Nanotechnology News and Discussions

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Physicists invent intelligent quantum sensor of light waves
https://phys.org/news/2022-09-physicist ... ensor.html
by Amanda Siegfried, University of Texas at Dallas

University of Texas at Dallas physicists and their collaborators at Yale University have demonstrated an atomically thin, intelligent quantum sensor that can simultaneously detect all the fundamental properties of an incoming light wave.

The research, published April 13 in the journal Nature, demonstrates a new concept based on quantum geometry that could find use in health care, deep-space exploration and remote-sensing applications.

"We are excited about this work because typically, when you want to characterize a wave of light, you have to use different instruments to gather information, such as the intensity, wavelength and polarization state of the light. Those instruments are bulky and can occupy a significant area on an optical table," said Dr. Fan Zhang, a corresponding author of the study and associate professor of physics in the School of Natural Sciences and Mathematics.

[Nanotechandmorefuture]

Optical Nanomotor Drives Future Innovations in Tiny Power Sources
Interview conducted by Megan Craig, M.Sc.
Sep 6 2022

https://www.azonano.com/article.aspx?ArticleID=6254

In this interview, AZoNano discusses the development of a novel solid-state optical nanomotor, which is driven by light. This nanomotor is the first of its kind, and could have significant applications for the design of power sources in a range of existing and future technologies.

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A new experimental study tackles the unsolved mystery of 'nanobubbles'
https://phys.org/news/2022-09-experimen ... bbles.html
by Ingrid Fadelli , Phys.org

Nanobubbles are extremely small (i.e., nanoscopic) gaseous cavities that some physicists observed in aqueous solutions, typically after specific substances were dissolved in them. While some studies reported the observation of these incredibly tiny bubbles, some scientists have argued that they are merely solid or oily residues formed during experiments.

Researchers at Centro de Investigación y de Estudios Avanzados Unidad Monterrey and Centro de Investigación en Matemáticas Unidad Monterrey in Mexico have recently carried out an experiment aimed at further investigating the nature of these elusive and mysterious objects, specifically when xenon and krypton were dissolved in water. Their study, featured in Physical Review Letters, identified the formation of what the team refers to as "nanoblobs," yet found no evidence of nanobubbles.

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Physicists generate new nanoscale spin waves
https://phys.org/news/2022-09-physicists-nanoscale.html
by Tom Leonhardt, Martin-Luther-Universität Halle-Wittenberg

Strong alternating magnetic fields can be used to generate a new type of spin wave that was previously just theoretically predicted. This was achieved for the first time by a team of physicists from Martin Luther University Halle-Wittenberg (MLU). They report on their work in Nature Communications and provide the first microscopic images of these spin waves.

The basic idea of spintronics is to use a special property of electrons—spin—for various electronic applications such as data and information technology. The spin is the intrinsic angular momentum of electrons that produces a magnetic moment. Coupling these magnetic moments creates the magnetism that could ultimately be used in information processing. When these coupled magnetic moments are locally excited by a magnetic field pulse, this dynamic can spread like waves throughout the material. These are referred to as spin waves or magnons.

[Yuli Ban]

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Drawing data at the nanometer scale
https://phys.org/news/2022-09-nanometer-scale.html
by Pohang University of Science & Technology (POSTECH)

A method to draw data in an area smaller than 10 nanometers has been proposed in a recent study published in Physical Review Letters

A joint research team led by Professor Daesu Lee (Department of Physics) of POSTECH, Professor Se Young Park (Department of Physics) at Soongsil University, and Dr. Ji Hye Lee (Department of Physics and Astronomy) of Seoul National University has proposed a method for densely storing data by "poking" with a sharp probe. This method utilizes a material in the metastable state, whose properties change easily even with slight stimulation.

A thin film of metastable ferroelectric calcium titanate (CaTiO3) enables the polarization switching of a material even with a slight pressure of a probe: A very weak force of 100 nanonewtons (nN) is more than enough. The joint research team succeeded in making the width of the polarization path smaller than 10 nm by using this force and found the way to dramatically increase the capacity of data storage. This is because the smaller the size of the path, the more data the single material can store.

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World's whitest paint now thinner than ever, ideal for vehicles
https://phys.org/news/2022-10-world-whi ... icles.html
by Jared Pike, Purdue University

The world's whitest paint—seen in this year's edition of Guinness World Records and "The Late Show With Stephen Colbert"—keeps surfaces so cool that it could reduce the need for air conditioning. Now the Purdue University researchers who created the paint have developed a new formulation that is thinner and lighter—ideal for radiating heat away from cars, trains and airplanes.

