Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing, 100022, China.
Nano Lett. 2011 Jun 8;11(6):2382-5. doi: 10.1021/nl200735p. Epub 2011 May 5.
To safely and reliably use nanowires (NWs) for exploring new functions for different nanodevices, the mechanical properties and structural evolution of the nanowires under external stress become highly important. Large strain (up to 14%) bending experiments of Si NWs were conducted in a high-resolution transmission electron microscope at atomic resolution. The direct dynamic atomic-scale observations revealed that partial and full dislocation nucleation, motion, escape, and interaction were responsible for absorbing the ultralarge strain of up to 14% in bent Si nanowires. The prevalent full dislocation movement and interactions induced the formation of Lomer lock dislocations in the Si NWs. Finally, in contrast to the unlock process of Lomer dislocations that can happen in metallic materials, we revealed that the continuous straining on the Lomer dislocations induced a crystal-amorphous (c-a) transition in Si NWs. Our results provide direct explanation about the ultralarge straining ability of Si at the nanometer scale.
为了安全可靠地利用纳米线（NWs）探索不同纳米器件的新功能，纳米线在外力作用下的力学性能和结构演化变得非常重要。在高分辨率透射电子显微镜中，对 SiNWs 进行了高达 14%的大应变（高达 14%）弯曲实验，达到原子分辨率。直接的动态原子尺度观察表明，部分位错和全位错的形核、运动、逃逸和相互作用是吸收高达 14%的弯曲 Si 纳米线中超大应变的原因。普遍的全位错运动和相互作用导致 SiNWs 中形成 Lomer 锁位错。最后，与金属材料中可能发生的 Lomer 位错解锁过程不同，我们揭示了 Lomer 位错的连续应变导致 SiNWs 中发生晶体-非晶（c-a）转变。我们的结果提供了关于 Si 在纳米尺度下具有超拉伸能力的直接解释。
