Laser Synthesis and Characterization of Si/C/N Ceramic Powders

✍ Scribed by Doh?evi?-Mitrovi?, Z.D. ;Popovi?, Z.V.

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 176 KB
• Volume: 181
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/1521-396x(200010)181:2<347::aid-pssa347>3.0.co;2-l

✦ Synopsis

We presented both laser synthesis and characterization of ultrafine nanometric (12 to 20 nm diameter) Si/C/N powders starting from NH 3 , SiH 4 and C 2 H 2 gas mixture, using a continuous-wave CO 2 laser. The main parameters affecting this process are: the reactant flow ratio R F NH3 =F SiH4 , the C 2 H 2 flow rate, the pressure cell and the laser power. These parameters strongly influence and change the temperature of the reaction which affects the size, stoichiometry and crystallinity of the particles. Infared Fourier transform reflection spectroscopy and X-ray diffraction analysis have been employed to investigate the final composition of the powders. Our results point out that for low values of R (R 0:5 to 1) Si/C/N powders are a mixture of amorphous phase, ascribed to ternary compound and crystalline b-SiC, while for higher R values (R > 1) C atoms enter substitutionally into the matrix of amorphous Si 3 N 4 giving rise to a ternary compound where most Si atoms have the local structure C x ±Si±N 4 À x .