Mechanism for the Amorphisation of Diamond
Mechanism for the Amorphisation of Diamond
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DOI：
10.1002/adma.201104511
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发表时间：
2012-04-17
影响因子：
29.4
通讯作者：
Prawer, Steven
中科院分区：
文献类型：
--
作者：
Fairchild, Barbara A.;Rubanov, Sergey;Prawer, Steven
金刚石是具有极端特性的材料的典型例子。例如，金刚石的导热系数、杨氏模量、硬度和原子密度是所有已知材料中最高的，并被广泛应用于各种应用，[1-4]包括，最近，作为新生量子信息产业的重要推动者尽管钻石具有理想的性质，但人们对它的性质仍有许多不了解的地方。特别是，由于没有比金刚石更硬的材料可以与之比较，因此很难在其机械强度的极限下精确测量金刚石的性能。因此，测量金刚石的机械强度往往不像测量其他材料那样直接。例如，激光冲击压缩金刚石[6]的结果和金刚石的非晶化作为磨损[7]的机制，并不能直接显示纯拉伸环境下金刚石晶格的破坏。这些关于金刚石分解的知识对于计算基准测试以及实际设备设计都很重要。本文利用离子束引起的晶格膨胀引起金刚石的非晶化，研究了金刚石的抗拉强度。电子能量损失光谱（EELS）用于探测局部原子密度。这允许定义独立于物质[8]（SRIM）建模中的停止范围的非晶化阈值。结果表明，当密度降低到< 2.95 g·cm−3时，金刚石晶格坍塌为非晶态。分子动力学模拟证实，在这个临界密度以下，弛豫态确实是无定形的。注入钻石的MeV轻离子穿透材料，通过电子制动失去能量，直到核停止开始占主导地位，晶格原子被移出，导致空缺和撞击。[8,9]这就产生了埋藏的损伤
Diamond is a textbook example of a material with extreme properties. For example, diamond displays the highest thermal conductivity, Young’s modulus, hardness, and atomic density of any known material and is widely used in a variety of applications,[1–4] including, most recently, as a vital enabler of the nascent quantum information industry.[5] Despite diamond’s ideal nature, there is much that is not understood concerning its properties. In particular, it has been difficult to accurately measure the properties of diamond at the limits of its mechanical strength, as there are no materials harder than it to compare with. Measurements of the mechanical strength of diamond therefore tend to be less direct than for other materials. For example, laser shock compression results for diamond [6] and the amorphisation of diamond as a mechanism for wear [7] do not directly show the breakdown of the diamond lattice in a pure tensile environment. Such knowledge of the breakdown of diamond is important for computational benchmarking as well as practical device design.Here we investigate the tensile strength of diamond by exploiting the ion beam induced swelling of the lattice to cause amorphisation of diamond. Electron Energy Loss Spectroscopy (EELS) is used to probe the local atomic density. This allows for a definition of the threshold for amorphisation that is independent of Stopping Range in Matter [8](SRIM) modeling. The results show that when the density is reduced to a value< 2.95 g· cm− 3 the diamond lattice collapses to an amorphous state. Molecular dynamics simulations confirm that below this critical density, the relaxed state is indeed amorphous. Light MeV ions implanted into diamond penetrate the material, losing energy by electronic braking until nuclear stopping begins to dominate and lattice atoms are dislodged, resulting in vacancies and knock-ons.[8, 9] This gives rise to a buried damaged