Structural, Elastic, and Electronic Properties of Superhard Monoclinic C32 under High Pressure
Xinchao Yanga, Qun Weia, Bing Weia, Haiyan Yanb, Ruike Yanga, Meiguang Zhangc, Qinghua Chend, Xinming Wanga, Ronghui Yaoa, Chenyang Zhaoe, Chunying Dinga
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