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Lecture: Nano-material: Graphene: Narrator: Listen to part of a lecture in a material science class. Professor: So basically, uh, nano material is an extraordinary thin sheet of material often a film or and engineered surface is sometimes that's less than 5 atoms thick. There's a number of different nano materials out there right now. But what I'd like to focus on today is graphene. Now I like graphene as little number of exciting applications where it may prove very beautiful. As its name suggest, graphene derived from graphite, the stuff in the core of pencil. Graphics made of layers of carbon atoms, and if you strip off the thinnest possible layer of graphite, a layer that's just one atom thick, you got that thing. Graphene is the strongest material ever made. Its strength is due to a perfect crystalline atomic structure, which looks like chicken wire under the microscope. Actually, you could compare graphite to diamond, because they're both made of carbon atoms that are arranged in a simple and regular pattern. But unlike diamond, graphene is incredibly flexible, akin to plastic wrap. And because of that atomic structure, graphene is also an outstanding heat conductor, electrons speeds through this material much faster than they can do other materials. Um, It's been a few decades since graphene was first identified as a potential nano material. In 1947, the graphene scientists came up with the idea that a material like this could be used in a variety of ways, but others were skeptical. Because really, how do you make a sheet of material that's just one atom thick. In the 1980s and 90s, many researchs tried to produce graphite with little success. The final of 2004, a group in Manchester England, created the first graphene sample like simple mechanical explanation. Basically, they placed a small piece of graphite between two pieces of adhesive tape, hold the tapes apart, and repeated this process over and over until they had extracted a layer that was just one atom thick. As this news excited the scientific community, because now, we meant the dress needs to be investigated not only theoretically but also experimentally. When experiments revealed the high mobility of electrons from that scene, this material became particularly promising in the field of electronics. We might be used to make transistors in computer microchips. As you know, the development of microchips and transistors has been based on silicon for more than forty years. The total of the material that allowed us to create ever faster and smaller microchips, which transform computers from huge machines to small portable devices. But as mobile phones, music players, other devices keep getting smaller and faster without pushing the capacity short. So we hope the graphene can eventually replace silicon as a semiconductor. But there's another challenge, the industrial production of graphene sheets, what he did take method is good for producing small samples for recent purpose. But we need a reliable way to mass produce graphene in large sheets, so it can be sold to companies that manufacture transistors, for example. And several groups are investigating ways to do this to make large quantities of graphene cost effective. As you know, a semiconductor is a material that delivers electrical charges between electrons. We call that the basic units of digital information are one and zero: one means that there is a signal, zero means that there is no single. And this is the way we code and transmit data digitally. So the basic rule for semiconductor is that it can convey a signal that this signal can also be stop. And here is one problem of graphene – it's too good a conductive. Its conductivity is so good that the signal cannot be turned off. So we're investigating ways to control. That means productivity to halt the flow of electrons through this material.