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Tag: Materials Science

  • Making materials more durable through science

    Making materials more durable through science

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    BYLINE: Kim Vallez Quintana

    Newswise — ALBUQUERQUE, N.M. — A team at Sandia National Laboratories developed a molecule that helps change the way some materials react to temperature fluctuations, which makes them more durable. It’s an application that could be used in everything from plastic phone cases to missiles.

    Polymers, which include various forms of plastics, are made up of many smaller molecules, bonded together. This bond makes them especially strong and an ideal product to be used to protect delicate components in a wide variety of items. But with time, use and exposure to different environments, all materials begin to deteriorate.

    Hot to cold, cold to hot, the big problem

    One of the biggest factors in materials deterioration is repeated exposure from hot to cold temperatures and back. Most materials expand when heated and contract when cooled, but each material has its own rate of change. Polymers, for example, expand and contract the most, while metals and ceramics contract the least.

    Erica Redline, a materials scientist who leads the team, said most items are made up of more than one kind of material.

    “Take for example, your phone, which has a plastic housing, coupled to a glass screen, and inside that, the metals and ceramics that make up the circuitry,” Redline said. “These materials are all screwed, glued or somehow bonded together and will start expanding and contracting at different rates, putting stresses on one another which can cause them to crack or warp over time.”

    Redline said she kept hearing the same complaint from Sandia’s many customers.

    “They’re always talking about thermal expansion mismatch problems and how their existing systems are hard to work with because of all the filler they need to add to compensate,” Redline said.

    With that, Redline’s idea was born.

    “I thought, what if I conjured up a perfect material, what would that look like,” Redline said.

    Redline thinks she’s done it, with the help of her team Chad Staiger, Jason Dugger, Eric Nagel, Koushik Ghosh, Jeff Foster, Kenneth Lyons, Alana Yoon and academic alliance collaborators Professor Zachariah Page and graduate student Meghan Kiker.

    The molecule in action

    The team modified a molecule so that it can easily be incorporated into a polymer to change its properties.

    “This really is a unique molecule that when you heat it up, instead of it expanding, it actually contracts by undergoing a change in its shape,” Redline said.

    “When it’s added to a polymer, it causes that polymer to contract less, hitting expansion and contraction values similar to metals. To have a molecule that behaves like metal is pretty remarkable.”

    Endless possibilities

    This molecule could be used in endless ways. Polymers are used as protective coatings in electronics, communications systems, solar panels, automotive components, printed circuit boards, aerospace applications, defense systems, flooring and more.

    “The molecule not only solves current issues but significantly opens up design space for more innovations in the future,” said Jason Dugger, a Sandia chemical engineer who has been looking at potential applications, especially in defense systems.

    Another key to this invention is that it can be incorporated into different parts of a polymer at different percentages, in 3D printing.

    “You could print a structure with certain thermal behaviors in one area, and other thermal behaviors in another to match the materials in different parts of the item,” Dugger said.

    Another benefit is helping reduce the weight of materials by eliminating heavy fillers.

    “It would enable us to do things much lighter to save mass,” Dugger said. “That is especially important when launching a satellite, for example. Every gram we can save is huge.”

    Redline said she has also been approached by an epoxy formulator who believes this molecule could be incorporated into adhesives.

    The next step

    The team has only created this molecule in small quantities, but they are working to find a way to scale up production so that other Sandia researchers can test the molecule to fit mission needs.

    Chad Staiger, an organic chemist at Sandia, makes the molecule. He said it takes him about 10 days to make between 7-10 grams.

    “It’s unfortunately a long synthesis for this molecule,” Staiger said. “More steps equal more time and more money. You usually see five- to six-step syntheses in higher value materials such as pharmaceuticals. In polymers, the cheaper the better for wide scale adoption.”

    The team is working to reduce the steps using $100,000 in funding through Sandia’s technology maturation program, which helps ready products for the marketplace.

    “My role is to see if there is an easier way to make it at a commercial level,” said postdoc Eric Nagel. “There is nothing like it out there. I am really excited at the possibilities of what this technology can do and the applications that could be associated with this.”

    “It’s pretty phenomenal and pretty wide open,” Staiger said.

    Dugger agreed: “It really is a sky’s the limit kind of thing.”

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    Sandia National Laboratories

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  • Making Big Leaps in Understanding Nanoscale Gaps

    Making Big Leaps in Understanding Nanoscale Gaps

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    Newswise — Creating novel materials by combining layers with unique, beneficial properties seems like a fairly intuitive process—stack up the materials and stack up the benefits. This isn’t always the case, however. Not every material will allow energy to travel through it the same way, making the benefits of one material come at the cost of another.

    Using cutting-edge tools, scientists at the Center for Functional Nanomaterials (CFN), a U.S. Department of Energy (DOE) User Facility at Brookhaven National Laboratory, and the Institute of Experimental Physics at the University of Warsaw have created a new layered structure with 2D material that exhibits a unique transfer of energy and charge. Understanding its material properties may lead to advancements in technologies like solar cells and other optoelectronic devices. The results were published in the American Chemical Society’s Nano Letters.

    2D Materials – Tiny, but Mighty

    Transition metal dichalcogenides (TMDs) are a class of materials structured like sandwiches with atomically thin layers. The meat of a TMD is a transition metal, which can form chemical bonds with electrons on their outermost orbit or shell, like most elements, as well as the next shell. That metal is sandwiched between two layers of chalcogens, a category of elements that contains oxygen, sulfur, and selenium. Chalcogens all have six electrons in their outermost shell, which makes their chemical behavior similar. Each of these material layers is only one atom thick—one-millionth the thickness of a strand of human hair—leading them to be referred to as two-dimensional (2D) materials.

    “At the atomic level, you get to see these unique and tunable electronic properties,” said Abdullah Al-Mahboob, a Brookhaven staff scientist in the CFN Interface Science and Catalysis group. “TMDs are like a playground of physics. We’re moving energy around from one material to the other at an atomic level.”

    Some new properties start to emerge from materials at this scale. Graphene, for example, is the 2D version of graphite, the material that most pencils are made of. In a Nobel Prize-winning experiment, scientists used a piece of adhesive tape to pull flakes off of graphite to study a layer of graphene. The researchers found the graphene to be incredibly strong at the atomic level—200 times stronger than steel relative to its weight! In addition, graphene is a great thermal and electrical conductor and has a unique light absorption spectrum. This unlocked the door to studying the 2D forms of other materials and their properties.

    2D materials are interesting on their own, but when combined, surprising things start to happen. Each material has its own superpower—protecting materials from the environment, controlling the transfer of energy, absorbing light in different frequencies—and when scientists start to stack them together, they create what is known as a heterostructure. These heterostructures are capable of some extraordinary things and could one day be integrated into future technologies, like smaller electronic components and more advanced light detectors.

    QPress—A First-of-its-Kind Experimental Tool

    While the exploration of these materials may have started with something as simple as a piece of adhesive tape, the tools used to extract, isolate, catalog, and build 2D materials have become quite advanced. At CFN, an entire system has been dedicated to the study of these heterostructures and the techniques used to create them—the Quantum Material Press (QPress).

    “It’s hard to compare the QPress to anything,” said Suji Park, a Brookhaven staff scientist specializing in electronic materials. “It builds a structure layer by layer, like a 3D printer, but 2D heterostructures are built by an entirely different approach. The QPress creates material layers that are an atom or two thick, analyzes them, catalogs them, and finally assembles them. Robotics is used to systematically fabricate these ultrathin layers to create novel heterostructures.”

    The QPress has three custom built modules—the exfoliator, cataloger, and stacker. To create 2D layers, scientists use the exfoliator. Similar to the manual adhesive tape technique, the exfoliator has a mechanized roller assembly that exfoliates thin layers from larger source crystals with controls that provide the kind of precision that can’t be achieved by hand. Once collected and distributed, the source crystals are pressed onto a silicone oxide wafer and peeled off. They are then passed along to the cataloger, an automated microscope combing several optical characterization techniques. The cataloger uses machine learning (ML) to identify flakes of interest that are then cataloged into a database. Currently, ML is trained with only graphene data, but researchers will keep adding different kinds of 2D materials. Scientists can use this database to find the material flakes they need for their research.

    When the necessary materials are available, scientists can use the stacker to fabricate heterostructures from them. Using high-precision robotics, they take the sample flakes and arrange them in the order needed, at any necessary angle, and transfer substrates to create the final heterostructure, which can be stored long-term in a sample library for later use. The climate is controlled to ensure the quality of the samples and the fabrication process from exfoliation to building heterostructures is conducted in an inert gas environment in a glovebox. The exfoliated flakes and the stacked samples are stored in vacuum, in the sample libraries of the QPress cluster. Additionally, electron beam evaporation, annealing, and oxygen plasma tools are available in the vacuum side of the cluster. Robotics are used to pass samples from one area of the QPress to the next. Once these novel heterostructures are fabricated though, what do they actually do and how do they do it?

