The MPIF has announced Edwin Pope, principal analyst at IHS Markit, as the keynote speaker for the co-located conferences WorldPM2020, AMPM2020, and Tungsten2020, taking place from 27 June–1 July 2020, in Montreal, Canada.
During the opening general session on 28 June 2020, Pope will discuss outlooks and trends for the global automotive market, propulsion system design, transmission design, electrification, and metal 3D printing within the automotive sector.
This story uses material from the MPIF, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
AIMPLAS says that the fifth edition of its compounding workshop, entitled ‘The Art of Mixing, Reinforcing and Incorporating Additives to Plastics’ will be held at its headquarters in Valencia, Spain, on 12 and 13 May 2020.
This workshop is reportedly designed for companies interested in increasing their knowledge of compounding, particularly with regard to techniques such as plastics mixing, reinforcing, additivation and co-rotating twin screw extrusion, and with interest in screw design, control processes, co-rotating twin screw extrusion and troubleshooting, as well as practical training.
Renishaw Inc has appointed Denis Zayia as the new president of its US operations.
Zayia has previously worked at Renishaw as coordinate measuring machine business manager and became national sales manager for industrial metrology. He has also been responsible for Renishaw's line of industrial metrology and additive manufacturing products.
‘Renishaw has been developing industry-changing products and end-to-end solutions for over 40 years,’ said Zayia. ‘Our first product was a touch-trigger probe, which was developed to solve a manufacturing problem on Concorde engines. Today, we are helping manufacturers driven by the goals of Industry 4.0 with a wide range of technologies including additive, motion control, healthcare, spectroscopy, quality assurance and process control. I am incredibly excited about the opportunity to lead the organization through its next phase of growth.’
This story uses material from Renishaw, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
You don't need a big laser to make laser-induced graphene (LIG). Scientists at Rice University, the University of Tennessee, Knoxville (UT Knoxville) and Oak Ridge National Laboratory (ORNL) are using a very small visible beam to burn the foamy form of carbon into microscopic patterns.
The labs of Rice chemist James Tour, which discovered the original method for turning a common polymer into graphene in 2014, and Tennessee/ORNL materials scientist Philip Rack revealed that they can now watch the conductive material form by making small traces of LIG in a scanning electron microscope (SEM).
The altered process, reported in a paper in ACS Applied Materials & Interfaces, creates LIG with features more than 60% smaller than the macro version and almost 10 times smaller than typically achieved with the former infrared laser. Lower-powered lasers also make the process less expensive, Tour said, which could lead to wider commercial production of flexible electronics and sensors.
"A key for electronics applications is to make smaller structures so that one could have a higher density, or more devices per unit area," Tour said. "This method allows us to make structures that are 10 times denser than we formerly made."
To prove the concept, the lab made flexible humidity sensors that are invisible to the naked eye and directly fabricated on polyimide, a commercial polymer. The devices were able to sense human breath with a response time of 250 milliseconds.
"This is much faster than the sampling rate for most commercial humidity sensors and enables the monitoring of rapid local humidity changes that can be caused by breathing," said the paper's lead author, Rice postdoctoral researcher Michael Stanford.
The smaller lasers pump light at a wavelength of 405nm, in the blue-violet part of the spectrum. These are less powerful than the industrial lasers used by the Tour group and others around the world to burn graphene into plastic, paper, wood and even food. The SEM-mounted laser burns only the top 5µm of the polymer, writing graphene features as small as 12µm.
Working directly with ORNL let Stanford capitalize on the national lab's advanced equipment. "That's what made this joint effort possible," Tour said.
"I did a lot of my PhD research at ORNL, so I was aware of the excellent facilities and scientists and how they could help us with our project," Stanford said. "The LIG features we were creating were so small that they would have been next-to-impossible to find if we were to lase the patterns and then search for them in the microscope later."
Tour, whose group recently introduced flash graphene to instantly turn trash and food waste into the valuable material, said the new LIG process offers a novel path toward writing electronic circuits into flexible substrates like clothing. "While the flash process will produce tons of graphene, the LIG process will allow graphene to be directly synthesized for precise electronics applications on surfaces," Tour said.
This story is adapted from material from Rice University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
If you have this kind of cut-and-paste growth and removal, combined with the different functionality of putting single-crystal oxide materials together, you have a tremendous possibility for making devices and doing scienceChang-Beom Eom
Researchers from the University of Wisconsin-Madison and MIT have created a new method for stacking ultrathin and complex oxide single-crystal layers that can produce stacked-crystal materials in nearly infinite combinations. The breakthrough could improve high-tech electronic devices due to the diverse functional properties of complex oxides, seen as crucial to the development of new components for applications such as data storage, sensing, energy technologies and biomedical devices.
As the geometrically arranged atoms of complex oxide single-crystal layers have useful magnetic, conductive and optical properties, the innovative platform and crystal-stacking process described in the journal Nature [Kum et al. Nature (2020) DOI: 10.1038/s41586-020-1939-z], could be used to develop structures with hybrid properties and a range of functions, as producing perfect interfaces while coupling different classes of complex materials allows new behaviors and tunable properties.
The researchers had previously added an ultrathin intermediate layer of graphene, before using epitaxy – where a material is deposited on top of another material in an orderly way – to grow a thin semiconducting material layer on top, with the grapheme acting as a peel-away backing since it is only a single molecule thick and therefore has weak bonding. This left a freestanding ultrathin sheet of semiconducting material.
Here, their layering method managed to overcome a key issue with conventional epitaxy in that every new oxide layer must be very compatible with the atomic structure of the underlying layer. If they align as a mismatch, the layers won’t stack properly. In the conventional method, a perfect single crystal can be grown on top of a substrate, but there is a problem in that growing the next material the structure must be the same and the atomic spacing similar, a constraint to growth.
For instance, while magnetic materials and piezoelectric materials cannot be grown on top of each other as they have different crystal structures, but with this method the layers can be grown separately, and then peeled off and integrated. The team showed the effectiveness of their approach with materials including perovskite, spinel and garnet, and they also can stack single complex oxide materials and semiconductors.
Such complex oxide materials can have a broad range of tunable properties that most other materials do not have but are significantly more difficult to grow and integrate, so the peel-away approach was effective. As team leader Chang-Beom Eom said, “If you have this kind of cut-and-paste growth and removal, combined with the different functionality of putting single-crystal oxide materials together, you have a tremendous possibility for making devices and doing science”.
Pyrite (iron sulphide, FeS2, also known as “fool’s gold”) is a widespread mineral found in deep sea sediments ,  and many rocks and minerals , . This includes those enriched with kerogen, the insoluble organic deposit that can accompany and generate oil. Typical organic precursors of kerogen are algae and woody plants.
The origins of pyrite deposits vary, but one particularly noteworthy form of pyrite frequently encountered in rocks is referred to as “framboids”, due to the raspberry-like appearance of spherical clusters of approximately equiaxed submicron particles that can be either rounded or polygonal in shape. These pyrite arrangements may carry a coded message about the origins of their formation.
It has been proposed and discussed in the literature  that the confined and controlled space within the frustules of diatom algae offers a favourable environment for framboid formation. What has so far remained elusive is confirmation of whether the process of pyrite formation is a purely chemical, abiotic reaction of Fe2+ ions with H2S/HS− ions; or if alternatively it is a biotic process  that takes place at the surface of Gram positive and negative bacteria that exist in spherical colonies and are responsible for framboid production, and their observed morphology.
The magnetosomes of magnetotactic bacteria that are believed to serve as nanometer nuclei (seeds) for the precipitation of submicron pyrite grains in framboids  contain the necessary amount of iron to support pyrite formation, while surrounding organic matter serves as the source of H2S. Local temperature and chemical conditions govern the shape of pyrite grains in framboids allowing to form a variety of exterior habits characteristic of cubic crystals .
A fascinating outstanding question concerns when and how magnetotactic bacteria colonize the interior space of diatom frustules to enable the growth of pyrite framboids, what local thermodynamic conditions prevail, and what serves as the sources of iron and sulphur – intra- or extracellular – that control the kinetics of framboid growth. Two mechanisms of diatom frustule bacterial colonization and pyrite formation may be surmised: (a) endosymbiotic bacteria that settle inside living diatoms, as was recently shown for siderophores , or (b) bacteria such as Desulfovibrionales that colonize frustules after diatom cell apoptosis.
Diatomite silica rocks formed in the Earth crust from ancient deep sea sediments frequently contain heavy, viscous crude oil  as well as pyrite in the form of framboids . The direct evidence of morphological similarity between framboids found within diatoms, and those seen in mineral deposits provide a strong link to the prominent role played by diatoms in the occurrence of pyrite framboids in rock. The importance of pyrite in oily rocks is highlighted by the fact that at elevated temperature and pressure when silica rocks are formed from diatomaceous/radiolarian sediments, the presence of FeS2 pyrite catalyses the kerogen-to-oil transformation .
The cover image represents a typical example of intra-diatom framboids present in this case within the frustule of diatom Rhizosolenia antennata. The imaged diatom was found in benthos samples collected at Antarctic shores at 680?m depth in Prydz Bay, Cooperation Sea, in the area of Russian polar station Progress (69°22′25″S 76°22′18″E). The cores were collected from the deck of RV Akademik Fedorov research ship during the 2017–18 Russian Antarctic expedition. The corer of 0.25?m2 cross-sectional area was lowered to the seabed using steel line, and a plastic sample tube was sunk into the sea sediment to the depth of 15–20?mm. The lack of characteristic H2S odour from the withdrawn sample indicated aerobic conditions at probe site, suggesting the prevalence of endosymbiotic bacteria in framboid formation.
It is remarkable to observe the variety of diatom species seen in the background of the cover image that has been confirmed in our large area SEM imaging experiments. Diatom algae are photosynthesising, and capture carbon dioxide dissolved in sea water. The favourable conditions for diatom proliferation in the cold polar regions can perhaps be well described by the title of a book by Françoise Sagan, “Un peu de soleil dans l’eau froide”.
The significance of diatom algae in the oil formation process has been well documented, along with their prominent role in the global biomineralization during the present geological era. Deeper insights into the important stages of pyrite and kerogen formation via endosymbiotic bacteria route may be obtained through in vitro studies in bioreactors .
Nanostructured iron sulphide mineral pyrite particles have recently attracted strong attention as efficient materials for energy , charge storage  and photovoltaic  applications. Hence, aquaculture cultivation of diatom algae under appropriate carefully chosen conditions may open up new opportunities for nanobiotechnology  low-cost production of photovoltaic, energy storage, and optoelectronic devices.
Purposeful cultivation of symbiotic societies of diatoms and magnetotactic bacteria in bioreactors enhanced by rigorous control over media temperature and chemical composition, and external magnetic field may allow to guide the hierarchical framboid structure formation for novel nanostructured smart energy sources and provide a link to silicon electronics by localising diatoms at the surface of patterned wafer substrates .
Somerset Community College’s (SCC) additive manufacturing program has successfully 3D printed numerous 316L stainless steel metal parts on a range of low cost desktop 3D printers.
Several of these parts were then successfully tungsten inert gas (TIG) welded together. According to SCC, this project is one of the first applications where fully metal parts 3D printed on a US$600 desktop printer have been successfully welded together using conventional welding techniques.
The 3D printing process is based on bound metal additive manufacturing (BMAM), which said the college says could be one of the fastest growing methods of additive production over the next several years.
‘The welds flowed very smoothly and we had very good penetration control,’ said SCC senior welding professor, Karl Watson. ‘Because of the nature of 3D printing and research we have seen around the concept of welding such parts, I expected to see more porosity in the weld, but that wasn’t the case with these specimens at all.’
Preliminary testing of the parts has also shown hardness values slightly less than stock 316L, but microscopic inspection after finishing has not shown any inconsistencies thus far, SCC said. Watson also noted that the heat dissipation during the welding process of the 3D printed stainless was higher than conventional stock stainless.
This story uses material from SCC, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
America Makes has elected its new executive committee which it says will focus on strategy, policy, and advocacy.
The committee includes three appointed government representatives and eight representatives elected from non-profits, academia, and industry. Committee members serve two-year terms, America Makes says.
‘Our executive committees have always had membership diversification built into the structure,’ said executive director John Wilczynski. ‘However, this executive committee has an additional level of diversity with representation from every part of the additive manufacturing value chain. They will play an integral role in providing strategic guidance and sharing their unique perspectives as we continue to execute our mission.’
The members include:
Stephanie Gaffney, director, Youngstown Business Incubator (YBI)
Jeannine Kunz, vice president, Tooling U-SME.
Sandra DeVincent Wolf, director, Carnegie Mellon University
Ed Herderick, director, the Center for Design and Manufacturing Excellence (CDME), Ohio State University.
