Plasma functionalization of silicon carbide crystalline nanoparticles in a novel low pressure powder reactor

In order to functionalize silicon carbide nanopowders with carboxylic groups, an r.f. (13.56 MHz) low pressure plasma reactor has been developed so that particles can be stirred during the processing to try to coat them on their whole surface. Coatings in an O₂/hexamethyldisilazane (HMDSN) mixture have first been optimized on flat substrates; X-ray Photoelectron Spectroscopy (XPS) analysis showed that the O₂/HMDSN gas mixture resulted in a coating evolving from a polymer-like structure to a more inorganic SiO_x-like structure as the oxygen ratio increased. For a large O₂/HMDSN value, carboxylic groups were detected on the sample surface. Silicon carbide nanoparticles have then been plasma processed in such a reactive atmosphere. XPS, Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) and Transmission Electron Microscopy (TEM) analyses evidenced the surface modification of the processed powder and confirmed the grafting of carboxylic groups.