No abstract

The easy‐going oxidation of silicon nitride (Si3N4) at high temperature greatly hampers its potential applications. Here, we explored the reaction mechanism between β‐Si3N4 and O2 via density functional theory (DFT) calculation, which discloses that O atoms are preferentially adsorbed on the top of Si atoms and N2 starts to be generated as the dominant gas product at 2/3 monolayer (ML) O coverage. The vacancies formed by N2 removal attract the O adatoms to transfer to the site of the N vacancy, which accelerates the adsorption of O and the formation of Si–O bonds toward the growth of SiO2 product. The surface oxidation of β‐Si3N4 (0001) has been clarified by the unambiguous evolution of [SiN4‐nOn] (n = 0‐4) tetrahedrons going through from [SiN4] tetrahedron to [SiO4] tetrahedron, providing a deep insight into intrinsic oxidation process of Si3N4 ceramic.