17 OCTOBER 2013
CARBON'S NEW CHAMPION
Rice University theorists calculate atom-thick carbyne chains may be strongest material ever.
Carbyne will be the strongest of a new class of microscopic materials if and when anyone can make it in bulk.
If they do, they'll find carbyne nanorods or nanoropes have a host of remarkable and useful properties, as described in a new paper by Rice University theoretical physicist Boris Yakobson and his group. The paper appears this week in the American Chemical Society journal ACS Nano.
Carbyne is a chain of carbon atoms held together by either double or alternating single and triple atomic bonds. That makes it a true one-dimensional material, unlike atom-thin sheets of graphene that have a top and a bottom or hollow nanotubes that have an inside and outside.
According to the portrait drawn from calculations by Yakobson and his group:
* Carbyne's tensile strength – the ability to withstand stretching – surpasses "that of any other known material" and is double that of graphene. (Scientists had already calculated it would take an elephant on a pencil to break through a sheet of graphene.)
* It has twice the tensile stiffness of graphene and carbon nanotubes and nearly three times that of diamond.
* Stretching carbyne as little as 10 percent alters its electronic band gap significantly.
* If outfitted with molecular handles at the ends, it can also be twisted to alter its band gap. With a 90-degree end-to-end rotation, it becomes a magnetic semiconductor.
* Carbyne chains can take on side molecules that may make the chains suitable for energy storage.
* The material is stable at room temperature, largely resisting crosslinks with nearby chains.
That's a remarkable set of qualities for a simple string of carbon atoms, Yakobson said.
"You could look at it as an ultimately thin graphene ribbon, reduced to just one atom, or an ultimately thin nanotube," he said. It could be useful for nanomechanical systems, in spintronic devices, as sensors, as strong and light materials for mechanical applications or for energy storage.
"Regardless of the applications," he said, "academically, it's very exciting to know the strongest possible assembly of atoms."
Based on the calculations, he said carbyne might be the highest energy state for stable carbon. "People usually look for what is called the 'ground state,' the lowest possible energy configuration for atoms," Yakobson said. "For carbon, that would be graphite, followed by diamond, then nanotubes, then fullerenes. But nobody asks about the highest energy configuration. We think this may be it, a stable structure at the highest energy possible."
Theories about carbyne first appeared in the 19th century, and an approximation of the material was first synthesized in the USSR in 1960. Carbyne has since been seen in compressed graphite, has been detected in interstellar dust and has been created in small quantities by experimentalists.
"I have always been interested in the stability of ultimately thin wires of anything and how thin a rod you could make from a given chemical," Yakobson said. "We had a paper 10 years ago about silicon in which we explored what happens to silicon nanowire as it gets thinner. To me, this was just a part of the same question."
The Rice researchers, led by Rice graduate student Mingjie Liu and postdoctoral researcher Vasilii Artyukhov, were aware of a number of papers that described one property or another of carbyne. They set out to detail carbyne with computer models using first-principle rules to determine the energetic interactions of atoms, Artyukhov said.
"Our intention was to put it all together, to construct a complete mechanical picture of carbyne as a material," Artyukhov said. "The fact that it has been observed tells us it's stable under tension, at least, because otherwise it would just fall apart."
Yakobson said the researchers were surprised to find that the band gap in carbyne was so sensitive to twisting. "It will be useful as a sensor for torsion or magnetic fields, if you can find a way to attach it to something that will make it twist," he said. "We didn't look for this, specifically; it came up as a side product."
"That's the good thing about studying things carefully," Artyukhov said.
Another finding of great interest was the energy barrier that keeps atoms on adjacent carbyne chains from collapsing into each other. "When you're talking about theoretical material, you always need to be careful to see if it will react with itself," Artyukhov said. "This has never really been investigated for carbyne."
The literature seemed to indicate carbyne "was not stable and would form graphite or soot," he said.
