Laser Chemical Vapor Precipitation of Ceramic Powders

摘要

The formation of optimal silicon nitride powders is studied by using as synthesistechnique Laser Chemical Vapor Precipitation (LCVP). The combination of gas phase reaction and laser heating technique results in an optimal control of the particle sizes and, because it is a cold wall, in a strong reduction of impurities. Reactor development and other experimental aspects are described and laser synthesis of the following are detailed: low agglomerated Si3N4 powders from SiH2Cl2; Si3N4 fibers from SiH2Cl2 and NH3; and Si3N4 powders by NH3 excitation. The use of sensitizers in the formation of Si and Si3N4 powders from chlorinated silanes in CO2 laser reactions is addressed. SiF4 as silicon precursor for the synthesis of Si3N4 by LCVP is reported.