A Revisited Mechanism of the Graphite-to-Diamond Transition at High Temperature
A Revisited Mechanism of the Graphite-to-Diamond Transition at High Temperature
复制标题
重新审视高温下石墨向金刚石转变的机制
DOI：
10.1016/j.matt.2020.05.013
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发表时间：
2020-09-02
期刊：
影响因子：
18.9
通讯作者：
Zhu, Qiang
中科院分区：
文献类型：
--
作者：
Zhu, Sheng-cai;Yan, Xiao-zhi;Zhu, Qiang
高温高压下的石墨-金刚石转变一直是物理科学的中心课题。然而，它的原子机制仍然存在争议。采用大规模分子动力学（MD）模拟，我们报告了一种机制，即石墨基质中的金刚石核在两个优选方向上传播，其中石墨[ 120]比[001]快约2.5倍。因此，立方金刚石（CD）是动力学上有利的产物，而只有少数六方金刚石（HD）可以作为CD的孪晶存在。在分子动力学模拟中观察到的t-（100）gr//（11-1）cd + [010]gr//[1-10]cd共格界面被我们的高分辨透射电镜实验所证实。提出的机制不仅阐明了HD在石墨-金刚石转变中的作用，而且通过微观结构工程对强化合成金刚石产生了原子上的见解。
The graphite-diamond transition, under high-pressure and high-temperature conditions, has been a central subject in physical science. However, its atomistic mechanism remains under debate. Employing large-scale molecular dynamics (MD) simulations, we report a mechanism whereby the diamond nuclei in the graphite matrix propagate in two preferred directions, among which the graphite [ 120] is about 2.5 times faster than [001]. Consequently, cubic diamond (CD) is the kinetically favorable product, while only a few hexagonal diamonds (HDs) can exist as the twins of CDs. The coherent interface of t-(100)gr//(11-1)cd + [010]gr//[1-10]cd observed in MD simulation was confirmed by our high-resolution transmission electron microscopy experiment. The proposed mechanism not only clarifies the role of HD in graphite-diamond transition but also yields atomistic insight into strengthening synthetic diamond via microstructure engineering.