杂质S对Fe/Al2O3界面结合影响的第一性原理研究

摘要

采用基于密度泛函理论的第一性原理平面波赝势方法，研究了杂质S对Fe/Al2 O3界面结合的影响。计算结果表明： S在界面上Fe3原子处的界面偏析能最小，因此S易于向Fe3原子处偏析。 Fe/Al2 O3界面的结合主要受界面两侧Fe和O原子间相互作用控制。态密度、键重叠布居数和电子密度的计算结果均表明： S在界面处的偏析减弱了界面处Fe原子和O原子之间的相互作用，而且S的存在会引起Fe和O原子之间较强的静电排斥，这些导致了界面结合力的下降。研究结果可以使我们深入理解S在Fe-Cr-Al合金界面处的偏析造成氧化膜与合金基体结合减弱及氧化膜在S偏聚处剥离的机理。%The effect of S impurity on adhesion of Fe(110)/Al2O3(0001) interface is studied by the first-principles plane wave pseudopotential method within the density functional theory. It is shown that S impurity prefers to occupy the site of Fe3 at Fe(110)/Al2O3(0001) interface substitutionally due to the smallest interface segregation energy. The adhesion of Fe(110)/Al2O3(0001) interface is mainly governed by the interaction between Fe and O atoms on both sides of interface. The calculation results of the partial density of states, Mulliken overlap population and the electron density all suggest that Fe-O interaction is weakened by the segregated S impurity at Fe/Al2O3 interface, and the presence of S impurity gives rise to stronger electrostatic repulsion between Fe and O atoms across Fe/Al2O3 interface, which all leads to a reduced adhesion for Fe/Al2O3 interface. As a result, the results obtained by the first principles can give us a deeper understanding of the mechanism of a reduced interface adhesion and the oxidation film spallation by the segregation of S impurity at FeCrAl alloy interface.