[00:00.00]Narrator:Listen to part of a lecture in a materials science class.[00:06.20]Professor:So basically, a nanomaterial is an extraordinary thin sheet of material, often a film or an engineered surface sometimes that’s less than five atoms thick.[00:21.30] There is a number of different nanomaterials out there right now but the one I’d like to focus on today is graphene.[00:28.70] Now, I like graphene because there’s a number of exciting applications where it may prove very useful.[00:36.20] As the name suggests, graphene is derived from graphite, the stuff in the quart of pencils.[00:43.40] Graphite is made of layers of carbon atoms and if you strip off the thinnest possible layer of graphite, a layer of just one atom thick, you’ve got graphene.[00:54.90] Graphene is the strongest material ever made. Its strength is due to its perfect crystalline atomic structure, which looks like chicken wire under a microscope, actually.[01:07.40] You could compare graphene to diamond because they’re both made of carbon atoms that are arranged in a simple and regular pattern.[01:15.90] But unlike diamonds, graphene is incredibly flexible, akin to plastic wrap.[01:22.80] And because of its atomic structure, graphene is also an outstanding heat conductor.[01:29.00] Electrons speed through this material much faster than they can through other materials.[01:35.00]It’s been a few decades since graphene was first identified as a potential nanomaterial in 1947, to be precise.[01:44.00] Some scientists came up with the idea that a material like this can be used in a variety of ways but others are skeptical because really, how do you make a sheet of material that’s just one atom thick?[01:58.50] In the 1980s and 90s, many researchers tried to produce graphene with little success.[02:05.70] But finally, in 2004, a group in Manchester, England created the first graphene sample by simple mechanical exfoliation.[02:15.90] Basically, they placed a small piece of graphite between two pieces of adhesive tape, pulled the tapes apart and repeated this process over and over until they had extracted a layer that was just once atom thick.[02:31.50] And this news excited the scientific community because now it meant the graphene could be investigated not only theoretically, but also experimentally.[02:42.70] When experiments revealed the high mobility of electrons through graphene, this material became particularly promising in the field of electronics.[02:53.70] It might be used to make transistors and computer microchips.[02:58.40] As you know, the development of microchips and transistors has been based on silicon for more than forty years.[03:06.70] Silicon was the material that allowed us to create ever faster and smaller microchips which transformed computers from huge machines to small portable devices.[03:19.50] But, as mobile phones, music players, and other devices keep getting smaller and faster, we’re now pushing the capacity of silicon so we hope that graphene can eventually replace silicon as a semi-conductor. [03:34.60]But there’s another challenge: the industrial of graphene sheets.[03:39.60] The adhesive tape method is good for producing small samples for research purposes.[03:45.60] But we need a reliable way to mass produce graphene in large sheets so they can be sold to companies that manufacture transistors, for example.[03:56.70] And several groups are investigating ways to do this, to make large quantities of graphene cost effectively.[04:04.40] As you know, a semi-conductor is a material that delivers electrical charges between electrons.[04:11.50] Recall that the basic units of digital information are ones and zeros.[04:16.70] One moves means that there is a signal and there is no signal. And this is the way you code and transmit data digitally.[04:26.80] So, the basic rule for a semi-conductor is that it can convey a signal, but this signal can also be stopped.[04:34.40] And here is one problem with graphene. It’s too good a conductor.[04:38.90] Its conductivity is so good that the signal cannot be turned off.[04:44.00] So, we’re investigating ways to control graphene’s conductivity to halt the throe of electron through this material.
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