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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。
The electronic structure, elastic constants and Mullikan population of Nb and Al co-doped MoSi2 crystals have been studied by first-principles calculations. The results show that the co-doping of Nb and Al can greatly improve the toughness and electrical conductivity of MoSi2. When the co-doping amount of Nb and Al reaches x = 0.25, the elastic modulus of MoSi2 decreases from 408.86GPa to 261.30GPa. The analysis of MoSi2 electron density and Mullikan population shows that the density of MoSi2 electrons shifts to blue after the addition of Nb and Al, and the charge density increases at the Fermi level and the conductivity of the system increases. After doping, the number of Mo-Al and Nb-Si bonds decreased, the bond length increased, the covalency between atoms decreased, and the covalency between Al-Si bonds increased. The distribution of the bond length and bond energy in each direction tends to be symmetrical in the crystal, and the toughness of the MoSi2 crystal is enhanced.