"I've been contacted by everyone from spacecraft manufacturers to architects to companies that make clothes and shoes," said Xiulin Ruan, a Purdue professor of mechanical engineering and developer of the paint. "They mostly had two questions: Where can I buy it, and can you make it thinner?"

The original world's whitest paint used nanoparticles of barium sulfate to reflect 98.1% of sunlight, cooling outdoor surfaces more than 4.5°C below ambient temperature. Cover your roof in that paint, and you could essentially cool your home with much less air conditioning. But there's a problem.

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Researchers study exciton dynamics at unprecedented resolution
https://phys.org/news/2022-10-exciton-d ... ution.html
by University of Tsukuba

Future optical communication that's vastly more reliable and faster than what's commonly available today will require new technology. Modern communication is based on charge transfer, which can result in large transmission losses during certain data-intensive applications. Excitons are alternatives, yet they face technical challenges for widespread implementation.

Now, researchers from Japan have overcome a critical bottleneck that might give rise to ultrafast optical communication technology based on excitons. Their results are published in npj 2D Materials and Applications

Researchers are excited about using excitons—assemblies of bound electrons and holes—for terabits per second optical communication. Unfortunately, rapid exciton dissociation at room temperature in conventional three-dimensional semiconductors precludes immediate practical applications. However, atomically thin layered two-dimensional materials (transition metal dichalcogenides, TMDCs) impart certain advantages.

For example, in TMDCs, excitons can be stable at room temperature and can travel long distances. Local, ultrasmall-scale defects are inevitable in TMDCs—yet might even be advantageous if researchers can understand the role of such defects on the dynamics of exciton transport, and thus the properties of TMDC-based devices.

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Scientists use surfactant to help make 'inert' templates for nanotube growth
https://phys.org/news/2022-10-scientist ... otube.html
by Tokyo Metropolitan UniversityTokyo Metropolitan University

Researchers from Tokyo Metropolitan University have used a surfactant to disperse insulating boron nitride nanotubes and coat them onto surfaces without bundling. The team demonstrated that heat treatment could remove the surfactant to reveal clean nanoscale templates; chemical vapor deposition could then form coaxial nanotubes on the template using a range of materials. The ability to coat nanotubes onto "inert" insulating structures gives scientists unprecedented access to the properties of new nanotube materials.

Breakthroughs in nanotechnology have made nanotubes and nanosheets easier to come by for materials scientists. But studying them in isolation is far from easy. Because they often come bundled or aggregated, it's tricky to target the exotic optical and electronic properties that come from their reduced dimensionality.

Recent work showed that nanotube materials could be grown on the surface of a carbon nanotube, providing well-separated structures that could potentially be characterized. But carbon nanotubes have conducting properties and strongly absorb light, making it difficult to tell apart the electrical and optical properties of the coated material from those of the original nanotube.

Now, a team led by Assistant Professor Yusuke Nakanishi, Assistant Professor Yohei Yomogida, and Associate Professor Yasumitsu Miyata from Tokyo Metropolitan University has used insulating boron nitride (BN) nanotubes instead as templates for growing nanotubes. This is no mean task: boron nitride nanotubes are notoriously sticky. Though they can be dispersed with a surfactant which helps keeps the tubes apart, it was not clear whether the surfactant could be removed to reveal a clean template. Now, the team has successfully found a surfactant that does not stick to the tubes; they also honed a heat treatment under vacuum which leaves clean, well-isolated insulating nanotube templates.

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Self-assembled nanoscale architectures could feature improved electronic, optical, and mechanical properties
https://phys.org/news/2022-11-self-asse ... ronic.html
by Karen McNulty Walsh, Brookhaven National Laboratory

Scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have developed a new way to guide the self-assembly of a wide range of novel nanoscale structures using simple polymers as starting materials. Under the electron microscope, these nanometer-scale structures look like tiny Lego building blocks, including parapets for miniature medieval castles and Roman aqueducts. But rather than building fanciful microscopic fiefdoms, the scientists are exploring how these novel shapes might affect a material's functions.

The team from Brookhaven Lab's Center for Functional Nanomaterials (CFN) describes their novel approach to control self-assembly in a paper just published in Nature Communications. A preliminary analysis shows that different shapes have dramatically different electrical conductivity. The work could help guide the design of custom surface coatings with tailored optical, electronic, and mechanical properties for use in sensors, batteries, filters, and more.

