Exotic Cubic Carbon Allotropes

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• 作者：Meng Hu ; Fei Tian ; Zhisheng Zhao ; Quan Huang ; Bo Xu ; Li-Min Wang ; Hui-Tian Wang ; Yongjun Tian ; Julong He
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：November 15, 2012
• 年：2012
• 卷：116
• 期：45
• 页码：24233-24238
• 全文大小：401K
• 年卷期：v.116,no.45(November 15, 2012)
• ISSN：1932-7455

文摘

Elemental carbon exists in various aesthetically pleasing architectures. These forms include a group of synthesized allotropes with cubic modifications that have taken controversial or even unidentified crystal structures, which makes determining their physical properties difficult. In this study, four novel cubic carbon polymorphs (fcc-C₁₀, fcc-C₁₂, bcc-C₂₀, and fcc-C₃₂) that exhibit lattice parameters within the same range as those of undetermined cubic carbon allotropes are proposed by employing a newly developed ab initio particle-swarm optimization methodology for crystal structure prediction. The four structures are all three-dimensional polymers consisting of unique, small C₁₀, C₁₂, C₂₀, and C₃₂ cages with quite low density. Investigation of their electronic and mechanical properties illustrate that the cage-like cubic carbons are all semiconductors with excellent mechanical performance, specifically superhardness and high ductility. Moreover, we readily explain a long-standing controversial experimentally synthesized cubic carbon (viz., the so-called 鈥渟uperdense鈥?carbon) using the previously proposed bcc C₆ based on the coincident lattice constant and electron diffraction data between the theoretical and experimental results.