SURFACE CHEMICAL-SPECIES INVESTIGATION BY FT-IR SPECTROMETRY AND SURFACE MODIFICATION OF A NANOSIZED SICN POWDER SYNTHESIZED VIA CHEMICAL-VAPOR CONDENSATION

The surface of a nanosized silicon carbonitride powder synthesized by chemical vapor condensation from hexamethyldisilazane was analyzed by FT-IR spectrometry. Several chemical species were identified, and thei r behavior toward probe molecules was studied. Deuterium and methanol additions brought evidence of open pores. A slight oxidation led to po re coalescence and strong modifications in the chemical composition of the first atomic layer even though a complete silica coverage was not reached. Moreover, the SiCN surface further nitrided by ammonia addit ion at high temperature appeared to have, under those conditions, a be havior different from the silicon carbide surface.