    After the team at CFN fabricated these fascinating new materials with the QPress, they integrated the materials with a suite of advanced microscopy and spectroscopy tools that enabled them to explore optoelectronic properties without exposing the samples to air, which would degrade material structures. Some of the delicate, exotic quantum properties on 2D materials need ultra-low cryo-temperatures to be detected, down to just a few kelvins. Otherwise, they get perturbed by the slightest amount of heat or any chemicals present in the air.

    Al-Mahboob’s work is funded by the DOE Quantum Materials: Integrated Multimodal Characterization and Processing (QM-IMCP) project that CFN has started to build. This platform will include advanced microscopes, x-ray spectrometers, and ultrafast lasers that are able to investigate the quantum world at cryo-temperatures.

    Building Better Structures

    Using the advanced capabilities of these resources, the team was able to get a more detailed picture of how long-distance energy transfer works in TMDs.

    Energy wants to move across materials, the way a person wants to climb a ladder, but it needs a place to hold on to. Bandgaps can be thought of as the space between the rungs of a ladder. The larger the gap, the harder and slower it is to climb. If the gap is too large, it might not even be possible to finish moving up. Using materials that already have great conducting properties, this specialized team of scientists was able to stack them in a way that leveraged their structure to create pathways that transfer the charge more efficiently.

    One of the TMDs the team created was molybdenum disulfide (MoS2), which was shown in previous studies to have strong photoluminescence. Photoluminescence is the phenomenon that makes certain materials glow in the dark after they are exposed to light. When a material absorbs light with more energy than that energy bandgap, it can emit light with photon energy equal to the bandgap energy. If a second material with an equal or lower energy bandgap gets closer to the first, as close as a sub-nanometer to few nanometers, energy can transfer nonradiatively from the first material to the second. The second material can then emit light with photon energy equal to its energy bandgap.

    With an insulating interlayer made of hexagonal boron nitride (hBN), which prevents electronic conductivity, scientists observed an unusual kind of long-distance energy transfer between this TMD and one made of tungsten diselenide (WSe2), which conducts electricity very efficiently. The energy transfer process occurred from the lower-to-higher bandgap materials, which is not typical in TMD heterostructures, where the transfer usually occurs from the higher-to-lower bandgap 2D materials. The thickness of the interlayer played a big role, but also appeared to defy expectations. “We were surprised by the behavior of this material,” said Al-Mahboob. “The interaction between the two layers increases along with the increase in distance up to a certain degree, and then it begins to decrease. Variables like spacing, temperature, and angle played an important role.”

    By gaining a better understanding of how these materials absorb and emit energy at this scale, scientists can apply these properties to new types of technologies and improve current ones. These could include solar cells that absorb light more effectively and hold a better charge, photosensors with higher accuracy, and electronic components that can be scaled down to even smaller sizes for more compact devices.

    This study was supported by the DOE Office of Science.

    Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.

    Follow @BrookhavenLab on social media. Find us on Instagram, LinkedIn, Twitter, and Facebook.

     

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    Brookhaven National Laboratory

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  • Texas Tech Physicist Lands NSF Grant

    Texas Tech Physicist Lands NSF Grant

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    BYLINE: Doug Hensley

    Newswise — Myoung-Hwan Kim, an assistant professor in the Department of Physics and Astronomy at Texas Tech University, has been awarded a National Science Foundation grant in the field of materials research (DMR) related to quantum information science (QIS).

    An emerging field of research, QIS involves studying the transmission of information through quantum mechanics principles. Kim’s research will examine the influence of magnetism and topology on quantum particles delivering information. Kin’s award is one of two Texas Tech recently received from the NSF for QIS research. The other was awarded to Lu Wei, an assistant professor in the Department of Computer Sciences.

    “When a magnetic field is applied, the particles’ spin aligns with the field’s direction. However, when both an electric and a magnetic field are present, charged particles move in a direction parallel to the electric field but perpendicular to the magnetic field. As a result, the spin direction of the particles remains perpendicular to their direction of motion,” Kim said.

    “But some quantum particles in a solid react differently. The spin direction determines where the particle moves so the quantum particles only move when both electric and magnetic fields are aligned in the same direction. This we call a quantum anomaly that could be the foundation for a new qubit.”

    The NSF award acknowledges the vital work Texas Tech researchers are doing in this area, said Joseph A. Heppert, vice president for research & innovation.

    “Congratulations to Dr. Kim for receiving this new award from the National Science Foundation,” he said. “Quantum science is a high-priority research area for the nation. Innovations in quantum technology are expected to lead to revolutions in many areas of technology, including computer science and telecommunications. Texas Tech is extremely proud of Dr. Kim for his contributions to this critical and rapidly developing research field.”

    Kim’s work is in response to one of the challenges facing current quantum computers, a concept known as quantum decoherence, which occurs when information is lost during a computational process or information transport. Current quantum computers attempt to resolve decoherence by keeping qubits (quantum bits) from their surroundings, but as the qubit numbers increase, this becomes more difficult.

    As a result, scientists are seeking “topological qubits” that protect against decoherence because of their unique makeup, which could ultimately resolve the information loss issue. Two promising avenues of research have developed to try and address the problem.

    The first involves particles known as Majorana fermions, which are their own antiparticles, but this possibility has not gained significant traction yet. The second, research path involves Weyl fermions, which have shown more promise and where Kim is focusing his work during the life of the two-year NSF grant.

    “I am very pleased that two early-career faculty members at Texas Tech have successfully obtained NSF grants in the area of quantum information science research,” said Sung-Won Lee, department chair. “QIS is a new cross-disciplinary field of research, and a variety of research in this area has taken place on the Texas Tech campus since 2019.”

    The NSF grant will support Kim’s research, which aims to gain a fundamental understanding of quantum anomalies as well as their relationship with topology and the magnetic environment surrounding Weyl fermions. Kim’s lab at Texas Tech includes an advanced magneto-optical setup that was developed on campus. The hope is Kim’s work will provide new insights into controlling the functionality of Weyl fermions through optical, electrical and magnetic means.

    “The quantum anomalies can be controlled,” Kim said. “I want to study how the topology and the magnetic field influence the quantum particles’ motion and see how we control the quantum information flow using polarized light.”

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    Texas Tech University

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  • New platform empowers high-entropy alloy electrocatalysis study

    New platform empowers high-entropy alloy electrocatalysis study

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    Newswise — Introduced in 2004, high-entropy alloys (HEAs) are alloys composed of multiple principal elements in nearly equiatomic proportions. Their unique chemical composition results in a high degree of chemical disorder, i.e. entropy, and produces remarkable properties such as high strength, ductility, and strong wear-and-tear resistance even at high temperatures. Scientists have dedicated a significant amount of attention to developing novel HEAs to help improve the performance of various electrocatalyst materials.

    Because they are made up of differing constituent elements, HEAs’ atomic-level surface designs can be complex. But unravelling this complexity is crucial, since the surface properties of materials often dictate their catalytic activity. Hence why researchers are seeking to understand the correlation between the atomic arrangement and the catalytic properties exhibited by HEAs.

    Now, a collaborative research team has created a new experimental platform that enables the control of the atomic-level structure of HEAs’ surfaces and the ability to test their catalytic properties. Their breakthrough was reported in the journal Nature Communications on July 26, 2023.

    “In our study we made thin layers of an alloy called a Cantor alloy, which contains a mix of elements (Cr-Mn-Fe-Co-Ni), on platinum (Pt) substrates,” explains Toshimasa Wadayama, co-author of the paper and a professor at Tohoku University’s Graduate School of Environmental Studies. “This produced a model surface for studying a specific reaction called the oxygen reduction reaction (ORR).”

    Using advanced imaging techniques, the group examined the atomic-level structure of the Pt-HEAs’ surfaces and studied their ORR properties. They discovered that the Pt-HEAs’ surfaces performed better in ORR compared to surfaces made of a platinum-cobalt alloy. This indicates that the atomic arrangement and distribution of elements near the surface, which creates a ‘pseudo-core-shell-like structure,’ contributes to the excellent catalytic properties of Pt-HEAs.

    Wadayama and his group stress the wide applicability of their findings, both for any constituent elements and to other nanomaterials.

    “Our newly constructed experimental study platform provides us with a powerful tool to elucidate the detailed relationship between multi-component alloy surface microstructures and their catalytic properties. It is valid for clarifying the precise correlations among the atomic-level, surface microstructure and electrocatalytic properties of HEAs of any constituent elements and ratios and, thus, would provide reliable training datasets for materials informatics. The platform is applicable not only to electrocatalysis but also in various fields of functional nanomaterials.”

    Looking ahead, the group hopes to expand this platform into practical electrocatalysis by using Pt-HEA-nanoparticles that seek to increase electrochemical surface areas.

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    Tohoku University

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  • A Groundbreaking Addition to the Chemist’s Arsenal of Tools

    A Groundbreaking Addition to the Chemist’s Arsenal of Tools

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    Newswise — Microscopic materials made of clay designed by researchers at the University of Missouri could be key to the future of synthetic materials chemistry. By enabling scientists to produce chemical layers tailor-made to deliver specific tasks based on the goals of the individual researcher, these materials called nanoclays can be used in a wide variety of applications, including the medical field or environmental science. 

