Ab initio calculation of the evolution of [SiN 4‐ n O n ] tetrahedron during β ‐Si 3 N 4 (0001) surface oxidation

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