres of the web’s capture spiral.

    This phenomenon is described* in the journal PNAS by scientists from the University of Oxford, UK and the Université Pierre et Marie Curie, Paris, France.

    The researchers studied the details of this ‘liquid wire’ technique in spiders’ webs and used it to create composite fibres in the laboratory which, just like the spider’s capture silk, extend like a solid and compress like a liquid. These novel insights may lead to new bio-inspired technology.

    Professor Fritz Vollrath of the Oxford Silk Group in the Department of Zoology at Oxford University said: ‘The thousands of tiny droplets of glue that cover the capture spiral of the spider’s orb web do much more than make the silk sticky and catch the fly. Surprisingly, each drop packs enough punch in its watery skins to reel in loose bits of thread. And this winching behaviour is used to excellent effect to keep the threads tight at all times, as we can all observe and test in the webs in our gardens.’

    Access mp4 video here .

    The novel properties observed and analysed by the scientists rely on a subtle balance between fibre elasticity and droplet surface tension. Importantly, the team was also able to recreate this technique in the laboratory using oil droplets on a plastic filament. And this artificial system behaved just like the spider’s natural winch silk, with spools of filament reeling and unreeling inside the oil droplets as the thread extended and contracted.

    Dr Hervé Elettro, the first author and a doctoral researcher at Institut Jean Le Rond D’Alembert, Université Pierre et Marie Curie, Paris, said: ‘Spider silk has been known to be an extraordinary material for around 40 years, but it continues to amaze us. While the web is simply a high-tech trap from the spider’s point of view, its properties have a huge amount to offer the worlds of materials, engineering and medicine.

    ‘Our bio-inspired hybrid threads could be manufactured from virtually any components. These new insights could lead to a wide range of applications, such as microfabrication of complex structures, reversible micro-motors, or self-tensioned stretchable systems.’

    *Science paper: In-drop capillary spooling of spider capture thread inspires hybrid fibers with mixed solid–liquid mechanical properties, PNAS

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

  • richardmitnick 7:20 pm on May 9, 2016 Permalink | Reply
    Tags: , Argonne Lab, Material Sciences, Molecular engineering,   

    From U Chicago: “Molecular engineers discuss future of computing, healthcare and energy storage” 

    U Chicago bloc

    University of Chicago

    May 9, 2016
    Greg Borzo

    From left: Profs. Melody Swartz, Supratik Guha, David Awschalom and Paul Nealey discuss molecular engineering research being conducted at the University of Chicago and Argonne National Laboratory. Prof. Matthew Tirrell, director of IME and deputy laboratory director for science at Argonne, moderates the panel.

    Imagine unbreakable encryption, room-temperature superconductors, inexpensive molecular sensors, a cure for cancer. These are the challenges molecular engineers are taking on.

    These and other promising technologies were explored during “Future Science: Small Scale, Big Impact,” a presentation by scientists and engineers from the University of Chicago’s Institute for Molecular Engineering. The program, part of the UChicago Discovery Series, showcased research being conducted at the University and Argonne National Laboratory.

    Argonne Lab
    Argonne Lab Campus

    “We’re creating not only the first engineering program at the University of Chicago, but really the first of its kind in the world,” said moderator Matthew Tirrell, director of IME and deputy laboratory director for science at Argonne. “Engineering is about taking science into society and doing useful things for society,” he said.

    Trekkie technologies

    The program featured four speakers. David Awschalom, IME’s deputy director and an expert on spintronics and quantum information engineering, spoke about how some of the technology dreamed up long ago in Star Trek episodes, have actually become reality. The show’s universal translators and personal access data devices are today’s translation apps and tablet computers. Transporters, though, are still a work in progress, but quantum engineering is now enabling teleportation, a related technology operating at the level of single particles. Awschalom’s group is harnessing the way electrons spin to make highly sensitive sensors, build a framework for quantum simulators to design and test pharmaceuticals, develop tamper-proof encryption, bring medical imaging to the molecular level, and other cutting edge devices.

    “We’re building technologies with single atoms, and when you do that, the laws of quantum physics determine their behavior,” said Awschalom, the Liew Family Professor of Molecular Engineering. Quantum probes have extraordinary sensitivity and “may ultimately reveal the exact structure of molecules to determine their structural-functional relationships.

    “Students here are even taking quantum probes and placing them inside living cells,” he added. These probes “act as beacons, looking at the electromagnetic and thermal properties of the cells and sending that information out to the observer.

