SYNTHESIS OF NANOMETER-SIZED SIC POWDERS THROUGH CHEMICAL-VAPOR-DEPOSITION III - EFFECT OF OVERALL CELL PRESSURE

In this paper, the effect of overall cell pressure on the particle siz e, size distribution, phase and chemical composition, shape and crysta llinity of SIC powders synthesized through chemical vapour deposition using a conventional heated furnace tube has been studied by means of transformation electron microscopy, S-ray diffraction (XRD), chemical analysis, X-ray photoelectron spectroscopy and IR absorption spectrosc opy. Experimental results reveal that both particle size and crystalli te size increase with increasing cell pressure due to the enhanced deg ree of supersaturation with respect to the chemical reaction. The comp osition of SiC powders can either be affected by cell pressure or rema in unchanged, depending on the C2H4/SiH4 mole ratio chosen. The shape of the powders is nearly spherical and the crystal form turns out to b e beta-SiC as evidenced by XRD analysis. (C) 1998 Elsevier Science S.A . All rights reserved.