Temperature and pressure dependence on mechanical properties and defect formation structure in 3C-SiC: A molecular dynamics study
Hadiseh Rabiee
Abstract
• The elastic response is almost dependent on temperature and pressure. • Point defects have more influence than temperature and pressure on elastic properties. • Pressure has more effect than temperature on stability criteria. • The defective formation has a stable trend over 30 GPa and 500 C in the Stability criteria, Elastic constants, Cauchy pressure, Pugh's ratio and Hardness. • Temperature and pressure reverse elastic properties. • Perfect and defect formations are reversed on the mechanical properties. Silicon carbide (SiC) is well known for its hardness and crystalline structure in ceramics, making it a suitable material for cladding in fuel reactors. In this study, first-principles calculations were employed to examine the dependence of the mechanical properties of silicon carbide on pressure and temperature by analyzing their correlation with elastic constants. We investigated the mechanical stability, elastic properties, brittleness, ductility, and hardness of both perfect and defective unit cells under various temperature and pressure conditions. Mechanical properties were evaluated for both types of unit cells across different pressures and temperatures. Our results indicate that the perfect 3C-SiC structure is more stable than the defective one at high pressures and temperatures. The maximum pressure and temperature considered in this study were 50 GPa and 1100 C, respectively. Interestingly, the structure with point defects exhibits greater resistance than the perfect structure under applied pressure and temperature conditions. The elastic constants of the perfect unit cell increase more significantly than those of the defective cell under pressure, suggesting that elastic constants remain more stable in the defective structure. Our findings indicate that silicon carbide can withstand pressure and temperature variations up to 20 GPa and 500 C. The perfect unit cell exhibits brittle behavior, whereas the defective structure shows a ductile trend as pressure increases. With increasing temperature, the perfect structure transitions to a more ductile behavior, while defective cells tend to fail. Moreover, higher temperatures lead to an increase in hardness in the perfect cell but a decrease in hardness in defective cells. Additionally, as pressure increases, hardness decreases in the perfect structure while increasing in the structure with point defects.