    A fundamental part of the material is its electrically charged surface, said Gary Baker, co-principal investigator on the project and an associate professor in the Department of Chemistry.      

    “Imagine a koosh ball where the thousands of rubber strands radiating from the ball’s core each sport an electrically charged bead on the end,” Baker said. “It’s analogous to a magnet — positively charged things will stick to negatively charged things. For instance, positively charged nanoclays could attract a group of harmful fluorinated chemicals known as PFAS, or “forever chemicals” which are negatively charged. Or, by making the nanoclay negatively charged, it can stick to things such as heavy metal ions like cadmium, which are positively charged, and help remove them from a contaminated body of water.”

    In addition to the electrical charge, each nanoclay can be customized with different chemical components, like mixing and matching different parts. This makes them usable in the design of diagnostic sensors for biomedical imaging or explosive and ordnance detection. 

    “Essentially, these nanoclays represent chemical building blocks designed with specific functions which are assembled into extremely thin, two-dimensional microscopic sheets — thinner than a strand of human DNA and 100,000 times thinner than a sheet of paper,” Baker said. “We can customize the function and shape of the chemical components presented at the surface of the nanoclay to make whatever we want to build. We’ve just exposed the tip of the iceberg for what these materials can do.”  

    Two-dimensional materials are highly sought after because they can superficially coat the outside of a bulky object in a thin, conformal layer and introduce completely different surface properties than the object underneath.

    “By mixing and matching a few things like different ions or gold nanoparticles, we can quickly design chemistry that’s never existed before, and the more we tailor it, the more it opens a wider range of applications,” Baker said.   

    “Surface programmable polycationic nanoclay supports yielding 100,000 per hour turnover frequencies for a nanocatalyzed canonical nitroarene reduction,” was published in ACS Applied Engineering Materials, a journal of the American Chemical Society. Co-authors are Nathaniel Larm at the United States Naval Academy, Durgesh Wagle at Florida Gulf Coast University and Piyuni Ishtaweera and Angira Roy at MU. The content is solely the responsibility of the authors and does not represent the official views of the U.S. government. 

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    University of Missouri, Columbia

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  • Spallation Neutron Source accelerator achieves world-record 1.7-megawatt power level to enable more scientific discoveries

    Spallation Neutron Source accelerator achieves world-record 1.7-megawatt power level to enable more scientific discoveries

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    Newswise — The Spallation Neutron Source at the Department of Energy’s Oak Ridge National Laboratory set a world record when its particle accelerator beam operating power reached 1.7 megawatts, substantially improving on the facility’s original design capability.

    The accelerator’s higher power provides more neutrons for researchers who use the facility to study and improve a wide range of materials for more efficient solar panels, longer–lasting batteries and stronger, lighter materials for transportation. The achievement marks a new operational milestone for neutron scattering in the United States and opens the door to tackling more difficult questions and problems in materials science research.

    “This increase in beam power represents another milestone in the Proton Power Upgrade project, an essential component in enabling new science at the SNS, including insights into advanced materials for clean energy applications,” said interim ORNL Director Jeff Smith. “I commend our staff for their efforts in accomplishing this new record.”

    Since construction was completed in 2006, the SNS has been a world-leading DOE Office of Science user facility that provides powerful advanced scientific capabilities for thousands of researchers from around the world to study energy phenomena and materials down to the atomic scale.

    The facility produces neutrons by accelerating protons down a 300-meter-long linear accelerator, around an accumulator ring and into a liquid mercury target. Upon impact, a “spall” of neutrons is routed to surrounding research instruments, which enables scientists to study the atomic structure and behavior of various materials. Neutrons scatter off atoms within the material and are captured by high-speed detectors, revealing fundamental information for research teams to analyze.

    A megawatt is a unit of measure of the beam power of a particle accelerator. The SNS’ 1.7-megawatt power level was reached after the recent installation of additional accelerating systems, part of the ongoing Proton Power Upgrade project at the accelerator.

    ORNL’s Proton Power Upgrade will continue to push the particle accelerator’s beam power up to 2.8 megawatts. This will increase the number of neutrons available for experiments at the existing First Target Station to enable new discoveries and power the planned Second Target Station, a complementary third neutron source at ORNL. STS will address emerging science challenges through experiments not currently feasible nor routine, with the ability to study smaller or less-concentrated samples or those under more extreme environmental conditions.

    Besides SNS, ORNL is home to the High Flux Isotope Reactor. Completed in 1965 and operating at 85 megawatts, HFIR’s steady-state neutron beam is the strongest reactor-based neutron source in the United States.

    The SNS and HFIR facilities produce neutron beams that help spur innovations that lead to improvements in daily life, such as more powerful computers, cleaner air, more effective drugs and longer-lasting batteries.

    SNS and HFIR are DOE Office of Science user facilities.

    UT-Battelle manages ORNL for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

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    Oak Ridge National Laboratory

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  • ‘Stunning’ discovery: Metals can heal themselves

    ‘Stunning’ discovery: Metals can heal themselves

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    Newswise — ALBUQUERQUE, N.M. — Scientists for the first time have witnessed pieces of metal crack, then fuse back together without any human intervention, overturning fundamental scientific theories in the process. If the newly discovered phenomenon can be harnessed, it could usher in an engineering revolution — one in which self-healing engines, bridges and airplanes could reverse damage caused by wear and tear, making them safer and longer-lasting.

    The research team from Sandia National Laboratories and Texas A&M University described their findings today in the journal Nature.

    “This was absolutely stunning to watch first-hand,” said Sandia materials scientist Brad Boyce.

    “What we have confirmed is that metals have their own intrinsic, natural ability to heal themselves, at least in the case of fatigue damage at the nanoscale,” Boyce said.

    Fatigue damage is one way machines wear out and eventually break. Repeated stress or motion causes microscopic cracks to form. Over time, these cracks grow and spread until — snap! The whole device breaks, or in the scientific lingo, it fails.

    The fissure Boyce and his team saw disappear was one of these tiny but consequential fractures — measured in nanometers.

    “From solder joints in our electronic devices to our vehicle’s engines to the bridges that we drive over, these structures often fail unpredictably due to cyclic loading that leads to crack initiation and eventual fracture,” Boyce said. “When they do fail, we have to contend with replacement costs, lost time and, in some cases, even injuries or loss of life. The economic impact of these failures is measured in hundreds of billions of dollars every year for the U.S.”

    Although scientists have created some self-healing materials, mostly plastics, the notion of a self-healing metal has largely been the domain of science fiction.

    “Cracks in metals were only ever expected to get bigger, not smaller. Even some of the basic equations we use to describe crack growth preclude the possibility of such healing processes,” Boyce said.

    Unexpected discovery confirmed by theory’s originator

    In 2013, Michael Demkowicz — then an assistant professor at the Massachusetts Institute of Technology’s department of materials science and engineering, now a full professor at Texas A&M — began chipping away at conventional materials theory. He published a new theory, based on findings in computer simulations, that under certain conditions metal should be able to weld shut cracks formed by wear and tear.

    The discovery that his theory was true came inadvertently at the Center for Integrated Nanotechnologies, a Department of Energy user facility jointly operated by Sandia and Los Alamos national laboratories.

    “We certainly weren’t looking for it,” Boyce said.

    Khalid Hattar, now an associate professor at the University of Tennessee, Knoxville, and Chris Barr, who now works for the Department of Energy’s Office of Nuclear Energy, were running the experiment at Sandia when the discovery was made. They only meant to evaluate how cracks formed and spread through a nanoscale piece of platinum using a specialized electron microscope technique they had developed to repeatedly pull on the ends of the metal 200 times per second.

    Surprisingly, about 40 minutes into the experiment, the damage reversed course. One end of the crack fused back together as if it was retracing its steps, leaving no trace of the former injury. Over time, the crack regrew along a different direction.

    Hattar called it an “unprecedented insight.”

    Boyce, who was aware of the theory, shared his findings with Demkowicz.

    “I was very glad to hear it, of course,” Demkowicz said. The professor then recreated the experiment on a computer model, substantiating that the phenomenon witnessed at Sandia was the same one he had theorized years earlier.

    Their work was supported by the Department of Energy’s Office of Science, Basic Energy Sciences; the National Nuclear Security Administration and the National Science Foundation.

    A lot remains unknown about the self-healing process, including whether it will become a practical tool in a manufacturing setting.

    “The extent to which these findings are generalizable will likely become a subject of extensive research,” Boyce said. “We show this happening in nanocrystalline metals in vacuum. But we don’t know if this can also be induced in conventional metals in air.”

    Yet for all the unknowns, the discovery remains a leap forward at the frontier of materials science.

    “My hope is that this finding will encourage materials researchers to consider that, under the right circumstances, materials can do things we never expected,” Demkowicz said.

    Sandia National Laboratories is a multimission laboratory operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration. Sandia Labs has major research and development responsibilities in nuclear deterrence, global security, defense, energy technologies and economic competitiveness, with main facilities in Albuquerque, New Mexico, and Livermore, California.

