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From: DanD9/12/2011 12:47:57 PM
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Graphene may open the gate to future terahertz technologiesSeptember 12th, 2011 in Nanotechnology / Nanophysics


Nestled between radio waves and infrared light is the terahertz (THz) portion of the electromagnetic spectrum. By adding a nanoscale bit of graphene, researchers have found a better way to tune radiation for a THz transmitter.

Researchers from the University of Notre Dame in Indiana have harnessed another one of graphene's remarkable properties to better control a relatively untamed portion of the electromagnetic spectrum: the terahertz band.

Terahertz radiation offers tantalizing new opportunities in communications, medical imaging, and chemical detection. Straddling the transition between the highest energy radio waves and the lowest energy infrared light, terahertz waves are notoriously difficult to produce, detect, and modulate. Modulation, or varying the height of the terahertz waves, is particularly important because a modulated signal can carry information and is more versatile for applications such as chemical and biological sensing. Some of today's most promising terahertz technologies are based on small semiconductor transistor-like structures that are able to modulate a terahertz signal at room temperature, which is a significant advantage over earlier modulators that could only operate at extremely cold temperatures.

Unfortunately, these transistor-like devices rely on a thin layer of metal called a "metal gate" to tune the terahertz signal. This metal gate significantly reduces the signal strength and limits how much the signal can be modulated to a lackluster 30 percent. As reported in the AIP's journal Applied Physics Letters, by replacing the metal gate with a single layer of graphene, the researchers have predicted that the modulation range can be significantly expanded to be in excess of 90 percent. This modulation is controlled by applying a voltage between the graphene and semiconductor. Unlike the metal gate modulator, the graphene design barely diminished the output power of the terahertz energy. Made up of a one-atom-thick sheet of carbon atoms, graphene boasts a host of amazing properties: it's remarkably strong, a superb thermal insulator, a conductor of electricity, and now a better means to modulate terahertz radiation.

More information: “Unique prospects for graphene-based terahertz modulators” by Berardi Sensale-Rodriguez et al. is accepted for publication in Applied Physics Letters.


Provided by American Institute of Physics

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From: DanD9/20/2011 3:26:56 PM
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Graphene can be strengthened by folding
September 20th, 2011 in Nanotechnology / Nanomaterials


(PhysOrg.com) -- With a strength 200 times greater than that of steel, graphene is the strongest known material to exist. But now scientists have found that folding graphene nanoribbons into structures they call “grafold” can enable it to bear even greater compressive loads.

The researchers, Yongping Zheng and Zhigao Huang of Fujian Normal University in China; Ning Wei and Zheyong Fan of Xiamen University in China; and Lanqing Xu of both universities, have published their study in a recent issue of Nanotechnology.

“The results of this work provide a new route for tailoring the properties of graphene-based nanomaterials,” Zheng told PhysOrg.com. “Currently, many researchers and engineers are concerned with doping, alchemy, etc. We have demonstrated here that structure re-construction could also lead to interesting results.”

In their study, the researchers used molecular dynamics simulations to investigate grafold. They compared graphene with grafold in two areas: tension (the force that pulls the material apart) and compression (the force that pushes the material together). The ability to be both elongated and squeezed without damage is very helpful for engineering applications. However, as the researchers explain, graphene only has a high tensile strength; because of its two-dimensional nature, it is “soft” under compression and can’t be squeezed.

In contrast, the researchers’ simulations showed that grafold is “harder” than graphene and can withstand much larger amounts of compression (10-25 GPa depending on the structure of grafold compared with less than 2 GPa for graphene). While its compressive strength is significantly higher than that of graphene, grafold’s tensile strength approaches that of graphene. The Young’s modulus (a measure of elasticity) and fracture strain of grafold are a little lower than those of graphene. The scientists noted that several other materials can withstand greater compression than grafold, including carbon nanotubes, which can be both elongated and squeezed like grafold.

“As is well known, graphene can’t withstand any compression,” Zheng said. “Via folding, graphene transforms into grafold and can be compressed to a certain amount. Even when highly compressed, it won’t break down, just be squeezed into a shorter folded belt. Furthermore, the deformation is elastic. As we know, if the strength exceeds carbon nanotubes’ breaking point, it will crash and never return to its original form.”

Among grafold’s advantages is that folding a graphene nanoribbon to create grafold will be much easier than rolling it up to create a carbon nanotube. Plus, grafold’s mechanical properties can be tuned by the modifying the folding design, such as changing the size, shape, and number of folds.
Overall, the results of the simulations provide a new route for tailoring the properties of graphene-based nanomaterials, which could lead to advanced mechanical applications. The researchers hope to experimentally fabricate grafold in the near future.

