First-principles study of the effect of vacancies on the interface stability of 3C-SiC/Mg composites based on theoretical physical method

Abstract

In this paper, the first principles calculation method based on theoretical physics method was used to optimize the structure of 3C-SiC(111)/Mg(0001) interface model with vacancies. The interface adhesion work, vacancy formation energy and electronic structure were calculated and analyzed. The results show that the interface adhesion work of 3C-SiC/Mg-VMg −1、3C-SiC/Mg-VMg −2、3C-SiC/Mg-VMg −3 is greater than that of 3C-SiC/Mg which indicates that Mg vacancy have a certain promoting effect on the interface bonding of 3C-SiC/Mg, and the interface adhesion work of 3C-SiC/Mg- VMg − 1 is the largest. Because after the presence of Mg vacancy, the number of wavelet peaks increases and the pseudo-energy gap increases, so that the covalent bond increases and the interface adhesion work increases. Their vacancy defect formation energies are not much different, which are 1.1057eV, 1.0584eV, 1.2299eV, respectively. After the presence of C vacancy and Si vacancy, the interface adhesion work of 3C-SiC-VC − 1/Mg 、3C-SiC-VC − 3/Mg、3C-SiC-VSi − 2/Mg and 3C-SiC-VSi −4/Mg is smaller than that of 3C-SiC/Mg, which indicates that C vacancy and Si vacancy have no effect on the interface bonding. Among them, the interface adhesion work of 3C-SiC-VC −1/Mg is greater than that of 3C-SiC-VC −3/Mg, and the interface adhesion work of 3C-SiC-VSi −4/Mg is greater than that of 3C-SiC-VSi −2/Mg. After the presence of vacancy, the number of small wave peaks in the density of states map becomes less, the distribution of the density of states near the Fermi level becomes narrower, the metallicity is enhanced, and the bond strength decreases. In terms of the formation energy of vacancy defects, the formation energy of 3C-SiC-VC − 1/Mg is less than that of 3C-SiC-VC − 3/Mg, and the formation energy of 3C-SiC-VSi − 2/Mg is less than that of 3C-SiC-VSi − 4/Mg.