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    Sandia National Laboratories

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  • Developing new materials to accelerate the arrival of ‘air taxis’

    Developing new materials to accelerate the arrival of ‘air taxis’

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    Newswise — In order for future mobility, such as urban air mobility (UAM), to become a reality, it must be fuel efficient and reduce carbon emissions, which requires the development of new materials with excellent physical properties and recyclability. Self-reinforced composites (SRCs) are inexpensive, lightweight, and have advantages in terms of disposal and recycling as the reinforcement and the base material are composed of the same material. For this reason, it is attracting attention as a next-generation composite material to replace carbon fiber-reinforced composites used in aircraft.

    Korea Institute of Science and Technology (KIST, President Seok Jin Yoon) announced that Dr. Jaewoo Kim of the Solutions to Electromagnetic Interference in Future-mobility(SEIF), together with Prof. Seonghoon Kim of Hanyang University and Prof. O-bong Yang of Jeonbuk National University has successfully developed a 100% SRC using only one type of polypropylene (PP) polymer.

    Until now, in the manufacturing process of SRCs, chemically different components have been mixed in the reinforcement or matrix to improve fluidity and impregnation, resulting in poor physical properties and recyclability. The research team succeeded in controlling the melting point, fluidity, and impregnation by adjusting the chain structure of the polypropylene matrix through a four-axis extrusion process.

    The developed SRCs achieved the highest level of mechanical properties, with adhesion strength, tensile strength, and impact resistance improved by 333%, 228%, and 2,700%, respectively, compared to previous studies. When applied as a frame material for a small drone, the material was 52% lighter than conventional carbon fiber reinforced composites and the flight time increased by 27%, confirming its potential for next-generation mobility applications.

    Dr. Kim of KIST said, “The engineering process for 100% SRCs developed in this study can be immediately applied to industry, and we will continue to work with the joint research team and industries to secure the global competitiveness of magnetically reinforced composites.”

     

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    The research was funded by the National Research Council of Science & Technology(NST)’s Convergence Research Center Project (CRC22031-000) on “Development of Materials and Component Technologies for High Frequency/High Power Electromagnetic Wave Solutions to Secure Future Mobility Operation Reliability” (2016R1A6A1A03013422), the Korea Research Foundation’s Basic Research Project (2016R1A6A1A03013422), the Mid-Career Researcher Support Project (2021R1A2C11093839), and the Ministry of Education’s LINC 3.0. The results were published in the Chemical Engineering Journal (IF:16.744, top 2.448% in JCR), a world-class international journal in the field of chemical engineering.

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    National Research Council of Science and Technology

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  • Fungal networks used to knit futuristic eco-building designs

    Fungal networks used to knit futuristic eco-building designs

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    Newswise — Scientists hoping to reduce the environmental impact of the construction industry have developed a way to grow building materials using knitted molds and the root network of fungi. Although researchers have experimented with similar composites before, the shape and growth constraints of the organic material have made it hard to develop diverse applications that fulfil its potential. Using the knitted molds as a flexible framework or ‘formwork’, the scientists created a composite called ‘mycocrete’ which is stronger and more versatile in terms of shape and form, allowing the scientists to grow lightweight and relatively eco-friendly construction materials.

    “Our ambition is to transform the look, feel and wellbeing of architectural spaces using mycelium in combination with biobased materials such as wool, sawdust and cellulose,” said Dr Jane Scott of Newcastle University, corresponding author of the paper in Frontiers in Bioengineering and Biotechnology. The research was carried out by a team of designers, engineers, and scientists in the Living Textiles Research Group, part of the Hub for Biotechnology in the Built Environment at Newcastle University, which is funded by Research England.

    Root networks

    To make composites using mycelium, part of the root network of fungi, scientists mix mycelium spores with grains they can feed on and material that they can grow on. This mixture is packed into a mold and placed in a dark, humid, and warm environment so that the mycelium can grow, binding the substrate tightly together. Once it’s reached the right density, but before it starts to produce the fruiting bodies we call mushrooms, it is dried out. This process could provide a cheap, sustainable replacement for foam, timber, and plastic. But mycelium needs oxygen to grow, which constrains the size and shape of conventional rigid molds and limits current applications.

    Knitted textiles offer a possible solution: oxygen-permeable molds that could change from flexible to stiff with the growth of the mycelium. But textiles can be too yielding, and it is difficult to pack the molds consistently. Scott and her colleagues set out to design a mycelium mixture and a production system that could exploit the potential of knitted forms.

    “Knitting is an incredibly versatile 3D manufacturing system,” said Scott. “It is lightweight, flexible, and formable. The major advantage of knitting technology compared to other textile processes is the ability to knit 3D structures and forms with no seams and no waste.”

    Samples of conventional mycelium composite were prepared by the scientists as controls, and grown alongside samples of mycocrete, which also contained paper powder, paper fiber clumps, water, glycerin, and xanthan gum. This paste was designed to be delivered into the knitted formwork with an injection gun to improve packing consistency: the paste needed to be liquid enough for the delivery system, but not so liquid that it failed to hold its shape.

    Tubes for their planned test structure were knitted from merino yarn, sterilized, and fixed to a rigid structure while they were filled with the paste, so that changes in tension of the fabric would not affect the performance of the mycocrete.

    Building the future

    Once dried, samples were subjected to strength tests in tension, compression and flexion. The mycocrete samples proved to be stronger than the conventional mycelium composite samples and outperformed mycelium composites grown without knitted formwork. In addition, the porous knitted fabric of the formwork provided better oxygen availability, and the samples grown in it shrank less than most mycelium composite materials do when they are dried, suggesting more predictable and consistent manufacturing results could be achieved.

    The team were also able to build a larger proof-of-concept prototype structure called BioKnit – a complex freestanding dome constructed in a single piece without joins that could prove to be weak points, thanks to the flexible knitted form.

    “The mechanical performance of the mycocrete used in combination with permanent knitted formwork is a significant result, and a step towards the use of mycelium and textile biohybrids within construction,” said Scott. “In this paper we have specified particular yarns, substrates, and mycelium necessary to achieve a specific goal. However, there is extensive opportunity to adapt this formulation for different applications. Biofabricated architecture may require new machine technology to move textiles into the construction sector.”

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    Frontiers

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  • Thanks to Trapped Electrons, a Material Expected to be a Conducting Metal Remains an Insulator

    Thanks to Trapped Electrons, a Material Expected to be a Conducting Metal Remains an Insulator

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    The Science

    New research sheds light on the mechanism behind how a special material changes from an electrically conducting metal to an electric insulator. The researchers studied lanthanum strontium nickel oxide (La1.67Sr0.33NiO4) derived from a quantum material La2NiO4. Quantum materials have unusual properties that result from how their electrons interact. Below a critical temperature, the strontium doped material is an insulator. This is due to the separation of introduced holes from the magnetic regions, forming “stripes.” As the temperature increases, these stripes fluctuate and melt at 240K. At this temperature, researchers expected the material to become a conducting metal. Instead, it remains an insulating material. Neutron scattering sheds light on this intriguing phenomenon. The results indicate that the material stays an insulator because of certain atomic vibrations that trap electrons and thus impede electrical conduction.

    The Impact

    Quantum materials have properties that aren’t predicted by the parts that make up those materials. For example, they can transition from metals to insulators or act as superconductors. They hold tremendous promise for applications in science and technology. This research describes the tunability of electron-phonon interaction on the metal-insulator transition in one quantum material. The results will help validate theoretical models of materials that have strongly interacting electrons. These theories will help scientists design new quantum materials for future technologies.

    Summary

    In metals, electrons can be considered as free particles flying along trajectories enforced by the crystal structure. In recent decades, scientists discovered new materials where electrons strongly repel each other and bounce off atomic vibrations in the host crystal. These materials exhibit unusual and technologically useful properties. These properties can include dramatic electrical resistance drop in magnetic fields, electron conduction only on the surface, and high temperature superconductivity. Understanding these properties in different materials remains a grand challenge for the scientific community.

    This work used high intensity neutron beams at the Spallation Neutron Source, a Department of Energy user facility at Oak Ridge National Laboratory (ORNL), to look deep inside an archetype quantum material La2NiO4 in which one sixth of the lanthanum (La) atoms are replaced with strontium (Sr) atoms (La1.67Sr0.33NiO4). The team included researchers from the University of Colorado Boulder, ORNL, Brookhaven National Laboratory, and the RIKEN Center for Emergent Matter Science in Japan. These materials are insulating at low temperatures due to the so-called “stripe” order that results from the complex interplay between electronic spins and the holes introduced due to strontium doping. The doped material is expected to become metallic above 240K when the stripes melt. However, the material remains insulating. The collaboration uncovered strong friction between the holes and certain vibrations of oxygen ions and found evidence for this interaction in other materials of similar structure. The microscopic mechanism could pave way for the design of new materials with unusual properties useful for various quantum technologies.

     

    Funding

    Work at the University of Colorado Boulder was supported by the Department of Energy Office of Science, Basic Energy Sciences program. One of the researchers was supported by a Japan Science and Technology Agency CREST Grant. Work at Brookhaven National Laboratory was supported by the Department of Energy Office of Science, Basic Energy Sciences program.