John Barnes, founder, the Barnes Group Advisors
Melanie Lang, co-founder and CEO, FormAlloy
Jim Monroe, AM director, American Additive Manufacturing, LLC
Brian Rosenberger, LM fellow, Lockheed Martin Aeronautics Company.
Raymond Clinton, associate director, NASA Marshall space flight center
Alan Pentz, AM implementation lead, US Navy
Mike McKittrick, program manager, US Department of Energy.
This story uses material from America Makes, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Polynt Reichhold Group says that it plans to establish and incorporate its fully owned subsidiary, Polynt Composites Turkey, based in Istanbul.
The new company will help grow and consolidate the presence of Polynt Reichhold Group in Turkey and the surrounding region, where industrial activities are expected to continue to build up in the next years, Polynt said. It will focus on supplying unsaturated polyester resins, vinyl ester resins, gelcoats and compounds for local composites applications in construction, engineering stone and transportation.
This story uses material from Polynt, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Eight students from India have come to WUST together with their tutor to spend four weeks in our city. Under the winter school programme, they will have laboratory classes and lectures at the university.
A new study has revealed good news for the possibility of using perovskite materials in next-generation solar cells. The study, reported in a paper in Acta Materialia, finds that although perovskite films tend to crack easily, those cracks are easily healed with some compression or a little bit of heat. That bodes well, the researchers say, for the use of inexpensive perovskites to replace or complement expensive silicon in solar cell technologies.
"The efficiency of perovskite solar cells has grown very quickly and now rivals silicon in laboratory cells," said Nitin Padture, professor in Brown University's School of Engineering and director of Brown's Institute for Molecular and Nanoscale Innovation. "Everybody's chasing high efficiency, which is important, but we also need to be thinking about things like long-term durability and mechanical reliability if we're going to bring this solar cell technology to the market. That's what this research was about."
Perovskites, a broad class of crystalline materials, were first incorporated into solar cells in 2009. Those first perovskite solar cells had a power conversion efficiency of around 4%, but this figure has now risen to more than 25% – essentially the same as traditional silicon solar cells. The advantage of perovskite solar cells is that they can be made for a fraction of the cost of silicon, potentially cutting the cost of solar power installations. Perovskites can also be made into thin films that are semi-transparent and flexible, clearing the way for energy-generating windows or for lightweight, flexible solar cells in tents or backpacks.
But the low-cost and ease of making perovskite solar cells comes at a cost. "In material science, things that are easy to make also tend to be easy to break," said Padture, who led the study. "That's certainly true of perovskites, which are quite brittle. But here we show they're also quite easy to fix – cracks in perovskite films can be healed by compressing them or with moderate heat."
For the study, Srinivas Yadavalli, a doctoral student working in Padture's laboratory and first author of the paper, deposited perovskite films on plastic substrates. He then bent the substrate to put tensile (pulling apart) stress on the perovskite film while using a scanning electron microscope (SEM) to detect cracks. Once the film was cracked, the researchers then bent the substrate in the opposite direction to see if compressive stress might heal those cracks.
Sure enough, SEM imaging showed that the cracks disappeared. To make sure the cracks were fully healed and not merely hidden, the researchers used a technique known as X-ray diffraction. By measuring the size of a material's atomic lattice, this technique can reveal whether a formerly cracked area is now able to carry a mechanical load – a clear sign that the crack is healed. Those tests also indicated fully healed cracks.
The researchers found that heat was just as effective in healing cracks. Temperatures of around 100°C – quite modest heating by material science standards – were enough to completely heal cracks in perovskite films.
Padture says that this study was aimed at better understanding the basic properties of perovskite materials, and more work now needs be done to develop methods for applying this information in a commercial setting. But knowing that perovskite films are easily healed could be useful as these kinds of solar cells move toward commercialization.
"It's good news," Padture said. "It suggests that fairly simple healing methods may help maintain performance in these kinds of solar cells."
This story is adapted from material from Brown University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
A team of researchers from the US and Germany, led by Leslie Schoop, assistant professor of chemistry at Princeton University, has uncovered a layered compound with a trio of properties not previously known to exist in one material.
In a paper in Science Advances, the team reports that the van der Waals material gadolinium tritelluride (GdTe3) displays the highest electronic mobility among all known layered magnetic materials. In addition, it has magnetic order and can easily be exfoliated. Combined, these properties make it a promising candidate for new areas like magnetic twistronic devices and spintronics, as well as advances in data storage and device design.
The Schoop team initially uncovered these unique characteristics in early 2018, shortly after beginning the project. Their first success was in demonstrating that GdTe3 is easily exfoliable down to ultrathin flakes with a thickness below 10nm.
Subsequently, the team spent two years refining the purity of these material crystals to a state that served to amplify the results. The lab has already shipped a number of samples to researchers eager to explore how the compound fits into a category previously occupied only by black phosphorous and graphite. High mobility is rare in layered materials.
The properties detailed in this study, described as quantum oscillations or ‘wiggles’ that can be measured, are so pronounced that they were observed without the special probes and equipment generally found in national laboratories.
"Usually, if you see these oscillations, it depends partly on the quality of your sample. We really sat down and made the best crystals possible," said Schoop. "Over the course of two years we improved the quality, so that these oscillations became more and more dramatic. But the first samples already showed them, even though with the first crystals we grew we didn't know exactly what we were doing."
"It was very exciting for us. We saw these results of highly mobile electrons in this material that we didn't expect. Of course, we were hoping for good results. But I didn't anticipate it to be as dramatic."
Shiming Lei, a postdoctoral research associate at Princeton University, characterized the news as a "breakthrough", largely because of the high mobility. "Adding this material into the zoo of 2D van der Waals materials is like adding a newly discovered ingredient for cooking, which allows for new flavors and dishes."
"So first, you get these materials out," he added "The next thing is identifying the potential: what is the function of the device you can make from it? What is the performance we can further improve as a next generation of materials along this line?"
A rare-earth tritelluride, GdTe3 has a carrier mobility beyond 60,000cm2V-1s-1. This means that if a field of 1 volt per cm is applied to the material, the electrons move with a net speed of 60,000cm per second. To compare, mobilities in other magnetic materials are often found to be only a few hundred cm2V-1s-1.
"High mobility is important because this means that electrons inside the materials are able to travel at high speeds with minimal scattering, thus reducing the heat dissipation of any electronic devices built from it," explained Lei.
Van der Waals materials – in which the layers are bound by a weak force – are the parent compounds of 2D materials. Researchers are studying them for use in fabricating next-generation devices and also for use in twistronics, first described in the science community only a few years ago. With twistronics, the layers of 2D materials are misaligned or twisted as they lay atop one another. The judicious misalignment of the crystal lattice can change its electrical, optical and mechanical properties in ways that may yield new opportunities for applications.
In addition, it was discovered some 15 years ago that van der Waals materials could be exfoliated down to the thinnest layer by using something as commonplace as scotch tape. This revelation excited many new developments in physics. Finally, 2D materials were only recently revealed to exhibit magnetic order, in which the spins of electrons are aligned to each other. All ‘thin’ devices – hard drives, for example – are based on materials ordering magnetically in different ways that produce different efficiencies.
"We have found this material where the electrons shoot through as on a highway – perfect, very easily, fast," said Schoop. "Having this magnetic order in addition and the potential to go to two dimensions is just something that was uniquely new for this material."
To fully understand the electronic and magnetic properties of GdTe3, the team collaborated with researchers at Boston College for exfoliation tests, and at Argonne National Laboratory and the Max Planck Institute for Solid State Research in Germany to understand the electronic structure of the material using synchroton radiation.
From a broader perspective, what satisfied Schoop most about the study was the "chemical intuition" that led the team to begin investigating GdTe3 in the first place. They suspected there would be promising results, but the fact that GdTe3 yielded them so quickly and emphatically is a sign, said Schoop, that chemistry has significant contributions to make to the field of solid-state physics.
"We're a group in the chemistry department and we figured out that this material should be of interest for highly mobile electrons based on chemical principles," said Schoop. "We were thinking about how the atoms were arranged in these crystals and how they should be bonded to each other, and not based on physical means, which is often understanding the energy of electrons based on Hamiltonians.
"But we took a very different approach, much more related to drawing pictures, like chemists do, related to orbitals and things like that. And we were successful with this approach. It's just such a unique and different approach in thinking about exciting materials."
This story is adapted from material from Princeton University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Additive Industries says that GKN Aerospace CTO Russ Dunn will officially open its latest process and application center near Bristol in the UK. According to the company, the center is part of a network of Additive Industries Competence Centres that are also located in Eindhoven, Los Angeles and Singapore, each having their own specialism in different aspects of industrial additive manufacturing. The UK & Ireland center’s core competence will be new materials and process development, Additive Industries said.
The center is located in Filton Aerospace Park, next to other aerospace, advanced engineering and manufacturing businesses such as Airbus, Rolls-Royce, and GKN.
This story uses material from Additive Industries, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Researchers at Northwestern University have developed a more efficient and stable method for conducting electrocatalytic reactions, which they report in a paper in CCS Chemistry.
The method, which involves fluidizing catalyst particles in electrolyte instead of gluing them to electrodes, avoids a rapid decline in reaction performance – a phenomenon researchers call fatigue. This approach could improve production processes for electrolysis and electrochemical energy conversion and storage.
"There has been extensive effort to find new high-performance catalysts that can also better withstand electrochemical reactions," said Jiaxing Huang, professor of materials science and engineering at Northwestern University’s McCormick School of Engineering, who led the research. "We developed a drastically different approach to make electrocatalysis less prone to decay – not by finding another new material, but by doing the reaction differently."
In a typical electrocatalysis process, catalytic materials are glued onto the electrode and then soaked in electrolyte, before undergoing a reaction spurred by a voltage. Since the voltage is continuously applied through the electrode, the materials experience continuous electrochemical stress. Over time, their catalytic performance can decay due to accumulated structural damage in the electrode as a whole and the degradation of individual particles.
The team's approach avoids this continuous stress by fluidizing the particles in the electrolyte. Now the particles work in rotation, experiencing electrochemical stress only momentarily when colliding with the electrode. Collectively, the output from the individual collision events merge into a continuous and stable electrochemical current.
"Fluidized electrocatalysis breaks the spatial and temporal continuum of electrochemical reactions, making the catalysts more efficient," explained Huang. "Fluidization also reduces the mass transport limit of the reactants to the catalyst, since the particles are swimming in the electrolyte."
Huang tested his ideas on a well-known, commercially available catalyst called Pt/C. This is made of carbon black powders decorated with platinum nanoparticles, and catalyzes oxygen evolution, hydrogen evolution and methanol oxidation reactions. When catalyzed by Pt/C, these three electrochemical reactions normally suffer from severe performance decay, but all showed higher efficiency and stability when the particles were fluidized.
"The new strategy makes an unstable catalyst deliver stable performance for all three of the model reactions. It was an exciting proof-of-concept," said Yi-Ge Zhou, the first author of the paper and a former visiting postdoc in Huang's group. "When we calculated single particle efficiency for some of these reactions, it was at least three orders of magnitude higher than the fixed particles. Instead of stressing them out, we gave the particles a chance to relax, and they became a lot more efficient as a result."
While more work is needed to identify the types of electrochemical reactions that could best benefit from fluidized electrocatalysis, Huang believes his method could be applied to a variety of different types of materials and produce more efficient, longer lasting electrocatalytic reactions. This could lead to improved electrochemical synthesis processes, which play an important role in converting energy to chemicals for large-scale energy storage.
"I hope other researchers consider our method to re-evaluate their catalysts. It would be exciting to see previously deemed unusable catalysts become usable," Huang said.
In many industrial processes, such as in bioreactors that produce fuels or pharmaceuticals, foam can get in the way. Frothy bubbles can take up a lot of space, limiting the volume available for making the product and sometimes gumming up pipes and valves, or damaging living cells. Companies spend an estimated $3 billion a year on chemical additives called defoamers, but these can affect the purity of the product and may require extra processing steps for their removal.
Now, researchers at Massachusetts Institute of Technology (MIT) have come up with a simple, inexpensive and completely passive system for reducing or eliminating the foam build-up, by using bubble-attracting sheets of specially textured mesh that make bubbles collapse as fast as they form. The new process is described in a paper in Advanced Materials Interfaces by recent graduate Leonid Rapoport, visiting student Theo Emmerich and professor of mechanical engineering Kripa Varanasi.
The new system uses surfaces the researchers call ‘aerophilic’, which attract and shed bubbles of air or gas in much the same way that hydrophilic (water-attracting) surfaces cause droplets of water to cling to a surface, spread out and fall away, Varanasi explains.
"Foams are everywhere" in industrial processes, he says, including beer brewing, paper making, oil and gas production and processing, biofuel generation, shampoo and cosmetics production, and chemical processing.
