In a surprising discovery, an international team of researchers, led by scientists at the University of Minnesota, found that deformations in a quantum material can cause imperfections in its crystal structure that can actually improve the material’s superconducting and electrical properties.
These ground-breaking findings, reported in a paper in Nature Materials, could provide new insights into the development of the next generation of quantum-based computing and electronic devices.
“Quantum materials have unusual magnetic and electrical properties that, if understood and controlled, could revolutionize virtually every aspect of society and enable highly energy-efficient electrical systems and faster, more accurate electronic devices,” said study co-author Martin Greven, a professor in the University of Minnesota’s School of Physics and Astronomy and director of its Center for Quantum Materials. “The ability to tune and modify the properties of quantum materials is pivotal to advances in both fundamental research and modern technology.”
Elastic deformation of materials occurs when the material is subjected to stress but returns to its original shape once the stress is removed. In contrast, plastic deformation is the non-reversible change of a material’s shape in response to an applied stress – or more simply, the act of squeezing or stretching a material until it loses its shape. Plastic deformation has been used by blacksmiths and engineers for thousands of years. An example of a material with a large plastic deformation range is wet chewing gum, which can be stretched to dozens of times its original length.
While elastic deformation has been extensively used to study and manipulate quantum materials, the effects of plastic deformation have not yet been explored. In fact, conventional wisdom would lead scientists to believe that 'squeezing' or 'stretching' quantum materials may remove their most intriguing properties.
In this pioneering study, the researchers used plastic deformation to create extended periodic defect structures in a prominent quantum material known as strontium titanate (SrTiO3). These defect structures induced changes in the material's electrical properties and boosted its superconductivity.
“We were quite surprised with the results,” Greven said. “We went into this thinking that our techniques would really mess up the material. We would have never guessed that these imperfections would actually improve the materials’ superconducting properties, which means that, at low enough temperatures, it could carry electricity without any energy waste.”
According to Greven, this study demonstrates the great promise of plastic deformation as a tool to manipulate and create new quantum materials. It could lead to novel electronic properties, including materials with high potential for applications in technology. He also said the study highlights the power of state-of-the-art neutron and X-ray scattering probes for deciphering the complex structures of quantum materials, and of a scientific approach that combines experiment and theory.
“Scientists can now use these techniques and tools to study thousands of other materials,” Greven said. “I expect that we will discover all kinds of new phenomena along the way.”
In what should be a win-win-win for the environment, a process developed by researchers at Rice University to extract valuable metals from electronic waste would also use up to 500 times less energy than current lab methods and produce a by-product clean enough for use on agricultural land.
The Rice researchers adapted the flash Joule heating method, which they introduced last year to produce graphene from carbon sources like waste food and plastic, to recover rhodium, palladium, gold and silver for reuse. In a paper on this work in Nature Communications, the researchers, led by chemist James Tour, report that highly toxic heavy metals including chromium, arsenic, cadmium, mercury and lead can also be removed from the flashed materials, leaving a by-product with minimal metal content.
Instantly heating the electronic waste to 3400K (5660°F) with a jolt of electricity vaporizes the precious metals, and the gases are vented away for separation, storage or disposal. Tour said that with more than 40 million tons of e-waste produced globally every year, there is plenty of potential for such 'urban mining'.
“Here, the largest growing source of waste becomes a treasure,” Tour said. “This will curtail the need to go all over the world to mine from ores in remote and dangerous places, stripping the Earth’s surface and using gobs of water resources. The treasure is in our dumpsters.”
He noted that an increasingly rapid turnover of personal devices like cell phones has driven the worldwide rise of electronic waste, with only about 20% of landfill waste currently being recycled. “We found a way to get the precious metals back and turn e-waste into a sustainable resource,” he said. “The toxic metals can be removed to spare the environment.”
Tour and his team found that flashing e-waste requires some preparation. Guided by lead author and Rice postdoctoral research associate Bing Deng, the researchers first powdered the circuit boards they used to test the process, and then added halides like Teflon or table salt and a dash of carbon black to improve the recovery yield.
Once flashed, the process relies on 'evaporative separation' of the metal vapors. These vapors are transported from the flash chamber under vacuum to another vessel, a cold trap, where they condense into their constituent metals. “The reclaimed metal mixtures in the trap can be further purified to individual metals by well-established refining methods,” Deng said.
The researchers reported that one flash Joule reaction reduced the concentration of lead in the remaining char to below 0.05 parts per million, the level deemed safe for agricultural soils. Levels of arsenic, mercury and chromium were all further reduced by increasing the number of flashes. “Since each flash takes less than a second, this is easy to do,” Tour said.
The scalable Rice process consumes about 939 kilowatt-hours per ton of material processed – 80 times less energy than commercial smelting furnaces and 500 times less than laboratory tube furnaces, according to the researchers. It also eliminates the lengthy purification required by smelting and leaching processes.
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.
The MPIF says that the proceedings of its PowderMet2021, AMPM2021 and Tungsten, Refractory & Hardmaterials 2021 conferences are now available for purchase. All three conferences took place from 20- 23 June 2021 in Orlando, Florida and online.
Advances in Powder Metallurgy & Particulate Materials 2021 contains the proceedings of PowderMet2021 and contains 46 technical papers, while Advances in Additive Manufacturing With Powder Metallurgy 2021 covers the additive manufacturing (AM) event and contains 54 technical papers.
Advances in Tungsten, Refractory & Hardmaterials 2021 features the proceedings of Tungsten, Refractory & Hardmaterials 2021 sponsored by the Metal Powder Industries Federation in cooperation with the Refractory Metals Association and APMI International and contains 18 technical papers.
Harper International has launched a new lab-scale rotary furnace which can process materials on a smaller scale than that possible with production-scale thermal process equipment.
According to the company, the furnace has improved temperature uniformity for batch or continuous processing of advanced materials including granular, powder, or particulate aggregates at operating temperatures up to 1200°C. Harper also offers options for controlled atmospheres and material handling.
This story uses material from Harper, with editorial changes made by Materials Today.
Marta Rusnak, PhD, Eng, Arch. Andrzej Butarewicz, PhD, Eng. and Sławomir Czarnecki, PhD, Eng. have been elected members of the Executive Committee of Academia Iuvenum to supervise the work of an elite group of young scientists for a year to come.
Researchers at the University of California (UC) Santa Barbara and eight other institutions have identified a key mechanism responsible for the lower efficiencies of organic solar cells and have demonstrated a way this hurdle might be overcome. Their results, reported in a paper in Nature, suggest the possibility of developing organic solar cells with efficiencies comparable to silicon-based cells.
The researchers identified a pathway in organic solar cells where current is lost, making them less efficient than silicon-based cells at converting sunlight into electricity. They then discovered a way to supress this pathway by manipulating molecules inside the solar cell to prevent an undesirable state leading to lost current. “It is an extensive work that took a long time to collect data,” said Thuc-Quyen Nguyen, a professor at UC Santa Barbara and one of the paper’s corresponding authors. Reviews and revisions alone took a year and half, she added.
Organic solar cells are flexible, lightweight, semi-transparent and cheap – features that mean the cells could greatly expand the range of applications for solar technology. For example, organic solar cells could be wrapped around the exteriors of buildings or coat glass windows and greenhouses to generate energy for indoor lighting, neither of which are possible with conventional silicon panels.
They are also far more environmentally friendly to produce. For instance, they are 1000 times thinner than silicon solar cells and can be produced at low temperatures via solution processing methods like printing, roll-to-roll coating, spraying and so forth.
“Organic solar cells can do lots of things that inorganic solar cells can’t, but their commercial development has plateaued in recent years, in part due to their inferior efficiency,” said first author Alexander Gillett from the University of Cambridge's Cavendish Laboratory in the UK. “A typical silicon-based solar cell can reach efficiencies as high as 20% to 25%, while organic solar cells can reach efficiencies of around 19% under laboratory conditions, and real-world efficiencies of about 10% to 12%.”
Organic solar cells generate electricity by loosely mimicking the natural process of photosynthesis in plants, except they ultimately use the energy of the Sun to create electricity rather than to convert carbon dioxide and water into glucose. When a photon hits a solar cell, it excites an electron and leaves behind a ‘hole’ in the material’s electronic structure. The combination of this excited electron and hole is known as an exciton. If the mutual attraction between the negatively charged electron and positively charged hole can be overcome, it is possible to harvest these electrons and holes as electrical current.
However, electrons in solar cells can lose their energy and fall back into the empty ‘hole’ in a process called charge recombination. Organic solar cells are more prone to recombination since there is a stronger attraction between the electron and hole in carbon-based materials than in silicon. This, in turn, affects their efficiency. Researchers usually employ two components to prevent electrons from recombining with holes: a donor material, which contributes electrons, and an acceptor material, which takes up electrons to generate and transport charges.
Using a combination of spectroscopy and computer modeling, the researchers were able to track the mechanisms at work in organic solar cells, from the absorption of photons to recombination. They found that a key loss mechanism in organic solar cells is caused by recombination of a particular type of exciton, known as a triplet exciton.
In organic solar cells, triplet excitons present a difficult problem to overcome, as they are energetically favourable. The researchers found that by engineering strong molecular interactions between the electron donor and electron acceptor materials, it is possible to keep the electron and hole further apart, preventing triplet excitons from forming.
