Fujii Yasumaru, Maruyama Mina, Cuong Nguyen Thanh, Okada Susumu
Department of Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan.
Phys Rev Lett. 2020 Jul 3;125(1):016001. doi: 10.1103/PhysRevLett.125.016001.
A pentagonal covalent network consisting of sp^{2} and sp^{3} C atoms has been investigated based on the density functional theory. Our theoretical investigations clarified that the pentagonal covalent network is a metastable three-dimensional carbon allotrope with the Fm3[over ¯]m space group possessing remarkable mechanical properties: relatively high bulk modulus of 381 GPa together with a negative Poisson's ratio of -0.241. Accordingly, the pentagonal covalent network possesses extremely high Young's and shear moduli of 1691 and 1113 GPa, respectively, surpassing those of the diamond. The electronic structure of the pentagonal network is a semiconductor with an indirect band gap of 2.52 eV between L and X points for valence and conduction band edges, respectively, with the relatively small carrier masses.
基于密度泛函理论，对由(sp^{2})和(sp^{3})碳原子组成的五角形共价网络进行了研究。我们的理论研究表明，五角形共价网络是一种亚稳态三维碳同素异形体，其空间群为(Fm3\overline{m})，具有显著的力学性能：相对较高的体模量为(381)吉帕，泊松比为(-0.241)。因此，五角形共价网络分别具有极高的杨氏模量和剪切模量，分别为(1691)吉帕和(1113)吉帕，超过了金刚石。五角形网络的电子结构是一种半导体，价带和导带边缘在(L)点和(X)点之间的间接带隙分别为(2.52)电子伏特，载流子质量相对较小。