    Journal Link: Scientific Reports, Jul-2020

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    Department of Energy, Office of Science

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  • Termite-inspired air conditioning for climate-friendliness

    Termite-inspired air conditioning for climate-friendliness

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    Newswise — The climate control used by termites in their mounds could inspire tomorrow’s climate-smart buildings. New research from Lund University in Sweden shows that future buildings inspired by the termites could achieve the same effect as traditional climate control, but with greater energy efficiency and without its carbon dioxide footprint.

    Termite mounds have a sophisticated ventilation system that enables air circulation throughout the structure. This helps to maintain and regulate temperature and humidity.

    “The digitalisation of design and construction processes creates enormous opportunities for how we shape architecture, and natural and biological systems provide an important model for how we can best utilise these possibilities,” says David Andréen, senior lecturer at the Department of Architecture and Built Environment at Lund University, who wrote the article.

    The results, published in the journal Frontiers in Materials, show a structure for buildings based on termite mounds that facilitates indoor climate control.

    “The study focuses on the interior of termite mounds, which consist of thousands of interconnected channels, tunnels and air chambers, and how these capture wind energy in order to “breathe,” or exchange oxygen and carbon dioxide with the surroundings. We have explored how these systems work and how similar structures could be integrated in the walls of buildings to drive the flow of air, heat and moisture in a new way.”

    The idea is thus to create new ways to control the airflow in buildings that will be significantly more energy-efficient and climate-smart than traditional air conditioning, which uses the bulk flow principle, normally driven by fans. Instead, it is possible to develop systems that are turbulent, dynamic and variable.

    “These can be controlled by very small equipment and require minor energy provision,” says David Andréen.

    In the study, the researchers demonstrated how airflows interact with geometry – the parameters in the structure that cause the flows to arise and how they can be selectively regulated. These can be driven without using mechanical components such as fans, valves and similar, as only electronic control is required.

    “This a precondition for a distributed system in which many small sensors and regulating devices are placed in the climate-adaptive building envelope through miniaturisation, durability/sustainability and cost reduction,” says David Andréen.

    This enables regulation of the building’s indoor climate and to control factors such as temperature and humidity without relying on large fans and heating and air conditioning systems. The mechanisms are dependent on being able to create complex internal geometries (on the millimetre to centimetre scale), which is only possible using 3D printing. Through 3D printing, value can be added to the built environment to create sustainable architecture that otherwise would not have been possible.

    “It’s fascinating how the termites’ building process manages to create extremely complex well-functioning “engineering masterpieces”, without having the centralised control or drawings to refer to that we would need,” concludes David Andréen.
    https://www.frontiersin.org/articles/10.3389/fmats.2023.1126974/full

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    Lund University

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  • The chameleon effect

    The chameleon effect

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    Newswise — An elastic material that changes color, conducts electricity, can be 3D printed and is also biodegradable? That is not just scientific wishful thinking: Empa researchers from the Cellulose & Wood Materials laboratory in Dübendorf have produced a material with these exact properties on the basis of cellulose and carbon nanotubes.

    The researchers started with hydroxypropyl cellulose (HPC), which is commonly used as an excipient in pharmaceuticals, cosmetics and foodstuffs, among other things. When mixed with water HPC is known to form liquid crystals. These crystals have a remarkable property: Depending on their structure – which itself depends on the concentration of HPC, among other things – they shimmer in different colors, although they themselves have no color or pigment. This phenomenon is called structural coloring and is known to occur in nature: Peacock feathers, butterfly wings and chameleon skin get all or part of their brilliant coloration not from pigments, but from microscopic structures that “split” the (white) daylight into spectral colors and reflect only the wavelengths for specific colors.

    The structural coloring of HPC changes not only with concentration but also with temperature. To better exploit this property, the researchers, led by Gustav Nyström, added 0.1 weight percent carbon nanotubes to the mixture of HPC and water. This renders the liquid electrically conductive and allows the temperature, and thus the color of the liquid crystals, to be controlled by applying a voltage. Added bonus: The carbon acts as a broadband absorber that makes the colors deeper. By incorporating a small amount of cellulose nanofibers into the mixture, Nyström’s team was also able to make it 3D printable without affecting structural coloring and electrical conductivity.

    Sustainable sensors and displays

    The researchers used the novel cellulose mixture to 3D print various potential applications of the new technology. These included a strain sensor that changes color in response to mechanical deformation and a simple seven-segment display. “Our lab has already developed different disposable electronic components based on cellulose, such as batteries and sensors,” says Xavier Aeby, co-author of the study. “This is the first time we were able to develop a cellulose-based display.”

    In future, the cellulose-based ink could have many more applications, such as temperature and strain sensors, in food quality control or biomedical diagnostics. “Sustainable materials that can be 3D printed are of great interest, especially for applications in biodegradable electronics and the Internet of Things,” says Nyström, head of the laboratory. “There are still many open questions about how structural coloring is generated and how it changes with different additives and environmental conditions.” Nyström and his team aim to continue this line of work in the hope of discovering many more interesting phenomena and potential applications.

     

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    Empa, Swiss Federal Laboratories for Materials Science and Technology

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  • Joint research team from Korea and Germany seeks to enhance production efficiency of fuel cells with laser machining technology

    Joint research team from Korea and Germany seeks to enhance production efficiency of fuel cells with laser machining technology

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    Newswise — Fuel cells used for vessels and airplanes are becoming increasingly lighter to improve efficiency, and this is leading to a decline in the thickness of bipolar plate. In this regard, a laser machining technology for thin bipolar plate, which can help to enhance the production efficiency and quality of fuel cells, has been developed through international R&D innovative collaboration project.

    Through international joint research between Korea and Germany, the joint research team consisting of the Korea Institute of Machinery and Materials (President Sang-jin Park, hereinafter referred to as KIMM), an institute under the jurisdiction of the Ministry of Science and ICT, K-Lab (Representative Goo-cheol Kwon), a Korean small and medium-sized enterprise, and Germany’s Fraunhofer Gesellschaft and BBW Lasertechnik GmbH developed a new 2D on-the-fly* composite equipment by applying a scanner that allows for laser welding and cutting of materials for bipolar plates for fuel cells with thickness of 0.075mm.
    *2D laser scanner-stage real-time cross-coupling control technology (2D on-the-fly): 2D on-the-fly is a laser machining technology whereby the stage continuously moves through an algorithm that generates the optimal route, and the scanner corrects position errors.

    Principal Researcher Su-jin Lee of KIMM Department of Industrial Laser Technology and the joint research team focused their attention on the demands from fuel cell manufacturers that require the welding of large-scale thin plates of various forms as well as high-quality cutting at the same time. The joint research team used the conventional technology where the stage and the scanner move simultaneously, and succeeded in developing a Top-Lamp* composite processing machine capable of welding and cutting large areas (400mm x 400mm or larger) in various forms by cross-coupling the cutting gas output nozzle to the stage.

    *Top-Lamp: The name of the newly developed equipment, and it is also the name of the international joint project (Technology platform for advanced laser beam processes of metallic fuel cell plates).

    Additionally, the research team developed and utilized the function of maintaining machining accuracy by automatically correcting the work area through the same axle of the scanner and the vision system of the external angle in real-time. Using this function, a technology that enables the correction of the center position of the diameter of the nozzle throat and irradiation of the laser beam within 3mm from the diameter of the nozzle during the process has been applied. The hybrid composite equipment developed as above, which can perform high-speed welding and nozzle cutting at the same time, has been installed at and is being operated by BBW Lasertechnik GmbH, a German partner institution.
    *Irradiation: the act of exposing or directing laser beams onto a target material surface.

    With the conventional 2D on-the-fly technology, it has been difficult to precisely control the form of the material because of the change in speed caused by acceleration or deceleration at the time of turnaround (cornering) while the material is being processed. In addition, because it has also been difficult to make corrections to the machining process, it has been necessary to improve the quality thereof. Meanwhile, as it is not easy to attach cutting gas nozzles to conventional high-speed scanners, it has been necessary to use separate equipment for welding and cutting, which has led to increases in processing time and expense.

    The newly developed technology helps to enhance machining quality by reducing cross-coupling errors through a more precise position correction by the vision system of the scanner. Additionally, the cutting gas nozzle can be attached separately to the scanner or another stage, improving cutting quality. Furthermore, the vision system corrects the center position for laser beam irradiation at the nozzle throat. This allows high-speed welding and partial cutting at the same time, which helps reducing costs and processing time.

    Principal Researcher Su-jin Lee of KIMM was quoted as saying, “The German research team is also expecting that the latest technology, developed through international joint research, will be applicable to various sectors. The newly developed technology is meaningful in that it can respond to the demands from the fuel cell market for the improvement of machining quality as the thickness of bipolar plates for fuel cells becomes increasingly thinner.”

    Meanwhile, this research was carried out with the support of the project for the “development of advanced laser machining technologies for the manufacture of fuel cells,” an international co-development project of the Ministry of Trade, Industry and Energy. In May 2022, KIMM signed an MoU with Germany’s Fraunhofer Gesellschaft, one of the institutions that participated in the research, for the expansion of international cooperation and sustainable networking and cooperation among researchers in major fields.

