Material Science News and Discussions

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Researchers create photonic materials for powerful, efficient light-based computing

by Robert Wells, University of Central Florida

University of Central Florida researchers are developing new photonic materials that could one day help enable low power, ultra-fast, light-based computing.

The unique materials, known as topological insulators, are like wires that have been turned inside out, where the current runs along the outside and the interior is insulated.

Topological insulators are important because they could be used in circuit designs that allow for more processing power to be crammed into a small space without generating heat, thus avoiding the overheating problem today's smaller and smaller circuits face.
https://phys.org/news/2022-05-photonic- ... based.html
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Researchers unveil a secret of stronger metals
https://phys.org/news/2022-05-unveil-se ... etals.html
by David L. Chandler, Massachusetts Institute of Technology
For the first time, researchers have described how the tiny crystalline grains that make up most solid metals actually form. Understanding this process, they say, could theoretically lead to ways of producing stronger, lighter versions of widely used metals such as aluminum, steel and titanium. Credit: Massachusetts Institute of Technology

Forming metal into the shapes needed for various purposes can be done in many ways, including casting, machining, rolling, and forging. These processes affect the sizes and shapes of the tiny crystalline grains that make up the bulk metal, whether it be steel, aluminum or other widely used metals and alloys.
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Transparency on demand: A novel process can render artificial materials transparent or even entirely invisible
https://phys.org/news/2022-05-transpare ... arent.html
by Sissy Gudat, University of Rostock
Space, the final frontier. The starship Enterprise pursues its mission to explore the galaxy, when all communication channels are suddenly cut off by an impenetrable nebula. In many episodes of the iconic TV series, the valiant crew must "tech the tech" and "science the science" within just 45 minutes of airtime in order to facilitate their escape from this or a similar predicament before the end credits roll. Despite spending a significantly longer time in their laboratories, a team of scientists from the University of Rostock has succeeded in developing an entirely new approach for the design of artificial materials that can transmit light signals without any distortions by means of precisely tuned flows of energy. They have published their results in Science Advances.

"When light spreads in an inhomogeneous medium, it undergoes scattering. This effect quickly transforms a compact, directed beam into a diffuse glow, and is familiar to all of us from summer clouds and autumn fog alike," Professor Alexander Szameit of the Institute for Physics at the University of Rostock describes the starting point of his team's considerations. Notably, it is the microscopic density distribution of a material that dictates the specifics of scattering. Szameit continues, "The fundamental idea of induced transparency is to take advantage of a much lesser-known optical property to clear a path for the beam, so to speak."

This second property, known in the field of photonics under the arcane title of non-Hermiticity, describes the flow of energy, or, more precisely, the amplification and attenuation of light. Intuitively, the associated effects may seem undesirable—particularly the fading of a light beam due to absorption would seem highly counterproductive to the task of improving signal transmission. Nevertheless, non-Hermitian effects have become a key aspect of modern optics, and an entire field of research strives to harness the sophisticated interplay of losses and amplification for advanced functionalities.
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Can we make graphite from coal? Researchers start by finding new carbon solid

by Ohio University
https://phys.org/news/2022-06-graphite- ... solid.html
As the world's appetite for carbon-based materials like graphite increases, Ohio University researchers presented evidence this week for a new carbon solid they named "amorphous graphite."

Physicist David Drabold and engineer Jason Trembly started with the question, "Can we make graphite from coal?"

"Graphite is an important carbon material with many uses. A burgeoning application for graphite is for battery anodes in lithium-ion batteries, and it is crucial for the electric vehicle industry—a Tesla Model S on average needs 54 kg of graphite. Such electrodes are best if made with pure carbon materials, which are becoming more difficult to obtain owing to spiraling technological demand," they write in their paper, "Ab initio simulation of amorphous graphite," that published today in Physical Review Letters.

"Ab initio" means "from the beginning," and their work pursues novel paths to synthetic forms of graphite from naturally occurring carbonaceous material. What they found, with several different calculations, was a layered material that forms at very high temperatures (about 3000 degrees Kelvin). Its layers stay together due to the formation of an electron gas between the layers, but they're not the perfect layers of hexagons that make up ideal graphene. This new material has plenty of hexagons, but also pentagons and heptagons. That ring disorder reduces the electrical conductivity of the new material compared with graphene, but the conductivity is still high in the regions dominated largely by hexagons.
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Scientists develop antimicrobial, plant-based food wrap designed to replace plastic
https://phys.org/news/2022-06-scientist ... astic.html
by Rutgers University
Aiming to produce environmentally friendly alternatives to plastic food wrap and containers, a Rutgers scientist has developed a biodegradable, plant-based coating that can be sprayed on foods, guarding against pathogenic and spoilage microorganisms and transportation damage.

The scalable process could potentially reduce the adverse environmental impact of plastic food packaging as well as protect human health.

"We knew we needed to get rid of the petroleum-based food packaging that is out there and replace it with something more sustainable, biodegradable and nontoxic," said Philip Demokritou, director of the Nanoscience and Advanced Materials Research Center, and the Henry Rutgers Chair in Nanoscience and Environmental Bioengineering at the Rutgers School of Public Health and Environmental and Occupational Health Sciences Institute. "And we asked ourselves at the same time, 'Can we design food packaging with a functionality to extend shelf life and reduce food waste while enhancing food safety?'''