This project began with a collaboration between the UC Santa Barbara and Cambridge teams. “I was so surprised when Alex shared the result on an analysis of a blend system developed at UCSB that showed it was possible to eliminate the triplet exciton loss,” Nguyen said.
Nguyen encouraged Gillett to analyze several other blends to make sure the result was universal. It took more than two years for him to collect the data with six research teams working together. “This work highlights the importance of collaborative research to advance science,” she added.
“The fact that we can use the interactions between components in a solar cell to turn off the triplet exciton loss pathway was really surprising,” said Gillett. “Our method shows how you can manipulate molecules to stop recombination from happening.”
The researchers say their method provides a clear strategy to creating organic solar cells with efficiencies of 20% or more by stopping recombination into triplet exciton states. As part of their study, the authors were also able to provide design rules for the electron donor and electron acceptor materials to achieve this aim.
The next hurdle for the field is to improve the lifetime of organic solar cells. The team is currently working to solve this problem via materials engineering.
“Now, synthetic chemists can design the next generation of donor and acceptor materials with strong molecular interactions to suppress this loss pathway,” Nguyen said. “This work shows the path forward to develop organic solar cells with efficiencies closer to silicon-based cells.”
This topological metal becomes superconducting at low temperature, which is a very rare occurrence of superconductivity in a kagome material.Ilija Zeljkovic, Boston College
Researchers have discovered a complex landscape of electronic states that can co-exist on a kagome lattice, resembling those in high-temperature superconductors. Led by a team of physicists from Boston College, the researchers report their findings in a paper in Nature.
The focus of the study was a bulk single crystal of a topological kagome metal known as CsV3Sb5 – a metal that becomes superconducting below 2.5K (-455°F). This exotic material is built from atomic planes composed of vanadium atoms arranged on a so-called kagome lattice – described as a pattern of interlaced triangles and hexagons – stacked on top of one another, with cesium and antimony spacer layers between the kagome planes.
This material offers a window into how the physical properties of quantum solids – such as light transmission, electrical conduction and response to a magnetic field – relate to the underlying geometry of the atomic lattice structure. Because their geometry causes destructive interference and 'frustrates' the kinetic motion of traversing electrons, kagome lattice materials are prized for offering unique and fertile ground for the study of quantum electronic states described as frustrated, correlated and topological.
The majority of experimental efforts thus far have focused on kagome magnets. The material the team examined is not magnetic, which opens the door to investigating how electrons in kagome systems behave in the absence of magnetism. The electronic structure of this material can be classified as 'topological', while high electrical conductivity makes it a 'metal'.
“This topological metal becomes superconducting at low temperature, which is a very rare occurrence of superconductivity in a kagome material,” said Ilija Zeljkovic, an associate professor of physics at Boston College and a lead co-author of the paper.
In a metal, electrons in the crystal form a liquid state; electrical conduction happens when the charged liquid flows under a voltage. The researchers used scanning tunneling spectroscopy to probe the quantum interference effects of the electron liquid in the kagome material, said Zeljkovic, who conducted the research with colleagues from Boston College and the University of California, Santa Barbara.
These experiments revealed a 'cascade' of symmetry-broken phases of the electron liquid, driven by the correlation between the electrons in the material. Occurring consecutively as the temperature of the kagome material is lowered, standing waves known as charge density waves emerge first in the electron liquid, with a periodicity different from the underlying atomic lattice. At lower temperatures, a new standing wave component nucleates along just one direction of the crystal axes, such that electrical conduction along this direction is different than in any other direction.
These phases develop in the normal state – or the non-superconducting metallic state – and persist below the superconducting transition, said Ziqiang Wang, professor of physics at Boston College and co-author of the paper. The experiments demonstrate that superconductivity in CsV3Sb5 emerges from, and coexists with, a correlated quantum electronic state that breaks spatial symmetries of the crystal.
These findings could have strong implications for how the electrons form so-called Cooper pairs and turn into a charged superfluid at an even lower temperature, or a superconductor capable of electrical conduction without resistance. In this family of kagome superconductors, other research has already suggested the possibility of unconventional electron pairing, said Zeljkovic.
Researchers in the field have also noted a phenomenon called time-reversal symmetry breaking in CsV3Sb5. This symmetry rule – which holds that actions would be performed in reverse if time were to run backwards – is typically broken in magnetic materials, but the kagome metal shows no substantial magnetic moments. According to Zeljkovic, next steps in this research are to understand this apparent contradiction and how the electronic states revealed in this recent work are related to time-reversal symmetry breaking.
The amount of research being conducted into these recently discovered kagome lattice superconductors is reflected in an associated paper in Nature. Also co-authored by Wang, the paper reports the observation of novel standing waves formed by Cooper pairs with yet another periodicity in the same kagome superconductor, CsV3Sb5.
“The publishing of these two reports side-by-side not only reveals new and broad insights into kagome lattice superconductors, but also signals the high level of interest and excitement surrounding these materials and their unique properties and phenomena, which researchers at Boston College and institutions around the world are discovering with increasing frequency,” Wang said.
This story is adapted from material from Boston College, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
Lanxess has developed a new composite made from natural flax fibers and bio-based polylactic acid as part of its Tepex range of continuous-fiber-reinforced thermoplastic material.
According to the company, flax fibers have a lower density than glass fibers, and so composites made with these fibers are lighter in weight than their glass fiber reinforced counterparts. When coupled with transparent matrix plastics such as polylactic acid, the reinforcing flax fabric yields surfaces with a brown natural carbon fiber look.
‘We have combined fabrics made from s a matrix material and thereby developed a composite manufactured entirely from natural resources,’ said Dr Stefan Seidel, head of research and development. ‘We are now able to produce it to a level of quality suitable for large-scale production.’
Lanxess says that the biocomposites can be completely recycled as purely thermoplastic systems as part of closed-loop material cycles. ‘Offcuts and production waste can be regranulated and easily injection-molded or extruded, either alone or mixed with unreinforced or short fiber reinforced compound new materials,’ said Seidel.
This story uses material from Lanxess, with editorial changes made by Materials Today.
Technology company Schunk has opened two new innovation center in the towns of Reiskirchen and Heuchelheim, Germany covering ceramics and carbon fibers.
The €30 million centers will focus on the company’s core competencies of graphite, carbon and carbon fibers as well as new materials, according to Dr Ulrich von Hülsen, board member. ‘The world is facing enormous challenges in the areas of climate protection, mobility and energy supply. All these megatrends require new materials to solve the existing problems.’
Schunk reports that the building contains two special climate control units making it possible to create three different climates, and a 3D printing technical center for manufacturing continuous fibers and multi-material ceramics.
This story uses material from Schunk, with editorial changes made by Materials Today.
The MPIF has released details of a new self-study course covering powder metallurgy and particulate materials processing.
The course, run by Dr Randall M German, contains 30 pre-recorded segments averaging 60 minutes each. These videos will be open to the student for six months from the date of purchase, the organization said.
After completing the course, Dr German says that students should be able to differentiate manufacturing methods for the production of metal powders, discuss particle morphology, understand the requirements of lubricants and binders, describe common consolidation/shaping processes, discuss sintering furnaces and atmospheres, interpret a phase diagram and resulting microstructures, describe post-sintering operations, and interpret materials properties and recognize management issues including safety, health, cost, efficiency, markets, and applications.
Student will have the opportunity to sit for a Level 1 Powder Metallurgy Technologist Certification examination for free within 18 months of starting the course. This certification is formal acknowledgement by APMI International that an individual has demonstrated comprehension of a specified body of knowledge encompassing the broad field of powder metallurgy and particulate materials.
The course costs US$1,400 per individual for less than six employees, US$1,300 per individual for six-nine employees, and US$1,000 per individual for 10 or more employees.
This story uses material from the MPIF, with editorial changes made by Materials Today.
The collection, appearing in the Journal Cement and Concrete Composites, aims to highlight research addressing problems of low productivity and shortages of skilled labor in the construction sector – through developing digital construction processes for the production of concrete components.
According to Guest Editor Viktor Mechtcherine, the development of digital construction processes for the production of concrete components in a prefabrication plant or directly on the construction site is a decisive step towards introducing the “Industry 4.0” concept into the construction industry. And he added, "the technological, economic, ecologic and social potentials of digital concrete construction have now been recognized by many scientists and industrial stakeholders; the extent of research and innovation in this field is increasing month by month”.
Leading research teams from all over the world were invited to submit to the Special Issue, and delivered papers on the progress of new technologies. Of special value is a series of review papers from internationally renowned experts offering comprehensive overviews and critical analyses of the state-of-the-art in various fields of interest directly related to 3D concrete printing. These review papers cover elements such as:
mix design concepts for 3D concrete printing and use of sustainable materials in this context;
analytical and numerical simulation in the process assessment;
integration of reinforcement in 3D concrete printing, and large-scale concrete printing.
In addition, several articles in the Special Issue present new technological approaches to 3D concrete printing, new material compositions for digital concrete, and novel methods for assessing the quality of printable cement-based materials and printed material and elements. There are also papers devoted to the different strategies of steering serial processes involved in 3D concrete printing: material delivery to printhead, printhead process, material flow during its deposition and behavior of print material / element after deposition.
If you’re interested in reading this collection on, you can view it here.
The Editorial Team of Materials Today Physics journal and Elsevier are proud to honour Highly-cited and Hot papers published recently and encourage authors to contribute their excellent work to the journal.
