Preparation of SiC hollow particles by gas-phase reaction in the SiH4-CH4-H2 system

The formation of SiC hollow particles by gas-phase reaction in the silane-methane-hydrogen system was studied at temperatures from 1200 to 1400° C. Synthesized powders were analysed by means of the thermogravimetry, X-ray diffraction, transmission electron microscopy, infrared irradiation, etc. The powders synthesized at 1200 to 1300° C consisted ofβ-SiC and silicon phases, but they became almost hollowβ-SiC particles at 1400° C. The composition, particle size, and shell thickness of the synthesized particles were dependent on the reaction conditions. From lattice parameter measurements, a certain amount of excess silicon was verified to be incorporated into theβ-SiC lattice. On the other hand, excess carbon existed, for the most part, as an amorphous phase not forming solid solutions withβ-SiC. Transmission electron microscopy observations and infrared absorption measurements have shown that excess carbon is contained within the shells of hollow particles, while unreacted excess silicon exists as a crystalline phase mostly in the cores of the particles.