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SPONSOR: Gratomic Inc. (TSX-V: GRAT) Advanced materials company focused on mine to market commercialization of graphite products, most notably high value graphene based components for a range of mass market products. Collaborating with Perpetuus, Gratomic will use Aukam graphite to manufacture graphene products for commercialization on an industrial scale. For More Info Click Here

In the weeks since the Physics World team kicked off the new year by testing a pair of graphene headphones, we’ve received a steady stream of comments about our review and a related segment on our weekly podcast. A few people have asked our opinion of other graphene headphones, and one man went so far as to question whether the “graphene” label he found on an inexpensive pair of headphones was anything more than “misleading click-bait”.

I can’t judge any product I haven’t tried, and I also can’t judge a product’s graphene content without taking it apart and getting experts to analyse it. However, with those two caveats firmly in place, here are two facts to consider should you happen to be in the market for graphene headphones (and, by extension, graphene anything).

First, a lot of things contribute to how a pair of headphones will sound. The physical composition of the headphone drivers (graphene, PET, cellulose, or whatever) is only one factor. Others include the method by which those drivers create sound (this blog post explains a few of the possibilities, and their trade-offs); the quality of the other electronics; and simple things like how well the headphones fit over/in your ears. Some of these things are more expensive to optimize than others. The graphene headphones I tested are a high-end product with, it appears, a high-end price, so I suspect they are pretty good at the non-graphene-related aspects of headphone design – and that much of their cost comes from that, not from the graphene.

Second, graphene exists in many forms, with many price points. A lot of physicists are interested in ultra-pure, single-layer graphene, which has amazing electronic properties. This “physicists’ graphene” is difficult (and expensive) to make in macroscopic quantities. However, others are more interested in graphene’s mechanical properties, such as strength and rigidity. To get these properties, you don’t need ultra-pure single-layer graphene. You can get by with a cheaper type, which for argument’s sake I will term “materials scientists’ graphene” (this is an oversimplification, but it conveys the right feel). The proprietary graphene-based material in the headphones I tested was most likely in this category.

But even this type of graphene is expensive relative to a third type of graphene, which is cheap enough to be added in bulk to substances like paint or resin to improve their heat transport and/or electrical conductivity. As I understand it, this “engineers’ graphene” functions like a superior version of graphite, and manufacturers are selling it by the kilo (and maybe, soon, by the tonne).

I’m not trying to start a three-way brawl between physicists, materials scientists and engineers about which type of graphene is better. They all have their uses, and they all qualify as graphene. But here’s the problem: a product can advertise itself, accurately, as containing graphene even if the graphene it contains is not of a type or quantity that’s going to make a difference to its performance. What’s more, if an unscrupulous manufacturer wants to put graphite in its product and call it “graphene”, it’s hard for ordinary consumers to know the difference. To the naked eye, graphene and graphite both look like gritty black powders. You need more sophisticated testing equipment to distinguish between them, and between the various grades of graphene.

Certification is a huge issue for the graphene industry, and a lot of people are working on it. However, until there’s a strong framework for regulation, the next best thing is probably to look for independent endorsements by people and organizations who know what they’re talking about. The headphones I tried were endorsed by the co-discoverer of graphene, Kostya Novoselov, as making good use of the material. Since then, I’ve learned of a different make of graphene headphones that has been endorsed by an industry body called the Graphene Council. However, until someone gives Physics World its own product-testing lab and qualified technicians to run it, that’s about all I can say – except to add that there are some graphene products I definitely won’t be testing with my colleagues.

SOURCE:https://physicsworld.com/a/graphene-for-physicists-materials-scientists-and-engineers/

SPONSOR: Gratomic Inc. (TSX-V: GRAT) Advanced materials company focused on mine to market commercialization of graphite products, most notably high value graphene based components for a range of mass market products. Collaborating with Perpetuus, Gratomic will use Aukam graphite to manufacture graphene products for commercialization on an industrial scale. For More Info Click Here

A new technique to make ultra-flat, wrinkle-free films of graphene could pave the way for a host of applications, including graphene-based flexible electronics and high-frequency transistors. The technique works by introducing protons into the film as graphene is synthesized using chemical vapour deposition (CVD), and its inventors say that it might be extended to other two-dimensional materials such hexagonal boron nitride (h-BN) and the transition-metal dichalcogenides (TMDCs). It could also aid the development of hydrogen storage devices made from layered 2D structures.

Graphene – a 2D honeycomb of carbon atoms just one atom thick – boasts several unique electronic properties. In contrast to conventional semiconductors, which have an energy gap between the electron valence and conduction bands, graphene is a “zero-gap” semiconductor. This means its electron valence and conduction bands just touch each other. At the point of contact, the electrons move at near-ballistic speeds, and their behaviour is governed by the Dirac equation for relativistic electrons – hence the name “Dirac point” for this section of graphene’s band structure.