Demokritou added, "And what we have come up with is a scalable technology, which enables us to turn biopolymers, which can be derived as part of a circular economy from food waste, into smart fibers that can wrap food directly. This is part of new generation, 'smart' and 'green' food packaging."
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Cooking up a conductive alternative to copper with aluminum
https://phys.org/news/2022-06-cooking-a ... minum.html
by Alexandra Freibott, Pacific Northwest National Laboratory
In the world of electricity, copper is king—for now. That could change with new research from Pacific Northwest National Laboratory (PNNL) that is serving up a recipe to increase the conductivity of aluminum, making it economically competitive with copper. This research opens the door to experiments that—if fully realized—could lead to an ultra-conductive aluminum alternative to copper that would be useful in markets beyond transmission lines, revolutionizing vehicles, electronics, and the power grid.

"What if you could make aluminum more conductive—even 80% or 90% as conductive as copper? You could replace copper and that would make a massive difference because more conductive aluminum is lighter, cheaper, and more abundant," said Keerti Kappagantula, PNNL materials scientist and co-author on the research. "That's the big picture problem that we're trying to solve."

Copper vs. aluminum

Copper demand is fast outpacing its current availability, driving up its cost. Copper is a great electrical conductor—it's used in everything from handheld electronics to underwater transmission cables that power the internet—but there's no escaping the fact that copper is becoming less available and more expensive. These challenges are only expected to get worse with the rising number of electric vehicles (EVs), which need twice as much copper as traditional vehicles. Plus, copper is heavy, which drives down EV efficiency.

Aluminum is just one-third the price and weight of copper, but it is only about 60% as conductive. Aluminum's relatively low conductivity can be a limitation in some real-world applications.
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A ceramic aerogel made with nanocrystals and embedded in a matrix for use in thermal insulation applications
https://phys.org/news/2022-07-ceramic-a ... atrix.html
by Bob Yirka , Phys.org
A team of researchers at the Harbin Institute of Technology, in China, working with a colleague in the U.S., has developed a new kind of aerogel for use in flexible thermal insulation material applications. In their paper published in the journal Nature, the group describes how they made their aerogel and how well it worked when extreme heat was applied.

Prior work has shown that aerogels made using ceramic materials work very well as thermal insulators—their very low densities have very low thermal conductivity. But such materials are brittle, making them unavailable for use in flexible material applications, such as suits for firefighters. They also tend to break down when exposed to very high temperatures. In this new effort, the researchers have developed a method for making a ceramic based aerogel that can be used in flexible applications and also does not break down when exposed to very high temperatures.

To create their aerogel, the researchers took a novel approach—they pushed a zirconium-silicon precursor, using a plastic syringe, into a chamber with turbulent airflow—an electrospinning approach that produced a ceramic material that resembled cotton candy. They then folded the resulting material into a zig-zag pattern and heated it to 1100° C. Heating it in such a way changed the texture of the material from a glassy state to a nanocrystal. Study of the resulting material using a spectroscope showed that their approach had resulted in the creation of a material with nanocrystalline bits embedded in an amorphous zircon matrix—a flexible aerogel made using a ceramic that was not prone to breaking down under high temperatures.
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Characterizing the materials for next-generation quantum computers with nonlinear optical spectroscopy
https://phys.org/news/2022-07-character ... inear.html
by Universität Hamburg

Researchers at the Department of Physics and the Cluster of Excellence "CUI: Advanced Imaging of Matter" of Universität Hamburg and the University of California at Irvine have recently proposed a new way to characterize topological superconductors by means of multi-THz-pulse experiments.

This opens a pathway to unambiguously identifying predicted exotic states of matter and can aid in the design of novel materials for future devices that carry and process quantum information.

Scientists around the world are working to build scalable quantum computers based on solid-state matter. One such class of materials are topological superconductors. They are purported to host a particular kind of collective quantum state, the non-abelian anyons in the form of Majorana fermions at their boundaries. By shuffling these quasiparticles around in networks of quantum wires, researchers can construct logical quantum gates, the building blocks of quantum computers.
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Scientists develop durable material for flexible artificial muscles
https://phys.org/news/2022-07-scientist ... icial.html
by University of California, Los Angeles

UCLA materials scientists and colleagues at the nonprofit scientific research institute SRI International have developed a new material and manufacturing process for creating artificial muscles that are stronger and more flexible than their biological counterparts.

"Creating an artificial muscle to enable work and detect force and touch has been one of the grand challenges of science and engineering," said Qibing Pei, a professor of materials science and engineering at the UCLA Samueli School of Engineering and the corresponding author of a study recently published in Science.

In order for a soft material to be considered for use as an artificial muscle, it must be able to output mechanical energy and remain viable under high-strain conditions—meaning it does not easily lose its form and strength after repeated work cycles. While many materials have been considered contenders for making artificial muscles, dielectric elastomers (DE)—lightweight materials with high elastic energy density—have been of special interest because of their optimal flexibility and toughness.
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Designer materials to keep plastic out of landfills
https://phys.org/news/2022-07-materials ... fills.html
by Alison Hatt, Lawrence Berkeley National Laboratory
Scientists have designed a new material system to overcome one of the biggest challenges in recycling consumer products: mixed-plastic recycling. Their achievement will help enable a much broader range of fully recyclable plastic products and brings into reach to an efficient circular economy for durable goods like automobiles.

We generate staggering quantities of plastic and plastic-containing products each year, but only a tiny fraction of that plastic can be recovered and used to manufacture products of similar quality. That's because most products, from food-packaging films and single-use bags to sneakers and electronics, are made from mixtures of different plastics, and once they are mixed, those plastics can't be recovered and used to make new bags or sneakers. Instead, most of it ends up in landfills, incinerators, or oceans.

A team of scientists from Lawrence Berkeley National Laboratory (Berkeley Lab) are tackling the mixed-plastic challenge using a custom-designed material called polydiketoenamine (PDK), a new type of plastic they developed to be recycled efficiently and indefinitely, providing a low-carbon manufacturing solution for plastic products that never have to end up in a landfill.
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