First-principles study of the structural and elastic properties of Cr2AlX (X=N, C) compounds
First-principles study of the structural and elastic properties of Cr2AlX (X=N, C) compounds
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Cr2AlX(X=N,C)化合物结构与弹性性能的第一性原理研究
DOI：
10.1016/j.jssc.2012.03.014
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发表时间：
2012-07-01
影响因子：
3.3
通讯作者：
Gong, Zizheng
中科院分区：
文献类型：
--
作者：
Cui, Shouxin;Wei, Dongqing;Gong, Zizheng
采用平面波赝势方法，在密度泛函理论水平上研究了Cr（2）AIX（X=N，C）的结构、电子和弹性性质.能带结构和态密度揭示了Cr（2）AIX的金属特征。总的和投影的态密度表明，通过与Al和X-原子p态的Cr 3d态的杂化实现成键。Cr 3d-X2 p键比Cr 3d-Al 3 p键的能量更低并且更硬。电荷密度分布表明，合金中存在较软的Cr-Al键和较强的Cr-X共价键，这可能是合金硬度的主要原因。在0-100 GPa压力范围内，得到了两种化合物的弹性常数，满足六方晶体的稳定性条件，表明这两种化合物在所研究的压力范围内是稳定的。通过分析体积模量与剪切模量之比和柯西压力，预测Cr（2）AIC为脆性，Cr（2）AlN为韧性。德拜温度由平均声速求得。皇冠版权所有（C）2012由Elsevier Inc.发布。All rights reserved.
The structural, electronic and elastic properties of Cr(2)AIX, with X=N, C, have been investigated at the density functional theory level by applying a plane-wave pseudopotential approach. The band structure and density of states reveal the metallic features of Cr(2)AIX. The total and projected density of states indicate that the bonding is achieved through a hybridization of Cr 3d states with Al and X-atom p states. The Cr 3d-X2p bonds are lower in energy and are stiffer than Cr 3d-Al 3p bonds. The charge density distributions indicate that there exist soft Cr-Al and relatively strong Cr-X covalent bonds, which might be responsible for their hardness. The elastic constants were obtained in the pressure range 0-100 GPa, and satisfy the stability conditions for hexagonal crystal, which indicates that these two compounds are stable in the pressure regime studied. By analyzing bulk modulus to shear modulus ratio and Cauchy pressure, Cr(2)AIC is predicted to be brittleness and Cr(2)AIN is ductile. The Debye temperature was obtained from the average sound velocity. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.