College of Materials Science and Engineering and Key Laboratory of Automobile Materials of MOE, Jilin University, Changchun 130012, People's Republic of China.
J Phys Condens Matter. 2013 Oct 23;25(42):425502. doi: 10.1088/0953-8984/25/42/425502. Epub 2013 Sep 27.
With first-principle calculations, we studied the structural stability and electronic properties of the BxCy compounds based on three kinds of phases including diamond-like, C20-like and B15-like phases. The C20-like structure B8C12 is found to be a new stable structure with relatively low formation energy in middle boron concentration and is expected to be synthesized experimentally. Combined with a microscopic model, the Vickers hardness of the different configurations of BxCy compounds is analyzed with the change of boron concentration. It is found that the hardness of the B-C system has a decreasing trend with the increase of boron concentration. In addition, all the structures have metallic properties, except B12C3 and B14C. With the analysis of Mulliken bond population and charge distribution, the bonds with high electron density and short bond length have an important contribution to the hardness in the B-C system, while the effect of metallicity to hardness can be ignored.
我们通过第一性原理计算，研究了基于金刚石相、C20 相和 B15 相等三种相的 BxCy 化合物的结构稳定性和电子性质。发现 C20 相结构 B8C12 是一种在中等硼浓度下具有较低形成能的新稳定结构，有望在实验中合成。结合微观模型，分析了不同硼浓度下 BxCy 化合物不同构型的维氏硬度。发现随着硼浓度的增加，B-C 体系的硬度呈下降趋势。此外，除了 B12C3 和 B14C，所有结构都具有金属性质。通过对 Mulliken 键布居数和电荷分布的分析，发现具有高电子密度和短键长的键对 B-C 体系的硬度有重要贡献，而金属性对硬度的影响可以忽略不计。