TiB2 thin film enabled efficient NH3 electrosynthesis at ambient conditions - Materials Today Physics
According to the MPIF, the award was established in 2018 to recognize authors of manuscripts for excellence in scientific and technical written communications.
Paper excellence is measured using a system of four quality standards: (1) the paper is scientifically or technically new, innovative, or is a constructive review; (2) has clear presentation in writing, organization, graphics, format, and has professional integrity; (3) has clear industrial application; and (4) has long-term value.
A new report published by the Society of Motor Manufacturers and Traders (SMMT) says that vehicles as the UK’s single most valuable goods trade export.
According to the organization, vehicle export revenues reached £27 billion in 2020, making them more valuable to the UK than power-generating machinery and gold, despite the Covid-19 pandemic.
The UK automotive sector generated a total trade revenue of £74 billion. More than 80% of British-built cars and more than 60% of light commercial vehicles are destined for export, the SMMT said.
‘As the world re-emerges from the pandemic, the diversity and importance of Britain’s automotive industry is the UK’s competitive advantage for restarting growth, creating jobs and tackling climate change,’ said Mike Hawes, SMMT chief executive.
This story uses material from the SMMT, with editorial changes made by Materials Today.
The MPIF says that a National Science Foundation (NSF) grant will be provided to some students from US colleges and universities to attend its PowderMet2022 and AMPM2022 conferences, taking place in Portland, Oregon, in June 2022.
The grants will cover the full registration fee and hotel accommodation in double occupancy, the organization said.
The two conferences will include more than 200 presentations on the latest research and developments in PM, particulate materials, and metal additive manufacturing, and provide an opportunity for college students to network with industry leaders, present their own research, and learn from those already working in the industry.
Applicants are required to be from US institutions, attend the entire conference, submit a poster on engineering activities at their institution, and provide a 25-minute presentation.
Thermoset composite company Norplex has opened a new manufacturing center for prepreg manufacture in Manhattan, Montana.
According to the company, the facility will initially make fabric and unidirectional glass epoxy prepregs, its EnableX prepreg molding system and NorPLY line of fatigue resistant laminates for the transportation, sporting goods and recreation, renewable energy, medical, industrial, and aerospace markets.
The 32,000 ft2 plant houses a custom-built direct impregnation hot melt prepreg line that can reportedly run various fabrics and unidirectional rovings with diverse chemistries.
‘We’re excited to be stepping into the Advanced Composites sector as part of our long-term commitment to market development and business growth for all of our stakeholders,’ said Tom Merrell, president of Norplex.
This story uses material from Norplex, with editorial changes made by Materials Today.
Austria-based Action Composites has announced its acquisition of thyssenkrupp Carbon Components (tkCC) GmbH.
Financial details of the transaction have not been disclosed.
thyssenkrupp Carbon Components was founded in 2012 and makes composite rims for sports cars, motorbikes and chassis components, while Action Composites, founded in 2011, makes automotive composites sector and has annual sales of around €70 million with around 1,800 employees at four locations.
‘For Action Composites, the purchase of tkCC is a further step towards quickly achieving global market leadership in the field of CFRP [carbon fiber reinforced polymer] wheels (motorcycle and passenger car),’ said Christine Beuleke, managing director of Action Composites. ‘The location in Saxony, with its proximity to the Technical University of Dresden, forms an excellent basis for the Action Composites Group's new technology and testing center. A special focus here is on the development of sustainable materials and production processes.’
This story uses material from Action Composites, with editorial changes made by Materials Today.
Airbus says that its second European Service Module (ESM) for NASA’s Orion spacecraft has been manufactured.
The European Space Agency (ESA) has selected Airbus as the prime contractor for the development and manufacture of six ESMs altogether.
Plans are for the Orion spacecraft to transport astronauts beyond low Earth orbit for the first time since the end of the Apollo programme in the 1970s. The ESMs will provide propulsion, power and thermal control and will supply astronauts with water and oxygen on future missions.
According to Airbus, each ESM is a cylinder around 4m2 and comprises more than 20,000 parts and components including carbon fiber sheets and panels. It has a four-wing solar array (19m across when unfurled) that generates enough energy to power two households.
‘Delivery of the second European Service Module for NASA’s Orion spacecraft marks another huge step forward on the journey to return astronauts to the Moon. Working hand in hand with our customers ESA and NASA, and our industrial partner, Lockheed Martin Space, the programme is moving apace and we are ready to meet the challenges of returning to the lunar surface in 2024,’ said Andreas Hammer, Head of Space Exploration at Airbus.
This story uses material from Airbus, with editorial changes made by Materials Today.
Scientists at Lawrence Livermore National Laboratory (LLNL) have researched alternative shapes to the Gaussian beams commonly used in high-power laser printing 3D printing processes such as laser powder bed fusion (LPBF).
According to the institution, laser beams traditionally used in metal additive manufacturing (AM) can have drawbacks that can lead to defects and poor mechanical performance.
In tests, the researchers found that using Bessel beams, that have self-healing and non-diffraction properties, reduced the likelihood of pore formation and ‘keyholing’, a porosity-inducing phenomenon in LPBF exacerbated by the use of Gaussian beams.
LLNL researchers said the work indicates that alternative shapes such as Bessel beams could reduce the large thermal gradient and complex melt pool instabilities occurring where the laser meets the metal powder during LBPF. The issues are predominantly caused by Gaussian beam shapes that most off-the-shelf, high-power laser systems typically output, they said.
‘With a Bessel beam, the fact that we redistribute some of that energy away from the center means we can engineer thermal profiles and reduce thermal gradients to aid microstructural grain refinement and, ultimately, result in denser parts and smoother surfaces,’ said lead author and LLNL research scientist Dr Thej Tumkur Umanath.
Conventional beams are also prone to diffraction (spreading) as they propagate, while Bessel beams afford a greater depth of focus due to their non-diffractive properties. The researchers noted an increased tolerance to the placement of the workpiece with respect to the laser’s focal point using Bessel beams, according to Dr Umanath.
‘Bessel beams have been used extensively in imaging, microscopy and other optical applications for their non-diffractive and self-healing properties, but beam-shape engineering approaches are rather uncommon in laser-based manufacturing applications,’ Tumkur explained. ‘Our work addresses the seeming disconnect between optical physics and materials engineering in the metal additive manufacturing community by incorporating designer beam shapes to achieve control over melt pool dynamics.’
The LLNL team shaped the beams by running the laser through two conical lenses to produce a donut shape, before passing it through additional optics and a scanner to create ‘rings’ around the central beam. Installed in a commercial printing machine in LLNL’s Advanced Manufacturing Laboratory, the researchers used the experimental setup to print cubes and other shapes from stainless steel powder.
Through high-speed imaging, researchers studied the dynamics of the melt pool, observing a substantial reduction in melt pool turbulence and mitigation of spatter, which can lead to pore formation.
In mechanical studies and simulations, the team found that parts built with Bessel beams were denser, stronger and had more robust tensile properties than structures built with conventional Gaussian beams.
LLNL computer scientist Saad Khairallah used the LLNL-developed multiphysics code ALE3D to simulate the interaction of both Gaussian and Bessel beam laser shapes with single tracks of metal powder material. By comparing the resulting tracks, the team found the Bessel beam demonstrated improved thermal gradients over Gaussian beams, encouraging better microstructure formation. They also achieved better energy distribution with Bessel beams, avoiding the ‘hot spot’ generation found in Gaussian beams, which produce deep melt pools and form pores.
This story uses material from LLNL, with editorial changes made by Materials Today.
A team led by scientists at the US Department of Energy (DOEs)’s Oak Ridge National Laboratory (ORNL) has found a rare quantum material in which electrons move in coordinated ways, essentially 'dancing'. Straining this material creates an electronic band structure that sets the stage for exotic, more tightly correlated behavior – akin to tangoing – among Dirac electrons, especially mobile electric charge carriers that may someday lead to faster transistors. The team reports its results in a paper in Science Advances.
“We combined correlation and topology in one system,” said co-principal investigator Jong Mok Ok, who conceived the study with principal investigator Ho Nyung Lee of ORNL. Topology probes properties that are preserved even when a geometric object undergoes deformation, such as when it is stretched or squeezed. “The research could prove indispensable for future information and computing technologies,” added Ok, a former ORNL postdoctoral fellow.
In conventional materials, electrons move predictably (for example, lethargically in insulators or energetically in metals). But in quantum materials where electrons strongly interact with each other, physical forces cause the electrons to behave in unexpected but correlated ways – one electron’s movement forces nearby electrons to respond.
To study this tight tango in topological quantum materials, Ok led the synthesis of an extremely stable crystalline thin film of a transition metal oxide. He and his colleagues fabricated the film using pulsed-laser epitaxy, and then strained it to compress the layers and stabilize a phase that does not exist in the bulk crystal. The scientists were the first to stabilize this phase.
Using theory-based simulations, co-principal investigator Narayan Mohanta, a former ORNL postdoctoral fellow, predicted the band structure of the strained material. “In the strained environment, the compound that we investigated, strontium niobate, a perovskite oxide, changes its structure, creating a special symmetry with a new electron band structure,” Mohanta said.
Different states of a quantum mechanical system are called 'degenerate' if they have the same energy value upon measurement. Electrons are equally likely to fill each degenerate state. In this case, the special symmetry results in four states occurring at a single energy level.
