OXIDE LAYER ON SILICON-CARBIDE POWDER - A FT-IR INVESTIGATION

The aim of this paper is to present a quick and sensitive method to determine the oxygen content in as received silicon carbide powders with different surface areas by FT-IR absorption spectroscopy. Pure silicon carbide has an intense infrared absorption band at 840cm(-1) with a shoulder at 950cm(-1), while silica exhibits an intense one at 1100cm(-1) and two others of lower intensity at 810 and 470cm(-1). The measure of the relative or absolute amount of the silica layer is possible using the molar extinction coefficient determined for SiC and SiO2. The oxygen content is deduced from the amount of silica, assuming that all the oxygen available is incorporated into silica. In order to throw away the edge of nu(Si-C) band in the nu(Si-O) one, the shoulder of the 950cm(-1) SiC absorption has been deconvoluted, which allows to get rid of any overlapping. So, the area of the silica band is deduced from the difference between the experimental and the deconvoluted spectra