Nanophase powders of Si, C, and SiC with narrow size distributions are synthesized by dissociating reactants in a dc arc plasma and quenching the hot gases in a subsonic nozzle expansion. The plasma is characterized by calorimetric energy balances and the powders by on-line aerosol measurement techniques and conventional materials analysis. The measured nozzle quench rate is about 5 × 106 K/s. The generated particles have number mean diameters of about 10 nm or less, with Si forming relatively dense, coalesced particles, while SiC forms highly aggregated particles. Our data suggest that SiC particle formation is initiated by the nucleation of small silicon particles.
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation under Grant ECS-9118100, and by the Minnesota Supercomputer Institute. We thank Mr. Mark Presia from the University of Ilmenau, Germany, for discussions on the formation of amorphous hydrogenated silicon.