The nature of strength enhancement and weakening by pentagon-heptagon defects in graphene
The nature of strength enhancement and weakening by pentagon-heptagon defects in graphene
复制标题
石墨烯中五边形-七边形缺陷增强和减弱强度的本质
DOI：
10.1038/nmat3370
复制
发表时间：
2012-09-01
期刊：
影响因子：
41.2
通讯作者：
Dresselhaus, Mildred
中科院分区：
文献类型：
--
作者：
Wei, Yujie;Wu, Jiangtao;Dresselhaus, Mildred
石墨烯中的二维晶体结构对现有理论的适用性提出了挑战，这些理论已经被用来表征其三维对应结构。在重要的二维晶体中建立可靠的结构-性质关系是充分利用其优异性能的关键。随着大面积多晶石墨烯(1-5)的成功合成，了解石墨烯(2-4)中的晶界(GB)如何改变其物理性质(5-13)具有重要的科学和技术意义。最近的一项研究表明，更多的GB缺陷可以直观地产生更高的倾斜GB强度(参考文献2)。10)。我们在这里表明，GB强度可以随着倾角的增加而增加，也可以随着倾角的增加而减少，这种行为可以用连续介质力学很好地解释。影响力学性能的不仅仅是缺陷的密度，缺陷的详细排列也很重要。如果五边形-七面体缺陷均匀分布，倾斜金字塔的强度随着倾斜角的平方而增加，而在其他情况下，这种趋势被打破。我们发现，机械破坏总是从六边形-七角环的共键开始的。我们目前的工作为理解缺陷如何在二维晶体中相互作用提供了基本指导，这对于将高强度和可拉伸的石墨烯(14)用于生物和电子应用是重要的。
The two-dimensional crystalline structures in graphene challenge the applicability of existing theories that have been used for characterizing its three-dimensional counterparts. It is crucial to establish reliable structure-property relationships in the important two-dimensional crystals to fully use their remarkable properties. With the success in synthesizing large-area polycrystalline graphene(1-5), understanding how grain boundaries (GBs) in graphene(2-4) alter its physical properties(5-13) is of both scientific and technological importance. A recent work showed that more GB defects could counter intuitively give rise to higher strength in tilt GBs (ref. 10). We show here that GB strength can either increase or decrease with the tilt, and the behaviour can be explained well by continuum mechanics. It is not just the density of defects that affects the mechanical properties, but the detailed arrangements of defects are also important. The strengths of tilt GBs increase as the square of the tilt angles if pentagon-heptagon defects are evenly spaced, and the trend breaks down in other cases. We find that mechanical failure always starts from the bond shared by hexagon-heptagon rings. Our present work provides fundamental guidance towards understanding how defects interact in two-dimensional crystals, which is important for using high-strength and stretchable graphene(14) for biological and electronic applications.