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NANO, TECHNOLOGY

Nanomaterials

DIAMONDOID: Like diamond; chemical structures or systems (especially nanomachines as envisioned by Eric K. Drexler) based on diamond derivatives or stiff carbon bonds.

HYPERDIAMONDS

We can make strong material like graphene, but we also make hardened material, even harder than diamond. Hyperdiamonds or Aggregated Diamond Nanorods are the hardest most dense and least compressible mayterial we know of. Diamonds are hard because of the molecular structure, each carbon atom forms 4 covalent bonds with the carbon atoms around it, which forms the hardest possible crystal structure. Hyperdiamond is an even more wear resistent type of diamond. This material is made up of many tiny interlocked diamond crystals rather than one single structure. They can be made in a lab by applying extreme heat and pressure to graphite. Diamonds are frequently used for industrial jobs like grinding and polishing because they’re so tough. But hyperdiamonds can be even useful than regular diamonds because they’re even more resistant to the temperature and pressure changes that can wear diamond down over time

 

CARBON NANOFIBERS

Carbon nanofibers or vapor grown carbon nanofibers are cylindric nanostructures with graphene layers arranged as stacked cones, cups or plates. We’ve figured out how to pull carbon nanofibers out of thin air. Carbon nanofibers, more precisely the production of carbon nanofiber, a material used in high end electronics like computers and smart phones. and can also be used to improve carbon composit materials in cars, airplanes, or spacecraft, where strong lightweigth material is a necessity. Normally the fabrication of this material is very expensive, prevented it from being used in common household aplications. Often cheaper materials such as plastics will suffice. But now scientists from geroge washington university have invented a low energy system that can be used to convert atmospheric carbon dioxide into valuable carbon nanofibers. It gets rid of useless carbon dioxzide from the atmosphere and makes a rare material. According to BBC news and laboratory tests, scientits put together a bath of molten salts and dropped some elctrodes in the baths. They then passed an electrical current through the salt and let it do its thing. Through a chemical reaction, black sooty residue began to form around the electrodes and the black stuff is carbon nanofibers. This system converts carbon dioxide from the atmosphere to this carbon residue at a rate of 10 grams per hour. And this is just a laboratory test, can you imagine what it could do once the system is scaled up for industrial use? The inventors want to scale it up to tap into a limitless supply of carbon dioxide, but perhaps one more lofty goal is to possibly help slow the global warming trend by pulling carbon dioxide out of the atmosphere. Carbon dioxide as we all know is a potent greenhouse gas, and our burning of fossil fuels is showing no signs of halting. It could be used as a ressource for infdustrial scale carbon nanofiber cfactories. But some scientists aren’t convinced they can be scaled up to the point where they can make a difference in the global co2 level. But the technology would produce an endless supply of carbon nanofibers whioch are biodegradable and can replace plastic. It could transform industrila applications for the material driving doewn the price and revolutioonizing certain products and technologies.

NANOTUBE FILM (STRONGER THAN KEVLAR)

IN BRIEF

Scientists have made a film from carbon nanotubes that has properties stronger and stretchier than that of kevlar or carbon fiber.

A FILM STRONGER THAN KEVLAR

Scientists have been experimenting with carbon nanotubes to create a host of things—everything from smaller resistors to smart skin. Not only is carbon nanotube exceptionally strong, it also possesses excellent conductive properties and flexibility.

A new study published in Nano Letters by researchers at East China University revealed that they have been able to create a film from carbon nanotubes that is five times stronger than prior films. Not only is it stronger than previously fabricated films, the new material is also stronger than films made from Kevlar or carbon fiber.

The research is groundbreaking, considering the difficulties of maintaining the mechanical properties of individual nanotubes once converted into films.

What is different in the new material is that the nanotubes are densely packed to each other and oriented parallel to each others, giving the films stronger strength. To accomplish this, the researchers did not try to align the nanotubes by spraying or filtering like previous studies did before. but instead developed their own, entirely new method.

