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碳原子在石墨的同一平面内以六角晶格周期结构形式存在,在两种不同取向的石墨晶界处,会有五元环和七元环缺陷存在。这种缺陷会改变材料的电学,热学和力学等性质,研究这种缺陷结构对更深刻的理解sp2杂化低维碳材料的形成过程和可能应用有着十分重要的意义。本文通过扫描隧道显微镜观测高定向热解石墨表面发现,晶界的结构和形貌与晶界两侧晶粒的取向夹角密切相关。实验中观测到了对称和非对称的两种不同结构的晶界,分别对应了五元环-七元环缺陷对在晶界中的不同排列和取向。
Carbon atoms exist in the hexagonal lattice structure in the same plane of graphite, and there are five-membered and seven-membered ring defects in the graphite boundaries of two different orientations. Such defects will change the electrical, thermal and mechanical properties of the material. Studying this defect structure is of great significance to the deeper understanding of the formation process and possible application of sp2 hybrid low-dimensional carbon materials. In this paper, we observed the surface of highly oriented pyrolytic graphite by scanning tunneling microscope and found that the structure and morphology of the grain boundaries are closely related to the orientation angle of the grains on both sides of the grain boundaries. In the experiment, the grain boundaries of two different structures of symmetry and asymmetry were observed, corresponding to the different arrangement and orientation of the five-membered ring-seven-membered ring in the grain boundaries respectively.