Instead, the researchers found carbon atoms on separate strings might overcome the barrier in one spot, but the rods' stiffness would prevent them from coming together in a second location, at least at room temperature. "They would look like butterfly wings," Artyukhov said.
"Bundles might stick to each other, but they wouldn't collapse completely," Yakobson added. "That could make for a highly porous, random net that may be good for adsorption." Artyukhov said the nominal specific area of carbyne is about five times that of graphene.
When the team's paper became available this summer on arXiv, the scientific press and even some of the popular press were so excited over the calculations that they picked up on the paper and its implications before the team submitted it for peer review. Now that the complete paper is ready for public consumption, the researchers said they'll carry their investigation in new directions.
They're taking a more rigorous look at the conductivity of carbyne and are thinking about other elements as well. "We've talked about going through different elements in the periodic table to see if some of them can form one-dimensional chains," Yakobson said.
Rice graduate student Fangbo Xu and former postdoctoral researcher Hoonkyung Lee, now a professor at Konkuk University in South Korea, are co-authors of the paper. Yakobson is Rice's Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science, a professor of chemistry and a member of the Richard E. Smalley Institute for Nanoscale Science and Technology.
The Air Force Office of Scientific Research and the Welch Foundation supported the research. Calculations were performed on the National Science Foundation-supported DaVinCI supercomputer, administered by Rice's Ken Kennedy Institute for Information Technology.
17 OCTOBER 2013
GRAPHENE 2014 RAISING GREAT INTEREST
The largest European event on Graphene (Graphene conference series), Graphene 2014, is rapidly growing and raising great interest from the Graphene Community Worldwide.
Currently the event unveils 30 invited and keynote speakers from top level institutions. The plenary session will gather internationally renowned speakers covering most fundamental issues in graphene and two-dimensional materials, as well as challenges in large scale synthesis and applications (Samsung, Nokia, Airbus…).
Extensive thematic workshops in parallel are planned (Applications of Graphene-based Materials, Materials & Devices Characterization, Theory & Simulation, Worldwide Graphene Initiatives, Funding and Priorities) and a strong focus in current and future applications of graphene with the GRAPHENE FLAGSHIP industrial workshop "Composites".
The Graphene 2014 Conference will feature for the first time an exhibition of Worldwide Graphene Research Centers, apart from all the companies that usually attend and will certainly boost networking between research institutes, investors, engineers and industrials. Graphene research centers, investment companies, graphene producers, publishers are among the 20 exhibitors that already confirmed attendance.
The abstract submission will open on the 4th week of October and will remain until February 03, 2014.
Opportunities for PhD students will be available on dedicated sessions and grants will also be offered.
Graphene 2014 will be held in Toulouse (France) between the 6 and the 9 of May 2014 at the Centre de Congrès Pierre Baudis.
Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Phantoms Foundation www.phantomsnet.net
Université Catholique de Louvain (UCL)
Université de Bordeaux
Université de Montpellier 2
8 OCTOBER 2013
EUROPE LAUNCHES THE 1 BILLION EURO GRAPHENE FLAGSHIP THIS WEEK
After years of preparations it is time for Europe to launch The Graphene Flagship – a 10-year, 1,000 million euro research and innovation initiative on graphene and related layered materials.
Graphene – a single layer of carbon atoms – may be the most amazing and versatile substance available to mankind. Being the world's strongest material, harder than diamond, yet lightweight and flexible, graphene enables electrons to flow much faster than silicon. It is also a transparent conductor, combining electrical and optical functionalities in an exceptional way. This unique combination of superior properties makes it a credible starting point for new disruptive technologies in a wide range of fields.
Now, on October 10-11, graphene researchers from all over Europe – from 74 research partners in 17 countries – will gather in Gothenburg, Sweden, for kick-off. Their mission is to take the supermaterial graphene and related ultra-thin layered materials from academic laboratories to society, revolutionize multiple industries and create economic growth and new jobs in Europe.
