Determination of phase composition of silicon nitride powders by silicon-29 magic angle spinning nuclear magnetic resonance spectroscopy

The use of solid-state exp 29 Si NMR spectroscopy to analyze Si sub 3 N sub 4 powders is demonstrated for a series of commercial and research samples. In particular, two different commercial powders contain 20 and 30% amorphous Si sub 3 N sub 4 content, as identified by the application of methods described. These same materials had been analyzed by X-ray diffraction as only crystalline Si sub 3 N sub 4 . NMR spectroscopy is capable of distinguishing among different amorphous Si species normally found in preparations of Si sub 3 N sub 4 powders. These include amorphous Si sub 3 N sub 4 , silicon oxynitrides, silicates, and elemental Si. The measurement of concentration of these species is made for correlation with properties of powder sinterability. 18 ref.--AA