    “Quantum engineering is becoming a reality, and it will enable the discovery and design of new materials for practical applications,” Awschalom concluded. “What’s exciting is that we don’t know what ’s ahead in the future.”

    Nanoparticle vaccines that kill cancer

    Melody Schwartz, the William B. Ogden Professor of Molecular Engineering, noted that while engineers often take basic science and translate it into new technologies, engineers often do the reverse: use technology to understand basic science. For example, she and her collaborators are developing nanoparticle vaccines that can influence immune responses to tumors. These vaccines are designed to have surface molecules that look like a virus or bacteria, and Schwartz is researching whether these vaccines can activate immune system T-cells to kill tumors.

    “Cancer immunotherapy holds enormous promise,” she said. “One way to potentially facilitate cancer immunotherapy is to combine molecular engineering and nanotechnology with information about how the lymphatic system works.”

    Using protein engineering and nanoscale materials, this research is based on the fact the lymphatic system plays a central role in helping the immune system regulate immunity and make decisions about whether particular cells should be tolerated or killed.

    “The lymphatic system is a gold mine of information about tumors … such as the specific details of which proteins are being expressed and secreted,” she said. Targeting a lymph node that holds a metastatic tumor could manipulate the lymphatic system into using the information the system holds about that tumor to stimulate the immune system to fight the cancer. So far, Schwartz’s nanoparticle vaccines have been effective in mice when delivered to a lymph node to which cancer has metastasized. They have not been definitive when delivered to a lymph node on the other side of the body from where the cancer originated. Taken together, these results support the theory that the lymphatic system holds valuable information about a tumor, at least in mice.

    “Perhaps, instead of cutting out the lymph node of a patient (with cancer), we should target it and use (the information it holds),” Schwartz said.

    Cheaper sensors for agriculture and water utilization

    “Cyber physical systems that feature powerful yet inexpensive sensors made of nanoparticles will become ubiquitous,” said Supratik Guha, professor of molecular engineering and director of Argonne’s nanoscience and technology division. These systems will provide vast amounts of real-time data that will be used to measure and control pollution, electrical power consumption, water utilization, agricultural practices and other vital functions.

    “Nanotechnology has been around for about 25 years, but its ‘calling card’ will be what it does for sensors,” Guha said. “Nanoparticles are ideal for sensors because their properties are determined by the environment they’re in. They interact in different ways with light, magnetic fields, pressure” and other factors.

    Once these sensors become more powerful and less expensive, researchers will be able to “screw them in and out of cyber physical systems like light bulbs,” Guha said. “Once that happens, it could change the world.”

    For example, agriculture accounts for 70 percent of fresh water consumption. While working at IBM, Guha participated in an experiment at a vineyard that delivered water based on need rather than randomly. Using satellite data, each section was monitored for greenery—and then watered accordingly. “Over two harvests, yields and water efficiency went up by 10 to 20 percent,” Guha said.

    If agriculture could employ sensors to measure not only soil moisture but also dissolved nitrates, wind speed, plant disease, solar irradiance and other factors, tremendous savings could be realized, he concluded.

    “Magic materials” that can transform semi-conductor manufacturing

    When traditional photo lithographic techniques for manufacturing integrated circuits

    approached a limit to place an ever-increasing number of transistors on a single computer chip, other techniques, such as self-aligned double patterning, filled the gap, said Paul Nealey, the Brady W. Dougan professor of molecular engineering and senior scientist at Argonne.

    Nealey pioneered a relatively new technique called directed self-assembly, which involves making a chemical pattern on a chip and then depositing what he calls “magic materials” that respond to the chemical pattern and assemble themselves into the desired shape and structure.

    “These magic materials are not all that exotic,” Nealey said. They are co-polymers—two kinds of polymer chains connected at one end by a covalent bond. One of the materials is polystyrene (used to make plastic cups) and the other is PMMA (used to make Plexiglas). “These materials form structures at the molecular-length scale, which would be very difficult to achieve with traditional lithography.”

    Directed self-assembly is being commercialized in the context of semi-conductor manufacturing and applied to other areas, he added. For example, it is being used to make ion-conducting materials for membranes in fuel cells and batteries.

    Free and open to the public, the UChicago Discovery Series is designed to share the transformative research being conducted at the University. Attending this program were members of the Maroon Kids, a group organized by IME alumni and friends to promote interest in science and engineering topics among children in grades 6-12.

