ACTA

Structural, Elastic, and Electronic Properties of Superhard Monoclinic C₃₂ under High Pressure

Xinchao Yang^a, Qun Wei^a, Bing Wei^a, Haiyan Yan^b, Ruike Yang^a, Meiguang Zhang^c, Qinghua Chen^d, Xinming Wang^a, Ronghui Yao^a, Chenyang Zhao^e, Chunying Ding^a
^aSchool of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, PR China
^bDepartment of Chemistry and Chemical Engineering, Baoji University of Arts and Sciences, Baoji 721013, PR China
^cCollege of Physics and Optoelectronic Technology, Nonlinear Research Institute, Baoji University of Arts and Sciences, Baoji 721016, PR China
^dSchool of Systems Science, Beijing Normal University, Beijing 100875, PR China
^eSchool of Microelectronics, Xidian University, Xi'an 710071, PR China

Received: June 11, 2019; revised version August 25, 2019; in final form September 3, 2019

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The properties of a recently proposed carbon allotrope of monoclinic C₃₂, which is named C2/m-32 carbon, were studied by first-principles calculations. This new carbon allotrope has an all-sp³ hybridized bonding network. The dynamic and mechanical stabilities at 0 GPa and 100 GPa are demonstrated by phonon dispersion and elastic constants, respectively. Studies of the elastic anisotropy of C2/m-32 carbon show that the elastic anisotropy increases with the augment of pressure. Surprisingly, the Vickers hardness of this new carbon allotrope is 90.9 GPa, which is almost as hard as diamond. The analysis of electronic band structure shows that C2/m-32 carbon is an indirect band gap semiconductor with a band gap of 4.18 eV. These results broaden our understanding of the structural and electronic properties of carbon allotropes.

DOI:10.12693/APhysPolA.136.940
topics: first-principles calculations, elastic anisotropy, electronic properties, superhard materials