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Category: materials – Page 63

Record-high Curie temperature achieved in ferromagnetic semiconductor

Ferromagnetic semiconductors (FMSs) combine the unique properties of semiconductors and magnetism, making them ideal candidates for developing spintronic devices that integrate both semiconductor and magnetic functionalities. However, one of the key challenges in FMSs has been achieving high Curie temperatures (TC) that enable their stable operation at room temperature.

Though previous studies achieved a TC of 420 K, which is higher than room temperature, it was insufficient for effectively operating the spin , highlighting the demand for an increase in TC among FMSs. This challenge has been featured among the 125 unsolved questions selected by the journal Science in 2005.

Materials such as (Ga, Mn)As exhibit low TC, limiting their practical use in spintronic devices. While adding Fe to narrow bandgap semiconductors like GaSb seemed promising, incorporating high concentrations of Fe while maintaining crystallinity proved difficult, restricting the attainable TC.

Eco-friendly advance brings CO₂ ‘breathing’ batteries closer to reality

Scientists at the University of Surrey have made a breakthrough in eco-friendly batteries that not only store more energy but could also help tackle greenhouse gas emissions. Lithium–CO2 “breathing” batteries release power while capturing carbon dioxide, offering a greener alternative that may one day outperform today’s lithium-ion batteries.

Until now, lithium-CO2 batteries have faced setbacks in efficiency—wearing out quickly, failing to recharge and relying on expensive rare materials such as platinum.

However, researchers from Surrey have found a way to overcome these issues by using a low-cost catalyst called cesium phosphomolybdate (CPM). Using computer modeling and , tests showed this simple change allowed the battery to store significantly more energy, charge with far less power and run for over 100 cycles.

New metamaterial enables remote movement of objects underwater using sound

Sound can do more than just provide a nice beat. Sound waves have been used for everything from mapping the seafloor to breaking apart kidney stones. Thanks to a unique material structure, researchers can now move and position objects underwater without ever touching them directly.

Dajun Zhang, a doctoral student at the University of Wisconsin-Madison, presents his work on developing a metamaterial for underwater acoustic manipulation on Tuesday, May 20, at 3:20 p.m. CT as part of the joint 188th Meeting of the Acoustical Society of America and 25th International Congress on Acoustics, running May 18–23.

A metamaterial is a that exhibits unique properties due to its structure. Zhang’s metamaterial features a small sawtooth pattern on its surface, which allows adjacent speakers to exert different forces on the material based on how the sound waves reflect off it. By carefully targeting the floating or submerged metamaterial with precise , Zhang can push and rotate any object attached to it exactly as much as he wants.

Scientists discover one of the world’s thinnest semiconductor junctions forming inside a quantum material

Scientists studying a promising quantum material have stumbled upon a surprise: within its crystal structure, the material naturally forms one of the world’s thinnest semiconductor junctions—a building block of most modern electronics. The junction is just 3.3 nanometers thick, about 25,000 times thinner than a sheet of paper.

“This was a big surprise,” said Asst. Prof. Shuolong Yang. “We weren’t trying to make this junction, but the material made one on its own, and it’s one of the thinnest we’ve ever seen.”

The discovery offers a way to build ultra-miniaturized electronic components, and also provides insight into how electrons behave in materials designed for quantum applications.

Small-scale laser systems enable high energy proton accelerator on a table-top

Laser ion acceleration uses intense laser flashes to heat electrons of a solid to enormous temperatures and propel these charged particles to extreme speeds. These have recently gained traction for applications in selectively destroying cancerous tumor cells, in processing semiconductor materials, and due to their excellent properties for imaging and fusion-relevant conditions.

Massive laser systems with several joules of light energy are needed to irradiate solids for the purpose. This produces a flash of ions which are accelerated to extreme speeds. Thus, emulating large million-volt accelerators is possible within the thickness of a hair strand.

Such lasers are typically limited to a few flashes per second to prevent overheating and damage to laser components. Thus, laser-driven ion accelerators are limited to demonstrative applications in large experimental facilities. This is far from real-world applications, where the flashes of high-velocity ions are ideally available much more frequently.

Scientists wash away mystery behind why foams are leakier than expected

Researchers from Tokyo Metropolitan University have solved a long-standing mystery behind the drainage of liquid from foams. Standard physics models wildly overestimate the height of foams required for liquid to drain out the bottom. Through careful observation, the team found that the limits are set by the pressure required to rearrange bubbles, not simply push liquid through a static set of obstacles.

Their approach highlights the importance of dynamics to understanding soft materials. The study is published in the Journal of Colloid and Interface Science.

When you spray foam on a wall, you will often see droplets of liquid trailing out the bottom. That is because foams are a dense collection of bubbles connected by walls of liquid, forming a complex labyrinth of interconnected paths. It is possible for liquid to travel along these paths, either leaving the foam or sucking in liquid which is brought into contact with the foam.

Mysteriously Perfect Sphere Spotted in Space by Astronomers

Our Milky Way galaxy is home to some extremely weird things, but a new discovery has astronomers truly baffled.

In data collected by a powerful radio telescope, astronomers have found what appears to be a perfectly spherical bubble. We know more or less what it is – it’s the ball of expanding material ejected by an exploding star, a supernova remnant – but how it came to be is more of a puzzle.

A large international team led by astrophysicist Miroslav Filipović of Western Sydney University in Australia has named the object Teleios, after the ancient Greek for “perfection”. After an exhaustive review of the possibilities, the researchers conclude that we’re going to need more information to understand how this object formed.

A new strategy to fabricate highly performing thin-film tin perovskite transistors

Tin-halide perovskites, a class of tin-based materials with a characteristic crystal structure that resembles that of the compound calcium titanate, could be promising alternatives to commonly used semiconductors. Past studies have explored the possibility of using these materials to fabricate p-channel thin-film transistors (TFTs), devices used to control and amplify the flow of charge carriers in electronics devices.

So far, however, the reliable fabrication and integration of thin-film perovskites into commercially available electronics has proved challenging. This is in part due to difficulties encountered when trying to produce uniform perovskite films with consistent electronic properties using scalable and industry-compatible methods.

Researchers at Pohang University of Science and Technology recently introduced a new promising strategy for the fabrication of highly performing TFTs based on tin-halide perovskites. Their approach, outlined in a paper published in Nature Electronics, relies on thermal evaporation and the use of lead chloride (PbCl2) as a reaction initiator.

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