    One member asked, “How much do your fields interact with each other, and does solving a problem in one help solve a problem in another?”

    “Yes,” Schwartz answered. “New solutions will come from people who are interacting from completely different fields because they’re not stuck in one way of thinking about a solution. They’re coming at a problem from a fresh perspective and have multiple different perspectives.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

  • richardmitnick 10:33 am on April 5, 2016 Permalink | Reply
    Tags: , Material Sciences,   

    From Science Alert: “Scientists have just discovered a new state of matter – This is Big” 


    Science Alert

    5 APR 2016

    Genevieve Martin/Oak Ridge National Laboratory

    Researchers have just discovered evidence of a mysterious new state of matter in a real material. The state is known as ‘quantum spin liquid’ and it causes electrons – one of the fundamental, indivisible building blocks of matter – to break down into smaller quasiparticles.

    Scientists had first predicted the existence of this state of matter in certain magnetic materials 40 years ago, but despite multiple hints of its existence, they’ve never been able to detect evidence of it in nature. So it’s pretty exciting that they’ve now caught a glimpse of quantum spin liquid, and the bizarre fermions that accompany it, in a two-dimensional, graphene-like material.

    “This is a new quantum state of matter, which has been predicted but hasn’t been seen before,” said one of the researchers, Johannes Knolle, from the University of Cambridge in the UK.

    They were able to spot evidence of quantum spin liquid in the material by observing one of its most intriguing properties – electron fractionalisation – and the resulting Majorana fermions, which occur when electrons in a quantum spin state split apart. These Majorana fermions are exciting because they could be used as building blocks of quantum computers.

    To be clear, the electrons aren’t actually splitting down into smaller physical particles – which of course would be an even bigger deal (that would mean brand new particles!). What’s happening instead is the new state of matter is breaking electrons down into quasiparticles. These aren’t actually real particles, but are concepts used by physicists to explain and calculate the strange behaviour of particles.

    And the quantum spin liquid state is definitely making electrons act weirdly – in a typical magnetic material, electrons behave like tiny bar magnets. So when the material is cooled to a low enough temperature, these magnet-like electrons order themselves over long ranges, so that all the north magnetic poles point in the same direction.

    But in a material containing a quantum spin liquid state, even if a magnetic material is cooled to absolute zero, the electrons don’t align, but instead form an entangled soup caused by quantum fluctuations.

    “Until recently, we didn’t even know what the experimental fingerprints of a quantum spin liquid would look like,” said one of the researchers, Dmitry Kovrizhin. “One thing we’ve done in previous work is to ask, if I were performing experiments on a possible quantum spin liquid, what would I observe?”

    To figure out what was going on, the researchers worked alongside a team from Oak Ridge National Laboratory in Tennessee and used neutron scattering techniques to look for evidence of electron fractionalisation in alpha-ruthenium chloride – a material that’s structurally similar to graphene.


    This also allowed them to measure the signatures of Majorana fermions for the first time by illuminating the material with neutrons, and then observing the pattern of ripples that the neutrons produced when scattered from the sample.

    These patterns were exactly what they’d expect to see based on the main theoretical model of quantum spin liquid, confirming for the first time that they’d seen evidence of it happening in a material.

    “This is a new addition to a short list of known quantum states of matter,” said Knolle.

    “It’s an important step for our understanding of quantum matter,” added Kovrizhin. “It’s fun to have another new quantum state that we’ve never seen before – it presents us with new possibilities to try new things.”

    Some of those new things involve quantum computers – which would be exponentially faster than regular computers – so even though all of this sounds pretty theoretical, they could actually have some really exciting potential applications.

    The results have been published in Nature Materials.

