第一性原理研究合金元素对3C-SiC/Mg界面的影响

First-Principles Study on Effect of Alloying Elements on 3C-SiC/Mg Interface

摘要:

采用基于密度泛函理论的第一性原理方法，研究掺杂单个Al、Zn、Cu、Ni、Li、Zr原子对3C-SiC/Mg体系界面结合的影响，选取代表性的Zn原子和Zr原子进行Mulliken电荷、重叠布居数和态密度计算分析。结果表明，3C-SiC/Mg界面模型最稳定的堆垛结构是将5层的Mg（0001）堆垛在10层的 3C-SiC（111）面上，C封端的中心型模型在6种3C-SiC/Mg模型结构中分离功最大，界面间距最小，界面的润湿性最好；掺杂Zn原子后，3C-SiC/Mg-Zn体系的分离功减小，掺杂的Zn原子与Mg原子成反键，态密度中赝能隙变小使得3C-SiC/Mg-Zn体系的共价键性减弱，不利于3C-SiC/Mg-Zn界面结合； 掺杂Al、Cu、Ni、Li、Zr原子后，体系的分离功增大，Zr原子对界面润湿性的改善效果最好。掺杂Zr原子后，界面层Mg原子与Si原子的反键消失，与C原子在界面处形成Zr-C强共价键，态密度离域性增强，成键能力增强，导致3C-SiC/Mg-Zr体系的分离功增大最多。

Abstract:

Effects of doping single Al, Zn, Cu, Ni, Li, and Zr atoms on interfacial bonding in the 3C-SiC/Mg system were studied using the first-principles method based on density functional theory. The Mulliken charge, overlapping population and density of states of representative Zn and Zr atoms were calculated and analyzed. Results show that the most stable stacking structure of the 3C-SiC/Mg interface model is that 5-layer Mg(0001) is stacked on the 10-layer 3C-SiC(111) surface. Among the six 3C-SiC/Mg model structures, the C-terminated center site model has the largest separation energy, the smallest interfacial spacing and the best interfacial wettability. After doping with Zn atom, Zn and Mg atoms are in the anti-bonding state, resulting in the decrease of the separation work of the 3C-SiC/Mg-Zn system. The decrease of the pseudo-energy gap in the density of states weakens the covalent bond in the 3C-SiC/Mg-Zn system, and this is not conducive to interfacial bonding in the 3C-SiC/Mg-Zn system. After doping with Al, Cu, Ni, Li, and Zr atoms, the separation work of the system increases, and Zr has the best effect on improving the interfacial wettability. After doping with Zr, the anti-bonding state of Mg and Si atoms disappears, and a strong Zr-C covalent bond is formed at the interface between the Zr atom and C atom. The delocalization of the density of states increases, and the bonding ability is enhanced, resulting in a maximum increase in the separation work of the 3C-SiC/Mg-Zr system.