Categorie: Materiale noi cu proprietati fizicomecanice noi

O privire apropiată asupra nanomaterialelor ultra-subțiri pentru uz industrial (A close up look at ultra-thin nanomaterials for industrial use )

Nanomaterialele bidimensionale (2D) constau din straturi ultra-subțiri, care pot fi la fel de subțiri ca un singur atom. Natura ultra-subțire a nanomaterialelor 2D le conferă proprietăți speciale, cum ar fi rapoartele de suprafață ridicate și proprietățile termice și electronice excepționale. Acest lucru a pus în evidență aplicații în domeniul electronicii moderne, al stocării și al recoltării energiei.

Postat: Jul 05, 2016

O privire apropiată asupra nanomaterialelor ultra-subțiri pentru uz industrial

( Nanowerk News ) Avansurile în nanomateriale țin promisiunea unor produse noi, mai bune și mai competitive. Proiectul 2DInterFOX finanțat de UE caută noi perspective asupra comportamentului lor – rezultatele ar putea ajuta producătorii să dezvolte noi produse electronice și legate de consumul de energie, potențiali care să le stimuleze competitivitatea.
nanomateriale
În timp ce potențialul nanomaterialelor și nanotehnologiilor este bine documentat, traducerea științei celor foarte mici în succesul comercial a fost un proces dificil.
Nanomaterialele bidimensionale (2D) constau din straturi ultra-subțiri, care pot fi la fel de subțiri ca un singur atom. Natura ultra-subțire a nanomaterialelor 2D le conferă proprietăți speciale, cum ar fi rapoartele de suprafață ridicate și proprietățile termice și electronice excepționale. Acest lucru a pus în evidență aplicații în domeniul electronicii moderne, al stocării și al recoltării energiei.
Spre deosebire de materialele tradiționale în vrac, există mai mulți atomi pe suprafața unui material 2D decât în ​​mijlocul acestuia. Atomii de suprafață acționează diferit față de atomii din interiorul unui material, deci atunci când există mai mulți atomi de suprafață decât atomii din interiorul lor, modul în care se comportă afectează modul în care se comportă un material.
Cu toate acestea, multe sunt încă necunoscute despre materialele 2D la nivel atomic și, în special, despre interacțiunea materialelor 2D cu alte nanomateriale.
2DInterFOX va încerca să ofere răspunsuri cu privire la interacțiunile dintre nanomaterialele 2D și materialele non-metalice de oxid 2D care sunt utilizate în industria electronică și în domeniul energetic. Aceste informații ar putea ajuta industria să mărească integrarea nanomaterialelor 2D cu alte tipuri de nanostructuri. O asemenea descoperire ar putea fi utilizată în aplicații electronice flexibile, transparente, cu costuri reduse sau în sectorul energetic.
2DInterFOX propune utilizarea tehnicilor de scanare electronică prin microscopie electronică (STEM), prin care se transmite un fascicul de electroni printr-o mostră ultra-subțire, pentru a crea o imagine a structurii eșantionului la nivel atomic și pentru a afla mai multe despre interacțiunile chimice și electronice ale Materialele 2D cu nanostructuri de oxid de metal.
Sursa: Comisia Europeană

Read more: A close up look at ultra-thin nanomaterials for industrial use

Materialul plastic nou începe să oscileze în mod spontan în lumina soarelui (New plastic material begins to oscillate spontaneously in sunlight )

Provocarea a fost găsirea unui material care se comportă în acest fel în lumină vizibilă, de preferință lumina solară neprelucrată.au reușit acum să producă un strat de polimer subțire care conține molecule sensibile la lumină (azo-coloranți).Una dintre principalele posibilități de utilizare a materialului este ca suprafață autocurătoare.

Posted: Jul 05, 2016

New plastic material begins to oscillate spontaneously in sunlight

(Nanowerk News) Materials that move all by themselves under the influence of light – this phenomenon has been known for a number of years. However, since the source tends to be ultraviolet light, the required intensity can damage the material. The challenge was to find a material that behaves in this way in visible light, preferably unprocessed sunlight.
The researchers from Eindhoven and Berlin have now succeeded in producing a thin polymer layer containing light-sensitive molecules (azo-dyes). Lying in sunlight, the thin film begins to oscillate spontaneously and irregularly (Nature Communications, „A chaotic self-oscillating sunlight-driven polymer actuator”).
Plastic Begins to Oscillate Spontaneously
Why the plastic begins to oscillate spontaneously is something that the researchers cannot yet quite explain. (Image: Eindhoven University of Technology)
Combination of factors
Why the plastic does this is something that the researchers cannot yet quite explain. „It seems to be a combination of factors,” suggests TU/e researcher Michael Debije. „The light-sensitive molecules bend and stretch under the influence of visible light. Since these molecules are bound within the polymer network of crystal, this results in the material oscillating as if cramped. Of course, there’s more to it than that – this is what we are investigating now.”
Self-cleaning
One of the main possibilities for using the material is as a self-cleaning surface. „A surface that vibrates in the sun makes it difficult for sand and dust to stick to it,” Debije says. Fellow researcher, Dick Broer, thinks that self-cleaning solar panels in the desert where there are no water supplies could be an option. But the researchers believe there is a whole range of other possible applications.
„We have just discovered the effect; we expect that this will attract attention from many researchers from whom we will be hearing a lot over the coming period,” Debije says.
Source: Eindhoven University of Technology

Read more: New plastic material begins to oscillate spontaneously in sunlight

Trioul integrat de nanomateriale 2D deblochează aplicațiile electronice grafen (Integrated trio of 2D nanomaterials unlocks graphene electronics applications )

Conductibilitatea termică extrem de ridicată a grafenului este un avantaj suplimentar în structura dispozitivului prin facilitarea eliminării căldurii. Proprietățile unice de conducție termică ale grafenului au fost descoperite experimental și explicate teoretic în 2008

Posted: Jul 05, 2016

Integrated trio of 2D nanomaterials unlocks graphene electronics applications

(Nanowerk News) Graphene has emerged as one of the most promising two-dimensional crystals, but the future of electronics may include two other nanomaterials, according to a new study by researchers at the University of California, Riverside and the University of Georgia.
In research published Monday (July 4) in the journal Nature Nanotechnology („A charge-density-wave oscillator based on an integrated tantalum disulfide–boron nitride–graphene device operating at room temperature”), the researchers described the integration of three very different two-dimensional (2D) materials to yield a simple, compact, and fast voltage-controlled oscillator (VCO) device. A VCO is an electronic oscillator whose oscillation frequency is controlled by a voltage input.
integrated Tantalum Sulfide—Boron Nitride—Graphene Oscillator
A schematic of the integrated Tantalum Sulfide—Boron Nitride—Graphene Oscillator developed at UCR, which is the first useful device that exploits the potential of charge-density waves to modulate an electrical current through a 2D material.
The paper describes the development of the first useful device that exploits the potential of charge-density waves to modulate an electrical current through a 2D material. The new technology could become an ultralow power alternative to conventional silicon-based devices, which are used in thousands of applications from computers to clocks to radios. The thin, flexible nature of the device would make it ideal for use in wearable technologies.
Graphene, a single layer of carbon atoms that exhibits exceptional electrical and thermal conductivities, shows promise as a successor to silicon-based transistors. However, its application has been limited by its inability to function as a semiconductor, which is critical for the ‘on–off’ switching operations performed by electronic components.
To overcome this shortfall, the researchers turned to another 2D nanomaterial, Tantalum Sulfide (TaS2). They showed that voltage-induced changes in the atomic structure of the ‘1T prototype’ of TaS2 enable it to function as an electrical switch at room temperature—a requirement for practical applications.
“There are many charge-density wave materials that have interesting electrical switching properties. However, most of them reveal these properties at very low temperature only. The particular polytype of TaS2 that we used can have abrupt changes in resistance above room temperature. That made a crucial difference,” said Alexander Balandin, UC presidential chair professor of electrical and computer engineering in UCR’s Bourns College of Engineering, who led the research team.
To protect the TaS2 from environmental damage, the researchers coated it with another 2D material, hexagonal boron nitrate, to prevent oxidation. By pairing the boron nitride-capped TaS2 with graphene, the team constructed a three-layer VCO that could pave the way for post-silicon electronics. In the proposed design, graphene functions as an integrated tunable load resistor, which enables precise voltage control of the current and VCO frequency. The prototype UCR devices operated at MHz frequency used in radios, and the extremely fast physical processes that define the device functionality allow for the operation frequency to increase all the way to THz.
Balandin said the integrated system is the first example of a functional voltage-controlled oscillator device comprising 2D materials that operates at room temperature. “It is difficult to compete with silicon, which has been used and improved for the past 50 years. However, we believe our device shows a unique integration of three very different 2D materials, which utilizes the intrinsic properties of each of these materials. The device can potentially become a low-power alternative to conventional silicon technologies in many different applications,” Balandin said.
The electronic function of graphene envisioned in the proposed 2D device overcomes the problem associated with the absence of the energy band gap, which so far prevented graphene’s use as the transistor channel material. The extremely high thermal conductivity of graphene comes as an additional benefit in the device structure, by facilitating heat removal. The unique heat conduction properties of graphene were experimentally discovered and theoretically explained in 2008 by Balandin’s group at UCR. The Materials Research Society recognized this groundbreaking achievement by awarding Balandin the MRS Medal in 2013.
The Balandin group also demonstrated the first integrated graphene heat spreaders for high-power transistors and light-emitting diodes. “In those applications, graphene was used exclusively as heat conducting material. Its thermal conductivity was the main property. In the present device, we utilize both electrical and thermal conductivity of graphene,” Balandin added.
Source: University of California, Riverside