"It's one of the main challenges in cell culture or in bioreactors," he adds. To promote cell growth, various gases are typically diffused through the water or other liquid medium. But this can lead to a build-up of foam, and as the tiny bubbles burst they can produce shear forces that damage or kill the cells, so controlling the foam is essential.
The usual way of dealing with the foam problem is by adding chemicals such as glycols or alcohols, which typically then need to be filtered out again. But that adds cost and extra processing steps, and can affect the chemistry of the product. "How can you get rid of foams without having to add chemicals? That was our challenge," Varanasi says.
To tackle the problem, Varanasi and his colleagues created high-speed video in order to study how bubbles react when they strike a surface. They found that the bubbles tend to bounce away like a rubber ball, bouncing several times before eventually sticking in place, just as droplets of liquid do when they hit a surface, only upside down. (The bubbles are rising, so they bounce downward.)
"In order to effectively capture the impacting bubble, we had to understand how the liquid film separating it from the surface drains," explains Rapoport. "And we had to start at square one because there wasn't even an established metric to measure how good a surface is at capturing impacting bubbles. Ultimately, we were able to understand the physics behind what causes a bubble to bounce away, and that understanding drove the design process."
The team came up with a flat device that has a set of carefully designed surface textures at a variety of size scales. The surface was tuned so that bubbles would adhere right away without bouncing, and then quickly spread out and dissipate to make way for the next bubble instead of accumulating as foam.
"The key to quickly capturing bubbles and controlling foam turned out to be a three-layered system with features of progressively finer sizes," says Emmerich. These features help to trap a very thin layer of air along the surface of the material. This surface, known as a plastron, has similarities to the texture of some feathers on diving birds that help keep the animals dry underwater. In this case, the plastron helps to make the bubbles stick to the surface and dissipate.
The net effect is to reduce the time it takes for a bubble to stick to the surface by a hundredfold, Varanasi says. In tests, the bouncing time was reduced from hundreds of milliseconds to just a few milliseconds.
To test the idea in the lab, the team built a device containing a bubble-capturing surface and inserted it into a beaker that had bubbles rising through it. They placed that beaker next to an identical one with foaming suds and a sheet of the same size but without the textured material. In the beaker with the bubble-capturing surface, the foam quickly dissipated down to almost nothing, while a full layer of foam stayed in place in the other beaker.
According to Varanasi, such bubble-capturing surfaces could easily be retrofitted to many industrial processing facilities that currently rely on defoaming chemicals. He speculated that, in the longer run, such a method might even be used as a way to capture methane seeping from melting permafrost as the world warms. That could both prevent some of the potent greenhouse gas from making it into the atmosphere, and at the same time provide a source of fuel. At this point that possibility is "pie in the sky", he says, but in principle it could work.
Unlike many new technology developments, this system is simple enough that it could be readily implemented, Varanasi says. "It's ready to go. ... We look forward to working with industry."
This story is adapted from material from MIT, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Exact Metrology has opened a new facility in Illinois, adding to its existing facilities in Wisconsin, Ohio and an upcoming one in Texas.
According to the company, the location will offer training covering its range of design, testing and processing software including PolyWorks, Geomagic and PC-DMI, and contract services such as coordinate measuring machine (CMM) measurement, custom programming, inspection and reverse engineering.
This story uses material from Exact Metrology, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Spanish company Montefibre Carbon says that it has received €11.5 million from the Spanish Ministry of Industry, to produce polyacrylonitrile (PAN) precursor for conversion to carbon fiber with semi-aerospace quality and to build a flexible carbonization line.
The company is reportedly investing an additional €4.7 million in its plant in Miranda de Ebro, Spain.
Montefibre says that this investment will make it the third leading European producer of carbon fiber (after SGL from Germany and Solvay from Belgium). The line will also be the first owned by a Spanish company and the second to be installed in Spain (the first being the line built by Hexel in Illescas in 2008).
According to Montefibre, the new PAN precursor fiber will have a tensile strength of 700 ksi and will be marketed as M700. The new carbonization line, which will be operational by the end of 2021, will reportedly be able to work with fiber from 80K to 480K, up to a capacity of 100 tons per year.
‘The support of the Spanish Public Administration is essential to achieve the success of a project of the magnitude of Montefibre Carbon, which will be key to the industrial competitiveness of Spain, Castilla y León and Miranda de Ebro,’ said Alfonso Cirera Santasusana, CEO.
Montefibre Carbon says that it is also adapting four of its seven spinning lines to bring to market around 17,000 metric tons per year of its large-tow polyacrylonitrile (PAN) precursor for conversion to carbon fiber. The first precursor to reach the market will be an 80K tow in two industrial qualities, M500 (with a tensile strength of 500 ksi) and M600 (with a tensile strength of 600 ksi).
This story uses material from Montefibre Carbon, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Lithium batteries are found everywhere: they power smartphones, laptops, and electric bicycles and cars by storing energy in a very small space. This compact design is usually achieved by winding the thin sandwich of battery electrodes up into a cylindrical form, thereby ensuring they have large surfaces to facilitate high capacity and rapid charging.
An international team of researchers from the Helmholtz-Zentrum Berlin (HZB) in Germany and University College London in the UK has now investigated the surfaces of these wound electrodes during charging and discharging. To do this, they used, for the first time, a combination of two complementary tomography methods: X-ray tomography and neutron tomography. They report their findings in a paper in Nature Communications.
The researchers used X-ray tomography at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, to analyze the microstructure of the electrodes, and to detect deformations and discontinuities that develop during the charging cycles.
"Neutron tomography, on the other hand, made it possible to directly observe the migration of lithium ions and also to determine how the distribution of the electrolyte in the battery cell changes over time," explains Ingo Manke, a tomography expert at HZB.
The neutron tomography data were obtained mainly at the HZB BER II neutron source at the CONRAD instrument, one of the best tomography stations in the world. Additional data were obtained at the neutron source of the Institut Laue-Langevin (ILL) in Grenoble, where a first neutron imaging station is currently being set up with help from experts at HZB. Following the shutdown of BER II in December 2019, the CONRAD instrument will be transferred to ILL so that it will be available for future research.
The instrument at NeXT-Grenoble is able to simultaneously acquire x-ray and neutron tomography, and was essential to the process of obtaining the images featured in this article.Dr. Alessandro Tengattini, an ILL instrument scientist, had this to say: "We're demanding more power from our consumer electronics all the time. To make them more efficient, and also safe, we need to understand the minor fluctuations occurring inside the batteries throughout their lifetime. The electro-unrolling technique has enabled us to analyse the inside of batteries, while they are in use, to identify such minuscule fluctuations to almost the micrometre. It's hard to analyse Lithium with x-rays because it is a light-weight element, but in combination with high-flux neutrons provided at the Institut Laue-Langevin (ILL) researchers have been able to learn about the electro-chemical and mechanical properties at play simultaneously while these lithium-ion batteries are in use.”
A new mathematical method developed at the Zuse-Institut in Berlin, Germany, then allowed the physicists to virtually unwind the battery electrodes, as the cylindrical windings of the battery are difficult to examine directly. Only after mathematical analysis and the virtual unwinding could the researchers draw conclusions about the processes occurring at the individual sections of the electrodes.
"The algorithm was originally meant for virtually unrolling papyrus scrolls," explains Manke. "But it can also be used to find out exactly what happens in compact densely wound batteries."
"This is the first time we have applied the algorithm to a typical commercially available lithium battery," adds Tobias Arlt from HZB. "We modified and improved the algorithm in several feedback steps in collaboration with computer scientists of the Zuse-Institut."
Characteristic problems with wound batteries could be investigated using this method. For example, the researchers found that the inner windings exhibited completely different electrochemical activity (and thus lithium capacity) to the outer windings. In addition, the upper and lower parts of the battery each behaved very differently.
The neutron data also showed areas that experienced a lack of electrolyte, severely limiting the functioning of the respective electrode section. It also revealed that the anode is not equally well loaded and unloaded with lithium everywhere.
"The process we have developed gives us a unique tool for looking inside a battery during operation and analyzing where and why performance losses occur. This allows us to develop specific strategies for improving the design of wound batteries," concludes Manke.
Wearable tech and electronic cloth may be the way of the future, but getting there requires wiring that is strong, flexible and efficient. Such wiring may now have been developed by physicists at Michigan Technological University by threading conductive tellurium atomic chains through insulating boron nitride nanotubes (BNNT). In collaboration with colleagues at Purdue University, Washington University and the University of Texas at Dallas, the physicists report their work in a paper in Nature Electronics.
As demand for smaller and faster devices grows, scientists and engineers are turning to materials with properties that can deliver when existing ones lose their punch or can't shrink enough. For wearable tech, electronic cloth or extremely thin devices that can be laid over the surface of cups, tables, space suits and other materials, researchers have begun to tune the atomic structures of nanomaterials.
These nanomaterials need to bend as a person moves, but not go all noodly or snap. They also need to hold up under different temperatures and still provide enough juice to run the software functions users expect out of their desktops and phones.
BNNTs are hollow in the middle, highly insulating, and as strong and bendy as an Olympic gymnast. That made them a good candidate to pair with another material with great electrical promise: tellurium. Strung into atom-thick chains and threaded through the hollow center of BNNTs, the tellurium forms a tiny wire with immense current-carrying capacity.
"Without this insulating jacket, we wouldn't be able to isolate the signals from the atomic chains. Now we have the chance to review their quantum behavior," Yap said. "The is the first time anyone has created a so-called encapsulated atomic chain where you can actually measure them. Our next challenge is to make the boron nitride nanotubes even smaller."
A bare nanowire is kind of a loose cannon. Controlling its electronic behavior – or even just understanding it – is very difficult when it's in rampant contact with flyaway electrons. Nanowires of tellurium, which is a metalloid similar to selenium and sulfur, are expected to possess different physical and electronic properties than bulk tellurium. Researchers just needed a way to isolate it, which BNNTs now provide.
"This tellurium material is really unique. It builds a functional transistor with the potential to be the smallest in the world," said Peide Ye from Purdue University, who led the research.
Using transmission electron microscopy at the University of Texas at Dallas, the team was surprised to find that the atoms in these one-dimensional chains wiggle. "Silicon atoms look straight, but these tellurium atoms are like a snake. This is a very original kind of structure," Ye said.
The tellurium-BNNT nanowires allowed the creation of field-effect transistors only 2nm wide; current silicon transistors on the market are 10–20nm wide. The new nanowires current-carrying capacity reached 1.5×108 A cm-2, which beats most other semiconducting nanowires. Once encapsulated, the team assessed the number of tellurium atomic chains held within the nanotube, finding single and triple bundles arranged in a hexagonal pattern.
Additionally, the tellurium-filled nanowires are sensitive to light and pressure, another promising aspect for future electronics. The team also tried encasing the tellurium nanowires in carbon nanotubes, but their properties are not measurable due to the conducting or semiconducting nature of carbon.
While tellurium nanowires have been captured within BNNTs, like a firefly in a jar, much of the mystery remains. Before people begin sporting tellurium T-shirts and BNNT-laced boots, the nature of these atomic chains needs characterizing so that their full potential for wearable tech and electronic cloth can be realized.
Hexcel says that it plans to showcase a range of its materials for marine applications at JEC.
This includes its new HexBond 679 250 gsm epoxy adhesive film, which can be fully cured in only four hours at 80°C, and HexPly M79 prepregs for short cycle times, which can be cured at 70°C for eight hours or 80°C for four hours. When used with Hexcel’s air venting grid technology, HexPly M79 UD carbon tapes can be laminated with reduced debulking steps to produce void contents of less than 1%, the company said.
Also on show will be HexPly XF2 surfacing prepreg and HexPly SuperFIT prepregs, HexPly XF2, a drapable single ply prepreg surfacing solution, carbon fiber HexPly SuperFIT prepregs and the company’s new high modulus fiber, HexTow HM54.
The company also plans to display a scale model of the Gunboat 68 sailing catamaran which incorporates Hexcel’s HiMax carbon multiaxials and PrimeTex woven carbon fabrics in the hull and deck structures.
This story uses material from Hexcel, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Element Materials Technology (Element) has opened a powder characterization site for additive manufacturing (AM) at its lab in California, USA.
According to the company, powder characterization is required to ensure powder is authentic, pure, uniform and ready for processing. Element says that once the materials are printed it can also perform mechanical, dynamic, chemical and metallurgical testing on them.
Tests available include chemical composition analysis, powder sieve analysis, particle size distribution, flow rate, apparent density, tap density and gas pycnometry.
‘3D printing is well beyond an emerging market now and is an increasingly important space for us to be working and investing in,’ said Rick Sluiters, EVP at Element. ‘Powder characterization has applications in multiple industries, including aerospace and medical devices, which are key sectors for Element.’
