NMR characterisation of Si-based ultrafine laser formed powders

Abstract Ultrafine SiC, Si 3 N 4 and Si/C/N powders in the nanometric range ( 4 C 2 H 2 (or CH 3 SiH 3 ), SiH 4 NH 3 and SiH 4 CH 3 NH 2 NH 3 have been irradiated by a high power continuous wave CO 2 laser in a crossflow configuration cell. By varying the reaction conditions (flow rates and ratios of the reacting gases, laser power), amorphous to crystalline powders of variable size were formed. The powders were investigated by 29 Si and 13 C solid state NMR. A comparison of the different spectra obtained provides information on the local structure and composition of the materials.