Read more: Integrated trio of 2D nanomaterials unlocks graphene electronics applications

Laser manipulează proprietățile electronice(Laser manipulates electronic properties)

Un material semiconductor nou, care are doar trei straturi atomice groase, a apărut cu proprietăți electronice mai exotice, maleabile decât cele ale semiconductorilor tradiționali.Un nou material semiconductor ultra-subțire (disulfură de wolfram sau WS 2 ) constă din trei straturi atomice într-o configurație „sandwich atomică”, cu un strat de atomi de tungsten de metal greu între straturile de atomi de sulf mai ușori. Materialul este cvasi-dimensional, are doar trei atomi grosime și prezintă o structură electronică unică, cu diferențe subtile, în funcție de direcția în raport cu legăturile atomice repetate în planul stratului.

Posted: Jun 17, 2016

Laser manipulates electronic properties

(Nanowerk News) A new semiconducting material that is only three atomic-layers thick has emerged with more exotic, malleable electronic properties than those of traditional semiconductors. These properties come from electrons, like a ball rolling down a hill to a valley, that prefer the lower energy levels at the bottom of electronic energy “valleys”. Now, the valley depth can be shifted optically and with extreme speed with sculpted laser pulses (Nature Materials, „Valley-selective optical Stark effect in monolayer WS2„).
Electrons have distinct energy levels where the energy is minimized, similar to a ball rolling down a mountain to a valley
Electrons have distinct energy levels where the energy is minimized, similar to a ball rolling down a mountain to a valley. In the artistically enhanced depiction, a valley in the electronic structure interacts with and is controllably manipulated by circularly polarized laser light. The laser causes valleys with initially equal energies to have slightly different energies. This is the first time a laser has separated energy valleys in an atomically thin semiconductor (tungsten disulfide), which could lead to advanced electronics based on energy valley states instead of conventional electronics based on charge flows and accumulation. (Image: Massachusetts Institute of Technology. Illustration by Ella Marushchenko and Alex Tokarev)
Layered materials where electrons are constrained to two dimensions can be engineered into novel electronic structures with unique electronic and optical properties. Optical manipulation of electrons can lead to new modes of energy conversion and computational devices such as electronics based on energy valleys states instead of conventional electronics based on charge flows and accumulation.
A new ultra-thin semiconducting material (tungsten disulfide or WS2) consists of three atomic layers in an “atomic sandwich” configuration with a heavy metal tungsten atom layer between lighter element sulfur atom layers. The material is quasi-two dimensional, just three atoms thick, and exhibits a unique electronic structure with subtle differences depending on the direction relative to the repeating atomic bonds in the layer plane.
The differences create two distinct but similar valleys in the electronic structure, where electrons can accumulate with different directions, but with associated energy levels and gaps that are equal. Adding a specific type of laser beam, where the polarization direction (the direction of interacting electric forces) rotates as the light propagates, creates a new type of electron energy structure that can be probed and manipulated.
The electron structural landscape, which began with two similar valleys, can also be made to have different distinct valleys with different energy depths. The valley depth can now be manipulated with light to encode information like zeroes and ones for conventional data.
Additionally, changing the energy of the valleys with light allows for fast manipulation without the need for contact with complex electrodes as in conventional electronics.
Source: Department of Energy, Office of Science

Graphene nu este singurul Lego din caseta de jucării pentru materiale științifice din domeniul nanoelectronicii(Graphene isn’t the only Lego in the nanoelectronics materials-science toy box

disulfidul de molibden (MoS 2 ), este un material cu un singur strat, cu proprietăți interesante dincolo de cele ale grafenului. MoS 2 poate absorbi de cinci ori mai multă lumină vizibilă ca grafenul, făcându-l util în detectoarele de lumină și celulele solare. În plus, se propun și se sintetizează zilnic și materiale mai noi, cum ar fi borofenul (un material cu un singur strat format din atomi de bor proiectat a fi mecanic mai puternic decât grafenul).