“There could be versatile applications,” Zheng said. “Say, one could utilize the elastic and low-to-mid stiffness of grafold in applications where a large damping is required.”

More information: Yongping Zheng, et al. “Mechanical properties of grafold: a demonstration of strengthened graphene.” Nanotechnology 22 (2011) 405701 (9pp). DOI:10.1088/0957-4484/22/40/405701
Copyright 2011 PhysOrg.com.

"Graphene can be strengthened by folding." September 20th, 2011. physorg.com

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From: DanD9/20/2011 3:32:06 PM
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Super tiny technology could power superfast airplanes

Posted July 17, 2009; 12:26 p.m. share | e-mail | printby Chris EmerySupersonic aircraft may get a boost in speed from the tiniest of manmade particles.

An interdisciplinary team of scientists led by Princeton engineers has been awarded a $3 million grant to study how fuel additives made of tiny particles known as nanocatalysts can help supersonic jets fly faster and make diesel engines cleaner and more efficient.

princeton.edu

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From: swivel-eyed loon9/23/2011 12:58:04 PM
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Graphene Could Replace Silicon, But Chip Firms Lag

Investors Business Daily, September 21, 2011

Observers hail graphene as a new wonder material that could replace silicon in chips and change electronics and other sectors.

Just one problem: The semiconductor equipment industry has yet to jump on the graphene bandwagon by developing gear and manufacturing tools to handle the material.

But graphene research is booming at U.S. universities. R&D labs are developing uses for graphene in communications devices, solar cells, flexible touch-screens, aircraft materials, gas tanks and more. The labs, out of necessity, use their own in-house techniques for graphene-related research.

The chip equipment industry must play a bigger role, says Michael Fritze, director of the disruptive technologies program at the Information Sciences Institute, University of Southern California.

"A step in the right direction would be to have some high-quality commercial tools available," he said.

Many obstacles exist to commercializing products based on graphene, a one-atom-thick sheet of carbon that's organized like chicken wire in molecular form. Graphene, a form of graphite, wasn't discovered until 2004. The material, though, got a big boost in October. That's when Andre Geim and Konstantin Novoselov, two University of Manchester, England, scientists, were awarded the Nobel Prize in physics for their pioneering research on graphene.

The material is said to be 100 times stronger than steel and conducts electricity as well as copper. Thus it's touted as a replacement for silicon in computer chips. Researchers plan to use it also to strengthen plastics, coatings and conductive inks such as those that provide copper etchings on chips.

Small CVD Equipment ( CVV) is among leaders in graphene, looking to sell it to universities and industrial researchers. The Ronkonkoma, N.Y.-based company had sales of just $7.5 million last quarter, but its early work in graphene has helped the stock.

Germany's Aixtron ( AIXG) also is an early leader in graphene.

But Applied Materials ( AMAT) and other leading makers of manufacturing gear used to make chips, flat-panel displays and solar panels have stayed on the sidelines. None has yet disclosed they are actively developing gear that would be used to put ultrathin graphene layers on copper, plastic or glass substrates.

Chip gear companies, though, have shown interest.

In May, USC's Fritze headed a graphene conference that brought together university researchers and companies. He says gear makers such as Applied Materials seemed to be in serious talks with other attendees.

Some Production Under Way

Graphene is produced in very small amounts by U.S. companies such as Vorbeck Materials, XG Sciences and Angstron Materials, says a Lux Research report. Some universities bake their own graphene in high-temperature ovens. The big challenge for researchers is developing manufacturing tools, says Lux Research analyst Jonathan Melnick.

"Research is still at a basic, fundamental level of getting graphene into products," Melnick said. "They're trying to figure out cheaper, more efficient ways to produce graphene. It's a challenge getting (manufacturing) scale up and costs down."

Samsung and Texas Instruments ( TXN) are among chipmakers with graphene-related R&D under way. Samsung last year licensed graphene patents from Unidym, a unit of Arrowhead Research ( ARWR).

"Many university research labs are looking at graphene. IBM ( IBM) has done a lot of work. Intel ( INTC) has R&D," said Dean Freeman, an analyst at market research firm Gartner. "But it's still sandbox, early-stage type work. There's nothing close to volume production.

"If graphene moves closer to reality, then you will see (big) equipment companies looking at how to address the market."

CVD Equipment last year teamed with startup Graphene Laboratories to sell graphene substrate services to universities and industrial labs. CVD hasn't disclosed its graphene sales, though they likely remain quite small.

The big question remains whether graphene is the real thing, not another overhyped technology such as carbon nanotubes. Scientists say it'll be at least five to 10 years before applications of graphene technology come to market.

USC's Fritze, however, says thin films of graphene have been successfully put on wafers, opening the door to electronics applications. There are hurdles, though. While graphene conducts electricity, researchers have yet to develop on/off switches in circuitry as in silicon-based devices.

