Material Science News and Discussions

weatheriscool
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Engineers develop inexpensive, scalable method to make metamaterials that manipulate microwave energy

by Tufts University
https://techxplore.com/news/2021-06-ine ... owave.html
Engineers at Tufts University have developed new methods to more efficiently fabricate materials that behave in unusual ways when interacting with microwave energy, with potential implications for telecommunications, GPS, radar, mobile devices, and medical devices. Known as metamaterials, they are sometimes referred to as "impossible materials" because they could, in theory, bend energy around objects to make them appear invisible, concentrate the transmission of energy into focused beams, or have chameleon like abilities to reconfigure their absorption or transmission of different frequency ranges.

The innovation, described today in Nature Electronics, constructs the metamaterials using low-cost inkjet printing, making the method widely accessible and scalable while also providing benefits such as the ability to be applied to large conformable surfaces or interface with a biological environment. It is also the first demonstration that organic polymers can be used to electrically "tune" the properties of the metamaterials.
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Yuli Ban
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Tougher Than Kevlar and Steel: Ultralight Material Withstands Supersonic Microparticle Impacts
The new carbon-based material could be a basis for lighter, tougher alternatives to Kevlar and steel.

A new study by engineers at MIT, Caltech, and ETH Zürich shows that “nanoarchitected” materials — materials designed from precisely patterned nanoscale structures — may be a promising route to lightweight armor, protective coatings, blast shields, and other impact-resistant materials.

The researchers have fabricated an ultralight material made from nanometer-scale carbon struts that give the material toughness and mechanical robustness. The team tested the material’s resilience by shooting it with microparticles at supersonic speeds, and found that the material, which is thinner than the width of a human hair, prevented the miniature projectiles from tearing through it.

The researchers calculate that compared with steel, Kevlar, aluminum, and other impact-resistant materials of comparable weight, the new material is more efficient at absorbing impacts.

“The same amount of mass of our material would be much more efficient at stopping a projectile than the same amount of mass of Kevlar,” says the study’s lead author, Carlos Portela, assistant professor of mechanical engineering at MIT.
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Engineers at MIT, Caltech, and ETH Zürich find “nanoarchitected” materials designed from precisely patterned nanoscale structures (pictured) may be a promising route to lightweight armor, protective coatings, blast shields, and other impact-resistant materials. Credit: Courtesy of the researchers
And remember my friend, future events such as these will affect you in the future
weatheriscool
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Research team shows complex, 3D-printed schwarzites withstand pressure when coated
https://phys.org/news/2021-07-team-comp ... ssure.html
by Rice University
A thin shell of soft polymer can help keep knotty ceramic structures from shattering, according to materials scientists at Rice University.

Ceramics made with 3D printers crack under stress like any plate or bowl. But covered in a soft polymer cured under ultraviolet light, the same materials stand a far better chance of keeping their structural integrity, much like a car windshield's treated glass is less likely to shatter.

The research at Rice's Brown School of Engineering, which appears in Science Advances, demonstrates the concept on schwarzites, complex lattices that for decades existed only as theory but can now be made with 3D printers. With added polymers, they come to resemble structures found in nature like seashells and bones that consist of hardened platelets in a biopolymer matrix.
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Solving the plastic shortage with a new chemical catalyst
https://phys.org/news/2021-07-plastic-s ... alyst.html
by University of Michigan
In a year that has already battered manufacturing supply chains, yet another shortage is complicating manufacturers' and consumers' lives: plastics, and the food packaging, automotive components, clothing, medical and lab equipment and countless other items that rely on them.

But a new chemical catalyst developed at the University of Michigan could enable the production of more of the feedstock for the world's second-most widely used plastic. The feedstock, propylene, is used to make the plastic polypropylene—8 million tons of it each year.

The new catalyst, which can make propylene from natural gas, is at least 10 times more efficient than current commercial catalysts. And it lasts 10 times longer before needing regeneration. It is made of platinum and tin nanoparticles that are supported by a framework of silica.

"Industry has shifted over the years from petroleum feedstocks to shale gas," said Suljo Linic, the Martin Lewis Perl Collegiate Professor of Chemical Engineering at U-M and senior author on a paper published in Science. "So there has been a push to find a way to efficiently produce propylene from propane, a component of shale gas. This catalyst achieves that objective."
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3D-printable phase-change materials insulate buildings better at scale
By Michael Irving
July 12, 2021
https://newatlas.com/materials/3d-print ... nsulation/
Heating and cooling systems are some of the biggest energy guzzlers in use, so passive temperature control could be a good way to reduce emissions. Phase-change materials (PCMs) show promise for this, and now engineers at Texas A&M have developed a new PCM composite that can be 3D printed.

The name “phase-change materials” is pretty self-explanatory – these materials will switch between phases of matter as the temperature changes. One of the most promising applications for this technology is insulation: the PCM melts into a liquid as it absorbs heat, cooling its surroundings. As the ambient temperature cools, the material will solidify again, releasing its stored heat.