Posted: Jun 15, 2016

Graphene isn’t the only Lego in the nanoelectronics materials-science toy box

(Nanowerk News) You may have heard of graphene, a sheet of pure carbon, one atom thick, that’s all the rage in materials-science circles, and getting plenty of media hype as well. Reports have trumpeted graphene as an ultra-thin, super-strong, super-conductive, super-flexible material. You could be excused for thinking it might even save all of humanity from certain doom.
Not exactly. In the current world of nano-electronics, there is a lot more going on than just graphene. One of the materials I work with, molybdenum disulphide (MoS2), is a one-layer material with interesting properties beyond those of graphene. MoS2 can absorb five times as much visible light as graphene, making it useful in light detectors and solar cells. In addition, even newer materials like borophene (a one-layer material made of boron atoms projected to be mechanically stronger than graphene) are being proposed and synthesized every day.
Layering two-dimensional materials
Layering two-dimensional materials. (Image: Peter Byrley)
These and other materials yet to be discovered will be used like Lego pieces to build the electronics of the future (the paper is titled van der Waals heterostructures). By stacking multiple materials in different ways, we can take advantage of different properties in each of them. The new electronics built with these combined structures will be faster, smaller, more environmentally resistant and cheaper than what we have now.
Looking for an energy gap
There is a key reason that graphene will not be the versatile cure-all material that the hype might suggest. You can’t just stack graphene repeatedly to get what you want. The electronic property preventing this is the lack of what is called an “energy gap.” (The more technical term is “band gap.”)
Metals will conduct electricity through them regardless of the environment. However, any other material that is not a metal needs a little boost of energy from the outside to get electrons to move through the band gap and into the conducting state. How much of a boost the material needs is called the energy gap. The energy gap is one of the factors that determines how much total energy needs to be put into your entire electrical device, from either heat or applied electrical voltage, to get it to conduct electricity („Physics of Semiconductor Devices”). You essentially have to put in enough starting energy if you want your device to work.
Some materials have a gap so large that almost no amount of energy can get electrons flowing through them. These materials are called insulators (think glass). Other materials have either an extremely small gap or no gap at all. These materials are called metals (think copper). This is why we use copper (a metal with instant conductivity) for wiring, while we use plastics (an insulator that blocks electricity) as the protective outer coating.
Everything else, with gaps in between these two extremes, is called a semiconductor (think silicon). Semiconductors, at the theoretical temperature of absolute zero, behave as insulators because they have no heat energy to get their electrons into the conducting state. At room temperature, however, heat from the surrounding environment provides just enough energy to get some electrons (hence the term, “semi”-conducting) over the small band gap and into the conducting state ready to conduct electricity.
Comparing the band gap in metals (left), semiconductors (center) and insulators (right)
Comparing the band gap in metals (left), semiconductors (center) and insulators (right). (Image: Peter Byrley)
Graphene’s energy gap
Graphene is in fact a semi-metal. It has no energy gap, which means it will always conduct electricity – you can’t turn off its conductivity.
This is a problem because electronic devices use electrical current to communicate. At their most fundamental level, computers communicate by sending 1’s and 0’s – on and off signals. If a computer’s components were made from graphene, the system would always be on, everywhere. It would be unable to perform tasks because its lack of energy gap prevents graphene from ever becoming a zero; the computer would keep reading 1’s all the time. Semiconductors, by contrast, have an energy gap that is small enough to let some electrons conduct electricity but is large enough to have a clear distinction between on and off states.
Finding the right materials
Not all hope is lost, however. Researchers are looking at three main ways to tackle this:
  • Using new materials similar to graphene that actually have a sufficient energy gap and finding ways to further improve their conductivity.
  • Altering graphene itself to create this energy gap.
  • Combining graphene with other materials to optimize their combined properties.
There are many one-layer materials currently being looked at that actually have a sufficient energy gap. One such material, MoS2, has been studied in recent years as a potential replacement for traditional silicon and also as a light detector and gas sensor.
The only drawback with these other materials is that so far, we have not found one that matches the excellent though always-on conductivity of graphene. The other materials can be turned off, but when on, they are not as good as graphene. MoS2 itself is estimated to have 1/15th to 1/10th the conductivity of graphene in small devices. Researchers, including me, are now looking at ways to alter these materials to increase their conductivity.
Using graphene as an ingredient
Strangely, an energy gap in graphene can actually be induced through modifications like bending it, turning it into a nanoribbon, inserting foreign chemicals into it or using two layers of graphene. But each of these modifications can reduce the graphene’s conductivity or limit how it can be used.
To avoid specialized setups, we could just combine graphene with other materials. By doing this, we are also combining the properties of the materials in order to reap the best benefits. We could, for example, invent new electronic components that have a material allowing them to be shut off or on (like MoS2) but have graphene’s great conductivity when turned on. New solar cells will work on this concept.
A combined structure could, for example, be a solar panel made for harsh environments: We could layer a thin, transparent protective material over the top of a very efficient solar-collecting material, which in turn could be on top of a material that is excellent at conducting electricity to a nearby battery („Extraordinary Sunlight Absorption and One Nanometer Thick Photovoltaics Using Two-Dimensional Monolayer Materials”). Other middle layers could include materials that are good at selectively detecting gases such as methane or carbon dioxide.
Researchers are now racing to figure out what the best combination is for different applications. Whoever finds the best combination will eventually win numerous rights to patents for improved electronic products.
The truth is, though, we don’t know what our future electronics will look like. New Lego pieces are being invented all the time; the ways we stack or rearrange them are changing constantly, too. All that’s certain is that the insides of electronic devices will look drastically different in the future than they do today.
Source: By Peter Byrley, Ph.D. Candidate in Chemical Engineering, University of California, Riverside