This story uses material from Element, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
"In industry, there are so many reactions limited by water. This is the only membrane that can work highly efficiently under the harsh reaction conditions."Miao Yu, Rensselaer Polytechnic Institute
Methanol is a versatile and efficient chemical used in the production of countless products. Carbon dioxide (CO2), on the other hand, is a greenhouse gas that is the unwanted by-product of many industrial processes.
Converting CO2 to methanol is one way to put CO2 to good use. In a paper in Science, researchers from Rensselaer Polytechnic Institute demonstrated how to make the conversion process from CO2 to methanol more efficient by using a highly effective separation membrane they developed. This breakthrough, the researchers said, could improve a number of industry processes that depend on chemical reactions where water is a by-product.
The chemical reaction responsible for transforming CO2 into methanol also produces water, which severely restricts the continued reaction. The Rensselaer team set out to find a way to filter out the water as the reaction is happening, without losing other essential gas molecules.
Their approach involved assembling a membrane made up of sodium ions and zeolite crystals that was able to carefully and quickly permeate water through small pores – known as water-conduction nanochannels – without losing gas molecules.
"The sodium can actually regulate, or tune, gas permeation," said Miao Yu, a professor of chemical and biological engineering and a member of the Center for Biotechnology and Interdisciplinary Studies (CBIS) at Rensselaer, who led the research. "It's like the sodium ions are standing at the gate and only allow water to go through. When the inert gas comes in, the ions will block the gas."
In the past, Yu said, this type of membrane was susceptible to defects that would allow other gas molecules to leak out. But his team developed a new strategy to optimize the assembly of the crystals, which eliminated those defects.
When water was effectively removed from the process by the membrane, Yu said, the team found that the chemical reaction was able to happen very quickly. "When we can remove the water, the equilibrium shifts, which means more CO2 will be converted and more methanol will be produced," explained Huazheng Li, a postdoctoral researcher at Rensselaer and first author of the paper.
"This research is a prime example of the significant contributions Professor Yu and his team are making to address interdisciplinary challenges in the area of water, energy and the environment," said Deepak Vashishth, director of CBIS. "Development and deployment of such tailored membranes by Professor Yu's group promise to be highly effective and practical." The team is now working to develop a scalable process and a start-up company that would allow this membrane to be used commercially to produce high purity methanol.
According to Yu, the membrane could also be used to improve a number of other reactions. "In industry, there are so many reactions limited by water," he said. "This is the only membrane that can work highly efficiently under the harsh reaction conditions."
Scientists at the University of Groningen in the Netherlands have used a silver sawtooth nanoslit array to produce valley-coherent photoluminescence in two-dimensional (2D) tungsten disulfide flakes at room temperature. Until now, this could only be achieved at very low temperatures.
Coherent light can be used to store or transfer information in quantum electronics. As such, the novel plasmon-exciton hybrid device created by the scientists is promising for use in integrated nanophotonics (light-based electronics). The scientists report their work in a paper in Nature Communications.
Tungsten disulfide has interesting electronic properties and is available as a 2D material. “The electronic structure of monolayer tungsten disulfide shows two sets of lowest energy points or valleys,” explains associate professor Justin Ye, head of the Device Physics of Complex Materials group at the University of Groningen.
One possible application for 2D tungsten disulfide is in photonics, as it can emit light with valley-dependent circular polarization, which offers a new way to store and manipulate digital information. But valleytronics requires coherent and polarized light, and previous work showed that the photoluminescence polarization in tungsten disulfide is almost random at room temperature.
“Tungsten disulfide is unique in that these two valleys are not identical,” explains Ye. This means that to create linearly polarized light via photoluminescence, both valleys must respond coherently. “But the intervalley scattering at room temperature largely destroys the coherence, so appreciable coherence is only achieved at very low temperatures that are close to zero.”
Ye and his postdoctoral researcher Chunrui Han (now working at the Institute of Microelectronics, Chinese Academy of Sciences) tried a different approach to creating linearly polarized light. This involved using a plasmonic metasurface, in the form of a silver sawtooth nanoslit array. The array interacts strongly with tungsten disulfide and can transfer the electromagnetic field induced by the light to the metal. “It enhances the light-material interaction,” says Ye.
By adding a thin layer of silver metasurface on top of a monolayer of tungsten disulfide, Ye and Han were able to increase the linear polarization induced by the valley coherence to around 27% at room temperature. “This room temperature performance is even better than the valley polarization obtained in many previous reports measured at very low temperatures,” says Ye.
They could further increase the linear polarization to 80% by adding the anisotropy of plasmonic resonance, in the form of the sawtooth pattern, to the optical response of the tungsten disulfide. This means that Ye and Han can now induce linearly polarized photoluminescence in 2D tungsten disulfide.
This accomplishment will make it possible to use both the valley coherence of tungsten disulfide and the plasmonic coherence of metasurfaces in optoelectronics at ambient temperatures. The next step is to replace the laser light that induced photoluminescence with an electrical input.
GKN Hoeganaes says that its plant in Gallatin, TN, USA, has received a carbon reduction award by the Tennessee Valley Authority (TVA) for its effort in reducing its carbon footprint.
The company was recognized for having a ‘significant impact on carbon reduction as a result of lowering its peaks in demand’, the TVA said.
Over the last three years, GKN Hoeganaes has reportedly reduced its electricity usage by 183.04 lbs CO2/kWH by monitoring its overall peak load. To determine peak load, GKN and TVA monitor the CO2/kWH power used during its peak time compared to other energy consumption types like nuclear or hydro. By reducing peak loads, the company can achieve lower consumption of CO2emissions.
Its Gallatin plant has also implemented a program aimed at reducing its energy demand. By comparing maximum demand pulled over one-month (max demand), to the maximum demand pulled for a daily six-hour window over that same month (peak demand) GKN was able to identify opportunities to reduce energy usage, it said.
This story uses material from GKN, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Engineers strive to design smartphones with longer-lasting batteries, electric vehicles that can drive for hundreds of miles on a single charge, and a reliable power grid that can store renewable energy for future use. Each of these technologies is within reach – as long as scientists can build better cathode materials.
To date, the typical strategy for enhancing cathode materials has been to alter their chemical composition. But now chemists at the US Department of Energy (DOE)’s Brookhaven National Laboratory have uncovered a new finding about battery performance that points to a different strategy for optimizing cathode materials. Their research, reported in a paper in Chemistry of Materials, focuses on controlling the amount of structural defects in the cathode material.
"Instead of changing the chemical composition of the cathode, we can alter the arrangement of its atoms," said corresponding author Peter Khalifah, a chemist at Brookhaven Lab and Stony Brook University.
Today, most cathode materials are comprised of alternating layers of lithium ions and transition metals such as nickel. Within that layered structure, a small number of defects can usually be found. That means atoms from a transition metal can be found where a lithium ion is supposed to be and vice versa.
"You can think of a defect as a 'mistake' in the perfection of the material's structure," Khalifah said. "It is known that a lot of defects will lead to poor battery performance, but what we've come to learn is that a small number of defects should actually improve key properties."
There are two properties that a good cathode material should have: ionic conductivity (the lithium ions can move well) and electronic conductivity (the electrons can move well).
"The presence of a defect is like poking a hole between the lithium ion and transition metal layers in the cathode," he said. "Instead of being confined to two dimensions, the lithium ions and electrons can move in three dimensions across the layers."
To reach this conclusion, the scientists needed to conduct high-precision experiments that measured the concentration of defects in a cathode material with far greater accuracy than has ever been done before.
"The concentration of defects in a cathode material can vary between 2% and 5%," Khalifah said. "Before, defects could only be measured with a sensitivity of about 1%. In this study, we measured defect concentration with exquisite accuracy – a sensitivity of a tenth of a percent."
To achieve this precision, the scientists conducted powder diffraction analyses using data from two DOE Office of Science User Facilities, the Advanced Photon Source (APS) at DOE's Argonne National Laboratory and the Spallation Neutron Source (SNS) at DOE's Oak Ridge National Laboratory. Powder diffraction is a powerful research technique that reveals the location of individual atoms within a material by directing beams of X-rays, neutrons or electrons at the material and studying how the beams diffract. In this study, the scientists conducted X-ray measurements at APS and neutron measurements at SNS.
"This work has developed a new way of visualizing structural defects and their relationship to diffraction and scattering strength," said Saul Lapidus, a physicist in the X-ray Science Division at APS. "I expect in the future for this technique to be used commonly in the battery community to understand defects and structural characterizations of cathode materials."
"The ability to measure the concentration of weakly scattering elements with the sensitivity of a tenth of a percent will also be useful for many other areas of research, such as measuring oxygen vacancies in superconducting materials or catalysts," added Khalifah.
With such accurate measurements of defect concentrations, the scientists could then study the relationship between defects and cathode material chemistry. Ultimately, they developed a ‘recipe’ for achieving any defect concentration, which, in the future, could guide scientists to synthesize cathodes from more affordable and environmentally friendly materials and then tune their defect concentrations for optimal battery performance.
The first hours of a lithium-ion battery's life largely determine just how well it will perform. In those moments, a set of molecules self-assembles into a component inside the battery that will affect the battery for years to come.
This component, known as the solid-electrolyte interphase (SEI), has the crucial job of blocking some particles while allowing others to pass, like a tavern bouncer rejecting undesirables while allowing in the glitterati. The SEI has proved an enigma to researchers who have studied it for decades. They have tapped multiple techniques to learn more, but never – until now – have they witnessed its creation at a molecular level. Knowing more about the SEI is a crucial step on the road to creating more energetic, longer-lasting and safer lithium-ion batteries.
The SEI is a very thin film of material that doesn't exist when a battery is first built. Only when the battery is charged for the very first time do molecules aggregate and electrochemically react to form the structure, which acts as a gateway, allowing lithium ions to pass back and forth between the anode and cathode. Crucially, the SEI forces electrons to take a detour, which keeps the battery operating and makes energy storage possible.
It's because of the SEI that we have lithium-ion batteries at all to power our cell phones, laptops and electric vehicles.
But scientists need to know more about this gateway structure. What factors separate the glitterati from the riffraff in a lithium-ion battery? What chemicals need to be included in the electrolyte, and in what concentrations, for the molecules to form themselves into the most useful SEI structures that don't continually sop up molecules from the electrolyte, hurting battery performance?
Scientists work with a variety of ingredients, predicting how they will combine to create the best SEI. But without knowing more about how the SEI is created, scientists are like chefs juggling ingredients, working with cookbooks that are only partially written. So an international team led by researchers at the US Department of Energy's Pacific Northwest National Laboratory (PNNL) and the US Army Research Laboratory set out to investigate just how the SEI is created, reporting their findings in a paper in Nature Nanotechnology.
To do this, the researchers took advantage of PNNL's patented technology. They used an energetic ion beam to tunnel into a just-forming SEI in an operating battery, sending some of the material airborne and capturing it for analysis while relying on surface tension to help contain the liquid electrolyte. Then the team analyzed the SEI material using a mass spectrometer.
This patented approach, known as in situ liquid secondary ion mass spectrometry (liquid SIMS), allowed the team to get an unprecedented look at the SEI as it formed and sidestep problems presented by a working lithium-ion battery. The technology was created by a team led by Zihua Zhu at PNNL, building on previous SIMS work by PNNL colleague Xiao-Ying Yu.
"Our technology gives us a solid scientific understanding of the molecular activity in this complex structure," said Zhu. "The findings could potentially help others tailor the chemistry of the electrolyte and electrodes to make better batteries."
The PNNL team connected with Kang Xu, a research fellow with the US Army Research Laboratory and an expert on electrolyte and the SEI, and together they tackled the question. They were able to confirm what researchers have long suspected – that the SEI is composed of two layers. But the team went much further, specifying the precise chemical make-up of each layer and determining the chemical steps that occur in a battery to bring about the structure.
They found that one layer of the structure, next to the anode, is thin but dense; this is the layer that repels electrons but allows lithium ions to pass through. The outer layer, right next to the electrolyte, is thicker and mediates interactions between the liquid and the rest of the SEI. The inner layer is a bit harder and the outer later is more liquidy, a little bit like the difference between undercooked and overcooked oatmeal.
One result of the study is a better understanding of the role of lithium fluoride in the electrolyte used in lithium-ion batteries. Several researchers, including Xu, have shown that batteries with SEIs richer in lithium fluoride perform better. The team showed how lithium fluoride becomes part of the inner layer of the SEI, and their findings offer clues about how to incorporate more fluorine into the structure.
"With this technique, you learn not only what molecules are present but also how they're structured," Wang says. "That's the beauty of this technology."
Aims and scope of the Special Issue:
An important and distinct theme in Additive Manufacturing concerns the rational design and optimization of materials used in powder-based production processes.
This Special Issue (VSI) is dedicated to recent progress in materials selection and elaboration for additive manufacturing (AM), in particular for such laser-based AM methods as powder bed fusion and directed energy deposition.