By using a rotating drum, they were able to wind the carbon nanotubes around before flattening and cooling them into a two-layer film. They then compress the nanotubes further by using rollers. By varying the rotation of the drum faster, the scientists were able to find that faster winding would allow the nanotubes to align better.

 THE FUTURE IN FILM
Source:Nano Left
Source:Nano Letters

While the process may seem oddly simple, the strength of the resulting material is nothing to scoff at. The films produced had an average of 9.6 gigapascals. In contrast, films produced by prior research had only reached 2 GPa, while that of Kevlar and carbon fiber is around 3.7 and 7 GPa, respectively. Beyond that, the film is four times as pliable and stretchable as carbon fiber.

The research could prove useful as scientists try to develop nanotubes for use as electrodes for wearable devices and as artificial muscles.

The technique also results in pure carbon films as it does not require use of surfactants to produce allowing for simpler and more efficient production.

SYNTHETIC NANODIAMONDS

A team of researchers based at Yanshan University has produced a new synthetic diamond that’s remarkably robust, outperforming natural diamonds and other synthetic diamonds in both thermal stability and pressure tests. The results have been published in Nature.

Diamond is the hardest natural material known to man and consequently it is used in a wide variety of industrial settings such as aerospace engineering, mining and car manufacture. Its hardness and wear resistance makes it a particularly useful material for cutting tools but unfortunately poor stability at very high temperatures has restricted its applications in industry. Researchers are therefore turning to synthetic diamonds in order to overcome the limits of natural diamonds.

In nature, diamond occurs only as single crystals and while these materials are pretty hardy, they’re expensive and tend to wear unevenly. Synthetic diamonds, however, can either be prepared as single crystals or as a polycrystalline or nanocrystalline material. Polycrystalline diamond (PCD) is formed from tiny grains of diamond, as small as tens of nanometers in diameter, which have been fused together under high-pressure, high-temperature conditions. The smaller the grain, the harder the diamond.

These diamonds offer numerous benefits over natural diamonds given reduced costs, improved hardness and high wear resistance. However, industry is pushing these diamonds to the limits and there has been a need to develop even better diamonds.

In order to produce their super-hard diamond, the researchers subjected carbon nanoparticles that were layered like onions to high pressures and temperatures. The grains were arranged in pairs that were a mere 5 nanometers in size. The resulting “nanotwinned” diamond demonstrated remarkable thermal stability and hardness.

The team applied large pressures to the diamond and found that it was able to endure pressures of up to 200 gigapascals, which is around 1.9 million atmospheres. It would take only around half that pressure to shatter a natural diamond.

Next, they tested temperature resistance by investigating the highest temperature that could be tolerated before the diamond started to oxidize. They found the synthetic started to oxidize at temperatures between 980-1,056oC (1,796-1,932oF), which is around 200oC higher than that of natural diamond.

The researchers hope that this method could be adopted in industry as a way to produce novel carbon-based materials that are super-hard and exceptionally heat stable.

[via Nature and Live Science].

BORON BUCKYBALLS

Nanotechnology would not be where it is today without the 1985 discovery of buckminsterfullerene, also known as the “buckyball,” which is a stable arrangement of 60 carbon atoms. In recent years, chemists began to theorize that boron could be similarly arranged; a feat that was accomplished by an international team led Lai-Sheng Wang of Brown University. It is composed of 40 boron atoms, which Wang’s team named borospherene, and looks similar to a buckyball. The molecule was described in detail in the journal Nature Chemistry.

While the buckyball is composed of pentagons and hexagons patterned just like a soccer ball, borospherene’s cage-like structure is made up of heptagons, hexagons, and many smaller triangles. It’s structure is different than what has been predicted, as previous papers believed it would require 38 or 80 boron atoms to make a stable structure; not 40.

“This is the first time that a boron cage has been observed experimentally,” Wang said in a press release. “As a chemist, finding new molecules and structures is always exciting. The fact that boron has the capacity to form this kind of structure is very interesting.”