Amestecarea solidelor și a lichidelor sporește proprietățile optice ale ambelor( Mixing solids and liquids enhances optical properties of both )

Fluidul și sticla din prototip au fost alese deoarece au indicatori de refracție foarte asemănăți, ceea ce înseamnă că lumina trece prin ele cu viteze similare. Atunci când lumina se mișcă dintr-un material cu un indice de refracție ridicat la unul cu un indice de refracție mai mic, acesta schimbă direcția; acesta este fenomenul din spatele iluziei familiare a apariției unei paie care se îndoaie când este introdusă într-un pahar de apă.
Prototipul cercetătorilor exploatează faptul că schimbările de temperatură modifică indicii de refracție ai materialelor.În experimentele lor, cercetătorii au descoperit că o schimbare de temperatură de 10 grade ar crește de zece ori difuzia dispozitivului și o schimbare de 42 de grade a schimbat-o de o mie de ori.
Heshmat crede că o versiune modulate în funcție de temperatură a filtrului echipei sale ar putea fi utilizată pentru calibrarea senzorilor utilizați în studiul fluxurilor materiale, studiul celulelor și imagistica medicală.

Posted: Jun 09, 2016

Mixing solids and liquids enhances optical properties of both

(Nanowerk News) By immersing glass particles in a fluid, researchers at MIT’s Media Lab and Harvard University are exploring a new mechanism for modifying an optical device’s diffusivity, or the extent to which it scatters light.
In its current form, the new diffuser could be used to calibrate a wide range of imaging systems, but the researchers believe that their mechanism could ultimately lead to holographic video screens or to tunable optical devices with applications in imaging, sensing, and photography.
A mild temperature change radically alters the degree to which a solid-fluid mixture bends light
A mild temperature change radically alters the degree to which a solid-fluid mixture bends light. (Image: Courtesy of the researchers)
In experiments, the solid-liquid mixture demonstrated much more dramatic changes in diffusivity than existing theory would have predicted, so the researchers also developed a new computer model to describe it. That model could help them devise more complex applications for the basic technology.
The researchers describe their new work in the latest issue of the American Chemical Society’s ACS Photonics journal („Tyndall Windows: Tunable Scattering of Disordered Solid–Liquid Matching Mixtures”).
The fluid and the glass in the prototype were chosen because they have very similar refractive indices, meaning light travels through them at similar speeds. When light moves from a material with a high refractive index to one with a lower refractive index, it changes direction; this is the phenomenon behind the familiar illusion of a straw’s appearing to bend when it’s inserted into a glass of water.
The researchers’ prototype exploits the fact that changes in temperature alter materials’ refractive indices.
“It’s hard to find a solid and liquid that have exactly the same refractive index at room temperature,” says Barmak Heshmat, a postdoc in the Media Lab’s Camera Culture group and corresponding author on the paper. “But if the speed at which the refractive index changes for solid and liquid is different — which is the case for most solids and liquids — then at a certain temperature they will exactly match, to the last digit. That’s why you see this giant jump in transparency.”
Changing the diffusivity of a solid-fluid mixture renders the letters MIT legible or illegible
Changing the diffusivity of a solid-fluid mixture renders the letters „MIT” legible or illegible. Inset: the glass particles suspended in the mixture. (Image: Courtesy of the researchers)
Heshmat is joined on the paper by Ramesh Raskar, the NEC Career Development Associate Professor of Media Arts and Sciences and head of the Camera Culture group, and Benedikt Groever, a graduate student in engineering and applied science at Harvard.
Study in contrast
In their experiments, the researchers found that a temperature change of 10 degrees would increase the diffusivity of their device tenfold, and a change of 42 degrees changed it a thousandfold.