    ###

    The Korea Institute of Machinery and Materials (KIMM) is a non-profit government-funded research institute under the Ministry of Science and ICT. Since its foundation in 1976, KIMM is contributing to economic growth of the nation by performing R&D on key technologies in machinery and materials, conducting reliability test evaluation, and commercializing the developed products and technologies.

    This research was carried out with the support of the project for the “development of advanced laser machining technologies for the manufacture of fuel cells,” an international co-development project of the Ministry of Trade, Industry and Energy.

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    National Research Council of Science and Technology

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  • Rubbery Materials That Keep Their Bounce After a Beating

    Rubbery Materials That Keep Their Bounce After a Beating

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    Newswise — DURHAM, N.C. — When it comes to the environmental impacts of cars, much ink has been spilled on tailpipe emissions. But there’s another environmental threat from cars you might not think about: microplastic pollution.

    Car tires are made of rubber but also plastic polymers and other materials. Tiny bits of these materials, most a fraction the size of a grain of sand, slough off whenever tires rub against the road. Some are washed into soils and waterways; others enter the air, where their long-term effects on the health of humans and other living things are unknown.

    Duke chemistry professor Stephen Craig thinks we can do better. In a study published June 22 in the journal Science, he and colleagues describe a way to make rubbery materials an order of magnitude tougher, without compromising other aspects of their performance.

    Craig is part of a team from Duke and MIT that has been studying the molecular reactions within a class of flexible polymer-based materials called elastomers. Think rubber tires, the nitrile in medical gloves, or the silicone in soft contact lenses. What makes these materials amazing is the fact that they can be stretched and squished repeatedly and still return to their original shape.

    But they’re not indestructible. Enough strain and they begin to crack. Most methods to make such materials more durable invariably involve a trade-off, Craig said: Greater toughness for less elasticity, for example.

    The new study suggests it doesn’t always have to be a compromise. The secret lies in weak bonds embedded within the material that actually make it stronger.

    Zoom in close enough, and elastomers essentially look like a jumble of loosely coiled strings or strands of spaghetti. Each strand is a long, chain-like molecule called a polymer, with covalent bonds called cross-links holding neighboring strands together.

    It’s the cross-links that help such materials hold their shape. Pulling on the material stretches the tangled polymer chains and makes them straight. Let it go, and they relax back into their more coiled and bunched-up state.

    For the new study, the team’s idea was to tie some of the polymer chains together using weak cross-links that are designed to break.

    In their work, the researchers designed and synthesized two identical elastomers composed of polyacrylate, a rubbery polymer used to make things like hoses, seals and gaskets. Then in one of them, they replaced the cross-links with ones that were five times weaker, due to an embedded molecule that breaks apart under strain — in this case a ring-shaped molecule called cyclobutane.

    Everything else being equal, Craig said, you’d think that “linkers that break more easily should produce materials that are easier to tear.”

    But instead they found the opposite. “Surprisingly, the overall network got much stronger as opposed to weaker,” he added.

    In mechanical tests, the researchers loaded thin sheets of each material into a machine that measures the force it takes to rip a sample.

    Both were similar in terms of stiffness and elasticity, but the one made with weak cross-linkers was up to nine times more difficult to tear than the one cross-linked with stronger bonds.

    “The toughness enhancement comes without any other significant change in physical properties, at least that we can measure, and it is brought about through the replacement of only a small fraction of the overall material,” Craig said.

    Tearing in a polymer material is essentially a chemical reaction, said first author Shu Wang, who did the work as part of his Ph.D. dissertation under Craig and Duke polymer theorist Michael Rubinstein.

    Typically, the polymer strands that span the leading edge of the tear must break for the crack to spread.

    But in their design the weak cross-links break first, leaving the main polymer thread uncinched but otherwise intact. This helps the material resist breaking down further, even once small nicks and blemishes start to form.

    The team has filed a patent on the approach. Much work remains to be done to use the insights to design tougher synthetic rubber like that found in tires, Craig said.

    “But that’s the long-term application I’m most excited about.”

    Previous studies estimate that, each year, tires release some 6 million metric tons of dust and debris worldwide, accounting for as much as 10% of the microplastics that end up in the oceans, and 3-7% of the particulate matter in the air we breathe.

    “That’s just from tire tread wearing down on roads,” Craig said. “If you could reduce that by even 10%, that’s still 600,000 tons of microplastics you’d be keeping out of the environment.”

    “So I’m really excited to see how these kinds of ideas might translate to that problem,” Craig said.

    This research was supported by the Center for the Chemistry of Molecularly Optimized Networks, or MONET, which is funded by the National Science Foundation (CHE-2116298).

    CITATION: “Facile Mechanochemical Cycloreversion of Polymer Cross-Linkers Enhances Tear Resistance,” Shu Wang, Yixin Hu, Tatiana B. Kouznetsova, Liel Sapir, Danyang Chen, Abraham Herzog-Arbeitman, Jeremiah A. Johnson, Michael Rubinstein, Stephen L. Craig. Science, June 23, 2023. DOI: 10.1126/science.adg3229

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    Duke University

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  • BGSU researchers develop ‘green chemistry’ method to recycle, upcycle silicone

    BGSU researchers develop ‘green chemistry’ method to recycle, upcycle silicone

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    Newswise — Pioneering research out of Bowling Green State University is aiming to keep silicone out of landfills through an innovative process designed to recycle or upcycle the popular consumer product.

    Dr. Joe Furgal, associate professor in the BGSU Chemistry Department, is spearheading a research project studying the use of room-temperature depolymerization to repurpose silicone, saving massive amounts of energy required to create new polymers. 

    Used to make everything from gaskets to cinematic masks, silicone has a clear life cycle gap, Furgal said. After consumer use, there currently is no easy way to turn the material back into its original form and be reused like other materials. 

    “After you use it, you just throw it away because silicones aren’t recycled,” he said. “There’s no recycling number for silicone, and there’s not even really a good process for it out there.” 

    Green chemistry
    The process of turning silicones back into raw materials uses a process called depolymerization, which is the process of converting a polymer — with grouped subunits — back into a monomer or series of monomers that allows them to be reused.  

    Furgal’s lab uses a catalyst that breaks down the silicone’s bonds, a solvent to aid catalyst transfer into the silicone, followed by a calcium chloride bath to lock the new structure into place. The entire process takes place at room temperature. 

    The resulting liquid can be strained and reused in new silicone production — eliminating the energy-heavy first step of silicone creation. 

    “We can take silicones, silicone rubbers, elastomers, oil, and using catalysts at room temperature, we can convert them back to their starting material,” Furgal said. “After filtering, then you can put that right back into the initiator process to get back to silicone.” 

    The depolymerization method even can separate silicone from attached plastics without harming the latter as the solvent also kills any biohazards the silicone might have encountered during its first use.

    The patent-pending methodology has a promising future use that includes a grant from the National Heart, Lung and Blood Institute to study the enhanced use of silicone with the controlled release of nitric oxide to prevent infection and blood clotting, a collaboration with associate professor Dr. Alexis Ostrowski at BGSU and two biomedical engineering faculty members at the University of Georgia, Dr. Elizabeth Brisbois and Dr. Hitesh Handa.

    The researchers are hopeful these methods will be useful and wide-ranging in reducing carbon emissions caused by the initial creation of silicone and similar polymers. 

    “This research opens the possibility of depolymerizing these materials in mild conditions and at room temperature,” Edirisinghe said. “This process will save resources, energy and cost because it’s environmentally beneficial and will contribute to green chemistry and the sustainable use of resources.” 

    Wide appeal
    Medical applications account for significant amounts of silicone usage — in tubing, hearing aids, implantable devices and prosthetics — but silicone also has significant everyday usage in things like kitchen tools, pacifiers, baby bottles, caulking and even children’s toys such as Silly Putty.

    Dr. Kalani Edirisinghe, a postdoctoral research associate in Furgal’s lab, said that silicone and other similar polymers offer many benefits, but when these polymers are discarded, the process of replacing them means significant, new energy usage. 

    “Siloxane-based polymers are widely used in everyday materials because they are low toxicity, and they’re chemically, mechanically and thermally stable,” Edirisinghe said. “The high energy cost in producing these materials is lost when they are discarded without recycling or upcycling, which will be a waste of resources and energy.”

    Similar to steel production, the creation of siloxane-based polymers requires carbothermal reduction at temperatures higher than 3,600 degrees Fahrenheit.

    Conservative estimates indicate every produced kilogram of the metal silicon, which is used to make the polymer silicone, releases at least 10 times that amount of carbon dioxide — and humans produce about 1.5 million tons of silicone per year.

    “We wanted to make the silicone life cycle more like steel,” said Dr. Buddhima Rupasinghe ’22, the author of a review on silicone degradation processes whose research as a BGSU student was responsible for moving this technology forward.

    But silicone is unlike steel after it is used by consumers. Most post-consumer steel is collected and reused, and Furgal said he wanted to use this research to “close the loop,” by returning polymers to their original forms, allowing them to be reused. 

    “Our inspiration comes from steel, which is made by a very similar process to silicon — but steel has an 88% recycling rate,” he said. “Think about that: 88% of all steel is reused, and steel scrap uses about 75% less energy than new steel.”

