Nb、Al共掺杂MoSi2弹性性质的第一性原理计算

通过第一性原理计算研究了Nb、Al共掺杂MoSi2晶体的电子结构、弹性常数和Mullikan布居数。结果表明,Nb、Al共掺杂可大幅提高MoSi2的韧性和导电性,当Nb和Al共掺杂量达到x=0.25时,MoSi2的弹性模量从408.86GPa降低到261.30GPa。MoSi2的电子态密度和Mullikan布居数分析表明,Nb和Al掺入后MoSi2电子态密度发生蓝移,费米能级处的电荷密度增加,体系的导电性能提高。掺杂后Mo-Al、Nb-Si键布居数减小,键长增大,原子间的共价性减弱,而Al-Si键间的共价性增强。晶体中各方向键长和键能的分布趋于对称化,MoSi2晶体韧性增强。

First-Principles Calculation of Elastic Properties of Nb and Al Codoping MoSi2

The electronic structures, elastic constants and Mullikan population of Nb and Al codoped MoSi2 were calculated by the density functional theory. The results show that the co-doping of Nb, Al can improve greatly the toughness and conductivity of MoSi2. When the doping volume of Nb and Al reaches to x= 0.25, the elastic modulus of MoSi2 decreases from 408.86 GPa to 261.30 GPa. By analyzing the density of states and Mullikan population, after doping the total density of states has a blue-shift, the charge density on Fermi level increases, the conductivity of the system improves and Mo-Al and Nb-Si bond populations decreases with their bond lengths increase. In addition, the covalent between atoms weakens, while the covalent bonds between Al and Si enhances. As the distribution of bond length and bond energy along each crystal orientation tends to be symmetrical, the fracture toughness of doped MoSi2 would improve.