Concrete may have found it's killer app in graphene with its amazing potential for a quantum computer - a new way of processing data in real-time - or just plain faster computers. "It's a much better conductor of electricity," said Paul McEuen, a physicist at Cornell University and member of the team who is studying graphene. "It could allow us to make very fast transistors." McEuen predicts that graphene could become the "it material" that drives the computing market.
"They believe, with good reason, that if graphene had been invented 10 years ago, it would have gotten a huge amount of interest. It would have been the basis for a lot of technologies - digital storage, faster devices, more capable devices, etc.," said John Whelan, the author of a 2005 paper that described the wonder material. "But its potential is so great, it has become the focus of a lot of attention."
The "It" Material: What Is Graphene?
It is the best thing since sliced bread or sliced bread with pepperoni. And that's a good thing.
Or is it? "Graphene looks like a sheet of flexible cellophane - something really mundane," said McEuen. "But it is a million times stronger than steel and 300 times more conductive than copper. And all of these properties make it very promising."
That seems obvious. So what's the fuss? Graphene was discovered 20 years ago, and now it's all over the science and technology news pages. So what is this magical material that scientists, physicists, and engineers around the world have flocked to?
It is - as the name implies - a one-atom-thick sheet of carbon that is completely flat and seamless. It is highly crystalline, which means it conducts electricity very well. It is flexible and can be molded into almost anything. It is also inexpensive to produce and environmentally friendly. And its electronic properties could be very valuable.
In 1998, researchers at the University of Manchester in England described a new carbon allotrope, a single layer of carbon atoms, that could be stacked like a sheet of graph paper. This was not a fluke. The discovery was the result of theoretical work the professors published in the journal Physical Review B in 1986. They were experimenting with carbon allotropes.
"You can think of allotropes as carbon molecules that are all the same except for one thing. With graphite and diamond, it's the direction the carbon atoms are oriented. There is only one direction possible - except in graphite, where there are many directions in which it can bend. With nanotubes, there are many different radii that you can get that are all the same except for the direction," said Mark Hersam, an associate professor of chemistry at Penn State who is doing research on graphene. "With graphene, it's just a flat, one-atom thick sheet of carbon. When you stack one on top of another, it's always a single, plane sheet."
Hersam explained that the discovery occurred in the early 1980s with the advent of high resolution electron microscopes. These high-resolution microscopes could see something as small as a half-nanometer - about 100,000 times thinner than a human hair. These microscopes were built to observe semiconductor wafers or the surface of semiconductors, so they were not really built to do very high-resolution pictures of carbon atoms.
Yet that is what researchers found. In 1999, Andre Geim and Konstantin Novoselov, both researchers at the University of Manchester, published a paper in Science where they observed a material called "buckytubes." At the time, few people thought much of this paper. It was not until seven years later that Geim and Novoselov published another paper in the journal Nature that went viral. Their 1999 paper went for over 20 pages, and in 2010 their 2010 paper went for 14 pages.
The discovery of graphene was very exciting to people around the world. A team of University of Manchester researchers have written a book titled Graphene: Graphite, Graphene, Graphite 2, and it is all about this new and unique carbon allotrope. Geim and Novoselov, who published their work in Nature, are now a leading pair of researchers in this new realm of research. They hold world records for having the most citations to a single publication (more than 5,000). Both hold more than 3,000 citations to a single publication.
"People were able to take some observations that were made through the '80s and '90s and basically prove that some material called graphene existed. And after that it wasn't just another material - it was the biggest news in chemistry in a very long time," Hersam said.
Once they proved that graphene existed, there were a lot of questions about its properties. What else did it have in its realm of properties? How thick could you make the material? Could you make it really thin, but not be two-dimensional?
"The answer is yes," Hersam said.
Today, it is possible to create graphene films that are 2 to 5 micrometers thick (a micrometer is one-millionth of a meter). In 2011, researchers discovered they could make one-atom-thick sheets of graphene called graphene nanoribbons. These ribbons could be twisted and curled into tubes. In 2011, Hersam and his team were able to create graphene sheets that were thinner than a sheet of paper. The sheets are so thin, they are actually transparent. Today, the only way to study graphene sheets is with the help of a scanning tunneling microscope or an atomic force microscope. However, Hersam explained that a scanning tunneling microscope only goes up to about 3 nanometers.
Other researchers have been able to create a single-atom-thick sheet of carbon that is flexible. "It can be stretched, rolled, or folded and no one has seen any changes in properties. It's like having a really big piece of plastic that's only one atom thick. They are called, by some people, molecular-scale engineering," Hersam said.
When researchers started to discover new properties about graphene, it became obvious that they should continue to work on it. Scientists created a process that will make graphene out of coal or any other material you have lying around the house. And to think that these properties could be applied to computer technology. Imagine how much easier it could be to store data on the new ultrathin, flexible, and highly conductive sheets of carbon. And graphene's potential is not limited to computers. The possibilities are endless.
What are the graphene properties? A carbon allotrope that is strong, transparent, flexible, flexible, and can be molded into any shape. Researchers have developed a process that makes graphene out of coal or other inexpensive materials found around the world.
Other researchers are exploring the applications for transparent, conductive graphene films that could replace indium tin oxide films (ITO), which are currently used in touch screens in cell phones and tablets. Some of the applications they are exploring are touch screens, displays, and biomedical and electronic devices.
Researchers have even reported that there is a way to print graphene inks onto flexible substrates, and produce flexible circuits. "You can literally print on anything. In principle, it's going to be printed on a lot of electronic devices, including cell phones, which is a completely different thing from seeing this in the lab," Hersam said. "You can make these inks out of graphene or graphite - really, any of these carbon-based materials that exist. So I think that's going to be the big area - printing the inks."
Because of graphene's low weight and flexible properties, it could also be used for more energy-efficient aerospace applications. Today, graphene is used in airplane wings, which is a good indication that it will soon be used to make jet engine technology even more efficient.
Other researchers are exploring using graphene to construct supercapacitors (also called energy storage devices) that can be used for flexible electronics and batteries. "Batteries and supercapacitors are on opposite ends of the spectrum," Hersam said. "A supercapacitor can charge and discharge very quickly, and they have potential for very high energy storage capability. If you build one of those devices out of graphene, you can get very high power densities. You are trying to build a device that will store power for a little bit of time, and also have high power capability."
So far, researchers have only been able to produce thin sheets of graphene. One researcher, Andre Geim, theorized that if a graphene sheet was stretched in one direction, it would split into two different sheets. This was one of the original questions that people asked about graphene, whether graphene could be stretched to extreme amounts and still remain a sheet.
What they discovered, however, was that graphene can stretch to extreme amounts, and it is not a single sheet. "You can make a piece of graphene that's as big as you want," Hersam said. "It can stretch to over 10 percent." He explained that graphene may be made out of carbon, but it is not carbon. "There are some people out there that would argue that this is an allotrope of carbon. And there's another school of thought that would argue that it's all carbon in some sort of configuration that is different than what you would expect out of the structure of carbon. We do not know for certain. We think it's a material of carbon, but we don't know exactly what it is. What we know is that there are some
