Theoretical Investigation of the High-Pressure Structure, Phase Transition, and Mechanical and Electronic Properties of Mg3N2

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• 作者：Jian Li ; Changzeng Fan ; Xu Dong ; Ye Jin ; Julong He
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：May 15, 2014
• 年：2014
• 卷：118
• 期：19
• 页码：10238-10247
• 全文大小：868K
• 年卷期：v.118,no.19(May 15, 2014)
• ISSN：1932-7455

文摘

The potential structures of magnesium nitride with a chemical composition of Mg₃N₂ are examined by utilizing a widely adopted evolutionary methodology for crystal structure prediction. In addition to the previously proposed phases (伪-, 尾- and 纬-Mg₃N₂), we find five high-pressure phases for Mg₃N₂: (1) a Cmc21 symmetric structure (蔚-Mg₃N₂) at 27 GPa, (2) a R3c̅ symmetric structure (蟿-Mg₃N₂) at 30 GPa, (3) a Cmcm symmetric structure (蠅-Mg₃N₂) at 53 GPa, (4) a Ima2 symmetric structure (位-Mg₃N₂) at 68 GPa, and (5) a Ibam symmetric structure (渭-Mg₃N₂) at 115 GPa. All these phases are mechanically and dynamically stable by checking the elastic constants and phonon dispersion. All phases are direct band gap semiconductors except that the 蠅-Mg₃N₂ phase has a nontrivial indirect band gap. Mechanical properties calculations reveal that the 纬-Mg₃N₂ phase has superior ductility than other phases. The Vickers hardness of each phase has been evaluated to be about 15 GPa based on an empirical relation.