Oxygen distribution in silicon nitride powders
The oxygen content of 10 si3N4 powders was determined by bulk chemical analysis and surface sensitive X-ray photoemission spectroscopy (XPS). In si3N4 powders prepared for reduction by si3N4 and sio2 and carbothermal reduction in nitrogen, only a small fraction of the 0.9 to 2.5 wt % total oxygen content in the surface layer is less than 1 nm thick, while the significant amount can be attributed to oxygen dissolution in most. However, powders made from the decomposition of silicon diimide are characterized by a higher oxygen concentration on the surface of the particles relative to the body, which may further reduce the chemical treatment. The surface layer composition corresponds to an intermediate state between silicon dioxide and silicon oxynitride.