Hf-Ta-C-N四元化合物的结构、力学及电子性质的第一性原理研究

First-principles Study of Structures, Mechanical Properties and Electronic Properties of Quaternary Hf-Ta-C-N System

摘要: 基于进化算法和第一性原理计算，预测四元化合物Hf_xTa_8-xC₇N(x=1~7)的晶体结构。与二元HfC和TaC的晶体结构相似，这些四元Hf_xTa_8-xC₇N晶体结构属于岩盐结构。计算结果表明：随着有效价电子浓度(VEC)的增大，Hf_xTa_8-xC₇N的体模量逐渐增大；当VEC等于8.875时，剪切模量和杨氏模量达到最大值；维氏硬度在VEC等于8.25时达到最大值。因此，可以通过VEC的设计，得到具有综合力学性质优异的四元Hf_xTa_8-xC₇N化合物。计算Hf_xTa_8-xC₇N的电子性质，并分析力学性质与电子性质之间的关系。

Abstract: Based on evolutionary algorithm and first-principles calculation, crystal structures of quaternary compound Hf_xTa_8-xC₇N (x=1-7) were predicted. Similar to binary HfC and TaC, these compounds have a rock-salt structure. The calculation of mechanical properties shows that: With the increase of valence electron concentration (VEC), the bulk modulus of Hf_xTa_8-xC₇N increased gradually; At VEC=8.875, the shear modulus and elastic modulus are the largest; The Vickers hardness reaches the maximum at VEC=8.25. Therefore, the quaternary Hf_xTa_8-xC₇N compounds with excellent comprehensive mechanical properties can be obtained with the design of VEC. Finally, electronic properties of Hf_xTa_8-xC₇N compounds were calculated. Relations between mechanical properties and electronic properties were analyzed.