First-principles study of the structural, mechanical, magnetic, and electronic properties of Cr₄AlN₃ under pressure

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• 作者：Chenliang Li ; Zhenqing Wang ; Decai Ma ; Chaoying Wang ; Baolai Wang
• 关键词：A. Ternary alloy systems ; E. Ab-initio calculations ; E. Phase stability ; E. Electronic structure
• 刊名：Intermetallics
• 出版年：2013
• 出版时间：December, 2013
• 年：2013
• 卷：43
• 期：Complete
• 页码：71-78
• 全文大小：1227 K

文摘

This work investigates the pressure dependence of the structural, mechanical, magnetic, and electronic properties of Cr₄AlN₃ using a first-principles method. Analysis confirms that the ¦Á-Cr₄AlN₃ phase is more stable than the ¦Â-Cr₄AlN₃ phase and that Cr₄AlN₃ is more compressible along the a direction than along the c direction. The calculated elastic anisotropic factors indicate that Cr₄AlN₃ has a higher degree of anisotropy than other M₄AX₃ compounds, that Cr₄AlN₃ is mechanically stable in the pressure range of 0-60?GPa, and that its elastic constants and bulk modulus monotonously increase as pressure increases. Additionally, ¦Â-Cr₄AlN₃ has better mechanical properties than ¦Á-Cr₄AlN₃, while the G/B value of ¦Á-Cr₄AlN₃ is currently the lowest among all reported M_n+1AX_n compounds. These results also show that the ground state of Cr₄AlN₃ is ferromagnetic, and the magnetic moments of Cr₄AlN₃ decrease as pressure increases. The electronic structure calculations indicate that the appearance of the ferromagnetic state in Cr₄AlN₃ derives mainly from the 3d electrons of the Cr atoms, and that the Cr-N bonding is stronger than the Cr-Al bonding. Finally, analysis shows that Cr₄AlN₃ does not undergo a structural phase transformation at high pressure (10-60?GPa).