“Because of the special symmetry, the degeneracy is protected,” Mohanta said. “The Dirac electron dispersion that we found here is new in a material.” He performed calculations with Satoshi Okamoto, who developed a model for discovering how crystal symmetry influences band structure.
“Think of a quantum material under a magnetic field as a 10-story building with residents on each floor,” explained Ok. “Each floor is a defined, quantized energy level. Increasing the field strength is akin to pulling a fire alarm that drives all the residents down to the ground floor to meet at a safe place. In reality, it drives all the Dirac electrons to a ground energy level called the extreme quantum limit.”
“Confined here, the electrons crowd together,” added Lee. “Their interactions increase dramatically, and their behavior becomes interconnected and complicated.” This correlated electron behavior, a departure from a single-particle picture, sets the stage for unexpected behavior, such as electron entanglement. In entanglement, a state Einstein called “spooky action at a distance”, multiple objects behave as one. It is key to realizing quantum computing.
“Our goal is to understand what will happen when electrons enter the extreme quantum limit, where we find phenomena we still don’t understand,” Lee said. “This is a mysterious area.”
Speedy Dirac electrons hold promise in materials such as graphene, topological insulators and certain unconventional superconductors. ORNL’s unique material is a Dirac semimetal, in which electron valence and conduction bands cross, with this topology yielding surprising behavior. Ok led measurements of the Dirac semimetal’s strong electron correlations.
“We found the highest electron mobility in oxide-based systems,” Ok said. “This is the first oxide-based Dirac material reaching the extreme quantum limit.”
That bodes well for advanced electronics. Theory predicts that it should take about 100,000 tesla (a unit of magnetic measurement) for electrons in conventional semiconductors to reach the extreme quantum limit. The researchers took their strain-engineered topological quantum material to Eun Sang Choi of the National High Magnetic Field Laboratory at the University of Florida to see what it would take to drive electrons in this material to the extreme quantum limit. There, Choi measured quantum oscillations showing the material would require only 3 tesla to reach the limit.
Other specialized facilities allowed the scientists to experimentally confirm the behavior Mohanta predicted. These experiments were conducted at low temperatures so that the electrons could move around without getting bumped by atomic-lattice vibrations.
Jeremy Levy’s group at the University of Pittsburgh and the Pittsburgh Quantum Institute confirmed the quantum transport properties. Using synchrotron X-ray diffraction, Hua Zhou at the Advanced Photon Source, a DOE Office of Science user facility at Argonne National Laboratory, confirmed that the material’s crystallographic structure, stabilized in the thin film phase, yielded the unique Dirac band structure. Sangmoon Yoon and Andrew Lupini, both of ORNL, conducted scanning transmission electron microscopy experiments at ORNL showing that the epitaxially grown thin films had sharp interfaces between layers and that the transport behaviors were intrinsic to strained strontium niobate.
“Until now, we could not fully explore the physics of the extreme quantum limit due to the difficulties in pushing all electrons to one energy level to see what would happen,” Lee said. “Now, we can push all the electrons to this extreme quantum limit by applying only a few tesla of magnetic field in a lab, accelerating our understanding of quantum entanglement.”
Moving heat around where you want it to go—adding it to houses and hairdryers, removing it from car engines and refrigerators—is one of the great challenges of engineering. All activity generates heat, because energy escapes from everything we do. But too much heat can wear out batteries and electronic components – like the parts in an aging laptop that runs too hot to actually sit on your lap. If you can’t get rid of heat, you’ve got a problem.
Scientists at the University of Chicago have now invented a new way to funnel heat around at the microscopic level: a thermal insulator made using an innovative technique. The scientists stack ultra-thin layers of crystalline sheets on top of each other, but rotate each layer slightly, creating a material with atoms that are aligned in one direction but not in the other.
“Think of a partly-finished Rubik’s cube, with layers all rotated in random directions,” said Shi En Kim, a graduate student with the Pritzker School of Molecular Engineering, who is first author of a paper on this work in Nature. “What that means is that within each layer of the crystal, we still have an ordered lattice of atoms, but if you move to the neighboring layer, you have no idea where the next atoms will be relative to the previous layer—the atoms are completely messy along this direction.”
The result is a material that is extremely good at both containing heat and moving it, albeit in different directions—an unusual ability at the microscale, and one that could have very useful applications in electronics and other technologies.
“The combination of excellent heat conductivity in one direction and excellent insulation in the other direction does not exist at all in nature,” said Jiwoong Park, professor of chemistry and molecular engineering at the University of Chicago, and lead author of the paper. “We hope this could open up an entirely new direction for making novel materials.”
Scientists are constantly on the search for materials with unusual properties, because they can unlock completely new capabilities for devices such as electronics, sensors, medical technology or solar cells. For example, MRI machines were made possible by the discovery of a strange material that can conduct electricity perfectly.
Park’s group had been investigating ways to make extremely thin layers of materials, which are just a few atoms thick. Normally, the materials used for devices are made up of extremely regular, repeating lattices of atoms, which makes it very easy for electricity (and heat) to move through the material. But the scientists wondered what would happen if they instead rotated each successive layer slightly as they stacked them.
They measured the results and found that a microscopic wall made of this material was extremely good at preventing heat from moving between layers. “The thermal conductivity is just amazingly low – as low as air, which is still one of the best insulators we know,” said Park. “That in itself is surprising, because it’s very unusual to find that property in a material that is a dense solid – those tend to be good heat conductors.”
But the point that was really exciting for the scientists was when they measured the material’s ability to transport heat along single layers in the wall, and found it could do so very easily.
Those two properties in combination could be very useful. For example, making computer chips smaller and smaller results in more and more power running through a small space, creating an environment with a high 'power density' – a dangerous hotspot, said Kim.
“You’re basically baking your electronic devices at power levels as if you are putting them in a microwave oven,” she said. “One of the biggest challenges in electronics is to take care of heat at that scale, because some components of electronics are very unstable at high temperatures.
“But if we can use a material that can both conduct heat and insulate heat at the same time in different directions, we can siphon heat away from the heat source – such as the battery – while avoiding the more fragile parts of the device.”
That capability could open doors to experiments with materials that have been too heat-sensitive for engineers to use in electronics. In addition, creating an extreme thermal gradient – where something is very hot on one side and cool on the other – is difficult to do, particularly at such small scales, but could have many applications in technology.
“If you think of what the windowpane did for us – being able to keep the outside and inside temperatures separate – you can get a sense of how useful this could be,” Park said.
The scientists only tested their layering technique in one material, called molybdenum disulfide, but think this mechanism should be general across many others. “I hope this opens up a whole new direction for making exotic thermal conductors,” Kim said.
This story is adapted from material from the University of Chicago, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
In the past few decades, metal 3D printing has spearheaded efforts to create custom parts with intricate shapes and high functionality. But as additive manufacturers have utilized more metal alloys for their 3D printing needs, so they have faced challenges in creating uniform, defect-free parts.
Now, in a new study, researchers at Texas A&M University have created superior metal parts by refining a 3D-printing method called laser powder bed fusion. Using a combination of machine learning and single-track 3D printing experiments, they were able to identify the favorable alloy chemistries and process parameters, like laser speed and power, required to print parts with uniform properties at the microscale.
“Our original challenge was making sure there are no pores in the printed parts because that's the obvious killer for creating objects with enhanced mechanical properties,” said Raiyan Seede, doctoral student in the Department of Materials Science and Engineering. “But having addressed that challenge in our previous work, in this study, we take deep dives into fine-tuning the microstructure of alloys so that there is more control over the properties of the final printed object at a much finer scale than before.” The researchers report their findings in a paper in Additive Manufacturing.
Like other 3D-printing methods, laser powder bed fusion builds 3D metal parts layer-by-layer. The process starts with rolling a thin layer of metal powder on a base plate and then melting the powder by scanning a laser beam along tracks that trace the cross-sectional design of the intended part. Then another layer of the powder is applied and the process is repeated, gradually building up the final part.
Alloy metal powders used for additive manufacturing can be quite diverse, containing a mixture of metals, such as nickel, aluminum and magnesium, at different concentrations. During printing, these powders cool rapidly after being heated by the laser beam. Since the individual metals in the alloy powder have very different cooling properties and solidify at different rates, this can create a type of microscopic flaw called microsegregation.
“When the alloy powder cools, the individual metals can precipitate out,” explained Seede. “Imagine pouring salt in water. It dissolves right away when the amount of salt is small, but as you pour more salt, the excess salt particles that do not dissolve start precipitating out as crystals. In essence, that’s what is happening in our metal alloys when they cool quickly after printing.” This can produce tiny pockets with slightly different concentrations of the metal ingredients than other regions of the printed part, compromising its mechanical properties.
To try to prevent this happening, the research team investigated the solidification of four alloys containing nickel and one other metal ingredient. In particular, for each of these alloys, they studied the physical states or phases present at different temperatures for increasing concentrations of the other metal in the nickel-based alloy. This produced detailed phase diagrams, from which the researchers could determine the chemical composition of the alloy that would lead to minimum microsegregation during additive manufacturing.
Next, they melted a single track of the alloy metal powder at different laser settings and determined the process parameters that would yield porosity-free parts. They then combined the information gathered from the phase diagrams with the results from the single-track experiments to get a consolidated view of the laser settings and nickel alloy compositions that would yield a porosity-free printed part without microsegregation.
Lastly, they went a step further and trained machine-learning models to identify patterns in their single-track experiment data and phase diagrams, in order to develop an equation for microsegregation applicable to any other alloy. According to Seede, this equation is designed to predict the extent of segregation given the solidification range, material properties, and laser power and speed.
“Our methodology eases the successful use of alloys of different compositions for additive manufacturing without the concern of introducing defects, even at the microscale,” said Ibrahim Karaman, professor and head of the Department of Materials Science and Engineering. “This work will be of great benefit to the aerospace, automotive and defense industries that are constantly looking for better ways to build custom metal parts.”
Research collaborators Raymundo Arroyavé and Alaa Elwany added that the uniqueness of their methodology is its simplicity, which means the methodology can easily be adapted by industries to build sturdy, defect-free parts with an alloy of choice. They noted that their approach contrasts with prior efforts that have primarily relied on expensive, time-consuming experiments for optimizing processing conditions.
This story is adapted from material from Texas A&M 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.
Our tests indicate that these liquid-metal copper-coated fabrics demonstrate superior antimicrobial performance compared to other copper-coated surfaces and two commercial antimicrobial facemasks that rely on copper and silver respectively.Vi Khanh Truong, RMIT University
An international team of researchers used liquid gallium to create an antiviral and antimicrobial coating and tested it on a range of fabrics, including facemasks. The coating adhered more strongly to fabric than some conventional metal coatings, and eradicated 99% of several common pathogens within five minutes.
“Microbes can survive on the fabrics hospitals use for bedding, clothing and face masks for a long time,” says Michael Dickey, professor of chemical and biomolecular engineering at North Carolina State University (NC State) and co-corresponding author of a paper on this work in Advanced Materials. “Metallic surface coatings such as copper or silver are an effective way to eradicate these pathogens, but many metal particle coating technologies have issues such as non-uniformity, processing complexity or poor adhesion.”
Together with colleagues from NC State, Sungkyunkwan University (SKKU) in Korea and RMIT University in Australia, Dickey set out to develop a simple, cost-effective way to deposit metal coatings on fabric. First, the researchers placed liquid gallium (Ga) into an ethanol solution and used sound waves – a process known as sonication – to form Ga nanoparticles. They spray-coated this nanoparticle solution onto the fabric, where the Ga adhered to the fibers as the ethanol evaporated.
They then dipped the Ga-coated fabric into a copper sulfate solution, creating a spontaneous galvanic replacement reaction. This reaction deposits copper onto the fabric, creating a coating of liquid metal copper alloy nanoparticles.
To test the coated fabric’s antimicrobial properties, the research team exposed it to three common microbes: Staphylococcus aureus, Escherichia coli and Candida albicans. These microbes grow aggressively on non-coated fabrics, but the copper-alloy-coated fabric eradicated over 99% of the pathogens within five minutes, making it significantly more effective than control samples coated with only copper.
The team collaborated with Elisa Crisci, assistant professor of virology at NC State, and Frank Scholle, associate professor of biological sciences at NC State, to show that the coatings also work against viruses. They tested the coatings against human influenza (H1N1) and coronavirus (HCoV 229E, which is in the same family as SARS-CoV-2). The coatings eradicated the viruses after five minutes.
“Our tests indicate that these liquid-metal copper-coated fabrics demonstrate superior antimicrobial performance compared to other copper-coated surfaces and two commercial antimicrobial facemasks that rely on copper and silver respectively,” says Vi Khanh Truong from RMIT University and co-corresponding author of the paper.
“This is a better method for generating metal coatings of fabrics, particularly for antimicrobial applications, both in terms of adhesion and antimicrobial performance,” says Ki Yoon Kwon, postdoctoral associate at SKKU and first author of the paper.
“It could also work with metals other than copper, such as silver,” adds Tae-il Kim, a professor at SKKU and co-corresponding author of the paper. “It is also a simple method, which should be relatively straightforward to scale up for mass production.”
Wrocław Tech has participated in the Erasmus Mundus Joint Master Degree programme for several years. Together with universities in Marseille and Rome, we train students to become specialists in Chemical NanoEngineering (CNE).
The Society of Motor Manufacturers and Traders (SMMT) says that 32,721 battery electric vehicles (BEVs) were registered in September – reportedly the best monthly performance ever.
However, new car registrations in general fell 34.4% compared to 2020 to 215,312 units, due to an ongoing shortage of semiconductors, the SMMT said.
BEVs now hold a market share of 15.2% in the UK, while the share of plug-in hybrid electric vehicles (PHEV) grew to 6.4%, meaning more than one in five new cars registered in September was zero-emission capable. Meanwhile, hybrid electric vehicles (HEVs) grew their overall market share from 8.0% in 2020 to 11.6%, with 24,961 registered in the month, according to the organziation’s report.
‘The rocketing uptake of plug-in vehicles, especially battery electric cars, demonstrates the increasing demand for these new technologies,’ said Mike Hawes, SMMT chief executive. ‘However, to meet our collective decarbonisation ambitions, we need to ensure all drivers can make the switch – not just those with private driveways – requiring a massive investment in public recharging infrastructure.'
This story uses material from the SMMT, with editorial changes made by Materials Today.
Could Carbon be a promising candidate for post-lithium batteries? The Journal Synthetic Metals has published a new review paper on the theme.
According to the abstract, the paper – “Carbon in lithium-ion and post-lithium-ion batteries: Recent features”, seeks to review and analyze the developments made during last few decades on the place of carbon in batteries. “First identified as an anode of interest in the form of graphite, carbon has also made a place for itself as conductive agent added during electrode formulation or also as buffer with electrochemical active oxide processing by conversion”, the authors report. “The focus is primarily on how to decrease the irreversibility of classical anode materials then how to increase its whole performance through nanostructures, mainly CNTs and graphene”.
According to Synthetic Metals Editor Dr. Emmanuel Flahaut, "Carbon-based materials occupy a very central place in the field of energy storage. Focusing on lithium-ion batteries, this review highlights the dual role that carbon will also play in the era of post-lithium battery materials, both as anode and as support for reversible cathode material. Recent works including operando measurements highlight the specific potential of carbon nanomaterials such as carbon nanotubes and graphene for the future high-rate anodes in all kinds of batteries."
3D printing specialist EOS is running a free short webinar covering ways to access UK government support for additive manufacturing (AM) projects.
‘Transforming the industry with additive manufacturing’ takes place on 12 October at 11am.
According to the company, manufacturers can see the benefits of AM and understand the need to evolve their supply chains, but many struggle to get over the ‘perceived hurdle’ of the level of investment required for production grade equipment.
The webinar will cover UK Government tax incentives and funding support, including the Treasury’s super deduction scheme and R&D tax credits.
Charles Ross & Son Co says that its ribbon blenders for multi-phase mixing now come with an optional pressure feed vessel.
While minor liquid ingredients must be thoroughly blended into powder or other solids, a pressure feed vessel enables 100% discharge of the liquid component through a spray bar and into the blending zone, ensuring even mixing and consistent batches, the company said.
Instead of manually pouring liquids through an open blender cover or safety grating, utilizing a pressure feed vessel and spray bar also facilitates liquid addition while the blender is closed, minimizing dusting and safety issues. The spray bar typically includes four or more spray nozzles so that liquids are uniformly distributed along the entire length of the blender. The pressure feed vessel eliminates the need for a pump to deliver liquids to the spray bar, according to Ross.
The pressure feed vessel, which is designed for compressed air supply up to 20 psig or higher, has an absence of residual product in the piping, and after the blending cycle, it can assist with CIP/washdown, the company said.
The vessels are available in various sizes to accommodate the required volume of the additive liquid phase, and can be mounted and plumbed to ROSS Ribbon Blenders which range from 1/2 to 500 ft3 working capacity.
This story uses material from Charles Ross, with editorial changes made by Materials Today.
Sabic has opened a new polypropylene (PP) compounding line in Genk, Belgium.
According to the company, the new line is an addition to the company’s existing production capacity will use raw materials from Sabic’s PP plants at Gelsenkirchen, Germany, and Geleen, The Netherlands.
'This investment is part of our business strategy for growth through advanced PP compound solutions designed to help customers develop next-generation lightweight applications in industries such as automotive, home appliances and consumer goods,’ said Lada Kurelec, general manager at Sabic.
This story uses material from Sabic, with editorial changes made by Materials Today.
Due to their iridescent colors, opals have been considered particularly precious gemstones since antiquity. The way these stones shimmer is caused by their nanostructures.
A research group led by Markus Retsch at the University of Bayreuth in Germany has now produced colloidal crystals that mimic such nanostructures, for use as a new type of sensor that can visibly and continuously document the temperature in the environment over a defined period. Such sensors could be used for monitoring temperature-sensitive processes. The scientists report the novel colloidal crystal sensor in a paper in Advanced Materials.
Attractive applications are already in sight for this new type of sensor. "For the safe operation of modern high-performance batteries, it is important that they are exposed to only moderate temperatures for many hours of operation," says Marius Schöttle, a doctoral researcher at the University of Bayreuth and lead author of the paper.
"Short-term temperature spikes can endanger the safety and service life of the batteries. With the help of the new sensors, compliance with uniform ambient temperatures can be monitored reliably. Moreover, the sensor is already pre-programmed due to its material composition: it works autonomously and cannot be manipulated afterward."