    Proximate Kitaev quantum spin liquid behaviour in a honeycomb magnet

    The science team:
    A. Banerjee, C. A. Bridges, J.-Q. Yan, A. A. Aczel, L. Li, M. B. Stone, G. E. Granroth, M. D. Lumsden, Y. Yiu, J. Knolle, S. Bhattacharjee, D. L. Kovrizhin, R. Moessner, D. A. Tennant, D. G. Mandrus & S. E. Nagler


    Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
    A. Banerjee, A. A. Aczel, M. B. Stone, G. E. Granroth, M. D. Lumsden & S. E. Nagler
    Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
    C. A. Bridges
    Material Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
    J.-Q. Yan & D. G. Mandrus
    Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
    J.-Q. Yan & D. G. Mandrus
    Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA
    L. Li & Y. Yiu
    Neutron Data Analysis & Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
    G. E. Granroth
    Department of Physics, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
    J. Knolle & D. L. Kovrizhin
    Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
    S. Bhattacharjee & R. Moessner
    International Center for Theoretical Sciences, TIFR, Bangalore 560012, India
    S. Bhattacharjee
    Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA
    D. A. Tennant
    Bredesen Center, University of Tennessee, Knoxville, Tennessee 37966, USA
    S. E. Nagler


    S.E.N., A.B. and D.G.M. conceived the project and the experiment. C.A.B., A.B., L.L., J.-Q.Y., Y.Y. and D.G.M. made the sample. J.-Q.Y., L.L., A.B. and C.A.B. performed the bulk measurements, A.B., A.A.A., M.B.S., G.E.G., M.D.L. and S.E.N. performed INS measurements, A.B., S.E.N., C.A.B., M.D.L., M.B.S. and D.A.T. analysed the data. Further modelling and interpreting of the neutron scattering data was carried out by A.B., M.D.L., S.E.N., J.K., S.B., D.L.K. and R.M., where A.B., M.D.L., S.B. and S.E.N. performed SWT simulations, and J.K., S.B., D.L.K. and R.M. carried out QSL theory calculations. A.B. and S.E.N. prepared the first draft, and all authors contributed to writing the manuscript.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

  • richardmitnick 3:05 pm on February 2, 2016 Permalink | Reply
    Tags: "Shock/shear” platform, , , Material Sciences,   

    From LLNL: “NIF experiments shed light on turbulent mix” 

    Lawrence Livermore National Laboratory

    NIF Bloc

    LLNL NIF target on the National Ignition Facility (NIF) target positioner
    Cryogenics operator John Cagle mounts a target on the National Ignition Facility (NIF) target positioner for an experiment. An area backlighter disc is seen on-edge on the right of the assembly. The front of the target is covered with a gold shield with a diagnostic slit.

    Scientists from Los Alamos National Laboratory (LANL) are leading an experimental campaign on the National Ignition Facility (NIF) designed to further understand turbulent mix models used in both high energy density (HED) and inertial confinement fusion (ICF) experiments. NIF is the only facility with the energy and shot-to-shot reproducibility needed for the experiments.

    During shots using what’s known as the “shock/shear” platform, NIF fires 300 kilojoules of laser energy at each end of a target comprised of two half-hohlraums to produce shock waves from opposite ends of a foam-filled shock tube. These waves turn the foam into plasma and allow the shocks to travel and create a counter-propagating shear mixing effect across a metal foil.

    The target has evolved over time — different experiments have used titanium, copper, aluminum and roughened aluminum, and more materials are to come — but they all have one thing in common: each experiment enhances understanding of turbulent mix models in the HED regime. These models, developed and calibrated by LANL using hydrodynamic test data from the 1980s through the present, are now being examined through the lens of the shock/shear HED experiments to see how the data matches up to more extreme conditions.

    “We have created a system that reproduces instability features similar to those of traditional hydro experiments that have not previously been seen in HED experiments,” said LANL scientist Kirk Flippo, the lead experimental investigator. “This kind of experiment is rapidly evolving our understanding and we’ve discovered a lot of behaviors that we didn’t expect.”

    This enhanced understanding and refined data is vital for ICF. According to Flippo, it has become increasingly clear that ICF capsules experience some kind of mix as they are imploding.

    “Some of the outstanding issues in ICF are how does the capsule mix, how does this play into the degradation of the yield and how does it affect ignition,” he said. “It’s important for us to make sure that when we run a code to model an ICF implosion, we get all of the details correct. These experiments will help us quantify precisely how much of an effect this type of shear mixing has.”

    Shock/shear experiments initially were fielded on the OMEGA Laser at the University of Rochester’s Laboratory for Laser Energetics, but due to the limited volume that could be driven, the experiments experienced boundary effects. The LANL project manager, scientist John Kline, believed the platform was mature enough to be deployed on NIF and pushed hard for its implementation. Kline knew that by scaling the experiments up to NIF energies, the researchers would be able to take advantage of larger volumes to eliminate the edge effects and do the experiments they wanted to do.

