Cheng Jiao, Zhang Qidong
Xi'an University of Architecture and Technology, Xi'an 710055, China.
School of Microelectronics, Xidian University, Xi'an 710071, China.
Materials (Basel). 2020 May 1;13(9):2079. doi: 10.3390/ma13092079.
Based on first-principle calculations, the mechanical anisotropy and the electronic and optical properties of seven kinds of carbon materials are investigated in this work. These seven materials have similar structures: they all have X-type structures, with carbon atoms or carbon clusters at the center and stacking towards the space. A calculation of anisotropy shows that the order of elastic anisotropy in terms of the shear modulus, Young's modulus and Poisson's ratio of these seven carbon materials with similar structure is diamond < supercubane < T carbon < Y carbon < TY carbon < cubane-diyne < cubane-yne. As these seven carbon materials exhibit cubic symmetry, Young's modulus has the same anisotropy in some major planes, so the order of elastic anisotropy in the Young's modulus of these seven main planes is (111) plane < (001) plane = (010) plane = (100) plane < (011) plane = (110) plane = (101) plane. It is also due to the fact that their crystal structure has cubic symmetry that the elastic anisotropy in the shear modulus and the Poisson's ratio of these seven carbon materials on the seven major planes are the same. Among the three propagation directions of [100], [110], and [111], the [110] propagation direction's anisotropic ratio of the sound velocity of TY carbon is the largest, while the anisotropic ratio of the sound velocity of cubane-diyne on the [100] propagation direction is the smallest. In addition, not surprisingly, the diamond has the largest Debye temperature, while the TY carbon has the smallest Debye temperature. Finally, TY carbon, T carbon and cubane-diyne are also potential semiconductor materials for photoelectric applications owing to their higher or similar absorption coefficients to GaAs in the visible region.
基于第一性原理计算，本文研究了七种碳材料的力学各向异性以及电子和光学性质。这七种材料具有相似的结构：它们都具有X型结构，中心为碳原子或碳簇，并向空间堆叠。各向异性计算表明，这七种结构相似的碳材料在剪切模量、杨氏模量和泊松比方面的弹性各向异性顺序为：金刚石＜超立方烷＜T碳＜Y碳＜TY碳＜立方二炔＜立方炔。由于这七种碳材料具有立方对称性，杨氏模量在一些主平面上具有相同的各向异性，因此这七个主平面的杨氏模量弹性各向异性顺序为：(111)面＜(001)面 = (010)面 = (100)面＜(011)面 = (110)面 = (101)面。同样由于它们的晶体结构具有立方对称性，这七种碳材料在七个主平面上的剪切模量和泊松比的弹性各向异性是相同的。在[100]、[110]和[111]这三个传播方向中，TY碳在[110]传播方向上的声速各向异性比最大，而立方二炔在[100]传播方向上的声速各向异性比最小。此外，不出所料，金刚石具有最高的德拜温度，而TY碳具有最低的德拜温度。最后，TY碳、T碳和立方二炔由于在可见光区域对砷化镓具有较高或相似的吸收系数，也是光电应用的潜在半导体材料。
