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research papers
Amorphous polyborosil azane bulk ceramics are prepared by heat treatment above 1273 K from organometallic bulk precursors which are formed by sintering precursor powders using cold isostatic pressing. A structural change during the conversion process of the polyborosilazane bulk precursors causes a change of small-angle X-ray scattering (SAXS) profiles in the high q region. The analysis of the SAXS intensities indicates that the size of the precipitates increases monotically with increasing heat-treated temperature and that they develop to small particles with sharp interfaces distributed in the amorphous phase after heat treatments above 1173 K. All the scattering profiles of the polyborosil azane bulk specimens throughout the conversion process can be fitted using the PercusYevick model of particle scattering including the concept of adepleted zone. The SAXS measurements show that the structural inhomogeneities originating from organometallic polymers arechanged by the heat-treatment above about 973 K to structures where the nano-sized precipitates embedded in the amorphous matrix occupy smaller volume fractions compared with those heat treated below 873 K.