Solid‐State 29Si NMR Analysis of Amorphous Silicon Nitride Powder

Abstract

Solid‐state 29 Si NMR techniques were used to characterize laser‐synthesized silicon nitride powder prepared from the reaction of silane with ammonia. When the powder is exposed to water vapor, a hydrated layer rapidly forms at the surface. A comparison of 29 Si cross polarization (CP) and Bloch decay (BD)‐MAS‐NMR spectra revealed differences between surface and bulk compositions. CP‐NMR identified Si‐NH x (x = 1, 2) species with a chemical shift of −45 ppm in the as‐synthesized ( unexposed ) powder. In BD‐NMR spectra, the nitride resonance is observed at −48 ppm. For the hydrated powder, CP‐NMR identified additional =Si‐OH ( Q 3 ), =Si‐(OH) 2 ( Q 2 ), and SiO 2 ( Q 4 ) species present at the surface. The CP‐NMR spectra were corrected for T lpH relaxation effects and deconvoluted into individual components in order to extract quantitative measurements of the various species present.