标题： 石墨烯中的线缺陷：掺杂如何影响电子和机械性能 显示英文标题

标题： Line defects in Graphene: How doping affects the electronic and mechanical properties

摘要： 石墨烯和碳纳米管具有卓越的机械和电子性能。 固有的线缺陷，如局部非六边形重构或晶界，会显著降低抗拉强度，但具有令人兴奋的电子特性。 在此，我们从第一性原理出发，基于全势密度泛函理论的水平研究石墨烯中线缺陷的性质，并评估掺杂作为一种增强此类材料的策略。 我们通过将虚拟晶体近似的结果与局部化学物种替换的结果进行比较，仔细区分掺杂的全局和局部效应，以深入了解断裂和稳定机制。 我们发现，n型掺杂或用氮进行局部替换可显著提高极限抗拉强度。 特别是，它可以在超过原始材料极限抗拉强度的情况下稳定缺陷。 因此，我们将此视为增强石墨烯材料的关键策略。 此外，我们发现掺杂和/或施加外部应力会导致可调节且具有技术兴趣的金属/半导体转变。 显示英文摘要

摘要： Graphene and carbon nanotubes have extraordinary mechanical and electronic properties. Intrinsic line defects such as local non-hexagonal reconstructions or grain boundaries, however, significantly reduce the tensile strength, but feature exciting electronic properties. Here, we address the properties of line defects in graphene from first-principles on the level of full-potential density-functional theory, and assess doping as one strategy to strengthen such materials. We carefully disentangle the global and local effect of doping by comparing results from the virtual crystal approximation with those from local substitution of chemical species, in order to gain a detailed understanding of the breaking and stabilization mechanisms. We find that n-type doping or local substitution with nitrogen increases the ultimate tensile strength significantly. In particular, it can stabilize the defects beyond the ultimate tensile strength of the pristine material. We therefore propose this as a key strategy to strengthen graphenic materials. Furthermore, we find that doping and/or applying external stress lead to tunable and technologically interesting metal/semi-conductor transitions.