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[資源]
最近發(fā)表在PRL的第一性原理文章:關于硬質(zhì)/超硬材料方面研究
最近剛剛看了一篇發(fā)表在PRL上的文章.文章通過第一性原理計算研究了過渡族金屬硼化物的熱力學,力學和動力學穩(wěn)定性問題和理想強度。對廣泛采用的硬度模型和以前提出的三維共價鍵強化機制提出了挑戰(zhàn)。
仔細讀過文章后,深有體會,特與各位蟲友分享。希望對正在搞第一性原理計算的各位蟲友有幫助。文章摘要如下:
Stability and Strength of Transition-Metal Tetraborides and Triborides
Using density functional theory, we show that the long-believed transition-metal tetraborides (TB4) of tungsten and molybdenum are in fact triborides (TB3). This finding is supported by thermodynamic, mechanical, and phonon instabilities of TB4, and it challenges the previously proposed origin of superhardness of these compounds and the predictability of the generally used hardness model. Theoretical calculations for the newly identified stable TB3 structure correctly reproduce their structural and mechanical properties, as well as the experimental x-ray diffraction pattern. However, the relatively low shear moduli and strengths suggest that TB3 cannot be intrinsically stronger than c-BN. The origin of the lattice instability of TB3 under large shear strain that occurs at the atomic level during plastic deformation can be attributed to valence charge depletion between boron and metal atoms, which enables easy sliding of boron layers between the metal ones. |
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- 附件 1 : PRL108,255502(2012).pdf
2012-06-23 10:46:34, 2.44 M
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