Chapter 33. Synthesis of Ultrafine Si3N4 Powder in RF-RF Plasma
- John B. Wachtman Jr
Published Online: 26 MAR 2008
Copyright © 1991 The American Ceramic Society, Inc.
Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 9/10
How to Cite
Sato, M. and Nishio, H. (1991) Synthesis of Ultrafine Si3N4 Powder in RF-RF Plasma, in Proceedings of the 15th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 12, Issue 9/10 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470313848.ch33
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 1991
Print ISBN: 9780470375105
Online ISBN: 9780470313848
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 (N: 38 wt%) 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% 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.