Being a FET (Future & Emerging Technologies) Flagship by the European Commission, The Graphene Flagship is one of Europe's two most ambitious science projects ever.
7 OCTOBER 2013
GRAPHENE COULD MAKE DATA CENTERS AND SUPERCOMPUTERS MORE EFFICIENT
By Mike Orcutt
New research suggests graphene could enable highly efficient optical communication in chips for data centers and supercomputers.
Computer chips that use light, instead of electrons, to move data between electronic components and to other chips could be essential for more efficient supercomputers and data centers. Several industrial research labs are working toward such optical interconnects that rely on germanium to turn light into ones and zeros. But recent research suggests that graphene devices could be far better and cheaper.
An optical interconnect consists of a modulator that converts electrical signals into optical ones, and a photodetector, which does the reverse. Current iterations feature modulators made of silicon and photodetectors made of germanium. Intel recently announced plans to use such technology and begin manufacturing a product it calls "silicon photonics," for use in data centers (see "Intel's Laser Chips Could Make Data Centers Run Better").
But graphene photodetectors have a good chance to equal or surpass the performance of germanium ones in several important aspects within a few years, says Dirk Englund, a professor of electrical engineering and computer science at MIT. Although graphene devices are still about an order of magnitude behind germanium in terms of capacity to generate current in response to the absorption of light, they have improved immensely in this area in just a few years.
Graphene has a number of potential advantages over germanium, says Englund. Because of its exceptional electronic properties, devices made of the material can work at very high frequencies, and could in principle handle more information per second. Also, graphene can absorb a broader range of wavelengths than germanium can. That property could be exploited to transmit more data streams simultaneously in the same beam of light. Further, unlike germanium detectors, graphene photodetectors work "quite well" without applied voltage, which could reduce the energy needed to transmit data, says Englund. Finally, he says, graphene detectors would in principle require a simpler and potentially less expensive process to integrate them on a silicon chip.
But graphene as a photodetector material has at least one big problem: it does not strongly absorb light. To address this issue, three groups—one led by Englund, one led by Thomas Mueller, a professor at Vienna Institute of Technology's Institute of Photonics, and a team at the Chinese University of Hong Kong—have separately designed on-chip detectors consisting of a graphene sheet paired with a silicon waveguide, a component that confines and routes light and maximizes the interaction.
The first graphene-based modulator was demonstrated in 2011. So this recent work suggests it might be possible to build an optical interconnect entirely out of graphene.
An important caveat to the new demonstrations is that, in each case, graphene was transferred to the silicon substrate by mechanical processes that are not conducive to large-scale manufacturing. There has been recent progress toward developing a large-scale process for growing graphene on desired substrates, but that option is not yet viable.
Further, graphene photodetectors are very far behind germanium ones in terms of technology development, cautions Solomon Assefa, a research scientist at IBM's T.J. Watson Research Center. With graphene, he says, "there's still a lot to be done. It could potentially be cost-effective, but we still have to find out."
1 OCTOBER 2013
GRAPHENE MOVES BEYOND THE HYPE AT THE GRAPHENE LIVE! USA EVENT
The graphene industry is moving beyond the hype and is focusing on realistic low hanging fruits. The production methods are fast improving, making volume production at competitive prices possible in the medium term. Most suppliers are fast moving up the value chain to focus on higher value added products such as master-batches or inks. Significant money continues to be poured into R&D, company formation and scale-up across the world. This industry is changing and growing up fast.
The Graphene LIVE! USA event has lined up top-class speakers for its business-orientated conference and tradeshow on graphene. You will hear from leading academics, producers and end users. The discussion will focus on latest application ideas and roadmaps, new and improved production methods, and the latest commercialisation progress and challenges across a variety of sectors including energy storage, transparent conductive films and printed electronics.
