Energetical role of modeled intergranular glassy film in Si3N4–SiO2 ceramics Original Research Article

We have performed theoretical calculations to clarify the energetical role of an intergranular glassy film (IGF) by a static energy minimization technique using pair-potentials. A model structure of the IGF composed of silicon oxynitride (SON) is employed, which is consistent with the experimental electron energy-loss near-edge structure (ELNES). Two sets of calculations, i.e., for 0°- and 180°-twist boundaries, are done for Si3N4/SON/Si3N4 and Si3N4/Si3N4 interfaces. It is found that the presence of SON at the 180°-twist grain boundary is energetically favorable. The SON phase plays an important role in relieving the strain energy at the grain boundary. The dependence of the interface energy on composition of the SON phase is also discussed.