UNDERSTANDING A PRINTED TEXT.
| Nanotechnology primer: graphene - properties, uses and applications | ||
| Existing forms of carbon basically consist of sheets of graphene, either bonded on top of each other to form a solid material like the graphite in your pencil, or rolled up into carbon nanotubes (think of a single-walled carbon nanotube as a graphene cylinder) or folded into fullerenes. The reason nanotechnology researchers are so excited is that graphene and other two-dimensional crystals – it's called 2D because it extends in only two dimensions: length and width; as the material is only one atom thick, the third dimension, height, is considered to be zero – open up a whole new class of materials with novel electronic, optical and mechanical properties. Early experiments with graphene have revealed some fascinating phenomena that excite researchers working towards molecular electronics. For instance, it was found that graphene remains capable of conducting electricity even at the limit of nominally zero carrier concentration because the electrons don't seem to slow down or localize. The electrons moving around carbon atoms interact with the periodic potential of graphene’s honeycomb lattice, which gives rise to new quasiparticles that have lost their mass, or 'rest mass' (so-called massless Dirac fermions). That means that graphene never stops conducting. It was also found that they travel far faster than electrons in other semiconductors. Graphene is undoubtedly emerging as one of the most promising nanomaterials because of its unique combination of superb properties, which opens a way for its exploitation in a wide spectrum of applications ranging from electronics to optics, sensors, and biodevices | ||
| Graphene-based nanomaterials have many promising applications in numerous areas: | ||
| Energy Graphene-based nanomaterials have many promising applications in energy-related areas. Just some recent examples: Graphene improves both energy capacity and charge rate in rechargeable batteries; activated graphene makes superior supercapacitors for energy storage; graphene electrodes may lead to a promising approach for making solar cells that are inexpensive, lightweight and flexible; and multifunctional graphene mats are promising substrates for catalytic systems. | ||
| Sensors Functionalized graphene holds exceptional promise for biological and chemical sensors. Already, researchers have shown that the distinctive 2D structure of graphene oxide (GO), combined with its superpermeability to water molecules, leads to sensing devices with an unprecedented speed. Nanoelectronics Some of the most promising applications of graphene are in electronics (as transistors and interconnects), detectors (as sensor elements) and thermal management (as lateral heat spreaders). The first graphene field-effect transistors (FETs) – with both bottom and top gates – have already been demonstrated. At the same time, for any transistor to be useful for analog communication or digital applications, the level of the electronic low-frequency noise has to be decreased to an acceptable level (graphene transistors can work without much noise). Transistors on the basis of graphene are considered to be potential successors for the some silicon components currently in use. Due to the fact that an electron can move faster through graphene than through silicon, the material shows potential to enable terahertz computing. Coatings Coating objects with graphene can serve different purposes. For instance, researchers have now shown that it is possible to use graphene sheets to create a superhydrophobic coating material that shows stable superhydrophobicity under both static as well as dynamic (droplet impact) conditions, thereby forming extremely water repelling structures. Research findings also have established graphene as the world's thinnest known coating for protecting metals against corrosion. It was found that graphene, whether made directly on copper or nickel or transferred onto another metal, provides protection against corrosion. Another novel coating application is the the fabrication of polymeric AFM probes covered by monolayer graphene to improving AFM probe performance. (http://www.nanowerk.com/spotlight/spotid=34184.php) | ||
| CONTROLLED PRACTICE I. Choose the correct option and answer the questions. 1. An atomic-scale honeycomb lattice made of carbon atoms is called… A graphite B fullerene C graphene D nanotube 2. The reason nanotechnology researches are so excited about graphene is that… A it is the only two-dimensional crystal B it provides the opportunity of producing materials with new electronic, optical and mechanical properties C it is the mother of all graphitic forms D it extends in only two dimensions 3. Why the graphene never stops conducting? A because of its solid structure B because it is a two-dimensional crystal C because of the peculiarities of its electrons’ movement D because of its mechanical properties 4. Find a synonym to the term “hazardous waste” A harmful waste B accidental waste C normal waste D unexpected waste 5. Why does graphene have a promising application in rechargeable batteries? A it improves their lifetime B it improves their energy capacity C it improves their charge rate D it improves both energy capacity and charge rate II.Decide whether the following statements are true or false and prove your answer by citing the article. 1. Graphene reduces the productivity of sensing devices by slowing them down. 2. A new type of transistors – graphene field-effect transistors (FETs) – is to be presented to the public in 2016. 3. In the future graphene will replace some silicon components of the transistors. 4. Graphene is an ideal material for transistors. It has no disadvantages. 5. Graphene can give coating material exceptional waterproof properties. III. Make up a summary of the article using special expressions from appendix on p. 47. IV. Work in pairs. Make a list of all the advantages of graphene. V. Divide into small groups of three or four. Each group should choose one area of application of graphene (energy, sensors, nanoelectronics, or coatings), find additional information at home and make a small presentation about this area of application. Present your findings in class. | ||
Lesson II
WORD-STUDY
Exercise 1. Check the transcription in a dictionary, read and translate the words listed below.
Nouns
Derivation, ancestor, coating, utensil
Verbs
Refer to, coin, harness, exploit
Adjectives
Aquatic, water-repellent, self-cleaning, nonwetting
Exercise 2. Match Russian and English equivalents.
|
Дата добавления: 2016-03-27; просмотров: 698;