Heshmat believes that a temperature-modulated version of his team’s filter could be used to calibrate sensors used in the study of material flows, the study of cells, and medical imaging.
For instance, medical-imaging systems are typically calibrated using devices called “tissue phantoms,” which duplicate the optical properties of different types of biological tissues. Tissue phantoms can be expensive, and many of them may be required to calibrate a single imaging device. Heshmat believes that a low-cost version of his team’s filter could mimic a wide range of tissues.
But the fundamental principle illustrated by the researchers’ prototype could have broader ramifications. The effect of heat on the refractive index of either the solid or the fluid, taken in isolation, is very subtle. But when the two are mixed together, the effect on diffusivity is dramatic.
refractive indices of an optical fluid and glass particles suspended in it
At a certain temperature (b), the refractive indices of an optical fluid and glass particles suspended in it match, rendering the solid-fluid mixture transparent. At lightly lower (a) and higher (b) temperatures, the mismatch of refractive indices causes light to scatter. (Image: Courtesy of the researchers)
The same would be true, Heshmat argues, of other types experimental materials whose refractive indices change in response to either light or an electric field. And optical or electrical activation would broaden the range of applications for tunable optical devices.
“If you have photorefractive changes in a solid material in a solid phase, the amount of change you can get between the solid and itself is very small,” he explains. “You need a very strong field to see that change in your refractive index. But if you have two types of media, the refractive index of the solid is going to change much faster compared to the liquid. So you get this deep contrast that can help a lot.”
Application
In holographic displays, cells filled with a mixture of electrically responsive solid materials and a fluid could change their diffusivity when charged by an electrode, in much the way that cells filled with ionized gas change their color in plasma TVs. Adjacent cells could thus steer light in slightly different directions, mimicking the reflection of light off of a contoured surface and producing the illusion of three-dimensionality.
Liquid-solid mixtures could also be used to produce tunable diffraction gratings, which are used in some sensing applications to filter out light or other electromagnetic radiation of particular frequencies, or in tunable light diffusers of the sort photographers use to make the strongly directional light of a flash feel more like ambient light.
The computer model that the researchers describe in their paper predicts the diffusivity of a liquid-solid mixture on the basis of the physical characteristics of the solid particles — how jagged or spiky they are — and on their concentration in the liquid. That model, Heshmat says, could be used to develop solid particles tailored to specific applications.
The appeal of this method may even reach beyond science and engineering. “I understand the obvious potential scientific applications listed in the abstract,” says Aydogan Ozcan, a professor of electrical engineering at the University of California at Los Angeles. “But I think this kind of approach could potentially be useful for designing new artwork — for interior design, for example. You can design furniture parts or artwork that will change the light-matter interaction and visual perception on demand or through a programmed interface, which would bring dynamic light effects indoors. Similarly, it can be used in architectural designs to replace curtains by structured interfaces.”
Source: By Larry Hardesty, MIT

Read more: Mixing solids and liquids enhances optical properties of both

Acesta este diprosiul – dacă nu reușim, spuneți la revedere telefoanelor inteligente, scanărilor IRM și automobilelor hibride(This is dyprosium – if we run out of it, say goodbye to smartphones, MRI scans and hybrid cars)

