Hardness of T-carbon: Density functional theory calculations
Hardness of T-carbon: Density functional theory calculations
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T-碳的硬度：密度泛函理论计算
DOI：
10.1103/physrevb.84.121405
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发表时间：
2011-09-16
影响因子：
3.7
通讯作者：
Li, Yiyi
中科院分区：
文献类型：
--
作者：
Chen, Xing-Qiu;Niu, Haiyang;Li, Yiyi
我们重新考虑并解释了最近提出的碳的同素异形体，t -碳的力学性质[Sheng et al., Phys.]。应用密度泛函理论与不同的经验硬度模型相结合[j]。早期Gao等人的模型认为t -碳的维氏硬度高达61 GPa，与超硬立方氮化硼（c-BN）相当。与此相反，我们发现t -碳不是超硬材料，因为它的维氏硬度不超过10 GPa。除了为t -碳中不存在超硬度提供明确的证据外，我们还讨论了Gao等人以及Simunek和Vackar （SV）模型在预测t -碳硬度时失败的物理原因，原因在于他们对准sp(3)样C-C杂化的高度各向异性分布处理不当。基于超原子概念的Gao等和SV模型提出了一种可能的补救方法，它确实产生了约8 GPa的维氏硬度。
We reconsider and interpret the mechanical properties of the recently proposed allotrope of carbon, T-carbon [Sheng et al., Phys. Rev. Lett. 106, 155703 (2011)], using density functional theory in combination with different empirical hardness models. In contrast with the early estimation based on Gao et al.'s model, which attributes to T-carbon a high Vickers hardness of 61 GPa comparable to that of superhard cubic boron nitride (c-BN), we find that T-carbon is not a superhard material, since its Vickers hardness does not exceed 10 GPa. Besides providing clear evidence for the absence of superhardness in T-carbon, we discuss the physical reasons behind the failure of Gao et al.'s and Simunek and Vackar's (SV) models in predicting the hardness of T-carbon, residing in their improper treatment of the highly anisotropic distribution of quasi-sp(3)-like C-C hybrids. A possible remedy for the Gao et al. and SV models based on the concept of the superatom is suggested, which indeed yields a Vickers hardness of about 8 GPa.