Linear defects

So far, this electronic behaviour has only been observed in small flakes of graphene that have been shaved off, or exfoliated, from samples of bulk graphite. These flakes are not big enough to be practical for electronic circuits, and although larger, wafer-sized graphene films can easily be produced via CVD, their electronic performance is not as good. This is because CVD-grown graphene, unlike the exfoliated type, contains grain boundaries, atomic vacancies, impurities and wrinkles. These defects act as centres off which electrons can scatter as they travel, thus degrading the material’s electronic properties.

CVD-produced graphene is prone to wrinkling because the graphene must adhere to the surface of a substrate as it grows. If the thermal expansion coefficient of the substrate does not match that of the graphene itself, a change in temperature can lead to linear defects – wrinkles – forming as the ensemble strives to release compressive strain.

Researchers have attempted to reduce wrinkling by performing CVD at low temperatures, using substrates with a similar thermal coefficient to that of graphene, and developing single-crystalline substrates. A team of researchers led by Libo Gao at China’s Nanjing University has now shown that reducing the interaction between graphene and its substrate might be a good, alternative, strategy.

Intercalating hydrogen molecules

The Nanjing team began by introducing a plasma of protons – hydrogen ions – into the graphene’s growth chamber. During the CVD process, some of this hydrogen became intercalated between the graphene and its substrate, causing the two materials to decouple.

Gao and colleagues found that some of the wrinkles disappeared entirely from the graphene thanks to this proton penetration. They believe this is due to decreased van der Waals interactions between the carbon sheet and the substrate, as well as – possibly – an increase in the substrate’s distance from the growth surface thanks to the intercalation process.

High-quality bilayer graphene goes large

The researchers also found that the electronic band structure of their graphene films shows a V-shaped “Dirac cone” (representing the density of states around the Dirac point) similar to the one observed in exfoliated graphene. They argue that this proves the proton-assisted CVD-grown graphene is indeed decoupled from its substrate.

The technique, which is detailed in Nature, could be extended to grow ultra-flat versions of other 2D materials, such as h-BN and the TMDCs, Gao says. It might also make it possible to develop hydrogen storage devices made from these layered materials.

“The physical and electronic properties of our ultra-flat graphene films are homogenous on the large scale, which means they might now be used in higher-performance electronic and photoelectronic devices,” he tells Physics World.

Source:https://physicsworld.com/a/ultra-flat-graphene-goes-wrinkle-free/

SPONSOR: Gratomic Inc. (TSX-V: GRAT) Advanced materials company focused on mine to market commercialization of graphite products, most notably high value graphene based components for a range of mass market products. Collaborating with Perpetuus, Gratomic will use Aukam graphite to manufacture graphene products for commercialization on an industrial scale. For More Info Click Here

• “Experts say we are approaching a tipping point for graphene commercialisation”

Andy Burnham, Mayor for Greater Manchester, made a fact-finding tour of facilities that are pioneering graphene innovation at The University of Manchester.

The Mayor toured the Graphene Engineering Innovation Centre (GEIC) which is an industry-facing facility specialising in the rapid development and scale up of graphene and other 2D materials applications.

As well as state-of-the art labs and equipment, the Mayor was also shown examples of commercialisation – including the world’s first-ever sports shoes to use graphene which has been produced by specialist sports footwear company inov-8 who are based in the North.

Andy Burnham – a running enthusiast who has previously participated in a number of marathons – has promised to put a pair of graphene trainers to the test and feedback his own experiences to researchers based at The University of Manchester. “Manchester is the home of graphene – and when you see the brilliant work and the products now being developed with the help of the Graphene@Manchester team it’s clear why this city-region maintains global leadership in research and innovation around this fantastic advanced material.” Andy Burnham, Greater Manchester Mayor

By collaborating with graphene experts in Manchester, inov-8 has been able to develop a graphene-enhanced rubber which they now use for outsoles in a new range of running and fitness shoes. In testing, the groundbreaking G-SERIES shoes have outlasted 1,000 miles and are scientifically proven to be 50% stronger, 50% more elastic and 50% harder wearing.

“Manchester is the home of graphene – and when you see the brilliant work and the products now being developed with the help of the Graphene@Manchester team it’s clear why this city-region maintains global leadership in research and innovation around this fantastic advanced material,” said Andy Burnham.

“I have been very impressed with the exciting model of innovation the University has pioneered in our city-region, with the Graphene Engineering Innovation Centre playing a vital role by working with its many business partners to take breakthrough science from the lab and apply it to real world challenges.

“And thanks to world firsts, like the graphene running shoe, the application of graphene is now gaining real pace. In fact, the experts say we are approaching a tipping point for graphene commercialisation – and this is being led right here in Greater Manchester.”

Source: https://www.manchester.ac.uk/discover/news/mayor-praises-manchester-model-of-innovation-as-graphene-applications-gain-real-pace/