Characterization of Silicon Carbide–Silicon Nitride Composite Ultrafine Particles Synthesized Using a CO ₂ Laser by Silicon‐29 Magic Angle Spinning NMR and ESR

Abstract

The structure of silicon carbide–silicon nitride (SiC–Si 3 N 4 ) composite particles synthesized using a CO 2 laser was studied by magic angle spinning nuclear magnetic resonance (MAS‐NMR) and electron spin resonance (ESR). The structure around Si atoms changed by introducing N. C atoms around Si were substituted by N atoms, and N‐rich configurations around Si atoms increased stepwise as the N content increased. The low N content composite particles consisted of mainly SiC phase containing dissolved N. N atoms were partly present in β‐SiC microcrystal and partly in the grain boundary layer in the particle. N atoms were tetrahedrally surrounded by four Si atoms in β‐SiC microcrystal and were trivalent state bonded to three Si atoms in the grain boundary layer. The high N content particles consisted of SiC, Si 3 N 4 , and amorphous phases, whose amount depended on N content.