"This work opens the door to a wide range of possible applications and opportunities for scientists from academia and industry to partner with experts at CFN," said Kevin Yager, leader of the project and CFN's Electronic Nanomaterials group. "Scientists interested in studying optical coatings, or electrodes for batteries, or solar cell designs could tell us what properties they need, and we can select just the right structure from our library of exotic shaped materials to meet their needs."

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Chemists create nanomachines by breaking them apart
https://phys.org/news/2023-02-chemists- ... hines.html
by University of Montreal

"Every act of creation," Picasso famously noted, "is first an act of destruction."

Taking this concept literally, researchers in Canada have now discovered that "breaking" molecular nanomachines basic to life can create new ones that work even better.

Their findings are published today in Nature Chemistry.
Evolved over millions of years

Life on Earth is made possible by tens of thousands of nanomachines that have evolved over millions of years. Often made of proteins or nucleic acids, they typically contain thousands of atoms and are less than 10,000 times the size of a human hair.

"These nanomachines control all molecular activities in our body, and problems with their regulation or structure are at the origin of most human diseases," said the new study's principal investigator Alexis Vallée-Bélisle, a chemistry professor at Université de Montréal.

Studying the way these nanomachines are built, Vallée-Bélisle, holder of the Canada Research Chair in Bioengineering and Bio-Nanotechnology, noticed that while some are made using a single component or part (often long biopolymers), others use several components that spontaneously assemble.

"Since most of my students spend their lives creating nanomachines, we started to wonder if it is more beneficial to create them using one or more self-assembling molecular components," said Vallée-Bélisle.

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Make them thin enough, and antiferroelectric materials become ferroelectric
https://phys.org/news/2023-02-thin-anti ... ctric.html
by Matt Shipman, North Carolina State University

Antiferroelectric materials have electrical properties that make them advantageous for use in high-density energy storage applications. Researchers have now discovered a size threshold beyond which antiferroelectrics lose those properties, becoming ferroelectric.

"Electronic devices are getting smaller and smaller, which makes it increasingly important for us to understand how a material's properties may change at small scales," says Ruijuan Xu, corresponding author of a paper on the work and an assistant professor of materials science and engineering at North Carolina State University.

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Scientists develop graphene aerogel particles for efficient water purification
https://phys.org/news/2023-02-scientist ... cient.html
by University of Manchester

Writing in the Journal of Molecular Liquids, a team led by Professor Aravind Vijayaraghavan based in the National Graphene Institute (NGI) have produced three-dimensional particles made of graphene, of many interesting shapes, using a variation of the vortex ring effect. The same effect is used to produce smoke rings and is responsible for keeping dandelion seeds flying. These particles have also been shown to be exceptionally efficient in adsorbing contaminants from water, thereby purifying it.

The researchers have shown that the formation of these graphene particles is governed by a complex interplay between different forces such as viscosity, surface tension, inertia and electrostatics. Prof Vijayaraghavan said, "We have undertaken a systematic study to understand and explain the influence of various parameters and forces involved in the particle formation. Then, by tailoring this process, we have developed very efficient particles for adsorptive purification of contaminants from water."

Graphene oxide (GO), a functionalized form of graphene that forms a stable dispersion in water, has many unique properties, including being a liquid crystal. Individual GO sheets are one atom thin, and as wide as the thickness of human hair. However, to be useful, they need to be assembled into complex 3-dimensional shapes that preserves their high surface area and surface chemistry. Such porous 3-dimensional assemblies of GO are called aerogels, and when filled with water, they are called hydrogels.

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Researchers develop novel nonwovens that are electrically conductive but thermally insulating

by Bayreuth University

Researchers at the University of Bayreuth present novel electrospun nonwovens in Science Advances that exhibit an unusual combination of high electrical conductivity and extremely low thermal conductivity.

The nonwovens represent a breakthrough in materials research: it has been possible to decouple electrical and thermal conductivity based on a simple-to-implement material concept. The nonwovens are made of carbon and silicon-based ceramic via electrospinning process and are attractive for technological applications, for example, in energy technology and electronics. They can be manufactured and processed cost-effectively on an industrial scale.

https://phys.org/news/2023-04-nonwovens ... ating.html

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Revolutionary Phase Change Nano Inks: The Future of Energy-Efficient Climate Control in Buildings & Cars
https://scitechdaily.com/revolutionary- ... ings-cars/

By University of Melbourne April 5, 2023
Phase Change Inks

Phase change inks using nanotechnology have been developed to control temperature and provide passive climate control, reducing energy consumption. The versatile inks have potential applications in buildings, electronics, and clothing, and could become a sustainable solution to address climate change.