The discovery was made accidentally, as Wang’s lab had been trying to develop a boron version of graphene (a carbon monolayer arranged in a honeycomb pattern). They noticed that forty boron atoms became incredibly stable together, but needed to verify the shape. Over 10,000 computer simulations were created in order to find out how those 40 atoms could have come together, along with the electron bonding energy.

That bonding energy was then used to compare against the boron that had been created in the lab. Boron was transformed into a vapor by a laser, and the vapor was then frozen using helium, causing the vapor atoms to clump together. The clumps with 40 atoms were isolated and then subjected to another laser that disrupts the structure and helps to find the spectrum of the electron binding energy.

Combining the results of this method, known as photoelectron spectroscopy, and the computer simulations, Wang’s lab discovered that 40 boron atoms took on two shapes: one is borospherene and the other is a mostly-flat molecule.

“The experimental sighting of a binding spectrum that matched our models was of paramount importance,” Wang explained. “The experiment gives us these very specific signatures, and those signatures fit our models.”

Borospherene may bear a resemblance to buckyballs, but unlike the carbon-based molecule, the bonds within boron structure don’t allow it to function well on its own. The researchers are exploring its utility to be connected into a chain. The bonds are expected to work well with hydrogen and could possibly be useful for storing hydrogen.

NANOSILVER (MAKE GOLD WORTHLESS)

Alchemists dreamed of turning base metals to gold, but probably wouldn’t have been too sad at the modern achievement – turning silver to something with a striking likeness to the element below it on the periodic table. While it’s probably not time to sell gold stocks, the discovery may lead to silver’s substitution for some current uses of gold.

“When we first encountered the optical spectrum of the silver nanocluster, we thought that we may have inadvertently switched the chemical reagents for silver with gold, and ended up with gold nanoparticles instead,” Dr. Osman Bakr of King Abdullah University of Science and Technology, Saudi Arabia, told Phys.org. Bakr is the senior author of the paper in the Journal of the American Chemical Society.

Particles of a handful of atoms from a single element sometimes reveal properties very different from macroscopic collections of the same element. Solutions of gold nanoparticles vary in color – from deep red to bright pink to purple – depending on particle size.

The structure of silver nanoparticles are much less understood than their gold equivalents, but to the naked eye they do something similar; at certain sizes, silver nanoparticles look more like what you would expect of a solution of gold.

However, Bakr’s observation goes beyond mere looks. “This synthesized nanocluster is the only silver nanoparticle that has a virtually identical analogue in gold, in terms of number of metal atoms, ligand count, superatom electronic configuration, and atomic arrangement,” the paper reports.

The nanoparticle in question is [Ag25(SR)18], 25 silver atoms with 18 carbon-sulfur ligands (molecules that attach to the central complex of atoms).

Where silver nanoparticles with other numbers of atoms structure differently from gold, the behavior of [Ag25(SR)18] is so similar in structure to its well-studied gold equivalent that the authors argue it “offers the first model nanoparticle platform to investigate the centuries-old problem of understanding the fundamental differences between silver and gold in terms of nobility, catalytic activity, and optical property.” The question is important because silver is so toxic, it is used for antibacterial coatings; whereas gold is so unreactive, it is biologically safe.

Bakr told Phys.org that the similarities in properties arise from the 25 atoms behaving like a single “superatom” whose structure determines interactions with the outside world. “The size scale of nanoparticles lies in between atoms/molecules and bulk material, where the absolute rule of neither quantum nor classical physics is observed,” he said.

The authors probed the structure of the two nanoparticles with X-ray diffraction, finding that each have a single atom at the center of a 12-pointed icosahedron, nine “atoms occupy the nine triangular face centers of the core, whereas the remaining three can be found facing away from triangular face centers,” the paper notes. The last three represent the only difference from the structure of Au25, where 12 gold atoms occupy triangular faces, explaining the strong similarity in properties.

Bakr suggested that just as silver can be made to mimic gold, the reverse may also be achievable, although likely less commercially attractive.

American politics once turned on the demand to substitute silver for the “cross of gold,” but no one guessed that at the smallest scale, the difference disappears.

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