Combined infra-red and X-ray studies of ?-silicon nitride and ??-sialons

• DOI: 10.1007/bf00548740
• Publication Date: 2004-11-19T08:28:29Z
• Authors: S. Wild; H. Elliott; D. P. Thompson
• Keywords: 0205 materials engineering; 02 engineering and technology

Previous investigations of the replacement of silicon by aluminium and nitrogen by oxygen in β-silicon nitride have been based primarily on X-ray powder diffraction studies. In the present work this technique is coupled with parallel infra-red studies. X-ray analyses of sialons over a wide composition range confirm previous observations that increasing substitution of aluminium for silicon and nitrogen for oxygen in β-silicon nitride is accompanied by an increase in cell size, with no evidence of any other structural modification. Parallel infra-red analyses show shifts in certain of the infra-red absorption bands to lower wavenumbers as the degree of substitution increases. Changes in the infrared spectra at the composition Si2Al4N4O4 indicate structural modifications which are not apparent from the X-ray investigations. It is suggested that these changes are a result of the ordering of the different atom types at this composition.