World-first ‘phase change inks’ that could transform how we heat and cool buildings, homes, and cars – to achieve sophisticated ‘passive climate’ control – have been developed, with enormous potential to help reduce energy use and global greenhouse gas emissions.

New research published in The Royal Society of Chemistry’s Journal of Materials Chemistry A led by Dr. Mohammad Taha, documents proof-of-concept ‘phase change inks’ that use nanotechnology to control the temperature in everyday environments. They achieve this by adjusting the amount of radiation that can pass through them, based on the surrounding environment.

Dr. Taha said these inks could be used to develop coatings to achieve passive heating and cooling, reducing our need to rely on energy creation to regulate temperatures.

“Humans use a lot of energy to create and maintain comfortable environments – heating and cooling our buildings, homes, cars, and even our bodies,” Dr. Taha said.

“We can no longer only focus on energy generation from renewable resources to reduce our environmental impact. We also need to consider reducing our energy consumption as part of our proposed energy solutions, as the impacts of climate change become a reality.

“By engineering our inks to respond to their surroundings, we not only reduce the energy expenditure, but we also remove the need for auxiliary control systems to control temperatures, which is an additional energy waste.”

Passive climate control would enable comfortable living conditions without expending energy unnecessarily. For example, to provide comfortable heating in winter, the inks applied on a building façade could automatically transform to allow greater sun radiation to pass through during the day, and greater insulation to keep warmth in at night. In summer, they could transform to form a barrier to block heat radiation from the sun and the surrounding environment.

The versatile ‘phase change inks’ are a proof-of-concept that can be laminated, sprayed or added to paints and building materials. They could also be incorporated into clothing, regulating body temperature in extreme environments, or in the creation of large-scale, flexible and wearable electronic devices like bendable circuits, cameras and detectors, and gas and temperature sensors.

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Team develops the world's smallest and fastest nano-excitonic transistor

by Pohang University of Science and Technology
https://phys.org/news/2023-04-team-worl ... tonic.html

How can Marvel movie character Ant-Man produce such strong energy out of his small body? The secret lies in the transistors on his suit that amplify weak signals for processing. Transistors that amplify electrical signals in the conventional way lose heat energy and limit the speed of signal transfer, which degrades performance. What if it were possible to overcome such limitations and make a high-performance suit that is light and small but without the loss of heat energy?

A POSTECH team of Professor Kyoung-Duck Park and Yeonjeong Koo from the Department of Physics and a team from ITMO University in Russia led by Professor Vasily Kravtsov jointly developed a nano-excitonic transistor using intralayer and interlayer excitons in heterostructure-based semiconductors, which addresses the limitations of existing transistors. The research was recently published in the journal ACS Nano.

Excitons are responsible for light emission of semiconductor materials and are key to developing a next-generation light-emitting element with less heat generation and a light source for quantum information technology due to the free conversion between light and material in their electrically neutral states.

There are two types of excitons in a semiconductor heterobilayer, which is a stack of two different semiconductor monolayers: the intralayer excitons with horizontal direction and the interlayer excitons with vertical direction.

Optical signals emitted by the two excitons have different lights, durations, and coherence times. This means that selective control of the two optical signals could enable the development of a two-bit exciton transistor. However, it was challenging to control intra- and interlayer excitons in nano-scale spaces due to the non-homogeneity of semiconductor heterostructures and low luminous efficiency of interlayer excitons in addition to the diffraction limit of light.

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Thinnest-ever freestanding film with ferroelectric properties
https://phys.org/news/2023-04-thinnest- ... rties.html
by Nagoya University

Researchers at the Institute for Future Materials and Systems at Nagoya University in Japan have successfully synthesized barium titanate (BaTiO3) nanosheets with a thickness of 1.8 nanometers, the thinnest thickness ever created for a free-standing film. Given that thickness is related to functionality, their findings open the door to smaller, more efficient devices. The research was published in the journal Advanced Electronic Materials.

The development of ever-thinner materials with new electronic functions is a highly competitive area of research. Such devices are especially important in ferroelectrics, materials that have a polarization that can be reversed by an electric field. This ability to reverse polarization makes these materials useful in memory and vibrational power generation.

However, as the materials used in these devices become smaller, they exhibit unexpected properties that complicate their industrial use. A big problem is the "size effect," as when the material's thickness is reduced to a few nanometers, its ferroelectric properties disappear.

