A Remarkable Discovery In Materials Science

AN AMAZING new type of ultra-thin material - that has the potential to speed future scientific discoveries and save billions of dollars - has been recognised as a “remarkable contribution” to science with the award of one of the UK’s top science prizes. It has even been suggested that “everyone might eventually be influenced” by the material.

Known as graphene, it has already been used to test Einstein’s theory of relativity in a table-top experiment using low-cost laboratory equipment. Until then, it was only possible to test the famous theory by building expensive machinery or by studying stars in distant galaxies.

Andre Geim, the University of Manchester researcher who led the team that discovered the material, has been awarded the 2007 Mott Medal and Prize by the Institute of Physics for his ground-breaking work.

The efforts of Professor Geim of the School of Physics & Astronomy - along with Dr Kostya Novoselov and colleagues at the university and at the Institute for Microelectronics Technology in Chernogolovka, Russia - led to the discovery of a new class of materials called two-dimensional atomic crystals in 2004.

But it is graphene that has caused a real stir in the world of science. Comprising a single layer of carbon atoms densely packed in a honeycomb crystal lattice, the material is made by splitting graphite into individual atomic planes, through a process described by the scientists as similar to tracing with a pencil. The resulting atomic sheet is unexpectedly stable, highly flexible and strong, and highly conductive.

One of many unique properties of graphene, that previously only existed in science fiction, is that its electrons mimic particles moving with the speed of light. It is this feature that presents scientists with an easy way to study relativistic phenomena.

Professor Geim and his team have also found that graphene exhibits another remarkable quality, in that within it electrons can travel without any scattering over submicron distances. This is important for making very fast switching transistors.

In the quest to make the computer chip more powerful and faster, engineers are striving to produce smaller transistors, shortening the paths that electrons have to travel to switch the devices on and off.

Ultimately, scientists envisage transistors made from a single molecule, and Professor Geim’s work has brought that vision nearer. In the future, it could lead to a computer being carved entirely out of a single sheet of graphene.

“It is certainly nice and somewhat unexpected to be acknowledged at such an early stage,” said Professor Geim. “Although it was found only two years ago, graphene has proved itself as a truly remarkable material, with a wealth of new physics coming out.

“It is too early to speak about real applications. But all the indications are that graphene will be not just another new material but will find a multitude of applications so that everyone might eventually be influenced by this discovery,” he added.

“This and the many other two-dimensional materials that can be produced open up practically infinite possibilities for uses which people have never even thought of yet. These materials are lightweight, strong and flexible, and there is a huge choice of them. This is not only about smart gadgets. Like polymers whose pervasiveness changed our everyday life forever, one-atom-thick materials could be used in a myriad of routine applications from clothing to computers,” said Professor Geim.

The technique used to split the planes of atoms is called micromechanical cleavage. Depending on a parent crystal, their one-atom-thick counterparts can be metals, semiconductors, insulators, magnets and so on. Previously, it was thought that such thin materials could not exist in principle but the research team has, for the first time, demonstrated that they are not only possible but indeed are fairly easy to make.

Dr Novoselov, a key investigator in the research, added: “Probably the most important part is that our discovery is not limited to just one or two new materials. It is a whole class of new materials, thousands of them. And they have a variety of properties, allowing one to choose a material most appropriate for a particular application.”

Professor John Durell, head of the School of Physics & Astronomy, said: “We are delighted that the outstanding research work of Andre Geim and his team has been recognised by the award of the Mott Medal and Prize by the Institute of Physics. The discovery of graphene has led to the creation of a new and exciting ‘laboratory’ for the study of fundamental science. Future development of production techniques could lead to applications with the potential to revolutionise electronic devices.”

Graphene belongs to the family of fullerene molecules that were discovered during the last two decades. It is in fact the first two-dimensional fullerene. The Manchester researchers have been concentrating on its electronic properties. By employing the standard microfabrication techniques used, for instance, in manufacturing of computer chips, the team has created a type of field-effect transistor, a vital computer component.

In terms of applications, the sort of property demonstrated by graphene can only be compared with that demonstrated by some nanotubes, said Professor Geim, adding: “Because carbon nanotubes are basically made from rolled-up narrow stripes of graphene, any of the thousands of applications currently considered for nanotubes renowned for their unique properties can also apply to graphene itself.”

Although the researchers are dealing with patches of graphene that are very small - and computer engineers will need graphene wafers a few inches in size - Professor Geim said the prospects were good because there are no fundamental limitations on the lateral size of graphene sheets. Dr Novoselov added that only 10 years ago carbon nanotubes were less than a micron long. Now, scientists could make nanotubes several centimetres long, and similar progress could, he said, reasonably be expected for graphene as well.

David Glover, from the University of Manchester Intellectual Property company, commented: “This is clearly an exciting breakthrough with huge potential and, with development, graphene could soon compete in many niche markets where low-energy consumption and high-electron mobility are paramount requirements.”

