磷分子中的高度游动原子空位
Highly Itinerant Atomic Vacancies in Phosphorene
摘要：
利用详细的第一性原理计算，我们研究了磷烯中空位的跳跃率，磷烯是一种除了石墨烯之外的新兴二维材料。我们的工作预测，这些单空位（MV），表现出高度流动性和各向异性运动的直接观察，只有在约70 K或更低的温度下，热活动被大大抑制是可能的。在室温下，由于0.3eV的低扩散势垒，MV的运动比石墨烯中的运动快16个数量级。与空位相关的内建应变沿Z字形方向延伸很远，而沿扶手椅方向迅速衰减。我们揭示了磷烯中双空位（DV）通过多重解离-复合过程运动的新特征，这是由于DV分裂成两个MV的能量消耗很小，约为1.05 eV。此外，我们还发现，沿Z字形方向的单轴拉伸应变可以促进运动涡的运动，而沿扶手椅方向的拉伸应变则相反。这些巡回功能的空缺，植根于独特的puckering结构，促进债券重组，使磷烯是一个光明的新的机会，以扩大知识的演变的空缺，和一个适当的控制异常活跃和各向异性运动的空缺应是基于磷烯的应用程序的关键。
英文摘要：
Using detailed first-principles calculations, we investigate the hopping rate of vacancies in phosphorene, an emerging elemental 2D material besides graphene. Our work predicts that a direct observation of these mono-vacancies (MVs), showing a highly mobile and anisotropic motion, is possible only at low temperatures around 70 K or below where the thermal activity is greatly suppressed. At room temperature, the motion of a MV is sixteen orders faster than that in graphene, because of the low diffusion barrier of 0.3 eV. Built-in strain associated with the vacancies extends far along the zigzag direction while attenuating rapidly along the armchair direction. We reveal new features of the motion of di-vacancies (DVs) in phosphorene via multiple dissociation-recombination processes of vacancies owing to a small energy cost of ~ 1.05 eV for the splitting of a DV into two MVs. Furthermore, we find that uniaxial tensile strain along the zigzag direction can promote the motion of MVs, while the tensile strain along the armchair direction has the opposite effect. These itinerant features of vacancies, rooted in the unique puckering structure facilitating bond reorganization, enable phosphorene to be a bright new opportunity to broaden the knowledge of the evolution of vacancies, and a proper control of the exceedingly active and anisotropic movement of the vacancies should be critical for applications based on phosphorene.
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