Synthesis of Silicon Carbide–Silicon Nitride Composite Ultrafine Particles Using a Carbon Dioxide Laser

The synthesis and the structure of silicon carbide-silicon nitride (SiC─Si₃N₄) composite ultrafine particles have been studied. SiC─Si₃N₄ composite ultrafine particles were prepared by irradiating a SiH₄, C₂H₄, and NH₃ gas mixture with a CO₂ laser at atmospheric pressure. The composition of composite powders changed with the reactant gas flow rate. The carbon and nitrogen content of the powder could be controlled in a wide range from 0 to 30 wt%. The composite powder, which contained 25.3 wt%. carbon and 5.8 wt% nitrogen, had a (β-SiC structure. As the nitrogen con- tent increased, SiC decreased and amorphous phase, Si₃N₄, Si appeared. The results of XPS and lattice constant measurements suggested that Si, C, and N atoms were intimately mixed in the composite particles.