钻石
石墨
材料科学
金刚石材料性能
菱形
化学物理
金刚石立方
碳纤维
相变
微观结构
晶体孪晶
结晶学
纳米技术
凝聚态物理
复合材料
化学
物理
复合数
作者
Shengcai Zhu,Xiaozhi Yan,Jin Liu,Artem R. Oganov,Qiang Zhu
出处
期刊:Matter
[Elsevier]
日期:2020-09-01
卷期号:3 (3): 864-878
被引量:28
标识
DOI:10.1016/j.matt.2020.05.013
摘要
Graphite and diamond are two well-known allotropes of carbon with distinct physical properties due to different atomic connectivity. Graphite has a layered structure in which the honeycomb carbon sheets can easily glide, while atoms in diamond are strongly bonded in all three dimensions. The transition from graphite to diamond has been a central subject in physical science. One way to turn graphite into diamond is to apply the high pressure and high temperature (HPHT) conditions. However, atomistic mechanism of this transition is still under debate. From a series of large-scale molecular dynamics (MD) simulations, we report a mechanism that the diamond nuclei originate at the graphite grain boundaries and propagate in two preferred directions. In addition to the widely accepted [001] direction, we found that the growth along [120] direction of graphite is even faster. In this scenario, cubic diamond (CD) is the kinetically favorable product, while hexagonal diamond (HD) would appear as minor amounts of twinning structures in two main directions. Following the crystallographic orientation relationship, the coherent interface t-(100)gr//(11-1)cd + [010]gr//[1-10]cd was also confirmed by high-resolution transmission electron microscopy (HR-TEM) experiment. The proposed phase transition mechanism does not only reconcile the longstanding debate regarding the role of HD in graphite-diamond transition, but also yields the atomistic insight into microstructure engineering via controlled solid phase transition.
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