Deconfinement leads to changes in the nanoscale plasticity of silicon
Deconfinement leads to changes in the nanoscale plasticity of silicon
复制标题
去细化导致硅的纳米级可塑性发生变化
DOI：
10.1038/nnano.2011.118
复制
发表时间：
2011-08-01
影响因子：
38.3
通讯作者：
Nowak, Roman
中科院分区：
文献类型：
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作者：
Chrobak, Dariusz;Tymiak, Natalia;Nowak, Roman
硅晶体在电子工业中扮演着重要的角色，硅纳米粒子在纳米机电系统、光子学和生物技术(1，2)等领域都有应用。然而，在硅中观察到的弹塑性转变还没有被完全理解，尤其是硅的可塑性是由位错还是由相之间的转变决定的，还不清楚。在这里，基于压缩实验和分子动力学模拟，我们发现体硅(3-6)和硅纳米颗粒的力学性能有明显的不同。我们发现，体硅处于相对约束状态，其塑性由相变控制，而纳米硅的约束较小，表现出位错驱动的塑性。这种转变，我们称之为退禁闭，也可以解释在变形的硅纳米边(7，8)中没有相变的原因。此外，这一现象与在形状记忆合金纳米柱中观察到的效应一致(9)，并提供了对早期塑性的起源的洞察(10-19)。
Silicon crystals have an important role in the electronics industry, and silicon nanoparticles have applications in areas such as nanoelectromechanical systems, photonics and biotechnology(1,2). However, the elastic-plastic transition observed in silicon is not fully understood; in particular, it is not known if the plasticity of silicon is determined by dislocations or by transformations between phases. Here, based on compression experiments and molecular dynamics simulations, we show that the mechanical properties of bulk silicon(3-6) and silicon nanoparticles are significantly different. We find that bulk silicon exists in a state of relative constraint, with its plasticity dominated by phase transformations, whereas silicon nanoparticles are less constrained and display dislocation-driven plasticity. This transition, which we call deconfinement, can also explain the absence of phase transformations in deformed silicon nanowedges(7,8). Furthermore, the phenomenon is in agreement with effects observed in shape-memory alloy nanopillars(9), and provides insight into the origin of incipient plasticity(10-19).