Freeman says graphene-based devices will emerge first for communications devices that don't require digital switches, such as high-frequency microwave transmitters used in satellites.

Fritze says graphene sheets have been put on bigger-size substrates for various purposes. He says "smart windows" is one area of research, especially in South Korea. Smart glass controls how much light and heat passes through.

How soon graphene-based products emerge "depends on how seriously companies invest in it and what the potential looks like after they kick the tires," Fritze said.

Many startups have sprouted, some spun out of university labs. In June, Korean steel firm Posco acquired a 20% stake in XG Sciences, a spin-off of Michigan State University. Texas-based Graphene Energy is working on energy storage.

Graphene is a two-dimensional form of graphite, basically pencil lead. Companies that sell graphite are moving into graphene.

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From: DanD9/23/2011 3:29:43 PM
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MIT Setting Up Industrial-Scale Graphene Printing Press

CARL FRANZEN SEPTEMBER 23, 2011, 10:30 AM 681 1


Researchers at the Masscusetts Institute of Technology are working on creating an industrial-scale printing press for graphene, a miraculous, Nobel Prize-winning, one atom-thick carbon nano-material, for use in next generation electronic devices.

...

idealab.talkingpointsmemo.com

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From: DanD9/23/2011 4:15:35 PM
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Is graphene the best quantum resistance standard?
September 19, 2011

Graphene has the potential to surpass conventional materials in many applications including quantum resistance metrology. New research from NPL's Quantum Detection Group presents the most precise measurements of the quantum Hall effect ever made, using the two-dimensional material graphene.

...

physorg.com

[Video Included]

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From: swivel-eyed loon9/23/2011 4:31:49 PM
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Graphene: How beautiful is this?

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From: DanD9/26/2011 3:15:55 PM
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Graphene walls could make powerful electronics
Rice, Hong Kong Polytechnic physicists calculate 100 trillion could fit on a chipBY MIKE WILLIAMS
Rice News staff

To stand a ribbon of graphene upright, it needs diamond on the soles of its shoes.

A new paper by collaborators at Rice University and Hong Kong Polytechnic University demonstrates the possibility that tiny strips of graphene -- one-atom-thick sheets of carbon -- can stand tall on a substrate with a little support. This leads to the possibility that arrays of graphene walls could become ultrahigh density components of electronic or spintronic devices.

media.rice.edu

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From: DanD9/26/2011 4:07:49 PM
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A new challenger to grapheneGraphene, which consists of a single layer of carbon atoms, has been heralded as tomorrow's super material for fast electronics and earned a Nobel Prize for its discoverer. Now two teams of researchers at LiU have each posed a solution that addresses how to progress and develop similar materials that retain even better properties.


http://www.liu.se/forskning/forskningsnyheter/1.289736?l=en

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From: DanD9/26/2011 4:11:50 PM
1 Recommendation   of 246
 
Your flexible friend? Samsung to release bendy-screened phones 'in Spring 2012' - so tough they can be hit with a hammer


By Rob Waugh


Last updated at 1:53 PM on 26th September 2011





The Galaxy Skin phone will be so flexible you can roll it up - and may be in shops early next year


Demonstrations of 'bendable' screens have been a staple of technology shows ever since there were screens small enough for us to carry.


This week, Samsung has given the strongest sign yet that the hi-tech devices might become reality.

The company demonstrated 'bendable' AMOLED screens 4.5 inches across and just 0.3mm thick in January this year.

Reports this week hint that phones using the technology - which can be 'rolled up' and survive hammer blows - will appear in the second quarter of next year.

The technology relies on atom-thick layers of 'graphene' - sheets of carbon atoms - sandwiched together, protecting a layer of liquid crystal 'screen'.


Earlier this year, reports leaked that Samsung had the capacity to manufacture large amounts of the screen by 'early 2012' - but no one knew what they might be for.

Samsung later released pictures of a concept phone using the technology - the Galaxy Skin.


The phone would be no mere novelty.


Phones using Graphene screens would be practically unbreakable, and offer an instant advantage over every other smartphone on the market.

Now, according to reports in the International Business Times, the handsets could be on sale early next year.


The report was remarkably specific, stating that the handset would offer specifications including a high-resolution 800×480 flexible AMOLED screen, eight megapixel camera and 1Gb of RAM as well as a 1.2GHz processor.


Those specifications sound suspiciously similar to the spec of Samsung's current flagship, the Galaxy S II, however.


Will Findlater, editor of Stuff magazine told Mail Online today, 'AMOLED is already the mobile screen technology to beat, so if it’s as good as promised, flexible AMOLED could put an end to smashed smartphone displays - and tablets, which are even more fragile.'





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