在冷压缩下sp3混合碳的多态相
1Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
Journal of the American Chemical Society
|April 12, 2012
概括
研究人员通过计算探索冷压缩石墨,发现了新的超硬碳结构. 这些新的sp(3) 混合碳全属体表现出高硬度和光学透明度,可能解释实验发现.
科学领域:
- 材料科学 材料科学 材料科学
- 固态物理 固态物理
- 计算化学的计算化学
背景情况:
- 在冷压缩下,石墨转化为超硬的碳.
- 这些超硬碳的精确结构在实验上仍未确定.
研究的目的:
- 为了对碳的高压晶体相进行广泛的结构性搜索.
- 为了分类和描述新预测的sp(3) 混合碳结构.
主要方法:
- 利用进化算法进行无偏的结构性搜索.
- 用密度函数理论计算来进行能量和属性分析.
- 模拟的X射线衍射 (XRD) 光谱,用于与实验数据进行比较.
主要成果:
- 确定了九个低能量的,sp(3) 混合碳多态结构.
- 基于曲石墨烯层堆叠安排的结构分类.
- 七个新的结构比Cco-C(8) (Z-碳) 在0-25GPa之间更稳定.
- 几个预测的结构显示弹性模块和硬度相当于立方钻石.
- Z-碳-4表现出最高的预测硬度 (93.4).
- 大多数结构都是光学透明的.
- 模拟的XRD光谱与冷压缩石墨的实验数据保持一致.
结论:
- 该分类方案为新型sp(3) 混合碳异构物提供了设计策略.
- 新预测的结构在能源上是有利的,并且具有理想的机械性能.
- 冷压缩石墨的实验样本可能含有多重多态相的sp(3) 混合碳.
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