The VSI will cover recent advances in the synthesis of new metal and polymer powder materials for efficient laser-based 3D additive manufacturing through material formulation, additivation (including nano-additivation), and chemical modification of both newly developed and commercial powders.
Examples of topics to be covered in this VSI are:
- Specific adaptation of material parameters such as the absorption coefficients for infrared and visible lasers, glass transition and crystallization temperatures, as well as crystallization kinetics and enthalpy of powders to optimize laser-based additive manufacturing processes.
- Developments of (scalable) powder synthesis processes that aim at creating optimized crystallization-melting windows, e.g. by additive dispersion, providing shape and size-controlled powders, improved polymer chain mobility, kinetic control of melting and resolidification, and/or defined alloy recrystallisation.
- Significant extension of the property profiles of laser-based additive manufacturing parts by new and improved materials with e.g. adapted meltability, flowability, and wetting behavior.
- Improved understanding of the melting and sintering dynamics by in situ process monitoring, as well as analytical and theoretical methods.
- Improved understanding of the relationship between material structure and processability at different length scales via modelling and simulation.
All submitted papers must be clearly written in excellent English and contain only original work, which has not been published by or is currently under review for any other journal or conference. Papers must not exceed 25 pages (one-column, at least 11pt fonts) including figures, tables, and references. A detailed submission guideline is available as “Guide to Authors” at: http://www.journals.elsevier.com/materials-and-design/
All manuscripts and any supplementary material should be submitted through Elsevier Editorial System (EES). The authors must select as “VSI:Materials for AM” when they reach the “Article Type” step in the submission process. The EES website is located at: http://ees.elsevier.com/jmad/
All papers will be peer-reviewed by three independent reviewers. Requests for additional information should be addressed to the guest editors.
PD Dr. Bilal Gökce, University of Duisburg-Essen, Technical Chemistry and Center for NanoIntegration Duisburg-Essen CENIDE
Prof. Dr. Dongdong Gu, Nanjing University of Aeronautics and Astronautics, College of Materials Science and Technology
Prof. Dr. Michael Schmidt, University of Erlangen-Nuremberg, Department of Mechanical Engineering
Prof. Dr. Stephan Barcikowski, University of Duisburg-Essen, Technical Chemistry and Center for NanoIntegration Duisburg-Essen CENIDE
Composites UK has appointed Dr David Bailey as its new CEO.
Dr Bailey previously worked at Rolls-Royce and Alstom where he became head of technology in 2000 and led the company’s future technology program. He later joined the North West Aerospace Alliance (NWAA) in 2005 as director of operations and led its technology and supply chain development programs. He was appointed to the position of chief executive of NWAA in 2014, where he was responsible for one of the largest aerospace clusters in the world including organisations such as BAE Systems, Airbus, Rolls-Royce, Safran, MBDA Missile Systems, Kaman, Teledyne CML Composites and Sigmatex.
Dr Bailey was appointed to the board of the Aerospace Growth Partnership and was made a fellow of the Royal Aeronautical Society in 2017 for services to the North West’s aerospace industry.
‘I am hugely excited about this new opportunity to work with the members of Composites UK, helping them to improve their businesses, gain exposure to new customers and markets, and ultimately to do more business,’ said Dr Bailey. ‘I hope that my addition to the Composites UK team will help lift the capability of the organisation to the next level.’
‘As Composites UK looks to strengthen the value we add for members and take the association forward, the board felt it vital to have someone with David’s calibre to harness the Composites UK team’s strengths whilst focusing on further improving our membership proposition and supply chain opportunities across the growing composites sector in the UK,’ said Ben Wilson, chairman of Composites UK.
This story uses material from Composites UK, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Metal 3D printing company Aurora Labs has raised US$1.82 million from a private investor.
A placement of shares is reportedly being made to a nominee entity of Tjeerd Barthen, a Dutch entrepreneur who has founded a healthcare business. Barthen now invests globally in disruptive technologies with scalable opportunities, Aurora said.
“I have followed the growth of the sector for some time and quickly identified that Aurora Labs as a technological leader with the potential to revolutionise manufacturing,’ said Barthen. ‘I look forward to following the team on their journey.’
This story uses material from Aurora Labs, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
An international team of researchers has discovered that the hydrogen atoms in a metal hydride material are much more tightly spaced than had been predicted for decades – a feature that could possibly facilitate superconductivity at or near room temperature and pressure. Such a superconducting material, carrying electricity without any energy loss due to resistance, would revolutionize energy efficiency in a broad range of consumer and industrial applications.
The scientists conducted neutron scattering experiments at the US Department of Energy's Oak Ridge National Laboratory on samples of zirconium vanadium hydride at atmospheric pressure and temperatures ranging from -450°F (5K) to as high as -10F (250K) – much higher than the temperatures where superconductivity is expected to occur under these conditions. Their findings, reported in a paper in the Proceedings of the National Academy of Sciences, detail the first observations of such small hydrogen-hydrogen atomic distances in a metal hydride, as small as 1.6 angstroms, compared to the 2.1 angstrom distances predicted for these metals.
This interatomic arrangement is remarkably promising, since the hydrogen contained in metals affects their electronic properties. Other materials with similar hydrogen arrangements have been found to start superconducting, but only at very high pressures.
The research team included scientists from the Swiss Federal Laboratories for Materials Science and Technology (EMPA), the University of Zurich in Switzerland, the Polish Academy of Sciences, the University of Illinois at Chicago and ORNL.
"Some of the most promising 'high-temperature' superconductors, such as lanthanum decahydride, can start superconducting at about 8.0°F, but unfortunately also require enormous pressures as high as 22 million pounds per square inch, or nearly 1400 times the pressure exerted by water at the deepest part of Earth's deepest ocean," said Russell Hemley, professor and distinguished chair in the natural sciences at the University of Illinois at Chicago. "For decades, the 'holy grail' for scientists has been to find or make a material that superconducts at room temperature and atmospheric pressure, which would allow engineers to design it into conventional electrical systems and devices. We're hopeful that an inexpensive, stable metal like zirconium vanadium hydride can be tailored to provide just such a superconducting material."
Researchers had probed the hydrogen interactions in this well-studied metal hydride with high-resolution, inelastic neutron vibrational spectroscopy on the VISION beamline at ORNL's Spallation Neutron Source. However, the resulting spectral signal, including a prominent peak at around 50 millielectronvolts, did not agree with what the models predicted.
The breakthrough in understanding occurred after the team began working with the Oak Ridge Leadership Computing Facility (OLCF) to develop a strategy for evaluating the data. The OLCF at the time was home to Titan, one of the world's fastest supercomputers, a Cray XK7 system that operated at speeds up to 27 petaflops (27 quadrillion floating point operations per second).
"ORNL is the only place in the world that boasts both a world-leading neutron source and one of the world's fastest supercomputers," said Timmy Ramirez-Cuesta, team lead for ORNL's chemical spectroscopy team. "Combining the capabilities of these facilities allowed us to compile the neutron spectroscopy data and devise a way to calculate the origin of the anomalous signal we encountered. It took an ensemble of 3200 individual simulations, a massive task that occupied around 17% of Titan's immense processing capacity for nearly a week – something a conventional computer would have required 10 to 20 years to do."
These computer simulations, along with additional experiments ruling out alternative explanations, proved conclusively that the unexpected spectral intensity occurs only when distances between hydrogen atoms are closer than 2.0 angstroms, which had never been observed in a metal hydride at ambient pressure and temperature. The team's findings represent the first known exception to the Switendick criterion in a bimetallic alloy, a rule stating that for stable hydrides at ambient temperature and pressure the hydrogen-hydrogen distance is never less than 2.1 angstroms.
"An important question is whether or not the observed effect is limited specifically to zirconium vanadium hydride," said Andreas Borgschulte, group leader for hydrogen spectroscopy at Empa. "Our calculations for the material – when excluding the Switendick limit – were able to reproduce the peak, supporting the notion that in vanadium hydride, hydrogen-hydrogen pairs with distances below 2.1 angstroms do occur."
In future experiments, the researchers plan to add more hydrogen to zirconium vanadium hydride at various pressures to evaluate the material's potential for electrical conductivity. ORNL's Summit supercomputer – which at 200 petaflops is over seven times faster than Titan and since June 2018 has been No. 1 on the TOP500 List, a semiannual ranking of the world's fastest computing systems – could provide the additional computing power that will be required to analyze these new experiments.
The magnetic, conductive and optical properties of complex oxides make them key components of next-generation electronics for use in data storage, sensing, energy technologies, biomedical devices and many other applications.
Stacking ultrathin complex oxide single-crystal layers – each composed of geometrically arranged atoms – allows researchers to create new structures with hybrid properties and multiple functions. Now, using a new platform developed by researchers at the University of Wisconsin-Madison (UW-Madison) and the Massachusetts Institute of Technology (MIT), researchers will be able to make these stacked-crystal materials in virtually unlimited combinations. The researchers report their advance in a paper in Nature.
The researchers' new layering method overcomes a major challenge in conventional epitaxy – a process for depositing one material on top of another in an orderly way. In epitaxy, each new complex oxide layer must be closely compatible with the atomic structure of the underlying layer. It's sort of like stacking Lego blocks: the holes on the bottom of one block must align with the raised dots on top of the other. If there's a mismatch, the blocks won't fit together properly.
"The advantage of the conventional method is that you can grow a perfect single crystal on top of a substrate, but you have a limitation," explains Chang-Beom Eom, a UW-Madison professor of materials science and engineering and physics. "When you grow the next material, your structure has to be the same and your atomic spacing must be similar. That's a constraint, and beyond that constraint, it doesn't grow well."
A couple of years ago, a team of MIT researchers developed an alternate approach. Led by Jeehwan Kim, an associate professor in mechanical engineering and materials science and engineering at MIT, the group added an ultrathin intermediate layer of the two-dimensional carbon material known as graphene, then used epitaxy to grow a thin semiconducting material layer atop that.
Just one molecule thick, the graphene acts like a peel-away backing due to its weak bonding, allowing the researchers to remove the semiconductor layer from the graphene. What remained was a freestanding ultrathin sheet of semiconducting material.
Eom, an expert in complex oxide materials, says they are intriguing because they have a wide range of tunable properties – including multiple properties in one material – that many other materials do not. So it made sense to apply the peel-away technique to complex oxides, which are much more challenging to grow and integrate.
"If you have this kind of cut-and-paste growth and removal, combined with the different functionality of putting single-crystal oxide materials together, you have a tremendous possibility for making devices and doing science," says Eom, who connected with mechanical engineers at MIT during a sabbatical there in 2014.
The Eom and Kim research groups combined their expertise to create ultrathin complex oxide single-crystal layers, again using graphene as the peel-away intermediate. More importantly, however, they conquered a previously insurmountable obstacle – the difference in crystal structure – in integrating different complex oxide materials.
"Magnetic materials have one crystal structure, while piezoelectric materials have another," says Eom. "So you cannot grow them on top of each other. When you try to grow them, it just becomes messy. Now we can grow the layers separately, peel them off and integrate them."
In the study, the researchers demonstrated the efficacy of the technique using materials such as perovskite, spinel and garnet, among several others. The technique can also stack single complex oxide materials and semiconductors.
"This opens up the possibility for the study of new science, which has never been possible in the past because we could not grow it," says Eom. "Stacking these was impossible, but now it is possible to imagine infinite combinations of materials. Now we can put them together."
The advance also opens doors to new materials with functionalities that drive future technologies.
"This advance, which would have been impossible using conventional thin film growth techniques, clears the way for nearly limitless possibilities in materials design," says Evan Runnerstrom, program manager in materials design in the US Army Research Office, which funded part of the research. "The ability to create perfect interfaces while coupling disparate classes of complex materials may enable entirely new behaviors and tunable properties, which could potentially be leveraged for new Army capabilities in communications, reconfigurable sensors, low power electronics and quantum information science."
Wall Colmonoy says that the next session of its European modern furnace brazing school will take place from 6-8 October 2020 at Wall Colmonoy’s European headquarters in Pontardawe, Wales, UK.
The three-day seminar will include a facility tour, and covers brazing design, metallurgical aspects/brazing operation, brazing atmosphere and furnace equipment, brazing material selection and applications and quality control.
Atttendees will also have the opportunity to apply different forms of filler metal to supplied samples, have them vacuum brazed and discuss the outcomes.
Gurit has announced its sale of its Gurit Hungary Kft automotive business to Carbopress SpA, an Italian composite parts manufacturer.
In October 2019 Gurit said that it planned to close the business in summer 2020 following a divestment process which did not result in a transaction. Carbopress then expressed interest in acquiring the business which lead ultimately to the sale, Gurit said.
Gurit Hungary employs 144 staff members.
