First-principles investigation of novel polymorphs of Mg2C

文献情報

出版日 2015-04-10

DOI 10.1039/C5CP00001G

インパクトファクター 3.676

著者

Changzeng Fan, Jian Li

原文を見る

要旨

On the basis of the evolutionary methodology for crystal structure prediction, the potential crystal structures of magnesium carbide with a chemical composition of Mg2C are explored. Except the known cubic phase (Fmm), two novel tetragonal structures (P42/mnm and I41/Amd) and two novel hexagonal structures (P63/mmc and PM2) of Mg2C are found. All these four new phases are mechanically and dynamically stable by the calculated elastic constants and phonon dispersions. Furthermore, the effects of pressure and temperature on the phase transitions among different Mg2C polymorphs are investigated, implying that some new phases especially the P42/mnm phase may be synthesized in future. The ratio values of B/G are also calculated in order to analyze the brittle and ductile nature of these Mg2C phases. In addition, electronic structure calculations suggest that the I41/Amd phase is semimetallic and the other three new phases are all metallic, which is different from the previously proposed magnesium carbides. Meanwhile, the calculated electronic density maps reveal that strong ionic bonding exists between the Mg and C atoms.

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

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