A Reinvestigation of a Superhard Tetragonal sp³ Carbon Allotrope.

Mengjiang Xing,Binhua Li,Qi Chen,Zhengtao Yu

doi:10.3390/ma9060484

Mengjiang Xing, Binhua Li + Show 2 more

Open Access

https://doi.org/10.3390/ma9060484

Copy DOI

Journal: Materials	Publication Date: Jun 17, 2016
Citations: 79	License type: CC BY 4.0

Affiliation: Kunming University of Science and Technology

Abstract

–carbon was first proposed by Zhang et al., this paper will report regarding this phase of carbon. The present paper reports the structural and elastic properties of the three-dimensional carbon allotrope –carbon using first-principles density functional theory. The related enthalpy, elastic constants, and phonon spectra confirm that the newly-predicted –carbon is thermodynamically, mechanically, and dynamically stable. The calculated mechanical properties indicate that –carbon has a larger bulk modulus (393 GPa), shear modulus (421 GPa), Young’s modulus (931 GPa), and hardness (55.5 GPa), all of which are all slightly larger than those of c-BN. The present results indicate that –carbon is a superhard material and an indirect-band-gap semiconductor. Moreover, –carbon shows a smaller elastic anisotropy in its linear bulk modulus, shear anisotropic factors, universal anisotropic index, and Young’s modulus.

Highlights

IntroductionThe group 14 elements, such as carbon, silicon, and germanium, have attracted much interest and have been extensively studied [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
Some scholars of great research found several carbon allotropes with low-energy metastable structures, such as monoclinic M-carbon [1,2], F-carbon [3], orthorhombic W-carbon [4], Z-carbon [5], H-carbon and S-carbon [6], C-carbon [7], Imma-carbon [8,9], M585-carbon [10], T12-carbon [11], C2/m-16 carbon [12], P2221 -carbon [13], and Cco-carbon [14]. We found that these carbon allotropes, with low-energy metastable structures with sp3 hybridization, could possibly explain the superhard property of materials
In conclusion, the low-energy metastable structures of I4–carbon have been systematically investigated based on the density functional theory

Summary

Introduction

The group 14 elements, such as carbon, silicon, and germanium, have attracted much interest and have been extensively studied [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]. The quest for carbon materials with desired properties is of great interest in both fundamental science and advanced technology. Some scholars of great research found several carbon allotropes with low-energy metastable structures, such as monoclinic M-carbon [1,2], F-carbon [3], orthorhombic W-carbon [4], Z-carbon [5], H-carbon and S-carbon [6], C-carbon [7], Imma-carbon [8,9], M585-carbon [10], T12-carbon [11], C2/m-16 carbon [12], P2221 -carbon [13], and Cco-carbon [14]. We found that these carbon allotropes, with low-energy metastable structures with sp hybridization, could possibly explain the superhard property of materials.

Methods

Results

Conclusion