‘It is positive that we could find a solution for the employees and the customers,’ said Gurit CEO Rudolf Hadorn.
This story uses material from Gurit, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The US Department of Energy (DOE) plans to invest US$133 million in new advanced vehicle technologies research, including the development of lightweight carbon fiber reinforced plastic (CFRP) automotive parts.
The research topic areas also include batteries and electrification, advanced combustion engines and fuels, the reduction of platinum group metal content, materials technology and transportation and energy analysis.
Concept papers for this funding opportunity are due 21 February 2020 with full applications are due 14 April 2020, the DOE said. For more information and application requirements, go here.
This story uses material from the DOE, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Vyomesh Joshi will retire as president at CEO of 3D Systems.
Joshi joined 3D Systems in April 2016 and, according to the company, he has improved product quality and re-invigorated innovation across its portfolio of 3D printing hardware, materials, software and services.
‘On behalf of the board of directors, I want to personally thank VJ for his accomplishments at 3D Systems,’ said Charles McClure, chairman of the board of directors. ‘He is a pioneer and a visionary in digital manufacturing solutions and he has led this company through a vital phase.’
This story uses material from 3D Systems, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
As part of Elsevier’s ongoing efforts to promote gender diversity and advance gender equity using data and an evidence-based approach, we are preparing a new gender report—The Researcher Journey Through a Gender Lens—which will be released on March 5, 2020. Our latest report will further examine critical issues and performance in research through a gender lens and will include quantitative analyses into new areas and themes and incorporate a qualitative research component:
Research participation: Assessing gender diversity among researchers
Research footprint: Measuring the research footprint of both genders
Career progression & mobility: Assessing author continuity and mobility
Collaboration networks: Evaluating collaboration patterns and gender differences
Researcher perspectives: Perceptions about gender-related issues in academia
Our intention is to continue to share powerful data-driven insights with governments, funders, and institutions worldwide to inspire evidence-based policy and initiatives and inform further studies.
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Renewed investments in hydrogen fuel cell technologies and infrastructure by companies like Amazon, nations like China, and automakers like Toyota, Honda and Hyundai are sparking sales and fresh interest in the vast possibilities of polymer-electrolyte fuel cells. This fresh interest could revolutionize transportation and fill streets with vehicles whose only exhaust fumes are water vapor.
But that vision of clean, green cars and trucks is stymied by the need not only for massive infrastructure investment, but also for more efficient processes in the fuel cells themselves. Innovations that lower the cost of production – meaning lower prices – and that open the door to more vehicle segments, including performance cars, could drive greater adoption.
A team of researchers at the NYU Tandon School of Engineering and the Lawrence Berkeley National Laboratory has now created a novel polymeric material with the potential for solving both these problems. The researchers include Miguel Modestino, professor of chemical and biomolecular engineering at NYU Tandon, and Yoshi Okamoto, a professor of chemical engineering and director of the Polymer Research Institute at NYU Tandon.
Their hybrid material can deliver copious amounts of oxygen from the atmosphere to the cell's electrode reaction sites – generating more power – while also reducing the amount of expensive materials like platinum needed in fuel cells, potentially solving a major industry challenge. They describe this material in a paper in the Journal of the American Chemical Society.
Hydrogen fuel cells comprise an anode and a cathode separated by an electrolyte membrane. Electricity is produced as a result of hydrogen being split into electrons and protons at the anode. Ion-conducting polymers (ionomers) are used to transfer the protons to the cathode, where they combine with oxygen from the air to produce water, while the electrons are sent round an external circuit to generate electricity.
Current, commercially available ionomers are typically perfluorinated sulfonic acid (PFSA) polymers, which comprise a linear chainlike backbone composed of polytetrafluoroethylene (PTFE) matrix and pendant sulfonic-acid groups attached to the PTFE backbone that impart ion conductivity. While this complex combination, molecularly similar to Teflon, confers high mechanical strength, research shows that it suffers from low oxygen permeability, leading to significant energy losses in fuel cells.
The researchers solved several problems at once by swapping the linear PTFE polymer chains for a bulky fluorinated chain, creating a hybrid material that comprises an ion conducting polymer and a highly permeable matrix. This added more free volume to the matrix, vastly enhancing its ability to transport oxygen.
"We've created a novel copolymer – two components bound together. One part conducts ions, and the other is highly permeable to oxygen," explains Modestino. "Okamoto had been working on highly permeable polymers for gas separation processes. When I joined NYU Tandon, we realized that the polymers that he had developed could be adapted to improve fuel cells."
When several processes are going on at once, establishing cause-and-effect relationships can be difficult, as is the case for a class of high-temperature superconductors known as the cuprates. Discovered nearly 35 years ago, these copper-oxygen compounds can conduct electricity without resistance under certain conditions. They must be chemically modified (‘doped’) with additional atoms that introduce electrons or holes (electron vacancies) into the copper oxide layers and cooled to temperatures below 100K (-280°F) – significantly warmer temperatures than those needed for conventional superconductors.
But exactly how electrons overcome their mutual repulsion and pair up to flow freely in these materials remains one of the biggest questions in condensed matter physics. High-temperature superconductivity (HTS) is among many phenomena that occur due to strong interactions between electrons, making it difficult to determine exactly where it comes from.
That's why physicists at the US Department of Energy (DOE)’s Brookhaven National Laboratory studying a well-known cuprate with layers made of bismuth oxide, strontium oxide, calcium and copper oxide (BSCCO) decided to focus on the less complicated ‘overdoped’ side, doping the material so much that its superconductivity eventually disappeared. As they report in a paper in Nature Communications, this approach allowed them to identify that purely electronic interactions likely lead to HTS.
"Superconductivity in cuprates usually coexists with periodic arrangements of electric charge or spin and many other phenomena that can either compete with or aid superconductivity, complicating the picture," explained first author Tonica Valla, a physicist in the Electron Spectroscopy Group at Brookhaven Lab's Condensed Matter Physics and Materials Science Division. "But these phenomena weaken or completely vanish with overdoping, leaving nothing but superconductivity. Thus, this is the perfect region to study the origin of superconductivity. Our experiments have uncovered an interaction between electrons in BSCCO that correlates one-to-one with superconductivity. Superconductivity emerges exactly when this interaction first appears and becomes stronger as the interaction strengthens."
Only very recently has it become possible to overdope cuprate samples beyond the point where superconductivity vanishes. Previously, a bulk crystal of the material would be annealed (heated) in high-pressure oxygen gas to increase the concentration of oxygen (the dopant material). The new method – which Valla and other Brookhaven scientists first demonstrated about a year ago at OASIS, a new on-site instrument for sample preparation and characterization – uses ozone instead of oxygen to anneal cleaved samples. Cleaving refers to breaking the crystal in a vacuum to create perfectly flat and clean surfaces.
"The oxidation power of ozone, or its ability to accept electrons, is much stronger than that of molecular oxygen," explained co-author Ilya Drozdov, a physicist in the division's Oxide Molecular Beam Epitaxy (OMBE) Group. "This means we can bring more oxygen into the crystal to create more holes in the copper oxide planes, where superconductivity occurs. At OASIS, we can overdope surface layers of the material all the way to the non-superconducting region and study the resulting electronic excitations."
OASIS combines an OMBE system for growing oxide thin films with angle-resolved photoemission spectroscopy (ARPES) and spectroscopic imaging-scanning tunneling microscopy (SI-STM) instruments for studying the electronic structure of these films. Here, materials can be grown and studied using the same connected ultrahigh vacuum system, thereby avoiding oxidation and contamination by carbon dioxide, water and other molecules in the atmosphere. Because ARPES and SI-STM are extremely surface-sensitive techniques, pristine surfaces are critical to obtaining accurate measurements.
For this study, co-author Genda Gu, a physicist in the division's Neutron Scattering Group, grew bulk BSCCO crystals. Drozdov annealed the cleaved crystals in ozone in the OMBE chamber to increase the doping until the superconductivity was completely lost. The same sample was then annealed in vacuum in order to gradually reduce the doping and increase the transition temperature at which superconductivity emerges. Valla used ARPES to analyze the electronic structure of BSCCO across this doping-temperature phase diagram.
"ARPES gives you the most direct picture of the electronic structure of any material," said Valla. "Light excites electrons from a sample, and by measuring their energy and the angle at which they escape, you can recreate the energy and momentum of the electrons while they were still in the crystal."
In measuring this energy-versus-momentum relationship, Valla detected a kink (anomaly) in the electronic structure that follows the superconducting transition temperature. This kink becomes more pronounced and shifts to higher energies as the temperature increases and the superconductivity gets stronger, but disappears outside of the superconducting state.
On the basis of this information, Valla knew that the interaction creating the electron pairs required for superconductivity could not be electron-phonon coupling, as theorized for conventional superconductors. Under this theory, phonons, or vibrations of atoms in the crystal lattice, serve as an attractive force for otherwise repulsive electrons through the exchange of momentum and energy.
"Our result allowed us to rule out electron-phonon coupling because atoms in the lattice can vibrate and electrons can interact with those vibrations, regardless of whether the material is superconducting or not," said Valla. "If phonons were involved, we would expect to see the kink in both the superconducting and normal state, and the kink would not be changing with doping."
The team believes that something similar to electron-phonon coupling is going on in this case, but instead of phonons, another excitation gets exchanged between electrons. It appears that electrons are interacting through spin fluctuations, which are related to electrons themselves. Spin fluctuations are changes in electron spin, or the way that electrons point either up or down as tiny magnets.
Moreover, the scientists found that the energy of the kink is less than that of a characteristic energy at which a sharp peak (resonance) in the spin fluctuation spectrum appears. Their finding suggests that the onset of spin fluctuations (instead of the resonance peak) is responsible for the observed kink and may be the ‘glue’ that binds electrons into the pairs required for HTS.
Next, the team plans to collect additional evidence showing that spin fluctuations are related to superconductivity by obtaining SI-STM measurements. They will also perform similar experiments on another well-known cuprate, lanthanum strontium copper oxide (LSCO).
"For the first time, we are seeing something that strongly correlates with superconductivity," said Valla. "After all these years, we now have a better grasp of what may be causing superconductivity in not only BSCCO but also other cuprates."
A ‘hydrogen economy’ promises a low-carbon future but is hampered by the fact that hydrogen drastically reduces the strength of steel, which is needed for pipework and high-pressure storage. This phenomenon, which is called embrittlement, is thought to involve the accumulation of hydrogen at defects in steel.
“Whilst the phenomenon of hydrogen embrittlement has been known for more than a century, the exact origin and effective solutions are yet to be found,” explains Julie Cairney of the Australian Centre for Microscopy and Microanalysis at The University of Sydney.
Together with colleagues at CITIC Metal, the University of Science and Technology Beijing, Shanghai Jiao Tong University, and Microscopy Solutions, Cairney has found a way to determine exactly where hydrogen is trapped in steel, confirming the origins of the phenomenon and opening the way to the design of embrittlement-resistant steels [Chen et al., Science367 (2020) 171 https://science.sciencemag.org/content/367/6474/171.abstract].
“Our work focused on observing the behavior of hydrogen in steels at the atomic scale,” say Cairney and Yi-Sheng Chen, first author of the study. “By determining precisely which microstructural features within steels interact with hydrogen and are responsible for fracture initiation, we sought to provide a more sophisticated insight into this problem.”
Hydrogen is thought to accumulate at defects and grain boundaries, leading to intergranular failure or enhanced dislocation activity, which allows cracks to grow and propagate. To determine whether this theory holds true in practice, the team turned to atom probe tomography (APT). The technique ablates the surface of a sample, detecting the atoms that are driven off, to generate a three-dimensional map of the positions of atoms within the structure to near atomic resolution.
“Coupled with a custom-developed sample preparation technique, we set out to understand the specific mechanisms that lead to hydrogen embrittlement of steel, as well as to highlight a tangible pathway to solve this problem,” says Cairney.
The researchers used an isotope of hydrogen, deuterium, to give a more unambiguous signal and a customized cryogenic sample-transfer so that the samples can be cooled to very low temperatures very quickly.
“This allows us to ‘freeze’ the hydrogen in place prior to APT observation, ensuring that the measured location is a true reflection of the hydrogen location without significant movement due to diffusion,” explain Cairney and Chen.
Not only did APT confirm that hydrogen accumulates at dislocations and grain boundaries, it also revealed that hydrogen collects at the surface of carbide precipitates present in the steel matrix.
“This exciting result demonstrates that carbide precipitates can be utilized to trap damaging hydrogen, providing a clear design pathway to create new materials that are highly resistant to hydrogen embrittlement,” says Cairney.
The research was funded by the Australian Research Council and CITIC Metal, and conducted using instruments and technical assistance provided by Microscopy Australia at the Australian Centre for Microscopy & Microanalysis at the University of Sydney, a facility funded by the University, and New South Wales and Australian Federal Governments.
