Superhard superstrong carbon clathrate

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• 作者：Zihe Li¹ ; Meng Hu¹ ; Mengdong Ma ; Yufei Gao ; Bo Xu ; Julong He ; Dongli Yu ; Yongjun Tian ; Zhisheng Zhao ; ^{zzhao@ysu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 刊名：Carbon
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：105
• 期：Complete
• 页码：151-155
• 全文大小：1398 K

文摘

Carbon clathrate is a kind of typical carbon allotrope that has an open framework composed of various types of cages, displaying intriguing electronic and mechanical properties. This paper proposes a superhard superstrong carbon clathrate via first-principle calculations. This carbon clathrate, called C₆₀ clathrate, contains 60 carbon atoms buckled through sp³-hybridized bonds in a cubic unit cell with symmetry of Im-3m, and possesses the network topology of commonly called binodal net. C₆₀ clathrate is energetically more stable than fullerene C₆₀ at ambient pressure, and it is more favorable than graphite at a pressure above 50.1 GPa C₆₀ clathrate can be constructed by small C₂₄ cage and flat C₁₈ drum. It shows a high density of 3.34 g/cm³, which is the densest carbon clathrate to date. The estimated Vickers hardness, tensile strength, and shear strength of C₆₀ clathrate reach remarkably high values of 82.8, 90.7, and 76.4 GPa, respectively, indicating its superhard and superstrong characteristic. Band structure calculations indicate that C₆₀ clathrate is semiconductive with a direct band gap of 2.26 eV. C₆₀ clathrate can be potentially used in photovoltaic devices.