"We have developed a sensor that is sensitive to time and temperature – without the need for complex electronics or special measuring devices," says Markus Retsch, a professor of physical chemistry and coordinator of the new study. "In addition, the artificial crystals we synthesized represent a new class of materials that are very interesting for fundamental research. It is possible that these colloidal gradients will help us to track down previously inaccessible physical phenomena."
Opals consist of spherical particles that form superordinate nanostructures. Interactions between these highly symmetrical nanostructures and visible light make the surfaces shimmer in the most diverse colors. The same is true for the wings of butterflies and some beetles. In recent years, natural and artificial representatives of this class of materials have been increasingly studied.
At the University of Bayreuth, Retsch and his research team investigated whether nanostructured materials can be produced using the same construction principle, but using mixtures of different particles with technologically attractive properties. Their vision was to realize nanostructured films that gradually change their physical properties along a certain direction.
The researchers found they could produce this unique gradual behavior by simply varying the composition of a binary particle mixture. For this purpose, they developed an experimental set-up that allowed the preparation of colloidal crystals made up of two distinct types of latex particle. These particles differed in the temperature at which they transition from a hard, glassy state to a soft, viscous state, known as the glass-transition temperature.
When these latex particles transition to the soft, viscous state they merge together, causing them to irretrievably lose their iridescent colors. Technically speaking, this irreversible dry sintering process creates a colorless film layer.
The researchers created colloidal crystals from both types of particles, utilizing a newly developed gradient fabrication technique to vary the proportion of the two particles steadily along the length of the crystals. The structure of the crystals is always the same: within each crystal, the proportion of particles with a higher glass-transition temperature, which are more stable, increases continuously towards one side. Comparative studies have shown that a larger percentage of more stable particles causes a slower structural degradation within the crystal and retards the resulting color loss.
The Bayreuth team has now used this discovery to fine-tune various colloidal crystals. A colloidal crystal in which the proportion of stable particles changes steadily can function as a temperature sensor: the higher the temperature over a defined period, the further the color loss spreads along the gradient direction. Since the color losses are irreversible, this means the sensor can document the ambient temperature as a function of time.
This story is adapted from material from the University of Bayreuth, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.
The 2D hybrid metal halide-based device used here is smaller and more economical to produce, is robust and works well at higher temperatures. This suggests that 2D hybrid metal halide materials may prove superior to the current conventional semiconductor materials for THz applications.Dali Sun, North Carolina State University
Researchers have utilized two-dimensional (2D) hybrid metal halides in a device that allows directional control of terahertz radiation generated by a spintronic scheme. The device has better signal efficiency than conventional terahertz generators, and is thinner, lighter and less expensive to produce.
Terahertz (THz) refers to the part of the electromagnetic spectrum between microwave and optical (i.e., frequencies between 100GHz and 10THz), and THz technologies have shown promise for applications ranging from faster computing and communications to sensitive detection equipment. However, creating reliable THz devices has proved challenging due to their size, cost and energy conversion inefficiency.
“Ideally, THz devices of the future should be lightweight, low-cost and robust, but that has been difficult to achieve with current materials,” says Dali Sun, assistant professor of physics at North Carolina State University and co-corresponding author of a paper on this work in Nature Communications. “In this work, we found that a 2D hybrid metal halide commonly used in solar cells and diodes, in conjunction with spintronics, may meet several of these requirements.”
The 2D hybrid metal halide in question is a popular and commercially available synthetic hybrid semiconductor: butyl ammonium lead iodine. Spintronics refers to controlling the spin of an electron, rather than just using its charge, in order to create energy.
Sun and colleagues from Argonne National Laboratories, the University of North Carolina at Chapel Hill and Oakland University created a device that layered the 2D hybrid metal halide with a ferromagnetic metal. They then excited this device with a laser, creating an ultrafast spin current that in turn generated THz radiation.
Not only did this 2D hybrid metal halide device outperform larger, heavier and more expensive THz emitters currently in use, but the researchers found that the 2D hybrid metal halide’s properties allowed them to control the direction of the THz transmission.
“Traditional terahertz transmitters were based upon ultrafast photocurrent,” Sun says. “But spintronic-generated emissions produce a wider bandwidth of THz frequency, and the direction of the THz emission can be controlled by modifying the speed of the laser pulse and the direction of the magnetic field, which in turn affects the interaction of magnons, photons and spins, and allows us directional control.”
Sun believes this work could be a first step in exploring 2D hybrid metal halide materials for potential use in a range of spintronic applications.
“The 2D hybrid metal halide-based device used here is smaller and more economical to produce, is robust and works well at higher temperatures,” Sun says. “This suggests that 2D hybrid metal halide materials may prove superior to the current conventional semiconductor materials for THz applications, which require sophisticated deposition approaches that are more susceptible to defects.
“We hope that our research will launch a promising testbed for designing a wide variety of low-dimensional hybrid metal halide materials for future solution-based spintronic and spin-optoelectronic applications.”
Engineers have created a new type of battery that weaves two promising battery sub-fields into a single battery. This battery uses both a solid-state electrolyte and an all-silicon anode, making it a silicon all-solid-state battery.
An initial round of tests showed that the new battery is safe, long lasting and energy dense, and thus holds promise for a wide range of applications, from grid storage to electric vehicles. Nanoengineers at the University of California (UC) San Diego led the research, in collaboration with researchers at LG Energy Solution (LGES). They report the novel battery in a paper in Science.
Silicon anodes are famous for their energy density, which is 10 times greater than the graphite anodes most often used in today's commercial lithium-ion batteries. On the other hand, silicon anodes are infamous for how they expand and contract as the battery charges and discharges, and how liquid electrolytes cause them to degrade.
These challenges have kept all-silicon anodes out of commercial lithium-ion batteries, despite their tantalizing energy density. The new work offers a promising path forward for all-silicon-anodes, thanks to the right electrolyte.
"With this battery configuration, we are opening a new territory for solid-state batteries using alloy anodes such as silicon," said Darren Tan, lead author of the paper, who recently completed his chemical engineering PhD at the UC San Diego Jacobs School of Engineering.
Next-generation, solid-state batteries with high energy densities have always relied on metallic lithium as the anode. But metallic lithium places restrictions on battery charge rates and requires elevated temperatures (usually 60°C or higher) during charging. The silicon anode overcomes these limitations, allowing much faster charge rates at room to low temperatures while maintaining high energy densities.
The team demonstrated a laboratory-scale full cell that delivers 500 charge and discharge cycles with 80% capacity retention at room temperature. This represents exciting progress for both the silicon anode and solid-state battery communities.
Silicon anodes are not new. For decades, scientists and battery manufacturers have looked to silicon as an energy-dense material to mix into, or completely replace, conventional graphite anodes in lithium-ion batteries. Theoretically, silicon offers approximately 10 times the storage capacity of graphite. In practice however, lithium-ion batteries with silicon added to the anode typically suffer from real-world performance issues: in particular, the number of times the battery can be charged and discharged while maintaining performance is not high enough.
Much of the problem is caused by the interaction between silicon anodes and the liquid electrolytes they are paired with. The situation is complicated by the large volume expansion of silicon particles during charge and discharge, which results in severe capacity losses over time.
“As battery researchers, it's vital to address the root problems in the system. For silicon anodes, we know that one of the big issues is the liquid electrolyte interface instability," said UC San Diego nanoengineering professor Shirley Meng, corresponding author of the Science paper and director of the Institute for Materials Discovery and Design at UC San Diego. “We needed a totally different approach.”
So the UC San Diego-led team took a different approach: they eliminated the carbon and the binders that are commonly used with all-silicon anodes. In addition, they used micro-silicon, which is less processed and less expensive than the nano-silicon that is usually used.
In addition to removing all the carbon and binders from the anode, the team also removed the liquid electrolyte, replacing it with a sulfide-based solid electrolyte. Their experiments showed that this solid electrolyte is extremely stable in batteries with all-silicon anodes.
"This new work offers a promising solution to the silicon anode problem, though there is more work to do," said Meng, "I see this project as a validation of our approach to battery research here at UC San Diego. We pair the most rigorous theoretical and experimental work with creativity and outside-the-box thinking. We also know how to interact with industry partners while pursuing tough fundamental challenges."
Past efforts to commercialize silicon alloy anodes mainly focused on silicon-graphite composites, or on combining nano-structured particles with polymeric binders. But they still struggled with poor stability.
By swapping out the liquid electrolyte for a solid electrolyte, and at the same time removing the carbon and binders from the silicon anode, the researchers avoided a series of related challenges that arise when anodes become soaked in the organic liquid electrolyte as the battery operates.
At the same time, by eliminating the carbon in the anode, the researchers significantly reduced the interfacial contact (and unwanted side reactions) with the solid electrolyte, avoiding the continuous capacity loss that typically occurs with liquid-based electrolytes. This two-part move allowed the researchers to fully reap the benefits of the low cost, high energy and environmentally benign properties of silicon.
“The solid-state silicon approach overcomes many limitations in conventional batteries,” said Tan. “It presents exciting opportunities for us to meet market demands for higher volumetric energy, lowered costs and safer batteries, especially for grid energy storage.”
Sulfide-based solid electrolytes were often believed to be highly unstable. However, this was based on the traditional thermodynamic interpretations used for liquid electrolyte systems, which did not account for the excellent kinetic stability of solid electrolytes. The team saw an opportunity to utilize this counterintuitive property to create a highly stable anode.