    “We cannot do experiments in this way anywhere but at NIF,” Flippo said. “In the regimes that we are in at NIF, the experiment behaves much more like a traditional hydro experiment and scales like a hydro experiment would scale.”

    Data from the NIF experiments already has been used by the campaign’s principal investigator, LANL scientist Forrest Doss, to refine the way the model is implemented in the code — producing a direct, immediate impact. But the work isn’t complete just yet.

    “Now that this platform is available, and has been shown to produce really nice data, we can start modifying it by changing the shock velocities, changing the materials or foams and using different shocks,” Flippo said. “This platform has infinite variation and infinite complexity.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    LLNL Campus

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
    DOE Seal

  • richardmitnick 10:33 am on January 20, 2016 Permalink | Reply
    Tags: , Material Sciences, , Switchable material   

    From MIT: “Switchable material could enable new memory chips” 

    MIT News

    January 20, 2016
    David L. Chandler | MIT News Office

    Temp 1
    This diagram shows how an electrical voltage can be used to modify the oxygen concentration, and therefore the phase and structure, of strontium cobaltites. Pumping oxygen in and out transforms the material from the brownmillerite form (left) to the perovskite form (right).
    Courtesy of the researchers

    Small voltage can flip thin film between two crystal states — one metallic, one semiconducting.

    Two MIT researchers have developed a thin-film material whose phase and electrical properties can be switched between metallic and semiconducting simply by applying a small voltage. The material then stays in its new configuration until switched back by another voltage. The discovery could pave the way for a new kind of “nonvolatile” computer memory chip that retains information when the power is switched off, and for energy conversion and catalytic applications.

    The findings, reported in the journal Nano Letters in a paper by MIT materials science graduate student Qiyang Lu and associate professor Bilge Yildiz, involve a thin-film material called a strontium cobaltite, or SrCoOx.

    Usually, Yildiz says, the structural phase of a material is controlled by its composition, temperature, and pressure. “Here for the first time,” she says, “we demonstrate that electrical bias can induce a phase transition in the material. And in fact we achieved this by changing the oxygen content in SrCoOx.”

    “It has two different structures that depend on how many oxygen atoms per unit cell it contains, and these two structures have quite different properties,” Lu explains.

    One of these configurations of the molecular structure is called perovskite, and the other is called brownmillerite. When more oxygen is present, it forms the tightly-enclosed, cage-like crystal structure of perovskite, whereas a lower concentration of oxygen produces the more open structure of brownmillerite.

    The two forms have very different chemical, electrical, magnetic, and physical properties, and Lu and Yildiz found that the material can be flipped between the two forms with the application of a very tiny amount of voltage — just 30 millivolts (0.03 volts). And, once changed, the new configuration remains stable until it is flipped back by a second application of voltage.

    Strontium cobaltites are just one example of a class of materials known as transition metal oxides, which is considered promising for a variety of applications including electrodes in fuel cells, membranes that allow oxygen to pass through for gas separation, and electronic devices such as memristors — a form of nonvolatile, ultrafast, and energy-efficient memory device. The ability to trigger such a phase change through the use of just a tiny voltage could open up many uses for these materials, the researchers say.

    Previous work with strontium cobaltites relied on changes in the oxygen concentration in the surrounding gas atmosphere to control which of the two forms the material would take, but that is inherently a much slower and more difficult process to control, Lu says. “So our idea was, don’t change the atmosphere, just apply a voltage.”

    “Voltage modifies the effective oxygen pressure that the material faces,” Yildiz adds. To make that possible, the researchers deposited a very thin film of the material (the brownmillerite phase) onto a substrate, for which they used yttrium-stabilized zirconia.

    In that setup, applying a voltage drives oxygen atoms into the material. Applying the opposite voltage has the reverse effect. To observe and demonstrate that the material did indeed go through this phase transition when the voltage was applied, the team used a technique called in-situ X-ray diffraction at MIT’s Center for Materials Science and Engineering.

    The basic principle of switching this material between the two phases by altering the gas pressure and temperature in the environment was developed within the last year by scientists at Oak Ridge National Laboratory. “While interesting, this is not a practical means for controlling device properties in use,” says Yildiz. With their current work, the MIT researchers have enabled the control of the phase and electrical properties of this class of materials in a practical way, by applying an electrical charge.

    In addition to memory devices, the material could ultimately find applications in fuel cells and electrodes for lithium ion batteries, Lu says.