In the past, PCMs have been used in coffee cups to keep hot drinks hot, fabrics that keep wearers warm or cool as needed, liquid coatings that prevent frost build-up, and in building materials that better regulate indoor temperature. It’s that last one that the researchers on the new study wanted to improve.
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Researchers discover a 'layer hall effect' in a 2D topological Axion antiferromagnet
https://phys.org/news/2021-07-layer-hal ... gical.html
by Boston College

Researchers have discovered a "layer" Hall effect in a solid state chip constructed of antiferromagnetic manganese bismuth telluride, a finding that signals a much sought-after topological Axion insulating state, the team reports in the current edition of the journal Nature.

Researchers have been trying to find evidence of a topological Axion insulating (TAI) state and developed some candidate materials based on theoretical calculations. The layered Hall effect represents the first clear experimental evidence of the state, a feature bound by the laws of quantum physics, according to Boston College Assistant Professor of Physics Qiong Ma, a senior researcher on the project, which included 36 scientists from universities in the U.S., Japan, China, Taiwan, Germany, and India.
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Simple, inexpensive method for guarding carbon fiber
https://phys.org/news/2021-07-simple-in ... fiber.html
by Tiffany Lee, University of Nebraska-Lincoln
For the past 50 years, manufacturers have considered carbon fiber a dream material: Though individual fibers are thinner than a strand of human hair, they can be twisted together and fused with a matrix material to form a lightweight composite that is stronger than steel, twice as stiff and a good conductor of heat. And, unlike metals, the material doesn't crack over time. It's been used in a wide range of applications, including air and spacecraft, cars, buildings, medical devices and sports equipment.

But carbon fiber has a major drawback, said Husker engineer Yongfeng Lu, an expert in carbon materials. Under extreme temperatures—encountered routinely in the aerospace industry, for example—carbon fiber oxidizes, meaning it reacts with oxygen in the air and burns, just as wood does when combined with enough heat and oxygen. Oxidation quickly diminishes the dream-like qualities of carbon fiber, particularly its strength.

"One weakness of carbon fibers is that they are burned easily if you have high enough temperatures and oxygen present," said Lu, Lott Distinguished University Professor of electrical and computer engineering. "If we could make them non-flammable, so that they don't burn when exposed to fire, that would be exciting."
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Through the thin-film glass, researchers spot a new liquid phase
https://phys.org/news/2021-07-thin-film ... phase.html
by University of Pennsylvania
Research published in the Proceedings of the National Academy of Sciences describes a new type of liquid in thin films, which forms a high-density glass. Results generated in this study, conducted by researchers in Penn's Department of Chemistry, demonstrate how these glasses and other similar materials can be fabricated to be denser and more stable, providing a framework for developing new applications and devices through better design.

Glass is typically created through solidification, or falling out of equilibrium, of a liquid when it is cooled to a temperature where its motion arrests. The structure of a glass closely resembles the liquid phase, but its properties are similar to solids, akin to a crystal.

Glasses that are made into ultrathin, nanometer-scale films are widely used in applications such as OLED displays and optical fibers. But when these types of glasses are made into thin films, even at cold temperatures they behave more like a liquid, and the resulting material can be prone to droplet formation or crystallization, which limits the size of the smallest features that are possible.
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Metallic water created for the first time in golden experiment
By Michael Irving
July 28, 2021
https://newatlas.com/science/metallic-water-experiment/
Researchers have created metallic water for the first time. Through a very careful experimental setup, the team grew a thin layer of a gold-colored metallic water on the outside of a droplet of liquid metal.

It may be surprising for most people to find out that water is actually an insulator – at least when it’s perfectly pure. The stuff that comes out of the tap, however, is a well-known conductor of electricity, due to the salts and impurities it contains. But making pure water metallic, or conductive, has long been a scientific challenge.

But now, a team of researchers from 11 institutions around the world has pulled it off at the BESSY II facility in Berlin. The key to the breakthrough was to pair the water with an alkali metal, which are known to easily release electrons from the outer shells of their atoms.
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Metamaterials research challenges fundamental limits in photonics

by Cornell University
https://phys.org/news/2021-08-metamater ... onics.html
Cornell researchers are proposing a new way to modulate both the absorptive and the refractive qualities of metamaterials in real time, and their findings open intriguing new opportunities to control, in time and space, the propagation and scattering of waves for applications in various areas of wave physics and engineering.

The research published in the journal Optica, "Spectral causality and the scattering of waves," is authored by doctoral students Zeki Hayran and Aobo Chen, M.S. '19, along with their adviser, Francesco Monticone, assistant professor in the School of Electrical and Computer Engineering in the College of Engineering.

The theoretical work aims to expand the capabilities of metamaterials to absorb or refract electromagnetic waves. Previous research was limited to modifying either absorption or refraction, but the Monticone Research Group has now shown that if both qualities are modulated in real time, the effectiveness of the metamaterial can be greatly increased.
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