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Jun 13, 2020

Scientists Detect Surprise Structures Wrapped Around Earth’s Core

Posted by in category: materials

Blobs of hot, dense material that curl around Earth’s core are much more widespread than previous research suggests.

A new method of analysing earthquake data has found even more of the previously detected continent-sized zones at the boundary between the planet’s core and mantle.

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Jun 12, 2020

A reconfigurable ferroelectric field-effect transistor for frequency multiplication

Posted by in categories: computing, materials

Frequency multipliers, circuits that can produce signals with multiple frequencies, are essential components for a number of technological tools, particularly wireless communications systems. Most existing multipliers, however, are built using filtering and amplification circuits that are bulky and rapidly drain a lot of power.

Researchers at NaMLab in Germany have recently devised a single ferroelectric field-effect transistor that can serve both as a full-wave rectifier and frequency multiplier. The device they developed, presented in a paper published in Nature Electronics, is fully reconfigurable and energy-efficient, as it can be used in isolation, not requiring any additional circuits.

“Our institute (NaMLab) has been doing research on ferroelectric hafnium oxide (HfO2) since this material’s ferroelectric properties were discovered in 2007,” Halid Mulaosmanovic, one of the researchers who carried out the study, told TechXplore. “An attractive electronic device that can be made using this material is a ferroelectric field-effect transistor (FeFET), which resembles conventional logic transistors, but has a ferroelectric layer in the gate stack.”

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Jun 9, 2020

Erik Schlangen: A “self-healing” asphalt

Posted by in category: materials

Paved roads are nice to look at, but they’re easily damaged and costly to repair. Erik Schlangen demos a new type of porous, asphalt made of simple materials with an astonishing feature: When cracked, it can be “healed” by induction heating. (Filmed at TEDxDelft.)

TEDTalks is a daily video podcast of the best talks and performances from the TED Conference, where the world’s leading thinkers and doers give the talk of their lives in 18 minutes (or less). Look for talks on Technology, Entertainment and Design — plus science, business, global issues, the arts and much more.
Find closed captions and translated subtitles in many languages at http://www.ted.com/translate

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Jun 6, 2020

Inverse-designed spinodoid metamaterials

Posted by in category: materials

npj Computational Materials volume 6, Article number: 73 (2020) Cite this article.

Jun 5, 2020

A powder-metallurgy-based strategy toward three-dimensional graphene-like network for reinforcing copper matrix composites

Posted by in category: materials

Three-dimensional graphene network is a promising structure for improving both the mechanical properties and functional capabilities of reinforced polymer and ceramic matrix composites. However, direct application in a metal matrix remains difficult due to the reason that wetting is usually unfavorable in the carbon/metal system. Here we report a powder-metallurgy based strategy to construct a three-dimensional continuous graphene network architecture in a copper matrix through thermal-stress-induced welding between graphene-like nanosheets grown on the surface of copper powders. The interpenetrating structural feature of the as-obtained composites not only promotes the interfacial shear stress to a high level and thus results in significantly enhanced load transfer strengthening and crack-bridging toughening simultaneously, but also constructs additional three-dimensional hyperchannels for electrical and thermal conductivity. Our approach offers a general way for manufacturing metal matrix composites with high overall performance.

Jun 4, 2020

Metasurface opens world of polarization

Posted by in categories: biotech/medical, materials

Polarization, the direction in which light vibrates, is invisible to the human eye. Yet, so much of our optical world relies on the control and manipulation of this hidden quality of light.

Materials that can manipulate the polarization of —known as birefringent materials—are used in everything from digital alarm clocks to medical diagnostics, communications and astronomy.

Just as light’s polarization can vibrate along a straight line or an ellipse, materials can also be linearly or elliptically birefringent. Today, most birefringent materials are intrinsically linear, meaning they can only manipulate the polarization of light in a limited way. If you want to achieve broad polarization manipulation, you need to stack multiple birefringent materials on top of one another, making these devices bulky and inefficient.

Jun 4, 2020

The truth about graphene

Posted by in category: materials

The truth about graphene. Ever since it was first discovered in 2004, graphene has been hailed as one of the most important breakthroughs in materials since the plastics revolution more than a century ago. The early predictions were that graphene would almost immediately enable the kinds of products and technologies that we’re used to seeing in sci-fi movies. Cut to more than a decade and a half later and that still hasn’t happened. Not even close. With opinions split between people overhyping graphene or calling it a massive disappointment, it’s time we got to the truth of what is really happening with this so-called ‘wonder material’.

▻ Watch the truth about solid state batteries — how close are they?: https://youtu.be/x8FEyaZxqAU

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Jun 2, 2020

Coatings for shoe bottoms could improve traction on slick surfaces

Posted by in category: materials

Inspired by the Japanese art of paper cutting, MIT engineers have designed a friction-boosting material that could be used to coat the bottom of your shoes, giving them a stronger grip on ice and other slippery surfaces.

The researchers drew on kirigami, a variation of origami that involves cutting paper as well as folding it, to create the new coating. Laboratory tests showed that when people wearing kirigami-coated shoes walked on an icy surface, they generated more friction than the uncoated shoes.

Incorporating this coating into shoes could help prevent dangerous falls on ice and other hazardous surfaces, especially among the elderly, the researchers say.

Jun 1, 2020

‘Black nitrogen’: Researchers discover new high-pressure material and solve a puzzle of the periodic table

Posted by in categories: chemistry, materials

In the periodic table of elements there is one golden rule for carbon, oxygen and other light elements: Under high pressures, they have similar structures to heavier elements in the same group of elements. But nitrogen always seemed unwilling to toe the line. However, high-pressure chemistry researchers of the University of Bayreuth have disproved this special status. Out of nitrogen, they created a crystalline structure which, under normal conditions, occurs in black phosphorus and arsenic. The structure contains two-dimensional atomic layers, and is therefore of great interest for high-tech electronics. The scientists have presented this “black nitrogen” in Physical Review Letters.

Nitrogen—an exception in the periodic system?

When you arrange the chemical elements in ascending order according to their number of protons and look at their properties, it soon becomes obvious that certain properties recur at large intervals (periods). The brings these repetitions into focus. Elements with similar properties are placed one below the other in the same column, and thus form a group of elements. At the top of a column is the element that has the fewest protons and the lowest weight compared to the other group members. Nitrogen heads element group 15, but was previously considered the “black sheep” of the group. The reason: In earlier experiments, showed no structures similar to those exhibited under normal conditions by the of this group—specifically, phosphorus, arsenic and antimony. Instead, such similarities are observed at high pressures in the neighboring groups headed by carbon and oxygen.

May 31, 2020

Squeezed graphene becomes a superconductor

Posted by in category: materials

Pressure puts a new twist on magic-angle bilayers.

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