Abstract
Ultrafine oxide particles of Si and Ge composite were synthesized in a gas-phasereactor devised to realise a reaction zone with a constant temperature profile. Premixed reactant gas was fed into the reactor to assure the composition of the reactant gases. Thus, the effects of temperature and the composition of Si and Ge in the reactant were experimentally studied by analyzing compositions of particles, types of Si·O·Ge network in particles, and particle size. The temperature range studied was 14501900K and the ratio of Si:Ge in the reactant gas was changed from 0:4 to 4:0, keeping the total mol fraction of Si and Ge 0.04. The following results were obtained. 1) At 1600-1750K, the content of Ge in particles became maximum. 2) The Ge composition in particles became larger with increase in Ge content of the reactant, but did not exceed the reactant composition. 3) At 1750K, the IR absorption of Si-O-Ge vibration became maximum. 4) Downstream of the particle formation zone, GeO2was depositted on the surface of particles due to the temperature decrease from over 1000 K to 500 K or so, and the particle size became almost twice the original size.