Fundamental research in condensed matter physics has driven tremendous advances in modern electronic capabilities. Transistors, optical fiber, LEDs, magnetic storage media, plasma displays, semiconductors, superconductors – the list of technologies born of fundamental research in condensed matter physics is staggering. Scientists working in this field continue to explore and discover surprising novel phenomena that hold promise for tomorrow's technological advances.
An important line of inquiry in this field involves topology – a mathematical framework for describing surface states that remain stable even when the material is deformed by stretching or twisting. The inherent stability of topological surface states has implications for a range of applications in electronics and spintronics.
Now, a team of researchers from the US and China has discovered an exotic new form of topological state in a large class of three-dimensional (3D) semi-metallic crystals called Dirac semimetals. The researchers developed extensive mathematical machinery to bridge the gap between theoretical models containing forms of ‘higher-order’ topology (topology that manifests only at the boundary of a boundary) and the physical behavior of electrons in real materials. They report their findings in a paper in Nature Communications.
Over the past decade, Dirac and Weyl fermions have been predicted and experimentally confirmed in a number of solid-state materials, most notably in crystalline tantalum arsenide (TaAs), the first topological Weyl fermion semimetal to be discovered. Several researchers observed that TaAs exhibits two-dimensional (2D) topological surface states known as ‘Fermi arcs’. But similar phenomena observed in Dirac fermion semimetals have eluded understanding, until now.
In the context of semimetals, a Fermi arc is a surface state that behaves like one-half of a 2D metal; the other half is found on a different surface.
"This is not something that's possible in a purely 2D system, and can only happen as a function of the topological nature of a crystal," says team member Barry Bradlyn, professor of physics at the University of Illinois at Urbana-Champaign. "In this work, we found that the Fermi arcs are confined to the 1D hinges in Dirac semimetals."
In earlier work, certain members of this research team, including Xi Dai from Hong Kong University of Science and Technology and Andrei Bernevig from Princeton University, experimentally demonstrated that the 2D surfaces of Weyl semimetals must host Fermi arcs, regardless of the details of the surface. This is a topological consequence of the Weyl points (fermions) present deep within the bulk of the crystal.
"Weyl semimetals have layers like onions," notes Dai. "It's remarkable that you can keep peeling the surface of TaAs, but the arcs are always there."
Researchers have also observed arc-like surface states in Dirac semimetals, but attempts to develop a similar mathematical relationship between such surface states and Dirac fermions in the bulk of the material have been unsuccessful. It became clear that the Dirac surface states arise from a different, unrelated mechanism, and it was concluded the Dirac surface states were not topologically protected.
In the current study, the researchers were surprised to encounter Dirac fermions that appeared to exhibit topologically protected surface states, contradicting this conclusion. Working on models of Dirac semimetals derived from topological quadrupole insulators – higher-order topological systems recently discovered by Bernevig in collaboration with Taylor Hughes from the University of Illinois – they found that this new class of materials exhibits robust, conducting electronic states in 1D, or two fewer dimensions than the bulk 3D Dirac points.
Initially confounded by the mechanism through which these ‘hinge’ states appeared, the researchers worked to develop an extensive, exactly solvable model for the bound states of topological quadrupoles and Dirac semimetals. They found that, in Dirac semimetals, Fermi arcs are generated by a different mechanism than the arcs in Weyl semimetals.
"In addition to settling the decades-old problem of whether condensed matter Dirac fermions have topological surface states," says team member Benjamin Wieder, a postdoctoral researcher at Princeton University, "we demonstrated that Dirac semimetals represent one of the first-solid state materials hosting signatures of topological quadrupoles."
"Unlike Weyl semimetals, whose surface states are cousins of the surfaces of topological insulators, we have shown that Dirac semimetals can host surface states that are cousins of the corner states of higher-order topological insulators," says Bradlyn.
The team discovered that almost all condensed matter Dirac semimetals should exhibit hinge states. "Our work provides a physically observable signature of the topological nature of Dirac fermions, which was previously ambiguous," notes team member Jennifer Cano, a professor of physics at the State University of New York at Stony Brook.
"It's clear that numerous previously studied Dirac semimetals actually do have topological boundary states, if one looks in the right place," Bradlyn adds.
Through first-principles calculations, the researchers theoretically demonstrated the existence of overlooked hinge states on the edges of known Dirac semimetals, including the prototypical material, cadmium arsenide (Cd3As2).
"With an amazing team combining skills from theoretical physics, first-principles calculations and chemistry, we were able to demonstrate the connection between higher-order topology in two dimensions and Dirac semimetals in three dimensions, for the first time," says Bernevig.
The team's findings have implications for the development of new technologies, including in spintronics, because the hinge states can be converted into edge states whose direction of propagation is tied to their spin, much like the edge states of a 2D topological insulator. Additionally, nanorods of higher-order topological semimetals could realize topological superconductivity on their surfaces when placed in close proximity to conventional superconductors. This could potentially realize multiple Majorana fermions, which have been proposed as ingredients for achieving fault-tolerant quantum computation.
Physicists at the University of Groningen in the Netherlands have visualized hydrogen at the interface between titanium and titanium hydride with a transmission electron microscope (TEM). Using a new technique, they succeeded in visualizing both the metal and the hydrogen atoms in a single image, allowing them to test different theoretical models that describe the interface structure. The physicists report their findings in a paper in Science Advances.
To understand the properties of materials, it is often vital to observe their atomic-scale structure. But while scientists have visualized atoms with a TEM, no one has so far succeeded in producing proper images of both heavy atoms and the lightest one of all (hydrogen).
This is exactly what Bart Kooi, professor of nanostructured materials at the University of Groningen, and his colleagues have now done. Using a new TEM with advanced capabilities, they were able to produce images of both titanium atoms and hydrogen atoms at the interface between titanium and titanium hydride.
The resulting pictures show how columns of hydrogen atoms fill spaces between the titanium atoms, distorting the crystal structure. The hydrogen atoms occupy half of the spaces, which was originally predicted years ago. “In the 1980s, three different models were proposed for the position of hydrogen at the metal/metal hydride interface,” says Kooi. “We were now able to see for ourselves which model was correct.”
To create the metal/metal hydride interface, Kooi and his colleagues started out with titanium crystals, which they infused with atomic hydrogen. The hydrogen atoms penetrated the titanium in very thin wedges, forming tiny metal hydride crystals.
“In these wedges, the numbers of hydrogen and titanium atoms are the same,” Kooi explains. “The penetration of hydrogen creates a high pressure inside the crystal. The very thin hydride plates cause hydrogen embrittlement in metals, for example inside nuclear reactors.” The pressure at the interface prevents the hydrogen from escaping.
Producing images of the heavy titanium atoms and the light hydrogen atoms at the interface was quite a challenge. First, the sample was loaded with hydrogen and then viewed at a specific orientation along the interface. This was achieved by using an ion beam to cut properly aligned crystals from titanium and then to make the samples thinner – to a thickness of no more than 50nm.
The physicists were able to visualize the titanium atoms and hydrogen atoms at the same time thanks to several innovations included in the novel TEM. Heavy atoms can be visualized by the way they scatter the electrons in the microscope beam, with the scattered electrons preferably detected using high-angle detectors.
“Hydrogen is too light to cause this scattering, so for these atoms, we have to rely on constructing the image from low-angle scattering, which includes electron waves,” says Kooi. However, the material being studied causes interference in these electron waves, which has so far made identifying hydrogen atoms almost impossible.
Kooi and his colleagues detected the electron waves using a low-angle bright-field detector, which comprises a circular bright-field detector divided into four segments. By analyzing differences in the wavefronts detected in opposing segments and looking at the changes that occur when the scanning beam crosses the material, the physicists were able to filter out the interferences and visualize the very light hydrogen atoms.
“The first requirement is to have a microscope that can scan with an electron beam that is smaller than the distance between the atoms. It is subsequently the combination of the segmented bright-field detector and the analytical software that makes visualization possible,” explains Kooi, who worked in close collaboration with scientists from Thermo Fisher Scientific, the company that manufactured the TEM.
Kooi's group added various noise filters to the TEM’s software and tested them. They also performed extensive computer simulations, against which they compared the experimental images.
In this way, they were able to investigate the interaction between hydrogen and the metal, which is useful knowledge for the study of materials capable of storing hydrogen. “Metal hydrides can store more hydrogen per volume than liquid hydrogen,” says Kooi.
Furthermore, the techniques used to visualize the hydrogen could also be applied to other light atoms, such as oxygen, nitrogen or boron, which are important in many nanomaterials. “Being able to see light atoms next to heavy ones opens up all kinds of opportunities,” he adds.
Umicore says that its 2020 revenues grew by 3% to €3.4 billion, with recurring EBITDA increased 5% to €753 million and recurring EBIT was €509 million. Revenues and recurring EBIT in the second half posted strong sequential growth and were up 6% and 12% respectively, the company said.
According to the company, the performance of its Energy and Surface Technologies businesses was well below the record levels of last year, due to a temporary market slowdown, particularly in the electrical vehicle (EV) segment in China, as well as the impact from a depressed cobalt price and the inflow of cheaper cobalt units unethically sourced from artisanal mining.
A strong performance and year-on-year growth in Recycling were driven by higher metal prices and a favorable supply environment, Umicore said.
‘Umicore expects to grow revenues and earnings in 2020 despite a deterioration in the global macro-economic environment since then, particularly in the automotive sector,’ said a company in a press release. ‘This growth outlook assumes that the recent coronavirus outbreak will not result in a protracted or material effect on the economy in 2020.
[…] Despite the expectation of subdued EV sales in China, Energy and Surface Technologies anticipates benefitting from higher sales of cathode materials for EVs in 2020, as well as the consolidation of the recently acquired activities in Kokkola, Finland.’
‘I am proud of our performance in 2019 and pleased to confirm the growth outlook for 2020 despite the adverse market trends that developed in the course of 2019,’ said Marc Grynberg, CEO.
This story uses material from Umicore, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The Powder Coating Institute (PCI) has named its 2020 board of directors and executive officers.
The 2020 president has been named Suresh Patel, sales director at Chemetall Mexico, replacing John Sudges, sales manager, Midwest Finishing Systems, with VP Sue Ivancic, value added services coordinator, Nordson Corporation. Secretary/treasurer is Chris Merritt, general manager, Gema USA.
Marty Korecky, business specialist – business systems at AkzoNobel Powder Coatings was elected to the board.
In addition to the new board member and officers, serving on the board of directors for 2020 are: John Cole, president, Parker Ionics, Ron Cudzilo, regional sales manager, George Koch Sons, Rick Gehman, president, Keystone Koatings, Tom Whalen, vice president sales and marketing, TCI Powder Coatings, Shelley Verdun, business manager PPG powder coatings, PPG Industries, Paul West, director of marketing, Sun Polymers International, and PCI Legal Counsel, David Goch, partner, Webster, Chamberlain and Bean.
This story uses material from the PCI, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Kordsa subsidiary Axiom Materials has invested in a new 3500 m2 facility for the development, analysis, and production of ceramic matrix composite materials.
According to the company, the High-Temperature Composite Center (HTCC) will include specialized prepreg coaters to produce both unidirectional and woven products for high-temperature composite applications. It will also feature R&D labs, an ISO Class 8 cleanroom for prepreg layup, and autoclave curing and sintering capabilities to produce developmental and certification panels.
‘Last year, we had expanded our reinforcement areas and competencies with the acquisition of fabric development, textile products and advanced honeycomb Technologies,’ said Murat Arcan, COO at Kordsa. ‘The acquisition of Axiom Materials is a major step in our growth strategy as we pursue advanced composite technologies for aerospace as well as next-generation industrial and transportation applications. Axiom Materials reshapes the composite industry with their R&D activities, especially in the area of high-temperature composites.’
‘While oxide-oxide and related high-temperature composites have traditionally been deployed for specific requirements such as thermal resistance, weight, low creep, low corrosivity, or low dielectric properties, application engineers are now recognizing the complete value they provide, including greenhouse gas reduction, improved fuel efficiencies, noise reduction, and resistance to long-term environmental degradation,’ said Johnny Lincoln, president of Axiom Materials.
This story uses material from Kordsawith editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Prepreg specialist Composites Evolution has appointed Scott Macdonald as sales manager.
According to the company, Macdonald has over 10 years’ experience in the composites industry, working including tooling, component materials, resins, honeycombs and process materials along with the vacuum bagged processing of composites in traditional consumables and also in silicone reusable systems.
This story uses material from Composites Evolution, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Nanoengineers at the University of California (UC) San Diego have developed a computer-based method that could make it less labor-intensive to determine the crystal structures of various materials and molecules, including alloys, proteins and pharmaceuticals.
