| 查看: 879 | 回复: 3 | ||||
| 当前主题已经存档。 | ||||
graduate3木虫 (正式写手)
无业游“虫”！
|
[交流]
碳纳米建材开创先进电气性能研究的可能性（图）！
|
|||
|
Carbon nanotube building blocks open up possibilities for advanced electronics A new method to systematically modify the structure of single-walled carbon nanotubes could expand their electronic properties and open the path to nano-electronics. Carbon cylinders a few billionths of a meter in diameter and a few microns long, these nanotubes are one of the strongest structures known and have unique electrical and thermal properties. This promising method to add defects to carbon nanotube walls was developed by researchers at the U.S. Department of Energy's Argonne National Laboratory, who are interested in improving the materials for thermoelectric power generation, the use of heat differences to generate electricity. Thermoelectric conversion is the principle behind thermocouples, thermal diodes and solid-state refrigerators. "If you change the electronic structure," said Argonne chemist Larry Curtiss, "by adding defects in an ordered way, theoretically you can make more efficient thermoelectric materials. So we could produce electricity more efficiently from solar, nuclear or any thermal power generation." Curtiss is group leader of the Molecular Materials Group in Argonne's Materials Science Division. One dimer at a time Creating defects by adding molecules to nanotubes is challenging because of their extremely small size. And researchers are seeking a controlled, reproducible method. So the Argonne team, which includes Curtiss, Michael Sternberg, Peter Zapol, Dieter Gruen, Gary Kedziora, Paul Redfern and David Horner, used computer simulation tools to learn how to add a single carbon dimer – a molecule of two bonded carbons – to a single-walled carbon nanotube. The single-walled nanotubes – believed to be the best candidates for next step of miniaturizing modern electronics – resemble a long tube of chain-link fence made of hexagons. The Argonne team simulated a variety of approaches to attach the carbon dimer to the nanotube. They found the easiest and strongest method is by horizontally inserting a carbon dimer into two hexagonal bonds, creating two adjacent pentagons and heptagons (seven-sided structures) in the chain link. One dimer, two dimer… After they understood how to add one dimer, the researchers began to add dimers in patterns. "The interesting thing was going into the multiple patterns," Curtiss said. "We started building up patterns using the dimers like building blocks and adding them to the tubes." The researchers found a number of interesting modifications: -- The "bumpy" tube has carbon dimers added symmetrically around the circumference of the tube to create a stable bulge. -- The "zipper" tube has dimers added horizontally along the axial direction to every other hexagon, creating alternating single octagons and pairs of pentagons. -- The "multiple zipper" tube has six axial "zippers" spaced by hexagon rows around a tube. "The structures we simulated," said physicist Zapol, "have new and unexpected features. They modify the electronic properties in the nanotubes, and that will be useful in future electronic applications." Guided by the simulations, Argonne materials scientists, led by Gruen, with expertise in carbon nanomaterials are creating materials for testing. "But we think that some of these structures exist already," said Curtiss. Zapol's literature review revealed that some researchers have found these structures, but they did not know what they were. The zipper structure particularly appeals to Argonne researchers because the atomic spacings in the openings are just the right size to bond nanotubes to Ultrananocrystalline™ diamond and combine the properties of both. Ultrananocrystalline diamond is a novel form of nanocarbon developed by Argonne that has many of the properties of diamond – the hardest known material on earth – and can be deposited on a variety of surfaces. Unlike diamond, its properties can be optimized depending on the application. Researchers plan to use the carbon nanotubes as a scaffolding to attach other molecules and study their functions. They will also connect the tubes into arrays and study the effects. Source: by Evelyn Brown, Argonne National Laboratory （转自PHYSORG.COM） 附件图片说明： Nanotube designs include (from top) "bumpy," "zipper" and "multiple zipper." |
回复此楼» 收录本帖的淘帖专辑推荐
 热电相关 |
» 猜你喜欢
应该是93bebmhtak前后十一个字符比较关键
已经有32人回复
-
2019年青年基金涵评意见，大家看看几个A，几个B?
已经有5人回复
-
职称评审，求友友推荐见刊最快的期刊
已经有4人回复
-
奇怪，两个人的filecode固定段从头到尾一模一样
已经有10人回复
-
综述论文作为代表作会不会影响评审专家的印象分？
已经有13人回复
-
是这周出结果还是下周出结果？
已经有3人回复
-
小木虫上这么多卖论文的，真有人买论文么？感觉没必要啊
已经有9人回复
-
有时候，自然基金真的不能太认真 （我的申报经验）
已经有4人回复
-
帮忙看看fileCode
已经有13人回复
-
为什么网上很多人说本周 12号出结果
已经有7人回复
» 本主题相关商家推荐: (我也要在这里推广)
bioman
木虫之王 (著名写手)
- 应助: 7 (幼儿园)
- 贵宾: 0.4
- 金币: 82261.8
- 散金: 6
- 红花: 43
- 帖子: 2210
- 在线: 803.5小时
- 虫号: 472
- 注册: 2003-03-02
- 专业: 功能与智能高分子
2楼2006-07-07 19:01:30
0.5
 |
3楼2006-08-27 10:37:11
westwolf
木虫 (著名写手)
- 应助: 3 (幼儿园)
- 贵宾: 2.5
- 金币: 3732.4
- 散金: 954
- 红花: 5
- 帖子: 1338
- 在线: 55.4小时
- 虫号: 120650
- 注册: 2005-12-03
- 性别: GG
- 专业: 无机非金属基复合材料
4楼2006-08-27 10:41:35
