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Archive for the ‘materials’ category: Page 231

May 24, 2019

Lithium doesn’t crack under pressure, it transforms

Posted by in categories: materials, quantum physics

Using cutting-edge theoretical calculations performed at NERSC, researchers at Berkeley Lab’s Molecular Foundry have predicted fascinating new properties of lithium—a light alkali metal that has intrigued scientists for two decades with its remarkable diversity of physical states at high pressures.

“Under standard conditions, is a simple metal that forms a textbook crystalline solid. However, scientists have shown that when you put a lithium crystal under , the atomic structure changes and, somewhat counterintuitively, its conductivity drops, becoming less metallic,” said Stephanie Mack, a graduate student research assistant at Berkeley Lab and first author of the study, published in PNAS. “We’ve discovered it also becomes topological, with electronic properties similar to graphene.”

Topological materials are a recently discovered class of solids that display exotic properties, such as having insulating interiors yet highly conductive surfaces, even when deformed. They are exciting for potential applications in next-generation electronics and quantum information science. According to coauthors Sinéad Griffin and Jeff Neaton, lithium becomes topological at high but experimentally achievable pressures, comparable to one-quarter of the pressure at the Earth’s center.

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May 23, 2019

For this metal, electricity flows, but not the heat

Posted by in category: materials

There’s a known rule-breaker among materials, and a new discovery by an international team of scientists adds more evidence to back up the metal’s nonconformist reputation. According to a new study led by scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and at the University of California, Berkeley, electrons in vanadium dioxide can conduct electricity without conducting heat.

The findings, to be published in the Jan. 27 issue of the journal Science, could lead to a wide range of applications, such as thermoelectric systems that convert waste from engines and appliances into electricity.

For most metals, the relationship between electrical and thermal conductivity is governed by the Wiedemann-Franz Law. Simply put, the law states that good conductors of electricity are also good conductors of heat. That is not the case for metallic , a material already noted for its unusual ability to switch from an insulator to a metal when it reaches a balmy 67 degrees Celsius, or 152 degrees Fahrenheit.

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May 23, 2019

Behold the mayo: Experiments reveal ‘instability threshold’ of elastic-plastic material

Posted by in categories: engineering, materials

Arindam Banerjee, an associate professor of mechanical engineering and mechanics at Lehigh University, studies the dynamics of materials in extreme environments. He and his team have built several devices to effectively investigate the dynamics of fluids and other materials under the influence of high acceleration and centrifugal force.

One area of interest is Rayleigh-Taylor instability, which occurs between materials of different densities when the density and pressure gradients are in opposite directions creating an unstable stratification.

“In the presence of gravity—or any accelerating field—the two materials penetrate one another like ‘fingers,’” says Banerjee.

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May 23, 2019

Robots activated by water may be the next frontier

Posted by in categories: materials, robotics/AI

New research from the laboratory of Ozgur Sahin, associate professor of biological sciences and physics at Columbia University, shows that materials can be fabricated to create soft actuators—devices that convert energy into physical motion—that are strong and flexible, and, most important, resistant to water damage.

“There’s a growing trend of making anything we interact with and touch from materials that are dynamic and responsive to the environment,” Sahin says. “We found a way to develop a material that is water-resistant yet, at the same time, equipped to harness water to deliver the force and motion needed to actuate .”

The research was published online May 21 in Advanced Materials Technologies.

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May 23, 2019

Hemp Derived Carbon Nanosheets Better Than Graphene

Posted by in category: materials

https://youtube.com/watch?v=49JB_pyPEic

Researchers have created carbon nanosheets for use as supercapacitors with waste hemp fibres, and can do this at 1/1000th of the cost of graphene!

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May 22, 2019

Scientists break record for highest-temperature superconductor

Posted by in category: materials

University of Chicago scientists are part of an international research team that has discovered superconductivity—the ability to conduct electricity perfectly—at the highest temperatures ever recorded.

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May 21, 2019

Controlling Concrete Production

Posted by in category: materials

This device helps builders create high quality concrete via Carmix Metalgalante.

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May 21, 2019

Scientists Have Created Shape Shifting Liquid Metal That Can Be Programmed

Posted by in categories: innovation, materials

In a terrifying breakthrough similar to the metal morphing villain in Terminator 2, scientists at the University of Sussex and Swansea University have discovered a way to apply electrical charges to liquid metal and coax it into 3D shapes such as letters and even a heart.

This discovery has been called an “extremely promising” new kind of material that can be programmed to alter its shape.

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May 20, 2019

Deflecting Earthquakes The Way Ancient Romans Did It

Posted by in category: materials

A recent French study indicates that the ancient Romans may have figured out how to deal with earthquakes by simply deflecting the energy of the waves using structures that resemble metamaterials. These are materials which can manipulate waves (electromagnetic or otherwise) in ways which are normally deemed impossible, such as guiding light around an object using a special pattern.

In a 2012 study, the same researchers found that a pattern of 5 meter deep bore holes in the ground was effective at deflecting a significant part of artificially generated acoustic waves. One of the researchers, [Stéphane Brûlé], noticed on an aerial photograph of a Gallo-Roman theater near the town of Autun in central France that its pattern of pillars bore an uncanny resemblance to this earlier experiment: a series of concentric (semi) circles with the distance between the pillars (or holes) decreasing nearer the center.

Further research using archaeological data of this theater site confirmed that it did appear to match up the expected pattern if one would have aimed to design a structure that could successfully deflect the acoustic energy from an earthquake. This raises the interesting question of whether this was a deliberate design choice, or just coincidence.

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May 20, 2019

Geologists Just Discovered a Source of Volcanoes Deeper Than Ever Before

Posted by in categories: materials, space

Researchers have pinpointed a previously unknown source of volcanoes in the extreme depths of Earth — in the transition zone between the upper and lower mantle.

Until now, we thought we had a handle on the ways in which volcanoes form, welling up from the molten regions in the upper mantle beneath our planet’s crust, but the new discovery takes things much farther down.

In the Bermuda islands, which sit atop an extinct volcanic seamount, geologists have found the first direct evidence that material from the transition zone, between 400 and 650 kilometres (250 and 400 miles) below Earth’s surface, can bubble up and be spewed out of volcanoes.

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