Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: materials – Page 199

Lawrence Livermore National Laboratory (LLNL) researchers have explored high-pressure behavior of shock-compressed tantalum at the Omega Laser Facility at the University of Rochester’s Laboratory for Laser Energetics (LLE). The work showed tantalum did not follow the predicted phase changes at high pressure and instead maintained the body-centered cubic (BCC) phase until melt.

The results of the work are featured in a Physical Review Letters paper and focuses on how researchers studied the melting behavior of at multi-megabar pressures on the nanosecond timescale.

“This work provides an improved physical intuition for how materials melt and respond at such extreme conditions,” said Rick Kraus, lead author of the paper. “These techniques and improved knowledge base are now being applied to understanding how the iron cores of rocky planets solidify and also to more programmatically relevant materials as well.”

Read more | >

An exotic form of magnetism has been discovered and linked to an equally exotic type of electrons, according to scientists who analyzed a new crystal in which they appear at the National Institute of Standards and Technology (NIST). The magnetism is created and protected by the crystal’s unique electronic structure, offering a mechanism that might be exploited for fast, robust information storage devices.

The newly invented material has an unusual structure that conducts electricity but makes the flowing electrons behave as massless particles, whose is linked to the direction of their motion. In other materials, such Weyl electrons have elicited new behaviors related to electrical conductivity. In this case, however, the electrons promote the spontaneous formation of a magnetic spiral.

“Our research shows a rare example of these particles driving collective magnetism,” said Collin Broholm, a physicist at Johns Hopkins University who led the at the NIST Center for Neutron Research (NCNR). “Our experiment illustrates a unique form of magnetism that can arise from Weyl electrons.”

Read more | >

The Solar System is positively lousy with magnetic fields. They drape around (most of) the planets and their moons, which interact with the system-wide magnetic field swirling out from the Sun.

Although invisible to the naked eye, these magnetic fields leave their marks behind. Earth’s crust is riddled with magnetic materials, for example, that retain a paleomagnetic record of the planet’s changing magnetic field. And meteorites, when we are lucky enough to find them, can tell us about the magnetic field in the environment they formed in, billions of years ago.

Most of the meteorites we study in this manner are from the asteroid belt, which sits between Mars and Jupiter. But astronomers from Japan have just developed a new means of probing the magnetic materials within meteorites from much, much farther away — and thus provided a new tool for understanding the outer reaches of the early Solar System.

Read more | >

Scientists at Australia’s RMIT investigating the massive untapped potential of wave energy have come up with a novel design for a convertor they say operates with far greater efficiency than comparable solutions, and which they hope could open the door to widespread commercial use of the technology. The team’s prototype employs a novel dual-turbine design that sidesteps some common technical issues, and proved capable of harvesting twice the energy from waves as current designs in early experiments.

The idea of capturing energy from ocean waves has been around for centuries, and recently we’re starting to see modern machines designed for these purposes take to the seas in some interesting forms. This includes rotating systems that extract power from vertical and horizontal movement, blowhole-like generators that capture energy as waves push water and air through concrete chambers, and squid-like generators with buoyant arms that rise and fall with the motion of the waves.

One of the more common approaches to harnessing wave energy is known as a point absorber buoy, which consists of a flotation device on the surface that is tethered to the seabed. As the buoy moves up and down with the passing waves, it drives an energy converter mechanism built onto the tether partway below the surface. This might be a geared drivetrain that uses the linear motion to spin a flywheel and generate power, as seen in some experimental designs.

Read more | >

Researchers in Singapore and at CalTech have developed a 3D printed fabric with an interesting property: it is generally flexible but can stiffen on demand. You can see a video about the new fabric, below.

The material consists of nylon octahedrons interlocked. The cloth is enclosed in a plastic envelope and vacuum-packed. Once in a vacuum, the sheet becomes much stiffer and can hold many times its own weight.

Presumably, the idea would be to allow the material to flex in the plastic envelope until there was a need for the increased rigidity, and then remove the air. Of course, there are a lot of practical problems with that. If the envelope is no longer air tight, for example, the operation will fail. It is also hard to rapidly remove the air from the bag to make, say, something like Batman’s cape which was a comparison the researchers drew.

Read more | >

A team of researchers in northern China developed the world’s hardest glassy material, the transparent, yellow-tinted AM-III, which is capable of leaving a deep scratch on the surface of a diamond, a report from South China Morning Post explains.

The material, which is made entirely of carbon, reached a 113 gigapascals (GPa) on the Vickers hardness test. As a point of reference, natural diamonds usually score somewhere between 50 and 70 on the GPa scale.

The findings of the research, led by Professor Tian Yongjun of Yanshan University in Qinhuangdao, Hebei province, were published in the journal National Science Review. In 2,013 Tian and his team created the world’s hardest material that’s visible to the naked eye, a boron nitride crystal that is twice as hard as diamond at 200 GPa.

Scientists developed a material called AM-III which is tougher than diamond and is almost as efficient a semiconductor as silicon.

Read more | >

A freely moving diamond trapped inside another diamond was discovered in Siberia by Alrosa in 2019. The unusual diamond, nicknamed the “Matryoshka” after the traditional Russian nesting dolls, attracted widespread interest in how this feature formed The 0.62 ct flat octahedral diamond, a twinned macle, was recently examined by the New York laboratory. Flat-bottom trigon etch pits were well developed on the face {111} (figure 1). The crystal showed a clear green bodycolor, with small dark green radiation stains in shallow fractures along the edges when viewed from the top of the crystal. Two etch channels on opposite sides of the edges had rectangular openings about 0.2 mm in width. The channels extended into the internal enclosed cavity. These features made this diamond unique. Trapped in the cavity was a small, flat diamond crystal with a hexagonal outline. The small diamond, covered with some green radiation stains on the surface, is entirely detached from its host crystal and can move freely inside. The surface of the small diamond was covered with groups of straight parallel striations following the diamond crystal symmetry. No etched trigons were observed on the surfaces of the small diamond (figure 2). Except for tiny foreign-material contaminations at the two entrances of the open channels, no other inclusions were observed in this crystal (figure 3).

Read more | >

A new way to probe exotic matter aids the study of atomic and particle physics.

Physicists have created a new way to observe details about the structure and composition of materials that improves upon previous methods. Conventional spectroscopy changes the frequency of light shining on a sample over time to reveal details about them. The new technique, Rabi-oscillation spectroscopy, does not need to explore a wide frequency range so can operate much more quickly. This method could be used to interrogate our best theories of matter in order to form a better understanding of the material universe.

Though we cannot see them with the naked eye, we are all familiar with the atoms that make up everything we see around us. Collections of positive protons, neutral neutrons and negative electrons give rise to all the matter we interact with. However, there are some more exotic forms of matter, including exotic atoms, which are not made from these three basic components. Muonium, for example, is like hydrogen, which typically has one electron in orbit around one proton, but has a positively charged muon particle in place of the proton.

Read more | >