The mechanical and thermodynamic properties of β-Si1-xC

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 beta-Si1-xC. Our results show that the volume of the beta-Si1-xC crystal decreases when the x value increases, while the density of beta-Si1-xC increases when the x value increases. When the x value is smaller than 0.8148, the formation energy of beta-Si1-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 beta-Si1-xC declines with the increase of x value, which indicates that the stability of beta-Si1-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 beta-Si1-xC decreases when the x value increases. There is a nearly linear relationship between the thermodynamic properties of beta-Si1-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 beta-SiC.