Crystal Structures, Stabilities, Electronic Properties, and Hardness of MoB2: First-Principles Calculations

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• 作者：Li-Ping Ding ; Peng Shao ; Fang-Hui Zhang ; Cheng Lu ; Lei Ding ; Shu Ya Ning ; Xiao Fen Huang
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：July 18, 2016
• 年：2016
• 卷：55
• 期：14
• 页码：7033-7040
• 全文大小：621K
• 年卷期：0
• ISSN：1520-510X

文摘

On the basis of the first-principles techniques, we perform the structure prediction for MoB₂. Accordingly, a new ground-state crystal structure WB₂ (P6₃/mmc, 2 fu/cell) is uncovered. The experimental synthesized rhombohedral R3̅m and hexagonal AlB₂, as well as theoretical predicted RuB₂ structures, are no longer the most favorite structures. By analyzing the elastic constants, formation enthalpies, and phonon dispersion, we find that the WB₂ phase is thermodynamically and mechanically stable. The high bulk modulus B, shear modulus G, low Poisson’s ratio ν, and small B/G ratio are benefit to its low compressibility. When the pressure is 10 GPa, a phase transition is observed between the WB₂-MoB₂ and the rhombohedral R3̅m MoB₂ phases. By analyzing the density of states and electron density, we find that the strong covalent is formed in MoB₂ compounds, which contributes a great deal to its low compressibility. Furthermore, the low compressibility is also correlated with the local buckled structure.