ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 47, (3) 88 - 93 (2003)

Halamka Martin 1, Kavecký Štefan 2, Dočekal Bohumil 3, Madejová Jana 4, Šajgalík Pavol 4
1 Technical University Brno, Faculty of Chemistry Purkyňova 118, 612 00 Brno, Czech Republic
2 Institute of Materials and Machine Mechanics, Slovak Academy of Sciences Račianska 75, 831 02 Bratislava, Slovak Republic
3 Institute of Analytical Chemistry, Academy of Sciences of Czech Republic Veveří 97, 611 42 Brno, Czech Republic
4 Institute of Inorganic Chemistry, Slovak Academy of Sciences Dúbravská cesta 9, 842 36 Bratislava, Slovak Republic

Keywords: Nanopowders, SiC, Si₃N₄, CVD, Metal impurities

Fine, sub-micrometer, amorphous powders of SiC and Si₃N₄ have been prepared from SiH₄ - NH₃ and C₂H₂ - SiH₄ gaseous systems respectively, in tubular flow reactor. The Si3N4 powder prepared at 1373 K and NH₃/SiH₄ molar ratio of 11.5 is near stoichiometric in composition, isometric in morphology and the particle size is in range of 50 - 150 nm. The particle size of SiC powder prepared at 1373 K and SiH₄/C₂H₂ molar ratio of 2:1 was from the interval 10 to 100 nm. Recrystallization of these powders at 1853 K did not change substantially the particle size distribution and confirmed the Si₃N₄ and SiC as major compounds respectively. The content of metal impurities as Al, Cr, Cu and Fe in the presented powders is one order of magnitude lower compared to the commercially available powders prepared by other methods.

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