탄소나노튜브

탄소나노튜브(CNT)는 직경이 0.4 nm 정도이고 길이가 수 나노미터에서 최대 1 밀리미터인 관 모양의 탄소입니다.

탄소나노튜브

Carbon nanotubes were discovered in 1991 by Sumiyo Iijima, a Japanese scientist working at the NEC Corporation. A carbon nanotube (CNT) is a tubular form of carbon with a diameter as small as 0.4 nm and length from a few nanometers up to a millimeter.  The length-to-diameter ratio of a carbon nanotube can be as large as 28,000,000:1, which is unequalled by any other material.

Carbon exists in several allotropes (different physical forms) including graphite and diamond which are the most familiar. To imagine the structure of a carbon nanotube, think about taking a single layer of a graphite sheet, cutting it into a long rectangular piece, and curling it up so the long edges of the rectangle join one another.  The result is a single-wall carbon nanotube (SWCNT). If you take multiple layers of a graphite sheet, then you get a multiwall carbon nanotube (MWCNT).

Of course, no one is sitting out there rolling graphite sheets in order to make nanotubes. These are grown in laboratories often using a process called chemical vapor deposition.

This process can be carried out using instruments called reactors that can be quite sophisticated, but carbon nanotubes can be made in a standard chemistry laboratory relatively easily. A quartz tube about 2.5 cm in diameter serves as the reactor vessel and is inserted inside a furnace (a furnace is a standard heating device for synthesizing and treating materials). The nanotube is grown on a silicon wafer that is placed at a central location inside the quartz tube. A thin layer of iron or nickel or cobalt is applied to the silicon wafer to serve as a catalyst to grow the nanotubes. A hydrocarbon such as methane or ethane or acetylene is sent through the reactor tube which is heated to 750-900ºC by the furnace.

Continue to explore nanomaterials by reading about other examples of materials that exhibit interesting properties on the nanoscale: 무기 나노와이어덴드리머나노입자그래핀, 그리고 양자점.

그래핀 튜브의 3d 그림 구조입니다. 이미지 출처: Rost-9/bigstock.com

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