IDTechEx also organises parallel conferences on transparent conductive films, supercapacitors and printed electronics, all of which are primary target applications for graphene. This ensures that our attendees learn the latest in terms of needs and commercialisation progress from relevant end user groups, while also being able to simultaneously assess technologies competing against graphene.
This is the biggest question facing graphene- what are the killer applications? At Graphene LIVE! USA, graphene companies will announce and discuss their latest application ideas for graphene. Tata Steel, Vorbeck Materials, Xolve and Graphene Technologies will specifically focus on this.
The energy storage sector is a promising target market for graphene. This market includes both supercapacitor and Li-ion battery electrodes. Graphene has potential to deliver value in the supercapacitor sector given that these devices demand high surface area between electrodes and the electrolytes. The supercapacitors are also a fast-growing sector which is projected to grow to $11 billion in 2023.
At Graphene LIVE! USA, you will hear first-hand from Cabot Corporation, which is commercialising graphene-based additives aimed at Li-ion battery electrodes. You will also hear from Graphenea, Graphene Devices and Graphene Frontiers, which are also focusing on supercapacitors.
Leading supercapacitor companies such as Maxwell Technologies and Cap-XX, as well as IDTechEx analysts will outline the commercial opportunities and challenges facing the supercapacitor industry as a whole.
Volume production cost of graphene is still too high for many applications. This is particularly relevant because the go-to-market strategy in many sectors is replacing an existing material. The production method also has a direct bearing on the material properties of graphene and therefore the potential end use applications.
At Graphene LIVE! USA, you will hear about latest developments on production techniques. PPG Industries, Grafoid, Incubation Alliance, Durham Graphene Science, 2D-Tech and Angstron Materials will also discuss their production methods, which cover a broad range of techniques including exfoliation, substrate-less CVD, oxidisation-reduction, plasma, etc
Transparent conductive films
Transparent conductive film and glass markets are booming and also being fast transformed. The market will grow to $6.3 billion in 2024. Crucially, the needs of the industry are fast changing with the advent of large-area, current-driven and/or flexible devices. This opens the space for a range of alternatives to the incumbent ITO. The emerging contenders are silver nanowires, metal mesh, carbon nanotubes, PEDOT and graphene.
At Graphene Live!, you will hear from leading companies that target the transparent conductive film market such as Bluestone Global Tech. Crucially, you will also hear from leading players working on rival materials such as carbon nanotubes, silver nanowires, and PEDOT. Some notable speakers here include Canatu, Brewer Science, Agfa, Carestream Advanced Materials, Rolith, Blue Nano, Cambrios, Uni-Pixel, Synaptics, etc. This is set to give you an in-depth yet comprehensive view of the changing technology and market landscape for transparent conductive films.
Graphene can be formulated into printable conductive (and also in some instances transparent) inks. This is one of the lowest hanging fruits for graphene suppliers as both the technology and market barriers are low compared to many other target markets. At Graphene LIVE! USA, you will hear from XG Sciences, University of Cambridge, and Cambridge Graphene Platform on graphene inks.
It is crucial to also note that all key players across the value chain of printed electronics will speak and/or exhibit at our co-located conference and exhibition. This will give you the chance to hear the latest from potential end user, and also technological rivals to graphene inks. Some notable companies in this respect include NanoIntegris, Okayama University, Toyobo, and Intrinsiq Materials,
Novel types of graphene and other 2D materials
2D materials are extending beyond just graphene to cover a wealth of novel materials with promising properties. At Graphene LIVE! USA, you will hear from Momentive Performance Materials, AZEM, Graphene Laboratories and Cambridge Platform about other 2D or high-aspect ratio nano materials.
IDTechEx has also worked hard to create a vibrant tradeshow. We have 150 exhibiting companies across co-located event, 15 of which are graphene supplies and many others are relevant end users and/or technological competitors (e.g., silver nanowire or carbon nanotube producers). This therefore creates a fantastic opportunity to network and understand the latest commercial progress.