[caltrek]

Nanotech Can Peek Inside Viruses and Detect Imperfections in Tiny Computer Chips
by Kendra Leon
April 26, 2023

Introduction:

(Courthouse News) — New nanotechnology created by the Australian National University can access light sources that are unseeable by the human eye and detect objects smaller than conventional microscopes can.

Cameras and other technologies already unveil low-frequency infra-red and high-frequency ultraviolet lights, but the Australian National University technology, developed in collaboration with the University of Brescia, the University of Arizona, and Korea University, can detect the very high frequencies of light called extreme-ultraviolet.

The nanotech increases light frequencies that other technologies see by up to seven times with 10 times the resolution, according to a study published in Science Advances Wednesday.

By using light to peer at objects thousands of times smaller than a human hair, co-author Dr. Sergey Kruk of Australian National university said via email that the nanotech avoids the risk of damaging samples the way electron microscopes do.

Conclusion:

“We hope the pursuit of this emerging direction of research will be increasing internationally, and the focus will be moving beyond fundamental principles towards applied research and development of such light sources for specific applications. As the next milestone, I hope to see collaborative projects with medical and biological researchers and with researchers of semiconductor foundries,” Kruk said.

Read more here: https://www.courthousenews.com/new-nan ... udy-says/

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Researchers observe extremely squeezed directional THz waves in thin semiconductor crystals
https://phys.org/news/2023-05-extremely ... stals.html
by Elhuyar Fundazioa

An international team of scientists has imaged and analyzed THz waves that propagate in the form of plasmon polaritons along thin anisotropic semiconductor platelets with wavelengths reduced by up to 65 times compared to THz waves in free space.

What's even more intriguing is that the wavelengths vary with the direction of propagation. Such THz waves can be applied for probing fundamental material properties at the nanometer scale and pave the way to the development of ultra-compact on-chip THz devices. The work has been published in Nature Materials.

Polaritons are hybrid states of light and matter that arise from the coupling of light with matter excitations. Plasmon and phonon polaritons are among the most prominent examples, formed by the coupling of light to collective electron oscillations and crystal lattice vibrations, respectively.

They play a crucial role in various applications, from sub-diffraction optical spectroscopy and ultrasensitive chemical sensors to ultracompact modulators for communication applications. In thin layers, polaritons can propagate with wavelengths up to 100 times shorter than the corresponding photon wavelength, allowing for manipulation of light on a much smaller scale than previously possible with conventional photonic devices.

While most of these ultra-confined polaritons have been observed in form of phonon polaritons in the mid-infrared spectral range, the researchers focused on plasmon polaritons, as these can exist in much broader spectral ranges. "On the other hand, plasmon polaritons often suffer from large damping, resulting in short propagation lengths. This has been challenging the observation of ultra-confined plasmon polaritons in real space," says Shu Chen, first author of the publication.

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Engineering self-integrated atomic quantum wires to form nano-networks
https://phys.org/news/2023-05-self-inte ... works.html
by Thamarasee Jeewandara , Phys.org

Quantum advances rely on the production of nanoscale wires that are based on several state-of-the-art nanolithographic technologies, to develop wires via bottom-up synthesis. However, a critical challenge is to grow uniform atomic crystalline wires and construct network structures to build nanocircuits.

In a new report in Science Advances, Tomoya Asaba and a team of researchers in physics and materials science at the Kyoto University, the University of Tokyo in Japan, and the Institute of Theoretical Physics in Germany, discovered a simple method to develop atomic-scale wires in the shape of nano-rings, stripes and X-/Y- junctions.

Using pulsed-laser-deposition, the physicists and materials scientists grew single crystalline, atomic-scale wires of a Mott insulator, which maintained a bandgap comparable to wide-gap semiconductors. Such wires were a unit cell in thickness and a few microns in length. The researchers observed atomic pattern formation through non-equilibrium reaction-diffusion processes to offer a hitherto unknown perspective on the phenomena of atomic-scale self-organization to gain insight to the formation of quantum architecture in nano-networks.
New methods to engineer atomic-scale nanowires

The basic features of most technical devices change when their dimensions are reduced. When a device is reduced to the nanoscale, the fabrication and integration of one-dimensional wire patterns become increasingly complex. Developing top-down approaches with large-scale equipment such as electron beam and focused ion beam lithography to include nanowires with a thickness and width less than 10 nanometers is another technical challenge.