Crystallization behavior of polymer-derived Si–B–C–N ceramics in a high-pressure nitrogen environment

This communication presents the effects of nitrogen pressure on the crystallization behavior of Si_3.0B_1.1C_5.3N_3.0 ceramics annealed at 1800 °C for 3 h. Transmission electron microscopy observation reveals that increasing nitrogen pressure results in the retardation of the crystallization process. Besides SiC and Si₃N₄ nanocrystals, individual large crystallites were also detected. These crystals were composed only of Si and N, and they possessed hexagonal structure with lattice parameters a = 0.737 nm and c = 0.536 nm. Crystallites of this novel phase were more frequently found with increased nitrogen pressure.