英国在材料科学领域有重大发现

科学家发现了一种全新的超薄材料，它很可能会加速未来科学发现的进度，而且可以节省数十亿美元的资金。这个发现被誉为科学界“非凡的贡献”，获得了一个在英国科学界享有极高殊荣的奖项。据说，最终每个人的生活都会受到这种材料的影响。

这个新发现的材料被命名为“Grapheme”，已经用来对爱因斯坦的相对论进行论证，而且试验设备的花费非常低廉。此前，要对著名的相对论进行论证，必须要通过建立昂贵的试验设备，或是研究遥远的星系来完成。

.领导此次发现新材料工作小组的是曼彻斯特大学研究员Andre Geim，他是物理和天文学 院的教授。出于对其卓越研究贡献的表彰，英国皇家物理学会（Institute of Physics）向他颁发了“2007年莫特奖章和奖金（Mott Medal and Prize）”。

正是在Geim教授、Kostya Novoselov博士、曼彻斯特大学内的其他同事及俄罗斯琴诺格洛夫微电子科技研究所（Institute for Microelectronics Technology in Chernogolovka, Russia）的共同努力下，2004年，一系列叫做二维原子晶体（two-dimensional atomic crystals）的新材料被发现了。

但是，graphene的发现无疑在科学界激起了千层浪。grapheme是指一层密集的、包裹在蜂巢晶体点阵上的碳原子。在被科学家们描述为与“ 削铅笔”相似的过程中，使石墨爆裂成单独的原子面，于是graphene就产生了。这些原子碎片异常的稳定，而且具有很高的弹性且十分坚固，同时传导性也极好。

在graphene众多的特性中，其中有一个是它的电子可以像粒子那样以光的速度进行移动，这以前只在科幻小说中描述过。正是它的这个特性，使得科学家们能够更加容易地来研究相对论现象。

它还具有另一种显著的特性，也因此，它里面的电子可以不通过散射而进行亚微细距离移动。这种特性对于制造需要快速转换的晶体管很重要。

为了使计算机芯片更加强大，速度更快，工程师们一直在追求生产更小的晶体管，减短电子驱动机器开关时需要移动的距离。

最终，科学家们得出了以一个分子来制作一个晶体管的设想。而Geim教授的工作为他们将设想转化为现实带来了希望。将来，一台电脑可能只是由单一的一个graphene片来制成。

Geim说：“在还处于研究的初级阶段时期，情况看起来喜人，而且进展得有些出人意料。虽然graphene的发现不过两年，但是，事实证明graphene的确是一种值得关注的材料，同时它还带来了很多新的物理学研究方向。”

Geim教授解释说：“现在就说到具体的应用，似还嫌早了些。但是，所有的迹象都表明，graphene不仅仅是一个新材料，它将会出现在许多应用当中。到最后，我们会发现，这个新发现将影响到每个人的生活。”

接着他又说：“这种以及其他许多可以进行生产的二维材料，开启了实际使用无限事物的可能性，而这是人们连想也未曾想到过的。这些材料既轻又坚固，且弹性好，而且还大量存在，不仅仅用于制造小器件上。像聚合体被普遍使用，乃至改变了我们的生活一样，一个原子那么厚的材料，可以应用到我们日常生活从衣物直到计算机的每一个方面。”

用来将原子爆裂成原子面的技术叫做“微机械力分裂法”。由于爆裂需要的是双晶体物质，所以这种一个原子厚度的材料来源可以是金属、半导体、绝缘体、磁体等等。以前，原则上认为这么薄的材料是不可能存在的， Geim教授的研究小组第一次证明这种材料是存在的。他们的研究不仅显示了存在的可能性，而且还证明了是很容易就可以制造出来的。

Novoselov博士是这个工作小组中的重要一员，他说：“大概，我们的工作最重要的不仅仅是局限在发现了一两种新材料，而是一系列数以千计的新材料。而且他们具有多种特性，可以让我们为某个特定应用而选到最适合的材料。”

物理和天文学院的院长John Durel教授说：“我们对Andre Geim及其小组卓越的研究工作表示欣喜，他们的成就得到了英国皇家物理学会的认可，并被授予了莫特奖章和奖金。Graphene的发现引发了新的实验室的建立，从而促进基础科学研究，而未来产品技术将引起革命性电子装置向开发实际应用潜力方向发展。”

Graphene属于富勒烯分子家族――在过去20年中发现的一种新物质――是第一个实际上的二维富勒烯。曼彻斯特大学的研究人员把注意力都集中在研究它的电子特性上。例如，通过运用微细加工技术来制造计算机芯片时，工作小组创造出了一种场效应晶体管，它是计算机中一个重要的组成部件。

在运用方面，graphene表现出来的特性只有某些纳米管才能与之相比。Geim教授接着说：“因为碳纳米管基本上是由积聚的窄带graphene制造，在数以千计目前应用的纳米管中所体现出来的任一特性，graphene也都具有。”

虽然，这个研究处理的都是一些极小的graphene片，但是计算机工程师所需要的仅仅是这些graphene晶片的几分之一英寸就够了。Geim 教授表示前景是乐观的。因为对graphene片的边缘尺码基本没有限制。Novoselov博士也补充说明，仅仅在10年前，碳纳米管的长度还不足1微米。现在，科学家们已经可以制造出长几厘米的纳米管。我们可以预见，同样的道理也会出现在graphene应用上。

来自曼彻斯特大学知识产权公司的David Glover说：“很显然的，这是一次具有突破意义 的发现，graphene具有巨大的潜力和发展前景。它很快就会进入低能源消耗和高电子迁移率需求极为重要的市场去竞争，瞄准机会，大放异彩。”