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    Bowling Green State University

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  • UC Irvine scientists create long-lasting, cobalt-free, lithium-ion batteries

    UC Irvine scientists create long-lasting, cobalt-free, lithium-ion batteries

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    Newswise — Irvine, Calif., June 14, 2023 – In a discovery that could reduce or even eliminate the use of cobalt – which is often mined using child labor – in the batteries that power electric cars and other products, scientists at the University of California, Irvine have developed a long-lasting alternative made with nickel.

    “Nickel doesn’t have child labor issues,” said Huolin Xin, the UCI professor of physics & astronomy whose team devised the method, which could usher in a new, less controversial generation of lithium-ion batteries. Until now, nickel wasn’t a practical substitute because large amounts of it were required to create lithium batteries, he said. And the metal’s cost keeps climbing.

    To become an economically viable alternative to cobalt, nickel-based batteries needed to use as little nickel as possible.

    “We’re the first group to start going in a low-nickel direction,” said Xin, whose team published its findings in the journal Nature Energy. “In a previous study by my group, we came up with a novel solution to fully eliminate cobalt. But that formulation still relied on a lot of nickel.”

    To solve that problem, Xin’s team spent three years devising a process called “complex concentrated doping” that enabled the scientists to alter the key chemical formula in lithium-ion batteries as easily as one might adjust seasonings in a recipe.

    The doping process, Xin explained, eliminates the need for cobalt in commercial components critical for lithium-ion battery functioning and replaces it with nickel.

    “Doping also increases the efficiency of nickel,” said Xin, which means EV batteries now require less nickel to work – something that will help make the metal a more attractive alternative to cobalt-based batteries.

    Xin said he thinks the new nickel chemistry will quickly start transforming the lithium-ion battery industry. Already, he said, electric vehicle companies are planning to take his team’s published results and replicate them.

    “EV makers are very excited about low-nickel batteries, and a lot of EV companies want to validate this technique,” Xin said. “They want to do safety tests.”

    About the University of California, Irvine: Founded in 1965, UCI is a member of the prestigious Association of American Universities and is ranked among the nation’s top 10 public universities by U.S. News & World Report. The campus has produced five Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 36,000 students and offers 224 degree programs. It’s located in one of the world’s safest and most economically vibrant communities and is Orange County’s second-largest employer, contributing $7 billion annually to the local economy and $8 billion statewide. For more on UCI, visit www.uci.edu.

    Media access: Radio programs/stations may, for a fee, use an on-campus ISDN line to interview UCI faculty and experts, subject to availability and university approval. For more UCI news, visit news.uci.edu. Additional resources for journalists may be found at communications.uci.edu/for-journalists.

    NOTE TO EDITORS: PHOTO AVAILABLE AT
    https://news.uci.edu/2023/06/14/uc-irvine-scientists-create-long-lasting-cobalt-free-lithium-ion-batteries/

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    University of California, Irvine

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  • Heat transport in energy materials

    Heat transport in energy materials

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    Newswise — The NOMAD Laboratory researchers have recently elucidated on fundamental microscopic mechanisms that offer to tailor materials for heat insulation. This development advances the ongoing efforts to enhance energy efficiency and sustainability.

    The role of heat transport is crucial in various scientific and industrial applications, such as catalysis, turbine technologies, and thermoelectric heat converters that convert waste heat into electricity. Particularly in the context of energy conservation and the development of sustainable technologies, materials with high thermal insulation capabilities are of utmost importance. These materials allow to retain and utilize heat that would otherwise go to waste. Therefore, improving the design of highly insulating materials is a key research objective in enabling more energy-efficient applications.

    However, designing strongly heat insulators is far from trivial, despite the fact that the underlying fundamental physical laws are known for nearly a century. At a microscopic level, heat transport in semiconductors and insulators was understood in terms of the collective oscillation of the atoms around their equilibrium positions in the crystal lattice. These oscillations, called “phonons” in the field, involve zillions of atoms in solid materials and hence cover large, almost macroscopic length- and time-scales.

    In a recent joined publication in Physical Review B (Editors Suggestions) and Physical Review Letters, researchers from the NOMAD Laboratory at the Fritz Haber Institute have advanced the computational possibilities to compute thermal conductivities without experimental input at unprecedented accuracy. They demonstrated that for strong heat insulators the above-mentioned phonon picture is not appropriate. Using large-scale calculations on supercomputers at of the Max Planck Society, the North-German Supercomputing Alliance, and the Jülich Supercomputing Centre, they scanned over 465 crystalline materials, for which the thermal conductivity had not been measured yet. Besides finding 28 strong thermal insulators, six of which featuring an ultra-low thermal conductivity comparable to wood, this study shed light on a hitherto typically overseen mechanisms that allows to systematically lower the thermal conductivity. “We observed the temporary formation of defect structures that massively influences the atomic motion for an extremely short period of time”, says Dr. Florian Knoop (now Linköping University), first author of both publications. “Such effects are typically neglected in thermal-conductivity simulations, since these defects are so short-lived and so microscopically localised compared to typical heat-transport scales, that they are assumed to be irrelevant. However, the performed calculations showed that they trigger lower thermal conductivities”, adds Dr. Christian Carbogno, a senior author of the studies.

    These insights may offer new opportunities to fine-tune and design thermal insulators on a nanoscale level through defect engineering, potentially contributing to advances in energy-efficient technology.

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    FRITZ HABER INSTITUTE – MAX PLANCK SOCIETY

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  • Next-gen SF6-free equipment: Eco-friendly gas advances

    Next-gen SF6-free equipment: Eco-friendly gas advances

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    Newswise — Gas-insulated equipment (GIE) that utilizes the most potent greenhouse gas sulfur hexafluoride (SF6) as insulation and arc-quenching medium has been widely used in the power industry. Seeking eco-friendly insulating gas with advanced performance for next-generation SF6-free GIE is significant for the “net-zero” goal and sustainable development.

    A research team led by Xiaoxing Zhang of Hubei University of Technology in China and scientists from Wuhan University, Southeast University, North China Electric Power University, Université de Toulouse, Xi’an University of Technology, Schneider Electric and South China University of Technology recently summarized the advances in Eco-friendly gas insulating medium for next-generation SF6-free equipment. The review report was published in the journal iEnergy as the cover article on March 31, 2023.

    An overview of the SF6-based GIE, the emission and reduction policies of SF6 were introduced firstly to clarify the necessity of seeking eco-friendly insulating gas. “SF6 is one of the most potent greenhouse gases with a global warming potential of 25200 and an atmospheric lifetime of 3200 years. The power industry accounts for 80% of the SF6 consumption, which value reaches over 7000 tons in China. Various countries have established regulations on the use, recovery and treatment of SF6, promoting the development of eco-friendly insulating gas” said Prof. Zhang.

    Basic requirements for eco-friendly gas including environmental features, insulation & arc-quenching performance, stability, material compatibility, biosafety were proposed and the main categories containing traditional gas (CO2, N2, air), Perfluorocarbons and Trifluoroiodomethane, Fluorinated-nitrile(C4F7N), Fluorinated-ketones(C5F10O, C6F12O), Hydrofluro-Olefins (HFO-1234ze(E), HFO-1336mzz(E)) were introduced. The molecular design method of eco-friendly gas was also provided.

    Recent progress of various eco-friendly insulating gas in terms of dielectric insulation (in terms of AC/DC breakdown, LI breakdown, partial discharge, surface flashover), arc-quenching (in terms of particle compositions, thermodynamic properties, transport coefficients, radiation coefficients, post-arc dielectric breakdown properties), stability and decomposition (in terms of thermal, discharge stability, decomposition mechanism), materials compatibility (in terms of metal, epoxy resin, elastomer, Adsorbent), biosafety (in terms of LC50, target organ toxicity, by-products toxicity) were highlighted.

    Besides, the latest application of eco-friendly insulating gas in medium-voltage (MV), high-voltage (HV) scenarios as well as relevant maintenance-related technologies were summarized. “The C4F7N/CO2, C5F10O/air based gas insulated switchgear, gas insulated transmission line, ring main units, etc. have been developed by GE, ABB since 2016. The other fluorinated-free technology roadmap using technical air combined with vacuum interruption also have been focused.” Said Prof. Zhang.

    Although substantial efforts have been made in the field, several significant challenges remain that call for more solutions to achieve the next-generation SF6-free GIE in the future. The improvement of stability, interruption capacity, material compatibility is highly desired. The SF6 control and recycling, insulation coordination, scientific management of PFAS, etc. will hopefully steer the development of eco-friendly insulating gas and GIE.

    Prof. Zhang is currently the Dean of School of Electrical and Electronic Engineering, Hubei University of Technology. His research focuses on high voltage engineering and low-carbon electrical materials, including eco-friendly gas, SF6 disposal and resource conversion, degradable dielectric materials. He received the National Award for Technological Invention in 2014 and the Cheungkong Scholars Program in 2020.