Tan is the CEO and co-founder of a start-up, UNIGRID Battery, that has licensed the technology for these silicon all-solid-state batteries. In parallel, related fundamental work will continue at UC San Diego, including additional research collaboration with LGES.
“LG Energy Solution is delighted that the latest research on battery technology with UC San Diego made it onto the journal of Science, a meaningful acknowledgement,” said Myung-hwan Kim, president and chief procurement officer at LGES. “With the latest finding, LG Energy Solution is much closer to realizing all-solid-state battery techniques, which would greatly diversify our battery product line-up.
“As a leading battery manufacturer, LGES will continue its effort to foster state-of-the-art techniques in leading research of next-generation battery cells.”
To this end, LGES said it plans to further expand its solid-state battery research collaboration with UC San Diego.
Most people are familiar with computed tomography for medicine: a part of the body is X-rayed from all sides to produce a three-dimensional (3D) image, from which sectional images can be created for diagnosis.
This method can also be very useful for material analysis, non-destructive quality testing and the development of new functional materials. But examining such materials at high spatial resolution and in the shortest possible time requires the particularly intense X-ray light of a synchrotron radiation source. Using a synchrotron beam, even rapid changes and processes in material samples can be imaged, making it possible to acquire three-dimensional images in a very short time sequence.
A team of researchers from Helmholtz-Zentrum Berlin (HZB) in Germany, led by Francisco Garcia Moreno, has been working on this kind of fast computed tomography of materials, in conjunction with colleagues from the Swiss Light Source (SLS) at the Paul Scherrer Institute (PSI) in Switzerland. Two years ago, they achieved a record-breaking 200 tomograms per second by developing a new method called fast-imaging tomography.
Now, the researchers have achieved a new world record – 1000 tomograms per second – allowing them to record even faster processes in materials and during manufacturing. As they report in a paper in Advanced Materials, this is achieved without any major compromises in other parameters: the spatial resolution is still very good, at several micrometres; the field of view is several square millimetres; and continuous recording periods for up to several minutes are possible.
To achieve this world record, the researchers placed the sample on a high-speed rotary table developed in-house, whose angular speed can be perfectly synchronized with the camera's acquisition speed. "We used particularly lightweight components for this rotary table so that it can reach 500 Hertz rotation speed stably," says Moreno.
At the TOMCAT beamline at the SLS, which specializes in time-resolved X-ray imaging, PSI physicist Christian Schlepütz used a new high-speed camera and special optics. "This increases the sensitivity very significantly, so that we can take 40 2D projections in one millisecond, from which we create a tomogram," Schlepütz explains. With the planned SLS2.0 upgrade, even faster measurements with higher spatial resolution should be possible from 2025.
The acquisition of 1000 3D data sets per second – over a period of minutes – generates a huge data stream, which was initially stored at the PSI. Paul Kamm at HZB was responsible for the further processing and quantitative evaluation of these data. The reconstruction of the raw data into 3D images was carried out on the high-performance computers at PSI, and the results were then transferred to HZB for further analysis.
The researchers demonstrated the power of this super-fast version of computed tomography on various material samples. They recorded images of the extremely rapid changes during the burning of a sparkler, the formation of dendrites during the solidification of casting alloys, and the growth and coalescence of bubbles in a liquid metal foam. Such metal foams based on aluminium alloys are being investigated as lightweight materials, for use in constructing electric cars, for example. The morphology, size and cross-linking of the bubbles are important to achieve the desired mechanical properties such as strength and stiffness in large components.
"This method opens a door for the non-destructive study of fast processes in materials, which is what many research groups and also industry have been waiting for," says Moreno.
– We’re becoming an attractive place to work for researchers from Poland and abroad – says Prof. Agnieszka Wojciechowska, coordinator of the team for the implementation of the European Human Resources Strategy for Resources Strategy for Researchers.
Injection molding specialist Engel Mexico has appointed Emilio López as its new managing director (MD), succeeding Peter Auinger, who retired in September 2021.
‘We are delighted to have signed up a highly experienced expert for our strategically important market of Mexico – someone who is familiar with the cultural environments of both Latin America and Europe,’ said Dr.Christoph Steger, CSO of ENGEL Austria. ‘In future, Mexico will be a key service hub for ENGEL customers in Latin America.’
According to the company, Mexico is its largest Latin American market with demand rising for all-electric injection moulding machines and dual-platen large machines.
This story uses material from Engel, with editorial changes made by Materials Today.
Vertical Aerospace has appointed Harry Holt as its chief operating officer (COO).
According to the company, Holt previously worked as chief people officer at Rolls-Royce and served as a member of the executive team. Previously, he led Rolls-Royce’s nuclear business in support of the UK Royal Navy’s submarine program and civil nuclear power markets worldwide, as well as previously being group operations strategy director.
As COO, Harry will focus on implementing Vertical’s operational and manufacturing strategy and government relations, the company said.
‘It is clear that the VA-X4 is going to revolutionise short-haul air travel,’ said Harry Holt. ‘I am proud have the opportunity to play a part in transforming aviation while also delivering on our objective to achieve a net zero economy.’
This story uses material from Vertical, with editorial changes made by Materials Today.
3D printing company America Makes has postponed its in-person Members Meeting and Exchange (MMX) event, scheduled for 19–20 October 2021 in Canfield, Ohio.
The meetings will now take place virtually from 1–2 December, 2021.
‘We know that after 18 months of virtual settings we were all looking forward to being back together as a community,’ the organization said. ‘However, the health and safety of our attendees, presenters, and team remains our top priority.’
This story uses material from America Makes, with editorial changes made by Materials Today.
AOC has announced a price increase of $0.10/lb for all its products sold in the USA, Canada, Mexico and Latin America.
It has also increased prices by €100-200 per ton (depending on resin chemistry) for its range of unsaturated polyester (UPR) and epoxy vinyl ester (VE) resins, and sizings and binders products sold in Europe, Middle East and Africa.
This increase is due to continuing and escalation of costs for key raw material ingredients and freight, the company said. ‘In addition, the availability of key raw materials from our contract suppliers has been severely hampered and we are continuing to have to resort to other, significantly more expensive, sources, said Fons Harbers, VP at AOC.
This story uses material from AOC, with editorial changes made by Materials Today.
"Gallium nitride (GaN)-on-diamond shows promise as a next-generation semiconductor material"Jianbo Liang
Scientists from Osaka City University, Tohoku University, Saga University, and Adamant Namiki Precision Jewel Co in Japan have developed a gallium nitride (GaN)-on-diamond semiconductor material that can withstand heat of up to 1,000?, in research that could bring about the next generation of highly conductive semiconductors and high-power devices.
GaN-on-diamond offers potential as an innovative semiconductor material due to the wide bandgap of both materials, which allows for high conductivity, while the high thermal conductivity of diamond makes it an excellent heat-spreading substrate. As reported in the journal Advanced Materials [Liang et al. Adv. Mater. (2021) DOI: 10.1002/adma.202104564], this is the first time that direct bonding of GaN and diamond has been achieved.
Increasing the power of electronic devices is limited by the need to identify highly conductive semiconductors that can withstand the high temperature processes required for their manufacture. Previous attempts at producing a GaN-on-diamond structure by combining the two components with some form of transition layer were constrained by this layer interfering with diamond’s thermal conductivity.
However, by fusing the two elements together without an intermediate layer, called “wafer direct bonding”, this problem can be overcome, although to develop a sufficiently high bonding strength such a structure usually needs to be heated to extremely high degrees in a post-annealing process. This can produce cracks in dissimilar materials due to the thermal expansion mismatch.
The team had previously used surface activated bonding (SAB) to fabricate interfaces with diamond at room temperature to provide high thermal stability. Applying the method to GaN and diamond produced bonding was stable even when heated to 1,000?. SAB offers such strong bonds between different materials at room temperature by atomically cleaning and activating the bonding surfaces when brought into contact with each other.
After applying SAB to the GaN-on-diamond material, the team tested the stability the bonding site, or heterointerface. On increasing the annealing temperatures, a decrease in the layer thickness was shown due to a direct conversion of amorphous carbon into diamond at the bonding interface. After annealing at 1,000?, the layer decreased in size, which suggests the intermediate layer can be fully removed by optimizing the annealing process.
With no peeling being observed at the heterointerface after annealing, the findings indicate the GaN/diamond heterointerface can withstand harsh fabrications processes, with the temperature rise in GaN transistors being suppressed by a factor of four. It is expected that the potential applications of such transistors in high-power applications such as radars and inverters will increase. The team now hope to improve the device’s performance and simplify its heat dissipation structure to make the system smaller and lighter.
Researchers at Rutgers University, together with their collaborators, have found that learning – a universal feature of intelligence in living beings – can be mimicked in nickel oxide, a discovery that could inspire new algorithms for artificial intelligence (AI). The researchers report their work in a paper in the Proceedings of the National Academy of Sciences.
One of the fundamental characteristics of humans is their ability to continuously learn from and adapt to changing environments. But until recently, AI has been narrowly focused on emulating human logic. Now, researchers are looking to mimic human cognition in devices that can learn, remember and make decisions the way a human brain does.
Emulating such features in the solid state could inspire new algorithms in AI and neuromorphic computing that would have the flexibility to address uncertainties, contradictions and other aspects of everyday life. Neuromorphic computing mimics the neural structure and operation of the human brain, in part by building artificial nerve systems to transfer electrical signals that mimic brain signals.
