STRUCTURE AND BOND PROPERTIES OF COMPACTED AND HEAT-TREATED SILICON-NITRIDE PARTICLES

Particles of silicon nitride with dimensions < 15 nm are compacted int o macroscopic solids (nanostructured silicon nitride solids, NANO-SSNS ) and heat-treated under differing conditions. The structure and the b ond nature of these silicon nitride solids are investigated by X-ray r adial distribution functions, X-ray photoelectron spectra, X-ray diffr action patterns, and transmission electron microscopy observations. Th e particles do not grow after heat treatment at various temperatures b etween 25 and 1300-degrees-C, and the volume fraction of the interface in NANO-SSNS is still large and the interfaces remain characteristics of the initial solid. The structure of the interfaces is a new type o f short-range order structure differing from that inside the particles , i.e. the concentration of Si ions with coordination number < 4 is la rge. The bond structure of these materials is not the typical covalent bond. After heat treatments in the range 25 to 1300-degrees-C, specim ens retain the structure of the amorphous state.