Wigner defects bridge the graphite gap
Wigner defects bridge the graphite gap
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DOI：
10.1038/nmat876
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发表时间：
2003-05
期刊：
影响因子：
41.2
通讯作者：
R. Telling;C. Ewels;A. A. El-Barbary-A.;M. Heggie
中科院分区：
文献类型：
--
作者：
R. Telling;C. Ewels;A. A. El-Barbary-A.;M. Heggie
我们目前的结构，能量和辐照石墨碳材料中的缺陷的行为的调查结果。石墨慢化剂中由于高能核辐射而产生的缺陷通常与内部能量、微观结构和物理性质的不期望的变化有关--所谓的维格纳效应。另一方面，控制引入和处理电子束中的此类缺陷的能力被认为是设计碳纳米结构特性的理想方式。在这两种情况下，结构和相互作用的原子级细节才刚刚开始被理解。在这里，使用模型系统的结晶石墨，我们显示从第一性原理计算，新的细节的行为的空位和间隙缺陷。我们确定了一个突出的势垒状态的能量释放，揭示了一个令人惊讶的能力空缺缺陷，以弥合广泛间隔的原子层，并讨论在辐照过程中的物理性质和微观结构的变化，包括与位错的相互作用。
We present findings on the structure, energies and behaviour of defects in irradiated graphitic carbon materials. Defect production due to high-energy nuclear radiations experienced in graphite moderators is generally associated with undesirable changes in internal energy, microstructure and physical properties—the so-called Wigner effect. On the flip side, the controlled introduction and ability to handle such defects in the electron beam is considered a desirable way to engineer the properties of carbon nanostructures. In both cases, the atomic-level details of structure and interaction are only just beginning to be understood. Here, using a model system of crystalline graphite, we show from first-principles calculations, new details in the behaviour of vacancy and interstitial defects. We identify a prominent barrier-state to energy release, reveal a surprising ability of vacancy defects to bridge the widely spaced atomic layers, and discuss physical property and microstructure changes during irradiation, including interactions with dislocations.