To mimic learning, researchers from Rutgers University, Purdue University and other institutions studied how the electrical conductivity of nickel oxide, a special type of insulating material, responded when its environment was changed repeatedly over various time intervals.
“The goal was to find a material whose electrical conductivity can be tuned by modulating the concentration of atomic defects with external stimuli such as oxygen, ozone and light,” explained Subhasish Mandal, a postdoctoral associate in the Department of Physics and Astronomy at Rutgers-New Brunswick. “We studied how this material behaves when we dope the system with oxygen or hydrogen, and most importantly, how the external stimulation changes the material's electronic properties.”
The researchers found that when the gas stimulus changed rapidly, the material couldn’t respond in full. It stayed in an unstable state in either environment and its response began to decrease. When the researchers introduced a noxious stimulus such as ozone, the material began to respond more strongly only to decrease again.
“The most interesting part of our results is that it demonstrates universal learning characteristics such as habituation and sensitization that we generally find in living species,” Mandal said. “These material characteristics in turn can inspire new algorithms for artificial intelligence. Much as collective motion of birds or fish have inspired AI, we believe collective behavior of electrons in a quantum solid can do the same in the future.
“The growing field of AI requires hardware that can host adaptive memory properties beyond what is used in today’s computers. We find that nickel oxide insulators, which historically have been restricted to academic pursuits, might be interesting candidates to be tested in future for brain-inspired computers and robotics.”
This story is adapted from material from Rutgers 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.
The EPMA has set the date for a two-day metal injection molding (MIM) conference located at the headquarters of Arburg GmbH in Loßburg, Germany.
The event, taking place from 27-28 October 2021, will include interactive sessions on practical problems and solutions, with discussion among participants. While suggested topics are digitisation and simulation, and sustainability, participants can also bring other practical questions to be discussed in the workshop ‘campfire meetings’, the EPMA said.
‘MIM is gaining market because of the wide range of alloys available with excellent properties, combined with reproducible tolerances, precision, surface roughness and high-quality finish, and a definite advantage in large series where tooling costs are less critical,’ a press release said. ‘But improvement needs to continue, and the challenges and opportunities must be tackled and exploited, respectively.’
The number of participants is limited to 50 and the deadline to register is 13 October. Fees are €700 for EPMA non-members and €500 for members, end-users and universities.
This story uses material from the EPMA, with editorial changes made by Materials Today.
Hard materials specialist Hyperion Materials has acquired GLE Precision, a Michigan-based manufacturer that makes high-precision small parts and extreme surface finishes and tolerances.
GLE, founded in 1961 as a manufacturer of plug and ring gages, precision grinds tungsten carbide, ceramic and other hard materials, and produces custom parts.
‘GLE possesses unique knowledge in the manufacture of precision tooling, dies, components and other special wear parts,’ said Ron Voigt, CEO of Hyperion. ‘Together we can greatly expand the products and services we offer to a more diverse set of customers, especially those who manufacture high-value products in the waterjet cutting, semiconductor, fiber optics, medical and aerospace industries.’
This story uses material from Hyperion, with editorial changes made by Materials Today.
Trelleborg reportedly plans to extend its manufacturing operations in Russia, Vietnam, Japan, and Morocco, the group’s first fully owned production facilities in these countries.
The company says that it has invested just under SEK 300 million, allocated over five years, to develop the new facilities. When the facilities are fully operational in 2026, they are expected to have just over 300 employees.
‘Trelleborg’s success is based on our ability to combine a strongly decentralized and local organization with the competence and financial strength of a global company,’ said Peter Nilsson, president and CEO of Trelleborg Group. ‘To do this we must be close to our customers and be able to grow alongside them, and over time also develop other local customer relationships that may become global.’
Trelleborg Sealing Solutions will be located in Russia and Vietnam, while Trelleborg Industrial Solutions will begin manufacture in Japan and Morocco, the company said.
This story uses material from Trelleborg, with editorial changes made by Materials Today.
Metal reclamation company 6K Additive has launched a range of refractory metal powders for 3D printing. According to the company, it has spheroidized the full spectrum of refractory powders including tantalum, niobium and molybdenum. 6K Additive says that its UniMelt system is the world's only microwave production-scale plasma system.
‘The uniqueness of 6K's UniMelt microwave plasma process […] has allowed us to manufacture production scale volumes for many of the refractory powders like tungsten and tungsten/rhenium,’ said Frank Roberts, 6K Additive president.
Recently the company supplied tungsten-rhenium powder to produce a non-eroding throat insert for a solid rocket motor nozzle, an application which requires high-temperature, high-strength materials, according to Joe Sims, director of Quadrus, which made the nozzle.
This story uses material from 6K, with editorial changes made by Materials Today.
Metallurgy company SSI Sintered Specialties has reportedly acquired two metal binder jetting machines from 3D printing specialist ExOne.
According to the company, SSI will use the InnoventPro 3L for material and application development, and the X1 160Pro for volume production.
The two printers will be located at the company’s headquarters in Janesville, Wisconsin, which also houses the world’s largest installed capacity of high temperature sintering furnaces and post-processing technology, according to ExOne. SSI also has capabilities in press and sinter powder metallurgy and metal injection molding (MIM).
This story uses material from ExOne, with editorial changes made by Materials Today.
Almost 2 thousand candidates from abroad wanted to study this year at Wrocław Tech, which is a record number of applications for admission to our university. Some 550 foreign people have just inaugurated the academic year.
Over 21 thousand students have started their academic year at Wrocław University of Science and Technology today. During the celebrative event, the title of doctor honoris causa of our university was awarded to Rafał Dutkiewicz, PhD, Eng.
Prof. Gerard Mourou, winner of the 2018 Nobel Prize in Physics, is to be awarded an honorary doctorate by Wrocław University of Science and Technology, following the university Senate’s decision made on Thursday.
On November 15 the first winner of the Stanisław Lem European Research Prize will be announced. The prize will be awarded to a young scientist whose research has the potential to positively impact the future of our civilisation.
The Polish and English Language Center for Foreigners operating in the Department of Foreign Languages is among ten universities in Poland that have been accredited by the National Agency for Academic Exchange.
Prof. Arkadiusz Wójs, Rector of Wrocław University of Science and Technology, received the title of Honorary Professor of Óbuda University in Budapest. The ceremony was combined with the inauguration of the new academic year.
Abstract: How do scientific ideas become market products? There is probably no single pathway for such transformation. And yet, there are certain similarities in the way how advanced materials evolve from laboratory studies to being used in technology. Common steps in such progress are the enhancement of useful properties, development of the production methods, creation of industrially-relevant modification of the material itself and its fabrication process. The reason in the emergent similarities in the pathway to market is the established relation between materials supplier and the final product manufacturers. A dramatic role in such relations is played by industrial standards. The later can help, but also, if incorrectly developed, can stumble the final product development. We will study the process of commercialisation of graphene, its transformation to commodity and the emerging graphene standardisation efforts.
Abstract: Microneedle (MN) patches consisting of miniature needles have emerged as a promising tool to perforate the stratum corneum and translocate biomolecules into the dermis in a minimally invasive manner. Stimuli-responsive MN patches represent emerging drug delivery systems that release cargos on-demand as a response to internal or external triggers. In this review, a variety of stimuli-responsive MN patches for controlled drug release are introduced, covering the mechanisms of action toward different indications. Future opportunities and challenges with respect to clinical translation are also discussed.
Abstract: Reversible hydrogen absorption/desorption, the very fundamental property of metal hydrides (MHs), can be utilized to innovate the water splitting process. Spontaneous hydrogen absorption by a MH electrode shifts the water reduction potential to 0.3?V above the reversible hydrogen electrode. Then, the absorbed hydrogen can be released to give H2 by thermal dehydrogenation at mild temperature below 70?°C by utilizing low grade heat. The MH mediated water splitting combines the electrochemical hydrogen absorption in Ni-MH batteries and the thermal dehydrogenation in gas phasehydrogen storage, which significantly reduces the electrical energy consumption for water splitting up to 25?kJ (mol?H2)−1 compared to an ideal hydrogen evolution catalyst and also automatically leads to decoupled H2/O2 generation. The advantages and mechanisms of the MH mediated water splitting are demonstrated by MH electrodes with surface Pd coating.
Abstract: Proteases are multi-functional proteolytic enzymes that have complex roles in human health and disease. Therefore, the development of protease biosensors can be beneficial to global health applications. To this end, we developed Advanced proteoLytic detector PolyHydroxyAlkanoates (AL-PHA) beads – a library of over 20 low-cost, biodegradable, bioplastic-based protease biosensors. Broadly, these biosensors utilise PhaC-reporter fusion proteins that are bound to microbially manufactured polyhydroxyalkanoate beads. In the presence of a specific protease, superfolder green fluorescent reporter proteins are cleaved from the AL-PHA beads – resulting in a loss of bead fluorescence. The Tobacco Etch Virus (TEV) AL-PHA biosensor detected the proteolytic activity of at least 1.85?pM of AcTEV. AL-PHA beads were also engineered to detect cercarial elastase from Schistosoma mansoni-derived cercarial transformation fluid (SmCTF) samples, as well as cancer-associated metalloproteinases in extracellular vesicle and cell-conditioned media samples. We envision that AL-PHA beads could be further developed for use in resource-limited settings.