First-Principles Study on Properties of the Native Defects in Al2O3(110) Surface

Resumo

Using the CASTEP module in Materials Studio software, the native defect model structures including O vacancy and Al vacancy in Al₂O₃(110) surface were designed and constructed. Through first-principles based on density functional theory (DFT) and pseudo potential method, the Al₂O₃(110) model structures were optimized. Formation energy, energy state structure, electric density and electron population of defect structures and primitive cell were calculation. Effect of O vacancy and Al vacancy on Al₂O₃ properties could be analyzed and probed. The results showed that formation energy of O vacancy is only 0.06 eV, which is significantly less than that of Al vacancy (2.99 eV). This indicates that the formation of O vacancy is more easily to produce. O vacancy defects reduce electronic energy in Al₂O₃(110), and make its conductivity become poorer. The impact of Al vacancy defects on conductivity are opposite. The influence of aluminum vacancy defects on electron density in Al₂O₃(110) is more than that of oxygen vacancy; oxygen vacancy increases the electronegativity around O atoms, and weakens electropositivity around Al atoms the electricity, which makes the top of energy band structure move down. The calculation results provide a theoretical guidance for the formation of functional anodic oxidation films of Al.