Their method uses a machine learning algorithm, similar to the type used in facial recognition and self-driving cars, to independently analyze electron backscatter diffraction (EBSD) patterns produced by a scanning electron microscope (SEM), and do so with at least 95% accuracy. The nanoengineers, led by UC San Diego nanoengineering professor Kenneth Vecchio and his PhD student Kevin Kaufmann, report their work in a paper in Science.
Compared to other electron diffraction techniques, such as those used with transmission electron microscopy (TEM), SEM-based EBSD can be performed on large samples and analyzed at multiple length scales. This provides local sub-micron information mapped to centimeter scales. For example, a modern EBSD system allows the determination of fine-scale grain structures, crystal orientations, relative residual stress or strain, and other information in a single scan of the sample.
The drawback of commercial EBSD systems is the software's inability to determine the atomic structure of the crystalline lattices within the material being analyzed. This means a user of commercial software must select up to five crystal structures presumed to be in the sample. The software then attempts to find probable matches to these candidate structures in the diffraction pattern.
Unfortunately, the complex nature of the diffraction pattern means the software often finds false matches in the user-selected list. As a result, the accuracy of existing software's determination of the lattice type is dependent on the operator's experience and prior knowledge of the sample.
The method that Vecchio's team developed does all this autonomously, as the deep neural network independently analyzes each diffraction pattern to determine the crystal lattice, out of all possible lattice structure types, with a high degree of accuracy (greater than 95%). According to the researchers, a wide range of research areas, including pharmacology, structural biology and geology, could benefit from using similar automated algorithms to reduce the amount of time required for identifying crystal structures.
Graduates and students of WUST and Poznań University of Technology have developed an application that will allow quick reporting and managing failures. It can be used not only by hotel and apartment managers but also by service companies.
Output for the domestic market declined by 7.0% during the same period, with 2,408 fewer UK-built CVs produced, the SMMT said, while exports also fell -8.4% to 46,110 units.
However, in December, new model CV output rose 8.7%, with manufacturing for export rising by almost a third (30.5%).
’2019 was a turbulent year for British commercial vehicle production, with key model changeovers and some regulatory issues contributing to the falling output,’ said Mike Hawes, SMMT chief executive. ‘With model changeovers now complete, we expect to see CV output bounce back this year, however, this is reliant on political and economic stability that supports domestic demand. Given exports still account for the majority of UK output, with nine in ten vehicles shipped overseas destined for the EU, we need a trading relationship with Europe that protects this vital pillar of UK manufacturing, and this means a tariff-free trade agreement that puts automotive at its center.’
This story uses material from the SMMT, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
America Makes has appointed Alexander Steeb as its new operations director and Andrew Resnick as its new communications and public affairs director.
According to the organization, the appointments will help it promote additive manufacturing (AM).
Before joining America Makes, Steeb served as the vice president of operations for Altronic LLC a manufacturer of ignition and control systems for industrial engines, and global head of controlling for hydraulic company Hoerbiger. Resnick previously served as a MD at public affairs firm Five Corners Strategies and as director of public affairs for the Corn Refiners Association (CRA.
‘We are pleased to welcome Alexander and Andrew to the America Makes leadership team,’ said America Makes Executive Director John Wilczynski. ‘Both Alexander and Andrew will share the same goal of continuing to grow America Makes as the recognized national thought leader in AM through different, yet equally important, capacities.’
This story uses material from America Makes, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Conbility has released a new 2D tape placement machine, a table-based tape machine which can reportedly produce fully consolidated tailored blanks using laser heating.
The 5 m3 x 2.5 m3 x 2.5 m3 machine has been installed in Conbility´s new technical center based in Germany and available for evaluations and job-shop manufacturing of laminates.
Conbility says that tailored blanks made of thermoplastic tapes can reduce production costs for continuous fiber reinforced thermoplastics. Flat blanks are produced by the assembly of tape cuts and then the blanks thermoformed, and to achieve a repeatable forming and a fast, homogeneous heating of the blanks, a consolidation of the single layers of the blanks is necessary. According to the company, the new 2D-placement machine uses laser radiation to directly weld the tapes together so that the blanks can be directly processed further in classical tamp forming or in one-shot forming/overmolding processes.
This story uses material from Conbility, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
When chemists or engineers want to make a new type of material, they head to the laboratory and start ‘cooking’. Much like trying to improve upon a food recipe, this process involves trying new chemical ingredients or adjusting cooking times and temperatures. But what if instead of relying on a time-consuming process without guarantees of success, scientists could simply ‘snap’ different chemical ‘pieces’ together to make something new?
In a paper in the Journal of the American Chemical Society, researchers from the University of Pennsylvania, the University of Nebraska-Lincoln (UNL), the Colorado School of Mines and the Harbin Institute of Technology in China report a new approach to synthesizing organic ‘Legos’ that can be easily connected to make new materials. This framework creates structures that are lightweight, porous, quick to synthesize and easily modified to create new materials with unique properties.
The study focuses on a class of materials known as covalent organic frameworks (COFs), which are two-dimensional (2D) and three-dimensional (3D) organic solids held together with strong, covalent bonds. COFs have crystalline structures made of light elements like carbon, nitrogen and oxygen, making them lightweight and durable. Like individual Lego pieces, individual chemical building blocks can be assembled in defined ways to form COFs that can be planned in great detail, instead of putting components into a mixture and seeing what comes out.
The specific building blocks used in this study are known as porphyrins, a family of organic structures found in proteins like hemoglobin and chlorophyll. These structures include a metal atom at their center, and researchers would like to use this reactive atom to create COF materials with enhanced properties.
Despite the wide number of potential applications, ranging from hydrogen storage to carbon capture, these types of COFs have practical limitations. Making COFs is a slow process, and it can take several days to create just a gram of material. Existing methods are also only able to synthesize COFs in powder form, making them much harder to process or to transfer onto other materials.
But by taking advantage of the UNL team’s expertise in electropolymerization, a method for controlling polymer synthesis on a substrate that conducts electricity, the researchers found they could use electricity to create thin films of COFs. The resulting material, comprising 2D sheets stacked in multiple layers, is lightweight and heat tolerant and takes hours to synthesize instead of days.
"This method is fast, simple and cheap, and you enable deposition of a thin film onto a variety of conductive substrates," says Elham Tavakoli, who led the study along with fellow UNL graduate student Shayan Kaviani under the supervision of assistant professor Siamak Nejati. "Through this approach, we can avoid the common challenges with the COF synthesis through conventional solvothermal method."
After studying the structure of the deposited COFs in more detail, however, the researchers found something they couldn't explain: the interlayer distances, or how far the 2D sheets were from one another, were much larger than expected. The experimentalists then turned to theoretical chemists at the University of Pennsylvania to determine what was going on.
After trying to create a theoretical model that would accurately describe the COF's structure, University of Pennsylvania postdoc Arvin Kakekhani realized that something must be missing from the model. So he studied the list of all the chemicals used in the COF's synthesis process to see if any of the additives might explain the unexpected results. He and his colleagues were surprised to find that a ‘spectator’ molecule, pyridine, which they thought only provided the electrochemical environment necessary for the reaction to occur, was an essential component of the COF's structure.
The idea that a molecule like pyridine, a small organic molecule with a simple ring structure, can help crystals to form is not a new concept in chemistry, but it wasn't thought to be important for COF structure before this study. Now, the researchers have a better understanding of how this spectator fits perfectly within the 2D layers and provides the support needed for the COFs to form a crystal structure. "These smaller pyridine molecules actually go into the material and become part of the crystal," says Kakekhani.
This new approach is now a starting point for creating numerous types of materials. By changing the reaction conditions and the types of COF building blocks, and by replacing the pyridine with another small molecule, the opportunities for creating new materials with unique properties are endless.
"COFs are not that old, so they have lots of undiscovered points," says Tavakoli. "I'm looking forward to finding more of these myths in this field."
In the near term, the researchers hope to tune the catalytic properties of synthesized COFs and to develop site-isolated catalysts. "Our current COF has chemical reactivity, but that can be greatly heightened through small modifications," says Andrew Rappe, professor of chemistry in the University of Pennsylvania's School of Arts and Sciences. "Our team can take one platform and make many materials with different functionalities, all based on the work reported here."
"We foresee that the developed platform will allow us to design and realize many functional interfaces not yet explored. A wide range of applications, such as high selectivity separation and efficient catalysis, can be envisioned for these systems," says Nejati.
Kakekhani emphasizes that the work also showcases the importance of having theorists and experimentalists work in close collaboration. "It was not only about having something that matches their data," he says, "but about generating some insight that can make these materials better. It takes two to tango, and if we find a way to use each other's insight, there is room for discovering new things."
A multidisciplinary team of researchers has developed a new class of protein-based filtration membranes that are faster to produce and higher performing than current technology. These membranes could reduce energy consumption, operational costs and production time in industrial separations, making them useful for a variety of applications, from water purification to small-molecule separations to contaminant-removal processes.
Led by Manish Kumar, associate professor in the Cockrell School of Engineering at The University of Texas at Austin (UT Austin), the research team reports the new high-performance membranes in a paper in Nature Materials.
These filtration membranes possess a higher density of pores than found in commercial membranes and can be produced much faster – in two hours, versus the several-day process currently required. Until now, integrating protein-based membranes into the technology used for industrial separations has been challenging because of the amount of time needed to create these membranes and the low density of protein pores in them.
This study brought together engineers, physicists, biologists and chemists from UT Austin, Penn State, the University of Kentucky, the University of Notre Dame and the company Applied Biomimetic. It presents the first end-to-end synthesis of a true protein-based separation membrane with pores between 0.5nm and 1.5nm in size.
The membranes created by the researchers are biomimetic, meaning they mimic systems or elements of nature, specifically those that naturally occur in cell membranes for transporting water and nutrients. The high-density packing of protein channels into polymer sheets forms protein pores within the membrane, similar to those seen in human eye lenses, but within a nonbiological polymer environment.
The researchers fabricated three different biomimetic membranes, demonstrating a sharp, unique and tunable selectivity with three different pore sizes formed by the protein channels. The methods described can be adapted by inserting protein channels of different pore sizes or chemistries into polymer matrices to conduct specifically designed separations.
"In the past, attempts to make biomimetic membranes fell far short of the promise of these materials, demonstrating only two to three times improvement in productivity," said Yu-Ming Tu, a UT Austin chemical engineering doctoral student and lead on the study. "Our work shows a surprising 20 to 1000 times improvement in productivity over the commercial membranes. At the same time, we can achieve similar or better separation of small molecules, like sugars and amino acids, from larger molecules, like antibiotics, proteins and viruses."
This high productivity was made possible by the very high density of pore proteins in the membrane. Approximately 45 trillion proteins can fit onto a membrane the size of a US quarter, although the membranes created were actually 10–20 times larger in area. This makes the pore density 10 to 100 times higher than in conventional filtration membranes with similar nano-sized pores. Additionally, all the pores in these membranes are exactly the same size and shape, allowing them to better retain molecules of desired sizes.
"This is the first time that the promise of biomimetic membranes involving membrane proteins has been translated from the molecular scale to high performance at the membrane scale," Kumar said. "For so long, engineers and scientists have been trying to find solutions to problems only to find out nature has already done it and done it better. The next steps are to see if we can fabricate even larger membranes and to test whether they can be packaged into flat sheet and spiral-wound-type modules like the ones common in industry."
The MPIF says that Dr Randall German has been selected to receive the Kempton H Roll Powder Metallurgy (PM) Lifetime Achievement Award.
German is the founder of German Materials Technology and has developed the research of net-shape fabrication of engineering materials via sintering techniques as used in PM, cemented carbides, and ceramics. He has also promoted the growth of PM technology during his 50-year career through his involvement in 12 start-up companies, supervising well over a hundred graduate and post-doctoral students, and prolific PM industry publications. German has also been an active member in APMI International, the American Society for Metals, and the American Ceramics Society. He received the MPIF Distinguished Service to PM Award in 1993 and was one of the first APMI members to be awarded the prestigious APMI International Fellow Award in 1998.
The Lifetime Achievement Award, named after Kempton H Roll, founding executive director of MPIF, was established in 2007 in order to recognize individuals with outstanding accomplishments and achievements in the field of PM and related technologies.
This story uses material from the MPIF, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
The Chemical Coaters Association International (CCAI) has issued a call for papers for its Fabtech conference, taking place from 18–20 November 2020 in Las Vegas, NV, USA.
The metal forming, fabricating, welding and finishing event also covers additive manufacturing, automation, cutting, finishing, forming and fabricating, laser, lean principles and lean tools, management, marketing, metal fabrication tools, smart manufacturing, stamping, tube & pipe and workforce development, the CCAI said.
The deadline for submission is 3 April 2020. Go here to submit an abstract.
This story uses material from CCAI, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.