文章基本信息

标题：Influences of carbon concentration on crystal structures and ideal strengths of B2CxO compounds in the B-C-O system
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作者：Meiguang Zhang ; Haiyan Yan ; Baobing Zheng 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
期号：1
DOI：10.1038/srep15481
语种：English
出版社：Springer Nature
摘要：The search for novel superhard materials with special structures and improved thermal stability and hardness remains considerably experimental and theoretical challenges. Recent reports proposed that higher carbon content in ternary B₂C_xO compounds, which are isoelectronic with diamond, would lead to increased strength and hardness. This notion was derived from the calculated elastic parameters and empirical hardness formulas based on structural and electronic properties of the equilibrium structures. In present work, we introduce three potential ultra-incompressible and thermodynamically stable B₂C_xO ( x ≥ 2) phases via a systematic particle swarm optimization algorithm structure searches. By evaluating the trends of the crystal configuration, electronic structure, and mechanical properties as a function of the C concentration, it is found that the high carbon concentration benefits the formation of the sp ³ C-C covalent bonds and leads to the enhanced elastic moduli and ideal strengths in these B₂C_xO compounds. Studies of strain-stress behavior at large deformation, however, indicate that all these B₂C_xO compounds possess substantially lower ideal shear strengths than those of diamond and c -BN, suggesting that they may not be intrinsically superhard.