     

    iEnergy, has multiple meanings, intelligent energy, innovation for energy, internet of energy, and electrical energy due to “i” is the symbol of current. iEnergy, publishing quarterly, is a cross disciplinary journal aimed at disseminating frontiers of technologies and solutions of power and energy. The journal publishes original research on exploring all aspects of power and energy, including any kind of technologies and applications from power generation, transmission, distribution, to conversion, utilization, and storage. iEnergy provides a platform for delivering cutting-edge advancements of sciences and technologies for the future-generation power and energy systems.

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    Tsinghua University Press

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  • KIMM takes the lead in supporting commercialization of environment-friendly hydrogen vessels

    KIMM takes the lead in supporting commercialization of environment-friendly hydrogen vessels

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    Newswise — While climate change has made it an imperative to develop carbon neutral technologies, the infrastructure that can contribute to the development and commercialization of technologies related to environment-friendly vessels for the domestic shipbuilding sector has been established.

    The Korea Institute of Machinery and Materials (President Sang-jin Park, hereinafter referred to as KIMM), an institute under the jurisdiction of the Ministry of Science and ICT, through joint research with Korean Register (Representative Hyung-cheol Lee) and Pusan National University (President Jeong-in Cha), has established the infrastructure including the equipment necessary for evaluating the compatibility of materials for storing liquid hydrogen used for vessels, and has also proposed the evaluation process for the first time in the country.

    To establish the infrastructure, the research team led by Jong-won Park, Head of the Department of Reliability Assessment of the KIMM’s Mechanical Systems Safety Research Division, and Yong-jin Kim, Senior Researcher, through joint research with KIMM’s Department of 3D Printing and Pusan National University, has procured the equipment for testing, evaluating, and analyzing ultra-low temperatures (minus 253 degrees Celsius) and hydrogen embrittlement*. In addition, the research team has also published a report on the selection of materials for storing liquid hydrogen used for vessels, in which it analyzed the safety standards for various sectors of hydrogen storage and methods for assessing the compatibility of materials.
    *Hydrogen embrittlement: Reduction in the ductility of a metal due to absorption of hydrogen

    Storage systems for liquid hydrogen used for vessels must be capable of withstanding ultra-low temperatures and hydrogen embrittlement. As the system environment differs depending on the purposes of utilization and operation of the hydrogen to be stored, the type of materials that conform to the conditions of the environment also varies. Therefore, it is important to establish standards that reflect the dangerousness of ultra-low temperatures and the unique features of vessels.

    However, not only domestically but also globally, there have been no safety regulations that correspond to various conditions such as ultra-low temperatures and the unique characteristics of vessels. As a result, companies have been facing challenges in making inroads into the market for environment-friendly vessels. Based on latest research, the newly published report proposes materials and requirements that are applicable to the liquid hydrogen environment, while analyzing the differences with the materials and requirements applicable to domestic LNG storage systems, and also laying out standards under a variety of environments, which is expected to contribute to the development of technologies for eco-friendly vessels.

    Meanwhile, even in advanced countries, only a very limited number of research institutes have the equipment for evaluating and testing the compatibility of materials for ultra-low temperatures and hydrogen environments. Consequently, significant expenses are incurred for the test and evaluation processes, causing setbacks in domestic material and equipment manufacturers’ attempts to make inroads into the hydrogen industry.

    In order to help overcome these challenges, KIMM has prepared initiatives to support domestic shipbuilders in such sectors as “testing of the capacity of ultra-low temperature materials,” “assessment of compatibility to the hydrogen environment of materials and parts,” and “testing and durability assessment in a variety of extreme environments,” on the basis of the newly established infrastructure for testing, evaluating, and analyzing ultra-low temperatures and hydrogen embrittlement.

    Up until now, to develop the equipment and materials for environment-friendly vessels equipped with new materials, corporations have been paying additional expenses amounting to tens or even hundreds of millions of won just for the test and evaluation of materials. Now, it is expected that not only test and evaluation, but also analysis and technical support will be provided domestically at relatively low costs.

    Senior Researcher Yong-jin Kim was quoted as saying, “By establishing the standards for evaluating the compatibility of materials, we can expand the scope of applicable materials, which will likely help to expedite the commercialization of hydrogen vessels. Through the provision of test and evaluation services, we will make our outmost efforts so that Korean shipbuilders can secure a dominant position in the market for environment-friendly vessels.”

    The establishment of the infrastructure for the test and evaluation of ultra-low temperature materials has been carried out with the support of the “project to develop safety standards for the storage and fuel supply system for hydrogen for vessels” implemented by the Ministry of Oceans and Fisheries.

     

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    The Korea Institute of Machinery and Materials (KIMM) is a non-profit government-funded research institute under the Ministry of Science and ICT. Since its foundation in 1976, KIMM is contributing to economic growth of the nation by performing R&D on key technologies in machinery and materials, conducting reliability test evaluation, and commercializing the developed products and technologies.

    The establishment of the infrastructure for the test and evaluation of ultra-low temperature materials has been carried out with the support of the “project to develop safety standards for the storage and fuel supply system for hydrogen for vessels” implemented by the Ministry of Oceans and Fisheries.

     

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    National Research Council of Science and Technology

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  • Termite mounds inspire energy-efficient buildings

    Termite mounds inspire energy-efficient buildings

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    Newswise — Among the approximately 2,000 known species of termites, some are ecosystem engineers. The mounds built by some genera, for example Amitermes, Macrotermes, Nasutitermes, and Odontotermes, reach up to eight meters high, making them some of the world’s largest biological structures. Natural selection has been at work improving the ‘design’ of their mounds over tens of millions of years. What might human architects and engineers learn if they go to the termites and consider their ways?

    In a new study in Frontiers in Materials, researchers showed how termite mounds can teach us to create comfortable interior climates for our buildings that don’t have the carbon footprint of air conditioning.

    “Here we show that the ‘egress complex’, an intricate network of interconnected tunnels found in termite mounds, can be used to promote flows of air, heat, and moisture in novel ways in human architecture,” said Dr David Andréen, a senior lecturer at the bioDigital Matter research group of Lund University, and the study’s first author.

    Termites from Namibia

    Andréen and co-author Dr Rupert Soar, an associate professor at the School of Architecture, Design and the Built Environment at Nottingham Trent University, studied mounds of Macrotermes michaelseni termites from Namibia. Colonies of this species can consist of more than a million individuals. At the heart of the mounds lie the symbiotic fungus gardens, farmed by the termites for food.

    The researchers focused on the egress complex: a dense, lattice-like network of tunnels, between 3mm and 5mm wide, which connects wider conduits inside with the exterior. During the rainy season (November through April) when the mound is growing, this extends over its north-facing surface, directly exposed to the midday sun. Outside this season, termite workers keep the egress tunnels blocked. The complex is thought to allow evaporation of excess moisture, while maintaining adequate ventilation. But how does it work?

    Andréen and Soar explored how the layout of the egress complex enables oscillating or pulse-like flows. They based their experiments on the scanned and 3D-printed copy of an egress complex fragment collected in February 2005 from the wild. This fragment was 4cm thick with a volume of 1.4 liters, 16% of which were tunnels.

    They simulated wind with a speaker that drove oscillations of a CO2-air mixture through the fragment, while tracking the mass transfer with a sensor. They found that air flow was greatest at oscillation frequencies between 30Hz and 40 Hz; moderate at frequencies between 10Hz and 20 Hz; and least at frequencies between 50Hz and 120 Hz.

    Turbulence helps ventilation

    The researchers concluded that tunnels in the complex interact with wind blowing on the mound in ways that enhance mass transfer of air for ventilation. Wind oscillations at certain frequencies generate turbulence inside, whose effect is to carry respiratory gases and excess moisture away from the mound’s heart.

    “When ventilating a building, you want to preserve the delicate balance of temperature and humidity created inside, without impeding the movement of stale air outwards and fresh air inwards. Most HVAC systems struggle with this. Here we have a structured interface that allows the exchange of respiratory gasses, simply driven by differences in concentration between one side and the other. Conditions inside are thus maintained,” explained Soar.

    The authors then simulated the egress complex with a series of 2D models, which increased in complexity from straight tunnels to a lattice. They used an electromotor to drive an oscillating body of water (made visible with a dye) through the tunnels, and filmed the mass flow. They found, to their surprise, that the motor needed to move air back and forth only a few millimeters (corresponding to weak wind oscillations) for the ebb and flow to penetrate the entire complex. Importantly, the necessary turbulence only arose if the layout was sufficiently lattice-like.

    Living and breathing buildings

    The authors conclude that the egress complex can enable wind-powered ventilation of termite mounds at weak winds.

    “We imagine that building walls in the future, made with emerging technologies like powder bed printers, will contain networks similar to the egress complex. These will make it possible to move air around, through embedded sensors and actuators that require only tiny amounts of energy,” said Andréen.

    Soar concluded: “Construction-scale 3D printing will only be possible when we can design structures as complex as in nature. The egress complex is an example of a complicated structure that could solve multiple problems simultaneously: keeping comfort inside our homes, while regulating the flow of respiratory gasses and moisture through the building envelope.”

    “We are on the brink of the transition towards nature-like construction: for the first time, it may be possible to design a true living, breathing building.”

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    Frontiers

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