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arXiv 1412.1982cond-mat.mtrl-scicond-mat.mes-hall
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石墨晶体-非晶结构转变时局域原子排列的拓扑特征

Topological characteristics of local atomic arrangements at crystalline-amorphous structural transition in graphite

A. D. Rud, I. M. Kirian, A. M. Lakhnik

摘要:

在球磨过程中,石墨发生了从晶态到非晶态的准连续结构转变。结合X射线衍射分析、反向蒙特卡罗模拟和Voronoi图方法,确定了碳纳米材料结构中短程有序和中程有序的定量特征。高分辨率TEM图像揭示了具有洋葱状结构的球状碳材料的形成。为模拟球磨石墨的原子构型而构造的Voronoi多面体(VP)在拓扑和度量特征上具有非常大的多样性,并且包含大量的5-fold面。通过对VP球度系数Ksph的分析,得出了球磨后碳的结构由石墨状向类金刚石状转变的局部原子排列变化的结论。提出将球度系数作为拓扑有序度的一个参数来定量估计非晶结构的无序度。

英文摘要:

Quasi-continuous structural transformation from the crystalline to amorphous state takes place in graphite during ball-milling. The quantitative characteristics of a short- and a medium-range orders in carbon nanomaterials structure are determined by a combined application of X-ray diffraction analysis, reverse Monte Carlo modeling and Voronoi diagram method. High resolution TEM images revealed formation of globular carbon materials having onion-like structure. The Voronoi polyhedra (VP) constructed for simulated atomic configurations of the ball-milled graphite have an extraordinary variety in their topological and metric characteristics and contain a lot of 5-fold faces. The analysis of VP sphericity coefficient Ksph enables a conclusion about the change of the local atomic arrangement in a structure of ball-milled carbon from graphite- to diamond-like. The sphericity coefficient is proposed to be as a parameter of the topological order to quantitative estimation of disordering degree in amorphous structures.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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