Acestea sunt pământuri rare, un grup de 17 elemente chimice cu nume care leagă limba, cum ar fi ytriu și tuliu, care sunt folosite în televizoare, telefoane mobile, laptopuri
Cautati pentru proprietățile lor magnetice și conductive, ele fac tehnologiile mai rapide, mai puternice, mai ușoare și mai eficiente

This is

Stoarcerea culorilor asemănătoare opalului cu mile

intensă.
Prin schimbarea dimensiunilor nano-sferelor de pornire, se reflectă diferite culori (sau lungimi de undă) de lumină. Și deoarece materialul are o consistență asemănătoare cauciucului, atunci când este răsucite și întinse, distanța dintre sfere se schimbă, determinând materialul să schimbe culoarea. Când este întins, materialul se deplasează în gama albastră a spectrului, iar când este comprimat, culoarea se schimbă spre roșu. Când este eliberat, materialul revine la culoarea inițială. Astfel de materiale de chameleon s-ar putea să-și găsească drumul în imagini de fundal care schimbă culoarea sau în straturile de acoperire care reflectă radiația termică infraroșie.

Posted: Jun 03, 2016

Squeezing out opal-like colors by the mile (w/video)

(Nanowerk News) The team, led by the University of Cambridge, have invented a way to make such sheets on industrial scales, opening up applications ranging from smart clothing for people or buildings, to banknote security.
Using a new method called Bend-Induced-Oscillatory-Shearing (BIOS), the researchers are now able to produce hundreds of metres of these materials, known as ‘polymer opals’, on a roll-to-roll process. The results are reported in the journal Nature Communications („Large-scale ordering of nanoparticles using viscoelastic shear processing”).
Polymer Opals
Researchers at the University of Cambridge have devised a method to produce „Polymer Opals” on an industrial scale.
Some of the brightest colours in nature can be found in opal gemstones, butterfly wings and beetles. These materials get their colour not from dyes or pigments, but from the systematically-ordered microstructures they contain.
The team behind the current research, based at Cambridge’s Cavendish Laboratory, have been working on methods of artificially recreating this ‘structural colour’ for several years, but to date, it has been difficult to make these materials using techniques that are cheap enough to allow their widespread use.
In order to make the polymer opals, the team starts by growing vats of transparent plastic nano-spheres. Each tiny sphere is solid in the middle but sticky on the outside. The spheres are then dried out into a congealed mass. By bending sheets containing a sandwich of these spheres around successive rollers the balls are magically forced into perfectly arranged stacks, by which stage they have intense colour.
By changing the sizes of the starting nano-spheres, different colours (or wavelengths) of light are reflected. And since the material has a rubber-like consistency, when it is twisted and stretched, the spacing between the spheres changes, causing the material to change colour. When stretched, the material shifts into the blue range of the spectrum, and when compressed, the colour shifts towards red. When released, the material returns to its original colour. Such chameleon materials could find their way into colour-changing wallpapers, or building coatings that reflect away infrared thermal radiation.
A synthetic material which mimics the brightest and most vivid colours in nature, and changes colour when twisted or stretched, has been developed by researchers at the University of Cambridge, and could have important applications in the security, textile and sensing industries. The Polymer Opal films change to green and blue when stretched, and to red when compressed.
„Finding a way to coax objects a billionth of a metre across into perfect formation over kilometre scales is a miracle,” said Professor Jeremy Baumberg, the paper’s senior author. „But spheres are only the first step, as it should be applicable to more complex architectures on tiny scales.”
In order to make polymer opals in large quantities, the team first needed to understand their internal structure so that it could be replicated. Using a variety of techniques, including electron microscopy, x-ray scattering, rheology and optical spectroscopy, the researchers were able to see the three-dimensional position of the spheres within the material, measure how the spheres slide past each other, and how the colours change.
„It’s wonderful to finally understand the secrets of these attractive films,” said PhD student Qibin Zhao, the paper’s lead author.
Cambridge Enterprise, the University’s commercialisation arm which is helping to commercialise the material, has been contacted by more than 100 companies interested in using polymer opals, and a new spin-out Phomera Technologies has been founded. Phomera will look at ways of scaling up production of polymer opals, as well as selling the material to potential buyers. Possible applications the company is considering include coatings for buildings to reflect heat, smart clothing and footwear, or for banknote security and packaging applications.
Source: University of Cambridge

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