IAM - Ceramic Materials and Technologies

Structure and chemistry of intergranular films in Ca-doped Si3N4

  • Author: Gu, H.; Pan, X.; Tanaka, I.; Cannon, R. M.; Hoffmann, M. J.; Mullejans, H.; Ruhle, M.
  • Source: INTERGRANULAR AND INTERPHASE BOUNDARIES IN MATERIALS, PT 2 207- (1996), 729–732
  • Structure and chemistry of intergranular films in Ca-doped Si3N4.

Abstract

Intergranular amorphous films at grain boundaries (GB) in Si3N4 ceramics doped with 0, 80, 220 and 450 ppm of calcia were investigated by high resolution transmission electron microscopy (HRTEM) and spatially-resolved electron energy-loss spectroscopy (EELS). The observed film thicknesses are consistent with previous observations [6]. Ca additives segregated at GB films, but not at the large triple pockets. EELS revealed the presence of N in the GB films. It is suggested that N is introduced into the GB films by Ca segregation. Electron energy-loss near-edge structure (ELNES) analysis indicates the presence of Si-(O,N)(4) tetrahedra in the GB films.