materialsscienceandengineering

[materialsscienceandengineering]

Advancing diverse emerging solar cells with a 2D-transition metal dichalcogenide buffer

Thin-film solar cells comprising CdTe, Cu(In,Ga)Se2 have become a less-expensive photovoltaic technology than crystalline Si wafer solar cells. Still, their efficiencies are inferior to those of their predecessors in terms of commercialization. Moreover, they consist of scarce and toxic elements. Therefore, diverse semiconductors including Cu2MSnS4 (M = Co, Mn, Fe, Mg) of group I2-II-IV-VI4 are gaining attention due to their nontoxic nature, Earth abundance and remarkable photovoltaic properties. However, unsuitable band alignment with toxic cadmium sulfide (CdS) buffer restricts their experimental power conversion efficiencies (PCEs) to less than 5%. Exploring alternative buffers is the best path to improve their PCE.

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Study unveils contributions to superconductivity in the vortex lattice structure of 2H-NbSe₂

Superconductivity is a quantum property of materials entailing an electrical resistance of zero at very low temperatures. In some materials, multiple electronic bands are known to contribute to the emergence of superconductivity, leading to multiple superconducting energy gaps. This phenomenon is referred to as multiband superconductivity. Researchers at Lund University in Sweden, Institut Laue Langevin in France and other institutes in Europe recently carried out a study aimed at better understanding the multiband superconductivity emerging in the transition metal dichalcogenide 2H-NbSe2, which exhibits a vortex lattice when exposed to a magnetic field. Their findings, published in Physical Review Letters, unveil two key contributions to the superconducting state observed in this material.

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Wild fig tree rings offer a cheap method for tracking toxic atmospheric mercury, a byproduct of gold mining in the Global South, according to a new Cornell University study. Research was conducted in the Peruvian Amazon and published April 8 in the journal Frontiers in Environmental Science. Computer models suggest that atmospheric mercury can potentially travel across the globe, to be deposited back in landscapes. When it falls to the ground or in water, it can accumulate in organisms such as fish and other food sources, where it acts as a neurotoxin to both humans and wildlife.

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Serendipitous discovery boosts catalyst efficiency using hot car exhaust

Preparing catalysts by sending hot, steamy car exhaust over them could improve their efficiency and reduce the amount of rare and expensive metals required in vehicle catalytic converters and many other emission control and industrial processes. Reporting in the journal Nature, an international team of researchers found that the hot car exhaust containing nitrogen oxides and carbon monoxide caused a previously unknown reaction that, used proactively, can significantly improve catalytic activity. Catalysts are substances that increase the rate of chemical reactions. The researchers found that hot exhaust encouraged ceria particles, one of the components of the catalyst materials, to form two-dimensional, nano-sized clusters. These clusters, densely covering the surface, create many sites where chemical reactions can happen, increasing the efficiency of the process.

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Amorphization alters nanocatalyst properties: Research shows the impact of structural disorder

A research team studied how iridium and palladium nanoparticles can change the properties of catalysts with minor degradation and transition to an amorphous state. The team includes Skoltech and Khakassian State University researchers led by Skoltech Professor Alexander Kvashnin, a Doctor of Sciences in Physics and Mathematics. The results are published in the Journal of Catalysis. They provide insights into important catalysts for oxygen and hydrogen evolution reactions, as well as oxygen reduction reactions. The transition from microparticles to nanoparticles leads to large changes in the physical and chemical properties of the material. In nanoparticles, the number of atoms on the surface and in the particle is practically the same.

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Cell membrane biology inspires design of new saltwater filters

Researchers at the Francis Crick Institute, King's College London and the University of Fribourg have developed polymer water channels, similar to commonly used plastics, that can draw salt out of water, inspired by the body's own water filtering system. If their innovation could be scaled up and produced industrially, this could help to filter seawater to create drinking water. Aquaporins are proteins that rapidly transport water across cell membranes while excluding salt. They are critical for maintaining the right balance of water inside and outside cells and for concentrating or diluting urine in the kidneys. In research published recently in Angewandte Chemie International Edition, an international team of researchers took inspiration from aquaporins to design artificial water channels that can be used to filter salt out of water.

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Controlling quantum particle states through structural phase transition of crystals

A research team has successfully fine-tuned the Rabi oscillation of polaritons, quantum composite particles, by leveraging changes in electrical properties induced by crystal structure transformation. Published in Advanced Science, this study demonstrates that the properties of quantum particles can be controlled without the need for complex external devices, which is expected to greatly enhance the feasibility of practical quantum technology. The team was led by Professor Chang-Hee Cho from the Department of Physics and Chemistry at DGIST. Quantum technology enables much faster and more precise information processing than conventional electronic devices and is gaining attention as a key driver of future industries, including quantum computing, communications, and sensors. At the core of this technology lies the ability to accurately generate and control quantum states. In particular, recent research has been actively exploring light-based quantum devices, with polaritons at the center of this field.

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A Cornell University-led collaboration has hit the trifecta of sustainability technology: The group has developed a low-cost method to produce carbon-free "green" hydrogen via solar-powered electrolysis of seawater. A happy byproduct of the process? Potable water. The team's hybrid solar distillation-water electrolysis (HSD-WE) device, reported April 9 in Energy and Environmental Science, currently produces 200 milliliters of hydrogen per hour with 12.6% energy efficiency directly from seawater under natural sunlight. The researchers estimate that within 15 years, the technology could reduce the cost of green hydrogen production to $1 per kilogram -- a key step in achieving net-zero emissions by 2050.

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Tiny, soft robot flexes its potential as a lifesaver

A tiny, soft, flexible robot that can crawl through earthquake rubble to find trapped victims or travel inside the human body to deliver medicine may seem like science fiction, but an international team led by researchers at Penn State are pioneering such adaptable robots by integrating flexible electronics with magnetically controlled motion. Soft robotics, unlike traditional rigid robots, are made from flexible materials that mimic the movement of living organisms. This flexibility makes them ideal for navigating tight spaces, such as debris in a disaster zone or the intricate pathways of the human body. However, integrating sensors and electronics into these flexible systems has posed a significant challenge, according Huanyu "Larry" Cheng, James L. Henderson, Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State.

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Longstanding model fails to explain spin dynamics in 1D cuprates

Superconductivity—the ability of some materials to conduct electricity with no energy loss—holds immense promise for new technologies from lossless power grids to advanced quantum devices. A publication in Physical Review Letters by researchers at the Stanford Institute for Materials and Energy Sciences (SIMES) at the Department of Energy's SLAC National Accelerator Laboratory sheds light on an outstanding mystery in the study of superconductivity: high-temperature superconductivity in cuprates. Doubling down on results from a previous SLAC study, the paper provides further evidence that the Hubbard model—the leading theory for describing strong correlations between electrons in quantum materials—fails to explain electron dynamics in cuprates, even in simplified, one-dimensional systems.

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Infrared heavy-metal-free quantum dots deliver sensitive and fast sensors for eye-safe LIDAR applications

The frequency regime lying in the shortwave infrared (SWIR) has very unique properties that make it ideal for several applications, such as being less affected by atmospheric scattering as well as being "eye-safe." These include Light Detection and Ranging (LIDAR), a method for determining ranges and distances using lasers, space localization and mapping, adverse weather imaging for surveillance and automotive safety, environmental monitoring, and many others. However, SWIR light is currently confined to niche areas, like scientific instrumentation and military use, mainly because SWIR photodetectors rely on expensive and difficult-to-manufacture materials. In the past few years, colloidal quantum dots—solution-processed semiconducting nanocrystals—have emerged as an alternative for mainstream consumer electronics.

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Scientists discover method to restore vanishing electronic patterns in quantum materials

A new study published in Nature Communications April 7 could reshape the future of magnetic and electronic technology. Scientists at Rice University have discovered how a disappearing electronic pattern in a quantum material can be revived under specific thermal conditions. The finding opens new doors for customizable quantum materials and in-situ engineering, where devices are manufactured or manipulated directly at their point of use. Led by Pengcheng Dai, the Sam and Helen Worden Professor of Physics and Astronomy, the researchers uncovered the cause behind a vanishing electronic phenomenon in a class of crystalline materials known as kagome lattice, a geometric arrangement of corner-sharing triangles named after a traditional Japanese basket pattern. This discovery reveals how heating methods impact the presence of a charge density wave (CDW), a quantum pattern of electron arrangement, in the kagome metal iron germanide (FeGe). It also demonstrates how its reappearance enhances magnetic and electronic properties.

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While there is an astounding variety of physical differences in wildlife that humans can easily observe, new research from Drexel University's College of Arts and Sciences reveals that there is likely even more variation hidden from our perception. In a study recently published in The Wilson Journal of Ornithology, the researchers report their discovery of fluorescent pigments in the feathers of Long-eared Owls, that can only be seen by humans with the help of ultraviolet light. The study, led by Emily Griffith, a PhD candidate in the Biodiversity, Earth & Environmental Science department, shows that fluorescent pigments in the feathers of Long-eared Owls can vary within a population and that variation gives clues as to why the owls have these special pigments. To conduct the research, the team used a fluorometer -- a device that measures fluorescence or light that is emitted after absorbing radiation such as UV light -- to measure variation in the amount of fluorescent pigments in the feathers of Long-eared Owls migrating through the Upper Peninsula of Michigan in the spring of 2020.

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Frustration incorporated: How mismatched geometries can enhance material strength and toughness

Anyone who's ever tried tiling a floor, a backsplash or even an arts-and-crafts project probably knows the emotional frustration of working with pieces whose shapes don't perfectly complement each other. It turns out, though, that some creatures may actually rely on similar mismatches to create geometric frustrations that result in complex natural structures with remarkable properties, such as protective shells and sturdy yet flexible bones. Now, researchers at the University of Michigan have developed mathematical models showing one way that nature achieves this. These models, in turn, could help design advanced materials for medical devices, sustainable construction and more. "Frustration—using these mismatched building blocks—gives rise to wonderful complexity and that complexity can be useful in providing superior material properties," said Xiaoming Mao, U-M professor of physics and senior author of the new study.

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Q&A: Scientists uncover process behind plastic's dangerous fragment shedding

The world is littered with trillions of micro- and nanoscopic pieces of plastic. These can be smaller than a virus—just the right size to disrupt cells and even alter DNA. Researchers find them almost everywhere they've looked, from Antarctic snow to human blood. In a new study published in the journal Nature Communications, scientists have delineated the molecular process that causes these small pieces to break off in such large quantities. Since hitting the market 75 years ago, plastic has become ubiquitous—and so, presumably, have nanoplastics. As it turns out, the qualities that make plastic strong and flexible also make it prone to forming nanoplastics—this is true for 75–80% of all plastics used, which are termed as semicrystalline polymers in the community.

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Physicists uncover a metallic altermagnet with d-wave spin splitting at room temperature

For many years, physics studies focused on two main types of magnetism, namely ferromagnetism and antiferromagnetism. The first type entails the alignment of electron spins in the same direction, while the latter entails the alignment of electron spins in alternating, opposite directions. Yet recent studies have discovered a new kind of magnetism, referred to as altermagnetism, which does not fit into either of the previously identified categories. Altermagnetism is characterized by the breaking of time-reversal symmetry (i.e., the symmetry of physical laws when time is reversed) and spin-split band structures, in materials that retain a zero net magnetization.

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Making the physics of glass more transparent

For centuries, humans have made use of glass in their art, tools, and technology. Despite the ubiquity of this material, however, many of its microscopic properties are not well understood, and it continues to defy conventional physical description. Enter Koun Shirai of the University of Osaka. In an article published in Foundations, Shirai bridges conventional physical theory and the study of nonequilibrium materials to provide a robust description for the thermodynamics of glasses. Most materials exist in an equilibrium state, meaning that the forces and torques on the material's atoms are all balanced. Glasses, however, are a famous exception: they are amorphous solid materials whose atoms are always rearranging, albeit very slowly, toward an equilibrium state but do not exist in equilibrium.

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