Calculated structural, electronic and elastic properties of M2GeC (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W)
Calculated structural, electronic and elastic properties of M2GeC (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W)
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DOI：
10.1007/s00339-009-5106-5
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发表时间：
2009-09-01
影响因子：
2.7
通讯作者：
Bouhemadou, A.
中科院分区：
文献类型：
--
作者：
Bouhemadou, A.
用从头计算方法研究了M_2GeC（M=Ti，V，Cr，Zr，Nb，Mo，Hf，Ta，W）的结构、电子和弹性性质。晶胞的几何优化结果与实验数据吻合较好。能带结构表明，所有研究的材料都是电导体。通过对位密度和动量投影密度的分析表明，成键主要是由于Md-Cp和Md-Gep杂化。弹性常数的计算采用静态有限应变技术。剪切模量C（44）与硬度直接相关，当价电子浓度在8.41-8.50范围内时达到最大值。我们推导出的体积和剪切模量，杨氏模量和泊松比的理想多晶M2 GeC聚集体。我们从平均声速估算了M2 GeC的德拜温度。这是首次对Ti_2GeC、V_2GeC、Cr_2GeC、Zr_2GeC、Nb_2GeC、Mo_2GeC、Hf_2GeC、Ta_2GeC和W_2GeC等化合物弹性常数的定量理论预测，目前尚待实验验证。
Using ab initio calculations, we have studied the structural, electronic and elastic properties of M2GeC, with M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W. Geometrical optimizations of the unit cell are in agreement with the available experimental data. The band structures show that all studied materials are electrical conductors. The analysis of the site and momentum projected densities shows that bonding is due to M d-C p and M d-Ge p hybridizations. The elastic constants are calculated using the static finite strain technique. The shear modulus C (44), which is directly related to the hardness, reaches its maximum when the valence electron concentration is in the range 8.41-8.50. We derived the bulk and shear moduli, Young's moduli and Poisson's ratio for ideal polycrystalline M2GeC aggregates. We estimated the Debye temperature of M2GeC from the average sound velocity. This is the first quantitative theoretical prediction of the elastic constants of Ti2GeC, V2GeC, Cr2GeC, Zr2GeC, Nb2GeC, Mo2GeC, Hf2GeC, Ta2GeC and W2GeC compounds, and it still awaits experimental confirmation.