    “Our work has fundamental contributions by introducing electrical bias as a way to control the phase of an active material, and by laying the basic scientific groundwork for such novel energy and information processing devices,” Yildiz adds.

    In ongoing research, the team is working to better understand the electronic properties of the material in its different structures, and to extend this approach to other oxides of interest for memory and energy applications, in collaboration with MIT professor Harry Tuller.

    José Santiso, the nanomaterials growth division leader at the Catalan Institute of Nanoscience and Nanotechnology in Barcelona, Spain, who was not involved in this research, calls it “a very significant contribution” to the study of this interesting class of materials, and says “it paves the way for the application of these materials both in solid state electrochemical devices for the efficient conversion of energy or oxygen storage, as well as in possible applications in a new kind of memory devices.”

    The work was supported by the National Science Foundation.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    MIT Seal

    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    MIT Campus

  • richardmitnick 11:17 am on January 8, 2016 Permalink | Reply
    Tags: , Material Sciences, , Perovskites, Silicon and solar materials   

    From MIT Tech Review: “Promising New Solar Material Boosts Performance of Silicon” 

    MIT Technology Review
    M.I.T Technology Review

    January 7, 2016
    Mike Orcutt

    Silicon probably won’t be replaced as the dominant solar material anytime soon, but it might not be too long before it gets a partner from a promising class of materials called perovskites.

    A group led by Henry Snaith, a physicist at the University of Oxford and leading perovskite researcher, has demonstrated what it says is a viable pathway to a device that combines a conventional silicon cell with a perovskite cell to boost the efficiency of that silicon cell by several percentage points.

    Perovskites, which have captured the interest of solar researchers and energy policy experts because of their rapidly improving performance and low cost, are distinguished by a chemical structure that gives rise to unique electronic properties that make them attractive for solar technology (see “Could a New Solar Material Outperform Silicon?”). Snaith and his colleagues say the new composition they’ve developed overcomes a fundamental obstacle to designing a highly efficient device that combines the light-absorbing characteristics of silicon with those of a perovskite material.

    The researchers say the result suggests it should be possible to make a silicon-perovskite “tandem” device that is more than 25 percent efficient, higher than the performance of today’s commercially available silicon cells, which are about 17 to 20 percent efficient. The measurements they took were in a laboratory environment, but the approach could eventually be used to achieve significantly higher efficiencies than the best silicon panels on the market today.

    High-performance tandem devices made of semiconductors other than perovskite have already achieved efficiencies in the lab of over 40 percent, but they are extremely expensive because they require very technically complex manufacturing processes. Making perovskite solar cells is much simpler and cheaper, and the process could be integrated into existing silicon panel manufacturing lines by adding a few steps. Many experts believe the most realistic near-term commercial application of perovskites will be a tandem device with silicon.

    Several groups have demonstrated working tandem devices made of a silicon cell and a perovskite cell, but the efficiencies have been limited because the range of the solar spectrum the perovskite absorbed did not fully complement the range that silicon absorbs. Attempts to tweak the range of light the perovskite absorbs led to instabilities within the material’s structure that compromised performance. Snaith and his colleagues came up with a method, which relies on substituting certain ions in the material with cesium ions, to achieve the desired photovoltaic properties while maintaining the material’s structural stability.

    The researchers have only demonstrated the new composition at a small scale, and a lot of work would be needed before we might see it in commercially available panels. But a company Snaith cofounded, Oxford PV, is also focused on developing silicon-perovskite tandem devices.

    Chris Case, chief technology officer of Oxford PV, says results like this reflect how quickly researchers are addressing the inherent challenges to making reliable, high-performing tandem cells. Case won’t reveal the specifics of his company’s technology, but says Oxford PV is close to demonstrating full-size devices that are 23 percent efficient and could hit 25 percent shortly thereafter. Case says it’s not unrealistic to think 28 or even 30 percent efficiency is possible within just a few years.

    Perovskite-based technologies still face challenges due to the material’s sensitivity to moisture and air, and questions remain about whether perovskite cells can be made durable enough to survive the long lifetimes required of power systems. Still, Case says Oxford PV is on track to deliver a commercial product—aimed at silicon panel manufacturers who want to “upgrade” the efficiency of their products—in 2017.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The mission of MIT Technology Review is to equip its audiences with the intelligence to understand a world shaped by technology.

Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc

Get every new post delivered to your Inbox.

Join 597 other followers

%d bloggers like this: