nanomaterials (12)

Black Silicon...

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Fluorine gas etches the surface of silicon into a series of angular peaks that, when viewed with a powerful microscope, look much like the pyramid pattern in the sound-proofing foam shown above. Researchers at PPPL have now modeled how these peaks form in silicon, creating a material that is highly light absorbent. Credit: Pixabay/CC0 Public Domain

Topics: Energy, Environment, Materials Science, Nanomaterials, Solar Power

Researchers at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) have developed a new theoretical model explaining one way to make black silicon, an important material used in solar cells, light sensors, antibacterial surfaces, and many other applications.

Black silicon is made when the surface of regular silicon is etched to produce tiny nanoscale pits on the surface. These pits change the color of the silicon from gray to black and, critically, trap more light, an essential feature of efficient solar cells.

While there are many ways to make black silicon, including some that use the charged, fourth state of matter known as plasma, the new model focuses on a process that uses only fluorine gas. PPPL Postdoctoral Research Associate Yuri Barsukov said the choice to focus on fluorine was intentional: The team at PPPL wanted to fill a gap in publicly available research. While some papers have been published about the role of charged particles called ions in the production of black silicon, not much has been published about the role of neutral substances, such as fluorine gas.

"We now know—with great specificity—the mechanisms that cause these pits to form when fluorine gas is used," said Barsukov, one of the authors of a new paper about the work, appearing in the Journal of Vacuum Science & Technology A.

"This kind of information, published publicly and openly available, benefits us all, whether we pursue further knowledge into the basic knowledge that underlines such processes or we seek to improve manufacturing processes," Barsukov added.

How black silicon, a prized material used in solar cells, gets its dark, rough edge, Rachel Kremen, Princeton Plasma Physics Laboratory

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10x > Kevlar...

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Scientists have developed amorphous silicon carbide, a strong and scalable material with potential uses in microchip sensors, solar cells, and space exploration. This breakthrough promises significant advancements in material science and microchip technology. An artist’s impression of amorphous silicon carbide nanostrings testing to its limit tensile strength. Credit: Science Brush

Topics: Applied Physics, Chemistry, Materials Science, Nanomaterials, Semiconductor Technology

A new material that doesn’t just rival the strength of diamonds and graphene but boasts a yield strength ten times greater than Kevlar, renowned for its use in bulletproof vests.

Researchers at Delft University of Technology, led by assistant professor Richard Norte, have unveiled a remarkable new material with the potential to impact the world of material science: amorphous silicon carbide (a-SiC).

Beyond its exceptional strength, this material demonstrates mechanical properties crucial for vibration isolation on a microchip. Amorphous silicon carbide is particularly suitable for making ultra-sensitive microchip sensors.

The range of potential applications is vast, from ultra-sensitive microchip sensors and advanced solar cells to pioneering space exploration and DNA sequencing technologies. The advantages of this material’s strength, combined with its scalability, make it exceptionally promising.

Researchers at Delft University of Technology, led by assistant professor Richard Norte, have unveiled a remarkable new material with the potential to impact the world of material science: amorphous silicon carbide (a-SiC).

The researchers adopted an innovative method to test this material’s tensile strength. Instead of traditional methods that might introduce inaccuracies from how the material is anchored, they turned to microchip technology. By growing the films of amorphous silicon carbide on a silicon substrate and suspending them, they leveraged the geometry of the nanostrings to induce high tensile forces. By fabricating many such structures with increasing tensile forces, they meticulously observed the point of breakage. This microchip-based approach ensures unprecedented precision and paves the way for future material testing.

Why the focus on nanostrings? “Nanostrings are fundamental building blocks, the foundation that can be used to construct more intricate suspended structures. Demonstrating high yield strength in a nanostring translates to showcasing strength in its most elemental form.”

10x Stronger Than Kevlar: Amorphous Silicon Carbide Could Revolutionize Material Science, Delft University Of Technology

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The "Tiny Ten"...

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Researchers are working to overcome challenges related to nanoscale optoelectronic interconnects, which use light to transmit signals around an integrated circuit. IMAGE: PROVIDED BY NCNST

Topics: Biology, Materials Science, Nanoengineering, Nanomaterials, Nanotechnology, Quantum Mechanics

The promise of nanotechnology, the engineering of machines and systems at the nanoscale, is anything but tiny. Over the past decade alone, there has been an explosion in research on how to design and build components that solve problems across almost every sector, and nanotechnology innovations have led to huge advancements in our quest to address humanity’s grand challenges, from healthcare to water to food security.

Like any area of scholarship, there are still so many unknowns. And yet, there are more talented scientists and engineers endeavoring to better comprehend and harness the power of nanotechnology than ever before. The future is bright for nanotechnology and its applications.

In celebration of its 20th anniversary, the National Center for Nanoscience and Technology, China (NCNST), a subsidiary of the prestigious Chinese Academy of Sciences, partnered with Science Custom Publishing to survey nanoscience experts from the journal and across the globe about the most knotty and fascinating questions that still need to be answered if we are to advance nanotechnology in society.

The Tiny Ten: Experts weigh in on the top 10 challenges remaining for nanoscience & nanotechnology, Science Magazine

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All-Solid-State Batteries...

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 Comparison of cathode volume changes in all-solid-state cells under low-pressure operation. Credit: Korea Institute of Science and Technology

 

Topics: Batteries, Chemistry, Climate Change, Lithium, Materials Science, Nanomaterials

Often referred to as the "dream batteries," all-solid-state batteries are the next generation of batteries that many battery manufacturers are competing to bring to market. Unlike lithium-ion batteries, which use a liquid electrolyte, all components, including the electrolyte, anode, and cathode, are solid, reducing the risk of explosion, and are in high demand in markets ranging from automobiles to energy storage systems (ESS).

However, devices that maintain the high pressure (10s of MPa) required for stable operation of all-solid-state batteries have problems that reduce the battery performance, such as energy density and capacity, and must be solved for commercialization.

Dr. Hun-Gi Jung and his team at the Energy Storage Research Center at the Korea Institute of Science and Technology (KIST) have identified degradation factors that cause rapid capacity degradation and shortened lifespan when operating all-solid-state batteries at pressures similar to those of lithium-ion batteries. The research is published in the journal Advanced Energy Materials.

Unlike previous studies, the researchers confirmed for the first time that degradation can occur inside the cathode as well as outside, showing that all-solid-state batteries can be operated reliably even in low-pressure environments.

In all-solid-state batteries, the cathode and anode have a volume change during repeated charging and discharging, resulting in interfacial degradation, such as side reaction and contact loss between active materials and solid electrolytes, which increase the interfacial resistance and worsen cell performance.

To solve this problem, external devices are used to maintain high pressure, but this has the disadvantage of reducing energy density as the weight and volume of the battery increase. Research is being conducted on the inside of the all-solid-state cell to maintain the performance of the cell, even in low-pressure environments.

Investigation of the degradation mechanism for all-solid-state batteries takes another step toward commercialization, National Research Council of Science and Technology.

 

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Quasicrystal Legos...

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A mathematical tool called a fast Fourier transform maps the structure in a way that reveals the 12-fold symmetry of the quasicrystal. The fast Fourier transform of the electron microscope image of the quasicrystal is shown on the left, while the transform of the simulated crystal is shown on the right. Image credit: Mirkin Research Group, Northwestern University, and Glotzer Group, University of Michigan.

Topics: Biology, DNA, Nanoengineering, Nanomaterials, Nanotechnology

ANN ARBOR—Nanoengineers have created a quasicrystal—a scientifically intriguing and technologically promising material structure—from nanoparticles using DNA, the molecule that encodes life.

The team, led by researchers at Northwestern University, the University of Michigan, and the Center for Cooperative Research in Biomaterials in San Sebastian, Spain, reports the results in Nature Materials.

Unlike ordinary crystals, which are defined by a repeating structure, the patterns in quasicrystals don’t repeat. Quasicrystals built from atoms can have exceptional properties—for example, absorbing heat and light differently, exhibiting unusual electronic properties such as conducting electricity without resistance, or their surfaces being very hard or very slippery.

Engineers studying nanoscale assembly often view nanoparticles as a kind of ‘designer atom,’ which provides a new level of control over synthetic materials. One of the challenges is directing particles to assemble into desired structures with useful qualities, and in building this first DNA-assembled quasicrystal, the team entered a new frontier in nanomaterial design.

“The existence of quasicrystals has been a puzzle for decades, and their discovery appropriately was awarded a Nobel Prize,” said Chad Mirkin, the George B. Rathmann Professor of Chemistry at Northwestern University and co-corresponding author of the study. “Although there are now several known examples, discovered in nature or through serendipitous routes, our research demystifies their formation and, more importantly, shows how we can harness the programmable nature of DNA to design and assemble quasicrystals deliberately.”

Nanoparticle quasicrystal constructed with DNA, Kate McAlpine, University of Michigan

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Liquid Squeezing...

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That isn't tea, but the paradox still applies: Dispersing gold nanoparticles in an aqueous chlorine solution. (Courtesy: Ai Du)

Topics: Aerogels, Einstein, Materials Science, Nanomaterials, Soft Materials

If you stir a colloidal solution containing nanoparticles, you might expect the particles to disperse evenly through the liquid. But that’s not what happens. Instead, the particles end up concentrated in a specific region and may even clump together. This unexpected result is an example of Einstein’s tea leaf paradox, and the researchers at Tongji University in China who discovered it – quite by accident – say it could be used to collect particles or molecules for detection in a dilute solution. Importantly, it could also be used to make aerogels for technological applications.

We usually stir a liquid to evenly disperse the substances in it. The phenomenon known as Einstein’s tea leaf paradox describes a reverse effect in which the leaves in a well-stirred cup of tea instead become concentrated in a doughnut-shaped area and gather at the bottom center of the cup once stirring ceases. While this paradox has been known about for more than 100 years and is understood to be caused by a secondary flow effect, there are few studies on how it manifests for nanoparticles in a stirred solution.

Liquid "squeezing"

Researchers led by Ai Du of the School of Physics, Science, and Engineering at Tongji University in Shanghai have now simulated how gold nanoparticle spheres dispersed in water move when the solution is stirred. When they calculated the flow velocity distribution of the fluid, they found that the rate at which the particles moved appeared to follow the fluid’s flow velocity.

“Interestingly, by dividing the whole container into several sectors, we also observed that the high-velocity region driven by the stirrer was also the region in which the particles aggregated,” explains Du. “We think that this phenomenon is probably due to direct ‘squeezing’ of the liquid created by the stirrer and comes from the mass differences between the nanoparticles and the liquid phase.”

Einstein’s tea leaf paradox could help make aerogels, Isabelle Dumé, Physics World.

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Chemistry...

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Topics: Chemistry, Nanomaterials, Nanotechnology, Nobel Laureate, Nobel Prize

Prize announcement. NobelPrize.org. Nobel Prize Outreach AB 2023. Wed. 4 Oct 2023. < https://www.nobelprize.org/prizes/chemistry/2023/prize-announcement/ >

4 October 2023

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Chemistry 2023 to

Moungi G. Bawendi
Massachusetts Institute of Technology (MIT), Cambridge, MA, USA

Louis E. Brus
Columbia University, New York, NY, USA

Alexei I. Ekimov
Nanocrystals Technology Inc., New York, NY, USA

“for the discovery and synthesis of quantum dots”

They planted an important seed for nanotechnology

The Nobel Prize in Chemistry 2023 rewards the discovery and development of quantum dots, nanoparticles so tiny that their size determines their properties. These smallest components of nanotechnology now spread their light from televisions and LED lamps and can also guide surgeons when they remove tumor tissue, among many other things.

Everyone who studies chemistry learns that an element’s properties are governed by how many electrons it has. However, when matter shrinks to nano-dimensions, quantum phenomena arise; these are governed by the size of the matter. The Nobel Laureates in Chemistry 2023 have succeeded in producing particles so small that their properties are determined by quantum phenomena. The particles, which are called quantum dots, are now of great importance in nanotechnology.

“Quantum dots have many fascinating and unusual properties. Importantly, they have different colors depending on their size,” says Johan Åqvist, Chair of the Nobel Committee for Chemistry.

Physicists had long known that, in theory, size-dependent quantum effects could arise in nanoparticles, but at that time, it was almost impossible to sculpt in nanodimensions. Therefore, few people believed that this knowledge would be put to practical use.

However, in the early 1980s, Alexei Ekimov succeeded in creating size-dependent quantum effects in colored glass. The color came from nanoparticles of copper chloride, and Ekimov demonstrated that the particle size affected the color of the glass via quantum effects.

A few years later, Louis Brus was the first scientist in the world to prove size-dependent quantum effects in particles floating freely in a fluid.

In 1993, Moungi Bawendi revolutionized the chemical production of quantum dots, resulting in almost perfect particles. This high quality was necessary for them to be utilized in applications.

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Stronger Than Steel...

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Researchers from the University of Connecticut and colleagues have created a highly durable, lightweight material by structuring DNA and then coating it in glass. The resulting product, characterized by its nanolattice structure, exhibits a unique combination of strength and low density, making it potentially useful in applications like vehicle manufacturing and body armor. (Artist’s concept.)

Topics: Biotechnology, DNA, Material Science, Nanomaterials

Researchers have developed a highly robust material with an extremely low density by constructing a structure using DNA and subsequently coating it in glass.

Materials possessing both strength and lightness have the potential to enhance everything from automobiles to body armor. But usually, the two qualities are mutually exclusive. However, researchers at the University of Connecticut, along with their collaborators, have now crafted an incredibly strong yet lightweight material. Surprisingly, they achieved this using two unexpected building blocks: DNA and glass.

“For the given density, our material is the strongest known,” says Seok-Woo Lee, a materials scientist at UConn. Lee and colleagues from UConn, Columbia University, and Brookhaven National Lab reported the details on July 19 in Cell Reports Physical Science.

Strength is relative. Iron, for example, can take 7 tons of pressure per square centimeter. But it’s also very dense and heavy, weighing 7.8 grams/cubic centimeter. Other metals, such as titanium, are stronger and lighter than iron. And certain alloys combining multiple elements are even stronger. Strong, lightweight materials have allowed for lightweight body armor and better medical devices and made safer, faster cars and airplanes.

Scientists Create New Material Five Times Lighter and Four Times Stronger Than Steel. Sci-Tech Daily

Reference: “High-strength, lightweight nano-architected silica” by Aaron Michelson, Tyler J. Flanagan, Seok-Woo Lee, and Oleg Gang, 27 June 2023, Cell Reports Physical Science.
DOI: 10.1016/j.xcrp.2023.101475

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Build Better Batteries...

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Electric field- and pressure-assisted fast sintering to control graphene alignment in thick composite electrodes for boosting lithium storage performance. Credit: Hongtao Sun, Penn State

Topics: Battery, Energy, Graphene, Green Tech, Lithium, Materials Science, Nanomaterials

The demand for high-performance batteries, especially for use in electric vehicles, is surging as the world shifts its energy consumption to a more electric-powered system, reducing reliance on fossil fuels and prioritizing climate remediation efforts. To improve battery performance and production, Penn State researchers and collaborators have developed a new fabrication approach that could make for more efficient batteries that maintain energy and power levels.

The improved method for fabricating battery electrodes may lead to high-performance batteries that would enable more energy-efficient electric vehicles, as well as such benefits as enhancing power grid storage, according to Hongtao Sun. Sun is an assistant professor of industrial and manufacturing engineering at Penn State and the co-corresponding author of the study, which was published in and featured on the front cover of Carbon.

"With current batteries, we want them to enable us to drive a car for longer distances, and we want to charge the car in maybe five minutes, 10 minutes, comparable to the time it takes to fill up for gas," Sun said. "In our work, we considered how we can achieve this by making the electrodes and battery cells more compact, with a higher percentage of active components and a lower percentage of passive components."

If an electric car maker wants to improve the driving distance of their vehicles, they add more battery cells, numbering in the thousands. The smaller and lighter, the better, according to Sun.

"The solution for longer driving distances for an electric vehicle is just to add compact batteries, but with denser and thicker electrodes," Sun said, explaining that such electrodes could better connect and power the battery's components, making them more active. "Although this approach may slightly reduce battery performance per electrode weight, it significantly enhances the vehicle's overall performance by reducing the battery package's weight and the energy required to move the electric vehicle."

Thicker, denser, better: New electrodes may hold the key to advanced batteries, Jamie Oberdick, Pennsylvania State University, techxplore.

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Beyond Attogram Imaging...

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When X-rays (blue color) illuminate an iron atom (red ball at the center of the molecule), core-level electrons are excited. X-ray excited electrons are then tunneled to the detector tip (gray) via overlapping atomic/molecular orbitals, which provide elemental and chemical information about the iron atom. Credit: Saw-Wai Hla

Topics: Applied Physics, Instrumentation, Materials Science, Nanomaterials, Quantum Mechanics

A team of scientists from Ohio University, Argonne National Laboratory, the University of Illinois-Chicago, and others, led by Ohio University Professor of Physics, and Argonne National Laboratory scientist, Saw Wai Hla, have taken the world's first X-ray SIGNAL (or SIGNATURE) of just one atom. This groundbreaking achievement could revolutionize the way scientists detect materials.

Since its discovery by Roentgen in 1895, X-rays have been used everywhere, from medical examinations to security screenings in airports. Even Curiosity, NASA's Mars rover, is equipped with an X-ray device to examine the material composition of the rocks on Mars. An important usage of X-rays in science is to identify the type of materials in a sample. Over the years, the quantity of materials in a sample required for X-ray detection has been greatly reduced thanks to the development of synchrotron X-rays sources and new instruments. To date, the smallest amount one can X-ray a sample is in an attogram, which is about 10,000 atoms or more. This is due to the X-ray signal produced by an atom being extremely weak, so conventional X-ray detectors cannot be used to detect it. According to Hla, it is a long-standing dream of scientists to X-ray just one atom, which is now being realized by the research team led by him.

"Atoms can be routinely imaged with scanning probe microscopes, but without X-rays, one cannot tell what they are made of. We can now detect exactly the type of a particular atom, one atom-at-a-time, and can simultaneously measure its chemical state," explained Hla, who is also the director of the Nanoscale and Quantum Phenomena Institute at Ohio University. "Once we are able to do that, we can trace the materials down to the ultimate limit of just one atom. This will have a great impact on environmental and medical sciences and maybe even find a cure that can have a huge impact on humankind. This discovery will transform the world."

Their paper, published in the scientific journal Nature on May 31, 2023, and gracing the cover of the print version of the scientific journal on June 1, 2023, details how Hla and several other physicists and chemists, including Ph.D. students at OHIO, used a purpose-built synchrotron X-ray instrument at the XTIP beamline of Advanced Photon Source and the Center for Nanoscale Materials at Argonne National Laboratory.

Scientists report the world's first X-ray of a single atom, Ohio University, Phys.org.

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Mice, Men, and Nanoparticles...

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Graphical abstract. Credit: Nanomaterials (2023). DOI: 10.3390/nano13081404

Topics: Biology, Environment, Nanomaterials, Nanotechnology

Among the biggest environmental problems of our time, micro- and nanoplastic particles (MNPs) can enter the body in various ways, including through food. And now, for the first time, research conducted at MedUni Vienna has shown how these minute particles manage to breach the blood-brain barrier and, consequently, penetrate the brain. The newly discovered mechanism provides the basis for further research to protect humans and the environment.

Published in the journal Nanomaterials, the study was carried out in an animal model with oral administration of MNPs, in this case, polystyrene, a widely-used plastic found in food packaging. Led by Lukas Kenner (Department of Pathology at MedUni Vienna and Department of Laboratory Animal Pathology at Vetmeduni) and Oldamur Hollóczki (Department of Physical Chemistry, University of Debrecen, Hungary), the research team was able to determine that tiny polystyrene particles could be detected in the brain just two hours after ingestion.

The mechanism that enabled them to breach the blood-brain barrier was previously unknown to medical science. "With the help of computer models, we discovered that a certain surface structure (biomolecular corona) was crucial in enabling plastic particles to pass into the brain," Oldamur Hollóczki explained.

Study shows how tiny plastic particles manage to breach the blood-brain barrier, Medical University of Vienna, Phys.org

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Magnetic Plasmons in Nanostructures...

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FIG. 1. (a) Sketches of the excitations of surface plasmons polaritons - SPP (top), localized surface plasmons - LSP (middle), and magnetic plasmons - MP (bottom). All these excitations are associated with a collective motion of surface charges under light illumination. (b) Diagram of MP-based plasmonic nanostructures used for fundamental studies and their applications in various research fields.

Topics: Electromagnetism, Magnetism, Metamaterials, Nanoclusters, Nanomaterials, Plasmonic Nanostructures

Abstract

The magnetic response of most natural materials, characterized by magnetic permeability, is generally weak. Particularly in the optical range, the weakness of magnetic effects is directly related to the asymmetry between electric and magnetic charges. Harnessing artificial magnetism started with a pursuit of metamaterial design exhibiting magnetic properties. A plasmonic nanostructure called split-ring resonators gave the first demonstration of artificial magnetism. Engineered circulating currents form magnetic plasmons, acting as the source of artificial magnetism in response to external electromagnetic excitation. In the past two decades, magnetic plasmons supported by plasmonic nanostructures have become an active topic of study. This Perspective reviews the latest studies on magnetic plasmons in plasmonic nanostructures. A comprehensive summary of various plasmonic nanostructures supporting magnetic plasmons, including split-ring resonators, metal–insulator–metal structures, metallic deep groove arrays, and plasmonic nanoclusters, is presented. Fundamental studies and applications based on magnetic plasmons are discussed. The formidable challenges and the prospects of the future study directions on developing magnetic plasmonic nanostructures are proposed.

Magnetic plasmons in plasmonic nanostructures: An overview

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