Synthesis of ultrafine Si3N4 powder in RF-RF plasma

Conference · Tue Oct 01 00:00:00 EDT 1991 · Ceramic Engineering and Science Proceedings; (United States)

OSTI ID:5949896

Sato, Michitaka; Nishio, Hiroaki

A newly designed plasma-CVD apparatus mounted with the RF-RF type plasma torch was introduced to synthesize ultrafine powders of silicon nitride (Si3N4). The RF-RF plasma system (the combination of a main (lower) and controlling (upper) RF plasma) improved the stability of simple RF plasma and solved the impurity problem of dc-RF hybrid plasma. The reaction of SiCl4 and NH3, which were radially injected into the tail flames of the upper and lower plasmas, respectively, yielded near-stoichiometric amorphous powders of Si3N4. The nitrogen content in the products largely depended on the flow rate of the quenching gas, a mixture of NH3 (reactant) and H2. The oxygen content and metal impurities are 2-3 wt pct and less than 200 ppm, respectively. The powder particles had an average diameter of about 15 nm with a narrow size distribution, and showed extreme air sensitivity. Conspicuous crystallazation and particle growth occurred when heated at temperatures above 1400 C. These results suggested that the RF-RF system was a potential reactor for the synthesis of ultrafine powders with excellent sinterability at relatively low temperatures. 9 refs.

• OSTI ID: 5949896
• Report Number(s): CONF-910162-; CODEN: CESPD
• Journal Information: Ceramic Engineering and Science Proceedings; (United States), Vol. 12; Conference: 15. annual conference on composites and advanced ceramics, Cocoa Beach, FL (United States), 13-16 Jan 1991; ISSN 0196-6219
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
SILICON NITRIDES
SYNTHESIS
AMORPHOUS STATE
CERAMICS
CHEMICAL VAPOR DEPOSITION
CRYSTALLIZATION
FLAMES
IMPURITIES
OXYGEN
PLASMA JETS
POWDERS
STOICHIOMETRY
CHEMICAL COATING
DEPOSITION
ELEMENTS
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
PHASE TRANSFORMATIONS
PNICTIDES
SILICON COMPOUNDS
SURFACE COATING
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication