The mechanical and thermodynamic properties of β-Si1−xC

Abstract

By using the first-principles calculation method based on density functional theory (DFT), we investigated the stability, mechanical properties and thermodynamic performance of the carbon-rich β-Si_1−xC. Our results show that the volume of the β-Si_1−xC crystal decreases when the x value increases, while the density of β-Si_1−xC increases when the x value increases. When the x value is smaller than 0.8148, the formation energy of β-Si_1−xC increases when the x value increases, whereas when the x value is larger than 0.8148, the formation energy decreases when the x value increases.The binding energy value of β-Si_1−xC declines with the increase of x value, which indicates that the stability of β-Si_1−xC decreased as the x value increases. The bulk modulus, shear modulus and Young modulus increase upon increasing the x value, but the Poisson’s ratio of β-Si_1−xC decreases when the x value increases. There is a nearly linear relationship between the thermodynamic properties of β-Si_1−xC and the x value, and the change in the thermodynamic properties is mainly due to the change in the lattice vibration. Our results provide theoretical support for the development of β-SiC.