Prediction of a Three-Dimensional Conductive Superhard Material: Diamond-like BC2

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• 作者：Lifang Xu ; Zhisheng Zhao ; Li-Min Wang ; Bo Xu ; Julong He ; Zhongyuan Liu ; Yongjun Tian
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：December 30, 2010
• 年：2010
• 卷：114
• 期：51
• 页码：22688-22690
• 全文大小：188K
• 年卷期：v.114,no.51(December 30, 2010)
• ISSN：1932-7455

文摘

A tetragonal BC₂ (t-BC₂) phase originating from the cubic diamond structure was predicted by first-principles calculations. The t-BC₂ structure has a tetragonal lattice (space group I4₁/amd, No. 141) and possesses the simple stacking sequence BC₂BC₂... along its c axis. The structural stability of the proposed t-BC₂ was confirmed by calculations of the elastic constants and phonon frequencies. The electronic densities of states of t-BC₂ show that all the B−C and C−C bonds in the crystal are metallic. Thus, t-BC₂ possesses three-dimensional conductivity, which is different from the two-dimensional conductivity of the diamond-like t-BC₃. The theoretical Vickers hardness of t-BC₂ is 56.0 GPa, which is close to that of cubic boron nitride. The B/G ratio of t-BC₂ is 1.09, which is larger than that of diamond (0.83), indicating that the t-BC₂ phase is more ductile than diamond.