Oxygen impurity effects on the mechanical properties of SiC studied by first principles calculations

First principle calculations are performed to study the oxygen doping effects on the mechanical properties of SiC. Both interstitial and substitutional oxygen atoms decrease the shear and tensile modulus and strength of SiC. The substitutional oxygen atoms decrease the shear and tensile modulus and strength more than the interstitial oxygen atoms do. Local distortions around the oxygen doping atoms are found in both of tensile and shear stress strain curve calculations in the elastic region. The shear strength of SiC decreases linearly with the increase of the oxygen concentration. The tensile strength of SiC also decreases with the oxygen concentration and it drops dramatically at low concentration region.